A magnitude 7.0 earthquake struck Haiti on January 12, 2010, causing intense damage in the capital Port-au-Prince. The event occurred on the Enriquillo-Plantain Garden fault zone one of the main faults that accommodates the relative motion between the Caribbean and North American plates. In this project, a research team composed of scientists from Purdue University, University of Texas, University of Arkansas, and the Haitian Bureau of Mines and Energy will map and precisely measure the displacement on the fault, re-measure an existing network of 30 GPS benchmarks in Haiti and the Dominican Republic to determine co-seismic deformation, and install continuous GPS instruments in key locations to measure post-seismic deformation. Available radar data for the area will be used to compute co-seismic interferograms. The information gathered in the field will be integrated to determine the co-seismic displacement during the main shock of January 12 and to understand the nature and mechanism of the post-seismic deformation that will follow this event for some years in the future. Geodetic measurements must be done as early as possible after the main shock in order to capture the early phases of post-seismic deformation. Also, it is key that geodetic measurements for co-seismic displacements include as little post-seismic signal as possible, hence requiring a survey very soon after the event. In addition, mapping and quantifying fault displacement must be done immediately because fault offsets are ephemeral and typically disappear quickly as the people begin to repair roads, fences, and other offset strain markers.
This project is an unprecedented opportunity to study a large, shallow-focus strike-slip event in a tectonic environment similar to other plate boundaries that have not recently experienced such an event, such as the San Andreas Fault system. Indeed, this particular detailed study of the post-seismic response of this event may prove most beneficial as the Enriquillo-Plantain Garden fault zone crosses thicker continental crust in Hispaniola and thinner ocean crust to the west toward Jamaica. Because Coulomb stress changes from the January 12 event have loaded both extremities of the rupture this work will help define the likelihood that other large earthquakes may be impending along that fault system. The project is supported by the NSF Earth Sciences Division Tectonics and Geophysics Programs and the NSF Office of International Science and Engineering.
On January 12, 2010, a Mw7.0 earthquake struck the Port-au-Prince region of Haiti, killing more than 200,000 people and causing an estimated $8 billion in damages. The level of devastation was largely due to the earthquake striking a heavily populated region of a poor country with substandard building practices, unprepared for such an eventually. The earthquake occurred within the boundary between two major tectonic plates, Caribbean and North America, the locus of several large historical earthquakes since Columbus first landed on the island of Hispaniola. Taken together, the geological, seismological, and geodetic data acquired shortly after the event indicate that the earthquake was caused by a ~30 km long rupture between Petit Goave and Greissier, extending from 5 to about 20 km depth, dipping 60o to the north, with 2/3 strike-slip and 1/3 contractional motion. The event is consistent with the accumulation of elastic strain measured using geodetic data across Haiti and the rest of teh northeastern Caribbean since 2003. The earthquake was followed by a strong sequence of aftershocks, most of them located at the western termination of the rupture, with magnitudes reaching 5.9 and mechanisms indicating pure NE-SW contractional motion. Much remains to be learned about the Haiti earthquake, a tragic reminder that earthquake risk mitigation must be accounted for in all aspects of the country’s reconstruction.
