HELENA- A 4.2 magnitude earthquake shook northern Lewis and Clark Co. Thursday afternoon.
The tremor struck south-east of Lincoln around 4:20 p.m. It was almost due north of the site of a 5.8 magnitude quake from July 6. It is the strongest tremor since a 5.0 magnitude aftershock on the same day as the July quake (originally this was reported as 4.9). That aftershock was recorded just five minutes after the initial quake hit.
There have not been any reports of damage or injury. Thursday’s earthquake was reportedly felt as far away as Whitefish.
The quake happened on the Great Montana Shakeout Day.” The Great Montana Shakeout is a statewide earthquake drill that occurs at 10:19 a.m.
Hundreds of earthquakes have shaken the Lincoln area since July 6 earthquake. Most recently on Oct. 15, magnitude 3.9 and 3.4 earthquakes shook the Lincoln area.
Other strong aftershocks were recorded on:
- July 08: 3.6M
- July 17: 4.0M
- July 23: 3.6M
- Aug 20: 3.6M
Since July 6, there have been 97 earthquake greater than 2.5 magnitude. There have been 721 earthquake greater than 1.0 magnitude since July 6
The July 6 earthquake was the largest in Montana in almost 100 years.
Montana is among the most seismically active states in the U.S.
The last time Helena was hit with a major earthquake was in 1935. It started with a small quake Oct. 3, followed by a 5.9 on Oct.12 and a devastating 6.2 on Oct. 18.
This is a developing story we will update you when we have more information.