Year: 2026
Type: article
Abstract: The long-term producing Coso Geothermal Field (CGF) in California operates over 100 wells tapping into a reservoir characterized by an extensive fracture network, complex fluid pathways, and regular seismic activity. Understanding the interaction between seismicity and injection can shed important light on the hydrothermal characteristics of the field. Here, we analyze 15 years of local seismic and daily operational data from the CGF, identifying a strong correlation between short-term increase in seismicity rate and seasonal volumetric and temperature variations in the reinjected fluid. Furthermore, the seismic footprint during peak injection of colder fluids reveals a near-instantaneous response up to 2 km away from the injection well, too rapid for pore pressure diffusion alone. This short-term and distant response is observed to have directional preference, indicating structural or permeability anisotropy within the reservoir. Additionally, the seismic response correlates with the initial volumetric increase of colder fluids, but also with temperature decrease during stable injection periods, suggesting thermal effects alone can play an important role in triggering distant seismicity.
Source: Scientific Reports
Authors: Joanna M. Holmgren, J. Ole Kaven, Volker Oye
Institutions: Norsar, United States Geological Survey, Earthquake Science Center
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,690
Funders: Universitetet i Bergen, U.S. Navy
OpenAlex ID: W7127308116