Presentation by Dr. Jared Bryan.
Crustal stresses and damage evolve throughout the seismic cycle of the Ridgecrest fault zone
Abstract:
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.
