Time-series analysis of surface deformation associated with fluid extraction at Cerro Pabellón Geothermal Power Plant in Chile

Abstract:

Cerro Pabellón, the first geothermal power plant in South America (Central Volcanic Zone CVZ of the northern Chilean Andes) is a high enthalpy binary cycle plant with 48MW (plus 33MW approved) that operates at high altitude (~4500 m). Geothermal fluid extracted from the production wells is fully injected back into the reservoir. However, because the power plant began operation in 2017 it is not yet known if there is any surface deformation associated with these activities or some other tectonic influence.

Here we analyze interferometric synthetic aperture radar (InSAR) time series data with 130 SAR scenes from the Sentinel-1A/B satellites spanning between 2014 and 2020 to measure and characterize the anthropogenic deformation at the Cerro Pabellón geothermal plant. Preliminary results show line-of-sight subsidence up to 1.5 cm during 2017-2019, showing deformation began immediately after the geothermal production started in 2017. We present source models of the ground deformation and compare it with geologic and geophysical observations including groundwater levels from well data, magnetotelluric imaging, and microseismicity.
InSAR time series and the model results will help to better understand the fluid flow beneath the plant and the potential impact of the geothermal plant on the surface as well as the faults that bound the graben where the geothermal plant is.