Investigating the crustal structure and fault geometry of the 2021 Haiti earthquake

University Of California-Riverside, Riverside CA

Investigators

Abstract

Haiti is extremely vulnerable to large earthquakes. The M7.0 2010 and M7.2 2021 earthquakes in Haiti caused more than 200,000 and 2,000 deaths, respectively. The better we understand past earthquakes, identify active faults, and pinpoint locations with possible strong ground shaking, the more we can do to prevent future tragedy. This project will allow seismologists at the University of California, Riverside to clearly identify which faults ruptured during the 2021 earthquake, and find areas where strong ground shaking is most likely to occur during future large earthquakes. Detecting and locating aftershocks will help delineate the faults that ruptured in 2021, as well as other active faults. Mapping out how seismic velocities in the crust vary in 3D will bring to light regions with unusually slow seismic velocities, which indicate softer rocks and hence amplified shaking during an earthquake. This project will engage local Haitian scientists to have a lasting impact on local earthquake monitoring for seismic hazard assessment. The project will also engage young Haitian students, in the hope that some will be inspired to pursue careers in the geosciences. The 2021 M7.2 Haiti earthquake, which struck a decade after the devastating 2010 earthquake, occurred within the network of faults comprising the Enriquillo Plantain Garden Fault Zone (EPGFZ) in southern Haiti. Preliminary geodetic observations suggest that this earthquake is similar to the 2010 event where left-lateral strike-slip occurred on the western part of the rupture and reverse slip on the eastern part. Initial aftershock locations from the regional seismic network are too diffuse to confirm this hypothesis, and it is not clear whether this event occurred on the main fault or on secondary faults. Furthermore, considering that heavy damage from the 2010 earthquake occurred primarily in a sedimentary basin with low seismic velocities that amplified seismic shaking, it is possible that areas experiencing high levels of damage from the 2021 earthquake are also underlain by such material. Using newly available data from seismic stations that were deployed following the 2021 earthquake, we will apply innovative techniques to detect and locate the aftershocks with high precision, and investigate the 3D crustal velocity structure in that region. This project will directly impact research and education by offering research opportunities for local undergraduate students from underrepresented groups within the U. C. Riverside community. The project will also benefit the people of Haiti by engaging local Haitian scientists to have a lasting impact on local earthquake monitoring for seismic hazard assessment, and providing opportunities to young Haitian students so that they can inspire future generations to pursue careers in geosciences. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.