There were two earthquakes early Wednesday morning with magnitudes over 5.0 that rumbled under the Pacific Ocean off the Northern California coast.

The first of the quakes, with a magnitude of 5.7 on the Richter Scale, struck at 3:53 am about 95 miles due west of the California-Oregon border. The USGS puts the epicenter at 154 kilometers WSW of Pistol River, Oregon.

The second earthquake, 5.1M, occurred at 5:45 am and its epicenter was further south, off the coast of Eureka. Its epicenter was about 40 miles off the coast, or 64 kilometers west of Petrolia, California, in Humboldt County.

This earthquake's depth was relatively shallow, just about a half-mile below the seafloor.

There was subsequently a 4.5M aftershock in the same area at 6:11 am.

Some shaking was likely felt in and around Humboldt County from the latter two quakes, but no damages have been reported. At least one or two people on Xitter in Humboldt County reported the shaking.

This area off the NorCal coast is known to be highly tectonically active, and the latter two earthquakes occurred near what's called a triple-junction, where the northern end of the San Andreas Fault intersects with the Mendocino Fracture Zone  and the Cascadia Subduction Zone. The earlier, larger quake appears to have occurred along the Cascadia Subduction Zone.

The most recent earthquakes off the San Francisco coast occurred on April 25, and had magnitudes of 3.0 and 2.7.

• The San Francisco Giants hired Gary Pettis, who’s Oakland born and raised, as the team’s third base coach. Pettis has 27 years of coaching experience, including with the Chicago White Sox, the New York Mets, and the Houston Astros when they won the World Series in 2017 and 2022. [ESPN]
• Parth Patel, 30, and Dharti Patel, 29, from San Mateo, drowned at the site of a waterfall in Fresno last week when Dharti slipped on a rock and Parth jumped in to save her. [NBC Bay Area]
• A minor, 3.7-magnitude earthquake struck about 4 miles southeast of Cloverdale Tuesday morning at 9:44 am, along with subsequent quakes. [New York Times]

National:

• The U.S. military says it carried out “self-defense” strikes on Iranian targets, including Qeshm Island and an oil tanker near the Strait of Hormuz, while also shooting down Iranian missiles and drones amid escalating crossfire in the Gulf region. [BBC]
• President Donald Trump signed an executive order creating a voluntary framework for AI companies to share and allow up to 30-day federal review of advanced models for national security risks before public release, following earlier hesitation over concerns about hindering U.S. competitiveness. [Associated Press]
• The Supreme Court is allowing Alabama to use a Republican-drawn congressional map that eliminates a court-ordered second majority-Black district, reversing lower court rulings that found the map likely violated the Voting Rights Act and had been drawn with discriminatory intent. [NBC News]

Video of the Day:

• It's hard to tell whether this was staged or not, but either way, this particular Waymo came away with some battle scars. As for the unflappable passenger and canine inside, we can only hope they were allowed to continue on their way soon after, or whatever.

View on Threads

Image: Leanne Maxwell/SFist

A sizable early morning earthquake centered near Silver Springs, Nevada was felt strongly in Reno and Lake Tahoe, as well as parts of Northern California.

The 5.2M quake struck at 1:17 am Friday in western Nevada, about 40 miles east-southeast of Reno — 12 miles southeast of Silver Springs.

According to the US Geological Survey, the quake had a depth of around 3 miles, and was followed by five smaller aftershocks.

There were subsequent earthquakes centered in the same vicinity near Silver Springs measuring between magnitude 2.5 and 2.7, occurring at 1:22 am, 1:23 am, 3:32 am, 3:35 am, and 4:48 am.

Shaking from the initial quake could be felt as far west as Sacramento, according the USGS Shakemap.

As the Chronicle notes, this part of western Nevada has been experiencing an earhquake swarm that has included several quakes of significant size and hundreds of smaller ones in recent weeks.

A 5.7M quake struck the area on April 13, and there was also a 4.8M quake on April 22.

Photo via Wikimedia

For the second time in four months, a false-alarm alert about an earthquake was triggered in Northern California, and this was actually multiple alerts, but this time there thankfully were no loud alarms on cellphones rattling Bay Area residents awake.

The US Geological Survey has some questions to answer about a series of false alerts that were somehow triggered on its automated earthquake detection system Monday night in multiple locations. As the Chronicle reports, these included two off-shore earthquakes west of the Bay Area, as well as locations near Bonny Doon in Santa Cruz County, near Point Reyes, near Yreka, and near Shaver Lake in Fresno County.

The false alerts were for quakes ranging in size from 3.2M to 3.8M.

