# Investigating Supershear Rupture Signatures Through Dynamic Rupture Modeling and Optical Image Correlation of the 2025 Mw 7.7 Mandalay Earthquake, Myanmar

Lucia Andreuttiova, Marion Thomas

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Lucia Andreuttiova, Marion Thomas. Investigating Supershear Rupture Signatures Through Dynamic Rupture Modeling and Optical Image Correlation of the 2025 Mw 7.7 Mandalay Earthquake, Myanmar. 29ème Réunion des Sciences de la Terre 2025, Société géologique de France, Oct 2025, Montpellier, France. pp.666266. hal-05379539

HAL Id: hal-05379539

https://hal.science/hal-05379539v1

Submitted on 24 Nov 2025

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Distributed under a Creative Commons Attribution 4.0 International License
Investigating Supershear Rupture Signatures
Through Dynamic Rupture Modeling and Optical
Image Correlation of the 2025 Mw 7.7 Mandalay
Earthquake, Myanmar

Lucia Andreuttiova*¹ and Marion Thomas

¹University of Rennes – Université de Rennes I – France

Résumé

The 2025 Mw 7.7 earthquake has been identified as a supershear rupture. This conclu-
sion is drawn primarily from rupture models and seismic data. However, to determine the
precise location of this transition remains challenging, largely due to the limited resolution of
available datasets. Nevertheless, numerical models of dynamic ruptures have shown that the
transition to supershear speeds is associated with a reduction in the width of distributed off-
fault deformation. While some geodetic studies also supported this relationship, they were
conducted at relatively low resolution. Therefore, a high-resolution investigation is required
to validate these findings.

We use combination of optical image correlation and dynamic rupture models to under-
stand the location of the transition from sub shear to supershear speed. First we simulate
the 2025 Myanmar earthquake using thermodynamically based micro-mechanical model of
brittle failures. This model takes into account pre-existing deformation and is capable to
simulate the extent and properties of the inelastic off-fault deformation created during an
earthquake event. The model is integrated in source 2D Spectral Element code (sem2dpack)
and simulates earthquake ruptures along a geometrically complex fault system.

Subsequently we use optical image correlation to orthorectify and correlate very high resolu-
tion satellite imagery (Pleiades, SPOT 6) and correlate the pre and post earthquake datasets
using open source photogrammetry and remote sensing software (ASP, Cosi-Corr, MicMac).
The results of optical image correlation is NS and EW displacement map from which we
extract rectangular profiles and measure the width of the fault zone along the part of the
earthquake rupture.

A direct comparison and consistency among field observations, dynamic rupture models, and seismic data indicate that the model is both robust and well validated. In addition, a distinct gap in distributed deformation provides critical empirical evidence for the occurrence of a supershear transition. Together, these findings establish a stronger link between geodetic observations and dynamic rupture models, improve constraints on the transition zone, and offer new insights into the fault properties that may facilitate the shift from subshear to supershear rupture velocities.

**Mots-Clés:** supershear rupture, remote sensing, active tectonics, Myanmar earthquake, rupture
models

<footnote>*Intervenant</footnote>