An algorithmic error told Californians they’d be in for a major earthquake on Wednesday, but the earthquake had already happened ― in 1925. 
 
 The automatically generated report from the U.S. Geological Survey indicated that a magnitude 6.8 quake would occur in the Pacific Ocean 10 miles west of Santa Barbara. 
 
 Alerts were sent for a M6.8 in California. This was an error. More information to come. — USGS (@USGS) June 22, 2017 
 
 As a frame of reference, a magnitude 6.9 earthquake in 1989 killed 63 people and caused $6 billion of damage in California. 
 
 So what gives with this quake scare? 
 
 “The quake did happen, but it happened in 1925,” Rafael Abreu, a geophysicist with the U.S. Geological Survey, told The Associated Press. 
 
 This should seem like good news, but the false alarm still sent shockwaves through social media. Many automated tweets, synced with the USGS alert system, were pushed out, sparking concern. 
 
 Additionally, people around the country began to scratch their heads as no one had reported feeling tremors ― something that most certainly would have happened in large numbers had an earthquake of that size actually come about. 
 
 @DrLucyJones M6.8 90 miles away Im sure we'd feel it right? Is this real? pic.twitter.com/OX1MzcgFrC — Alex S (@alxxdes) June 22, 2017 
 
 Still, publications like the Los Angeles Times, which has automated emails from the USGS to aid in its coverage, ended up alerting the public about the fake quake and then had to rescind the messages. 
 
 Please note: We just deleted an automated tweet saying there was a 6.8 earthquake in Isla Vista. That earthquake happened in 1925. — L.A. Times: L.A. Now (@LANow) June 22, 2017 
 
 We have an algorithm (Quakebot) that automatically writes stories about earthquakes based on USGS alerts. The USGS alert was incorrect. — L.A. Times: L.A. Now (@LANow) June 22, 2017 
 
 The LA Times bot even generated an article about the fake quake: 
 
 Was the article automated too? pic.twitter.com/C8lMJa2dM9 — Colin Cooley (@runwicked) June 22, 2017 
 
 Yes: Quakebot is an algorithm that automatically writes stories based on USGS alerts. — L.A. Times: L.A. Now (@LANow) June 22, 2017 
 
 So, how did the USGS casually send out an alert that confused even the LA Times? 
 
 Apparently false alarms are fairly common, though the AP says “they rarely report quakes so big or in such populated areas.” 
 
 Also, researchers from the California Institute of Technology were using new information to analyze the epicenter of the 1925 earthquake in the Santa Barbara Channel. That earthquake ― a real one ― leveled several buildings and killed many people. You can see the LA Times’ article from that quake below: 
 
 False alarm: Caltech staffer accidentally sends alert for large 1925 Santa Barbara earthquake https://t.co/zSyy4Yzmvt pic.twitter.com/oNXJRUwZFN — Los Angeles Times (@latimes) June 22, 2017 
 
 Even more intriguingly, the full quake report associated with Wednesday’s tweet listed the date as June 29, the same date as the 1925 quake, but indicated it would happen in the year 2025. So, yeah, that USGS report was all sorts of screwed up. 

 Remember Y2K, that hyped computer bug and harbinger of digital apocalypse that never happened when the year 2000 arrived? 
 
 Well, 17 years later, it appears something like a Y2K bug played a role in a mistaken alert sent out Wednesday about a magnitude 6.8 earthquake off the Santa Barbara coast — back in 1925. 
 
 The error happened when someone at Caltech tried to correct the exact location recorded for the Prohibition-era Santa Barbara earthquake, which happened 92 years ago. 
 
 From the Archives — June 1925: Earthquake devastates Santa Barbara » 
 
 The erroneous report was issued around 4:49 p.m., according to the U.S. Geological Survey, and began arriving in quake-trackers’ email in-boxes around 4:51 p.m. A closer look at the alert, however, would have shown that something was amiss. The time of the alert was dated June 29, 2025, at 7:42 a.m. But it corresponds with a real earthquake that occurred a century earlier. 
 
 The false alert also did not show up on the USGS website that maps new earthquakes. 
 
 “That’s a mistake. It’s not real,” said Caltech seismologist Egill Hauksson. 
 
