SPECIAL REPORT: USGS Relaunches Early Warning System For Landslides

In Oakland and on the many hillsides throughout the Bay Area, the recent heavy rains have already spawned small mudslides.

The fear many homeowners have is larger, more dangerous slides like the one that killed a man in his Mill Valley backyard four years ago could happen in the wake of a wet winter storm season.

"If earth starts moving all you can do is get out of the way. And do that fast," said Ron Marinoff of Marin.

The fear of landslides is why Daniel Chaffin said he often spends rainy days out in his yard in Marin's Lucas Valley near San Rafael checking to see if beauty might suddenly become a beast.

"I'm out several times with an umbrella and raincoat looking out through the gate to see what is happening," said Chaffin.

Chaffin -- like perhaps tens of thousands of Bay Area residents who live in harm's way of a hillside collapse -- said he'd sleep better knowing there was an early-detection system for landslides.

The U.S. Geological Survey at one time did monitor several Bay Area hills for landslides. But in 1995, the USGS ended the program due to budget cuts.

Back then, they used old-fashioned rain gauges to measure the moisture in the hills. But now, using new federal stimulus funds, geologists at the USGS in Menlo Park are resurrecting the program.

This time, the system will utilize high-tech landslide detection equipment.

"We need to know how water is going into the soil during a storm. This little device is a soil-moisture sensor," said Jonathan Stock of U.S. Geological Survey.

Several weeks ago, geologists planted the sensors in an area of the East Bay hills along Niles Canyon. They plan to do the same in Lucas Valley in Marin County and in the Santa Cruz mountains during the next few weeks.

"We need to put little thermometers into the soil that measure not temperature, but what the water pressure in the soil is. How much water there is [in the soil] what could destabilize that piece of ground," explained Stock.

Those measurements are monitored by computers at the USGS in Menlo Park. As of two weeks ago, graphs showed Niles Canyon was wet, but nowhere near going wild.

"We would worry if we saw our this line spike up to positive water pressure which means we are getting towards liquification when the water pressure pushes the grains apart. When that happens, the strength of that soil goes away suddenly and you can generate landslides," said Stock.

Geologists are hoping that measurements at one location will help them predict how other hills in the area are holding up. Even though the program is in its infancy, many public safety officials hope that if it's successful the detection system could save lives.

"We're expecting science is going to try to quantify this threat so we know generally if the landslide threat increases because of rainfall," said Chris Godley, who works as Marin County Emergency Services manager. "It is going to be very helpful to know for public safety and communicate that risk to the public."

Chaffin for one was pleased to hear about the warning system being relaunched.

"Anything that gives us more advance warning of untoward weather events is going to be helpful. We live in this part of California in an essentially unstable landscape environment," said Daniel Chaffin.

Geologists stressed this system is still experimental. But their hope is that someday soon they will be able to learn when certain Bay Area hills have had so much rain that those living down below need to get out.