GREAT FALLS — Montana is among the top 10 states with the greatest amount of seismic activity throughout the United States. The Intermountain Seismic Belt runs from the northwestern Montana through Yellowstone National Park. The devastating earthquake in Turkey and Syria is a reminder to anyone living in close proximity to a fault line, including many Montanans, to be prepared for a tremor.
As of Wednesday evening, more than 12,000 people have been killed and tens of thousands are injured or missing.
According to Mike Stickney, the Director of Earthquake Studies at the Montana Bureau of Mines and Geology, the main shock occurred on the East Anatolion Plate near a triple junction, where three plates meet. The nearest example of a triple junction is the San Andreas Fault in California.
Despite not having a triple junction, Montana is no stranger to powerful earthquakes. The 7.2 magnitude Hebgen Lake earthquake and the 1935 Helena earthquake come to mind for many Montana historians and longer-term residents.
While there are many older, high-rise buildings in Turkey and Syria, Stickney says Montana's infrastructure is also susceptible to larger earthquakes.
"Most of the bigger Montana cities have some solid brick buildings that are multi-story. If they were built more than 50 years ago, before modern building codes allowed for that type of seismic shaking that can accompany a larger earthquake, I would say those buildings are definitely vulnerable to earthquake damage," Stickney explains.
The impact on the ground for a higher magnitude earthquake does not have a linear rise. "Every one magnitude you go up on the Richter scale, the ground shaking increases by a factor of 10. So, a magnitude of 5 shakes 10 times harder than a 4 and 100 times greater than a 3," said Stickney. Thus, there is even a large difference between the impact of the 7.3 magnitude Hebgen Lake earthquake and Monday's 7.8 magnitude earthquake in Turkey.
Seismologists say that while there is still no way to accurately predict an earthquake, the quieter period seen in the western United States the last several decades won't last forever. Stickney noted, "Every one of these tremors is a reminder that we do live in earthquake country and it's best to be prepared for that."
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The intermountain seismic belt, which runs through the western third of the state, is where the majority of the earthquake activity occurs in Montana. The vast majority of quakes are very small, and rarely felt by people.
However, there have been some notable earthquakes in Montana’s history, including the 7.3 magnitude Hebgen Lake earthquake on August 17, 1959. The earthquake triggered more than 160 new geysers throughout Yellowstone National Park. There were also around 28 fatalities from a rockslide in Madison Canyon.
And on July 6, 2017, one of the strongest earthquakes to hit Montana in decades shook the community of Lincoln northwest of Helena. It was centered 5.5 miles southeast of Lincoln at a depth of about 2.6 miles. People reported feeling the 5.8 magnitude quake across Montana and the northwest, with some reports coming from as far away as Vancouver and Lethbridge, Canada. It has caused some minor damage, but no fatalities or serious injuries.
The plains of central and eastern Montana are much less prone to quakes, but there have been a handful of significant ones reported.
According to the USGS, a 5.3 magnitude earthquake struck northeastern Montana on May 15th, 1909. Several smaller quakes have been recorded in Roosevelt County, including an estimated 4.5 magnitude quake in the town of Froid that resulted in some damage to a grain bin back in 1943.
Although it has been some time since the state has seen a destructive earthquake, small quakes occur several times every day. Click here to learn more about earthquake preparedness.