QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9ml

40 km ESE of Port Graham, Alaska

· 31 km deep · released about 21 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 1.9 (ml)
Depth
31 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2384 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 21 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 710,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 500,000× the energy of this one
  3. Around the size people start to feel M 3.0 45× the energy of this one
  4. This earthquake M 1.9 about 21 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 59.1832, -151.2077. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.6 7 km SW of Halibut Cove, Alaska
  2. 1.5 3 km NW of Seldovia Village, Alaska
  3. 1.6 9 km S of Halibut Cove, Alaska
  4. 2.5 16 km ESE of Seldovia Village, Alaska
  5. 1.6 13 km SW of Halibut Cove, Alaska
  6. 1.9 11 km SSW of Halibut Cove, Alaska
  7. 2.1 13 km SSW of Halibut Cove, Alaska
  8. 2.1 68 km SE of Port Graham, Alaska
  9. 2.4 28 km SE of Port Graham, Alaska
  10. 2.0 16 km ESE of Halibut Cove, Alaska
  11. 1.9 9 km SSE of Seldovia, Alaska
  12. 1.9 32 km SE of Port Graham, Alaska
  13. 1.9 53 km S of Port Graham, Alaska
  14. 1.6 Kenai Peninsula, Alaska
  15. 1.5 1 km N of Seldovia, 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 2018-07-13 — it released about 4,000 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.