An earthquake swarm continues to quietly rumble below Sun Valley north of Reno, at one point producing more than 60 temblors in a span of just a few hours.

The swarm, which started in the early morning hours of Wednesday, June 19, has so far only produced small quakes, not strong enough to be felt by humans on the surface.

It's impossible to predict if the swarm will produce anything strong enough to rattle a person or home — some swarms increase in intensity and some peter out without ever being felt — but the burst of activity has drawn the attention of scientists at the University of Nevada Reno's Nevada Seismological Lab, who keep watch over the Silver State's movings and shakings.

"Anytime there are a lot of earthquakes in one place it's something we pay attention to because it means there is strain being released, even if it's only recorded instrumentally," said Annie Kell, a seismologist with the UNR lab.

'We could have some very, very large earthquakes'

Nevada is the third-most seismically active state in the country behind Alaska and California, though the state hasn't had a seriously destructive quake in quite some time.

That lapse isn't necessarily viewed as a good thing. It means that Nevada, a state whose population has exploded in recent decades, is filled with people who are likely oblivious to the seismic forces at work beneath their feet — and, perhaps more importantly, the serious danger those forces pose.

"In reality, we could have some very, very large earthquakes (in Nevada)," Kell said.

There are occasional reminders of that danger, including a 2008 magnitude 6 earthquake in the eastern Nevada town of Wells that shook the facades off historic buildings and a swarm in Mogul that same year that cracked walls in homes.

Earlier this month, a magnitude 3.7 epicentered in Washoe Valley was felt across the Truckee Meadows, with over 1,300 people reporting feeling the temblor to the U.S. Geological Survey.

A devastating earthquake 'can happen — it will happen'

That quake, which hit just before 10 p.m. on Thursday, June 6, is likely to have originated from the Mt. Rose Fault Zone, an extensive "mountain building" system of faults that poses the largest threat to the Truckee Meadows, according to Kell.

"That's the fault we're most concerned about producing a life-threatening rupture," she said. "Anytime there's an event that probably happened on the Mt. Rose Fault System, we start to pay pretty close attention."

The Mt. Rose Zone is a latticework of folds and cracks in the earth's crust stretching from Washoe Valley, underneath the Arrowcreek area and on through the heart of Reno.

At its worst, it's thought to be capable of producing a 6.5 magnitude earthquake, which could devastate the region, Kell said.

Last year, an earthquake swarm near Galena High School in South Reno produced hundreds of small events and lasted about a week.

The current swarm in Sun Valley has slowed, Kell said, with the most recent event detected early Thursday morning. At its peak in the early-morning hours of June 19, the swarm produced about 60 quakes in a matter of hours.

Nevertheless, UNR's Nevada Seismological Lab has placed temporary instruments in the area to better keep track of the quakes.

There's no telling when a major earthquake will hit the region, but Kell said residents can do minor things — like strapping down water heaters and creating plans with your family — to be better prepared.

"In general, always be prepared for an earthquake," Kell said. "It can happen — it will happen — and at some point there is going to be a devastating magnitude earthquake in the Reno area."

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Sam Gross is a breaking news reporter for the Reno Gazette Journal who covers wildfires, emergencies and more. Support his work by subscribing to RGJ.com right here.