Things that should be found in an emergency preparedness kit
By MANILA BULLETIN ONLINE
September 4, 2010, 4:49am
You will never know when there is going to be an emergency like a strong typhoon or an earthquake, so it is very important to be prepared all the time. Being prepared includes having an emergency preparedness kit. Shine from Yahoo enumerates 10 things that must be found in your kit.
1. Water – Store water that will last three days for the whole family. This is not only for drinking but for other purposes as well.
2. Food – Ready easy-to-open canned goods good for three days.
3. First aid kit – You can buy this from the pharmacy. This includes antiseptic, latex gloves, cleansing agents, scissors, bandages, thermometer, and lubricants. It is also advised that you include pain relievers like ibuprofen.
4. It is also good to keep tools such as a hammer, screwdriver, and can opener.
5. Extra clothing, just in case you need to stay somewhere else. The clothes you will pack will depend on the season.
6. Beddings like blankets for warmth and shelter.
7. Emergency light, radio, and batteries in case of a power outage.
8. A whistle is an effective way to signal or call attention in case you are trapped in a place.
9. Copies of birth certificate, a phone book, and other important documents. These must be kept in waterproof bags.
10. Other things that are of great use to the family such as feeding bottles and eyeglasses.
Place your kit somewhere you can easily get it in your house. Check and update your kit at least once a year.
http://www.mb.com.ph/articles/275485/things-should-be-found-emergency-preparedness-kit
Sunday, March 20, 2011
Earthquake
Earthquake
An earthquake is a geological event inside the earth that generates strong vibrations. When the vibrations reach the surface, the earth shakes, often causing damage to natural and man-made objects, and sometimes killing and injuring people and destroying their property. Earthquakes can occur for a variety of reasons; however, the most common source of earthquakes is movement along a fault.
Some earthquakes occur when tectonic plates, large sections of Earth's crust and upper mantle, move past each other. Earthquakes along the San Andreas and Hayward faults in California occur because of this. Earthquakes also occur if one plate overruns another, as on the western coast of South America , the northwest coast of North America , and in Japan. If plates collide but neither is overrun, as they do crossing Europe and Asia from Spain to Vietnam, earthquakes result as the rocks at the abutting plates compress into high mountain ranges. In all three of these settings, earthquakes result from movement along faults.
A fault block may also move due to gravity , sinking between other fault blocks that surround and support it. Sinking fault blocks and the mountains that surround them form a distinctive topography of basins and mountain ranges. This type of fault block configuration is typified by the North American Basin and Range topographic province. In such places, elevation losses by the valleys as they sink between the mountains are accompanied by tremors or earthquakes. Another kind of mountain range rises because of an active thrust fault. Tectonic compression (tectonic, meaning having to do with the forces that deform the rocks of planets) shoves the range up the active thrust fault, which acts like a natural ramp.
Molten rock called magma moves beneath but relatively close to the earth's surface in volcanically active regions. Earthquakes sometimes accompany volcanic eruptions as huge masses of magma move underground.
Nuclear bombs exploding underground cause small local earthquakes, which can be felt by people standing within a few miles of the test site. The earthquakes caused by nuclear bombs are tiny compared to natural earthquakes; but they have a distinctive "sound," and their location can be pinpointed. This is how nuclear weapons testing in one country can be monitored by other countries around the world.
Earth is covered by a crust of solid rock, which is broken into numerous plates that move around on the surface, bumping, overrunning, and pulling away from each other. One kind of boundary between rocks within a plate, as well as at the edges of the plates, is a fault. Faults are large-scale breaks in Earth's crust, in which the rock on one side of the fault has been moved relative to the rock on the other side of the fault by tectonic forces. Fault blocks are giant pieces of crust that are separated from the rocks around them by faults.
When the forces pushing on fault blocks cannot move one block past the other, potential energy is stored up in the fault zone. This is the same potential energy that resides in a giant boulder when it is poised, motionless, at the top of a steep slope. If something happens to overcome the friction holding the boulder in place, its potential energy will convert into kinetic energy as it thunders down the slope. In the fault zone, the potential energy builds up until the friction that sticks the fault blocks together is overcome. Then, in seconds, all the potential energy built up over the years turns to kinetic energy as the rocks surge past each other.
The vibrations of a fault block on the move can be detected by delicate instruments (seismometers and seismographs) in rocks on the other side of the world. Although this happens on a grand scale, it is remarkably like pushing on a stuck window or sliding door. Friction holds the window or door tight in its tracks. After enough force is applied to over-come the friction, the window or door jerks open.
Some fault blocks are stable and no longer experience the forces that moved them in the first place. The fault blocks that face each other across an active fault, however, are still influenced by tectonic forces in the ever-moving crust. They grind past each other along the fault as they move in different directions.
Fault blocks can move in a variety of ways, and these movements define the different types of faults. In a vertical fault, one block moves upward relative to the other. At the surface of the earth, a vertical fault forms a cliff, known as a fault scarp. The sheer eastern face of the Sierra Nevada mountain range is a fault scarp. In most vertical faults, the fault scarp is not truly vertical, and one of the fault blocks "hangs" over the other. This upper block is called the hanging wall and the lower block, the foot wall.
In horizontal faults, the blocks slide past one another without either block being lifted. In this case, the objects on the two sides of the fault simply slide past one another; for example, a road that straddles the fault might be offset by a number of feet. Complex faults display movements with both vertical and horizontal displacements.
Any one of the following fault types can generate an earthquake:
* Normal fault—A vertical fault in which the hanging wall moves down compared to the foot wall.
* Reverse fault—A vertical fault in which the hanging wall moves up in elevation relative to the foot wall.
* Thrust fault—A low-angle (less than 30°) reverse fault, similar to an inclined floor or ramp. The lower fault block is the ramp itself, and the upper fault block is gradually shoved up the ramp. The "ramp" may be shallow, steep, or even curved, but the motion of the upper fault block is always in an upward direction. A thrust fault caused the January 1994 Northridge earthquake near Los Angeles, California.
* Strike-slip (or transform) fault—A fault along which one fault block moves horizontally (sideways), past another fault block, like opposing lanes of traffic. The San Andreas fault in Northern California is one of the best known of this type.
When a falling rock splashes into a motionless pool of water , waves move out from the point of impact. These waves appear at the interface of water and air as circular ripples. However, the waves occur below the surface, too, traveling down into the water in a spherical pattern. In rock, as in water, a wave-causing event makes not one wave, but a number of waves, moving out from their source, one after another, like an expanding bubble.
Tectonic forces shift bodies of rock inside the earth, perhaps displacing a mountain range several feet in a few seconds, and they generate tremendous vibrations called seismic waves. The earthquake's focus (also called the hypocenter) is the point (usually deep in the subsurface) where the sudden sliding of one rock mass along a fault releases the stored potential energy of the fault zone. The first shock wave emerges at the surface at a point typically directly above the focus; this surface point is called the epicenter. Seismometers detect seismic waves that reach the surface. Seismographs (devices that record seismic phenomena) record the times of arrival for each group of vibrations on a seismogram (either a paper document or digital data).
Like surfaces in an echoing room that reflect or absorb sound, the boundaries of rock types within the earth change or block the direction of movement of seismic waves. Waves moving out from the earthquake's focus in an ever-expanding sphere become distorted, bent, and reflected. Seismologists (geologists who study seismic phenomena) analyze the distorted patterns made by seismic waves and search through the data for clues about the earth's internal structure.
Different kinds of earthquake-generated waves, moving at their own speeds, arrive at the surface in a particular order. The successive waves that arrive at a single site are called a wave train. Seismologists compare information about wave trains that are recorded as they pass through a number of data-collecting sites after an earthquake. By comparing data from three recording stations, they can pinpoint the map location (epicenter) and depth within the earth's surface (focus or hypocenter) of the earthquake.
These are the most important types of seismic waves:
* P-waves—The fastest waves, these compress or stretch the rock in their path through Earth, moving at about 4 mi (6.4 km) per second.
* S-waves—As they move through Earth, these waves shift the rock in their path up and down and side to side, moving at about 2 mi (3.2 km) per second.
* Rayleigh waves and Love waves—These two types of "surface waves" are named after seismologists. Moving at less than 2 mi (3.2 km) per second, they lag behind P-waves and S-waves but cause the most damage. Rayleigh waves cause the ground surface in their path to ripple with little waves. Love waves move in a zigzag along the ground and can wrench buildings from side to side.
The relative size of earthquakes is measured by the Richter scale , which measures the energy an earthquake releases. Each whole number increase in value on the Richter scale indicates a 10-fold increase in the energy released and a thirty-fold increase in ground motion. An earthquake measuring 8 on the Richter scale is ten times more powerful, therefore, than an earthquake with a Richter Magnitude of 7, which is ten times more powerful than an earthquake with a magnitude of 6. Another scale—the Modified Mercalli Scale uses observations of damage (like fallen chimneys) or people's assessments of effects (like mild or severe ground shaking) to describe the intensity of a quake.
Violent shaking changes water bearing sand into a liquid-like mass that will not support heavy loads, such as buildings. This phenomenon, called liquefaction, causes much of the destruction associated with an earthquake in liquefaction-prone areas. Downtown Mexico City rests on the old lakebed of Lake Texcoco, which is a large basin filled with liquefiable sand and ground water. In the Mexico City earthquake of 1985, the wet sand beneath tall buildings turned to slurry, as if the buildings stood on the surface of vibrating gelatin in a huge bowl. Most of the 10,000 people who died as a result of that earthquake were in buildings that collapsed as their foundations sank into liquefied sand.
In the sudden rearrangement of fault blocks in the earth's crust that cause an earthquake, the land surface on the dropped-down side of the fault can fall or subside in elevation by several feet. On a populated coastline, this can wipe out a city. Port Royal, on the south shore of Jamaica, subsided several feet in an earthquake in 1692 and suddenly disappeared as the sea rushed into the new depression. Eyewitnesses recounted the seismic destruction of the infamous pirate anchorage, as follows: "…in the space of three minutes, Port-Royall, the fairest town of all the English plantations, exceeding of its riches,…was shaken and shattered to pieces, sunk into and covered, for the greater part by the sea…The earth heaved and swelled like the rolling billows, and in many places the earth crack'd, open'd and shut, with a motion quick and fast…in some of these people were swallowed up, in others they were caught by the middle, and pressed to death…The whole was attended with…the noise of falling mountains at a distance, while the sky…was turned dull and reddish, like a glowing oven." Ships arriving later in the day found a small shattered remnant of the city that was still above the water. Charts of the Jamaican coast soon appeared printed with the words Port Royall Sunk.
