By Jasen Lee

Deseret News

In the world of high-tech solutions to virtually any of life's problems, researchers at the University of Utah announced Thursday that they have devised a patent-pending method of locating trapped miners that is surprisingly low on the technology scale.

The method involves installing iron plates and sledgehammers at regular intervals inside mines and placing sensitive listening devices on the ground above the site of the plates.

The method records "seismic fingerprints generated by a trapped miner banging on the mine wall and uses those fingerprints to locate him," Gerard Schuster, professor of geology and geophysics at the University of Utah and co-author of the study, said in a news release.

"Low-tech requirements for the miner can be good, because not much is available to the miner except the bare minimum of devices after a mine disaster," Schuster said in an e-mail to the Deseret News. It makes sense to record seismic vibrations using the strong, direct waves emitted by the miner's hammer to locate the miner, he said.

Sherif Hanafy, adjunct associate professor of geology and geophysics at the U., said previous research had focused on using light waves to send signals to a source outside of a mine, while this research targets seismic waves.

"Light cannot travel through the rock, but seismic can," said Hanafy, who co-authored the study.

Tracking seismic waves through rock underground proved to be quite successful in the testing performed, he said.

One test was in a utility tunnel beneath the U. campus, and another was conducted in much deeper tunnels in an abandoned copper mine near Tucson, Ariz., Hanafy said.

"We got 100 percent accuracy," he said.

The study's findings were published in the latest issue of "The Leading Edge," a journal of the Society of Exploration Geophysicists.

Researchers are trying to contact an operator of a working Utah coal mine to conduct more-advanced underground testing, Hanafy said.

"We hope to test as soon as we can, so that it can be ready for applications," he said.

Garth Nielsen, director of the state's Office of Coal Mine Safety, called the findings "interesting" and said he would contact the researchers to further investigate the potential uses of the communication method.

The system would be installed incrementally as a mine is excavated, according to University of Utah spokesman Lee Siegel.

Inside mine tunnels, "base stations" are built at numerous points, depending on each tunnel's length. At each station, a 4-by-4-inch iron plate is bolted to the wall, and a sledgehammer is placed near each plate.

On the surface, cables are strung along the ground above each tunnel or shaft, and "geophones" are spaced at regular intervals along the cables. Geophones are devices that "listen" for seismic waves created when miners use a sledgehammer to bang on an iron plate, Siegel said.

Once the system is installed, each base station is "calibrated," meaning its plate is hit and the seismic waves are recorded by the geophones overhead. Each base station has a distinct seismic-wave fingerprint, so if miners are trapped and bang the metal plate at the nearest base station, the resulting seismic recording will allow rescuers to determine precisely which base-station plate was struck, Siegel said.

In the case of deep underground mines like those found in Utah, "it might be necessary to boost the power of the source by replacing the hammer with a small battery-powered vibrator device," Schuster said.

A full system would include about 100 geophones and 100 base stations, and it would cost about $100,000 for a typical mine, he said.

Schuster also said the system could be expanded to allow two-way communications instead of just signals from trapped miners to rescuers on the surface. Two-way communication would require a computer and geophone at each underground base station to pick up signals from people on the surface, he added.

"It's like having a fire extinguisher on every floor," Schuster said.

The research for the miner-locating method was triggered by the tragic Crandall Canyon Mine collapse in August 2007. Six miners died in the collapse, and three rescuers died 10 days later trying to reach them. The coal mine was permanently shuttered, and the miners' bodies were never recovered.

E-MAIL: jlee@desnews.com