Not Just for S.F. & L.A.: All Californians Should ShakeOut on Oct. 21

The annual Great California ShakeOut is October 21. If you were one of the 6.5 million Californians to participate in 2020, gold star! This is an opportunity to practice the drop, cover, and hold on drill.

Drop, Cover, Hold On!

Join us for ShakeOut, a drill that doesn’t cost anything, is relatively easy to do for most people, and could save your life.

California is Earthquake Country

You may have heard this before: California is earthquake country.

One of the Department of Conservation’s foundational pillars is hazards management, and the California Geological Survey (CGS) has numerous earthquake-related programs and products.

Thousands of earthquakes occur in the state weekly, most too small to be felt. The mid-sized ones — the magnitude 4.0s to 5.5s — can knock stuff off shelves and at the higher end can damage older buildings. Temblors of this size occur several times each year.

Photo of DOC scientist with a ruler measuring the lateral displacement of surface rupture of the roadway caused by the Ridgecrest earthquake
CGS scientist taking lateral displacement measurements of surface rupture.

The quakes that measure magnitude 6.5 or greater, capable of causing regional devastation at the high end, are perhaps once or twice a year occurrences.

Don’t Live Near a Fault Line? Shaking May Still Reach You

There are well-known earthquake hotspots in California: Greater Los Angeles and the Inland Empire, the San Francisco Bay Area, the North Coast.

The “earthquake capital of the world” is a little town called Parkfield in a remote corner of Monterey County.

Other parts of California – the Central Coast, eastern California (from the Mojave Desert up along the eastern Sierra Nevada and through Lake Tahoe region), and Wine Country — occasionally get quakes capable of doing real damage.

CGS scientist checking how much the ground moved after an earthquake.

Central Valley cities such as Sacramento, Stockton, and Modesto generally are seismically quiet. But the reality is that a city doesn’t have to sit atop a fault line to experience quake impacts. If an earthquake is close enough and large enough, the shaking may be felt, and damage can occur, even in the Central Valley.

Reasons Why Earthquakes Can Have Widespread Effects

The structure in which you live and the soil upon which it’s built will be a factor. Larger earthquakes shake longer.

That is why a really big one generated offshore of the North Coast (the Cascadia Subduction Zone) could be a concern for Sacramento. The shaking might not feel very strong in the capital, but the duration could cause damage to older buildings, levees to fail, and the ground west of the capitol building — areas that were built up with fill dirt in the late 1800s because of flooding — to fail.

The magnitude 6.9 Loma Prieta Earthquake, which disrupted baseball’s World Series on October 17, 1989, was centered outside of Santa Cruz on the San Andreas Fault. It caused death and destruction about 65 miles away in the greater Bay Area.

Highway collapse in San Francisco after the Loma Prieta earthquake in 1989.

It also was felt strongly in certain parts of Sacramento built on loosely compacted soil, roughly 115 miles away as the crow flies. Had it been even a bit bigger, there could have been significant damage and injuries in a community where hardly anyone gives earthquakes a second thought.

In 1868, the Hayward Fault produced what was estimated to be a magnitude 7.0. It was known as the “Great San Francisco earthquake” until a much larger one came along in 1906. The Hayward Fault is only about 50 miles from Stockton and 60 miles from both Modesto and Sacramento.

Destruction and fire in San Francisco after the 1906 quake.

Rely on Scientists for Data, Not Hollywood

If most of your information about big earthquakes comes from movies, you may misunderstand what the hazard actually is. Buildings and structures such as bridges and freeway overpasses certainly have failed and could do so again during large California quakes.

But — thanks in part to data gathered by CGS — the state’s building code requires that newer structures can survive high levels of seismic shaking. That ensures lives are protected even if the structure needs repairs after the quake.

Another CGS program identifies zones that may be prone to quake-caused dangers such as surface fault rupture, landslides, and liquefaction (the ground behaving like quicksand) and requires local governments to consider those potential hazards before new construction occurs to minimize the hazards.

Perhaps surprisingly, two-thirds of earthquake-related injuries are the result of an unsecured object hitting someone. During the 2014 Napa Earthquake, the only fatality occurred when a television set flew off its stand and struck a woman in the head.

That’s why the ShakeOut drill focuses on dropping to the ground and getting under a sturdy piece of furniture and hanging on to it, to protect your head and body.

Do Prepare a Go Bag, Don’t Stand in a Doorway

The idea of standing in a doorway is obsolete, dating to a time when many structures were made of adobe and the doorframe was the sturdiest part. Standing in a doorway does not provide additional protection. You’re in danger of being trampled by people trying to get outside — another thing to avoid while a building is still shaking, since glass or masonry may be falling from above.

Use the ShakeOut to not only practice the drill, but to take stock of your surroundings, whether at home or in the office.

Drop, cover, and hold on animation shows how to ShakeOut on Oct. 21.

For example, envision yourself in in bed or at your desk; are there objects that could tip over or fall off the wall and hurt you? Do you have a good place to drop, cover, and hold on? Do you have a “go bag” — also essential for wildfires and other disasters — and a few days’ worth of essentials like food, water, and medicine stockpiled?

Remember: California is earthquake country. Our state is progressing toward providing residents with a few seconds of warning prior to seismic shaking. Still, a little bit of forethought and practicing drop, cover, hold on will go a long way to keep you and your loved ones safe. Learn more about how to prepare.

CGS has a new Twitter account! Follow to stay current with CGS’ hazard and watershed management work. Follow Department of Conservation’s Facebook, Twitter, and Instagram for more on DOC’s role in managing California’s hazards, watersheds, and carbon while supporting the state’s economic development.

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