In the New Madrid (Missouri) earthquake of 1811, a large area of land subsided around the bed of the Mississippi River in west Tennessee and Kentucky. The Mississippi was observed to flow backwards as it filled the new depression, to create what is now known as Reelfoot Lake.
Cities depend on networks of so-called "lifeline structures" to distribute water, power, and food and to remove sewage and waste. These networks, whether power lines, water mains, or roads, are easily damaged by earthquakes. Elevated freeways collapse readily, as demonstrated by a section of the San Francisco Bay Bridge in 1989 and the National Highway Number 2 in Kobe, Japan, in 1995. The combination of several networks breaking down at once multiplies the hazard to lives and property. Live power lines fall into water from broken water mains, creating a deadly electric shock hazard. Fires may start at ruptured gas mains or chemical storage tanks. Although emergency services are needed more than ever, many areas may not be accessible to fire trucks and other emergency vehicles. If the water mains are broken, there will be no pressure at the fire hydrants, and the firefighters' hoses are useless. The great fire that swept San Francisco in 1906 could not be stopped by regular firefighting methods. Only dynamiting entire blocks of buildings halted the fire's progress. Both Tokyo and Yokohama burned after the Kwanto earthquake struck Japan in 1923, and 143,000 people died, mostly in the fire.
Popular doomsayers excite uncomprehending fear by saying that earthquakes happen more frequently now than in earlier times. It is true that more people than ever are at risk from earthquakes, but this is because the world's population grows larger every year, and more people are living in earthquake-prone areas.
Today, sensitive seismometers "hear" every noteworthy earth-shaking event, recording it on a seismogram. Seismometers detect earthquake activity around the world, and data from all these instruments are available on the Internet within minutes of the earthquake. News agencies can report the event the same day. People have ready access to information about every earthquake that happens anywhere on Earth. And the earth experiences a lot of earthquakes—the planet never ceases to vibrate with tectonic forces, although the majority of them are not strong enough to be detected except with instruments. Earth has been resounding with earthquakes for more than 4 billion years. Earthquakes are a way of knowing that the planet beneath us is still experiencing normal operating conditions, full of heat and kinetic energy.
Ultrasensitive instruments placed across faults at the surface can measure the slow, almost imperceptible movement of fault blocks, which tell of great potential energy stored at the fault boundary. In some areas, foreshocks (small earthquakes that precede a larger event) may help seismologists predict the larger event. In other areas, where seismologists believe seismic activity should be occurring but is not, this seismic gap may be used instead to predict an inevitable large-scale earthquake.
Other instruments measure additional fault-zone phenomena that seem to be related to earthquakes. The rate at which radon gas issues from rocks near faults has been observed to change before an earthquake. The properties of the rocks themselves (such as their ability to conduct electricity ) have been observed to change, as the tectonic force exerted on them slowly alters the rocks of the fault zone between earthquakes. Peculiar animal behavior has been reported before many earthquakes, and research into this phenomenon is a legitimate area of scientific inquiry, even though no definite answers have been found.
Techniques of studying earthquakes from space are also being explored. Scientists have found that ground displacements cause waves in the air that travel into the ionosphere and disturb electron densities. By using the network of satellites and ground stations that are part of the global positioning system (GPS ), data about the ionosphere that is already being collected by these satellites can be used to understand the energy releases from earthquakes, which may help in their prediction.
Scientists have presumed that tides do not have any influence on or direct relationship to earthquakes. New studies show that tides may sometimes trigger earthquakes on faults where strain has been accumulating; tidal pull during new or full moons has been discounted by studies of over 13,000 earthquakes of which only 95 occurred during these episodes of tidal stress. Attention is also being directed toward the types of rock underlying areas of earthquake activity to see if rock types dampen (lessen the effects) or magnify earthquake motions.
Seismologists must make a hard choice when their data interpretations suggest an earthquake is about to happen. If they fail to warn people of danger they strongly suspect is imminent, many might die needlessly. But, if people are evacuated from a potentially dangerous area and no earthquake occurs, the public will lose confidence in such warnings and might not heed them the next time.
As more is discovered about how and why earthquakes occur, that knowledge can be used to prevent the conditions that allow earthquakes to cause harm. The most effective way to minimize the hazards of earthquakes is to build new buildings or retrofit old ones to withstand the short, high-speed acceleration of earthquake shocks.
"Earthquake." World of Earth Science. 2003. Retrieved March 20, 2011 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437800186.html
Earthquake
An earthquake is a geological event inside the earth that generates strong vibrations. When the vibrations reach the surface, the earth shakes, often causing damage to natural and man-made objects, and sometimes killing and injuring people and destroying their property. Earthquakes can occur for a variety of reasons; however, the most common source of earthquakes is movement along a fault.
Some earthquakes occur when tectonic plates, large sections of Earth's crust and upper mantle, move past each other. Earthquakes along the San Andreas and Hayward faults in California occur because of this. Earthquakes also occur if one plate overruns another, as on the western coast of South America , the northwest coast of North America , and in Japan. If plates collide but neither is overrun, as they do crossing Europe and Asia from Spain to Vietnam, earthquakes result as the rocks at the abutting plates compress into high mountain ranges. In all three of these settings, earthquakes result from movement along faults.
A fault block may also move due to gravity , sinking between other fault blocks that surround and support it. Sinking fault blocks and the mountains that surround them form a distinctive topography of basins and mountain ranges. This type of fault block configuration is typified by the North American Basin and Range topographic province. In such places, elevation losses by the valleys as they sink between the mountains are accompanied by tremors or earthquakes. Another kind of mountain range rises because of an active thrust fault. Tectonic compression (tectonic, meaning having to do with the forces that deform the rocks of planets) shoves the range up the active thrust fault, which acts like a natural ramp.
Molten rock called magma moves beneath but relatively close to the earth's surface in volcanically active regions. Earthquakes sometimes accompany volcanic eruptions as huge masses of magma move underground.
Nuclear bombs exploding underground cause small local earthquakes, which can be felt by people standing within a few miles of the test site. The earthquakes caused by nuclear bombs are tiny compared to natural earthquakes; but they have a distinctive "sound," and their location can be pinpointed. This is how nuclear weapons testing in one country can be monitored by other countries around the world.
Earth is covered by a crust of solid rock, which is broken into numerous plates that move around on the surface, bumping, overrunning, and pulling away from each other. One kind of boundary between rocks within a plate, as well as at the edges of the plates, is a fault. Faults are large-scale breaks in Earth's crust, in which the rock on one side of the fault has been moved relative to the rock on the other side of the fault by tectonic forces. Fault blocks are giant pieces of crust that are separated from the rocks around them by faults.
When the forces pushing on fault blocks cannot move one block past the other, potential energy is stored up in the fault zone. This is the same potential energy that resides in a giant boulder when it is poised, motionless, at the top of a steep slope. If something happens to overcome the friction holding the boulder in place, its potential energy will convert into kinetic energy as it thunders down the slope. In the fault zone, the potential energy builds up until the friction that sticks the fault blocks together is overcome. Then, in seconds, all the potential energy built up over the years turns to kinetic energy as the rocks surge past each other.
The vibrations of a fault block on the move can be detected by delicate instruments (seismometers and seismographs) in rocks on the other side of the world. Although this happens on a grand scale, it is remarkably like pushing on a stuck window or sliding door. Friction holds the window or door tight in its tracks. After enough force is applied to over-come the friction, the window or door jerks open.
Some fault blocks are stable and no longer experience the forces that moved them in the first place. The fault blocks that face each other across an active fault, however, are still influenced by tectonic forces in the ever-moving crust. They grind past each other along the fault as they move in different directions.
Fault blocks can move in a variety of ways, and these movements define the different types of faults. In a vertical fault, one block moves upward relative to the other. At the surface of the earth, a vertical fault forms a cliff, known as a fault scarp. The sheer eastern face of the Sierra Nevada mountain range is a fault scarp. In most vertical faults, the fault scarp is not truly vertical, and one of the fault blocks "hangs" over the other. This upper block is called the hanging wall and the lower block, the foot wall.
In horizontal faults, the blocks slide past one another without either block being lifted. In this case, the objects on the two sides of the fault simply slide past one another; for example, a road that straddles the fault might be offset by a number of feet. Complex faults display movements with both vertical and horizontal displacements.
Any one of the following fault types can generate an earthquake:
* Normal fault—A vertical fault in which the hanging wall moves down compared to the foot wall.
* Reverse fault—A vertical fault in which the hanging wall moves up in elevation relative to the foot wall.
* Thrust fault—A low-angle (less than 30°) reverse fault, similar to an inclined floor or ramp. The lower fault block is the ramp itself, and the upper fault block is gradually shoved up the ramp. The "ramp" may be shallow, steep, or even curved, but the motion of the upper fault block is always in an upward direction. A thrust fault caused the January 1994 Northridge earthquake near Los Angeles, California.
* Strike-slip (or transform) fault—A fault along which one fault block moves horizontally (sideways), past another fault block, like opposing lanes of traffic. The San Andreas fault in Northern California is one of the best known of this type.
When a falling rock splashes into a motionless pool of water , waves move out from the point of impact. These waves appear at the interface of water and air as circular ripples. However, the waves occur below the surface, too, traveling down into the water in a spherical pattern. In rock, as in water, a wave-causing event makes not one wave, but a number of waves, moving out from their source, one after another, like an expanding bubble.
Tectonic forces shift bodies of rock inside the earth, perhaps displacing a mountain range several feet in a few seconds, and they generate tremendous vibrations called seismic waves. The earthquake's focus (also called the hypocenter) is the point (usually deep in the subsurface) where the sudden sliding of one rock mass along a fault releases the stored potential energy of the fault zone. The first shock wave emerges at the surface at a point typically directly above the focus; this surface point is called the epicenter. Seismometers detect seismic waves that reach the surface. Seismographs (devices that record seismic phenomena) record the times of arrival for each group of vibrations on a seismogram (either a paper document or digital data).
Like surfaces in an echoing room that reflect or absorb sound, the boundaries of rock types within the earth change or block the direction of movement of seismic waves. Waves moving out from the earthquake's focus in an ever-expanding sphere become distorted, bent, and reflected. Seismologists (geologists who study seismic phenomena) analyze the distorted patterns made by seismic waves and search through the data for clues about the earth's internal structure.
Different kinds of earthquake-generated waves, moving at their own speeds, arrive at the surface in a particular order. The successive waves that arrive at a single site are called a wave train. Seismologists compare information about wave trains that are recorded as they pass through a number of data-collecting sites after an earthquake. By comparing data from three recording stations, they can pinpoint the map location (epicenter) and depth within the earth's surface (focus or hypocenter) of the earthquake.
