%A Patricia Martinez-Garzon
%A Grzegorz Kwiatek
%A Marco Bohnhoff
%A Georg Dresen
%J Geophysical Research Letters
%T Volumetric components in the earthquake source related to fluid injection and stress state
%X We investigate source processes of fluid-induced seismicity from The Geysers geothermal reservoir in California to determine their relation with hydraulic operations and improve the corresponding seismic hazard estimates. Analysis of 869 well-constrained full moment tensors (Mw 0.8–3.5) reveals significant non-double-couple components (>25%) for about 65% of the events. Volumetric deformation is governed by cumulative injection rates with larger non-double-couple components observed near the wells and during high injection periods. Source mechanisms are magnitude dependent and vary significantly between faulting regimes. Normal faulting events (Mw < 2) reveal substantial volumetric components indicating dilatancy in contrast to strike-slip events that have a dominant double-couple source. Volumetric components indicating closure of cracks in the source region are mostly found for reverse faulting events with Mw > 2.5. Our results imply that source processes and magnitudes of fluid-induced seismic events are strongly affected by the hydraulic operations, the reservoir stress state, and the faulting regime.
%N 2
%P 800-809
%V 44
%D 2017
%I American Geophysical Union
%R doi:10.1002/2016GL071963
%L epos1930