Earthquakes in the Black Rock Desert are rare and capturing the seismic recordings from these earthquakes provides a glimpse into the volcanic system of the Black Rock Desert that, while not showing any signs of erupting, is still active.

A pair of earthquake sequences, in September 2018 and April 2019, focused scientists’ attention on the Black Rock Desert. The sequences, which included the main quakes and their aftershocks, were very different from the Magna earthquake that shook the Wasatch Front in 2020 and other Utah earthquakes. The Black Rock sequences were captured by the Utah Regional Seismic Network and by nearby temporary seismic equipment deployment that was monitoring a geothermal well. Earthquakes in the Black Rock Desert are rare and capturing the seismic recordings from these earthquakes provides a glimpse into the volcanic system of the Black Rock Desert that, while not showing any signs of erupting, is still active. A study of the earthquake sequences is published in Geophysical Research Letters.

«The results showed us that we should give more attention to the Black Rock area,» says Maria Mesimeri, a postdoctoral research associate with the University of Utah Seismograph Stations. «We need to improve seismic and volcanic monitoring in this area, so that we are aware of small changes that may occur.»

Not your typical earthquakes

The earthquake sequences, with main shocks of magnitude 4.0 and 4.1 respectively, were picked up by both the Utah Regional Seismic Network and a dense temporary network of seismometers deployed as part of Utah FORGE, an experimental geothermal project funded by the U.S. Department of Energy and operated by the University of Utah, located about 19 miles south of the Black Rock Desert near Milford, Utah. The temporary network allowed researchers to detect more aftershocks than usual. For example, the regional network detected 19 earthquakes as part of the April 2019 sequence. But the dense temporary network detected an additional 35 quakes. Each additional aftershock provided a bit more information for seismologists studying the sequence.

The Black Rock sequences showed some interesting features that set them apart from the 2020 Magna sequence and other Utah earthquake sequences. While the initial Magna quake occurred at a depth of about six miles below the surface, a typical depth for Utah earthquakes, the Black Rock quakes were much shallower — around 1.5 miles below the surface.

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Materials provided by University of Utah. Original written by Paul Gabrielsen. Note: Content may be edited for style and length.