Remote Surveillance Trailer in Dayton, NV

The United States Geological Survey put out a false alarm for a 5.9 earthquake east of Dayton, Nevada, on Thursday morning.

"This was an errant earthquake warning sent out by the USGS’s ShakeAlert system," Kyren Bogolub, seismologist at the University of Nevada, Reno Seismological Laboratory, told the RGJ. "There was no earthquake. We are awaiting more information from the USGS. Thank you for your patience while we sort this out."

At the Roadrunner Café in Dayton, a regular customer said he heard there was a 5.9 earthquake on the radio, but that came as a surprise to Shannon Mackey.

Mackey is the manager at the family-run breakfast spot. It was breakfast as usual, she said when asked by the Reno Gazette Journal.

“Oh sweetheart, I didn't feel anything if there was one,” Mackey said.

Dayton is in Lyon County just east of Nevada's capitol of Carson City.

Lyon County sent a notice confirming residents "received a false alert of a 5.9 earthquake at 8:06am near Dayton. We are awaiting additional information and will share when it is available. There is currently no hazard to the public. We are asking the public to not call 911.

The alert also went out to residents in Washoe County and as far as the Bay Area in California.

Real earthquakes that have struck in Nevada

While Thursday's report of a 5.9 was a false alarm, Nevada has seen some major quakes. It's the third most seismically active state in the U.S. behind California and Alaska, according to the National Parks Service.

The state is striped with fault lines, and more than two dozen earthquakes of 6.0 and above have struck Nevada in records dating back to 1860.

Here's a look back at the highest-magnitude earthquakes in Nevada history, according to the U.S. Geological Survey's database.

10 largest earthquakes in Nevada history

7.1 — Fairview Peak earthquake, Dec. 16, 1954: The first of two major earthquakes that struck near Fallon just four minutes and 20 seconds apart. It was the largest of a series of quakes that shook the area beginning in summer.

6.9 — Dixie Valley earthquake, Dec. 16, 1954: The aftershocks of the two Dec. 16 earthquakes were so extensive, they were still being recorded in 1963.

6.8 — Pleasant Valley earthquake, Oct. 3, 1915: The earthquake in rural southeastern Pershing County prompted an investigation into whether downtown Reno's Majestic Theater, about 100 miles away from the epicenter, was safe for occupancy.

6.8 — Cedar Mountain earthquake, Dec. 21, 1932: The earthquake was felt strongly in Reno, cracking building foundations, breaking hundreds of windows and causing power outages in Fallon, Fernley and Lovelock.

6.5 — Carson City earthquake, June 3, 1887: Residents of northwestern Nevada were shaken from sleep just before 3 a.m., cracking foundations in the capital; the Reno Evening Gazette reported the quake produced a "low rumbling noise" like distant thunder.

6.5 — Stillwater earthquake, Aug. 24, 1954: This earthquake was a forerunner of much larger quakes in December and possibly the most destructive of the year. Buildings, roads and dams in the Fallon area were severely damaged.

6.5 — Post Canyon earthquake, March 15, 1860: Centered about 1 ½ miles southwest of the present-day Switch campus at the Tahoe-Reno Industrial Center, this quake startled residents of Carson City and Virginia City.

6.5 — Monte Cristo Range earthquake, May 15, 2020: A May 15 earthquake, magnitude 6.5, was the largest earthquake to hit Nevada since the 1954 quakes. Several sections of US 95 were damaged, but no other significant damage was reported.

6.4 — Virginia City earthquake, Dec. 27, 1869: The Gold Hill Daily News said the earthquake and aftershocks were "to the infinite disgust of nearly everybody who desired sleep and rest" and wondered "when this foolishness is going to stop."

6.4 — Reno earthquake, April 24, 1914: The largest of a series of earthquakes that lasted from February through April.

