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Sheridan inventors listen for avalanches
Engineers use valley avalanche paths to test prototype low-frequency listening device.

By Angus M. Thuermer Jr.

A pair of inventors is using Jackson Hole avalanche paths to test a device that may be able to sense when snowslides occur in remote locations.

Two engineers from Sheridan have installed three prototype instruments near Glory Slide on Teton Pass and in two locations at the Jackson Hole Mountain Resort. They hope they can fine-tune their device, which uses Cold-War technology to detect low-frequency or infrasonic sounds so it will act as a listening post, sounding an alarm when an avalanche has occurred.

One obvious application would be to alert Wyoming Department of Transportation workers of an avalanche that ran down Glory Bowl, blocking Highway 22 over Teton Pass. Mark Weitz, one of the engineers working on the project, hopes his sensor will ultimately be rigged to sound an alarm in the middle of the night, closing gates on the highway and summoning workers to clear the road of debris before the commuting hour.

"That is the ultimate application ­ to try to control traffic, shut a gate, call the snow crew," Weitz said in a telephone interview from his Sheridan office.

While one might envision a simpler device to react to a Glory slide, the infrasonic detector could have a wide variety of other applications, said Bob Comey, an avalanche hazard forecaster with the U.S. Forest Service at the Jackson Hole Mountain Resort. For example, the device could come into play when firing avalanche artillery in bad weather or in the dark to reduce the slide hazard at the ski area. The instrument could tell ski patrollers which slide paths did not release as a result of the shooting ­ something they couldn't detect by sight from the gun station.

"If we got results out of shot seven and nine, but eight's still there, we need to keep vigilant on that," Comey said. Also, if a sensor were in the backcountry, forecasters might discover that slides are occurring at an alarming rate following a storm.

Forecasters then could issue an advisory saying "we're having 15 avalanches an hour," Comey said. Backcountry travelers would be that much more informed, he said.

Known as an "infrasonic avalanche detection system," the devices are being developed by Weitz and Ernie Scott, Sheridan residents and University of Wyoming graduates who work for Chinook Engineering. The research and development firm specializes in innovative measurements and is an arm of Inter-Mountain Laboratories, Inc., a company that has concentrated on mining and mineral exploration in Wyoming.

Weitz said the heart of the device is a microphone-like sensor that originally was developed to detect the detonation of nuclear devices around the globe. Such sensors have been used by U.S. military and intelligence agencies to determine that various countries have tested nuclear bombs.

Weitz said a scientist with the National Oceanographic and Atmospheric Agency got hold of one of the sensors and wondered what else it might record - tornados, storms, and so on. After setting it up in Boulder, Colo., the researcher collected sound data he could only correlate with one phenomenon - avalanches miles and miles away in Summit County.

The government then put out a proposal and offered a grant suggesting that the detector could be developed commercially for use as an avalanche detector. Weitz, 42, a backcountry skier, was intrigued "from the get-go."

He and and Scott applied to the government and received a $375,000 Small Business Innovation Research grant to develop a device.

The result is something that looks like an octopus but lives under the snow.

The microphone component is about the size of a basketball, Weitz said. Approximately eight noise filters, resembling 100-yard porous garden hoses, stretch from it. Then there's the computer to record the information. The instrument needs a power source and eventually will have a transmitter. The entire contraption can fit in a backpack.

Weitz said the low-frequency sound waves carry far. Therefore, the detector can be put in a safe location, away from avalanche paths.

"You can locate them away from the source," he said. "You can locate them out of harm's way."

The device is not an avalanche predictor. On a long slide path, it could be used to signal the start of a slide high up, possibly giving those below warning to evacuate. But that is neither the intent of the research nor its best use, Weitz said.

This year's work centers on identifying and isolating the signature or characteristics of the peculiar avalanche sound. Today, a person can figure out such subtleties watching a computer screen; teaching the computer to recognize the signal is more difficult.

"It's not a trivial task," Weitz said. "We've got some false detects."

Comey said nobody's sure what it is in an avalanche ­ snow crystals being destroyed or turbulence inside the slide ­ that makes the particular sound. But it is, apparently, distinct and something that travels a long way.

If the detector becomes a reality, Comey dreams of a series that could be installed across the ski area to help triangulate and pinpoint avalanches. But such sophistication may be years away, if it is achieved at all.

Meantime Weitz, Scott and Comey will tinker with their prototypes, seeking to interpret what the snowbound octopus hears. The project has been a joy and challenge, Weitz said.

"It's great we're getting paid to do this," he said. "It's great some Wyoming companies are getting involved [in technology] instead of poking holes in the ground."

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