QuakeIndex

Earthquake · reviewed by a seismologist

M 5.9mww

69 km WNW of Port Alexander, Alaska

· 11 km deep · released about 11 kilotons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sitka City and Borough 87 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 5.9 (mww)
Depth
11 km below the surface
Felt
591 reports · strongest reported intensity IV
Measured shaking
intensity V (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest
Sitka City and Borough, 87 km NNE
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 274 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 591 people have reported feeling it to USGS.

How big was it?

This earthquake released about 11 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.9 would have released about 32 times as much.

  1. Ridgecrest, California 2019 M 7.1 63× the energy of this one
  2. Loma Prieta, California 1989 M 6.9 32× the energy of this one
  3. Northridge, California 1994 M 6.7 16× the energy of this one
  4. This earthquake M 5.9 about 11 kilotons of TNT
  5. Mineral, Virginia 2011 M 5.8 this one released 1.4× more
  6. Magna, Utah 2020 M 5.7 this one released 2× 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 56.4383, -135.7137. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Sitka City and Borough, AK 87 km (54 mi) SSW of here earthquakes near Sitka City and Borough

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

Aftershocks so far

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

  1. 1.9 58 km SW of Sitka, Alaska
  2. 2.3 38 km W of Port Alexander, Alaska
  3. 2.3 48 km WSW of Port Alexander, Alaska
  4. 2.4 66 km SW of Sitka, Alaska
  5. 2.5 74 km SW of Sitka, Alaska
  6. 2.6 55 km WSW of Sitka, Alaska
  7. 1.6 44 km SW of Sitka, Alaska
  8. 2.3 46 km SW of Sitka, Alaska
  9. 1.9 61 km W of Port Alexander, Alaska
  10. 1.6 45 km NW of Port Alexander, Alaska
  11. 1.9 88 km W of Port Alexander, Alaska
  12. 1.9 61 km WNW of Port Alexander, Alaska
  13. 2.6 61 km WNW of Port Alexander, Alaska
  14. 3.6 62 km WNW of Port Alexander, Alaska
  15. 2.8 60 km WNW of Port Alexander, 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 4.2 on 2020-11-23.

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

On USGS

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