Two earthquakes struck Nevada within seconds of one another on Friday in a region where the Earth’s crust is gradually pulling apart.
The US Geological Survey (USGS) recorded the tremors at magnitudes 3.6 and 3.5 near Preston, a community with more than 160,000 residents.
According to an assessment by Michigan Technological University, earthquakes measuring between 2.5 and 5.4 are often felt but typically cause only minor damage.
No damage was reported following Friday’s seismic activity.
The stronger earthquake occurred at 10:10am ET, followed by the second tremor just 24 seconds later outside Preston. The town lies within the Basin and Range Province, a vast area extending across much of the western United States.
In the province, the Earth’s crust is slowly stretching and thinning, creating numerous faults and making earthquakes relatively common.
As the crust separates, fractures called faults develop. Earthquakes occur when sections of the Earth’s crust move along those faults.
Although Friday’s earthquakes were relatively weak, seismic activity across the Basin and Range Province reflects the continuing process that is splitting, stretching and reshaping the region.
A magnitude 6.5 earthquake struck Nevada in 2020 (pictured), likely as a result of cracking and stretching across the Basin and Range Province
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The Basin and Range Province covers more than 300,000 square miles, including large parts of Nevada, Utah, eastern California, southern Idaho and Oregon, Arizona and New Mexico.
As the crust stretches across the province, it fractures into enormous blocks.
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Some blocks drop downward to create valleys, while others stay elevated or tilt to form mountain ranges.
Over millions of years, this stretching has broadened the region and reduced the thickness of the crust beneath it.
Friday’s tremors came after a series of earthquakes near Preston in recent months, including two magnitude 4.1 earthquakes recorded west of the community on September 27.
The USGS ShakeMap indicated that the strongest shaking was concentrated near Friday’s epicenter and weakened with increasing distance from the source.
Trina Thomasson wrote on Facebook that she felt the shaking in Ely, about 32 miles northeast of Preston.
Nevada is the third-most seismically active state in the US, behind Alaska and California, according to the Nevada Bureau of Mines and Geology.
Earthquakes occur somewhere in the state every day.
Nevada has also experienced earthquakes strong enough to permanently alter the landscape.
On December 16, 1954, a magnitude 7.1 earthquake struck Fairview Peak in central Nevada. About four minutes later, another major earthquake hit nearby Dixie Valley.
The two events shifted the ground along several faults, producing vertical movement of about 12 feet in some locations.
They also caused landslides and rockfalls and altered the flow of springs and wells.
However, a sequence of smaller earthquakes does not necessarily mean that a major earthquake is imminent.
The USGS notes that some earthquake clusters end without a larger event. Scientists can only identify a tremor as a foreshock after a bigger earthquake has occurred.
