Educational Resources

What is an earthquake?

• An earthquake is the sudden release of strain energy in the Earth's crust resulting in waves of shaking that radiate outwards from the earthquake source. When stresses in the crust exceed the strength of the rock, it breaks along lines of weakness, either a pre-existing or new fault plane. The point where an earthquake starts is termed the focus or hypocentre and may be many kilometres deep within the earth. The point at the surface directly above the focus is called the earthquake epicentre. Source

Where do earthquakes occur?

• Anywhere!

Which countries have the largest and most frequent earthquakes?

• Around 75% of the world's seismic energy is released at the edge of the Pacific, where the thinner Pacific plate is forced beneath thicker continental crust along 'subduction zones'. This 40,000 km band of seismicity stretches up the west coasts of South and Central America and from the Northern USA to Alaska, the Aleutians, Japan, China, the Philippines, Indonesia and Australasia. Source

How are earthquakes recorded?

• Earthquakes are recorded by instruments called seismographs. The recording they make is called a seismogram. The seismograph has a base that sets firmly in the ground, and a heavy weight that hangs free. When an earthquake causes the ground to shake, the base of the seismograph shakes too, but the hanging weight does not. Instead the spring or string that it is hanging from absorbs all the movement. The difference in position between the shaking part of the seismograph and the motionless part is what is recorded. Source.

What is flooding?

• "Flooding is a temporary overflow of water onto land that is normally dry"(Link). Flooding can either develop slowly or become a flash flood where it comes without warning.

Is the Philippines heavily affected by flooding?

• Absolutely. The Philippines is situated in the tropics where heavy downpour is commonplace.

Can we prepare for flooding?

• Unlike earthquakes, the weather can be monitored days ahead of it landing on shore.