Earthquake · reviewed by a seismologist
M 1.6ml
51 km SE of Mammoth, Wyoming
Yes. A magnitude 1.6 earthquake was recorded 51 km SE of Mammoth, Wyoming, at 9:04 am MDT on 21 August 2025 (15:04 UTC), 5.5 km deep.
- When
- Magnitude
- M 1.6 (ml)
- Depth
- 5.5 km below the surface
- Felt
- no reports yet
- Nearest
- Park County, 59 km E
- Nearest mapped fault
- Eagle Bay fault, 10 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 447 days ago
Earthquake alerts for West Yellowstone, MT
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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 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 9 km (6 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 7.1 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.
- Mineral, Virginia 2011 M 5.8 2,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,500,000× the energy of this one
- Around the size people start to feel M 3.0 130× the energy of this one
- This earthquake M 1.6 about 7.1 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 4.2 on 2022-05-11 — about 9,100 times the energy of this one.
Before 2016, the USGS record lists 11 earthquakes of M5 or more within 50 km; the five largest:
- 6.5 14 km N of Madison Junction, Wyoming · 49 km WNW of this epicentre
- 6.3 22 km SW of Mammoth, Wyoming · 49 km WNW of this epicentre
- 6.0 21 km E of West Yellowstone, Montana · 41 km W of this epicentre
- 5.9 26 km SSE of Mammoth, Wyoming · 28 km NW of this epicentre
- 5.7 13 km SSW of Mammoth, Wyoming · 45 km NW of this epicentre
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 44.5962, -110.3237. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Park County, WY | 59 km (37 mi) | E | earthquakes near Park County |
| Teton County, WY | 61 km (38 mi) | S | earthquakes near Teton County |
| Park County, MT | 98 km (61 mi) | N | earthquakes near Park County |
| Fremont County, ID | 101 km (63 mi) | WSW | earthquakes near Fremont County |
| Teton County, ID | 117 km (73 mi) | SW | earthquakes near Teton County |
| Gallatin County, MT | 122 km (76 mi) | NNW | earthquakes near Gallatin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 1.7 33 km E of West Yellowstone, Montana
- 2.5 33 km E of West Yellowstone, Montana
- 1.5 23 km SSW of Mammoth, Wyoming
- 1.7 23 km SSW of Mammoth, Wyoming
- 1.9 23 km SSW of Mammoth, Wyoming
- 1.6 23 km SSW of Mammoth, Wyoming
- 2.1 23 km SSW of Mammoth, Wyoming
- 1.8 23 km SSW of Mammoth, Wyoming
- 1.6 22 km SSW of Mammoth, Wyoming
- 2.3 23 km SSW of Mammoth, Wyoming
- 1.6 23 km SSW of Mammoth, Wyoming
- 2.5 23 km SSW of Mammoth, Wyoming
- 2.2 23 km SSW of Mammoth, Wyoming
- 3.7 22 km SSW of Mammoth, Wyoming
- 2.7 22 km SSW of Mammoth, Wyoming
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.