Is Montana Primed for Another Big Earthquake?
The recent magnitude six earthquake in California may seem almost imaginable in Montana, but just 60 years ago, quakes of that scale occurred fairly regularly.
"If you look back at the earthquake history of Montana, we've had a number of earthquakes that were as big, or larger than the recent California quake," said Seismologist Mike Stickney from the Montana Bureau of Mines and Geology. "However, in Montana's case, they were all more than 54 years ago. Between 1920 and 1960, so, 40 years of Montana history, we were having a magnitude six or larger earthquake at least once a decade."
Montana’s earthquake zone is wide, and runs through many major cities.
"The earthquake belt or zone that runs through western Montana extends roughly from the Flathead Lake, Kalispell region in the northwest, it passes southeastward to Helena, and then southward down to the Yellowstone region. It's not a precisely defined zone, but it's roughly 60 to 100 miles wide," Stickney said.
In 1935, Helena was hit by two earthquakes over a magnitude six which killed at least four people and damaged 60 percent of the cities buildings.
The fact that Montana hasn't had a big earthquake for quite some time might lead one to believe that the state is primed for a big shaker, but Stickney says we really don't know at this point, because we don't how Montana has behaved over the eons of time.