SALT LAKE CITY – Researchers at the University of Utah say an unusual series of earthquakes that occurred in central Utah in 2018 and 2019 are a reminder of the ancient volcanoes of Utah in the area. Fortunately, they say there is no indication of an impending eruption.
The research, first published in Geophysical Research Letters last month, centered around some bizarre earthquake series in the Black Rock Desert near Fillmore. One of the central earthquakes in Utah occurred on September 12, 2018, and the other on April 14, 2019. The earthquakes registered as 4.0 and 4.1, respectively, and produced several aftershocks.
The location of both earthquakes was the volcanic field of the Black Rock Desert located in central Utah between I-15 and the state line of Utah-Nevada. The volcanic area last erupted about 720 years ago, which according to the Ice Geological Survey led to basal cones and flows through Ice Springs.
In addition to the earthquakes detected by the Utah Regional Seismic Network, they were captured 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, 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 quake was 1½ miles below the surface, which is fairly shallow for earthquakes. The 5.7 magnitude earthquake that struck the Wasatch Front last year, for example, occurred about 6 kilometers below the earth’s surface; the central earthquakes in Utah in 2018 and 2019 were not related to the earthquake in Magna, the largest in Utah since 1992.
In addition, the quakes did not produce ‘shear waves’, which is common for earthquakes in Utah. The frequency of the seismic energy was also much lower than the typical earthquakes in Utah, Maria Mesimeri, a fellow postdoctoral research fellow at Seismograph Stations of the University of Utah and lead author of the study, said in a news release on Tuesday.
“Because these earthquakes were so shallow, we were able to measure surface deformation (due to the earthquakes) using satellites, which is very unusual for earthquakes of this small nature,” she said.
The data led researchers to believe that the earthquakes were not caused by collisions like most earthquakes in Utah; rather, they said their research suggests that these earthquakes were the result of ongoing activities in the volcanic field beneath the desert.
Mesimeri said that both earthquakes could probably be caused by magma or heated water that came closer to the surface and caused the 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 environment,” she said. “The earthquakes may be due to the fluid pushing through rock or due to deformation due to fluid motion emphasizing the defects in the surface.”
The good news, she added, is that there is no reason to believe that the recent earthquakes are warning signs of an impending eruption. It just means that it is a place that researchers want to pay more attention to.