QuakeIndex

Earthquake · reviewed by a seismologist

M 3.6ml

Earthquake near Big Lake, AK

No earthquake was likely felt in Big Lake in the 24 hours to 5:05 am AKST (14:05 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 3.6 earthquake was recorded 4 km (3 mi) north-northeast of Big Lake, AK, at 10:17 pm AKST on 6 November 2019 (07:17 UTC), 46 km deep. 214 people have reported feeling it to USGS.

USGS: 4 km NNE of Big Lake, Alaska

37 km (23 mi) N of Anchorage, AK

10:17 pm AKST, Nov 6, 2019 · · 46 km deep · released about 3.8 tons of TNT

Every earthquake near Big Lake Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Anchorage Municipality 54 kmMatanuska-Susitna Borough 82 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
10:17 pm AKST on 6 November 2019 ()
Where
4 km (3 mi) north-northeast of Big Lake, AK · earthquakes near Big Lake
Magnitude
M 3.6 (ml)
Depth
46 km below the surface
Felt
214 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
Nearest
Anchorage Municipality, 54 km SE
Nearest mapped fault
Castle Mountain fault, 5 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 2477 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, people at rest would likely notice it out to about 52 km (32 mi) from the epicentre. In Big Lake, 4 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 4 km, intensity II · Knik-Fairview 17 km, intensity II · Willow 22 km, intensity II · Tanaina 27 km, intensity II · Eagle River 32 km, intensity II · Anchorage 37 km, intensity II · Fishhook 42 km, intensity II · Palmer 43 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 3.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 45,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 1,400× the energy of this one
  4. This earthquake M 3.6 about 3.8 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 7.9× 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 7.1 on 2018-11-30 — about 180,000 times the energy of this one.

Before 2016, the USGS record lists 21 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 23 km NE of Willow, Alaska · 41 km NNE of this epicentre
  2. 5.6 11 km NW of Big Lake, Alaska · 11 km WNW of this epicentre
  3. 5.6 5 km N of Susitna, Alaska · 32 km W of this epicentre
  4. 5.5 2 km ENE of Eagle River, Alaska · 33 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 61.5539, -149.9163. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Anchorage Municipality, AK 54 km (34 mi) SE earthquakes near Anchorage Municipality
Matanuska-Susitna Borough, AK 82 km (51 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

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

  1. 1.7 6 km WNW of Point MacKenzie, Alaska
  2. 1.6 5 km ESE of Houston, Alaska
  3. 1.6 8 km SSW of Big Lake, Alaska
  4. 2.0 8 km E of Elmendorf Air Force Base, Alaska
  5. 1.9 15 km W of Anchorage, Alaska
  6. 1.5 4 km WNW of Houston, Alaska
  7. 1.5 1 km SSE of Big Lake, Alaska
  8. 1.7 4 km ESE of Big Lake, Alaska
  9. 2.8 2 km NNW of Houston, Alaska
  10. 2.0 8 km S of Big Lake, Alaska
  11. 1.6 9 km NNE of Willow, Alaska
  12. 2.9 0 km ENE of Houston, Alaska
  13. 1.6 3 km NW of Knik, Alaska
  14. 1.8 1 km SE of Big Lake, Alaska
  15. 1.5 1 km WSW of Houston, 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.