The Sacramento Bee, for instance, has this report, via the CA Earthquake Bot, showing an earthquake with a preliminary magnitude of 3.7 having struck offshore, 53 miles west-southwest of Bonny Doon, at 8:48 pm. If you look at the USGS earthquake site today, however, no such quake appears, and the only Bay Area quake in the last 24 hours was a 2.8M that struck just after midnight near San Ramon — the site of an ongoing earthquake swarm that began last fall.

As the Chronicle notes, the USGS's automated earthquake detection system can "occasionally produce erroneous readings due to signal interference or processing errors," but these instances are reportedly supposed to be "rare."

In early December, Bay Area residents were alarmed by an 8:06 am "Critical" earthquake warning about a 5.9M quake, pushed out to cellphones that subscribe to the ShakeAlert system with a blaring alarm sound, however the warning seemed immediately suspect because of the location of the false quake — which was centered in Lyon County, Nevada.

Even an earthquake of that size likely would not have been felt over 200 miles away in the Bay Area.

The USGS quickly retracted the report and issued an apology on X, saying "There was no M5.9 earthquake," and "We are currently looking into why the alerts were issued."

The incident prompted a rebuke from California politicians the following week, with Representative Kevin Mullin and four other Democratic House members writing to the USGS and saying, "The public relies on USGS for authoritative, real-time information during earthquakes," and this public trust is "essential." Governor Gavin Newsom also said that the error put a spotlight on the Trump administration's cuts to federal agencies like the USGS.

Per the New York Times, Christie Rowe, director of the Nevada Seismological Laboratory at the University of Nevada, Reno, put out a statement suggesting that "a faulty power system" at one of the seismic monitoring stations in Nevada was likely to blame for the false alarm.

The malfunction at that one station reportedly caused data transmission issues throughout the ShakeAlert system.

And this system is gaining a reputation for unfortunate glitches that can lead to widespread, if brief, panic. You'll recall that after the system went online, there was an earthquake drill scheduled for 10:19 am on October 19, 2023, but the loud alert instead went out seven hours early, at 3:19 am, to cellphones around the Bay Area.

The USGS blamed that one on a time-zone mix-up.

Previously: That 5.9M Earthquake Warning Out of Nevada Was Fake News

It hasn't been felt very much in San Francisco, but the earthquake swarm that has been rocking San Ramon for the past three months had its most active day on Monday, with a barrage of 75 small and mid-size earthquakes. And residents in the area are pretty on edge.

Monday's earthquake swarm centered near the East Bay city of San Ramon was not the first to hit the area in recent weeks and months, but it was probably the most sustained, after a few other earthquakes hit there on Friday.

SFist initially reported on the series of earthquakes around 8 am, at which point 17 earthquakes had struck with magnitudes measuring between 2.0 and 4.2. The swarm continued throughout the day, with some of the quakes around 1.0M being less noticeable, ultimately totaling 75.

The most recent of the quakes, which continued into Tuesday, was a 2.5M temblor that struck at 1:45 pm today. There was also a 2.8M quake recorded at 9 am today, according to the US Geological Survey.

As one area resident, Sue Wild, tells the Chronicle today, the first quake to hit Monday morning, a 3.8M that struck at 6:27 am, was no joke if you were in the immediate vicinity. "It literally felt like a freight train was coming through the middle of the bed."

Area residents admit that they're pretty rattled at this point, nerves on edge, etc., anticipating that all these mini-quakes are leading up to a Big One in the near future, where more than just a few trinkets may fall off some shelves.

"Obviously, mentally it’s kind of taxing and you are always thinking about, ‘Is this the big one?'" says 45-year-old recent San Ramon transplant Lynn Tao, speaking to the Chronicle, after relocating there in 2024.

The Chronicle asks the question of whether San Ramon has now become the most seismically active area in the world, but experts say that's actually hard to pin down. Over time, for instance, The Geysers, the area in northern Sonoma County and Lake County that is home to geothermic springs, geysers, power plants, and thus seismic shaking, is extremely active, though many of the quakes there are just little 1.0M jiggles.

And, as Angie Lux, a seismologist at Berkeley Seismology Lab, tells the paper, there are regions all over the world with either no seismic sensing technology or very few nearby residents — Alaska being an example where plenty of shaking is probably going on in places where very few people exist nearby.

But San Ramon certainly takes the cakes in terms of significant swarms that we know about in the last few months. The latest seismic activity, which the area is not unfamiliar with, began in mid-November with a swarm of 83 quakes spread over 10 days. Seimologists noted there have been five such swarms, some lasting more than a month, recorded in the San Ramon area since 1970.

