|Title||Frictional Afterslip Following the 2005 Nias-Simeulue Earthquake, Sumatra|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Hsu Y-J, Simons M, Avouac J-P, Sieh K, Galetzka J, Chlieh M, Natawidjaja DH, Prawirodirdjo L, Bock Y|
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.