SALT LAKE CITY – Researchers from the University of Utah say an unusual sequence of earthquakes that occurred in central Utah in 2018 and 2019 is a reminder of Utah’s ancient volcanoes in the area are active. Fortunately, they say there is no indication of an impending outbreak.
The research, first published in Geophysical Research Letters last month, centered around a few quaint earthquake sequences in the Black Rock Desert near Fillmore. One of the central earthquakes in Utah occurred on September 12, 2018, and the other occurred on April 14, 2019. The quakes were recorded as 4.0 and 4.1 in magnitude, respectively, and produced several aftershocks.
The location of both earthquakes was the Black Rock Desert volcanic field, located in central Utah between I-1
In addition to being detected by the Utah Regional Seismic Network, the earthquakes were caught by temporary seismic equipment used less than 20 miles from the desert to monitor a geothermal well for another project.
A team of researchers from the University of Utah, the USGS and the University of Iowa went to work analyzing the data. The temporary equipment helped detect 35 aftershocks after the 2019 earthquake, which was almost double what the normal system detected.
They found that the earthquake was 1½ miles below the surface, which is quite low for earthquakes. For example, the 5.7 magnitude earthquake that struck the Wasatch Front last year happened about 6 miles below the earth’s surface; the central earthquakes in Utah in 2018 and 2019 were independent of the Magna earthquake, Utah’s largest since 1992.
In addition, the earthquakes did not produce “displacement waves,” which is common to earthquakes in Utah. The frequency of the seismic energy was also much lower than the typical Utah earthquakes, Maria Mesimeri, a postdoctoral research assistant for the University of Utah Seismograph Stations and the study’s lead author, said in a press release Tuesday.
“Because these earthquakes were so low, we were able to measure surface formation (due to the earthquakes) using satellites, which is very unusual for such small earthquakes,” she said.
The data led researchers to believe that the quakes were not caused by colliding faults like most Utah earthquakes; rather, they said their research showed that these earthquakes were the result of ongoing activity in the volcanic field below the desert.
Mesimeri said it is likely that both earthquakes may have been caused by either magma or heated water that came closer to the surface and caused earthquakes.
“Our findings suggest that the system is still active and that the earthquakes were likely the result of fluid-related movement in the general area,” she said. “The earthquakes may be the result of the liquid squeezing through rocks, or the result of deformation from fluid movement that underlined the surface defects.”
The good news, she added, is that there is no reason to believe the recent earthquakes are warning signs of an impending eruption. It just means that it is a place that researchers might want to pay more attention to.
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