Surface Deformation Surrounding the 2021 Mw 7.2 Haiti Earthquake Illuminated InSAR Observations

Earthquakes pose a major threat to the people of Haiti, as tragically shown by the cata-strophic 2010 Mw 7.0 earthquake and more recently by the 2021 Mw 7.2 earthquake. Both events occurred within the transpressional Enriquillo-Plantain Garden fault zone (EPGFZ), which runs through the southern peninsula of Haiti and is a major source of seismic hazard for the region. Satellite-based Interferometric Synthetic Aperture Radar (InSAR) data are used to illuminate the ground deformation patterns associated with the 2021 event. The analysis of Sentinel-1 and Advanced Land Observation Satellite (ALOS)-2 InSAR data shows (1) the broad coseismic deformation field; (2) detailed secondary fault structures as far as 12 km from the main Enriquillo-Plantain Garden fault (EPGF), which are active during and after the earthquake; and (3) postseismic shallow slip, which migrates along an similar to 40 km unruptured section of the EPGF for approximately two weeks following the earth-quake. The involvement of secondary faults in this rupture requires adjustments to the rep-resentation of hazard that assumes a simple segmented strike-slip EPGF. This work presents the first successful use of phase gradient techniques to map postseismic deformation in a vegetated region, which opens the door to future studies of a larger number of events in a wider variety of climates.