QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5ml

Earthquake near Anchor Point, AK

No earthquake was likely felt in Anchor Point in the 24 hours to 4:02 am AKST (13:02 UTC). The last one was M 4.3, 69 km (43 mi) NE, at 2:30 am AKST on 1 November 2026, estimated intensity II (weak) in town; 115 felt reports to USGS. Every earthquake near Anchor Point

This page: a magnitude 3.5 earthquake was recorded 23 km (15 mi) north of Anchor Point, AK, at 10:53 pm AKDT on 31 July 2021 (06:53 UTC), 58 km deep. 25 people have reported feeling it to USGS.

USGS: 4 km NNW of Happy Valley, Alaska

10:53 pm AKDT, Jul 31, 2021 · · 58 km deep · released about 2.7 tons of TNT

Every earthquake near Anchor Point Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Kenai Peninsula Borough 52 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
10:53 pm AKDT on 31 July 2021 ()
Where
23 km (15 mi) north of Anchor Point, AK · earthquakes near Anchor Point
Magnitude
M 3.5 (ml)
Depth
58 km below the surface
Felt
25 reports · strongest reported intensity III
Measured shaking
intensity IV (ShakeMap)
Nearest
Kenai Peninsula Borough, 52 km NW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1857 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 27 km (17 mi) from the epicentre. In Anchor Point, 23 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: Anchor Point 23 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 2.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 63,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,800× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,000× the energy of this one
  4. This earthquake M 3.5 about 2.7 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 5.6× 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 5.3 on 2017-05-07 — about 500 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 16 km WNW of Happy Valley, Alaska · 13 km W of this epicentre
  2. 5.9 13 km N of Fox River, Alaska · 44 km E of this epicentre
  3. 5.8 23 km WNW of Happy Valley, Alaska · 20 km W of this epicentre
  4. 5.6 7 km SE of Fritz Creek, Alaska · 46 km SE of this epicentre
  5. 5.5 13 km NW of Happy Valley, Alaska · 10 km WNW 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 59.9853, -151.7638. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Kenai Peninsula Borough, AK 52 km (33 mi) NW earthquakes near Kenai Peninsula Borough

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

Aftershocks so far

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

  1. 1.5 27 km WSW of Anchor Point, Alaska
  2. 1.6 29 km WNW of Ninilchik, Alaska
  3. 1.7 21 km WNW of Clam Gulch, Alaska
  4. 2.0 Southern Alaska
  5. 2.0 25 km NW of Seldovia, Alaska
  6. 2.2 15 km W of Ninilchik, Alaska
  7. 2.8 9 km SSW of Anchor Point, Alaska
  8. 2.1 16 km WNW of Fox River, Alaska
  9. 1.8 31 km WNW of Clam Gulch, Alaska
  10. 1.6 8 km ENE of Ninilchik, Alaska
  11. 2.0 44 km NW of Ninilchik, Alaska
  12. 1.6 17 km WNW of Anchor Point, Alaska
  13. 2.3 26 km NW of Anchor Point, Alaska
  14. 2.9 10 km NW of Anchor Point, Alaska
  15. 1.5 12 km NNE of Ninilchik, 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.