Imaging earthquakes using optical remote sensing at regional and local scale: insights into earthquake source and fault zone deformation processes
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Solène Antoine
California Institute of Technology
- Date & Time
- Location
- Online-only seminar via Microsoft Teams
- Host
- Travis Alongi
- Summary
Optical remote sensing has become key to improving the observation and understanding of earthquakes. With spatial and temporal coverage as well as processing and computational capabilities constantly improving, it is now among the first sources of information after an event. This was the case with the 2025 Mw7.7 Mandalay earthquake for which the global Sentinel-2 missions enabled imaging of earthquake surface displacement only a few days after it happened. Using image correlation methods, we measured the amplitude and spatial distribution of surface slip along the ruptured fault. We used these observations along with SAR measurements to model the earthquake source and make initial assessments of whether the event did or did not comply with existing predictions based on knowledge of the fault and its past seismic activity. We also used these observations to constrain a seismic cycle model of the fault that ruptured in the 2025 event, possibly opening new avenues for assessing seismic hazard on long, continuous, mature fault systems that do not necessarily follow the typical segmented or slip-predictable models. In addition to the global missions, sub-meter resolution imaging capabilities including those from private compagnies allow for three dimensional measurements at a much finer scale, bringing constraints on, for example, the relations between earthquake source, fault geometry, fault slip, off-fault deformation, and lithology. Performing such observations for the 2021 Mw7.4 Maduo earthquake, we show how the localization of the deformation along the surface faults increases with increasing total slip, when integrated along depth, and how this process relates to the so called “shallow slip deficit."