These are the most important types of seismic waves:
* P-waves—The fastest waves, these compress or stretch the rock in their path through Earth, moving at about 4 mi (6.4 km) per second.
* S-waves—As they move through Earth, these waves shift the rock in their path up and down and side to side, moving at about 2 mi (3.2 km) per second.
* Rayleigh waves and Love waves—These two types of "surface waves" are named after seismologists. Moving at less than 2 mi (3.2 km) per second, they lag behind P-waves and S-waves but cause the most damage. Rayleigh waves cause the ground surface in their path to ripple with little waves. Love waves move in a zigzag along the ground and can wrench buildings from side to side.
The relative size of earthquakes is measured by the Richter scale , which measures the energy an earthquake releases. Each whole number increase in value on the Richter scale indicates a 10-fold increase in the energy released and a thirty-fold increase in ground motion. An earthquake measuring 8 on the Richter scale is ten times more powerful, therefore, than an earthquake with a Richter Magnitude of 7, which is ten times more powerful than an earthquake with a magnitude of 6. Another scale—the Modified Mercalli Scale uses observations of damage (like fallen chimneys) or people's assessments of effects (like mild or severe ground shaking) to describe the intensity of a quake.
Violent shaking changes water bearing sand into a liquid-like mass that will not support heavy loads, such as buildings. This phenomenon, called liquefaction, causes much of the destruction associated with an earthquake in liquefaction-prone areas. Downtown Mexico City rests on the old lakebed of Lake Texcoco, which is a large basin filled with liquefiable sand and ground water. In the Mexico City earthquake of 1985, the wet sand beneath tall buildings turned to slurry, as if the buildings stood on the surface of vibrating gelatin in a huge bowl. Most of the 10,000 people who died as a result of that earthquake were in buildings that collapsed as their foundations sank into liquefied sand.
In the sudden rearrangement of fault blocks in the earth's crust that cause an earthquake, the land surface on the dropped-down side of the fault can fall or subside in elevation by several feet. On a populated coastline, this can wipe out a city. Port Royal, on the south shore of Jamaica, subsided several feet in an earthquake in 1692 and suddenly disappeared as the sea rushed into the new depression. Eyewitnesses recounted the seismic destruction of the infamous pirate anchorage, as follows: "…in the space of three minutes, Port-Royall, the fairest town of all the English plantations, exceeding of its riches,…was shaken and shattered to pieces, sunk into and covered, for the greater part by the sea…The earth heaved and swelled like the rolling billows, and in many places the earth crack'd, open'd and shut, with a motion quick and fast…in some of these people were swallowed up, in others they were caught by the middle, and pressed to death…The whole was attended with…the noise of falling mountains at a distance, while the sky…was turned dull and reddish, like a glowing oven." Ships arriving later in the day found a small shattered remnant of the city that was still above the water. Charts of the Jamaican coast soon appeared printed with the words Port Royall Sunk.
In the New Madrid (Missouri) earthquake of 1811, a large area of land subsided around the bed of the Mississippi River in west Tennessee and Kentucky. The Mississippi was observed to flow backwards as it filled the new depression, to create what is now known as Reelfoot Lake.
Cities depend on networks of so-called "lifeline structures" to distribute water, power, and food and to remove sewage and waste. These networks, whether power lines, water mains, or roads, are easily damaged by earthquakes. Elevated freeways collapse readily, as demonstrated by a section of the San Francisco Bay Bridge in 1989 and the National Highway Number 2 in Kobe, Japan, in 1995. The combination of several networks breaking down at once multiplies the hazard to lives and property. Live power lines fall into water from broken water mains, creating a deadly electric shock hazard. Fires may start at ruptured gas mains or chemical storage tanks. Although emergency services are needed more than ever, many areas may not be accessible to fire trucks and other emergency vehicles. If the water mains are broken, there will be no pressure at the fire hydrants, and the firefighters' hoses are useless. The great fire that swept San Francisco in 1906 could not be stopped by regular firefighting methods. Only dynamiting entire blocks of buildings halted the fire's progress. Both Tokyo and Yokohama burned after the Kwanto earthquake struck Japan in 1923, and 143,000 people died, mostly in the fire.
Popular doomsayers excite uncomprehending fear by saying that earthquakes happen more frequently now than in earlier times. It is true that more people than ever are at risk from earthquakes, but this is because the world's population grows larger every year, and more people are living in earthquake-prone areas.
Today, sensitive seismometers "hear" every noteworthy earth-shaking event, recording it on a seismogram. Seismometers detect earthquake activity around the world, and data from all these instruments are available on the Internet within minutes of the earthquake. News agencies can report the event the same day. People have ready access to information about every earthquake that happens anywhere on Earth. And the earth experiences a lot of earthquakes—the planet never ceases to vibrate with tectonic forces, although the majority of them are not strong enough to be detected except with instruments. Earth has been resounding with earthquakes for more than 4 billion years. Earthquakes are a way of knowing that the planet beneath us is still experiencing normal operating conditions, full of heat and kinetic energy.
Ultrasensitive instruments placed across faults at the surface can measure the slow, almost imperceptible movement of fault blocks, which tell of great potential energy stored at the fault boundary. In some areas, foreshocks (small earthquakes that precede a larger event) may help seismologists predict the larger event. In other areas, where seismologists believe seismic activity should be occurring but is not, this seismic gap may be used instead to predict an inevitable large-scale earthquake.
Other instruments measure additional fault-zone phenomena that seem to be related to earthquakes. The rate at which radon gas issues from rocks near faults has been observed to change before an earthquake. The properties of the rocks themselves (such as their ability to conduct electricity ) have been observed to change, as the tectonic force exerted on them slowly alters the rocks of the fault zone between earthquakes. Peculiar animal behavior has been reported before many earthquakes, and research into this phenomenon is a legitimate area of scientific inquiry, even though no definite answers have been found.
Techniques of studying earthquakes from space are also being explored. Scientists have found that ground displacements cause waves in the air that travel into the ionosphere and disturb electron densities. By using the network of satellites and ground stations that are part of the global positioning system (GPS ), data about the ionosphere that is already being collected by these satellites can be used to understand the energy releases from earthquakes, which may help in their prediction.
Scientists have presumed that tides do not have any influence on or direct relationship to earthquakes. New studies show that tides may sometimes trigger earthquakes on faults where strain has been accumulating; tidal pull during new or full moons has been discounted by studies of over 13,000 earthquakes of which only 95 occurred during these episodes of tidal stress. Attention is also being directed toward the types of rock underlying areas of earthquake activity to see if rock types dampen (lessen the effects) or magnify earthquake motions.
Seismologists must make a hard choice when their data interpretations suggest an earthquake is about to happen. If they fail to warn people of danger they strongly suspect is imminent, many might die needlessly. But, if people are evacuated from a potentially dangerous area and no earthquake occurs, the public will lose confidence in such warnings and might not heed them the next time.
As more is discovered about how and why earthquakes occur, that knowledge can be used to prevent the conditions that allow earthquakes to cause harm. The most effective way to minimize the hazards of earthquakes is to build new buildings or retrofit old ones to withstand the short, high-speed acceleration of earthquake shocks.
"Earthquake." World of Earth Science. 2003. Retrieved March 20, 2011 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437800186.html
WHAT TO DO
BEFORE, DURING AND AFTER
EARTHQUAKES
BEFORE
The key to effective disaster prevention is planning.
Determine whether the site is along an active fault and/or prone to liquefaction or landslide which may cause damage to your house or building.
Be sure that proper structural design and engineering practice is followed when constructing a house or building.
Evaluate the structural soundness of buildings and important infrastructures; strengthen or retrofit if necessary.
Prepare your place of work and residence for the event.
Strap heavy furniture/cabinets to the wall to prevent sliding or toppling.
Breakable items, harmful chemicals and flammable materials should be stored in the lowermost shelves and secured firmly.
Make a habit to turn off gas tanks when not in use.
Familiarize yourself with your place of work and residence.
Identify relatively strong parts of the building like door jambs, near elevator shafts, sturdy tables, where you can take refuge during an earthquake.
Learn to use fire extinguishers, first aid kits, alarms and emergency exits. These should be accessible, conveniently located and prominently marked.
Most causes of injuries during earthquakes are from falling objects.
Heavy materials should be kept in lower shelves.
Check the stability of hanging objects which may break loose and fall during earthquakes.
Prepare and maintain an earthquake survival kit consisting of a battery-powered radio, flashlight, first aid kit, potable water, candies, ready-to-eat food, whistle and dust mask.
DURING
If you are inside a structurally sound building, stay there!
Protect your body from falling debris by bracing yourself in a doorway or by getting under a sturdy table or desk.
If you are outside, move to an open area.
Get away from power lines, posts, walls and other structures that may fall or collapse.
Stay away from buildings with glass panes.
When driving a vehicle, pull to the side of the road and stop.
Do not attempt to cross bridges or overpasses which may have been damaged.
If you are on a mountain or near a steep hillside, move away from steep escarpments that may be affected by landslides.
If you are along the shore and you feel a very strong earthquake, strong enough to make standing difficult, it is always safest to assume that a tsunami (giant sea waves) has been triggered. Run away from the shore toward higher ground.
AFTER
If you are inside an old structure, take the fastest and safest way out!
Do not rush to the exit; get out calmly in an orderly manner.
Do not use elevators, use the stairs.
Check yourself and others for injuries.
Unless you need emergency help:
Do not use your telephone to call relatives and friends. Disaster prevention authorities may need the lines for emergency communications.
Do not use your car and drive around areas of damage. Rescue and relief operations need the road for mobility.
Help reduce the casualties from the earthquake:
Don’t enter partially damaged buildings. Strong aftershocks may cause them to collapse.
Gather information and disaster prevention instructions from battery-operated radios.
Obey public safety precautions.
Check your surroundings
Clean up chemical spills, toxic and flammable materials to avoid any chain of unwanted events. Check for fire and if any, have it controlled.
Check your water and electrical lines for defects. If any damage is suspected, turn the system off in the main valve or switch.
If you must evacuate your residence, leave a message stating where you are going.
Take with you your earthquake survival kit, which should contain all necessary items for your protection and comfort.
http://images.gmanews.tv/html/earthquake.htm
BEFORE, DURING AND AFTER
EARTHQUAKES
BEFORE
The key to effective disaster prevention is planning.
Determine whether the site is along an active fault and/or prone to liquefaction or landslide which may cause damage to your house or building.
Be sure that proper structural design and engineering practice is followed when constructing a house or building.
Evaluate the structural soundness of buildings and important infrastructures; strengthen or retrofit if necessary.
Prepare your place of work and residence for the event.
