Earthquake · reviewed by a seismologist
M 1.8ml
Earthquake near Willow, AK
No earthquake was likely felt in Willow in the 24 hours to 10:24 pm AKST (07:24 UTC). The last one was M 2.8, 20 km (12 mi) S, at 6:17 am AKST on 6 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Willow
This page: a magnitude 1.8 earthquake was recorded 47 km (29 mi) northwest of Willow, AK, at 11:58 am AKST on 21 February 2020 (20:58 UTC), 61 km deep.
USGS: 32 km E of Skwentna, Alaska
98 km (61 mi) NNW of Anchorage, AK
- When
- 11:58 am AKST on 21 February 2020 ()
- Where
- 47 km (29 mi) northwest of Willow, AK · earthquakes near Willow
- Magnitude
- M 1.8 (ml)
- Depth
- 61 km below the surface
- Felt
- no reports yet
- Nearest
- Matanuska-Susitna Borough, 73 km ENE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 2447 days ago
Earthquake alerts for Willow, AK
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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 it was probably too small to be felt, even directly above it. In Willow, 47 km away, the estimate is intensity I (not felt). 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 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
- Magna, Utah 2020 M 5.7 710,000× the energy of this one
- Around the size people start to feel M 3.0 63× the energy of this one
- This earthquake M 1.8 about 15 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 5.2 on 2019-09-17 — about 130,000 times the energy of this one.
Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 27 km SE of Skwentna, Alaska · 24 km SSW of this epicentre
- 5.7 19 km E of Skwentna, Alaska · 13 km W of this epicentre
- 5.6 5 km N of Susitna, Alaska · 46 km SSE of this epicentre
- 5.4 25 km NNW of Willow, Alaska · 33 km E of this epicentre
- 5.4 29 km WNW of Susitna, Alaska · 36 km SSW 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 61.9915, -150.7764. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Matanuska-Susitna Borough, AK | 73 km (45 mi) | ENE | earthquakes near Matanuska-Susitna Borough |
| Anchorage Municipality, AK | 120 km (75 mi) | SE | earthquakes near Anchorage Municipality |
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.
- 1.6 31 km SSW of Petersville, Alaska
- 1.8 15 km E of Skwentna, Alaska
- 1.6 9 km WNW of Susitna, Alaska
- 2.0 33 km SW of Trapper Creek, Alaska
- 1.5 28 km SW of Petersville, Alaska
- 1.5 27 km E of Skwentna, Alaska
- 1.9 28 km NNW of Susitna, Alaska
- 1.8 26 km SE of Skwentna, Alaska
- 1.5 26 km WSW of Trapper Creek, Alaska
- 2.2 18 km ENE of Skwentna, Alaska
- 1.7 27 km WSW of Susitna North, Alaska
- 1.5 32 km SW of Petersville, Alaska
- 2.2 30 km SSW of Petersville, Alaska
- 1.6 22 km WNW of Susitna, Alaska
- 1.5 27 km WNW of Susitna, Alaska
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.