mining explosion · reviewed by a seismologist
M 3.0ml
Earthquake near Mountain Iron, MN
No earthquake was likely felt in Mountain Iron in the 24 hours to 2:21 pm CST (20:21 UTC). The last one was M 2.8, 12 km (8 mi) NNE, at 12:23 pm CDT on 2 July 2026, estimated intensity III (weak) in town. Every earthquake near Mountain Iron
No: USGS classifies this as a mining explosion, not an earthquake. A magnitude 3.0 mining explosion was recorded 5 km (3 mi) north-northeast of Mountain Iron, MN, at 12:23 pm CDT on 10 September 2021 (17:23 UTC), less than 1 km deep.
USGS: 5 km NNE of Mountain Iron, Minnesota
- When
- 12:23 pm CDT on 10 September 2021 ()
- Where
- 5 km (3 mi) north-northeast of Mountain Iron, MN · earthquakes near Mountain Iron
- Magnitude
- M 3.0 (ml)
- Depth
- 0.0 km below the surface
- Felt
- no reports yet
- Nearest
- St. Louis County, 7 km E
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1815 days ago
Earthquake alerts for Mountain Iron, MN
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 73 km (45 mi) from the epicentre. In Mountain Iron, 5 km away, the estimate is intensity III (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: Parkville, Virginia, Eveleth, Gilbert, Chisholm, Aurora.
USGS catalogues this as mining explosion, not an earthquake.
How big was it?
This earthquake released about 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 350,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
- Magna, Utah 2020 M 5.7 11,000× the energy of this one
- This earthquake M 3.0 about 950 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 since 1900 lists no earthquake of M5 or more within 50 km.
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 47.5768, -92.6040. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| St. Louis County, MN | 7 km (4 mi) | E | earthquakes near St. Louis County |
| Itasca County, MN | 76 km (47 mi) | W | earthquakes near Itasca County |
| Lake County, MN | 90 km (56 mi) | E | earthquakes near Lake County |
| Carlton County, MN | 108 km (67 mi) | S | earthquakes near Carlton County |
| Koochiching County, MN | 115 km (72 mi) | NW | earthquakes near Koochiching County |
| Aitkin County, MN | 125 km (77 mi) | SSW | earthquakes near Aitkin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
33 earthquakes have been recorded within 50 km since this one.
- 2.8 11 km NNE of Parkville, Minnesota
- 2.5 5 km NW of Biwabik, Minnesota
- 2.6 6 km NW of Mountain Iron, Minnesota
- 2.7 4 km NW of Leonidas, Minnesota
- 2.6 4 km NNE of Virginia, Minnesota
- 2.8 3 km ENE of Virginia, Minnesota
- 2.5 3 km NNW of Parkville, Minnesota
- 2.7 2 km NNE of Kinney, Minnesota
- 2.9 7 km S of Buhl, Minnesota
- 2.9 6 km NNE of Kinney, Minnesota
- 2.7 4 km NNW of Buhl, Minnesota
- 2.6 4 km NNW of Mountain Iron, Minnesota
- 3.0 3 km N of Kinney, Minnesota
- 2.8 0 km SSE of Parkville, Minnesota
- 2.9 2 km N of Parkville, Minnesota
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . 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.