title: Frictional afterslip following the 2005 Nias-Simeulue earthquake, Sumatra.
abstract: 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 M(w) 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.
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. yaru@gps.caltech.edu
authors.forename: Ya-Ju
authors.initials: YJ
authors.lastname: Hsu
authors.forename: Mark
authors.initials: M
authors.lastname: Simons
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Avouac
authors.forename: John
authors.initials: J
authors.lastname: Galetzka
authors.forename: Kerry
authors.initials: K
authors.lastname: Sieh
authors.forename: Mohamed
authors.initials: M
authors.lastname: Chlieh
authors.forename: Danny
authors.initials: D
authors.lastname: Natawidjaja
authors.forename: Linette
authors.initials: L
authors.lastname: Prawirodirdjo
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Bock