Figure: Preferred dynamic rupture model for the 2020 Mw 7.2 Haiti earthquake. The initial conditions include lateral variations in regional stresses combined with data-constrained stress heterogeneities and fault strength variations: a) Final slip distribution of the simulation. Slip patches concentrate compactly on the Thrust Fault (TF) and Ravine du Sud Fault (RSF). Slip on the RSF indicates successful rupture transfer b) source time function comparison between observations (grey) and model (purple), showing a good agreement in the moment magnitude and timing. The two distinct peaks in the source time function correspond to the rupture of the TF and RSF, respectively. c) Observed InSAR comparison with simulated LOS surface deformation data. Modeled surface deformation data closely matches the pattern and amplitude of the observations, with the synthetic descending LOS deformation (D138) showing the expected lobe of positive deformation in the LOS direction.

Geo-INQUIRE Transnational Access Project Report: Haiti-drm from Zoe Yin (UCSD, U.S.)

Geo-INQUIRE installation: SeisSol-ExaHyPE - Earthquake simulation, wave simulation and hyperbolic PDE systems (TA2-531-1)

Project title: Using InSAR-derived secondary fault structures to constrain a dynamic rupture model of the 2021 M7.2 Haiti earthquake

Transnational access principal investigator: Zoe Yin (University of California San Diego, U.S.)

Project acronym: Haiti-drm

Project report ID: C1_TA2-531-1_2 (1st Call)

Transnational access team: Dr. Mathilde Marchandon, Prof. Dr. Alice-Agnes Gabriel, Iris Christadler (Ludwig-Maximilians-Universität München (LMU), Germany) 

Date of visit: June 2024

Links: 

 

Project report:

The 2021 Mw 7.2 Haiti earthquake was a devastating event which occurred within the Enriquillo Plantain Garden Fault Zone (EPGFZ). It is not well-understood why neither the 2021 nor the prior 2010 Mw 7.0 earthquake were purestrike slip events and, instead, ruptured with distinct patches of dip slip and strike slip motion on largely separate fault planes.

During her stay in LMU, Zoe has learnt to use SeisSol and started developing dynamic rupture simulations for the 2021 Haiti earthquake. We first built a detailed fault system geometry comprising 17 fault segments, which includes the two main faults that broke during the earthquake (an unnamed Thrust Fault and Ravine du Sud Fault), along with surrounding regional and secondary faults. Zoe then developed a set of dynamic rupture scenarios to evaluate under which conditions the peculiar characteristics of the event could be reproduced.

We find that along-strike changes in the frictional strength of the Thrust Fault as well as lateral changes in the regional stress shape and orientation are key to reproducing the rupture transfer from the Thrust Fault to the Ravine du Sud Fault, the slip rake partitioning, the main characteristics of the InSAR surface deformation, and the multi-peak source time function. The best-fit model is shown in Figure 1.

Zoe’s results have been submitted to Journal of Geophysical Research: Solid earth (preprint: https://eartharxiv.org/repository/view/8231/).