© US Geological Survey/Amanda SweeneyA view of Lassen Peak in California from the south of the summit of Brokeoff Volcano in Lassen Volcanic National Park.
In a recent study, researchers used multiple sets of data from an Interferometric Synthetic Aperture Radar (InSAR) to look at the more than 10,000-foot high volcano located in the Shasta Cascade region of Northern California and track characteristics of deformation in the peak's vicinity between 1992 and 2010. They discovered that there was a broad range of sinking measuring about 18 to 24 miles and progressing at the rate of about a centimeter per year.
InSAR uses radar images of earth's surface to track changes on the ground, according to the U.S. Geological Survey. Unlike visible or infrared light, radar waves are able to see through clouds and are equally effective in the dark, allowing researchers to see changes at night and during bouts of bad weather, which comes in handy during a volcanic crisis. The images collected by the radar are compared to each other to determine if there was any movement of the ground surface.
The scientists' research lead them to believe that this slow sinkage of Lassen Peak has been going on since the 1980s. They believe the source of the sinking is a point located about 5 miles beneath the volcano's center.
"Time-series analysis suggests that the rate of volume change of this source may have varied over time," the researchers wrote. "The source geometry and the temporal evolution of deformation contrasts to subsidence observed at nearby Medicine Lake Volcano since the 1950s."
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