Rupture Segmentation of the August 14, 2021 Mw7.2 Haiti Earthquake Using Aftershock Relocation from a Local Seismic Deployment
Résumé
The 14 August 2021 Mw 7.2 Haiti earthquake struck a decade after the devastating 2010 event within the Enriquillo Plantain Garden Fault Zone in the Southern peninsula of Haiti. Space geodetic results show that the rupture is composed of both left-lateral strike-slip and thrust motion, similar to the 2010 rupture, but aftershock locations from a local short-period network are too diffuse to precisely delineate the segments that participated in this rupture. A few days after the mainshocks, 12 broadband stations were installed in the epicentral area. Here we use data from those stations in combination with 4 local Raspberry Shakes stations that were already in place as part of a citizen seismology experiment to precisely relocate 2528 aftershocks from August to December 2021 and also derive one-dimensional P and S crustal velocity models for this region. We show that the aftershocks delineate three north dipping structures with different strikes, located to the north of the Enriquillo fault. Additionally, two smaller aftershock clusters occurred on the Enriquillo fault near the hypocenter area, indicative of triggered seismicity. Focal mechanisms are in agreement with coseismic slip inversion from InSAR data with nodal planes that are consistent with the structures illustrated by the aftershock zones.