The ominous tweet from the @Quakeprediction account, published at 7:39 p.m. Tuesday, read: "15 HOUR WARNING: 6.7 to 7.2 earthquake is likely in the Los Angeles area - late on 09/28/2021 or 09/29/2021 - (most likely NW of Los Angeles)."
The Twitter account, which has about 45,700 followers, is connected to the website quakeprediction.com, which claims: "We have been researching earthquake prediction since 2005," adding, "We are not associated with the USGS earthquake prediction site."
The Tuesday evening tweet went on to receive more than 600 "likes" and nearly 400 retweets. According to Google Trends, searches increased for such terms such as "quake prediction" and "earthquake prediction Los Angeles."
Of course, Wednesday came and went without a major quake striking the region.
"If you're asking if a quake prediction is legit: Look at the predictor's account," Dr. Lucy Jones, one of the most esteemed earthquake experts in the U.S., tweeted Wednesday afternoon. "How many times have they posted a prediction? (Must be before the quake - postdictions don't count.) How many times did a quake actually happen?
"I haven't seen a legit one yet."
If you're asking if a quake prediction is legit: Look at the predictor's account. How many times have they posted a prediction? (Must be before the quake - postdictions don't count.) How many times did a quake actually happen? I haven't seen a legit one yet.— Dr. Lucy Jones (@DrLucyJones) September 29, 2021
Jones went on to define "postdiction" as "claiming a successful prediction after the quake occurs."
"One guy sent a fax predicting a big quake in LA in the next week to a different company each week. The company that got it just before Northridge hit was impressed," she recalled, referring to the magnitude 6.7 earthquake that struck the San Fernando Valley in 1994.
Jones also shared this bemusing anecdote:
"The 1986 North Palm Springs M5.9 was the first big quake after I moved to California," she tweeted. "I watched a more senior scientist, Tom Heaton, talk to the press 2 hours after the quake. When a reporter asked if the quake had been predicted, Tom calmly replied 'Not yet.' Best answer ever."