135 km SSE of Perryville, 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 11 km (7 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 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
3. Around the size people start to feel M 3.0 5.6× the energy of this one
4. This earthquake M 2.5 about 170 lb of TNT

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 7.8 on 2020-07-22 — about 89,000,000 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

1. 6.6 104 km SSE of Perryville, Alaska · 32 km N of this epicentre Nov 11, 1938
2. 6.5 94 km ESE of Sand Point, Alaska · 41 km NW of this epicentre Feb 14, 1983
3. 5.9 113 km SE of Sand Point, Alaska · 39 km WSW of this epicentre Jun 7, 1917
4. 5.9 90 km ESE of Sand Point, Alaska · 46 km NW of this epicentre Feb 14, 1983
5. 5.4 139 km SSE of Perryville, Alaska · 32 km E of this epicentre Jan 1, 1991

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 54.7283, -158.6599. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.4 Alaska Peninsula 11:14 UTC
2. 1.6 107 km SE of Sand Point, Alaska 08:35 UTC
3. 2.1 99 km SSE of Perryville, Alaska 21:49 UTC
4. 3.5 95 km ESE of Sand Point, Alaska 21:05 UTC
5. 2.2 south of Alaska 14:19 UTC
6. 2.1 93 km SSE of Perryville, Alaska 21:51 UTC
7. 2.2 99 km SSE of Perryville, Alaska 21:39 UTC
8. 3.4 103 km SSE of Perryville, Alaska 21:32 UTC
9. 2.2 113 km S of Perryville, Alaska 15:25 UTC
10. 2.3 101 km SSE of Perryville, Alaska 13:08 UTC
11. 2.2 132 km SSE of Perryville, Alaska 12:17 UTC
12. 2.2 146 km SSE of Perryville, Alaska 11:16 UTC
13. 2.1 90 km S of Perryville, Alaska 23:06 UTC
14. 2.4 136 km SSE of Perryville, Alaska 22:57 UTC
15. 5.0 134 km SSE of Perryville, Alaska 16:08 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:06 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.