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USGS reports small earthquake near Wisconsin city plagued by mysterious booming noises

MILWAUKEE - Federal geologists confirmed Thursday that a minor earthquake occurred this week near the eastern Wisconsin city where researchers have been investigating a series of unexplained booming sounds.

The U.S. Geological Survey said the 1.5 magnitude earthquake struck Tuesday just after midnight in Clintonville, a town of about 4,600 people about 40 miles west of Green Bay.

Geophysicist Paul Caruso told The Associated Press that loud booming noises have been known to accompany earthquakes. He said it's possible the mysterious sounds that town officials have been investigating are linked to the quake.

"To be honest, I'm skeptical that there'd be a sound report associated with such a small earthquake, but it's possible," Caruso said.
Earthquakes can generate seismic energy that moves underground at thousands of miles per hour, producing a sonic boom when the waves come to the earth's surface, Caruso said.

The U.S. Geological survey says earthquakes with magnitude of 2.0 or less aren't commonly felt by people and are generally recorded only on local seismographs. Caruso said the Tuesday earthquake was discovered after people reported feeling something, and geologists pored through their data to determine that an earthquake did indeed strike.

Local residents have reported late-night disturbances since Sunday, including a shaking ground and loud booms that sound like thunder or fireworks.

City officials investigated and ruled out a number of human-related explanations, such as construction, traffic, military exercises and underground work. The town has scheduled a news conference for Thursday at 6 p.m. but hasn't said what will be discussed.

http://www.startribune.com/local/143878936.html