In March 2005 the Sunda megathrust earthquake, with a moment magnitude of 8.6, occurred. Concern was then focused further south on the Mentawai area, where large earthquakes had occurred in 1797 (magnitude 8.8) and 1833 (magnitude 9.0). On 12 September 2007, a magnitude 8.4 earthquake occurred, followed by a magnitude 7.9 earthquake 12 hours later. This paper shows that these earthquakes ruptured only a fraction of the area ruptured in 1833 and conclude that the stress state on the portion of the Sunda megathrust that ruptured in 1797 and 1833 was probably not adequate for the development of a single major large rupture in 2007, meaning that the potential for a large megathrust event in the Mentawai area thus remains high.
- A. Ozgun Konca
- Jean-Philippe Avouac
- Don V. Helmberger