QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mw

18 km NE of Valdez, Alaska

· 24 km deep · released about 15 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Chugach Census Area 86 km
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
Magnitude
M 4.0 (mw)
Depth
24 km below the surface
Felt
19 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Chugach Census Area, 86 km S
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1149 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 19 people have reported feeling it to USGS.

How big was it?

This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 32× 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

Epicentre 61.2585, -146.1262. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Chugach Census Area, AK 86 km (53 mi) N of here earthquakes near Chugach Census Area
Copper River Census Area, AK 145 km (90 mi) SW of here earthquakes near Copper River Census Area

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 1.8 43 km SSE of Nelchina, Alaska
  2. 1.9 44 km N of Valdez, Alaska
  3. 1.5 33 km N of Valdez, Alaska
  4. 1.5 50 km N of Valdez, Alaska
  5. 1.7 29 km N of Valdez, Alaska
  6. 3.6 31 km NNW of Valdez, Alaska
  7. 1.7 46 km NNW of Valdez, Alaska
  8. 2.1 41 km NE of Valdez, Alaska
  9. 1.7 36 km NNW of Valdez, Alaska
  10. 1.8 37 km NNW of Valdez, Alaska
  11. 1.5 24 km NW of Valdez, Alaska
  12. 2.3 49 km SSE of Nelchina, Alaska
  13. 2.1 42 km N of Valdez, Alaska
  14. 1.7 36 km NNE of Valdez, Alaska
  15. 1.7 31 km NNW of Valdez, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.3 on 2016-08-19 — it released about 2.8 times the energy of this one.

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

On USGS

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