Earthquake near Helena Valley Northeast, MT

A magnitude 2.3 earthquake was recorded 15 km (9 mi) NNE of Helena Valley Northeast, MT, at 12:32 pm MST on 10 March 2018 (19:32 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

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

How big was it?

This earthquake released about 72 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 210,000× the energy of this one
2. Magna, Utah 2020 M 5.7 150,000× the energy of this one
3. Around the size people start to feel M 3.0 13× the energy of this one
4. This earthquake M 2.3 about 72 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

The largest earthquake within 50 km since 2016 was M 4.3 on 2016-01-30 — about 1,300 times the energy of this one.

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

1. 6.1 The 1935 Helena, Montana Earthquakes (Mainshock) · 31 km SE of this epicentre Oct 19, 1935
2. 5.9 2 km ENE of Helena, Montana · 26 km SSW of this epicentre Oct 12, 1935
3. 5.9 The 1935 Helena, Montana Earthquakes (Largest Aftershock) · 31 km S of this epicentre Oct 31, 1935
4. 5.0 2 km ENE of Helena, Montana · 26 km SSW 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 46.8232, -111.8828. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 1.9 30 km ENE of Helena Valley Northeast, Montana 00:45 UTC
2. 1.8 8 km SSE of Marysville, Montana 04:22 UTC
3. 1.6 3 km SW of Helena Valley Northwest, Montana 23:36 UTC
4. 1.6 1 km SSE of South Hills, Montana 16:47 UTC
5. 1.6 1 km SSE of South Hills, Montana 18:07 UTC
6. 1.7 2 km NNW of Montana City, Montana 17:43 UTC
7. 2.2 6 km W of Helena Valley West Central, Montana 21:40 UTC
8. 2.4 8 km NNE of Helena Valley Northwest, Montana 22:36 UTC
9. 2.9 11 km SW of Winston, Montana 23:10 UTC
10. 1.7 15 km NW of Marysville, Montana 22:47 UTC
11. 2.3 2 km WNW of East Helena, Montana 11:03 UTC
12. 1.8 23 km WSW of Craig, Montana 13:30 UTC
13. 1.6 2 km NW of Montana City, Montana 19:42 UTC
14. 2.0 Western Montana 04:19 UTC
15. 3.1 13 km NNW of Marysville, Montana 06:16 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 04:01 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.