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The tectonics and active faulting of Haiti from seismicity and tomography

The tectonics and active faulting of Haiti from seismicity and tomography
The tectonics and active faulting of Haiti from seismicity and tomography
Oblique convergence of the Caribbean and North American plates has partitioned strain across a major transpressional fault system that bisects the island of Hispaniola. The devastating MW 7.0, 2010 earthquake that struck southern Haiti, rupturing an unknown fault, highlighted our limited understanding of regional fault segmentation and its link to plate boundary deformation. Here we assess seismic activity and fault structures across Haiti using data from 33 broadband seismic stations deployed for 16‐months. We use travel‐time tomography to obtain relocated hypocenters and models of Vp and Vp/Vs crustal structure. Earthquake locations reveal two clusters of seismic activity. The first corresponds to aftershocks of the 2010 earthquake and delineates faults associated with that rupture. The second cluster shows shallow activity north of Lake Enriquillo (Dominican Republic), interpreted to have occurred on a north‐dipping thrust fault. Crustal seismic velocities show a narrow low‐velocity region with an increased Vp/Vs ratio (1.80‐1.85) dipping underneath the Massif de la Selle, which coincides with a southward‐dipping zone of hypocenters to a depth of 20 km beneath southern Haiti. Our observations of seismicity and crustal structure in southern Haiti suggests a transition in the Enriquillo fault system from a near vertical strike‐slip fault along the Southern Peninsula to a southward‐dipping oblique‐slip fault along the southern border of the Cul‐de‐Sac‐Enriquillo basin. This result, consistent with recent geodetic results but at odds with the classical seismotectonic interpretation of the Enriquillo fault system, is an important constraint in our understanding of regional seismic hazard.
0278-7407
Possee, Daniel
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Keir, Derek
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Harmon, Nicholas
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Rychert, Catherine
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Rolandone, Frédérique
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Leroy, Sylvie
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Corbeau, Jordane
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Stuart, Graham
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Calais, Eric
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Illsley-Kemp, Finnigan
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Boisson, Dominique
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Momplaisir, Roberte
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Prépetit, Claude
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Possee, Daniel
30c7e9de-c298-469e-a9ae-c1c1caf910dc
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Rolandone, Frédérique
5adfaa49-10e8-40d8-bace-bee9dd39f95a
Leroy, Sylvie
627c503b-1036-41fc-a24c-3d09954fab0a
Corbeau, Jordane
a71d8ba4-f19d-43ac-9c4e-ddcef42ff745
Stuart, Graham
e3faae46-fef1-45f4-94cd-50bd675fae92
Calais, Eric
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Illsley-Kemp, Finnigan
c24ef4cb-cbf9-4a58-af8d-da9c7eabd84d
Boisson, Dominique
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Momplaisir, Roberte
8707114c-90ad-46d3-af3a-10decf89c7ac
Prépetit, Claude
6ab89f7a-2d0c-4247-a5e4-0ab688864c8c

Possee, Daniel, Keir, Derek, Harmon, Nicholas, Rychert, Catherine, Rolandone, Frédérique, Leroy, Sylvie, Corbeau, Jordane, Stuart, Graham, Calais, Eric, Illsley-Kemp, Finnigan, Boisson, Dominique, Momplaisir, Roberte and Prépetit, Claude (2019) The tectonics and active faulting of Haiti from seismicity and tomography. Tectonics. (doi:10.1029/2018TC005364).

Record type: Article

Abstract

Oblique convergence of the Caribbean and North American plates has partitioned strain across a major transpressional fault system that bisects the island of Hispaniola. The devastating MW 7.0, 2010 earthquake that struck southern Haiti, rupturing an unknown fault, highlighted our limited understanding of regional fault segmentation and its link to plate boundary deformation. Here we assess seismic activity and fault structures across Haiti using data from 33 broadband seismic stations deployed for 16‐months. We use travel‐time tomography to obtain relocated hypocenters and models of Vp and Vp/Vs crustal structure. Earthquake locations reveal two clusters of seismic activity. The first corresponds to aftershocks of the 2010 earthquake and delineates faults associated with that rupture. The second cluster shows shallow activity north of Lake Enriquillo (Dominican Republic), interpreted to have occurred on a north‐dipping thrust fault. Crustal seismic velocities show a narrow low‐velocity region with an increased Vp/Vs ratio (1.80‐1.85) dipping underneath the Massif de la Selle, which coincides with a southward‐dipping zone of hypocenters to a depth of 20 km beneath southern Haiti. Our observations of seismicity and crustal structure in southern Haiti suggests a transition in the Enriquillo fault system from a near vertical strike‐slip fault along the Southern Peninsula to a southward‐dipping oblique‐slip fault along the southern border of the Cul‐de‐Sac‐Enriquillo basin. This result, consistent with recent geodetic results but at odds with the classical seismotectonic interpretation of the Enriquillo fault system, is an important constraint in our understanding of regional seismic hazard.

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Accepted/In Press date: 22 February 2019
e-pub ahead of print date: 5 March 2019

Identifiers

Local EPrints ID: 429581
URI: https://eprints.soton.ac.uk/id/eprint/429581
ISSN: 0278-7407
PURE UUID: 2b9729a1-7b63-4e4f-85ce-007310fa0338
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X
ORCID for Finnigan Illsley-Kemp: ORCID iD orcid.org/0000-0002-7114-033X

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Date deposited: 29 Mar 2019 17:30
Last modified: 05 Sep 2019 04:01

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