Experts don't have a definitive answer for why this area is so seismically active, but one theory suggests that these swarms are triggered by fluid moving between subfaults in the Calaveras Fault zone.

Previously: Another Series of San Ramon Earthquakes Rumbles Under East Bay

The lead author of a recent study about how major earthquakes in the Pacific Northwest have been historically linked to seismic events in California, specifically on the San Andreas Fault, says he sees some upside to the findings, at least for those of us in California.

Those among us who pay close attention to new earthquake science likely heard about the study that came out this fall that found evidence of the historical "partial synchronization" of the Cascadia subduction zone in the Pacific Northwest and the San Andreas Fault. The study's authors looked at the geological record of major seismic events on the Cascadia subduction zone and on the San Andreas, and found that major quakes on the northern San Andreas Fault were likely directly triggered by larger events in the Cascadia, occurring minutes, hours, or even days or months after.

Specifically, the 9.0+-magnitude event that occurred in the Pacific Northwest in the year 1700 — which was covered in a widely read 2015 New Yorker piece — triggered a similarly large quake on the northern San Andreas that occurred within 20 minutes to one year after the Cascadia event. Sedimentary evidence from beneath the sea floor confirms the two events were closely linked, the study says.

Now, the study's lead author, Bay Area native Chris Goldfinger, has sat down with the Chronicle to discuss his main takeaways from his years studying both fault zones. And he concludes that there is a silver lining in the findings, particularly for those living near the San Andreas Fault.

"If Cascadia went off, it would serve as a warning system to the Bay Area," Goldfinger tells the paper. He adds, "When you have one fault rupture, it transfers stress to nearby faults, in this case the northern part of the San Andreas fault. The issue is if there were a quake on the Cascadia, you wouldn’t know if San Andreas would go off in 10 minutes or 10 years — even as much as 50 years. But chances are it would be sooner than later."

Goldfinger notes that even a couple minutes warning would help save lives, with things like the BART system being able to keep trains out of tunnels, and bridges potentially able to be cleared of traffic.

He even suggests, and he doesn't seem to be joking, that if there were a major seismic disaster in the Cascadia subduction zone, it might be "a good time for a vacation in Tahoe." In other words: Head for the hills.

This early warning from a disastrous quake up north is cold comfort to residents of Seattle and Portland, but for those in Northern California, Goldfinger says, "I’m starting to see this as more of a positive than a problem."

Still, he says, such a double earthquake event would be devastating, both in terms of loss of life and economic impacts for the entire West Coast.

"Either one alone would be a national event, but my concern is the ability to respond to either event would be diminished because we would run out of resources," Goldfinger says, adding that airports and seaports would likely see major damage from Seattle potentially down to Los Angeles.

Now, we've been told for years that the next Big One in the Bay Area is more likely to occur on the Hayward Fault, because it is more "due" for a big event — the last big earthquake on that fault was in 1868, and such quakes appear to happen with about a 150-year frequency, you do the math. And a 2019 study suggested that a 7.0M quake on the Hayward Fault, centered under Oakland, would likely result in around 800 deaths and could leave around 52,000 homes on fire.

Meanwhile, the Cascadia zone, which is a convergent fault zone involving multiple tectonic plates sliding under the North American plate extending from Vancouver Island to Cape Mendocino, has a 37% chance of producing a 7.0M or greater quake in the next 50 years.

Also, the San Andreas Fault has a habit of producing "extra" events that aren't linked to the Cascadia fault at all. Goldfinger says that the catastrophic 1906 earthquake was just one of those.

Let this be yet another reminder to get your go-bags and household earthquake plans together!

Related: Hayward Fault Earthquake Scenario Imagines 52,000 Homes On Fire, 800 Deaths

Top image: Photo by ekrem osmanoglu

Millions of Northern California residents received a Shake Alert warning at 8:06 am Thursday about an earthquake with an epicenter in Lyon County, Nevada, but the quake itself soon disappeared from the USGS website, and the agency said it was a false alarm.

An alarming "Drop, cover, hold on" message popped onto the phones of Bay Area residents this morning with the MyShake app or other warning system, warning of imminent shaking from a large earthquake in Nevada, centered near Dayton — which is 29 miles south of Reno, and about 12 miles east of Carson City. But now it looks like that was all just a false alarm.

The US Geological Survey posted to Xitter at 8:45 am apologizing for the alert, saying, "There was no M5.9 earthquake near Carson City, NV. We are currently looking into why the alerts were issued."

