QuakeIndex

Earthquake · reviewed by a seismologist

M 4.6mb

Earthquake near Unalaska, AK

No earthquake was likely felt in Unalaska in the 24 hours to 6:41 pm AKST (03:41 UTC). The last one was M 4.4, 117 km (72 mi) ESE, at 3:00 pm AKST on 11 November 2026, estimated intensity II (weak) in town. Every earthquake near Unalaska

This page: a magnitude 4.6 earthquake was recorded 17 km (10 mi) east of Unalaska, AK, at 9:13 am AKST on 15 November 2018 (18:13 UTC), 84 km deep. 3 people have reported feeling it to USGS.

USGS: 16 km E of Unalaska, Alaska

9:13 am AKST, Nov 15, 2018 · · 84 km deep · released about 120 tons of TNT

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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
9:13 am AKST on 15 November 2018 ()
Where
17 km (10 mi) east of Unalaska, AK · earthquakes near Unalaska
Magnitude
M 4.6 (mb)
Depth
84 km below the surface
Felt
3 reports · strongest reported intensity III
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1559 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 123 km (76 mi) from the epicentre. In Unalaska, 17 km away, the estimate is intensity III (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: Unalaska 17 km, intensity III · Akutan 45 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 120 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.6 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,400× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 63× the energy of this one
  3. Magna, Utah 2020 M 5.7 45× the energy of this one
  4. This earthquake M 4.6 about 120 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 250× 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 (31 mi) since our catalogue begins in 2016. The previous largest was M 4.0 on 2016-08-29.

Before 2016, the USGS record lists 18 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.1 39 km S of Akutan, Alaska · 35 km ESE of this epicentre
  2. 6.2 57 km SE of Unalaska, Alaska · 45 km SE of this epicentre
  3. 6.2 36 km ESE of Unalaska, Alaska · 22 km SE of this epicentre
  4. 6.2 53 km S of Akutan, Alaska · 48 km ESE of this epicentre
  5. 6.0 59 km S of Akutan, Alaska · 47 km SE 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 53.8605, -166.2834. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.6 40 km S of Akutan, Alaska
  2. 2.2 12 km S of Unalaska, Alaska
  3. 3.0 46 km S of Akutan, Alaska
  4. 2.6 19 km ENE of Dutch Harbor, Alaska
  5. 2.5 53 km SE of Unalaska, Alaska
  6. 3.6 5 km SW of Akutan, Alaska
  7. 2.0 55 km SE of Unalaska, Alaska
  8. 2.8 42 km S of Unalaska, Alaska
  9. 1.7 6 km N of Dutch Harbor, Alaska
  10. 2.0 7 km W of Dutch Harbor, Alaska
  11. 1.5 9 km W of Dutch Harbor, Alaska
  12. 3.6 30 km W of Akutan, Alaska
  13. 3.5 45 km SE of Unalaska, Alaska
  14. 2.8 51 km S of Akutan, Alaska
  15. 2.5 18 km SSW of Unalaska, 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.