SCEC Award Number 25232 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Improvement and Harmonization of Optical Observations of the Coseismic Fault Zone Deformation Towards an Enhanced Understanding of the Shallow Fault Zone Behavior
Investigator(s)
Name Organization
Jean-Philippe Avouac California Institute of Technology
SCEC Milestones A1-2, B2-1 SCEC Groups FARM
Report Due Date 03/15/2026 Date Report Submitted 10/10/2026
Project Abstract
 In line with the objective “Improving observations and closing critical data gaps” from the 2025 SCEC Science Plan, this project supported the development of new functionalities, documentation and tutorials for Cosi-Corr+ to become a complete, user-friendly, and open-source package for performing fast, optimized, and precise 3D satellite optical image cross-correlation. We used case studies to demonstrate the efficiency and accuracy of Cosi-Corr+, and explore the impact of these observations on the understanding of the processes. We applied the COSICorr+ method in particular to the case of the 2025 Mw7.7 Mandalay, Myanmar earthquake. Our measurements revealed a 700-km long, straight and continuous surface rupture, making it the largest continental rupture ever observed (Antoine et al, PNAS, 2025). These measurements were combined with SAR measurements to produce 3D displacements. These 3D displacement data were inverted to infer the fault geometry at depth, and produce a finite-fault model representing the distribution of slip on the fault at depth. The surface offsets were next used to constrain a quasi-dynamic model of the Sagaing Fault earthquake cycle which reproduces sequences of earthquakes including events similar to the 2025 earthquake.
Intellectual Merit The COSI-Corr+ project has contributed to SCEC's intellectual merit by providing an open source software to measure ground deformation. The measurement of co-seismic deformation has advanced our understanding of earthquake sources by providing constraints on co-seismic slip distribution. These measurement have been be used to constrain the evolution of fault friction during seismic slip which is a central piece of physics needed to develop dynamic models of the earthquake cycle.
Broader Impacts The project has contributed to the broader impacts of SCEC by promoting educational opportunities, fostering mentoring and training at Caltech, encouraging cross-collaboration within the SCEC community, and reaching out to educate our local communities.
Additionally, the project has strengthened research infrastructure through enhanced data-sharing networks and collaborators and provided valuable societal benefits by advancing efforts in earthquake preparedness.
Project Participants Solène Antoine, a postdoctoral fellow in the PI's group at Caltech, performed most of the work.
Exemplary Figure Figure 1. North-South (NS) surface displacement associated with the 2025 earthquake from the correlated Sentinel2 images. (b) Fault-parallel surface offsets (c) Horizontal extend of past ruptures documented by Wang et al., (2014) and of the 2025 rupture (this study). Horizontal distribution of the events reflects their relative chronology. From Antoine et al. (PNAS, 20025)
Linked Publications

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