Urgent measurement of coseismic displacement and tsunami height due to the 09/07 Mentawai Islands earthquake sequence

Abstract

The September 2007 Bengkulu earthquake sequence of on the Sunda Megathrust west of Sumatra continues the rupture of an entire plate boundary and it is now the case that from the Andaman Islands to Enganno Island, a distance of more than 2500km, less than 300km of the great Sunda megathrust remains un-ruptured in the last 5 years (see for Konca etal 2008 for example). The September 2007 earthquakes presented a first opportunity to test the predictions of earlier NERC funded work which suggests that the height of tsunamis in the near-field of megathrust earthquakes is predictable in the short term by measuring the vertical coseismic displacement on the coast. In November and December 2007 we travelled to Sumatra and used NERC GEF GPS equipment to make unprecedentedly detailed measurements of the run up of the tsunami from the 2007 earthquake. Here we report on this deployment.