Residents get reassurances, few answers; Clintonville meeting dispels some rumors

The Shawano Leader, By Tim Ryan; tryan@shawanoleader.com

Leader Photo by Tim Ryan
About 400 Clintonville area residents turned out Wednesday for a meeting about the unexplained booming noises and tremors reported in the city over the last few days.

Clintonville residents on edge after three days and three nights of strange noises and tremors left a community meeting Wednesday night with few answers, but plenty of assurances from officials that they were doing all they can.

Several hundred people, flanked by rows of television cameras, crowded into the auditorium at Clintonville High School to hear city officials address a mystery that has become a national news story.

“The city team of staff and elected officials are doing everything we can to solve the mystery behind the booming, thunderous vibrations that are being felt throughout our city,” City Administrator Lisa Kuss said.

Scores of homes have been shaken three nights in a row and residents awakened by noises variously described as explosions, thunder, booming and jackhammer-like rattling. The activity has also been heard and felt to a lesser degree during daylight hours.

City officials say there is no indication of any danger, but members of the American Red Cross were on hand at Wednesday’s meeting, along with mental health counselors, who Kuss said would be available for residents dealing with stress and sleepless nights during the ordeal.

Kuss sought to ease concerns from some residents of a possible earthquake looming, saying the Level 3 earthquakes typical in Wisconsin are generally not even felt above ground.

“We have confirmed this is not typical earthquake activity,” she said, adding that the activity seems to be originating within a few hundred feet of the surface rather than the mile or more down where earthquakes are triggered.

Another concern raised by several residents was the possibility of a large-scale sinkhole, but Kuss said the earth beneath Clintonville — layers of sand, gravel and clay on top of granite — made that scenario unlikely, according to geologists.

“After three days, if there was any indication of sink holes, we should be seeing some change in the landscape,” Kuss said.

Kuss also dispelled rumors of underground lakes, rivers or caverns, saying there was no indication from geologists of any of those things.

Most likely, she said, is the possibility of some natural phenomenon occurring under the ground, possibly linked to an earlier and warmer than usual spring.

“There is some reason to believe the warm spring is shifting the granite rock under our community,” Kuss said.

The city has hired engineering firm Ruekert-Mielke of Waukesha, at a cost of $7,000, to install four monitors in locations still to be determined in the city.

The hope is the monitors will determine a pattern and epicenter and then depth of the vibrations that might lead to some solution. But, Kuss said, the city could not promise results.

“There is no guarantee this information will be useful or that it will solve our problem,” she said. “It is possible we will never have a definitive answer.”

Most of what Kuss presented to attendees Wednesday were the number of possible explanations that have been eliminated over the past several days, including problems with the water and sewer systems; elevated gas levels; area blasting or mining; closed landfill or dam structures; industrial businesses; military operations; and geological occurrences such as isostatic rebound or cryoseism.

Isostatic rebound is the upward movement of the Earth’s crust following a large scale sinking of the crust under a heavy weight, such as ice.

Cryoseism, also known as a frost quake, can be caused by a sudden cracking action in frozen soil or rock saturated with water or ice.

Kuss, addressing a question of whether there should be an evacuation plan, said there was no indication at this time that the incidents of the last three days pose any kind of danger.

“At this point, and we’ve indicated to that the last three days, we do not feel that it’s necessary to evacuate,” she said. “We’re hoping that it’s getting better, not worse, and at this point if we felt it was necessary to evacuate, we would indicate that.”

Kuss said city staff and county emergency personnel already have plans in place to deal with such things as tornadoes, and would apply the same measures if necessary.

“We would in a heartbeat have things in place for you if things got worse, places for you to go, places for you to evacuate,” she said.

The city has had some 600 calls since late Sunday night about the noises and vibrations. Initially, the incidents seemed to be centered in the northeast quadrant of the city, but spread south and west over the next two days.

The subsequent incidents were said to be less severe, however, raising hopes the phenomenon could just disappear even if it’s never explained.

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