An Unambiguous Signature of Pore Fluid Aftershock Triggering in the Landers Earthquake Sequence
Year: 2024
Type: article
Abstract: Aftershocks within an extensional fault discontinuity of the 1992 Landers, California earthquake rupture occurred at an approximately constant rate for over three years following the mainshock. This contrasts with most of the rest of the aftershock sequence, and aftershock sequences in general, for which aftershock rates decay following Omori’s law. The protracted aftershocks in the fault discontinuity can be understood if pore fluids are present at seismogenic depths and trigger seismicity as they flow to equilibrate pore pressure during the transition from the immediate, undrained to the eventual, drained condition. Changes in pore fluid pressure modulated by changes in the mean normal stress provide a clear and unambiguous signature of fluid effects in earthquake triggering. If this result generalizes to other settings, it suggests a predictable time-dependent component to the pattern of aftershock triggering not accounted for in models of Coulomb static stress triggering.
Source: Annals of Geophysics
DOI: 10.4401/ag-9162
Authors: Gregory Beroza, Eva E. Zanzerkia
Institutions: Stanford University, U.S. National Science Foundation
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W4403462782