The world’s largest earthquake drill will take place on Thursday, with millions set to practice what to do if a massive quake hits — a scenario experts say could likely happen in Southern California in the next several decades.
The “Great Shakeout,” an annual earthquake drill that started in Southern California in 2008, will happen on Oct. 19 at 10:19 a.m. local time around the world. Nearly 20 million people will practice what to do if a quake strikes, with more than 10.2 million of them in just California.
“I think we’ve seen with recent disasters in the past couple of months — these big hurricanes and the Mexico earthquakes in September, and the wildfires that are still happening in California — the need to be prepared is so important,” said Jason Ballmann, a spokesman for the Southern California Earthquake Center.
The center collaborated with the United States Geological Survey (USGS) and other partners to create the earthquake drill based on a magnitude 7.8 scenario earthquake on the San Andreas fault in Southern California.
Drills around the world will take place in schools, colleges, federal and local agencies, and private businesses and will be at least a minute long. But the Southern California Earthquake Center encourages them to be longer.
“We know that in the shakeout scenario with a 7.8 earthquake, up to four minutes of shaking could be felt,” Ballmann said.
Earthquake drills happen all year-round, but the Great Shakeout is the biggest one. In Mexico, which suffered three devastating and deadly earthquakes last month, buildings in Mexico City had held earthquake drills just hours before the Sept. 19 quake hit.
Related: After Mexico Quake, California Urges Residents to Prepare for ‘The Big One’
“A drill at 11 a.m. and an earthquake at 1 p.m.,” Valerie Perez, 23, a student, said at the time. “This is the most powerful thing I have ever seen in my life.”
An earthquake of a very large magnitude is also not out of the question for the Bay Area in Northern California, where multiple massive fault lines lie, say experts.
“The Bay Area sits right in the boundary zone between the Pacific plate and the North American plate. They’re sliding past each other at about 40 millimeters a year, a little less than 2 inches,” said David Schwartz, a geologist with the USGS. “Doesn’t sound like a lot, but over the years, that builds up to a lot of stress and motion.”
A 2014 study led by the USGS found that by the year 2043, the probability of Southern California experiencing one or more magnitude-6.7 or larger earthquakes was 72 percent.
“That’s a pretty high number,” Schwartz said. “The biggest concern is the Hayward fault because it sits geographically in the center of the Bay Area. It’s the most densely populated. There are 2 million people directly on top of it. When it has an earthquake, it will affect the 8 million people or so living in the greater Bay Area.”
Related: Mexico Earthquake: More Than 200 Dead as Buildings Collapse
The area has seen its share of significant temblors in the past, including the Great 1906 San Francisco earthquake along the San Andreas fault, a 7.8-magnitude earthquake that killed more than 7,500. In 1868, a quake estimated to be between 6.3 and 6.7 rocked the Hayward fault, nearly obliterating buildings and infrastructure in what was at the time a sparsely populated Bay Area.
The Great Shakeout teaches participants to “drop, cover, and hold on” — meaning get on the ground, cover your head with one arm, and hold onto a stable object like a desk or sturdy table, if one is nearby.
Research has shown that staying stationary is almost always safer than running, even if it goes against your natural inclination to flee, said Lori Dengler, an emeritus professor of geology at Humboldt State University in Northern California.
“What we’re really trying to do with Shakeout is instill a new instinct, which is to drop down. And once you’ve dropped down, wherever you are, you can’t run. So that anchors you in one place and then if you can, slide under a desk or a table, that’s great,” she said.
Dengler said she encourages anyone experiencing an earthquake to count while the shaking is happening.
“Counting does two really important things in an earthquake. First, it actually helps calm you down,” she said. “The second reason, if you live on the coast in a tsunami zone, the length of an earthquake is your indication of how large the magnitude is … Once you get over a count of about 30 [seconds], that’s Mother Nature telling you that this earthquake could be big enough to produce a tsunami.”
She pointed out that not just California is susceptible to earthquakes.
“There’s not a single part of the United States that can’t have an earthquake,” she said. “We’re all at risk. The real important thing about Shakeout is developing the muscle memory to do the right thing when the ground is shaking, and the right thing is to basically not move.”