Earthquakes

In the area you have selected (Philippines) earthquake hazard is classified as high according to the information that is currently available. This means that there is more than a 20% chance of potentially-damaging earthquake shaking in your project area in the next 50 years. Based on this information, the impact of earthquake must be considered in all phases of the project, in particular during design and construction. Project planning decisions, project design, and construction methods should take into account the level of earthquake hazard. Further detailed information should be obtained to adequately account for the level of hazard.

The Philippines is considered to be one of the most earthquakes-prone countries of the world. There are a number of earthquake generators in the country. The archipelago is bounded by oppositely-dipping subduction zones. As well as transected by a number of fault, where movement are periodically detected through the recordings of tectonic earthquakes.

At least five imperceptible to perceptible earthquakes occurs per day. However, there are some regions of the country, which are considered more earthquake prone than others, such as east tern Mindanao, Leyte and Samara which host an average of 16 felt earthquakes per year. The most recent destructive earthquakes were the 16 august 1976 Moro gulf earthquakes (Ms=7.9), which triggered a tsunami, the 16 July 1990 Luzon earthquakes (Ms=7.8) , which was generated by movement along the northern segment of the Philippine fault zone and the 15 November 1994 Mindoro earthquakes (ms=7.1) which like wise triggered a tsunami.

Seismological observation in the Philippines could be traced as early as 1884. but it was only after 1986 that the Philippine institute of volcano logy and seismology Come in to being , which took on the responsibility of seismic monitoring in the country.

Earthquakes are impossible to predict but based on historical records, Metro Manila's West Valley Fault is due for the Next Big One within our lifetimes.

A possible magnitude-7.2 earthquake looms around the corner if the West Valley Fault along the eastern side of Metro Manila cracks, Renato Solidum Jr., Philippine Institute of Volcanology and Seismology (Phivolcs) director warns.

The West Valley Fault runs from the heights of Sierra Madre down to Laguna. It crosses the eastern side of Quezon City, western side of Marikina, western part of Pasig, eastern part of Makati, parts of Taguig, and Muntinlupa.

The fault has moved four times in the past 1,400 years. On average, it moves every 400 years, “+/- 10 to 100 years, maybe,” The last time an earthquake occurred along the West Valley fault was in 1658, around 355 years ago.

The earthquake can occur anywhere along the West Valley Fault, including Metro Manila. But a 7.2 magnitude earthquake can shake the ground even a hundred kilometers away, which means that it can shake the whole of Metro Manila and its surrounding provinces.

Solidum reiterates that weak, poorly-designed, and poorly-constructed buildings far from the earthquake fault are still vulnerable to destruction.

Grounds can also be affected by liquefaction, a process where loose, sandy sediments behave like liquid, Solidum explains. It becomes weak. This can cause poorly designed or constructed buildings and homes to subside or tilt, roads fissured, and water banks broken.

Areas near the waters like Marikina Valley down to Manila de Ba-i, and the coastal cities of Metro Manila are also more likely to experience stronger ground shaking due to the softer ground they sit on.

What to do in an earthquake

Your past experience in earthquakes may give you a false sense of safety; you didn't do anything, or you ran outside, yet you survived with no injuries. Or perhaps you got under your desk and others thought you overreacted. However, you likely have never experienced the kind of strong earthquake shaking that is possible in much larger earthquakes: sudden and intense back and forth motions of several feet per second will cause the floor or the ground to jerk sideways out from under you, and every unsecured object around you could topple, fall, or become airborne, potentially causing serious injury. This is why you must learn to immediately protect yourself after the first jolt... don't wait to see if the earthquake shaking will be strong!

In MOST situations, you will reduce your chance of injury if you:

DROP where you are, onto your hands and knees. This position protects you from being knocked down and also allows you to stay low and crawl to shelter if nearby.

COVER your head and neck with one arm and hand

If a sturdy table or desk is nearby, crawl underneath it for shelter
If no shelter is nearby, crawl next to an interior wall (away from windows)
Stay on your knees; bend over to protect vital organs

HOLD ON until shaking stops

Under shelter: hold on to it with one hand; be ready to move with your shelter if it shifts
No shelter: hold on to your head and neck with both arms and hands.

Why Drop, Cover, and Hold On? Our special report explains why official rescue teams, emergency preparedness experts, and others recommend "Drop, Cover, and Hold On" as the best way, in most situations, to protect yourself during earthquake shaking.

WHY RESCUERS AND EXPERTS RECOMMEND DROP, COVER, AND HOLD ON

Trying to move during shaking puts you at risk: Earthquakes occur without any warning and may be so violent that you cannot run or crawl; you therefore will most likely be knocked to the ground where you happen to be. So it is best to drop before the earthquake drops you, and find nearby shelter or use your arms and hands to protect your head and neck. "Drop, Cover, and Hold On" gives you the best overall chance of quickly protecting yourself during an earthquake... even during quakes that cause furniture to move about rooms, and even in buildings that might ultimately collapse.

The greatest danger is from falling and flying objects: Studies of injuries and deaths caused by earthquakes over the last several decades show that you are much more likely to be injured by falling or flying objects (TVs, lamps, glass, bookcases, etc.) than to die in a collapsed building. "Drop, Cover, and Hold On" (as described above) will protect you from most of these injuries.

If there is no furniture nearby, you can still reduce the chance of injury from falling objects by getting down next to an interior wall and covering your head and neck with your arms (exterior walls are more likely to collapse and have windows that may break). If you are in bed, the best thing to do is to stay there and cover your head with a pillow. Studies of injuries in earthquakes show that people who moved from their beds would not have been injured if they had remained in bed.

You can also reduce your chance of injury or damage to your belongings by securing them in the first place. Secure top heavy furniture to walls with flexible straps. Use earthquake putty or velcro fasteners for objects on tables, shelves, or other furniture. Install safety latches on cabinets to keep them closed.

- If you’re in a HIGH-RISE BUILDING, and you are not near a desk or table, move against an interior wall, and protect your head with your arms. Do not use the elevators.

- If you’re OUTDOORS, move to a clear area, away from trees, signs, buildings, or downed electrical wires and poles.

- If you’re on a SIDEWALK NEAR BUILDINGS, duck into a doorway to protect yourself from falling bricks, glass, plaster, and other debris.

- If you’re DRIVING, pull over to the side of the road and stop. Avoid overpasses, power lines, and other hazards. Stay inside the vehicle until the shaking is over.

- If you’re in a CROWDED STORE, do not rush for exits. Move away from display shelves containing objects that could fall.

- If you’re in a WHEELCHAIR, stay in it. Move to cover, if possible, lock your wheels, and protect your head with your arms.

- If you’re in the KITCHEN, move away from the refrigerator, stove, and overhead cupboards.

- If you’re in a STADIUM or THEATER, stay in your seat and protect your head with your arms. Do not try to leave until the shaking is over. Then leave in a calm, orderly manner.

Be prepared for AFTERSHOCKS, and plan where you will take cover when they occur. Aftershocks can occur in the first hours, days, weeks, or even months after the quake. Be prepared to Drop, Cover, & Hold again.

Some links

Here are some videos from Youtube that show you how it looks like.

Credit to the owner of the video