Wisconsin likely safe from hurricanes, but what about earthquakes?

Posted at 7:36 AM, Aug 22, 2019
and last updated 2019-08-22 23:58:46-04

The Atlantic and Gulf coasts are bracing for peak Atlantic hurricane season, and the West Coast is still on its toes for aftershocks from recent earthquakes. This certainly is a time we're reminded how lucky we are to live in Wisconsin. Or are we really?

First things first: A hurricane has never hit Wisconsin. To be frank, one never will, either. But that doesn't mean we can't feel the effects.

Several hurricanes to make landfall along the Gulf Coast will race north toward the Midwest. In recorded history, a few of these hurricanes almost maintained tropical storm status when reaching Wisconsin.

We also monitor strong low-pressure systems that develop over the Great Lakes, but the waters are just too cold to produce a hurricane.

There is one exception that some speculate. Twenty-three years ago in September, an intense storm, now unofficially known as Hurricane Huron, actually developed an eye over Lake Huron. This storm produced 73 mph winds but did not form the warm core needed to classify as a tropical system.

Earthquakes are a different story. We can and do feel earthquakes. There is only one documented earthquake to originate in southeast Wisconsin.

On May 6, 1947, an estimated earthquake of 4 magnitude shook downtown Milwaukee. The quake was strong enough to shake buildings and break windows.

Most of the earthquakes we feel here in southeastern Wisconsin originate in northern Illinois, where there are a few active faults.

To feel larger — and more devastating — quakes, we have to travel even farther south to the New Madrid Zone that stretches from western Tennessee to Missouri.

In 1811 and 1812, there were a series of 8 magnitude or greater quakes. An earthquake this strong would be devastating for the nearby large cities of Memphis and St. Louis.

More important for us, waves from an earthquake this strong would travel easily through the Midwest bedrock, and we would easily feel them here.

Seismologists believe we could actually sustain some damage from a major earthquake in the New Madrid Zone.

These seismic experts are split on whether a big one will occur again. The U.S. Geological Survey estimates there is a 28% to 46% chance of a magnitude 6 or greater earthquake hitting the New Madrid Zone in the next 40 years.

It would be smart to prepare for such an event by securing heavy items including bookshelves, dressers and your water heater.