Surface Deformation in Imperial Valley, Southern California, from Satellite Radar Interferometry

This project aimed at detecting, measuring, and analyzing the surface deformation or land elevation changes in the Imperial Valley of Southern California, using satellite radar data for the periods February 2003 through October 2010 and August 2012 through October 2013. InSAR data were used to detect land elevation changes, making it possible to cover large areas at once, with spatial density compared with ground-based methods.  

The main reasons for surface displacements in the study area are tectonic movements and anthropogenic activities in geothermal fields, both with potential impact on the extensive agricultural activities in the area. The state-of-the-art InSAR technique used here, SqueeSAR, provided deformation time series at thousands of individual points, including in the agricultural areas where earlier InSAR techniques failed. The purpose of the project was to establish a deformation baseline in current and prospective geothermal fields, as well as around active faults. 

The results show similar subsidence patterns from two satellites. The project also detected displacements associated with right strike-slip movements on faults. The results also show abrupt movements from an aseismic event in October 2006 and a M7.2 April 2010 earthquake that occurred south of the U.S. – Mexico border.  

The project demonstrates the viability of the applied technique for surface deformation monitoring. Continuing this monitoring in the future is recommended, especially with the technological advancements with more precise satellite instruments. At sites of interest, for which deformation time series cannot be currently obtained, the installation of corner reflectors is recommended to assure targeted monitoring with future satellite data. 

A follow-up project took place during 2017 through 2020. Before these two projects, an initial study which took place between 2003-2007. These projects build upon each other underscoring the potential and benefits of using satellite radar data to monitor deformation in California known geothermal resource areas over time.