QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

Earthquake near Big Lake, AK

No earthquake was likely felt in Big Lake in the 24 hours to 4:22 am AKST (13:22 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 1.9 earthquake was recorded 40 km (25 mi) west-northwest of Big Lake, AK, at 8:27 pm AKDT on 23 August 2019 (04:27 UTC), 11 km deep.

USGS: 15 km NNW of Susitna, Alaska

64 km (40 mi) NW of Anchorage, AK

8:27 pm AKDT, Aug 23, 2019 · · 11 km deep · released about 21 lb of TNT

Every earthquake near Big Lake Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Matanuska-Susitna Borough 89 kmAnchorage Municipality 91 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
8:27 pm AKDT on 23 August 2019 ()
Where
40 km (25 mi) west-northwest of Big Lake, AK · earthquakes near Big Lake
Magnitude
M 1.9 (ml)
Depth
11 km below the surface
Felt
no reports yet
Nearest
Matanuska-Susitna Borough, 89 km NE
Nearest mapped fault
Castle Mountain fault, 23 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 2611 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 Big Lake, 40 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 21 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 710,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 500,000× the energy of this one
  3. Around the size people start to feel M 3.0 45× the energy of this one
  4. This earthquake M 1.9 about 21 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 2018-10-15 — about 7,900 times the energy of this one.

Before 2016, the USGS record lists 22 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 27 km SE of Skwentna, Alaska · 25 km NW of this epicentre
  2. 5.8 27 km N of Beluga, Alaska · 38 km SSW of this epicentre
  3. 5.8 20 km ENE of Beluga, Alaska · 49 km S of this epicentre
  4. 5.7 19 km E of Skwentna, Alaska · 40 km NNW of this epicentre
  5. 5.6 11 km NW of Big Lake, Alaska · 29 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 61.6733, -150.6417. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 89 km (55 mi) NE earthquakes near Matanuska-Susitna Borough
Anchorage Municipality, AK 91 km (57 mi) SE earthquakes near Anchorage Municipality

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

Aftershocks so far

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

  1. 2.8 14 km SW of Willow, Alaska
  2. 1.8 9 km SW of Willow, Alaska
  3. 3.1 34 km WSW of Susitna North, Alaska
  4. 2.2 9 km WSW of Susitna, Alaska
  5. 1.7 11 km WNW of Willow, Alaska
  6. 1.8 25 km WNW of Susitna, Alaska
  7. 1.5 13 km NNE of Susitna, Alaska
  8. 1.8 22 km ESE of Skwentna, Alaska
  9. 2.0 16 km NNE of Susitna, Alaska
  10. 1.5 28 km WSW of Susitna, Alaska
  11. 1.6 10 km NW of Willow, Alaska
  12. 1.6 8 km WNW of Point MacKenzie, Alaska
  13. 1.6 26 km ENE of Skwentna, Alaska
  14. 1.6 10 km NW of Willow, Alaska
  15. 1.8 19 km WSW of Point MacKenzie, 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.