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Postseismic Response to the 2021 Haiti Earthquake: Advanced Insar Analysis and Implications for the Triggered Fault Creep

Description: 

The recent August 14, 2021 MW7.2 Nippes earthquake occurred 75 km to the west of the Mw7.0 2010 earthquake that happened near Port-au-Prince, Haiti, both on the Enriquillo-Plaintain Garden fault zone (EPFGZ). The 2021 earthquake left a seismic gap between the two events that has not experienced any large aftershocks from either event. Identifying if and where postseismic deformation occurred on the EPGFZ following the earthquake is a critical step to identify whether the seismic gap on the EPGFZ will be the site of a future MW7 earthquake or will release its strain aseismically (Martin & Hough, 2022).

In this study, we collect multi-temporal data acquired by Sentinel-1 A/B and ALOS-2 satellites and use an advanced InSAR processing approach implemented in FRInGE package (Fattahi et al., 2019) to map early postseismic deformation following the 2021 Haiti mainshock. Fringe exploits the interferometric covariance matrix formed for each distributed scatterer (DS) over its neighborhood and the phase history of each permanent scatterer (PS) to estimate surface deformation at high spatial and temporal resolution. The measured surface displacement in our study reveals the spatiotemporal evaluation of shallow creep along EPGFZ to the east of the epicenter. We use the cumulative displacement map and profiles across the EPGFZ to investigate the behavior of the fault in a short period following the 2021 earthquake and construct models of cumulative slip. In the future, we plan to address the following questions: (1) does the afterslip reflect the stress triggered by the mainshock? (2) based on the InSAR observations, can frictional parameters be calculated on the fault?

References:

Fattahi, H., Agram, P.S., Tymofyeyeva, E. and Bekaert, D.P., 2019. FRInGE; Full-Resolution InSAR timeseries using Generalized Eigenvectors. AGUFM, 2019, pp.G11B-0514.

Martin, S.S. and Hough, S.E., 2022. The 8 April 1860 Jour de Pâques earthquake sequence in southern Haiti. Bulletin of the Seismological Society of America, 112(5), pp.2468-2486.

Session: Active Faults in the Caribbean and Central America

Type: Oral

Date: 4/20/2023

Presentation Time: 09:00 AM (local time)

Presenting Author: Sanaz Vajedian

Student Presenter: No

Invited Presentation: 

Authors