QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7ml

43 km NW of Port Alexander, Alaska

· 9.0 km deep · released about 11 lb of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Sitka City and Borough 73 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 1.7 (ml)
Depth
9.0 km below the surface
Felt
no reports yet
Nearest
Sitka City and Borough, 73 km NNW
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 854 days ago

A magnitude 1.7 earthquake was recorded 43 km NW of Port Alexander, Alaska at 17:04 UTC on 2024-04-27. This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 11 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 89× the energy of this one
  4. This earthquake M 1.7 about 11 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 one earthquake of M5 or more within 50 km:

  1. 5.2 56 km W of Port Alexander, Alaska · 43 km SW 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 56.5516, -135.0802. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Sitka City and Borough, AK 73 km (46 mi) NNW earthquakes near Sitka City and Borough
Prince of Wales-Hyder Census Area, AK 153 km (95 mi) SE earthquakes near Prince of Wales-Hyder Census Area

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

Aftershocks so far

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

  1. 1.6 42 km NW of Port Alexander, Alaska
  2. 2.3 38 km W of Port Alexander, Alaska
  3. 1.7 11 km W of Port Alexander, Alaska
  4. 2.0 40 km NNW of Port Alexander, Alaska
  5. 2.1 46 km NW of Port Alexander, Alaska
  6. 1.5 41 km NW of Port Alexander, Alaska
  7. 1.6 41 km NW of Port Alexander, Alaska
  8. 2.1 42 km NW of Port Alexander, Alaska
  9. 1.6 45 km NW of Port Alexander, Alaska
  10. 1.8 44 km NW of Port Alexander, Alaska
  11. 1.6 43 km NW of Port Alexander, Alaska
  12. 1.5 42 km NNW of Port Alexander, Alaska
  13. 1.7 40 km NNW of Port Alexander, Alaska
  14. 1.9 61 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.

On USGS

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