California sees 600 landslides from atmospheric river storms

OAKLAND, Calif. - They stop trains, block roads and create clean up nightmares for residents, businesses and municipal crews.

Landslides are dangerous, often unpredictable and downright messy.

Not surprising given the amount of rain, the state has seen in the last three weeks, California’s Geological Survey found that since December 30, there have been 600 reported landslides statewide. 

"Right now, we're kind of at the threshold of starting to see not just little blowouts and small landslides, but we’re starting to see some of the larger landslides starting to move. And that’s when it gets really scary out there," said Jeff Nolan, a Santa Cruz County Geologist.

Shallow landslides can occur with a few inches of rain.

But as the ground saturates deeper and deeper large pieces of land can be on the move.

And the steeper the grade the bigger the chance.

"You’re dealing with gravity that’s trying to pull down that side of the mountain,’’ said Daniel Goodrich with the Mineta Transportation Institute in San Jose. 

In Alameda County trains were stopped near Niles Canyon twice this week because of landslides.

The USGS has a map pinpointing hotspots and the level of risk statewide. The areas of concern include the Peninsula, south of San Francisco, the Santa Cruz Mountains, and the North Coast or areas where wildfires previously burned.

Much like an earthquake, a landslide can happen without warning.

Experts say rainfall-induced slides are more likely to occur on steep slopes, those eroded by construction, slopes with poor drainage or on slopes where vegetation has been burned or removed. Locations with previous landslides are at a higher risk. 

That's what happened in the Berkeley hills where a handful of homes were red-tagged in recent days because they are dangerously close to a recent landslide. Others were in the path of the landslide itself. 

"You’re pretty much at Mother Nature’s mercy at that point. Your house is where it is, and the earth is what it is," Nolan said. 

Geologists say it’s important to know where the runoff from your property is going and try to control it.

If you are on a hillside and hear creaking or cracking, trees falling or roaring sounds – check it out immediately or consider leaving right away.

Brooks Jarosz is an investigative reporter for KTVU. Email him at brooks.jarosz@fox.com and follow him on Facebook and Twitter @BrooksKTVU