Seismotectonics of southern Haiti: A new faulting model for the 12 January 2010 M7.0 earthquake

The prevailing consensus is that the 2010M(w)7.0 Haiti earthquake left the Enriquillo-Plantain Garden strike-slip fault ( EPGF) unruptured but broke unmapped blind north dipping thrusts. Using high-resolution topography, aerial images, bathymetry, and geology, we identified previously unrecognized south dipping NW-SE striking active thrusts in southern Haiti. One of them, Lamentin thrust, cuts across the crowded city of Carrefour, extends offshore into Port-au-Prince Bay, and connects at depth with the EPGF. We propose that both faults broke in 2010. The rupture likely initiated on the thrust and propagated further along the EPGF due to unclamping. This scenario is consistent with geodetic, seismological, and field data. The 2010 earthquake increased the stress toward failure on the unruptured segments of the EPGF and on neighboring thrusts, significantly increasing the seismic hazard in the Port-au-Prince urban area. The numerous active thrusts recognized in that area must be considered for future evaluation of the seismic hazard.