TY  - JOUR
A1  - Martínez-Garzón, Patricia
A1  - Kwiatek, Grzegorz
A1  - Bohnhoff, Marco
A1  - Dresen, Georg
T1  - Volumetric components in the earthquake source related to fluid injection and stress state
JF  - Geophysical research letters
N2  - 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 (M-w 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 (M-w<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 M-w>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.
KW  - non-double-couple components
KW  - induced seismicity
KW  - geothermal
KW  - stress state
KW  - tensile opening
KW  - pore pressure
Y1  - 2017
U6  - https://doi.org/10.1002/2016GL071963
SN  - 0094-8276
SN  - 1944-8007
VL  - 44
IS  - 2
SP  - 800
EP  - 809
PB  - American Geophysical Union
CY  - Washington
ER  -