USGS confirms 1.5 magnitude earthquake in Clintonville

CLINTONVILLE - After three days of mysterious booming noises and vibrations in the ground, things were quiet in Clintonville Wednesday night and Thursday - with the exception of a bombshell announcement.

The United States Geological Survey this afternoon confirmed a 1.5 magnitude earthquake hit the Waupaca County community Tuesday at 12:15 a.m.

Clintonville City Administrator Lisa Kuss told the community Thursday "the mystery is solved." She says the rumbling can be explained by the micro earthquake that struck earlier this week.

She says representatives from the USGS describe the cause as a swarm of several small earthquakes in a very short time.

The rumblings were first heard and felt on Sunday night. They intensified early Monday morning and continued on Tuesday. Few calls have come in since Wednesday morning.

Overall, Clintonville police dispatch has answered more than 600 calls about the mysterious booms.

FOX 11's Ben Krumholz spoke with Paul Caruso, a geophysicist from the U.S. Geological Survey this afternoon.

Caruso says the USGS is looking into if the other booms and shakes in Clintonville were also earthquakes. However, he says even if more quakes are found, the 1.5 magnitude quake will likely be the largest.

Caruso tells FOX 11 it is the smallest earthquake he has ever heard of that people actually felt. He says similar earthquakes happen all the time in California, but people never feel them. Caruso says it is because the rock in Wisconsin is very old and well consolidated. He says the 1.5 magnitude quake would have likely only been felt within a few blocks around its epicenter.

"Our seismometers did not detect it initially, so we got reports that people felt something and we went back and looked at the data from that time and in that place and we finally were able to get enough data together to locate the earthquake. It was very small and very hard to locate," said Caruso.

"So does this explain the booms and shakes people felt days before it and a little bit after?" asked FOX 11's Ben Krumholz.

"There may have been additional quakes and we are looking into that right now, trying to locate those if there were additional quakes," Caruso replied.