Slip in the 2010-2011 Canterbury Earthquakes, New Zealand

Elliott, J. R. and Nissen, Edwin and England, P. C. and Jackson, James A. and Lamb, Simon and Li, Zhenhong and Oehlers, Michael and Parsons, Barry E. (2012) Slip in the 2010-2011 Canterbury Earthquakes, New Zealand. Journal of Geophysical Research, 117. B03401. DOI 10.1029/2011JB008868

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Abstract

The 3rd September 2010 Mw 7.1 Darfield and 21st February 2011 Mw 6.3 Christchurch (New Zealand) earthquakes occurred on previously unknown faults. We use InSAR ground displacements, SAR amplitude offsets, field mapping, aerial photographs, satellite optical imagery, a LiDAR DEM and teleseismic body-wave modelling to constrain the pattern of faulting in these earthquakes. The InSAR measurements reveal slip on multiple strike-slip segments and secondary reverse faults associated with the Darfield mainshock. Fault orientations are consistent with those expected from the GPS-derived strain field. The InSAR line-of-sight displacement field indicates the main fault rupture is about 45 km long, and is confined largely to the upper 10 km of the crust. Slip on the individual fault segments of up to 8 m at 4 km depth indicate stress drops of 6-10 MPa. In each event, rupture initiated on a reverse fault segment, before continuing onto a strike-slip segment. The non-double couple seismological moment tensors for each event are matched well by the sum of double couple equivalent moment tensors for fault slip determined by InSAR. The slip distributions derived from InSAR observations of both the Darfield and Christchurch events show a 15 km-long gap in fault slip south-west of Christchurch, which may present a continuing seismic hazard if a further unknown fault structure of significant size should exist there.

Item Type: Article
Uncontrolled Keywords: 2012AREP; IA63;
Subjects: 02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Journal of Geophysical Research
Volume: 117
Page Range: B03401
Identification Number: 10.1029/2011JB008868
Depositing User: Sarah Humbert
Date Deposited: 07 Mar 2012 16:02
Last Modified: 23 Jul 2013 10:03
URI: http://eprints.esc.cam.ac.uk/id/eprint/2396

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