DOOR COUNTY (NBC 26) — The U.S. Geological Survey reported an earthquake southeast of Sturgeon Bay at 9:18 a.m. Friday morning.
- The quake registered a 2.9 on the logarithmic Richter scale — an expert says a quake would need to be higher on the scale to be felt by many, or cause damage
- The quake is the highest magnitude ever registered by USGS in northeast Wisconsin, and second-highest in state history, as the Milwaukee area experienced a 3.8 in 1947
- The expert says ancient cracks in the earth's crust can occassionaly shift to release pressure, causing an earthquake
- Video shows a map of quakes in state history
(The following is a transcription of the full broadcast story)
Did you feel it? We're in Sturgeon Bay, and an earthquake happened this morning — just 24 miles from here, in that general direction, out under Lake Michigan.
What happened at 9:18 Friday morning, seven miles below the surface, is rare.
"This has got to be a first," Ken Graves said.
But not unheard of.
We spoke with an expert at UW-Green Bay who says major plate boundaries usually get more seismic activity, but smaller cracks in the Earth's crust exist all over the country.
"We think of earthquakes is happening in California or Japan, but everywhere has these little faults and fractures and they just get a little overstressed," assisant professor of geoscience Shawn Malone said. "They'll slip a little bit and you get an earthquake, like we had."
This particular quake was only a 2.9 on the Richter scale.
About 40 people reported feeling it on the U.S. Geological survey's website, but most people we spoke with in Door County say they didn't notice.
"We didn't feel a thing," Graves said. "We were at home at the time, and we got up here about 1:00, but nothing. We were on the beach all day, and the lake was really flat."
Malone says a quake would need to be quite a bit stronger to cause any real damage.
"You go up to a six [on the Richter scale], and that's probably gonna cause at least some structural damage," Malone said. "My bookcase probably isn't secured well enough for that."
Friday's was just the eighth earthquake registered by the USGS in Wisconsin in the past century — and second this year.
There was a 2.5 magnitude quake near Crandon in January, and four small ones near Iola in 2018. So you probably don't need to worry about a major quake.
"Very unlikely," Malone said. "I never want to say anything's impossible, but you probably don't need to buy earthquake insurance."
While experts say there's always the possibility an earthquake could cause aftershocks hours and days after it happen, they say it's unlikely this earthquake would cause any damaging aftershocks.
