Premium
Origin of the Co‐Seismic Variations of Elastic Properties in the Crust: Insight From the Laboratory
Author(s) -
Paglialunga F.,
Passelègue F. X.,
Acosta M.,
Violay M.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl093619
Subject(s) - fault gouge , geology , seismology , seismic wave , amplitude , slip (aerodynamics) , crust , overburden pressure , fault (geology) , geotechnical engineering , geophysics , physics , quantum mechanics , thermodynamics
Seismological observations highlighted that earthquakes are often followed by changes in elastic properties around the fault zone. Here, we studied the origin of these variations using stick‐slip experiments on saw‐cut granite samples presenting different degrees of bulk damage (i.e., microcracks). Stick‐slip events were induced under triaxial compression configuration with continuous active ultrasonic measurements at confining pressures representative of upper crustal conditions (15–120 MPa). Both the P‐wave velocity ( V P ) and amplitude ( A P ) showed drops, concurrently with stress drops, and had a non‐monotonic dependence toward the fault's stress state. Our experimental results suggest that co‐seismic changes inV Pwere mostly controlled by the elastic re‐opening of microcracks in the bulk, rather than by co‐seismic damage or the formation of fault gouge. Co‐seismic changes inA Pwere controlled by a combination of elastic re‐opening of microcracks in the bulk and inelastic processes (i.e., co‐seismic damage and gouge formation and dilation).