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Published November 2010 | Supplemental Material
Journal Article Open

Complex rupture during the 12 January 2010 Haiti earthquake

Abstract

Initially, the devastating M_w 7.0, 12 January 2010 Haiti earthquake seemed to involve straightforward accommodation of oblique relative motion between the Caribbean and North American plates along the Enriquillo–Plantain Garden fault zone. Here, we combine seismological observations, geologic field data and space geodetic measurements to show that, instead, the rupture process involved slip on multiple faults. Primary surface deformation was driven by rupture on blind thrust faults with only minor, deep, lateral slip along or near the main Enriquillo–Plantain Garden fault zone; thus the event only partially relieved centuries of accumulated left-lateral strain on a small part of the plate-boundary system. Together with the predominance of shallow off-fault thrusting, the lack of surface deformation implies that remaining shallowshear strain will be released in future surface-rupturing earthquakes on the Enriquillo–Plantain Garden fault zone, as occurred in inferred Holocene and probable historic events. We suggest that the geological signature of this earthquake—broad warping and coastal deformation rather than surface rupture along the main fault zone—will not be easily recognized by standard palaeoseismic studies. We conclude that similarly complex earthquakes in tectonic environments that accommodate both translation and convergence—such as the San Andreas fault through the Transverse Ranges of California—may be missing from the prehistoric earthquake record.

Additional Information

© 2010 Macmillan Publishers Limited. Received 24 May 2010; Accepted 09 September 2010; Published online 10 October 2010. We thank V. Tsai, H. Benz, J. McCarthy, R. Bilham and three anonymous reviewers for their comments in improving this manuscript. The study benefited greatly from the assistance of P. Jean of Le Bureau des Mines et de l'Energie d'Haiti, and from the logistical aid of R. Boyer. We thank K. Ludwig and J. Kindinger of USGS and the captain and crew of the RV Endeavor for use and transport of the rigid-hulled inflatable boat. We thank G. Choy for the first-motion focal mechanism. We thank R. Bilham and R. Koehler for early field observations of coastal deformation. Fieldwork studies were sponsored by the US Agency for International Development, USGS and the National Science Foundation. PALSAR level 1.0 data are shared among PIXEL (PALSAR Interferometry Consortium to Study our Evolving Land Surface), and provided from the Japanese Aerospace Exploration Agency under a cooperative research contract with the Earthquake Research Institute, University of Tokyo. Early PALSAR data were provided under the Group on Earth Observation Geohazards Supersite programme and other scenes through the Alaska Satellite Facility. The ownership of PALSAR data belongs to METI (Ministry of Economy, Trade and Industry) and the Japanese Aerospace Exploration Agency. G.P.H. is contracted to work for the USGS by Synergetics Inc., Fort Collins, Colorado. A.S. and M.S. are partially supported under funds provided by the Gordon and Betty Moore Foundation through the Tectonics Observatory. This paper is Caltech Tectonic Observatory contribution 138. Part of the research described in this publication was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. Figures have been made using the Generic Mapping Tools of Wessel and Smith23. Fieldwork partially supported by NSF-EAR RAPID grant 1024990. UTIG contribution no. 2285.

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Created:
August 22, 2023
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October 20, 2023