Strap heavy furniture/cabinets to the wall to prevent sliding or toppling.
Breakable items, harmful chemicals and flammable materials should be stored in the lowermost shelves and secured firmly.
Make a habit to turn off gas tanks when not in use.
Familiarize yourself with your place of work and residence.
Identify relatively strong parts of the building like door jambs, near elevator shafts, sturdy tables, where you can take refuge during an earthquake.
Learn to use fire extinguishers, first aid kits, alarms and emergency exits. These should be accessible, conveniently located and prominently marked.
Most causes of injuries during earthquakes are from falling objects.
Heavy materials should be kept in lower shelves.
Check the stability of hanging objects which may break loose and fall during earthquakes.
Prepare and maintain an earthquake survival kit consisting of a battery-powered radio, flashlight, first aid kit, potable water, candies, ready-to-eat food, whistle and dust mask.
DURING
If you are inside a structurally sound building, stay there!
Protect your body from falling debris by bracing yourself in a doorway or by getting under a sturdy table or desk.
If you are outside, move to an open area.
Get away from power lines, posts, walls and other structures that may fall or collapse.
Stay away from buildings with glass panes.
When driving a vehicle, pull to the side of the road and stop.
Do not attempt to cross bridges or overpasses which may have been damaged.
If you are on a mountain or near a steep hillside, move away from steep escarpments that may be affected by landslides.
If you are along the shore and you feel a very strong earthquake, strong enough to make standing difficult, it is always safest to assume that a tsunami (giant sea waves) has been triggered. Run away from the shore toward higher ground.
AFTER
If you are inside an old structure, take the fastest and safest way out!
Do not rush to the exit; get out calmly in an orderly manner.
Do not use elevators, use the stairs.
Check yourself and others for injuries.
Unless you need emergency help:
Do not use your telephone to call relatives and friends. Disaster prevention authorities may need the lines for emergency communications.
Do not use your car and drive around areas of damage. Rescue and relief operations need the road for mobility.
Help reduce the casualties from the earthquake:
Don’t enter partially damaged buildings. Strong aftershocks may cause them to collapse.
Gather information and disaster prevention instructions from battery-operated radios.
Obey public safety precautions.
Check your surroundings
Clean up chemical spills, toxic and flammable materials to avoid any chain of unwanted events. Check for fire and if any, have it controlled.
Check your water and electrical lines for defects. If any damage is suspected, turn the system off in the main valve or switch.
If you must evacuate your residence, leave a message stating where you are going.
Take with you your earthquake survival kit, which should contain all necessary items for your protection and comfort.
http://images.gmanews.tv/html/earthquake.htm
Thursday, March 17, 2011
Midnight sun
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the south of the Arctic Circle, and south and nearby to the north of the Antarctic Circle where the sun remains visible at the local midnight. Given fair weather, the sun is visible for a continuous 24 hours, mostly north of the Arctic Circle and south of the Antarctic Circle. The number of days per year with potential midnight sun increases the farther poleward one goes.
There are no permanent human settlements south of the Antarctic Circle, so the countries and territories whose populations experience it are limited to the ones crossed by the Arctic Circle, e.g.. Canada (Yukon, Northwest Territories, and Nunavut), United States of America (Alaska), Denmark (Greenland), Norway, Sweden, Finland, Russia, and extremities of Iceland. A quarter of Finland's territory lies north of the Arctic Circle and at the country's northernmost point the sun does not set for 73 days during summer. In Svalbard, Norway, the northernmost inhabited region of Europe, there is no sunset from approximately 19 April to 23 August. The extreme sites are the poles where the sun can be continuously visible for a half year.
The opposite phenomenon, polar night, occurs in winter when the sun stays below the horizon throughout the day.
Since the Earth's axis is tilted with respect to the ecliptic by approximately 23 degrees 27 minutes, the sun does not set at high latitudes in (local) summer. The duration of the midnight sun increases from one day during the summer solstice at the polar circle to approximately six months at the poles. At extreme latitudes, it is usually referred to as polar day. The length of the time the sun is above the horizon varies from couple of days at the Arctic Circle and Antarctic Circle to 186 days at the poles.
At the poles themselves, the sun only rises once and sets once, each year. During the six months when the sun is above the horizon at the poles, the sun spends the days constantly moving around the horizon, reaching its highest circuit of the sky at the summer solstice.
Due to refraction, the midnight sun may be experienced at latitudes slightly below the polar circle, though not exceeding one degree (depending on local conditions). For example, it is possible to experience the midnight sun in Iceland, even though most of it (Grímsey being a notable exception) is slightly south of the Arctic Circle. Even the northern extremities of Scotland (and those places on similar latitudes) experience a permanent "dusk" or glare in the northern skies at these times.
Time zones and daylight saving time
For purposes of this article, the term "midnight sun" refers to the phenomena of 24 consecutive hours of sunlight north of the Arctic Circle or south of the Antarctic Circle. There are, however, some instances which are sometimes referred to as "midnight sun", even though they are in reality due to meandering time zones and the observance of daylight saving time. For instance, in Fairbanks, Alaska, which is located south of the Arctic Circle, the sun sets at 12:47 a.m. on the Summer Solstice. This is because Fairbanks is one hour ahead of its idealized time zone (due to meandering for the purpose of keeping most of the state on one time zone) and because the state of Alaska observes daylight saving time. This means that solar culmination occurs at roughly 2 p.m. instead of at 12 noon, as in most places. Conversely, astronomical midnight occurs at 2 a.m. In Bethel, which is further south than Anchorage, the sun sets on the Summer Solstice at 12:24 a.m. for the same reasons. These examples are not true midnight sun phenomena, however, since the sun is below the horizon on every day of the year at the local astronomical midnight.
White Nights
Locations above 60 degrees latitude that is south of the Arctic Circle or north of the Antarctic Circle experience midnight twilight instead. The sun is at the horizon to 6 degrees below the horizon, so that daytime activities, such as reading, are still possible without artificial light, if it is not cloudy.
White Nights have become a common symbol of Saint Petersburg, Russia, where they occur from about 11 June to 2 July, and the last 10 days of June are celebrated with cultural events.
When to see the midnight sun
According to Visit Norway the midnight sun is visible at the Arctic Circle from June 12 until July 1. The further north one goes the longer this period extends.
At North Cape, Norway, known as the northernmost point of Continental Europe this period extends approximately from May 14 to July 29. On the Svalbard archipelago further north this period extends from April 20 to August 22.
Effect on people
Many find it difficult to fall asleep during the night when the sun is shining. In general, visitors and newcomers are most affected. Some natives are also affected, but in general to a lesser degree. The effect of the midnight sun, that is, not experiencing night for long durations of time, is said to cause hypomania, which is characterized by persistent and pervasive elevated or irritable mood.
ADHD symptoms could be caused by this, changing attention spans for people that have to rush through the little daylight at night and the irritability and hyperactivity of continuous sunlight.
The midnight sun also poses special challenges to religious people such as Jewish people who have religious rites based around the 24 hour day/night cycle. In the Jewish community this has given rise to a body of Jewish law in the Polar Regions, which attempts to deal with the special challenges of adhering to the Mitzvah in such conditions.
http://en.wikipedia.org/wiki/Midnight_sun
The midnight sun is a natural phenomenon occurring in summer months at latitudes north and nearby to the south of the Arctic Circle, and south and nearby to the north of the Antarctic Circle where the sun remains visible at the local midnight. Given fair weather, the sun is visible for a continuous 24 hours, mostly north of the Arctic Circle and south of the Antarctic Circle. The number of days per year with potential midnight sun increases the farther poleward one goes.
There are no permanent human settlements south of the Antarctic Circle, so the countries and territories whose populations experience it are limited to the ones crossed by the Arctic Circle, e.g.. Canada (Yukon, Northwest Territories, and Nunavut), United States of America (Alaska), Denmark (Greenland), Norway, Sweden, Finland, Russia, and extremities of Iceland. A quarter of Finland's territory lies north of the Arctic Circle and at the country's northernmost point the sun does not set for 73 days during summer. In Svalbard, Norway, the northernmost inhabited region of Europe, there is no sunset from approximately 19 April to 23 August. The extreme sites are the poles where the sun can be continuously visible for a half year.
The opposite phenomenon, polar night, occurs in winter when the sun stays below the horizon throughout the day.
Since the Earth's axis is tilted with respect to the ecliptic by approximately 23 degrees 27 minutes, the sun does not set at high latitudes in (local) summer. The duration of the midnight sun increases from one day during the summer solstice at the polar circle to approximately six months at the poles. At extreme latitudes, it is usually referred to as polar day. The length of the time the sun is above the horizon varies from couple of days at the Arctic Circle and Antarctic Circle to 186 days at the poles.
At the poles themselves, the sun only rises once and sets once, each year. During the six months when the sun is above the horizon at the poles, the sun spends the days constantly moving around the horizon, reaching its highest circuit of the sky at the summer solstice.
Due to refraction, the midnight sun may be experienced at latitudes slightly below the polar circle, though not exceeding one degree (depending on local conditions). For example, it is possible to experience the midnight sun in Iceland, even though most of it (Grímsey being a notable exception) is slightly south of the Arctic Circle. Even the northern extremities of Scotland (and those places on similar latitudes) experience a permanent "dusk" or glare in the northern skies at these times.
Time zones and daylight saving time
For purposes of this article, the term "midnight sun" refers to the phenomena of 24 consecutive hours of sunlight north of the Arctic Circle or south of the Antarctic Circle. There are, however, some instances which are sometimes referred to as "midnight sun", even though they are in reality due to meandering time zones and the observance of daylight saving time. For instance, in Fairbanks, Alaska, which is located south of the Arctic Circle, the sun sets at 12:47 a.m. on the Summer Solstice. This is because Fairbanks is one hour ahead of its idealized time zone (due to meandering for the purpose of keeping most of the state on one time zone) and because the state of Alaska observes daylight saving time. This means that solar culmination occurs at roughly 2 p.m. instead of at 12 noon, as in most places. Conversely, astronomical midnight occurs at 2 a.m. In Bethel, which is further south than Anchorage, the sun sets on the Summer Solstice at 12:24 a.m. for the same reasons. These examples are not true midnight sun phenomena, however, since the sun is below the horizon on every day of the year at the local astronomical midnight.
White Nights
Locations above 60 degrees latitude that is south of the Arctic Circle or north of the Antarctic Circle experience midnight twilight instead. The sun is at the horizon to 6 degrees below the horizon, so that daytime activities, such as reading, are still possible without artificial light, if it is not cloudy.
White Nights have become a common symbol of Saint Petersburg, Russia, where they occur from about 11 June to 2 July, and the last 10 days of June are celebrated with cultural events.