Subsequently, the USGS-managed Shake Alert system posted a message saying the incident was being investigated, and added, "This system has delivered more than 170 real alerts since 2019 and this incident is both unprecedented and rare."

Was the USGS hacked? Did somebody's truck drive over an earthquake sensor in the desert?

We may know more soon. Angie Lux, a scientist at the Berkeley Seismological Laboratory, which manages the MyShake app, tells the Chronicle, "It’s gonna take a little bit of time to understand exactly what happened with the system, but we can say that there was no earthquake and that we’re looking into what happened."

And maybe this is just me, but it also seems like the MyShake messaging was kind of extreme for an earthquake that happened hundreds of miles away, which was likely only to cause minor shaking in the Bay Area, if any at all?

This is a developing story and has been updated.

A small but noticeable 3.6-magnitude earthquake happened Thursday at 12:41 pm, with an epicenter two miles southeast of Vallejo.

According to the US Geological Survey, a 3.6M earthquake rumbled just south of Vallejo Thursday afternoon, and miled shaking was felt in San Francisco, the East Bay, and parts of the North Bay.

The earthquake appears to have occurred along the Southampton Fault, which appears like a northern extension of the Calaveras Fault — a fault running under the East Bay and down to Hollister, just east of the Hayward Fault.

A swarm of small earthquakes along the Calaveras Fault occurred on Sunday morning, as the Chronicle reported, with the largest being 3.8M. The fault is thought to be capable of producing quakes as big as 6.7M, or thereabouts.

A map below shows the major and minor faults under the Bay Area, with the Southampton Fault appearing in yellow, labeled with the number 11. It crosses paths with the Franklin Fault, which leads directly out of the Calaveras Fault and under the city of Vallejo.

Connected faults are believed to be able to erupt together, potentially causing larger earthquakes. A study from almost a decade ago found that the Rodgers Creek and Hayward faults are interconnected, capable of causing a quake along a stretch that extends 115 total miles.

• The East Bay city of San Ramon was the center of at least seven small earthquakes Sunday morning, starting with two back-to-back 3.8 and 3.7 magnitude earthquakes at 9:38 am, followed by two 3.0 and 2.9 quakes. [NBC Bay Area]

• The Trump administration is demanding that the states that began administering SNAP payments Friday give the money back after Supreme Court Justice Ketanji Brown Jackson paused an earlier ruling by a federal judge calling for the immediate disbursement of payments. [The Associated Press]
• Thirteen infants in ten states have been hospitalized with botulism linked to baby formula sold under the Whole Nutrition Infant Formula brand from two lots: 206VABP/251261P2 and 206VABP/251131P2; no deaths have been reported. [Bay Area News Group]
• The folks at Marine Mammal Center recently reunited a sea otter pup named Caterpillar with her mom after the pup became stranded on the beach at Morro Bay, as seen in this heartwarming video. [Marine Mammal Center]

Image: Leanne Maxwell/SFist

• Over 10,000 Air Canada flight attendants went on strike early Saturday, prompting the Canadian government to force the airline into arbitration. The shutdown of the airline, which operates about 700 flights a day, has left over 100,000 travelers stranded worldwide. [Associated Press]

• Mayor Lurie claimed his office secured $3.4 million in immigrant legal defense funding, which was actually awarded to the public defender’s office. Additionally, he neglected to renew $878,000 in grant funding that London Breed was awarded last year. [Mission Local]
• The Golden State Valkyries won their fourth game in a row Friday, scoring 90-59 against the Chicago Sky. [Bay Area News Group]
• The second bird in a month has been found to be infected with the West Nile virus — a crow from Walnut Creek tested positive on Friday. [KRON4]

• There have been 117 tiny earthquakes since Thursday’s 4.0-magnitude quake near the Geysers geothermal field in Mendicino, northeast of Healdsburg. [SFGate]

Image: Leanne Maxwell/SFist

Top image: California's Old Faithful Geyser, in Calistoga, via Visit Calistoga/Facebook

Is something happening on the Hayward Fault? We can't say if these are precursors to something bigger or just your average minor earthquake swarm. But the Hayward Fault has been moving today.

Residents of the East Bay, particularly in and around Hayward, have felt a series of small jolts today, beginning with a 2.7M quake that happened at 5:03 am. That was followed by slightly larger quakes — a 3.3M quake at 11:52 am, a 3.2M quake two minutes later, and then a 3.6M quake at 1:59 pm which was felt across the Bay in San Francisco.

That latter earthquake had an initial magnitude of 3.7M.

We are overdue, as you may have heard, for a major earthquake on the Hayward Fault. The last so-called 150-year event on the fault happened in 1868, and you can do the math there.

