Complex Rupture and Triggered Aseismic Creep During the 14 August 2021 Haiti Earthquake From Satellite Geodesy

The 2021 August 14 MW 7.2 Nippes, Haiti earthquake occurred 75 km west of the epicenter of the 2010 Leogane earthquake (Haiti) on the transpressive Caribbean ‐ North America plate boundary. We present an updated fault map for Hispaniola and model coseismic and early postseismic fault slip using Interferometric Synthetic Aperture Radar and pixel offsets. We find the earthquake ruptured multiple segments of the Enriquillo‐Plantain Garden Fault Zone. Slip occurred in two main sub‐events on either side of a restraining bend at Pic Macaya, with ∼2.7 m of peak reverse‐slip east of the bend. To the west, slip jumps the restraining bend and further ruptures with ∼1.2 m of left‐lateral slip. Afterslip in the 4 days following the event occurred at shallow depth and adjacent to the coseismic rupture areas and reached the surface east of Pic Macaya. Plain Language Summary On 14 August 2021, a large MW7.2 earthquake struck southwestern Haiti, 75 km to the west of the 2010 Leogane, Haiti earthquake. We use remotely‐sensed data from two Synthetic Aperture Radar missions, ALOS‐2 and Sentinel‐1, and a new fault map database to study the earthquake and try to determine which faults slipped and where, and how much. We built a model of fault slip during the earthquake and aseismic slip that followed the earthquake, called afterslip. By comparing our results with previously published results using seismic data, we suggest that the earthquake started out with reverse slip on the Enriquillo‐Plantain Garden Fault Zone (EPGFZ) near the hypocenter. It then jumped the restraining bend in the EPGFZ near Pic Macaya, and ruptured west of the restraining bend with left‐lateral slip. The earthquake appears to be very complex and ruptured multiple faults. Afterslip in the 4 days following the earthquake was nearly as large as the earthquake, reaching the surface after ∼3 days. Taken together, the modeling results paint a picture of a complex fault system with highly variable stress and stability. Key Points The 2021 Haiti earthquake ruptured the Enriquillo‐Plantain Garden Fault as thrust slip east of Pic Macaya and left‐lateral slip to the west Slip occurred on multiple fault segments and jumped across the restraining bend at Pic Macaya InSAR observations indicate afterslip in the 4 days following the event of a similar magnitude to the coseismic slip