More significant earthquakes in Nevada history

Magnitude, approximate location, date

6.3 — Excelsior Mountains, Jan. 30, 1934

6.3 — California-Nevada state line east of Truckee, Sept. 3, 1857

6.2 — Rainbow Mountain, July 6, 1954

6.2 — Carson City, Dec. 27, 1869

6.1 — Carter Springs, Sept. 12, 1994

6.08 — Stagecoach, June 25, 1933

6 — Humboldt, Oct. 3, 1915

6 — Reno, Feb. 18, 1914

6 — Austin, Nov. 12, 1872

6 — Virginia City, May 30, 1868

5.9 — Wells, Feb. 21, 2008

5.9 — Winnemucca, Feb. 3, 1916

5.9 — Fallon, July 6, 1954

5.88 — Incline Village, April 24, 1914

5.8 — Yerington, Dec. 9, 2024

5.8 — Lovelock, Aug. 31, 1954

5.8 — Gabbs, Dec. 16, 1954

5.8 — Owyhee, Aug. 3, 1916

5.8 — Beatty, June 29, 1992

5.71 — Fallon, March 23, 1959

5.7 — Fallon, July 6, 1954

5.7 — Rachel, Feb. 28, 1975

5.7 — Rachel, Dec. 20, 1975

5.7 — Goldfield, Aug. 1, 1999

5.65 — Caliente, Aug. 16, 1966

5.63 — Excelsior Mountains, Jan. 30, 1934

5.6 — Owyhee, Aug. 3, 1916

5.6 — Hawthorne, Dec. 28, 2016 (12:18 a.m.)

5.6 — Hawthorne, Dec. 28, 2016 (12:22 a.m.)

5.6 — Dyer, July 21, 1982

On Thursday morning, many people across Northern California and Nevada saw earthquake alerts, warning of a magnitude 5.9 quake near Dayton, Nevada.

The words “Drop! Cover! Hold on!” flashed on phones, warning people to brace for major tremors, only for nothing to happen — no shaking, no earthquake at all.

The warning came from ShakeAlert, the earthquake early-warning system run by the U.S. Geological Survey at the Department of the Interior. The system, which operates in California, Oregon and Washington, is designed to provide advanced notice about earthquakes so people can turn off machinery or get to safe locations before shaking begins.

Within minutes of the alert, officials realized there had been no earthquake, pulled the alert and confirmed on social media it had been a false alarm.

“The earthquake alerts that were delivered at 8:06am are cancelled,” USGS posted on Facebook and other major social platforms shortly after the false warnings were sent. “There was no M5.9 earthquake near Carson City, NV. We are currently looking into why the alerts were issued.”

Robert de Groot, who heads the Shake Alert operations team at USGS, said the automatic detection system detected ground motion and triggered the false alert, but confirmed within minutes that an earthquake had not occurred. He said Shake Alert uses four sensors, rather than one, to mitigate false alerts. In this instance, all four sensors went off.

“The important thing is the shaker Earthquake Early Warning System performed as it was designed in terms of the sensor network, which actually detects the earthquake and the ground motion, de Groot said. “The system was just reacting to the data that that looked and smelled like an earthquake. Something was detected at those sensors.”

The USGS tracks false earthquake alerts on its website, which states that the “faster we release earthquake locations and magnitudes, the more likely it is that the information may be erroneous.” The department lists two false alerts since ShakeAlert’s 2019 launch, both issued in California in 2020. One alert detected seismic activity 200 kilometers away from the where the sensor was located and was unlikely to result in an earthquake. The other was triggered by a 7.5 magnitude earthquake in Russia, which confused the earthquake monitoring system in Northern California.

De Groot said that while Shake Alert has issued more than 170 successful alerts, Thursday’s miscommunication is unlike the others in that it’s the first time the system has issued a false alert using data that was not collected from an actual earthquake that took place. The team is still investigating the source of the trigger.

“Earthquake early warning is done over a very short time period, we’re talking matters of seconds,” de Groot said. “So if you put your hand on your heart couple of heartbeats, that time of two heartbeats or so, about a second, that is all we need to get things moving in the Shake Alert system.”

A 5.9 magnitude earthquake near Dayton, Nevada, was a “bogus event,” according to the United States Geological Survey.

Millions of residents from Nevada to California received an alert informing them of an earthquake just after 8 a.m. PT.

But USGS quickly realized something was awry and deleted information about the quake from its website, puzzling onlookers.

The agency said later Thursday that its automatic earthquake detection system erroneously sent the report, though it’s not clear why.

A spokesperson for the USGS said there was no such temblor in the region, about 12 miles northeast of the state capital Carson City, saying the report was "a bogus event."

The USGS was trying to understand what went wrong and why the automatic earthquake detection system sent out the alert, the spokesperson said.