The US Geological Survey launched an earthquake preparedness project in 2019 called HayWired. It imagined a scenario in which a 7.0M quake comes to the Hayward Fault, and they estimate that could cause 800 deaths, upwards of 100,000 people could be displaced, and interruptions of water service could cause small fires to become conflagrations like what happened in the 1906 earthquake — burning, potentially, 52,000 homes.

Sadly, if such a thing happens during this Trump administration, we could end up being more on our own than ever before in terms of disaster response and FEMA help.

And, sadly, when "#earthquake" trends on Twitter as it did today, with these Hayward earthquakes, there are a bunch of jackasses who turn this political and show their glee about California experiencing such a disaster. One such poster today said every time he sees the hashtag trending "I hope California has finally became part of the Pacific Ocean and my property in Nevada is now ocean front. Someday."

Anyway, we'll use this opportunity to remind you to get a go-bag together in the event of a major earthquake — here's a guide to pulling one together. And you should also have ample bottled water, canned goods, and cash in small bills on hand in the event that you need to shelter in place without power or water.

There was just an earthquake in the Bay Area Saturday morning, a small 3.4M tremor that was centered on the Hayward Fault just south of the UC Berkeley campus.

The quake occurred at 11:12 am, according to the US Geological Survey, and was at a depth of 9.4 km.

The shaking could be felt, if only mildly, in San Francisco. And the tweets do reflect that.

The last earthquake we felt here on February 2, which was of the same magnitude, was on the San Andreas Fault and was centered under the ocean off the coast.

Didja feel it? A 3.4-magnitude earthquake shook San Francisco just after 1:30 p.m. Friday afternoon, and fortunately, no damage is being reported.

Yes indeed that was a small earthquake you may have felt at approximately 1:32 pm Friday afternoon. That sent many San Franciscans scrambling to Twitter to see if other people felt it too, and to the Twitter account SF QuakeBot to size up the magnitude of the tremor.

The initial report from  Quakebot says it was a 3.4 magnitude earthquake, though that’s just a preliminary assessment that may be updated.

According to an SF Fire Department tweet from 2 p.m., "We have not seen or received calls for any damage related to this recent earthquake preliminary reported off the coastline of #SF," and "The @NWSBayArea confirmed NO coastal surge issues are expected."

While the earthquake struck off the coast, about three miles west of the SF Zoo, there are reports the quake was felt as far away as Berkeley and Oakland. Though many in San Francisco say they didn't feel anything.

This quake came just hours after a slightly larger one, 4.9M, likely also on the San Andreas Fault, occurred further north below the Pacific, about 70 miles southwest of Eureka.

And this is a great reminder to make sure you’ve prepared a “go bag,” or earthquake preparedness kit, for if and when a bigger quake does indeed strike.

Related: Golden Gate Bridge Finally Getting Long-Overdue Earthquake Seismic Retrofit [SFist]

Image: @LastQuake via Twitter

New geological research indicates that the West Napa Fault, which caused the destructive and deadly 2014 Napa quake, may be nine miles longer and potentially much deadlier than previously thought.

This past August marked the nine-year anniversary of the 2014 Napa earthquake, which killed one person, injured 208 more, and did at least $400 million in damages to that NorCal region. That 6.0 magnitude quake was the largest the Bay Area has seen since the 1989 Loma Prieta earthquake, but we’re now learning it could have been much worse. That’s because, as the Chronicle reports, geologists have discovered that the West Napa Fault that caused the earthquake is likely nine miles longer than they’d realized.

The West Napa Fault had generally been considered to be about 35 miles in length, stretching from south of the city of Napa northward to St. Helena. New research from United States Geological Survey geologist Belle Philibosian indicates the fault actually stretches nine miles further north to just past Calistoga. That means that a rupture on the fault could potentially cause a 7.0 magnitude earthquake, which would be a bigger tremor than Loma Prieta.

“The northward extension was a little bit of a surprise,” Philibosian told the Chronicle. “We didn’t necessarily anticipate that there was an additional section of fault.”

Philibosian’s research is not yet published, so the findings could be updated with forthcoming additional academic review. But the Chron also spoke with other geologists, and there is an emerging consensus among them that the West Napa Fault probably does extend further north than they'd realized.

So let this serve as a reminder, particularly if you’re in Napa or Solano County, to get your earthquake “go bag” ready for if and when a natural disaster strikes. It’s a lazy holiday week, and a perfect time to take on easily overlooked projects and errands.

Related: 6.0 Earthquake Hits Near Napa, 120 Injured [SFist]

Image: Cullen328 via Wikimedia Commons