QuakeIndex

Earthquake · reviewed by a seismologist

M 3.0ml

Earthquake near Seward, AK

No earthquake was likely felt in Seward in the 24 hours to 3:15 pm AKST (00:15 UTC). The last one was M 4.3, 83 km (52 mi) W, at 2:30 am AKST on 1 November 2026, estimated intensity II (weak) in town; 115 felt reports to USGS. Every earthquake near Seward

This page: a magnitude 3.0 earthquake was recorded 18 km (11 mi) southwest of Seward, AK, at 12:07 pm AKDT on 23 July 2020 (20:07 UTC), 17 km deep. 10 people have reported feeling it to USGS.

USGS: 15 km SW of Lowell Point, Alaska

12:07 pm AKDT, Jul 23, 2020 · · 17 km deep · released about 950 lb of TNT

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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
12:07 pm AKDT on 23 July 2020 ()
Where
18 km (11 mi) southwest of Seward, AK · earthquakes near Seward
Magnitude
M 3.0 (ml)
Depth
17 km below the surface
Felt
10 reports · strongest reported intensity III
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2232 days ago

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 33 km (21 mi) from the epicentre. In Seward, 18 km away, the estimate is intensity II (weak). 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.

Likely felt in: Seward 18 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 350,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
  3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
  4. This earthquake M 3.0 about 950 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 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.6 3 km SW of Bear Creek, Alaska · 22 km NNE of this epicentre
  2. 6.3 37 km SSE of Lowell Point, Alaska · 34 km SE of this epicentre
  3. 5.9 33 km SSE of Lowell Point, Alaska · 32 km SE of this epicentre
  4. 5.8 33 km ESE of Bear Creek, Alaska · 49 km ENE of this epicentre
  5. 5.6 52 km S of Lowell Point, Alaska · 42 km S of this epicentre

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 59.9719, -149.6392. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.0 60 km S of Lowell Point, Alaska
  2. 1.7 Kenai Peninsula, Alaska
  3. 1.6 34 km SSW of Cooper Landing, Alaska
  4. 1.5 41 km WSW of Lowell Point, Alaska
  5. 2.7 47 km ESE of Fox River, Alaska
  6. 2.2 46 km ESE of Fox River, Alaska
  7. 1.6 25 km WNW of Seward, Alaska
  8. 1.6 12 km ESE of Bear Creek, Alaska
  9. 1.8 21 km SSE of Cooper Landing, Alaska
  10. 1.5 29 km SSW of Cooper Landing, Alaska
  11. 1.5 18 km E of Lowell Point, Alaska
  12. 1.6 21 km SW of Lowell Point, Alaska
  13. 1.8 Kenai Peninsula, Alaska
  14. 2.4 15 km ESE of Lowell Point, Alaska
  15. 1.5 13 km E of Lowell Point, Alaska

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

On USGS

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