QuakeIndex

Earthquake · reviewed by a seismologist

M 3.4ml

Earthquake near Susitna North, AK

No earthquake was likely felt in Susitna North in the 24 hours to 3:36 am AKST (12:36 UTC). The last one was M 3.6, 19 km (12 mi) E, at 9:16 am AKDT on 27 October 2026, estimated intensity II (weak) in town; 17 felt reports to USGS. Every earthquake near Susitna North

This page: a magnitude 3.4 earthquake was recorded 15 km (9 mi) south of Susitna North, AK, at 7:31 pm AKDT on 20 September 2018 (03:31 UTC), 43 km deep. 4 people have reported feeling it to USGS.

USGS: 14 km S of Susitna North, Alaska

90 km (56 mi) N of Anchorage, AK

7:31 pm AKDT, Sep 20, 2018 · · 43 km deep · released about 1.9 tons of TNT

Every earthquake near Susitna North Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Matanuska-Susitna Borough 31 kmAnchorage Municipality 99 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
7:31 pm AKDT on 20 September 2018 ()
Where
15 km (9 mi) south of Susitna North, AK · earthquakes near Susitna North
Magnitude
M 3.4 (ml)
Depth
43 km below the surface
Felt
4 reports · strongest reported intensity II
Measured shaking
intensity III (ShakeMap)
Nearest
Matanuska-Susitna Borough, 31 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1185 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 39 km (24 mi) from the epicentre. In Susitna North, 15 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: Susitna North 15 km, intensity II · Willow 33 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 89,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 4,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,800× the energy of this one
  4. This earthquake M 3.4 about 1.9 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 4× 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 4.3 on 2017-08-21 — about 22 times the energy of this one.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.9 23 km NE of Willow, Alaska · 14 km SSE of this epicentre
  2. 5.8 37 km ENE of Susitna North, Alaska · 44 km NE of this epicentre
  3. 5.8 14 km NNE of Fishhook, Alaska · 42 km ESE of this epicentre
  4. 5.4 25 km NNW of Willow, Alaska · 18 km WSW of this epicentre
  5. 5.4 36 km E of Skwentna, Alaska · 47 km WSW 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 62.0302, -149.8273. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Matanuska-Susitna Borough, AK 31 km (19 mi) NNE earthquakes near Matanuska-Susitna Borough
Anchorage Municipality, AK 99 km (62 mi) SSE earthquakes near Anchorage Municipality

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

Aftershocks so far

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

  1. 2.2 8 km N of Meadow Lakes, Alaska
  2. 1.6 10 km E of Willow, Alaska
  3. 2.2 2 km ESE of Houston, Alaska
  4. 2.8 16 km W of Willow, Alaska
  5. 3.8 5 km SSW of Houston, Alaska
  6. 2.0 30 km WSW of Susitna North, Alaska
  7. 1.8 5 km W of Houston, Alaska
  8. 1.6 9 km NNW of Tanaina, Alaska
  9. 1.5 5 km ESE of Talkeetna, Alaska
  10. 1.9 0 km WNW of Meadow Lakes, Alaska
  11. 1.7 12 km SSE of Susitna North, Alaska
  12. 1.5 20 km NNE of Willow, Alaska
  13. 2.1 22 km NW of Willow, Alaska
  14. 1.6 8 km NE of Houston, Alaska
  15. 2.3 16 km N 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.