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Aseismic Deformation in and Around the North Brawley Geothermal Field

Session: Effects and Uses of Aseismic Deformation and Fault Creep in Seismic Hazard and Warning

Type: Oral

Date: 4/20/2021

Presentation Time: 06:30 PM Pacific

Description: 

The North Brawley Geothermal Field, located within the Brawley Seismic Zone of Southern California, presents a case study for understanding the impacts of active geothermal energy production on seismic hazard. The geothermal field has been associated with both induced seismicity and aseismic ground deformation in the past decade. In particular, an earthquake swarm in 2012 resulted in two M5+ earthquakes and was likely preceded by an aseismic slip transient. To better understand this ground deformation, including its evolution with time and its causative mechanisms, we construct a comprehensive deformation time series using multiple ground- and satellite-based geodetic techniques between 2009 and 2019. We integrate observations from GNSS, Sentinel-1, TerraSAR-X, UAVSAR, and leveling surveys into a single deformation history. We then test whether models of aseismic slip and/or poroelastic deformation can explain this time history. We find evidence for both aseismic fault slip and poroelastic deformation during the last decade, including some episodes not previously identified or quantified. We also identify geodetic transients that may indicate very shallow interseismic creep on nearby strike-slip faults of the San Andreas fault system. In the geothermal field, we compare the deformation history with injection and production parameters and seismicity catalogs over the past decade. This long-term deformation history allows us to probe the geothermal field’s response to both long-term and short-term temporal changes in operational parameters, which has implications for other geothermal operations around the world.

Presenting Author: Kathryn Materna

Student Presenter: No

Authors