Earthquake · reviewed by a seismologist
M 1.9md
Earthquake near Afton, WY
No earthquake was likely felt in Afton in the 24 hours to 2:22 pm MST (21:22 UTC). The last one was M 2.3, 14 km (9 mi) W, at 3:44 pm MDT on 19 May 2026, estimated intensity II (weak) in town. Every earthquake near Afton
This page: a magnitude 1.9 earthquake was recorded 3 km (2 mi) south of Afton, WY, at 7:28 pm MDT on 7 September 2023 (01:28 UTC), less than 1 km deep.
USGS: 2 km N of Osmond, Wyoming
- When
- 7:28 pm MDT on 7 September 2023 ()
- Where
- 3 km (2 mi) south of Afton, WY · earthquakes near Afton
- Magnitude
- M 1.9 (md)
- Depth
- -3.4 km below the surface
- Felt
- no reports yet
- Nearest
- Caribou County, 51 km W
- Nearest mapped fault
- Grand Valley fault, under 1 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 1162 days ago
Earthquake alerts for Afton, WY
Get a notification in this browser when USGS records an earthquake near Afton, WY. 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 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 14 km (9 mi) from the epicentre. In Afton, 3 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.
How big was it?
This earthquake released about 18 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 840,000× the energy of this one
- Magna, Utah 2020 M 5.7 600,000× the energy of this one
- Around the size people start to feel M 3.0 53× the energy of this one
- This earthquake M 1.9 about 18 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 5.3 on 2017-09-02 — about 150,000 times the energy of this one.
Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:
- 5.8 4 km SSE of Auburn, Wyoming · 8 km NNW of this epicentre
- 5.3 Southeastern Idaho · 45 km NW of this epicentre
- 5.3 29 km WSW of Freedom, Idaho · 45 km WNW 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 42.7015, -110.9298. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Caribou County, ID | 51 km (32 mi) | W | earthquakes near Caribou County |
| Lincoln County, WY | 56 km (35 mi) | SSE | earthquakes near Lincoln County |
| Bear Lake County, ID | 57 km (35 mi) | SW | earthquakes near Bear Lake County |
| Sublette County, WY | 83 km (52 mi) | E | earthquakes near Sublette County |
| Franklin County, ID | 94 km (58 mi) | SW | earthquakes near Franklin County |
| Bonneville County, ID | 95 km (59 mi) | NW | earthquakes near Bonneville County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
53 earthquakes have been recorded within 50 km since this one.
- 2.0 10 km NNW of Georgetown, Idaho
- 2.3 17 km W of Fairview, Wyoming
- 1.8 17 km WSW of Auburn, Wyoming
- 1.7 18 km WSW of Auburn, Wyoming
- 2.5 21 km E of Soda Springs, Idaho
- 2.6 5 km NNE of Star Valley Ranch, Wyoming
- 2.9 15 km WSW of Freedom, Idaho
- 1.5 14 km E of Soda Springs, Idaho
- 1.6 22 km ENE of Soda Springs, Idaho
- 2.8 22 km NNE of Georgetown, Idaho
- 3.2 20 km W of Fairview, Wyoming
- 2.6 11 km ENE of Georgetown, Idaho
- 3.0 11 km ENE of Georgetown, Idaho
- 1.6 15 km ENE of Bennington, Idaho
- 2.3 3 km NNE of Star Valley Ranch, 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.