Exploring structural controls on sumatran earthquakes

Abstract

A series of linked marine and land studies have recently targeted the Sumatra subduction zone, focusing on the 2004 and 2005 plate boundary earthquake ruptures in Indonesia. A collaborative research effort by scientists from the United Kingdom (UK Sumatra Consortium), Indonesia, United States, France, and Germany is focusing on imaging the crustal structure of the margin to examine controls on along-strike and updip earthquake rupture propagation. The fundamental science objective is to examine how margin architecture and properties control earthquake rupture location and propagation. The project collected extensive geophysical, geological, and seismological data across the offshore and onshore parts of the subduction zone of north central Sumatra (Figures 1 and 2). Offshore data collection within the project included the largest research vessel exchange program undertaken to date, involving an exchange of research vessel time between countries to maximize efficiency. The main surveys of the project spanned two segment boundaries of the subduction zone (Figure 1): between the 2004 and 2005 ruptures at Simeulue Island, and at the southern limit of the 2005 rupture, adjacent to a segment that ruptured in 1935, at the Nias and Batu islands. The extensive geological and geophysical data examine variations, at a range of scales, in seismicity, fore-arc deformation, plate boundary properties, lithospheric structure, and sedimentary properties and processes.