QuakeIndex

Earthquake · reviewed by a seismologist

M 4.7ml

110 km SSE of Port Graham, Alaska

· 46 km deep · released about 170 tons 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 4.7 (ml)
Depth
46 km below the surface
Felt
7 reports · strongest reported intensity III
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Tsunami
USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2108 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 7 people have reported feeling it to USGS.

How big was it?

This earthquake released about 170 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.7 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 1,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 45× the energy of this one
  3. Magna, Utah 2020 M 5.7 32× the energy of this one
  4. This earthquake M 4.7 about 170 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 350× 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 58.5157, -150.7842. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.9 91 km SSE of Halibut Cove, Alaska
  2. 2.4 99 km ENE of Ouzinkie, Alaska
  3. 1.8 82 km ENE of Ouzinkie, Alaska
  4. 1.7 82 km ENE of Ouzinkie, Alaska
  5. 2.2 101 km NE of Ouzinkie, Alaska
  6. 1.8 100 km ENE of Ouzinkie, Alaska
  7. 1.8 92 km ENE of Ouzinkie, Alaska
  8. 2.4 87 km ENE of Ouzinkie, Alaska
  9. 1.9 102 km ENE of Ouzinkie, Alaska
  10. 1.6 104 km ENE of Ouzinkie, Alaska
  11. 2.0 89 km ENE of Ouzinkie, Alaska
  12. 1.7 96 km SSE of Halibut Cove, Alaska
  13. 1.6 100 km ENE of Ouzinkie, Alaska
  14. 2.0 Gulf of Alaska
  15. 2.7 104 km ENE of Ouzinkie, 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 5.0 on 2019-06-07 — 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.