QuakeIndex

Earthquake · reviewed by a seismologist

M 2.5ml

Earthquake near Big Lake, AK

No earthquake was likely felt in Big Lake in the 24 hours to 1:02 pm AKST (22:02 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 2.5 earthquake was recorded in Big Lake, AK, at 4:25 am AKDT on 19 October 2019 (12:25 UTC), 32 km deep. 3 people have reported feeling it to USGS.

USGS: Southern Alaska

33 km (20 mi) N of Anchorage, AK

4:25 am AKDT, Oct 19, 2019 · · 32 km deep · released about 170 lb of TNT

Every earthquake near Big Lake Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 51 kmMatanuska-Susitna Borough 86 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
4:25 am AKDT on 19 October 2019 ()
Where
in Big Lake, AK · earthquakes near Big Lake
Magnitude
M 2.5 (ml)
Depth
32 km below the surface
Felt
3 reports · strongest reported intensity III
Measured shaking
intensity I (ShakeMap)
Nearest
Anchorage Municipality, 51 km SE
Nearest mapped fault
Castle Mountain fault, 9 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 2505 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. 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, Knik-Fairview, Meadow Lakes, Willow, Wasilla, Eagle River.

How big was it?

This earthquake released about 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
  3. Around the size people start to feel M 3.0 5.6× the energy of this one
  4. This earthquake M 2.5 about 170 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 7,900,000 times the energy of this one.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 23 km NE of Willow, Alaska · 45 km NNE of this epicentre
  2. 5.6 11 km NW of Big Lake, Alaska · 13 km NW of this epicentre
  3. 5.6 5 km N of Susitna, Alaska · 32 km WNW of this epicentre
  4. 5.5 2 km ENE of Eagle River, Alaska · 30 km SE of this epicentre
  5. 5.5 9 km E of Susitna, Alaska · 22 km W 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 61.5140, -149.9265. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 51 km (32 mi) SE earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 86 km (54 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

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

  1. 1.8 18 km NW of Fishhook, Alaska
  2. 1.9 3 km NW of Willow, Alaska
  3. 1.7 4 km SSE of Big Lake, Alaska
  4. 2.4 5 km NNE of Big Lake, Alaska
  5. 3.6 4 km NNE of Big Lake, Alaska
  6. 1.5 5 km WSW of Point MacKenzie, Alaska
  7. 1.5 12 km SSW of Willow, Alaska
  8. 1.5 Southern Alaska
  9. 2.4 7 km SE of Big Lake, Alaska
  10. 1.8 3 km SSE of Big Lake, Alaska
  11. 2.1 10 km N of Meadow Lakes, Alaska
  12. 2.3 5 km WNW of Meadow Lakes, Alaska
  13. 2.0 6 km N of Tanaina, Alaska
  14. 2.1 6 km ENE of Houston, Alaska
  15. 1.5 10 km NNE of Meadow Lakes, 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.