Earthquake near Helena Valley Northeast, MT

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 11 km (7 mi) from the epicentre. In Helena Valley Northeast, 23 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

Earthquakes near other towns within 30 km: Helena Valley Northwest, Helena Valley Southeast.

How big was it?

This earthquake released about 6.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 2,300,000× the energy of this one
2. Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
3. Around the size people start to feel M 3.0 140× the energy of this one
4. This earthquake M 1.6 about 6.6 lb of TNT

Energy from the Gutenberg–Richter relation (log₁₀E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

For this area

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

1. 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 28 km SSE of this epicentre Oct 19, 1935
2. 5.9 2 km ENE of Helena, Montana · 33 km SW of this epicentre Oct 12, 1935
3. 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 34 km SSW of this epicentre Oct 31, 1935
4. 5.0 2 km ENE of Helena, Montana · 33 km SW of this epicentre Nov 28, 1935

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 46.8390, -111.7390. Map © OpenStreetMap contributors.

Nearby places

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

55 earthquakes have been recorded within 50 km since this one.

1. 1.8 23 km WSW of Craig, Montana 13:30 UTC
2. 1.6 2 km NW of Montana City, Montana 19:42 UTC
3. 2.0 Western Montana 04:19 UTC
4. 1.7 4 km WSW of South Hills, Montana 19:08 UTC
5. 2.4 4 km NNW of Helena Valley Northeast, Montana 15:23 UTC
6. 2.3 13 km WSW of Craig, Montana 02:39 UTC
7. 1.7 1 km SE of South Hills, Montana 15:51 UTC
8. 1.6 9 km SSE of Craig, Montana 22:19 UTC
9. 2.1 6 km NE of Helena Valley Northeast, Montana 10:55 UTC
10. 2.3 14 km NNE of Helena Valley Northwest, Montana 22:13 UTC
11. 1.9 30 km NE of Winston, Montana 00:12 UTC
12. 3.3 4 km NNE of Marysville, Montana 03:47 UTC
13. 1.6 Western Montana 19:10 UTC
14. 1.5 16 km SSE of Craig, Montana 18:54 UTC
15. 1.6 16 km S of Craig, Montana 14:58 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 00:46 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

On USGS

• The official USGS event page — the source of record for every value above
• Did you feel it? Report it to USGS — reports go to USGS, not to us
• ShakeMap for this event, when USGS has produced one

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.