When to see the midnight sun
According to Visit Norway the midnight sun is visible at the Arctic Circle from June 12 until July 1. The further north one goes the longer this period extends.
At North Cape, Norway, known as the northernmost point of Continental Europe this period extends approximately from May 14 to July 29. On the Svalbard archipelago further north this period extends from April 20 to August 22.
Effect on people
Many find it difficult to fall asleep during the night when the sun is shining. In general, visitors and newcomers are most affected. Some natives are also affected, but in general to a lesser degree. The effect of the midnight sun, that is, not experiencing night for long durations of time, is said to cause hypomania, which is characterized by persistent and pervasive elevated or irritable mood.
ADHD symptoms could be caused by this, changing attention spans for people that have to rush through the little daylight at night and the irritability and hyperactivity of continuous sunlight.
The midnight sun also poses special challenges to religious people such as Jewish people who have religious rites based around the 24 hour day/night cycle. In the Jewish community this has given rise to a body of Jewish law in the Polar Regions, which attempts to deal with the special challenges of adhering to the Mitzvah in such conditions.
http://en.wikipedia.org/wiki/Midnight_sun
Supermoon
In astrology, a supermoon is a full or new moon that coincides with a close approach by the Moon to the Earth. The Moon's distance varies each month between approximately 354,000 km (220,000 mi) and 410,000 km (254,000 mi).
Definition
The term supermoon was coined by astrologer Richard Nolle in 1979, defined as
“ ...a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit (perigee). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth. ”
The term supermoon is not widely accepted or used within the astronomy or scientific community, who prefer the term perigee-syzygy.
Effect on tides
The combined effect of the Sun and Moon on Earth's oceans, the tide, is greatest when the Moon is new or full. Full Moons during lunar perigees (such as in the case of supermoons) exert an even stronger tidal force, resulting in more extreme high and low tides, but even at their most powerful this force is still considerably weak.
Link to natural disasters
Speculations of a link between the occurrence of supermoons and natural disasters such as earthquakes and tsunami are extremely tenuous. Arguments have been made that natural disasters coinciding with years in which supermoons occurred were influenced by the Moon's increased gravitational strength, though because of the monthly alternation between lunar apogee and perigee such an argument cannot be supported unless the disaster in question falls on the actual date of the supermoon.
It has been argued that the Indian Ocean tsunami and earthquake on December 26, 2004, was influenced by a supermoon which occurred 2 weeks later on January 10, 2005. However two weeks before a supermoon the Moon is at the opposite point in its orbit: its apogee (greatest distance). Thus a supermoon effect is impossible.
Most recently, astrologers argued that the Tōhoku earthquake and tsunami that hit Japan on March 11, 2011, was influenced by the March 19 supermoon, the closest supermoon since 1992. The problem with this claim is that on March 11 the Moon was actually closer to apogee than perigee, at approximately 400,000 km (240,000 mi) from the Earth, which is further than the average distance between the Moon and the Earth throughout the Moon's orbital cycle.
While some studies have reported a weak correlation between shallow, very low intensity earthquakes and lunar activity, there is no empirical evidence of any correlation with major earthquakes.
Dates of supermoons between 1950 and 2050
There are approximately 4-6 supermoons annually. The following is a list of past and predicted extreme supermoons.
• November 10, 1954
• November 20, 1972
• January 8, 1974
• February 26, 1975
• December 2nd, 1990
• January 19, 1992
• March 8, 1993
• January 10, 2005
• December 12, 2008
• January 30, 2010
• March 19, 2011
• November 14, 2016
• January 2nd, 2018
• January 21st, 2023
• November 25, 2034
• January 13, 2036
http://en.wikipedia.org/wiki/Supermoon
In astrology, a supermoon is a full or new moon that coincides with a close approach by the Moon to the Earth. The Moon's distance varies each month between approximately 354,000 km (220,000 mi) and 410,000 km (254,000 mi).
Definition
The term supermoon was coined by astrologer Richard Nolle in 1979, defined as
“ ...a new or full moon which occurs with the Moon at or near (within 90% of) its closest approach to Earth in a given orbit (perigee). In short, Earth, Moon and Sun are all in a line, with Moon in its nearest approach to Earth. ”
The term supermoon is not widely accepted or used within the astronomy or scientific community, who prefer the term perigee-syzygy.
Effect on tides
The combined effect of the Sun and Moon on Earth's oceans, the tide, is greatest when the Moon is new or full. Full Moons during lunar perigees (such as in the case of supermoons) exert an even stronger tidal force, resulting in more extreme high and low tides, but even at their most powerful this force is still considerably weak.
Link to natural disasters
Speculations of a link between the occurrence of supermoons and natural disasters such as earthquakes and tsunami are extremely tenuous. Arguments have been made that natural disasters coinciding with years in which supermoons occurred were influenced by the Moon's increased gravitational strength, though because of the monthly alternation between lunar apogee and perigee such an argument cannot be supported unless the disaster in question falls on the actual date of the supermoon.
It has been argued that the Indian Ocean tsunami and earthquake on December 26, 2004, was influenced by a supermoon which occurred 2 weeks later on January 10, 2005. However two weeks before a supermoon the Moon is at the opposite point in its orbit: its apogee (greatest distance). Thus a supermoon effect is impossible.
Most recently, astrologers argued that the Tōhoku earthquake and tsunami that hit Japan on March 11, 2011, was influenced by the March 19 supermoon, the closest supermoon since 1992. The problem with this claim is that on March 11 the Moon was actually closer to apogee than perigee, at approximately 400,000 km (240,000 mi) from the Earth, which is further than the average distance between the Moon and the Earth throughout the Moon's orbital cycle.
While some studies have reported a weak correlation between shallow, very low intensity earthquakes and lunar activity, there is no empirical evidence of any correlation with major earthquakes.
Dates of supermoons between 1950 and 2050
There are approximately 4-6 supermoons annually. The following is a list of past and predicted extreme supermoons.
• November 10, 1954
• November 20, 1972
• January 8, 1974
• February 26, 1975
• December 2nd, 1990
• January 19, 1992
• March 8, 1993
• January 10, 2005
• December 12, 2008
• January 30, 2010
• March 19, 2011
• November 14, 2016
• January 2nd, 2018
• January 21st, 2023
• November 25, 2034
• January 13, 2036
http://en.wikipedia.org/wiki/Supermoon
Wednesday, March 16, 2011
THE PHILIPPINE PUBLIC STORM WARNING SIGNALS
PSWS # 1
METEOROLOGICAL CONDITIONS:
* A tropical cyclone will affect the locality.
* Winds of 30-60 kph may be expected in at least 36 hours or intermittent rains may be expected within 36 hours. (When the tropical cyclone develops very close to the locality a shorter lead time of the occurrence of the winds will be specified in the warning bulletin.)
IMPACT OF THE WINDS:
* Twigs and branches of small trees may be broken.
* Some banana plants may be tilted or downed.
* Some houses of very light materials (nipa and cogon) may be partially unroofed.
* Unless this warning signal is upgraded during the entire existence of the tropical cyclone, only very light or no damage at all may be sustained by the exposed communities.
* Rice crop, however, may suffer significant damage when it is in its flowering stage.
PRECAUTIONARY MEASURES:
* When the tropical cyclone is strong or is intensifying and is moving closer, this signal may be upgraded to the next higher level.
* The waves on coastal waters may gradually develop and become bigger and higher.
* The people are advised to listen to the latest severe weather bulletin issued by PAGASA every six hours. In the meantime, business may be carried out as usual except when flood occur.
* Disaster preparedness is activated to alert status.
PSWS # 2
METEOROLOGICAL CONDITIONS:
* A tropical cyclone will affect the the locality.
* Winds of greater than 60 kph and up to 100 kph may be expected in at least 24 hours.
IMPACT OF THE WINDS:
* Some coconut trees may be tilted with few others broken.
* Few big trees may be uprooted.
* Many banana plants may be downed.
* Rice and corn may be adversely affected.
* Large number of nipa and cogon houses may be partially or totally unroofed.
* Some old galvanized iron roofings may be peeled off.
* In general, the winds may bring light to moderate damage to the exposed communities.
PRECAUTIONARY MEASURES:
* The sea and coastal waters are dangerous to small sea crafts
* Special attention should be given to the latest position, the direction and speed of movement and the intensity of the storm as it may intensify and move towards the locality.
* The general public especially people traveling by sea and air are cautioned to avoid unnecessary risks.
* Outdoor activities of children should be postponed.
* Secure properties before the signal is upgraded.
* Disaster preparedness agencies / organizations are in action to alert their communities.
PSWS # 3
METEOROLOGICAL CONDITIONS:
* A tropical cyclone will affect the locality.
* Winds of greater than 100 kph up to 185 kph may be expected in at least 18 hours.
IMPACT OF THE WINDS:
* Many coconut trees may be broken or destroyed.
* Almost all banana plants may be downed and a large number of trees may be uprooted.
* Rice and corn crops may suffer heavy losses.
* Majority of all nipa and cogon houses may be unroofed or destroyed and there may be considerable damage to structures of light to medium construction.
* There may be widespread disruption of electrical power and communication services.
* In general, moderate to heavy damage may be experienced, particularly in the agricultural and industrial sectors.
PRECAUTIONARY MEASURES:
* The disturbance is dangerous to the communities threatened/affected.
* The sea and coastal waters will be very dangerous to all seacrafts.
* Travel is very risky especially by sea and air.
* People are advised to seek shelter in strong buildings, evacuate low-lying areas and to stay away from the coasts and river banks.
* Watch out for the passage of the "eye" of the typhoon indicated by a sudden occurrence of fair weather immediately after very bad weather with very strong winds coming gnerally from the north.
* When the "eye" of the typhoon hit the community do not venture away from the safe shelter because after one to two hours the worst weather will resume with the very strong winds coming from the south.
* Classes in all levels should be suspended and children should stay in the safety of strong buildings.
* Disaster preparedness and response agencies/organizations are in action with appropriate response to actual emergency.
PSWS # 4
METEOROLOGICAL CONDITIONS:
* A very intense typhoon will affect the locality.
* Very strong winds of more than 185 kph may be expected in at least 12 hours.
IMPACT OF THE WINDS:
* Coconut plantation may suffer extensive damage.
* Many large trees may be uprooted.
* Rice and corn plantation may suffer severe losses.
* Most residential and institutional buildings of mixed construction may be severely damaged.
* Electrical power distribution and communication services may be severely disrupted.
* In the overall, damage to affected communities can be very heavy.
PRECAUTIONARY MEASURES:
* The situation is potentially very destructive to the community.
