Frictional afterslip following the 2005 Nias-Simeulue earthquake, Sumatra

• Main Authors: Hsu, Ya-Ju, Simons, Mark, Avouac, Jean-Philippe, Galetzka, John, Sieh, Kerry, Chlieh, Mohamed, Natawidjaja, Danny H., Prawirodirdjo, Linette, Bock, Yehuda
• Format: Article
• Language: English
• Published: 2012
• Subjects: DRNTU::Science::Geology::Volcanoes and earthquakes
• Online Access: https://hdl.handle.net/10356/94599; http://hdl.handle.net/10220/8671
• Institution: Nanyang Technological University

Continuously recording Global Positioning System stations near the 28 March 2005 rupture of the Sunda megathrust [moment magnitude (Mw) 8.7] show that the earthquake triggered aseismic frictional afterslip on the subduction megathrust, with a major fraction of this slip in the up-dip direction from the main rupture. Eleven months after the main shock, afterslip continues at rates several times the average interseismic rate, resulting in deformation equivalent to at least a Mw 8.2 earthquake. In general, along-strike variations in frictional behavior appear to persist over multiple earthquake cycles. Aftershocks cluster along the boundary between the region of coseismic slip and the up-dip creeping zone. We observe that the cumulative number of aftershocks increases linearly with postseismic displacements; this finding suggests that the temporal evolution of aftershocks is governed by afterslip.