Tsunami – Samoa 2009

Samoa is a group of 10 volcanic islands with a total land area of 2800 sq km, located about 2,900 kms north east of Auckland, New Zealand.  Four of the islands are inhabited by about 180,741 people (2006 Population Census) 78% of whom live on the island of Upolu, the second largest of all the islands.

At around 6:45am on Tuesday, 29 September 2009, the southern coast of the island of Upolu, Samoa was shaken by an earthquake measuring 8.2 on the Richter scale, which had occurred in the Tongan Trench just east of Samoa hit. This was followed by a fast moving tsunami.

The tsunami took only a few minutes and left hundreds of people reeling from the sheer shock of it all and its devastating aftermath. Some of the survivors spoke of a crescendo of successive waves up to fifteen metres high scouring the land clean of life, others talked of a moving sea wall smashing them against the escarpment. 

192 people including nine foreigners died that day in American Samoa, Samoa and Tonga (Niuatoputapu) – most died in Samoa. Close to 50% of them were children under the age of 10.

According to Nature magazine, 19 August 2010:

“On 29 September 2009, within two minutes of the initiation of a normal faulting event with moment magnitude 8.1 in the outer trench-slope at the northern end of the Tonga subduction zone, two major interplate underthrusting subevents (both with moment magnitude 7.8), with total moment equal to a second great earthquake of moment magnitude 8.0, ruptured the nearby subduction zone megathrust. The collective faulting produced tsunami waves with localized regions of about 12 metres run-up that claimed 192 lives in Samoa, American Samoa and Tonga. Overlap of the seismic signals obscured the fact that distinct faults separated by more than 50 km had ruptured with different geometries, with the triggered thrust faulting only being revealed by detailed seismic wave analyses.”

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