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New method can aid nuclear explosion detection

����vlog���� scientists are presenting their work at the American Geophysical Union’s fall meeting in New Orleans this week. This article is part of a series highlighting UAF research from the world’s largest Earth and space science meeting.

A UAF researcher has devised a method to improve detection of distant explosions, including nuclear detonations, by taking advantage of widespread single-microphone infrasound monitors.

Postdoctoral researcher Alex Witsil at the UAF Geophysical Institute’s Wilson Alaska Technical Center has created a library of artificial explosion signals to train computers to detect real-world explosions.

Using the library, real explosions can be detected amid background noise collected by single-channel microphones that record infrasound —  sound carried at wave frequencies below what humans can hear.

Today, detection algorithms generally rely on infrasound arrays that make use of multiple microphones close to each other. For example, the international Comprehensive Test Ban Treaty Organization, which monitors nuclear explosions, has infrasound microphones deployed worldwide. But they are of the multiple-microphone type.

“That's expensive, it's hard to maintain, and a lot more things can break,” Witsil said.

Using single infrasound microphones increases detection capability because they’re already in place for other uses. Their associated computers can be trained to recognize explosions by using artificial explosion signatures similar to the library Witsil created.

“What the work was meant to do was to detect large explosions, whether that's nuclear or chemical,” Witsil said. “The methods we have worked out will allow monitoring agencies to detect explosions from distances of upward of a couple 100 kilometers.”

Witsil’s work is supported by the Nuclear Arms Control Technology Program at the U.S. Defense Threat Reduction Agency.