Earthquake · automatic estimate, may change
M 2.1ml
Earthquake near Butte, AK
USGS: 25 km SE of Chickaloon, Alaska
- When
- 10:19 pm AKDT on 27 September 2026 ()
- Where
- 48 km (30 mi) ENE of Butte, AK · earthquakes near Butte
- Magnitude
- M 2.1 (ml)
- Depth
- 0.9 km below the surface
- Felt
- 1 report · strongest reported intensity I
- Nearest
- Anchorage Municipality, 79 km SW
- Nearest mapped fault
- Castle Mountain fault, 25 km from its surface trace — near is not the same as on
- Status
- Automatic — a machine’s first estimate, which may change
USGS · last changed by USGS · we first saw it 5 days ago
A magnitude 2.1 earthquake was recorded 48 km (30 mi) ENE of Butte, AK, at 10:19 pm AKDT on 27 September 2026 (06:19 UTC). 1 person has reported feeling it to USGS. This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
How big was it?
This earthquake released about 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
- Magna, Utah 2020 M 5.7 250,000× the energy of this one
- Around the size people start to feel M 3.0 22× the energy of this one
- This earthquake M 2.1 about 43 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 4.6 on 2018-01-27 — about 5,600 times the energy of this one.
Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:
- 6.8 31 km SSW of Glacier View, Alaska · 21 km ESE of this epicentre
- 6.4 23 km S of Glacier View, Alaska · 25 km E of this epicentre
- 6.4 37 km SSE of Glacier View, Alaska · 42 km ESE of this epicentre
- 5.9 15 km N of Glacier View, Alaska · 42 km NNE of this epicentre
- 5.9 42 km S of Glacier View, Alaska · 37 km SE 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 61.6300, -148.1360. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Anchorage Municipality, AK | 79 km (49 mi) | SW | earthquakes near Anchorage Municipality |
| Matanuska-Susitna Borough, AK | 101 km (62 mi) | NW | earthquakes near Matanuska-Susitna Borough |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
2 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.
Revisions
USGS refines a solution as more stations report. Every change we have seen is listed here.
| What changed | From | To | When |
|---|---|---|---|
| reported intensity | not reported | 1 | |
| felt reports | not reported | 1 | |
| magnitude | 1.9 | 2.1 | |
| location | 28 km SE of Chickaloon, Alaska | 25 km SE of Chickaloon, Alaska | |
| longitude | -148.12 | -148.14 | |
| latitude | 61.6 | 61.63 | |
| depth | 14.2 | 0.9 | |
| magnitude | 1.8 | 1.9 |
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.