Earthquake near Seward, AK

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 13 km (8 mi) from the epicentre. In Seward, 47 km away, the estimate is intensity I (not felt). 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 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
3. Around the size people start to feel M 3.0 63× the energy of this one
4. This earthquake M 1.8 about 15 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 3 km SW of Bear Creek, Alaska · 48 km WNW of this epicentre Sep 27, 1949
2. 6.3 37 km SSE of Lowell Point, Alaska · 38 km SW of this epicentre Mar 28, 1964
3. 6.1 25 km WSW of Chenega, Alaska · 13 km ENE of this epicentre Mar 28, 1964
4. 6.0 54 km SE of Lowell Point, Alaska · 32 km SSW of this epicentre Mar 28, 1964
5. 5.9 33 km SSE of Lowell Point, Alaska · 33 km WSW of this epicentre Mar 29, 1964

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 59.9470, -148.6660. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.7 35 km NW of Chenega, Alaska 15:39 UTC
2. 1.9 39 km NW of Chenega, Alaska 02:37 UTC
3. 2.0 34 km ESE of Lowell Point, Alaska 15:41 UTC
4. 2.0 33 km E of Lowell Point, Alaska 09:59 UTC
5. 2.0 30 km NW of Chenega, Alaska 08:58 UTC
6. 2.4 21 km SE of Lowell Point, Alaska 04:56 UTC
7. 2.0 25 km WNW of Chenega, Alaska 04:27 UTC
8. 1.7 42 km NW of Chenega, Alaska 10:46 UTC
9. 2.0 16 km E of Lowell Point, Alaska 14:04 UTC
10. 2.8 31 km SW of Chenega, Alaska 04:46 UTC
11. 2.0 33 km NW of Chenega, Alaska 20:24 UTC
12. 1.9 42 km SW of Chenega, Alaska 13:04 UTC
13. 1.4 36 km E of Bear Creek, Alaska 08:31 UTC
14. 1.7 30 km NW of Chenega, Alaska 08:27 UTC
15. 1.9 31 km NW of Chenega, Alaska 15:50 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:05 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.