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Dynamically triggered slip on a splay fault in the M_w 7.8, 2016 Kaikoura (New Zealand) earthquake

Hollinsworth, James and Ye, Lingling and Avouac, Jean-Philippe (2017) Dynamically triggered slip on a splay fault in the M_w 7.8, 2016 Kaikoura (New Zealand) earthquake. Geophysical Research Letters, 44 (8). pp. 3517-3525. ISSN 0094-8276. http://resolver.caltech.edu/CaltechAUTHORS:20170320-124537893

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Abstract

We investigate the Mw 7.8, 2016 Kaikoura (New Zealand) earthquake using optical satellite imagery and seismology to reveal the main features of the rupture process. Correlation of Landsat8 images reveals a 30-40 km surface rupture on the Kekerengu Fault and Jordan Thrust, with up to 12 m of right-lateral slip. A previously unrecognized conjugate strike-slip fault, the Papatea Fault, also slipped co-seismically (3-4 m). The global CMT centroid indicates both thrust and right-lateral slip, and is located ~100 km NE of the mainshock epicenter. The significant non-double-couple component of the gCMT (25%) suggests the mainshock is not well represented by a single planar fault. Back-projection of teleseismic P waves reveals two main bursts of seismic radiation: (1) at 10-20 s, near the mainshock epicenter, and (2) at ~70 s, close to the observed surface ruptures. We determine a finite source kinematic model of the rupture from the inversion of seismic waveforms. We use two faults in our model, defined to match the observed slip on the Kekerengu Fault, and a deeper offshore fault with a lower dip angle to satisfy the long period seismological observations. We compute the equivalent moment tensor from our finite source model and find it to be remarkably consistent with the gCMT solution. Although little is known about the geometry of these faults at depth, if the Kekerengu fault splays from the deeper thrust, it provides a rare example where the contribution of slip on a splay fault can be clearly isolated in the seismological waveforms.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1002/2016GL072228DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2016GL072228/abstractPublisherArticle
ORCID:
AuthorORCID
Hollinsworth, James0000-0003-0122-296X
Ye, Lingling0000-0002-8739-2072
Avouac, Jean-Philippe0000-0002-3060-8442
Additional Information:© 2017 American Geophysical Union. Received 6 DEC 2016; Accepted 13 MAR 2017; Accepted article online 20 MAR 2017; Published online 21 APR 2017. Landsat8 satellite imagery was obtained from the USGS (earthexplorer.usgs.gov/). Seismic data were obtained from the Australian seismic network. Financial support is acknowledged from SCEC (L.Y. and J.P.A.), CNRS, and ISTerre (J.H.). We thank Francois Ayoub, Zacharie Duputel, Romain Jolivet, and James Dolan for helpful discussions. Various images in this paper were created by using the Generic Mapping Tools (GMT) software [Wessel and Smith, 1998].
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Southern California Earthquake Center (SCEC)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Institut des Sciences de la TerreUNSPECIFIED
Subject Keywords:earthquake; New Zealand; rupture; correlation; seismology; slip inversion
Record Number:CaltechAUTHORS:20170320-124537893
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170320-124537893
Official Citation:Hollingsworth, J., L. Ye, and J.-P. Avouac (2017), Dynamically triggered slip on a splay fault in the Mw 7.8, 2016 Kaikoura (New Zealand) earthquake, Geophys. Res. Lett., 44, 3517–3525, doi:10.1002/2016GL072228
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75244
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:27 Mar 2017 16:34
Last Modified:03 Jun 2017 00:04

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