127 km S of False Pass, Alaska

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

How big was it?

This earthquake released about 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 710× the energy of this one
2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
3. Magna, Utah 2020 M 5.7 22× the energy of this one
4. This earthquake M 4.8 about 240 tons of TNT
5. Around the size people start to feel M 3.0 this one released 500× 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 5.9 on 2016-10-27 — about 45 times the energy of this one.

Before 2016, the USGS record lists 65 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 146 km ESE of Akutan, Alaska · 21 km S of this epicentre Apr 1, 1946
2. 6.2 Unimak Island region, Alaska · 16 km WNW of this epicentre Oct 14, 1933
3. 6.2 102 km SSW of False Pass, Alaska · 36 km NNW of this epicentre Aug 20, 1939
4. 6.2 136 km SE of Akutan, Alaska · 39 km SW of this epicentre Apr 1, 1946
5. 6.2 136 km S of False Pass, Alaska · 9 km SSW of this epicentre Apr 2, 1946

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 53.7226, -163.7238. Map © OpenStreetMap contributors.

Aftershocks so far

No further earthquakes have been recorded within 50 km since this one.

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:05 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

Revisions

USGS refines a solution as more stations report. Every change we have seen is listed here.

On USGS

• The official USGS event page — the source of record for every value above
• Did you feel it? Report it to USGS — reports go to USGS, not to us
• ShakeMap for this event, when USGS has produced one

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.