Welcome to EarthquakePage

Four main Earthquake Types

P-waves and S-waves (which are body waves), and Rayleigh waves and Love waves (which are surface waves)

Body waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes radiate seismic energy as both body and surface waves.P waves are also known as compressional waves, because of the pushing and pulling they do. The second type of body wave is the S wave or secondary wave, which is the second wave you feel in an earthquake. An S wave is slower than a P wave and can only move through solid rock, not through any liquid medium.

Seismic Propagation & Types

The first kind of surface wave is called a Love wave, it's the fastest surface wave and moves the ground from side-to-side. The other kind of surface wave is the Rayleigh wave, it moves the ground up and down, and side-to-side in the same direction that the wave is moving.

A major 7.0 magnitude earthquake has struck Alaska

Officials have registered 40 aftershocks: 10 with magnitudes above 4.0 and three with magnitudes above 5.0, the Alaska Earthquake Center reported.

5.7 magnitude aftershock

Damage on Vine Road, south of Wasilla, Alaska, after earthquakes on Nov. 30, 2018. Back-to-back earthquakes measuring 7.0 and 5.7 shattered highways

7.0 magnitude quake

A stranded vehicle lies on a collapsed roadway near the airport after an earthquake in Anchorage, Alaska, U.S. November 30, 2018

Seismic energy release & ground displacement

Steady background motions of Earth’s crust occur as a result of tectonic plate motions. The earthquake relieves the stress, the fault is stuck again, and the cycle of stress buildup and release begins anew. If an earthquake generates enough shaking intensity , built structures can be severely damaged and cliffs and sloping ground can be temporarily or permanently destabilised.

Generation of Seismic Waves

An earthquake is the result of a sudden release of stored energy in the Earth's crust that creates seismic waves. Earthquakes are accordingly measured with a seismometer, commonly known as a seismograph. The magnitude of an earthquake is conventionally reported using the Richter scale or a related Moment scale (with magnitude 3 or lower earthquakes being hard to notice and magnitude 7 causing serious damage over large areas).

Earthquakes are caused by tectonic plates getting stuck and putting a strain on the ground. The strain becomes so great that rocks give way by breaking and sliding along fault planes. Earthquakes may occur naturally or as a result of human activities.

What to learn more about seismic activity?

Generation of Earthquakes

Earthquakes - National Disasters