* All travels and outdoor activities should be cancelled.
* Evacuation to safer shelters should have been completed since it may be too late under this situation.
* With PSWS #4, the locality is very likely to be hit directly by the eye of the typhoon. As the eye of the typhoon approaches, the weather will continuously worsen with the winds increasing to its strongest coming generally from the north. Then a sudden improvement of the weather with light winds (a lull) will be experienced. This means that the eye of the typhoon is over the locality. This improved weather may last for one to two hours depending on the diameter of the eye and the speed of movement. As the eye moves out of the locality, the worst weather experienced before the lull will suddenly commence. This time the very strong winds will come generally from the south.
* The disaster coordinating councils concerned and other disaster response organizations are now fully responding to emergencies and in full readiness to immediately respond to possible calamity.
FOOTNOTES: Important to note that when any Public Storm Warning Signal Number is hoisted or put in effect for the first time, the corresponding meteorological conditions are not yet prevailing over the locality. This is because the purpose of the signal is to warn the impending occurrence of the given meteorological conditions. It must be noted also that the approximate lead time to expect the range of the wind speeds given for each signal number is valid only when the signal number is put in effect for the first time. Thus, the associated meteorological conditions are still expected in at least 36 hours when PSWS #1 is put in effect initially; in at least 24 hours with PSWS #2; in at least 18 hours with PSWS #3; and in at least 12 hours with PSWS #4. The lead time shortens correspondingly in the subsequent issues of the warning bulletin when the signal number remains in effect as the tropical cyclone comes closer.
It is also important to remember that tropical cyclones are constantly in motion; generally towards the Philippines when PAGASA is issuing the warning. Therefore, the Public Storm Warning Signal Number over a threatened/ affected locality may be sequentially upgraded or downgraded. This means that PSWS #1 may be be upgraded to PSWS #2, then to PSWS #3 and to PSWS #4 as necessary when a very intense typhoon is approaching or downgraded when the typhoon is moving away. However, in case of rapid improvement of the weather condition due to the considerable weakening or acceleration of speed of movement of the tropical cyclone moving away from the country, the downgrading of signal may jump one signal level. For example, PSWS #3 may be downgraded to PSWS #1 or all signals from PSWS #2 may be lowered.
The delineation of areas for a given signal number is based on the intensity, size of circulation and the forecast direction and speed of movement of the tropical storm or typhoon at the time of issue of the warning bulletin. The change in intensity, size of circulation or movement of the tropical cyclone also determines the change in the PSWS number over a given locality.
http://kidlat.pagasa.dost.gov.ph/genmet/psws.html
PSWS # 1
METEOROLOGICAL CONDITIONS:
* A tropical cyclone will affect the locality.
* Winds of 30-60 kph may be expected in at least 36 hours or intermittent rains may be expected within 36 hours. (When the tropical cyclone develops very close to the locality a shorter lead time of the occurrence of the winds will be specified in the warning bulletin.)
IMPACT OF THE WINDS:
* Twigs and branches of small trees may be broken.
* Some banana plants may be tilted or downed.
* Some houses of very light materials (nipa and cogon) may be partially unroofed.
* Unless this warning signal is upgraded during the entire existence of the tropical cyclone, only very light or no damage at all may be sustained by the exposed communities.
* Rice crop, however, may suffer significant damage when it is in its flowering stage.
PRECAUTIONARY MEASURES:
* When the tropical cyclone is strong or is intensifying and is moving closer, this signal may be upgraded to the next higher level.
* The waves on coastal waters may gradually develop and become bigger and higher.
* The people are advised to listen to the latest severe weather bulletin issued by PAGASA every six hours. In the meantime, business may be carried out as usual except when flood occur.
* Disaster preparedness is activated to alert status.
PSWS # 2
METEOROLOGICAL CONDITIONS:
* A tropical cyclone will affect the the locality.
* Winds of greater than 60 kph and up to 100 kph may be expected in at least 24 hours.
IMPACT OF THE WINDS:
* Some coconut trees may be tilted with few others broken.
* Few big trees may be uprooted.
* Many banana plants may be downed.
* Rice and corn may be adversely affected.
* Large number of nipa and cogon houses may be partially or totally unroofed.
* Some old galvanized iron roofings may be peeled off.
* In general, the winds may bring light to moderate damage to the exposed communities.
PRECAUTIONARY MEASURES:
* The sea and coastal waters are dangerous to small sea crafts
* Special attention should be given to the latest position, the direction and speed of movement and the intensity of the storm as it may intensify and move towards the locality.
* The general public especially people traveling by sea and air are cautioned to avoid unnecessary risks.
* Outdoor activities of children should be postponed.
* Secure properties before the signal is upgraded.
* Disaster preparedness agencies / organizations are in action to alert their communities.
PSWS # 3
METEOROLOGICAL CONDITIONS:
* A tropical cyclone will affect the locality.
* Winds of greater than 100 kph up to 185 kph may be expected in at least 18 hours.
IMPACT OF THE WINDS:
* Many coconut trees may be broken or destroyed.
* Almost all banana plants may be downed and a large number of trees may be uprooted.
* Rice and corn crops may suffer heavy losses.
* Majority of all nipa and cogon houses may be unroofed or destroyed and there may be considerable damage to structures of light to medium construction.
* There may be widespread disruption of electrical power and communication services.
* In general, moderate to heavy damage may be experienced, particularly in the agricultural and industrial sectors.
PRECAUTIONARY MEASURES:
* The disturbance is dangerous to the communities threatened/affected.
* The sea and coastal waters will be very dangerous to all seacrafts.
* Travel is very risky especially by sea and air.
* People are advised to seek shelter in strong buildings, evacuate low-lying areas and to stay away from the coasts and river banks.
* Watch out for the passage of the "eye" of the typhoon indicated by a sudden occurrence of fair weather immediately after very bad weather with very strong winds coming gnerally from the north.
* When the "eye" of the typhoon hit the community do not venture away from the safe shelter because after one to two hours the worst weather will resume with the very strong winds coming from the south.
* Classes in all levels should be suspended and children should stay in the safety of strong buildings.
* Disaster preparedness and response agencies/organizations are in action with appropriate response to actual emergency.
PSWS # 4
METEOROLOGICAL CONDITIONS:
* A very intense typhoon will affect the locality.
* Very strong winds of more than 185 kph may be expected in at least 12 hours.
IMPACT OF THE WINDS:
* Coconut plantation may suffer extensive damage.
* Many large trees may be uprooted.
* Rice and corn plantation may suffer severe losses.
* Most residential and institutional buildings of mixed construction may be severely damaged.
* Electrical power distribution and communication services may be severely disrupted.
* In the overall, damage to affected communities can be very heavy.
PRECAUTIONARY MEASURES:
* The situation is potentially very destructive to the community.
* All travels and outdoor activities should be cancelled.
* Evacuation to safer shelters should have been completed since it may be too late under this situation.
* With PSWS #4, the locality is very likely to be hit directly by the eye of the typhoon. As the eye of the typhoon approaches, the weather will continuously worsen with the winds increasing to its strongest coming generally from the north. Then a sudden improvement of the weather with light winds (a lull) will be experienced. This means that the eye of the typhoon is over the locality. This improved weather may last for one to two hours depending on the diameter of the eye and the speed of movement. As the eye moves out of the locality, the worst weather experienced before the lull will suddenly commence. This time the very strong winds will come generally from the south.
* The disaster coordinating councils concerned and other disaster response organizations are now fully responding to emergencies and in full readiness to immediately respond to possible calamity.
FOOTNOTES: Important to note that when any Public Storm Warning Signal Number is hoisted or put in effect for the first time, the corresponding meteorological conditions are not yet prevailing over the locality. This is because the purpose of the signal is to warn the impending occurrence of the given meteorological conditions. It must be noted also that the approximate lead time to expect the range of the wind speeds given for each signal number is valid only when the signal number is put in effect for the first time. Thus, the associated meteorological conditions are still expected in at least 36 hours when PSWS #1 is put in effect initially; in at least 24 hours with PSWS #2; in at least 18 hours with PSWS #3; and in at least 12 hours with PSWS #4. The lead time shortens correspondingly in the subsequent issues of the warning bulletin when the signal number remains in effect as the tropical cyclone comes closer.
It is also important to remember that tropical cyclones are constantly in motion; generally towards the Philippines when PAGASA is issuing the warning. Therefore, the Public Storm Warning Signal Number over a threatened/ affected locality may be sequentially upgraded or downgraded. This means that PSWS #1 may be be upgraded to PSWS #2, then to PSWS #3 and to PSWS #4 as necessary when a very intense typhoon is approaching or downgraded when the typhoon is moving away. However, in case of rapid improvement of the weather condition due to the considerable weakening or acceleration of speed of movement of the tropical cyclone moving away from the country, the downgrading of signal may jump one signal level. For example, PSWS #3 may be downgraded to PSWS #1 or all signals from PSWS #2 may be lowered.
The delineation of areas for a given signal number is based on the intensity, size of circulation and the forecast direction and speed of movement of the tropical storm or typhoon at the time of issue of the warning bulletin. The change in intensity, size of circulation or movement of the tropical cyclone also determines the change in the PSWS number over a given locality.
http://kidlat.pagasa.dost.gov.ph/genmet/psws.html
Earthquake Drills Do's And Don'ts
SF Gate
DURING THE QUAKE
Indoors
* Stay inside
* DROP, COVER, AND HOLD ON! Move only a few steps to a nearby safe place. Take cover under and hold onto a piece of heavy furniture or stand against an inside wall. Stay indoors until the shaking stops and you're sure it's safe to exit. Stay away from windows and doors.
* **Never take an elevator
* If you are in bed, hold on, stay there, protect your head with a pillow.
Outdoors
* Find a clear spot away from buildings, trees, and power lines.
* Drop to the ground until the shaking stops.
In A Car
* Slow down and drive to a clear place (as described above).
* Turn on emergency flashers on and slow to a stop. Do not stop on overpasses, underpasses, or bridges. Be careful of overhead hazards such as power lines or falling building debris.
* Turn off the ignition and set the parking brake.
* Stay inside the car until the shaking stops.
PETS: During and after
* Don't try to hold your pet during a quake. Animals instinctively want to hide when their safety is threatened. If you get in their way, even the nicest pets may hurt you.
* Watch animals closely. Leash dogs and place them in a fenced yard.
* Pets may not be allowed into shelters for health and space reasons. Prepare an emergency pen for pets in the home that includes a 3-day supply of dry food and a large container of water.
