Two more quakes hit Marion
The Marion area was rattled by two more earthquakes Sunday night and Monday morning — making a total of four quakes in Northwest Montana in less than three weeks.
However, the seismic activity lately is completely natural, according to Mike Stickney, director of the Earthquake Studies Office with the Montana Bureau of Mines and Geology in Butte.
“The area south of McGregor Lake is experiencing what we call an earthquake swarm,” he said. “Swarms have had a historical presence in the area.”
Earthquake swarms are several small- to mid-sized earthquakes that happen over a period of time, Stickney said. That period could be a few hours or days up to several months.
“There’s no way to predict when the bursts of activity will happen,” he said.
On Sunday night there was a 3.0-magnitude quake at 10:40 p.m., with an epicenter 33 miles southwest of Kalispell, followed at 1:13 a.m. Monday by a 3.5-magnitude quake centered 31 miles southwest of Kalispell.
‘Felt the 3.5 quake today on McGregor Lake,” Wanda Thein posted on the Daily Inter Lake Facebook page. “Shook things on the shelves and pictures on the wall. A little scary since we have felt three of them here within the last month.”
Previous noteworthy earthquakes were a 4.0-magnitude quake near Marion on Nov. 11 and a 3.9 near Columbia Falls on Nov. 14. The Columbia Falls quake was felt by thousands of people across the Flathead Valley.
Montana is one of the most seismically active states in the country due to its mountainous area, according to the U.S. Geological Survey website. However, much of this activity is small and not felt by residents.
Stickney said it is unknown exactly what has caused the recent swarm of earthquakes but attributes them to pressure under the Earth’s crust that cannot be released in a single quake.
“Swarms are not well understood,” he said. “Usually they’re common near a volcanic area but can also be present in areas well away from volcanic area.”
While he said this is no cause for alarm, Stickney said he wouldn’t be surprised if the activity continues over the next several weeks or months.
Similar swarms have happened around here in the past. In 1995, a swarm took place over several weeks near Kila, with quakes between 4.0 and 4.5.
One of the area’s largest swarms took place near Big Arm in 1969, when a 4.7 magnitude quake was followed by 325 smaller quakes over the next several years.
People are advised to take precautions in their homes since an earthquake can happen at any time. Heavy objects should not be placed on shelves where they could fall, and Stickney recommended strapping hot water heaters to walls to prevent damage.
“This is a reminder that we do live in earthquake country and regular precautions need to be taken,” he said.
Reporter Brianna Loper may be reached at 758-4441 or by email at bloper@dailyinterlake.com.