QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

Earthquake near Big Lake, AK

No earthquake was likely felt in Big Lake in the 24 hours to 2:29 pm AKST (23:29 UTC). The last one was M 2.8, 6 km (4 mi) NW, at 6:17 am AKST on 6 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Big Lake

This page: a magnitude 1.5 earthquake was recorded 14 km (9 mi) west of Big Lake, AK, at 4:22 am AKDT on 18 May 2023 (12:22 UTC), 39 km deep.

USGS: 14 km W of Big Lake, Alaska

37 km (23 mi) NNW of Anchorage, AK

4:22 am AKDT, May 18, 2023 · · 39 km deep · released about 5.4 lb of TNT

Every earthquake near Big Lake Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 62 kmMatanuska-Susitna Borough 92 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
4:22 am AKDT on 18 May 2023 ()
Where
14 km (9 mi) west of Big Lake, AK · earthquakes near Big Lake
Magnitude
M 1.5 (ml)
Depth
39 km below the surface
Felt
no reports yet
Nearest
Anchorage Municipality, 62 km SE
Nearest mapped fault
Castle Mountain fault, 3 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 1273 days ago

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 Big Lake, 14 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.

Earthquakes near other towns within 30 km: Houston, Willow.

How big was it?

This earthquake released about 5.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 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 7.1 on 2018-11-30 — about 250,000,000 times the energy of this one.

Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.8 27 km N of Beluga, Alaska · 45 km WSW of this epicentre
  2. 5.8 20 km ENE of Beluga, Alaska · 42 km SW of this epicentre
  3. 5.6 11 km NW of Big Lake, Alaska · 10 km NNE of this epicentre
  4. 5.6 5 km N of Susitna, Alaska · 18 km WNW of this epicentre
  5. 5.5 2 km ENE of Eagle River, Alaska · 42 km ESE 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 61.5077, -150.2217. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 62 km (39 mi) SE earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 92 km (57 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

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

  1. 2.5 3 km ESE of Big Lake, Alaska
  2. 1.5 6 km E of Big Lake, Alaska
  3. 3.1 6 km ESE of Big Lake, Alaska
  4. 1.8 12 km NW of Susitna, Alaska
  5. 2.0 9 km WNW of Anchorage, Alaska
  6. 1.6 6 km ENE of Susitna, Alaska
  7. 1.8 Southern Alaska
  8. 1.6 Southern Alaska
  9. 1.6 12 km WSW of Point MacKenzie, Alaska
  10. 1.6 Southern Alaska
  11. 1.5 11 km SW of Point MacKenzie, Alaska
  12. 3.6 11 km SW of Point MacKenzie, Alaska
  13. 1.8 11 km SW of Point MacKenzie, Alaska
  14. 1.5 2 km ESE of Big Lake, Alaska
  15. 2.8 2 km ESE 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.