Seismotectonic context of southern Haiti: a new model for the magnitude Mw7.0 earthquake of January 12th, 2010
Despite the magnitude of the deadly earthquake of January 12th, 2010, the seismotectonic context and active faults in the epicentral zone were still poorly understood.
Publication date: 10/02/2016
General public, Press, Research
Related teams :
Tectonics and Mechanics of the Lithosphere
Related themes : Natural Hazards
The south of the island of Haiti is crossed from east to west by a major strike-slip fault: the Enriquillo-Plantain-Garden Fault (EPGF). Until now, the models proposed for the 2010 earthquake ruled out rupture along this fault. This difficulty in understanding the origin and mechanism of the earthquake is mainly due to the fact that this earthquake, despite its magnitude, was not associated with surface ruptures.
The authors of this new study, published in December 2015, used aerial images, high-resolution topographic data, bathymetry and geological data to identify active faults in the epicentral zone. They showed the existence of a north-west-south-east trending, south-dipping thrust fault to the north of the EPGF, in the bay of Port-au-Prince: the Lamentin thrust fault. This thrust is connected at depth to the EPG fault. The authors suggest that these two faults ruptured during the earthquake. Geodetic data show that the rupture first initiated on the thrust fault and then propagated along the Enriquillo fault.
The study also shows that the Lamentin fault is part of a larger group of thrust faults of the same orientation, some of which have been identified beneath the city of Port-au-Prince. These active faults imply a significant seismic hazard in the city and its conurbation, especially as the authors calculate that Coulomb stresses were increased on some of these faults after the 2010 earthquake.
Ref : Saint Fleur, N., N. Feuillet, R. Grandin, E. Jacques, J. Weil-Accardo, and Y. Klinger (2015), Seismotectonics of southern Haiti: A new faulting model for the 12 January 2010M7.0 earthquake, Geophys. Res. Lett. 42, doi:10.1002/2015GL065505.(https://hal.archives-ouvertes.fr/hal-01214970/document)
