QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0ml

Earthquake near Anchorage, AK

No earthquake was likely felt in Anchorage in the 24 hours to 9:25 am AKST (18:25 UTC). The last one was M 3.5, 39 km (24 mi) SSW, at 4:48 pm AKDT on 27 October 2026, estimated intensity II (weak) in town; 98 felt reports to USGS. Every earthquake near Anchorage

This page: a magnitude 4.0 earthquake was recorded 49 km (30 mi) northwest of Anchorage, AK, at 2:32 pm AKST on 16 February 2023 (23:32 UTC), 65 km deep. 279 people have reported feeling it to USGS.

USGS: 2 km SW of Susitna, Alaska

49 km (30 mi) NW of Anchorage, AK

2:32 pm AKST, Feb 16, 2023 · · 65 km deep · released about 15 tons of TNT

Every earthquake near Anchorage Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 78 kmMatanuska-Susitna Borough 99 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
2:32 pm AKST on 16 February 2023 ()
Where
49 km (30 mi) northwest of Anchorage, AK · earthquakes near Anchorage
Magnitude
M 4.0 (ml)
Depth
65 km below the surface
Felt
279 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Anchorage Municipality, 78 km ESE
Nearest mapped fault
Castle Mountain fault, 7 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 1301 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 72 km (45 mi) from the epicentre. In Anchorage, 49 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.

Likely felt in: Big Lake 31 km, intensity II · Willow 36 km, intensity II · Anchorage 49 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× more

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 63 times the energy of this one.

Before 2016, the USGS record lists 24 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 27 km SE of Skwentna, Alaska · 41 km NW of this epicentre
  2. 6.8 4 km NE of Beluga, Alaska · 47 km SSW of this epicentre
  3. 5.8 27 km N of Beluga, Alaska · 30 km WSW of this epicentre
  4. 5.8 20 km ENE of Beluga, Alaska · 34 km SSW of this epicentre
  5. 5.6 11 km NW of Big Lake, Alaska · 23 km ENE 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 61.5269, -150.5443. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 78 km (48 mi) ESE earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 99 km (61 mi) NNE earthquakes near Matanuska-Susitna Borough

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.

  1. 1.5 20 km ESE of Skwentna, Alaska
  2. 1.5 30 km WNW of Willow, Alaska
  3. 1.7 6 km SW of Big Lake, Alaska
  4. 1.8 24 km WSW of Susitna, Alaska
  5. 1.8 12 km SW of Big Lake, Alaska
  6. 1.6 28 km W of Susitna, Alaska
  7. 2.8 5 km NW of Big Lake, Alaska
  8. 2.4 31 km WNW of Willow, Alaska
  9. 1.5 12 km S of Susitna, Alaska
  10. 2.4 22 km WNW of Susitna, Alaska
  11. 1.8 21 km WNW of Susitna, Alaska
  12. 1.7 25 km NNW of Susitna, Alaska
  13. 1.7 14 km NNW of Willow, Alaska
  14. 1.9 24 km ESE of Skwentna, Alaska
  15. 1.5 16 km S 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

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