QuakeIndex

Earthquake · reviewed by a seismologist

M 2.1ml

Earthquake near Willow, AK

No earthquake was likely felt in Willow in the 24 hours to 1:25 am AKST (10:25 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 2.1 earthquake was recorded 23 km (14 mi) northwest of Willow, AK, at 8:09 am AKST on 20 November 2018 (17:09 UTC), 15 km deep.

USGS: 22 km NW of Willow, Alaska

80 km (50 mi) NNW of Anchorage, AK

8:09 am AKST, Nov 20, 2018 · · 15 km deep · released about 43 lb of TNT

Every earthquake near Willow Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Matanuska-Susitna Borough 58 kmAnchorage Municipality 98 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
8:09 am AKST on 20 November 2018 ()
Where
23 km (14 mi) northwest of Willow, AK · earthquakes near Willow
Magnitude
M 2.1 (ml)
Depth
15 km below the surface
Felt
no reports yet
Nearest
Matanuska-Susitna Borough, 58 km NE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1184 days ago

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. In Willow, 23 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 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.

  1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
  3. Around the size people start to feel M 3.0 22× the energy of this one
  4. 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 4.5 on 2016-01-18 — about 4,000 times the energy of this one.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 27 km SE of Skwentna, Alaska · 39 km WSW of this epicentre
  2. 5.9 23 km NE of Willow, Alaska · 30 km E of this epicentre
  3. 5.7 19 km E of Skwentna, Alaska · 38 km WNW of this epicentre
  4. 5.6 11 km NW of Big Lake, Alaska · 38 km SSE of this epicentre
  5. 5.6 5 km N 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 61.9071, -150.3119. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 58 km (36 mi) NE earthquakes near Matanuska-Susitna Borough
Anchorage Municipality, AK 98 km (61 mi) SE earthquakes near Anchorage Municipality

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

34 earthquakes have been recorded within 50 km since this one.

  1. 2.8 3 km SSE of Big Lake, Alaska
  2. 3.1 2 km SSW of Big Lake, Alaska
  3. 2.7 1 km S of Big Lake, Alaska
  4. 2.8 16 km W of Willow, Alaska
  5. 3.4 7 km WSW of Big Lake, Alaska
  6. 3.0 2 km NE of Big Lake, Alaska
  7. 2.2 2 km E of Big Lake, Alaska
  8. 3.2 2 km SSE of Big Lake, Alaska
  9. 3.2 5 km SW of Big Lake, Alaska
  10. 3.3 1 km SSE of Big Lake, Alaska
  11. 3.2 1 km ESE of Big Lake, Alaska
  12. 2.9 1 km SE of Big Lake, Alaska
  13. 3.8 5 km SSW of Houston, Alaska
  14. 3.1 2 km ESE of Big Lake, Alaska
  15. 3.7 2 km SSW of Big Lake, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.