QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8ml

84 km SE of Port Graham, Alaska

· 51 km deep · released about 15 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
Magnitude
M 1.8 (ml)
Depth
51 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1143 days ago

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

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.

Where

Epicentre 58.8620, -150.7141. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.8 111 km SSE of Port Graham, Alaska
  2. 1.8 105 km SSE of Port Graham, Alaska
  3. 2.3 82 km SSE of Halibut Cove, Alaska
  4. 2.0 63 km SE of Port Graham, Alaska
  5. 2.5 45 km SE of Halibut Cove, Alaska
  6. 2.6 94 km SSE of Halibut Cove, Alaska
  7. 2.0 89 km SE of Port Graham, Alaska
  8. 2.4 72 km SE of Halibut Cove, Alaska
  9. 4.7 110 km SSE of Port Graham, Alaska
  10. 3.3 114 km SSE of Halibut Cove, Alaska
  11. 1.5 102 km SSE of Port Graham, Alaska
  12. 1.9 76 km SSE of Halibut Cove, Alaska
  13. 2.4 102 km NE of Ouzinkie, Alaska
  14. 1.5 56 km SE of Halibut Cove, Alaska
  15. 1.8 58 km SE of Port Graham, 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.