Tectonic Model of the 2021 Haiti Earthquake Based on a Newly‐Formed Strike‐Slip Bypass Fault Across a Paired Restraining‐Releasing Bend

Abstract

On 14 August 2021, the southern peninsula of Haiti was struck by an M _w 7.2 earthquake that killed more than 2,200 people. The 2021 epicenter is located 95 km west of the M _w 7.0 2010 Haiti earthquake and 7 km north of the main, geomorphic trace of the EW‐striking, left‐lateral strike‐slip Enriquillo‐Plantain Garden fault zone (EPGFZ) that forms a transpressional plate boundary between the Caribbean plate and the Gonâve microplate. Using a compilation of earthquake focal mechanism solutions, aftershocks, interferograms and coseismic displacements from ALOS‐2 and Sentinel‐1 Interferometric Synthetic Aperture Radar (InSAR), we propose that the 2021 earthquake ruptured a 2.5‐km wide band of steeply north‐dipping, secondary faults that bypassed the geomorphic prominent and curved 60‐km long restraining‐releasing paired bend on the EPGFZ. The initiating sub‐event of the 2021 mainshock is a left‐lateral and oblique thrusting event; that was followed by a left‐lateral westward‐propagating strike‐slip sub‐event along the proposed 65°N–77° N‐dipping Ravine du Sud bypass fault zone. We test our hypothesis by comparing two finite fault models that are constrained by the InSAR and global navigation satellite system displacements both on and off the bypassed restraining‐releasing paired bend on EPGFZ. We then compare our proposed model for fault evolution of the EPGFZ with similar examples of strike‐slip fault systems at a variety of map scales that are characterized by the same type of fault‐straightening process as we propose here for the 2021 Haiti earthquake.