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Rupture Segmentation of the August 14, 2021 Mw7.2 Nippes, Haiti, Earthquake Using Aftershock Relocation From a Local Seismic Deployment

Description: 

The 14 August 2021 M_w 7.2 Haiti earthquake struck 11 years 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, we installed 12 broadband stations 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 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 Plantain Garden (EPG) fault. Additionally, two smaller aftershock clusters occurred on the EPG 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 transpressional structures illustrated by the aftershock zones.

Session: Active Faults in the Caribbean and Central America

Type: Oral

Date: 4/20/2023

Presentation Time: 08:45 AM (local time)

Presenting Author: Roby Douilly

Student Presenter: No

Invited Presentation: Yes

Authors