Only 15 of state's 3,000 landslide zones monitored by high-tech warning system

by: Graham Johnson Updated:

ACME, Wash. - The Oso landslide killed more than 40 people, and it raised questions about whether the slide-prone hill should have had a warning system. 

Washington is full of dangerous hillsides, but few systems to get people out of harm's way.

There is one in the tiny Whatcom County town of Acme. Behind the town, a laser gauge watches Jones Creek during the rainiest months.

"If there's a sudden drop that's when it trips the gauge," said Holly Salkeld of Whatcom County Fire District 16.

A drop in the water level could mean a landslide blocks the creek upstream.

There are several unstable slopes above Acme. A slide could form a pond in a steep canyon. When it overflows, debris could come right down on the town.

"You're talking logs, boulders, everything could end up in the valley down here," said Battalion Chief Frank Hathaway.

He pushed for the system because there's no other way to know what's happening on the hillside.  The sensor pages fire commanders, who can warn the town of 200 with a siren and phone calls.

"It's easier to get people out than it is to rescue them," Hathaway said.

The gauge is run by the U.S. Geological Survey, the federal agency that studies landslides.

USGS hydrologist Rick LaHusen showed us the type of monitor placed on the Oso slide after the disaster.  

LaHusen uses instruments in California for real-time monitoring of a landslide in the Sierras.  If scientists see warning signs, they can call the Highway Patrol to close the road below.

"Typically, things will start cracking and there's some incipient motion before they break free and go catastrophic," LaHusen said.

That early movement is how landslides can be predicted.

"You can't take a very, very large mass of earth and accelerate it from zero to 60 mph instantaneously," LaHusen said. "It's got to have some kind of acceleration period."

Although monitoring technology exists, it's rarely used in this country.

There are lots of hillsides with landslide potential, but monitors only work if give they can people a meaningful warning.

And then, there's the money.  The entire nationwide USGS budget for landslide monitoring is just $3.5 million.

The agency's focus is researching slides, not providing warnings.

The Washington State Department of Transportation currently monitors as many as 15 slides near highways and up to 40 more on an as-needed basis.

As for the rest of the 3,300 hazardous slopes in the state database, WSDOT relies on passing maintenance crews to notice signs of trouble.

WSDOT had been monitoring a slide on the other side of State Route 530 in Oso.

But the hill that actually gave way was not in the state database, because it was more than a mile from the highway now buried in debris.

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