SAN FRANCISCO (KCBS) — This year’s drenching rain had many concerned about the possibility of a landslide, but one expert from the U.S. Geological Survey (USGS) said they don’t necessarily happen during the rain and that soil is like a sponge, even in a downpour.

However, once you get to the point of saturation, Dr. Jonathon Stock, a research geologist, said the water starts to drip out.

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Exerting the kind of pressure that will then cause a slide so knowing how much rain is coming isn’t enough to predict landslides. That’s why the USGS is monitoring instruments at four sites in the ground in the Bay Area to see if those sponges are filling up.

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“These are places where landslides have occurred during big historic storms like 1982 or 1998,” Stock said.

Those sites, 72 altogether, in the North Bay, East Bay and two of them on the peninsula are 100 percent of the way to “basically being completely saturated,” according to Stock.

His advice if you’re in a vulnerable area is to check the USGS website for warning tips and talk to neighbors who have lived in those areas for a long time.

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