* If you can't find your pet or must leave it at home after a quake, leave fresh water in nonspill containers such as bathtubs and sinks. Leave plenty of low-fat dry food, which deteriorates more slowly and is less tasty so pets won't try to eat it all at once. Leave a note indicating that you have a pet, where you will be and the date.
AFTER THE QUAKE
Personal Safety
* Expect aftershocks. Each time you feel one, DROP, COVER, AND HOLD ON!
* Check yourself for injuries. Protect yourself by wearing long pants, a long-sleeved shirt, sturdy shoes and work gloves.
* Listen to a battery-operated radio or television for the latest emergency information.
* Check others for injuries. Give first aid where appropriate. Do not move seriously injured persons unless they are in immediate danger of further injury.
* Remember to help your neighbors who may require special assistance--infants, the elderly, and people with disabilities.
Home
* Inspect your home for damage. Get everyone out if your home is unsafe.
* Telephone: Use the telephone only for emergencies. Check to make sure the receiver has not been shaken off the hook and is tying up the line.
* Fires: Look for and extinguish small fires.
* Gas: Check for gas leaks. If you smell gas or hear blowing or hissing noise, open a window and leave building. Turn off the gas at the outside main valve if you can and call the gas company.
* **Remember, only a professional can turn the gas back on.
* Electricity: Look for electrical system damage. Turn off the electricity at the main fuse box or circuit breaker if you see sparks or broken or frayed wires, or if smell hot insulation. If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice.
* Sewage, Water: Check for sewage and water lines damage. If you suspect sewage lines are damaged, avoid using the toilets and contact a plumber. If water pipes are damaged, contact the water company and avoid using water from the tap.
SOURCE: American Red Cross, FEMA, SF Fire Department, SF Chronicle
Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/earthquakes/archive/quakedrill.dtl#ixzz1Gsa2lxH2
SF Gate
DURING THE QUAKE
Indoors
* Stay inside
* DROP, COVER, AND HOLD ON! Move only a few steps to a nearby safe place. Take cover under and hold onto a piece of heavy furniture or stand against an inside wall. Stay indoors until the shaking stops and you're sure it's safe to exit. Stay away from windows and doors.
* **Never take an elevator
* If you are in bed, hold on, stay there, protect your head with a pillow.
Outdoors
* Find a clear spot away from buildings, trees, and power lines.
* Drop to the ground until the shaking stops.
In A Car
* Slow down and drive to a clear place (as described above).
* Turn on emergency flashers on and slow to a stop. Do not stop on overpasses, underpasses, or bridges. Be careful of overhead hazards such as power lines or falling building debris.
* Turn off the ignition and set the parking brake.
* Stay inside the car until the shaking stops.
PETS: During and after
* Don't try to hold your pet during a quake. Animals instinctively want to hide when their safety is threatened. If you get in their way, even the nicest pets may hurt you.
* Watch animals closely. Leash dogs and place them in a fenced yard.
* Pets may not be allowed into shelters for health and space reasons. Prepare an emergency pen for pets in the home that includes a 3-day supply of dry food and a large container of water.
* If you can't find your pet or must leave it at home after a quake, leave fresh water in nonspill containers such as bathtubs and sinks. Leave plenty of low-fat dry food, which deteriorates more slowly and is less tasty so pets won't try to eat it all at once. Leave a note indicating that you have a pet, where you will be and the date.
AFTER THE QUAKE
Personal Safety
* Expect aftershocks. Each time you feel one, DROP, COVER, AND HOLD ON!
* Check yourself for injuries. Protect yourself by wearing long pants, a long-sleeved shirt, sturdy shoes and work gloves.
* Listen to a battery-operated radio or television for the latest emergency information.
* Check others for injuries. Give first aid where appropriate. Do not move seriously injured persons unless they are in immediate danger of further injury.
* Remember to help your neighbors who may require special assistance--infants, the elderly, and people with disabilities.
Home
* Inspect your home for damage. Get everyone out if your home is unsafe.
* Telephone: Use the telephone only for emergencies. Check to make sure the receiver has not been shaken off the hook and is tying up the line.
* Fires: Look for and extinguish small fires.
* Gas: Check for gas leaks. If you smell gas or hear blowing or hissing noise, open a window and leave building. Turn off the gas at the outside main valve if you can and call the gas company.
* **Remember, only a professional can turn the gas back on.
* Electricity: Look for electrical system damage. Turn off the electricity at the main fuse box or circuit breaker if you see sparks or broken or frayed wires, or if smell hot insulation. If you have to step in water to get to the fuse box or circuit breaker, call an electrician first for advice.
* Sewage, Water: Check for sewage and water lines damage. If you suspect sewage lines are damaged, avoid using the toilets and contact a plumber. If water pipes are damaged, contact the water company and avoid using water from the tap.
SOURCE: American Red Cross, FEMA, SF Fire Department, SF Chronicle
Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=/earthquakes/archive/quakedrill.dtl#ixzz1Gsa2lxH2
Monday, March 14, 2011
Scientists Say Earthquake Caused Shift in Earth's Axis
Vanessa Evans – Sun Mar 13, 5:44 pm ET
It appears the 8.9 earthquake that shook Japan on Friday as well as causing massive damage and loss of life in that nation, also had some global implications as well. Multiple scientific reports started surfacing in the aftermath of the quake that estimate that the actual rotation of the Earth may have been affected, as well as Japan's physical position and other global phenomena.
The scientific community takes an intense interest in natural disasters like the Japanese earthquake because monitoring the action both during and after the event can provide huge clues as to how the Earth itself is constructed and moves.
There have been several developments in scientific understanding of the Japanese earthquake in the last couple of days.
* Although the largest earthquake recorded on Friday was the massive 8.9 quake that caused the vast majority of the damage, there have been hundreds of aftershocks, some of which reached magnitude 6 strength, according to the U.S. Geological Survey.
* Any number of those aftershocks were as large as the earthquake that shook Christchurch, New Zealand, late last month.
* Geophysicist Richard Gross of NASA's Jet Propulsion Laboratory in California, has estimated that the Japanese earthquake shortened the Earth's day by 1.8 microseconds. Gross also said that the axis of the Earth probably shifted about 6.5 inches, which affects how it rotates, but not its position or movement in space.
* The Japanese Meteorological Agency has actually upgraded the earthquake to a magnitude of 9.0, although other global agencies have yet to follow suit. The U.S. Geological Survey's Susan Hough maintained that great quakes are harder to measure and that a difference of .1 magnitude in initial strength estimates is not unusual.
* The U.S. Geological Survey initially estimated that Japan as a whole has physically moved by approximately 8 feet, but other scientists around the globe have estimated that some parts of the country may actually have moved as much as 12 feet closer to North America. In addition, parts of the country's terrain are not permanently under sea level, which will make it difficult for the flooding caused by the tsunami to drain.
* The tsunami that followed the earthquake was caused when the Pacific Plate shifted, actually moving under Japan at the Japan Trench. This caused additional tremors and the devastating wave that crashed into the nation's east coast.
* The loss of 1.8 microseconds as a result of the shift in the Earth's axis is unlikely to cause more than minute changes, but among those changes will actually be differences in the passing of the seasons. This will only be observable using satellite navigation systems with very precise monitoring equipment.
* The shift of the Earth's axis and loss of time is similar to that experienced after the Chilean earthquake last year, which sped up the Earth's rotation and resulted in the loss of 1.26 microseconds.
Reference: http://news.yahoo.com/
Vanessa Evans – Sun Mar 13, 5:44 pm ET
It appears the 8.9 earthquake that shook Japan on Friday as well as causing massive damage and loss of life in that nation, also had some global implications as well. Multiple scientific reports started surfacing in the aftermath of the quake that estimate that the actual rotation of the Earth may have been affected, as well as Japan's physical position and other global phenomena.
The scientific community takes an intense interest in natural disasters like the Japanese earthquake because monitoring the action both during and after the event can provide huge clues as to how the Earth itself is constructed and moves.
There have been several developments in scientific understanding of the Japanese earthquake in the last couple of days.
* Although the largest earthquake recorded on Friday was the massive 8.9 quake that caused the vast majority of the damage, there have been hundreds of aftershocks, some of which reached magnitude 6 strength, according to the U.S. Geological Survey.
* Any number of those aftershocks were as large as the earthquake that shook Christchurch, New Zealand, late last month.
* Geophysicist Richard Gross of NASA's Jet Propulsion Laboratory in California, has estimated that the Japanese earthquake shortened the Earth's day by 1.8 microseconds. Gross also said that the axis of the Earth probably shifted about 6.5 inches, which affects how it rotates, but not its position or movement in space.
* The Japanese Meteorological Agency has actually upgraded the earthquake to a magnitude of 9.0, although other global agencies have yet to follow suit. The U.S. Geological Survey's Susan Hough maintained that great quakes are harder to measure and that a difference of .1 magnitude in initial strength estimates is not unusual.
* The U.S. Geological Survey initially estimated that Japan as a whole has physically moved by approximately 8 feet, but other scientists around the globe have estimated that some parts of the country may actually have moved as much as 12 feet closer to North America. In addition, parts of the country's terrain are not permanently under sea level, which will make it difficult for the flooding caused by the tsunami to drain.
* The tsunami that followed the earthquake was caused when the Pacific Plate shifted, actually moving under Japan at the Japan Trench. This caused additional tremors and the devastating wave that crashed into the nation's east coast.
* The loss of 1.8 microseconds as a result of the shift in the Earth's axis is unlikely to cause more than minute changes, but among those changes will actually be differences in the passing of the seasons. This will only be observable using satellite navigation systems with very precise monitoring equipment.
* The shift of the Earth's axis and loss of time is similar to that experienced after the Chilean earthquake last year, which sped up the Earth's rotation and resulted in the loss of 1.26 microseconds.
Reference: http://news.yahoo.com/
Phillipine Fault Zone
Philippine Fault Zone one of world’s longest at 1,200 km
By Alcuin Papa, Philippine Daily Inquirer
By Alcuin Papa, Philippine Daily Inquirer
APART from the profusion of spectacular landscapes and seascapes that has made it the favorite of many travelers, it would seem that the paradise island of Palawan also offers the safest haven for those fearful of a Haiti-like tremor occurring in the country.
Compared to other parts of the Philippines, Palawan is “relatively stable” geologically, according to Mahar Lagmay, a professor of the University of the Philippines National Institute of Geological Sciences (UP-NIGS).
“There are hardly any earthquakes in Palawan and certainly none strong enough to cause major damage. The whole island is probably the most stable area of land in the country,” Lagmay said.
An expert on earthquake faults, Lagmay has constructed a map of earthquake epicenters which he plotted using information from the United States Geological Survey (USGS) from 1929 to 2009.
