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Geophysics Seminar, Yan Yang (Caltech) - Spatiotemporal Imaging of the Earth’s Near Surface with Fiber-Optic Sensors

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Understanding the Earth's subsurface is essential for mitigating natural hazards and ensuring environmental sustainability. Seismological methods, which measure seismic velocity (v) and its relative temporal changes (dv/v), provide a 4D (space-time) view of the subsurface. However, high-resolution imaging and monitoring of the near surface—the top tens of meters subject to rapid spatiotemporal changes—remains challenging. This is primarily due to the prohibitive costs of dense seismic arrays necessary for capturing high-frequency signals that can probe shallow depths.

Distributed Acoustic Sensing (DAS) offers an affordable solution by converting telecommunication fiber-optic cables into ultra-dense seismic arrays. When combined with seismic ambient noise interferometry, DAS enables time-lapse imaging of the near surface. In this talk, we present a case study using a DAS array in Ridgecrest, California, demonstrating a comprehensive spatiotemporal imaging approach for the near surface. The results provide new insights into high-resolution urban seismic hazard mapping and vadose zone soil moisture monitoring during California's drought periods



Yan Yang is currently a 5th-year Ph.D. student in geophysics at the Caltech Seismolab. She earned her Bachelor's degree in 2016 and her Master's degree in 2019, both in geophysics, from the University of Science and Technology of China. Her research interests are centered on structural imaging using large seismic datasets and advanced technologies, including distributed acoustic sensing and machine learning.


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