130 km SE of Perryville, Alaska

2020-09-25 05:57 UTC · 27 km deep · released about 340 tons of TNT

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: 2020-09-25 05:57 UTC
Magnitude: M 4.9 (ml)
Depth: 27 km below the surface
Felt: 1 report · strongest reported intensity II
Measured shaking: intensity III (ShakeMap)
USGS impact alert: green
Tsunami: USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status: Reviewed by a seismologist

USGS · last changed by USGS 1886 days ago · we first saw it 1886 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 340 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.

Northridge, California 1994 M 6.7 500× the energy of this one
Mineral, Virginia 2011 M 5.8 22× the energy of this one
Magna, Utah 2020 M 5.7 16× the energy of this one
This earthquake M 4.9 about 340 tons of TNT
Around the size people start to feel M 3.0 this one released 710× 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.

Where

Map loads when it scrolls into view

Epicentre 55.0354, -157.7635. Map © OpenStreetMap contributors.

Aftershocks so far

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

2.6 118 km SE of Perryville, Alaska 16:57 UTC
3.7 90 km SE of Perryville, Alaska 01:16 UTC
3.0 93 km SE of Perryville, Alaska 02:45 UTC
2.4 94 km SE of Perryville, Alaska 12:19 UTC
2.3 99 km SE of Perryville, Alaska 18:00 UTC
3.4 113 km SE of Perryville, Alaska 00:57 UTC
2.5 102 km SE of Perryville, Alaska 21:43 UTC
3.7 114 km SE of Perryville, Alaska 20:37 UTC
3.1 101 km SE of Perryville, Alaska 22:41 UTC
2.4 105 km SSE of Perryville, Alaska 01:49 UTC
2.6 138 km SE of Perryville, Alaska 15:51 UTC
2.4 147 km SE of Perryville, Alaska 12:28 UTC
2.8 Alaska Peninsula 00:47 UTC
2.5 138 km SSE of Perryville, Alaska 03:59 UTC
4.2 109 km SE of Perryville, Alaska 21:17 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 13:17 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 5.4 on 2020-08-08 — it released about 5.6 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

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.