By Judy Woodward
Every month, the reference librarians at the Roseville Library receive dozens of questions from the public. Here is one of the more interesting queries we received recently:
Q: How likely is it that a really big earthquake will hit Minnesota?
A: It’s quite unlikely. According to scientists at the University of Minnesota, “Minnesota has one of the lowest occurrence levels of earthquakes in the United States, but a total of 20 small to moderate earthquakes have been documented since 1860.”
The largest temblor ever felt in Minnesota took place in Morris in 1975. It measured 4.6 to 4.8 on the Richter Scale. That was enough to knock things off shelves and damage some chimneys, but not to spark the kind of calamitous destruction that earthquakes cause in more seismically unstable parts of the world.
Although Minnesota is unlikely to be in danger, the Midwest doesn’t escape earthquake threats altogether.
The well-known New Madrid fault in Missouri produced a series of three gigantic earthquakes in late 1811 to early 1812. The American heartland was very lightly settled then, so the damage wasn’t nearly as severe as it would be today. But the quakes measured between 7.0 and a powerful 8.6 on the Richter scale. While there exist no records that the New Madrid quake was felt in Minnesota, the destruction closer to the epicenter in Missouri was overwhelming and the shaking was felt as far away as the East Coast.
Could another New Madrid earthquake be coming up? Possibly. The U.S. Geological Survey has forecast a 7%-10% probability for an earthquake of a 7.5 to 8.0 magnitude along the 120-mile fault within the next 50 years. (Sources: Internet resources including the website of the Minnesota Geological Survey, https://cse.umn.edu/mgs/earthquakes)
Judy Woodward, who lives in St. Anthony Park, is a reference librarian at the Roseville Library, 2180 N. Hamline Ave. The library’s general phone number is 651-724-6001.