Earthquake · reviewed by a seismologist
M 3.6ml
27 km SSE of Melstone, Montana
Yes. A magnitude 3.6 earthquake was recorded 27 km SSE of Melstone, Montana, 89 km (55 mi) NE of Billings, MT, at 5:44 am MDT on 6 July 2021 (11:44 UTC), 10 km deep. 23 people have reported feeling it to USGS.
89 km (55 mi) NE of Billings, MT
- When
- Montana today
- every earthquake in Montana in the last 24 hours
- Magnitude
- M 3.6 (ml)
- Depth
- 10 km below the surface
- Felt
- 23 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- USGS impact alert
- green
- Nearest
- Treasure County, 40 km ESE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1888 days ago
Earthquake alerts for Roundup, MT
Get a notification in this browser when USGS records an earthquake near Roundup, MT. No account or email needed.
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 69 km (43 mi) from the epicentre. 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.
How big was it?
This earthquake released about 3.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 45,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 2,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,400× the energy of this one
- This earthquake M 3.6 about 3.8 tons of TNT
- Around the size people start to feel M 3.0 this one released 7.9× more
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 46.3679, -107.7505. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Treasure County, MT | 40 km (25 mi) | ESE | earthquakes near Treasure County |
| Musselshell County, MT | 55 km (34 mi) | WNW | earthquakes near Musselshell County |
| Yellowstone County, MT | 63 km (39 mi) | SW | earthquakes near Yellowstone County |
| Rosebud County, MT | 86 km (53 mi) | ESE | earthquakes near Rosebud County |
| Petroleum County, MT | 93 km (58 mi) | NNW | earthquakes near Petroleum County |
| Big Horn County, MT | 108 km (67 mi) | S | earthquakes near Big Horn County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
No further earthquakes have been recorded within 50 km since this one.
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.