Bathymetric survey images structure off Sumatra

Authors


Abstract

Fault rupture models and aftershock activities of both the 26 December 2004 Mw 9.3 and the 28 March 2005 Mw 8.7 earthquakes postulate a strong structural segmentation of the Sumatra fore arc, or the region between a subduction trench and the volcanic arc. The 2004 earthquake rupture propagated some 1200–1400 kilometers to the northwest from the epicenter along the plate boundary Yet the rupture ended abruptly at a southern boundary crosscutting the upper plate from the trench to the island of Simeulue. Similarly, the rupture plane and aftershock distribution of the 2005 earthquake are confined to a zone some 300–400 kilometers around the epicenter off Nias Island, clearly distinguishable from the northern rupture zone.

Ancillary