245 km SSE of False Pass, Alaska

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 51 km (32 mi) from the epicentre. 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.

How big was it?

This earthquake released about 1.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 130,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 5,600× the energy of this one
3. Magna, Utah 2020 M 5.7 4,000× the energy of this one
4. This earthquake M 3.3 about 1.3 tons of TNT
5. Around the size people start to feel M 3.0 this one released 2.8× 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 4.4 on 2019-10-26 — about 45 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

1. 6.3 226 km SSE of False Pass, Alaska · 21 km N of this epicentre Feb 6, 1965
2. 6.3 210 km S of King Cove, Alaska · 44 km NNE of this epicentre Feb 6, 1965
3. 5.8 280 km SSE of False Pass, Alaska · 37 km SE of this epicentre Aug 12, 1966
4. 5.6 203 km SSE of False Pass, Alaska · 48 km NW of this epicentre Jun 20, 1969
5. 5.4 221 km SSE of False Pass, Alaska · 31 km NNE of this epicentre Jul 2, 1993

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 52.8128, -161.9898. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.2 240 km SSE of False Pass, Alaska 12:58 UTC
2. 5.0 244 km SSE of False Pass, Alaska 21:06 UTC
3. 3.5 210 km SSE of False Pass, Alaska 23:28 UTC
4. 2.7 219 km S of King Cove, Alaska 17:44 UTC
5. 2.8 233 km SSE of King Cove, Alaska 02:23 UTC
6. 2.9 204 km SSE of False Pass, Alaska 02:01 UTC
7. 3.5 225 km SSE of False Pass, Alaska 17:22 UTC
8. 3.2 227 km SSE of False Pass, Alaska 17:15 UTC
9. 2.7 217 km SSE of False Pass, Alaska 12:16 UTC
10. 3.1 236 km SSE of False Pass, Alaska 06:26 UTC
11. 2.6 219 km S of King Cove, Alaska 09:39 UTC
12. 2.8 212 km S of King Cove, Alaska 10:46 UTC
13. 3.0 219 km SSE of King Cove, Alaska 10:01 UTC
14. 4.2 225 km SSE of False Pass, Alaska 02:58 UTC
15. 2.3 220 km SSE of King Cove, Alaska 12:21 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:05 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

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.