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Piecemeal Rupture of the Mentawai Patch, Sumatra: The 2008 M w 7.2 North Pagai Earthquake Sequence
Author(s) -
Salman Rino,
Hill Emma M.,
Feng Lujia,
Lindsey Eric O.,
Mele Veedu Deepa,
Barbot Sylvain,
Banerjee Paramesh,
Hermawan Iwan,
Natawidjaja Danny H.
Publication year - 2017
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2017jb014341
Subject(s) - geology , seismology , geodesy , submarine pipeline , geodetic datum , interferometric synthetic aperture radar , slip (aerodynamics) , global positioning system , inversion (geology) , synthetic aperture radar , tectonics , geotechnical engineering , remote sensing , physics , computer science , telecommunications , thermodynamics
The 25 February 2008 M w 7.2 North Pagai earthquake partially ruptured the middle section of the Mentawai patch of the Sunda megathrust, offshore Sumatra. The patch has been forecast to generate a great earthquake in the next few decades. However, in the current cycle the patch has so far broken in a sequence of partial ruptures, one of which was the 2008 event, illustrating the potential of the patch to generate a spectrum of earthquake sizes. We estimate the coseismic slip distribution of the 2008 event by jointly inverting coseismic offsets from GPS and interferometric synthetic aperture radar. We then estimate afterslip with 5.6 years of cumulative GPS displacements. Our results suggest that the estimated afterslip partially overlaps the coseismic rupture. The overlap of coseismic rupture and afterslip can be explained conceptually by a simple rate‐and‐state model where the degree of overlapping is controlled by the dynamic weakening and the critical nucleation size in the velocity‐weakening area. Comparing our rate‐and‐state model results with our geodetic inversion results, we suggest that the part of the coseismic rupture that does not overlap with the afterslip may represent a velocity‐weakening region, while the overlapping part may represent a velocity‐strengthening region.