Multiple law enforcement agencies in surrounding cities and counties also confirmed that they did not feel any shaking or other signs of an earthquake.

A magnitude 5.9 quake typically is strong enough to cause slight property damage and strong shaking, according to the Michigan Tech Earthquake Magnitude Scale.

DAYTON, Nev — Confusion spread across Northern California on Thursday after thousands of residents received earthquake alerts warning them to “drop, cover and hold on.”

But officials now confirm no earthquake occurred, and the notification was the result of a false ShakeAlert activation.

The Nevada Seismological Laboratory, the state agency responsible for seismic monitoring, confirmed the error Thursday.

“It was a false alert from the ShakeAlert system,” officials said. “Our system in Nevada did not detect an earthquake.”

Despite early reports of a magnitude 5.9 quake near Dayton, Nevada, the state’s seismic network shows no earthquake activity in the area at the time the alerts were sent.

Officials noted that Nevada does not yet operate ShakeAlert, the West Coast early-warning system responsible for sending earthquake notifications to phones.

That system is run through the University of California, Berkeley, and the U.S. Geological Survey. The Berkeley Seismology lab said they haven't had a false alert like this where there was no real earthquake.

The USGS Shake Alert posted on X confirming there was no 5.9 earthquake near Carson City, NV. "We are currently looking into why the alerts were issued," they wrote.

.@USGS #ShakeAlert confirms that the earthquake alerts that were delivered at 8:06am are cancelled. There was no M5.9 earthquake near Carson City, NV. We are currently looking into why the alerts were issued. We'll provide more information when we learn more @Cal_OES @CAGeoSurvey

— USGS ShakeAlert (@USGS_ShakeAlert) December 4, 2025

Residents across the Sacramento region reported receiving the alert even though no shaking occurred. Emergency managers emphasize that false alarms, while rare, can happen when automated systems misinterpret signals or receive faulty triggers.

Further information from UC Berkeley and USGS is expected as they review how the false alert was issued.

DAYTON, Nev. - The U.S. Geological Survey sent out an erroneous alert on Thursday, stating originally that an earthquake with a magnitude of 5.9 struck in Nevada, but then pulled that alert back, saying it was a mistake.

According to the initial alert, the quake struck just after 8 a.m. east of Dayton, Nevada.

USGS alert deleted

Timeline:

Then, moments later, the USGS deleted the event from its website.

In a post on X, the USGS said there was no 5.9 earthquake in Nevada and that they canceled the faulty alert.

"We are currently looking into why the alerts were issued," the USGS posted. "We'll provide more information when we learn more."

Several people also reported getting earthquake alerts on their phones. One person wrote on social media that the MyShake app woke her up, and then she looked again, and it wasn't listed.

A spokeswoman for the Nevada County Sheriff's Office told KTVU via email that they have no affiliation with the earthquake alert.

"We didn’t feel anything here but we are quite a ways from Dayton," the spokeswoman wrote.

Dayton is 40 miles from Reno.

Why was the false earthquake alert triggered?

What experts say:

The Shake Alert seismology team said they are now working to review the data, but that it appears the faulty alert might've been caused by a software error.

"The Shake Alert system is fully automated," Jeff McGuire, USGS Shake Alert chief scientist, said. "It's listening to data all the time, and there [were] some anomalies in the data from Nevada that caused us to or caused the system to interpret it as an earthquake."

He said the system's sensors detected what it thought might be an incoming wave.

"A number of sensors detected what they thought was an incoming seismic wave," he said. "Some on the Nevada side of the border and some on the California side of the border. And that information was combined to make the alert."

The USGS quickly posted a correction.

"There are humans assigned to be on watch 24/7, and they, when the alert went out, they checked the data and determined that this was a false alert, and that led it to be removed from the web pages and things like that, which is standard operating procedure," McGuire said.

McGuire says the system requires data from a minimum of four sensors placed at intervals of about 20 kilometers in order to trigger an alert.

Now, scientists are reviewing the data and the algorithms to determine if the mistake was from the software failing to filter out a false trigger that can sometimes occur.

"Many things can cause the ground to shake. Construction, big trucks — most sensors are located in places that are relatively free from that kind of noise, but there's still any number of things that show up on our data all the time," he said.

McGuire says it will likely take days to finish analyzing the data to get a better idea of what went wrong.

They are also expecting an update from phone companies to determine how many people received the false alert.