It may not look like it, but the arid expanse of Utah hides an ancient volcanic complex, and this hidden underground system is still active far below the desert surface, scientists say.
According to a new study, a few recent earthquakes in 2018 and 2019 were not an indication of tectonic activity, but were seismic rumblings generated by the Black Rock Desert volcanic field – an ancient volcanic system in Utah’s Sevier desert which is already more than 6 million active. years and is apparently still alive and kicking.
“Our findings suggest that the system is still active and that the earthquakes were likely the result of fluid-related motion in the general environment,” said seismologist Maria Mesimeri of the University of Utah.
“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 two earthquake series in question occurred in September 2018 and April 2019 and were recorded by seismometers in the Utah Regional Seismic Network, as well as by instruments part of an experimental project called Utah FORGE, managed by the U.S. Department of Energy.
Subsequent analysis of the waveforms from the episodes showed that these earthquakes were not the result of tectonic activity, with shallow signals emanating from depths of less than 2.5 kilometers (1.5 miles) below the surface.
“Seismic signals from these earthquakes were unusual and uncharacteristic of tectonic earthquakes, and we rule out the possibility of a mine collapse or explosion,” Mesimeri and her co-authors explain in their study.
“We confirm that the two earthquakes are shallow and that the surface can be deformed.”
The evidence suggests that, unlike other earthquakes in the area that stem from fault motions and tend to produce more seismic energy, the shallow 2018 and 2019 events were produced by the transport of volcanic fluids within the volcanic field of the Black Rock, whether heated water or rocky magma.
Despite the ancient centuries of the volcanic complex, the silence in terms of distinct volcanic activity means that it is a relatively rare feature of the vast Utah landscape. Black Rock’s last eruption event was more than 1,000 years ago, leading to the region’s Ice Springs lava flows.
On the question of whether the most recent noise is an indication of future eruptions, there is no evidence for it, the researchers say. But these earthquakes are a reminder that Black Rock is still active after all these years, and that this dormant volcano has not become extinct.
“The results showed us that we need to pay more attention to the Black Rock area,” Mesimeri says.
“We need to improve seismic and volcanic monitoring in this area so that we are aware of small changes that may occur.”
The findings are presented in Geophysical research letters.