Open AccessSource model of the 2009 M w 7.6 Padang intraslab earthquake and its effect on the Sunda megathrust
Author(s) -
Wiseman Kelly,
Banerjee Paramesh,
Bürgmann Roland,
Sieh Kerry,
Dreger Douglas S.,
Hermawan Iwan
Publication year - 2012
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2012.05600.x
Subject(s) - seismology , aftershock , geology , foreshock , interplate earthquake , seismic moment , geodetic datum , fault plane , focal mechanism , geodesy , fault (geology)
SUMMARY We investigate the source of the M w 7.6 Padang earthquake by inverting three‐component global positioning system (GPS) data and broad‐band regional seismic‐displacement waveforms. The earthquake involved oblique‐reverse slip either on an E–W, south‐dipping plane, or on a N–S, west‐dipping plane. Finite‐fault inversions indicate that the rupture primarily propagated downdip and southwest from the hypocentre, with a scalar seismic moment between 3.4 and 3.7 × 10 20 N m ( M w 7.62–7.65). Analysis of the seismic and geodetic data do not allow for unique identification of the causative focal plane. Aftershock patterns strongly suggest the E–W plane was the causative focal plane, but aligned geological structures in the downgoing plate favour the N–S plane. In either case, this unusually large intraslab earthquake has moved closer to failure the deepest portion of the overlying megathrust, which last ruptured during a great earthquake more than two centuries ago and is late in its seismic cycle.