Enormous earthquake in Indonesia causes tidal waves

26 December 2004

An enormous earthquake occurred off the West coast of Sumatra today at 11:59am ESST (0.58 UT) and measured magnitude 8.9 on the Richter scale.

The epicentre is located approximately 320 km west of Medan, Sumatra. This earthquake is the result of plate collision, caused by the Australian plate moving northwards about 7cm per year.

"Shallow earthquakes of this size are very destructive and can cause serious damage in a radius of 200-300km," said Dr Cvetan Sinadinovski, Duty Seismologist with Geoscience Australia.

"A destructive tsunami has been generated in the Indian Ocean. A half a metre wave passed Cocos Island and may affect the NW coast of Australia, but the wave height may vary dramatically depending on local effects.

"This is the largest earthquake in the world for forty years, and the fifth largest in the world since 1900," said Dr Sinadinovski.

Topic contact: media@ga.gov.au Last updated: October 4, 2013