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A study is saying California is in an “exceptional” hundred-year earthquake drought and is long overdue for a powerful magnitude 7.0 or greater quake along its three, most feared faults.

Researchers from the U.S. Geological Survey (USGS) poured through paleoseismic records of the past 1,000 years of California’s three highest slip-rate faults (San Andreas, San Jacinto and Hayward), and determined that it’s “exceptional” that there has been an absence of ground-rupturing earthquakes on any of them in the past 100 years.

While there have been major quakes within the state during the past century, they weren’t along the three mentioned faults which carry most of the slip between the Pacific and North American tectonic plates.

In a press release, USGS researcher Glenn Biasi said, “If our work is correct, the next century isn’t going to be like the last one, but could be more like the century that ended in 1918.”

Between 1800 and 1918, there were eight ground-rupturing earthquakes — the type that pose a greater risk to structures than the temblors that happen deep below the Earth’s surface.

The 1906 San Francisco earthquake along the San Andreas in Northern California was a ground-rupturing quake with an estimated magnitude of 7.9. The tremor destroyed most of the city and left at least 700 dead, according to the USGS.

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Photograph of the San Francisco earthquake in California, 1906

The San Francisco quake of 1906 is considered one of the deadliest quakes in U.S. history, and the last quake of this magnitude to happen in the last century.

In comparison, the 1994 Northridge earthquake was “only” a magnitude 6.7 quake, which pales in comparison to the tremors of the previous century.

The researchers say the likelihood of going for a century without any major activity along these three major faults is slim, around a 0.3 percent chance.

According to records, there should be typically three to four large ground-rupturing quakes of at least magnitude 6.5 each century. The last time California experienced a major, ground-rupturing quake along the three major faults was in 1918 when a magnitude 6.5 temblor ruptured the San Jacinto fault in Riverside County.

While no one knows when the earthquake drought will end, it will at some point and without warning. Here are seven crucial tips from American Survival Guide that can help you prepare for an earthquake