 He said that a seismologist at UC Santa Barbara had recently complained to the USGS National Earthquake Information Center that the precise location of Santa Barbara’s 1925 earthquake was not correct and about 6 miles off from where records actually indicated. 
 
 Hauksson’s team was asked by the National Earthquake Information Center to update the location of the historic event in the Advanced National Seismic System database. Someone on Hauksson’s team did so. If everything had gone right, almost no one should have noticed the change. 
 
 The USGS Web pages were updated correctly. But in the USGS email notification system, the year got changed from 1925 to 2025, which caused an email to be sent from the server that typically distributes alerts of new earthquakes. 
 
 “Apparently, there is a software bug around somewhere,” a summary of the incident provided by Hauksson said. 
 
 The bug was related to something called “ Unix epoch time,” which starts in 1970, Hauksson said in an email. “The year of 1925 wrapped around in the software and became 2025,” he said . 
 
 In a statement posted on Twitter, the USGS said the revision of the 1925 earthquake was “misinterpreted by software as a current event. We are working to resolve the issue.” 
 
 As to whether an earthquake off the Santa Barbara coast of that magnitude would have been felt in downtown L.A., Hauksson said: “Yes, it would have been very lightly felt. Particularly, people in high-rises would have felt swaying back and forth for a while.” 
 
 If the quake had just occurred, the L.A. area would have felt the shaking before the USGS alert arrived in local email boxes, Hauksson said. For instance, Pasadena, which is about 96 miles from the origin of the 1925 Santa Barbara earthquake, would be expected to feel shaking about 40 seconds after the earthquake would have begun in the Santa Barbara Channel — fast enough to outpace the existing USGS email alert system. 
 
 The expected intensity in Pasadena for a magnitude 6.8 quake that originated 96 miles away would be a 3.3 on the Modified Mercalli Intensity scale. 
 
 Here is what intensity 3 and intensity 4 quakes feel like, according to the USGS: 
 
 Intensity 3: “Felt quite noticeably by persons indoors, especially on upper floors of buildings. Many people do not recognize it as an earthquake. Standing motor cars may rock slightly. Vibrations similar to the passing of a truck.” 
 
 Intensity 4: “Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.” 
 
 https://twitter.com/USGS/status/877685556003692545 
 
 https://twitter.com/alxxdes/status/877677727301554176 
 
 A 6.8 earthquake hit Santa Barbara in June 1925. This is what the disaster looked like » 
 
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 UPDATES: 
 
 11:55 a.m.: This article was updated with additional details about the software bug and how, if there had been a quake, the Los Angeles area would have felt shaking before the the USGS notifications arrived in email boxes. 
 
 10:10 a.m., June 22: This article was updated with more information about the origin of the error, involving USGS email notification. 
 
 7:35 p.m.: This article was updated with information on what showed up on the USGS website. 
 
 5:55 p.m.: This article was updated with a statement from the USGS. 
 
 4:55 p.m.: This article was updated with information that the report was erroneous. 
 
 This article was originally published at 4:52 p.m. June 21.
– On Wednesday afternoon California residents were shocked to learn that a powerful earthquake had supposedly hit the Pacific Ocean about 10 miles off the coast of Santa Barbara. They were probably just as surprised to learn a few minutes later that the magnitude 6.8 quake had actually happened in 1925. The Los Angeles Times reports that a staffer at the California Institute of Technology mistakenly triggered an alert while correcting information about the location of the 92-year-old quake for the US Geological Survey's earthquake database. An email was then sent out from the USGS email server claiming that the 1925 quake was set to occur on June 29, 2025. The Washington Post reports that email alert automatically generated a story on the Times site through an algorithm called Quakebot. The HuffPost reports that several automated tweets synced to the USGS server were sent out as well, causing confusion. USGS corrected the mistake on Twitter shortly after the initial alert went out and followed up with a more detailed explanation on its website within a half hour. The Times sent out tweets explaining the mistake and blaming the original USGS alert. The paper also tweeted a picture of its front-page coverage of the 1925 Santa Barbara earthquake, which, it reported at the time, “demolished or seriously damaged virtually all brick concrete and stone structures in the city,” "virtually wrecked" a famous hotel, and forced the city's 30,000 residents to evacuate their homes and sleep outside.