Undersea earthquakes

Click on the arrow on this animation to see how an undersea earthquake can cause tsunami.

The animation above shows how the lower tectonic plate (the Australian Plate) moves under the top plate (the Eurasian Plate) pulling the top plate down with it. This creates a build-up of pressure. This pressure causes the top plate to rebound to its original position, causing an undersea earthquake and potentially a tsunami.

The Indian Ocean Tsunami of 2004 was caused by an undersea earthquake measuring a magnitude of 9.3. This earthquake occurred off the west coast of Sumatra where the Indo-Australian plate is sliding under the Eurasian Plate. The part of the fault that ruptured and caused the tsunami was 1200km long.

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