Lagmay said there were hardly any active faults under the island compared to the rest of the country. (A fault or fault line is a fracture in the rock within the earth’s crust that is the causal location of most earthquakes.)
Continental, not oceanic, rock
While Palawan does have fault lines, these are “old” and experts are still debating whether these fault lines are active or not, Lagmay said.
For instance, there is an ongoing and heated debate on whether the Ulugan Bay fault near the famed Palawan Underground River is active, Lagmay said.
Lagmay believes Palawan is stable largely because the island was once part of continental Asia which separated around 100 million years ago and drifted toward the Philippines.
“The rock of the island is continental and different from other parts of the country, which is made of oceanic rock,” he said.
Hence, the crust of the island is thicker at 30 kilometers, compared to the oceanic rock’s 12 km, having derived from the Pacific seabed.
“The crust of the island is thicker and older and, therefore, not as prone to earthquakes,” said Lagmay.
Compared to other parts of the Philippines, Palawan is “relatively stable” geologically, according to Mahar Lagmay, a professor of the University of the Philippines National Institute of Geological Sciences (UP-NIGS).
“There are hardly any earthquakes in Palawan and certainly none strong enough to cause major damage. The whole island is probably the most stable area of land in the country,” Lagmay said.
An expert on earthquake faults, Lagmay has constructed a map of earthquake epicenters which he plotted using information from the United States Geological Survey (USGS) from 1929 to 2009.
Lagmay said there were hardly any active faults under the island compared to the rest of the country. (A fault or fault line is a fracture in the rock within the earth’s crust that is the causal location of most earthquakes.)
Continental, not oceanic, rock
While Palawan does have fault lines, these are “old” and experts are still debating whether these fault lines are active or not, Lagmay said.
For instance, there is an ongoing and heated debate on whether the Ulugan Bay fault near the famed Palawan Underground River is active, Lagmay said.
Lagmay believes Palawan is stable largely because the island was once part of continental Asia which separated around 100 million years ago and drifted toward the Philippines.
“The rock of the island is continental and different from other parts of the country, which is made of oceanic rock,” he said.
Hence, the crust of the island is thicker at 30 kilometers, compared to the oceanic rock’s 12 km, having derived from the Pacific seabed.
“The crust of the island is thicker and older and, therefore, not as prone to earthquakes,” said Lagmay.
No major faults
The island is also not bordered by any major trench or fault line, he said.
“The South China Sea area is more stable tectonically. Combined with the continental material, there is little chance for the development of active faults in Palawan,” he said.
Also, the movement of the ground in the South China Sea is not as fast as the eastern side of Luzon, which is moving toward the Asian mainland at the rate of 7 centimeters a year, and the eastern side of Mindanao, which is moving toward the Asian mainland at 10 cm a year.
“Because of the slow movement, there is no compression of forces in the island,” Lagmay said.
On the other hand, large parts of the Philippine archipelago are sandwiched between two trenches, the Manila Trench in the west and the Philippine Trench in the east.
“Movements in these trenches generate stress in the faults. That is why there are so many earthquakes in the mainland [Philippines],” he said.
“If you ask me where I would build a house in the country, I’d say Palawan,” he said.
Longest fault system
According to Lagmay, the Philippines is encased in an intricate network of trenches and faults that is one of the most, if not the most complex in the world in terms of tectonics and geology.
The centerpiece of the country’s fault system is the Philippine Fault Zone (PFZ) which is one of the longest in the world at around 1,200 km.
The PFZ starts in Aparri and snakes past the Cordilleras, passing through Nueva Ecija, down to Quezon and the Bondoc Peninsula into Leyte, and from there skipping into northern Mindanao to the southern end of the island into Davao.
The PFZ, Lagmay explained, is a left-lateral strike slip fault. This means that if you were to put one foot on one side of the fault and the other foot on the other side of the fault, the left side of the fault would be moving toward you while the right side would be moving away from you. Also, the right side, or block, would be more advanced than the left block.
A strike-slip fault means the two blocks are moving against each other horizontally.
Lagmay explained that the length of the fault is related to its capacity to generate a large- magnitude earthquake.
“The larger the fault, the greater its potential to produce a strong earthquake,” he said.
In 1990, the PFZ generated a 7.9-magnitude quake that shook Metro Manila and Luzon.
Underwater trenches
Other earthquake fault lines are the trenches running underwater on the western and eastern sides of the country.
There is the Manila Trench on the west of the country which runs from the Batanes islands, curving through the waters off the Ilocos region, Pangasinan, Zambales and into Mindoro island.
According to the Philippine Institute of Volcanology and Seismology (Phivolcs), movement in the Manila Trench caused the Jan. 12 magnitude 5.2 earthquake near Olongapo City that was felt in Metro Manila.
There is also the longer Philippine Trench located underwater east of the country. It runs roughly from waters off Aurora down to Samar, and past Mindanao.
Other underwater trenches in the country include the East Luzon Trough, the Negros Trench that is connected to the Sulu Trench, and the Cotabato Trench.
Smaller faults
In addition, there are also the smaller faults. Notable of the smaller fault lines is the Valley Fault System, also known as the Western Marikina Valley Fault System, which is nearest to Metro Manila.
According to Lagmay, Metro Manila was damaged heavily six times in the last 400 years by earthquakes. But the source of these earthquakes is uncertain.
A study by the USGS and the Phivolcs in 2000 showed that the Valley Fault experienced four large surface rupture events since 600 AD, occurring over a period separated by between 200 and 400 years. The study also said the last fault event in the Valley Fault occurred in the past 200 years.
Lagmay said the Valley Fault is capable of generating an earthquake with a magnitude of between 6 and 7.
Luzon, Mindanao faults
Besides the Valley Fault system, other faults in Luzon include the West Ilocos Fault System, the Dummon River Fault System in Cagayan, the East Zambales Fault, the Iba Fault and the Lubang Fault.
Fault systems in the Visayas include the West Panay Fault, the Southern Samar Lineament, the Central Negros Fault, the Cebu Lineament and the East Bohol Fault.
In Mindanao, there is the Mindanao Fault, the Lanao Fault System, the Davao River Fault, the Central Mindanao Fault and the Tangbulan Fault.
The result of all these faults is that between 5,000 and 7,000 earthquakes occur in the country each year, or an average of between 200 and 250 quakes a day, according to Phivolcs. But most of these earthquakes are not felt. Last year, Phivolcs tallied around 210 earthquakes in the country.
“As we are talking right now, there is a small earthquake occurring somewhere in the country,” Lagmay said.
The island is also not bordered by any major trench or fault line, he said.
“The South China Sea area is more stable tectonically. Combined with the continental material, there is little chance for the development of active faults in Palawan,” he said.
Also, the movement of the ground in the South China Sea is not as fast as the eastern side of Luzon, which is moving toward the Asian mainland at the rate of 7 centimeters a year, and the eastern side of Mindanao, which is moving toward the Asian mainland at 10 cm a year.
“Because of the slow movement, there is no compression of forces in the island,” Lagmay said.
On the other hand, large parts of the Philippine archipelago are sandwiched between two trenches, the Manila Trench in the west and the Philippine Trench in the east.
“Movements in these trenches generate stress in the faults. That is why there are so many earthquakes in the mainland [Philippines],” he said.
“If you ask me where I would build a house in the country, I’d say Palawan,” he said.
Longest fault system
According to Lagmay, the Philippines is encased in an intricate network of trenches and faults that is one of the most, if not the most complex in the world in terms of tectonics and geology.
The centerpiece of the country’s fault system is the Philippine Fault Zone (PFZ) which is one of the longest in the world at around 1,200 km.
The PFZ starts in Aparri and snakes past the Cordilleras, passing through Nueva Ecija, down to Quezon and the Bondoc Peninsula into Leyte, and from there skipping into northern Mindanao to the southern end of the island into Davao.
The PFZ, Lagmay explained, is a left-lateral strike slip fault. This means that if you were to put one foot on one side of the fault and the other foot on the other side of the fault, the left side of the fault would be moving toward you while the right side would be moving away from you. Also, the right side, or block, would be more advanced than the left block.
A strike-slip fault means the two blocks are moving against each other horizontally.
Lagmay explained that the length of the fault is related to its capacity to generate a large- magnitude earthquake.
“The larger the fault, the greater its potential to produce a strong earthquake,” he said.
In 1990, the PFZ generated a 7.9-magnitude quake that shook Metro Manila and Luzon.
Underwater trenches
Other earthquake fault lines are the trenches running underwater on the western and eastern sides of the country.
There is the Manila Trench on the west of the country which runs from the Batanes islands, curving through the waters off the Ilocos region, Pangasinan, Zambales and into Mindoro island.
According to the Philippine Institute of Volcanology and Seismology (Phivolcs), movement in the Manila Trench caused the Jan. 12 magnitude 5.2 earthquake near Olongapo City that was felt in Metro Manila.
There is also the longer Philippine Trench located underwater east of the country. It runs roughly from waters off Aurora down to Samar, and past Mindanao.
Other underwater trenches in the country include the East Luzon Trough, the Negros Trench that is connected to the Sulu Trench, and the Cotabato Trench.
Smaller faults
In addition, there are also the smaller faults. Notable of the smaller fault lines is the Valley Fault System, also known as the Western Marikina Valley Fault System, which is nearest to Metro Manila.
According to Lagmay, Metro Manila was damaged heavily six times in the last 400 years by earthquakes. But the source of these earthquakes is uncertain.
A study by the USGS and the Phivolcs in 2000 showed that the Valley Fault experienced four large surface rupture events since 600 AD, occurring over a period separated by between 200 and 400 years. The study also said the last fault event in the Valley Fault occurred in the past 200 years.
Lagmay said the Valley Fault is capable of generating an earthquake with a magnitude of between 6 and 7.
Luzon, Mindanao faults
Besides the Valley Fault system, other faults in Luzon include the West Ilocos Fault System, the Dummon River Fault System in Cagayan, the East Zambales Fault, the Iba Fault and the Lubang Fault.
Fault systems in the Visayas include the West Panay Fault, the Southern Samar Lineament, the Central Negros Fault, the Cebu Lineament and the East Bohol Fault.
In Mindanao, there is the Mindanao Fault, the Lanao Fault System, the Davao River Fault, the Central Mindanao Fault and the Tangbulan Fault.
The result of all these faults is that between 5,000 and 7,000 earthquakes occur in the country each year, or an average of between 200 and 250 quakes a day, according to Phivolcs. But most of these earthquakes are not felt. Last year, Phivolcs tallied around 210 earthquakes in the country.
“As we are talking right now, there is a small earthquake occurring somewhere in the country,” Lagmay said.
Subscribe to:
Posts (Atom)