Evolving tidal modulation of seismicity before and after the 2019 Ridgecrest earthquake: Implications for the physics of preparatory processes?
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Eric Beaucé
Lamont-Doherty Earth Observatory, Columbia University
- Date & Time
- Location
- Hybrid In Person and Online seminar via Microsoft Teams
- Host
- Theresa Sawi
- Summary
Do the solid Earth tides influence seismicity? If yes, what can we learn about earthquake physics? After more than a century of exploration, much remains to be understood about these questions. The new generation of earthquake catalogs, or "enhanced" catalogs, made possible by the increasing amount of seismic data, great advances in earthquake detection techniques and more computing power, bring new answers. Here, I present an analysis of tidally modulated seismicity in an enhanced catalog, built with deep learning techniques and other physics-based tools, covering the Ridgecrest, California area and ranging from 2008 to 2024, thus including about a decade of seismicity before the 2019 M7.1 Ridgecrest earthquake. I show how dense observations and novel analysis techniques enable the detection of the increasingly strong modulation of seismicity before the mainshock, followed by a drop. Perhaps more importantly, I show that the modulation regime changes before the mainshock. These observations bear outstanding implications for earthquake physics and physics-based forecasting. I explore possible physical mechanisms using deep slip and the dilatancy-fluid diffusion hypotheses.