Earthquake, aftershocks rattle western Montana

MISSOULA, Mont. - An earthquake struck western Montana around 12:30 a.m. Thursday. The National Weather Service in Great Falls said on Twitter that the shaking was felt as far away as 500 miles.

The U.S. Geological Survey says the the 5.8-magnitude earthquake hit about 6 miles southeast of Lincoln.

Here is the seismograph from the Black Hills, South Dakota seismic station:

USGS also reports several aftershocks centered in the Lincoln area:

Time Magnitude 11:54 p.m. 3.1 4:24 p.m. 3.8 9:27 a.m. 3.7 7:15 a.m. 3.6 5:46 a.m. 2.5 4:54 a.m. 2.9 4:44 a.m. 3.4 4:04 a.m. 2.9 1:31 a.m 3.9 1:27 a.m. 4.4 1:11 a.m. 3.5 1:08 a.m. 3.9 1:02 a.m. 4.5 12:59 a.m. 3.8 12:54 a.m. 3.5 12:48 a.m. 3.1 12:35 a.m. 4.9

The Lewis and Clark Sheriff's Office reports power in Lincoln has been restored, and there have been no reports of injury or damage in the area.

Viewers around western Montana, including Missoula, Butte, Bozeman, Gardiner, Kalispell Columbia Falls, Hamilton and as far as Spokane, Washington, and Stirling, Alberta, Canada, tell us they felt the quake.

We have received more than 1,000 comments from viewers on our social media pages.

A 76-year-old resident of Helena, which is about 34 miles away from the quake's epicenter, said it was the strongest seismic activity that he had ever felt. Ray Anderson said his wife told him the temblor woke up the dogs.

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Data from the Chamberlain Mountain seismograph shows a marked difference in seismic activity from Wednesday to Thursday.

Wednesday:

Thursday:

The following earthquakes are the three of Montana's largest earthquakes in the last century.

In August of 1959, a 7.5 quake killed 29 people and did $11 million worth of damage and became the largest earthquake to ever hit Montana.

In 1935, a series of several hundred quakes hit Helena. The state reports that quake damaged more than half of Helena's buildings.

In 2005, a 5.6 quake rattled Dillon and damages part of the old main hall at the University of Montana Western.

The following is from the U.S. Geological Survey information on earthquakes:

Events with magnitudes greater than 4.5 are strong enough to be recorded by a seismograph anywhere in the world, so long as its sensors are not located in the earthquake's shadow.

The following describes the typical effects of earthquakes of various magnitudes near the epicenter. The values are typical only. They should be taken with extreme caution, since intensity and thus ground effects depend not only on the magnitude, but also on the distance to the epicenter, the depth of an earthquake's focus beneath the epicenter, the location of the epicenter and geological conditions (certain terrains can amplify seismic signals).

Magnitude

Description

Mercalli intensity

Average earthquake effects

Average frequency of occurrence (estimated)

1.0-1.9

Micro

I

Microearthquakes, not felt, or felt rarely. Recorded by seismographs.

Continual/several million per year

2.0-2.9

Minor

I to II

Felt slightly by some people. No damage to buildings.

Over one million per year

3.0-3.9

III to IV

Often felt by people, but very rarely causes damage. Shaking of indoor objects can be noticeable.

Over 100,000 per year

4.0-4.9

Light

IV to VI

Noticeable shaking of indoor objects and rattling noises. Felt by most people in the affected area. Slightly felt outside. Generally causes none to minimal damage. Moderate to significant damage very unlikely. Some objects may fall off shelves or be knocked over.

10,000 to 15,000 per year

5.0-5.9

Moderate

VI to VII

Can cause damage of varying severity to poorly constructed buildings. At most, none to slight damage to all other buildings. Felt by everyone.

1,000 to 1,500 per year

6.0-6.9

Strong

VIII to X

Damage to a moderate number of well-built structures in populated areas. Earthquake-resistant structures survive with slight to moderate damage. Poorly designed structures receive moderate to severe damage. Felt in wider areas; up to hundreds of miles/kilometers from the epicenter. Strong to violent shaking in epicentral area.

100 to 150 per year

7.0-7.9

Major

X or greater

Causes damage to most buildings, some to partially or completely collapse or receive severe damage. Well-designed structures are likely to receive damage. Felt across great distances with major damage mostly limited to 250 km from epicenter.

10 to 20 per year

8.0-8.9

Great

Major damage to buildings, structures likely to be destroyed. Will cause moderate to heavy damage to sturdy or earthquake-resistant buildings. Damaging in large areas. Felt in extremely large regions.

One per year

9.0 and greater

At or near total destruction - severe damage or collapse to all buildings. Heavy damage and shaking extends to distant locations. Permanent changes in ground topography.

One per 10 to 50 years

Based on U.S. Geological Survey documents.