It may not look like that, but the arid expanses of Utah hide an ancient volcanic complex, and this hidden underground system is still active far below the surface of the desert, scientists say.
According to a new study, a pair of recent earthquakes in 2018 and 2019 did not indicate tectonic activity, but were seismic noises produced by the volcanic field in the Black Rock Desert – an ancient volcanic system in the Sevier Desert in Utah, active over 6 million years and apparently is still alive.
“Our findings suggest that the system is still active and that the earthquakes were probably the result of liquid-related movement in the general area,” said seismologist Maria Mesimeri of the University of Utah.
“Earthquakes could be the result of fluid squeezing through the rock or the result of deformation from the movement of the fluid that highlighted surface defects.”
The two earthquake sequences in question took place in September 2018 and April 2019 and were recorded by seismometers in the Utah regional seismic network, as well as instruments that are part of an experimental project called Utah FORGE, led by the Department of Energy in the USA.
Subsequent analysis of the waveforms in the episodes showed that these earthquakes were not the result of tectonic activity, with surface signals coming from depths less than 2.5 kilometers (1.5 miles) below the surface.
“The seismic signals from these earthquakes were unusual and uncharacteristic of tectonic earthquakes and we rule out the possibility of a collapse or explosion of a mine,” explains Mesimeri and her co-authors in their study.
“We confirm that the two earthquakes are superficial and find a distinct surface deformation.”
Evidence suggests that unlike other earthquakes in the area that come from fault movements and tend to produce more seismic energy, the superficial events of 2018 and 2019 were caused by the transport of volcanic fluids in the Black Rock volcanic field, regardless of whether it is heated water. or rocky. magma.
Despite the ancient age of the volcanic complex, its quietness in terms of obvious volcanic activity means that it is a relatively little-known feature of the great landscape of Utah. The last eruptive event of Black Rock took place over 1,000 years ago, resulting in lava flows in the Ice Springs region.
As to whether the latest noises are indicative of future outbreaks, there is no evidence to that effect, the researchers say. But these earthquakes remind us that Black Rock is still active after all these years and that this latent volcano has not disappeared.
“The results showed us that we should pay more attention to the Black Rock area,” says Mesimeri.
“We need to improve seismic and volcanic monitoring in this area so that we are aware of the small changes that may occur.”
The findings are reported in Geophysical research letters.