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First direct observation of coseismic slip and seafloor rupture along a submarine normal fault and implications for fault slip history

Escartín, Javier, Leclerc, Frédérique, Olive, Jean-Arthur, Mevel, Catherine, Cannat, Mathilde, Petersen, Sven, Augustin, Nico, Feuillet, Nathalie, Deplus, Christine, Bezos, Antoine, Bonnemains, Diane, Chavagnac, Valérie, Choi, Yujin, Godard, Marguerite, Haaga, Kristian A., Hamelin, Cédric, Ildefonse, Benoit, Jamieson, John W., John, Barbara E., Leleu, Thomas, MacLeod, Christopher John, Massot-Campos, Miquel, Nomikou, Paraskevi, Paquet, Marine, Rommevaux-Jestin, Céline, Rothenbeck, Marcel, Steinführer, Anja, Tominaga, Masako, Triebe, Lars, Campos, Ricard, Gracias, Nuno, Garcia, Rafael, Andreani, Muriel and Vilaseca, Géraud 2016. First direct observation of coseismic slip and seafloor rupture along a submarine normal fault and implications for fault slip history. Earth and Planetary Science Letters 450 , pp. 96-107. 10.1016/j.epsl.2016.06.024

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Abstract

Properly assessing the extent and magnitude of fault ruptures associated with large earthquakes is critical for understanding fault behavior and associated hazard. Submarine faults can trigger tsunamis, whose characteristics are defined by the geometry of seafloor displacement, studied primarily through indirect observations (e.g., seismic event parameters, seismic profiles, shipboard bathymetry, coring) rather than direct ones. Using deep-sea vehicles, we identify for the first time a marker of coseismic slip on a submarine fault plane along the Roseau Fault (Lesser Antilles), and measure its vertical displacement of ∼0.9 m in situ. We also map recent fissuring and faulting of sediments on the hangingwall, along ∼3 km of rupture in close proximity to the fault’s base, and document the reactivation of erosion and sedimentation within and downslope of the scarp. These deformation structures were caused by the 2004 Mw 6.3 Les Saintes earthquake, which triggered a subsequent tsunami. Their characterization informs estimates of earthquake recurrence on this fault and provides new constraints on the geometry of fault rupture, which is both shorter and displays locally larger coseismic displacements than available model predictions that lack field constraints. This methodology of detailed field observations coupled with near-bottom geophysical surveying can be readily applied to numerous submarine fault systems, and should prove useful in evaluating seismic and tsunamigenic hazard in all geodynamic contexts.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Uncontrolled Keywords: submarine fault; surface rupture; earthquake; fault slip; neotectonics; microbathymetry
Publisher: Elsevier
ISSN: 0012-821X
Funders: Natural Environment Research Council
Date of First Compliant Deposit: 21 July 2016
Date of Acceptance: 16 June 2016
Last Modified: 04 Jun 2017 09:17
URI: http://orca.cf.ac.uk/id/eprint/93134

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