Areas shown in blue on this map are subsiding, with darker blue areas sinking faster than lighter blue ones. The areas shown in dark red are rising the fastest. The map was created by comparing thousands of scenes of synthetic aperture radar (SAR) data collected between 2007 and 2011 and 2014 and 2018.

Mapping Ground Subsidence

Mark Altaweel

Synthetic Aperture Radar (SAR) can map subtle differences in the rates of subsidence.

NASA's UAVSAR measured cumulative vertical ground movement impacting the California Aqueduct near Huron and Kettleman City from July 2013 to March 2015. The colored overlay shows areas where subsidence exceeded 7 inches (17.8 centimeters). UAVSAR pixel resolution is 20 by 20 feet (6 by 6 meters). Credits: NASA/JPL-Caltech

California is Sinking Faster than Previously Thought

Elizabeth Borneman

Researchers are tracking the changes in California’s geography from the effects of drought using a remote sensing system called interferometric synthetic aperture radar, or InSAR.