Crustal stresses and damage evolve throughout the seismic cycle of the Ridgecrest fault zone
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Jared Bryan
MIT
- Date & Time
- Location
- Online-only seminar via Microsoft Teams
- Summary
Earthquake sequences reorganize crustal stress and damage over depth and time. I will present time-lapse teleseismic receiver function measurements, jointly interpreted with GNSS data, to track the 2019 Ridgecrest sequence from the surface to depths of ~20 km. We find a ~2% coseismic wavespeed reduction shallower than ~10 km that heals within months, while a deeper decrease at ~10–15 km accumulates post-seismically and persists for years. Concurrently, the receiver function-inferred fast-axis of anisotropy rotates by up to ~10° and evolves along with fault-parallel GNSS displacement rates, indicating localized semi-brittle or fluid-assisted deformation at depth. These observations imply a depth-dependent rheology that decouples rapid shallow healing from longer-lived deep changes, with two end-member outcomes: slow inter-seismic recovery that tracks stress build-up, or persistent structural change in an immature fault zone. I will discuss the implications for stress accumulation, energy partitioning, and how we interpret shallow monitoring as a proxy for deep fault-zone evolution. I will also briefly preview ongoing work that uses seasonal hydrological loading as a periodic forcing, interpreting the amplitude and phase of vertical GNSS displacements together with time-variable anisotropy to estimate fault zone rheology and permeability. Preliminary single-station results show an anisotropy response with a measurable phase offset relative to GNSS, with network-wide analysis underway to assess spatial variability.