QuakeIndex

Earthquake · reviewed by a seismologist

M 5.7mww

239 km WSW of Adak, Alaska

· 20 km deep · released about 5.4 kilotons 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 5.7 (mww)
Depth
20 km below the surface
Felt
1 report · 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.
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 280 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 5.4 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.7 would have released about 32 times as much.

  1. Loma Prieta, California 1989 M 6.9 63× the energy of this one
  2. Northridge, California 1994 M 6.7 32× the energy of this one
  3. Mineral, Virginia 2011 M 5.8 1.4× the energy of this one
  4. This earthquake M 5.7 about 5.4 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 11,000× 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 51.1069, -179.8500. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 1.9 215 km WSW of Adak, Alaska
  2. 2.0 233 km WSW of Adak, Alaska
  3. 2.8 239 km WSW of Adak, Alaska
  4. 2.9 241 km WSW of Adak, Alaska
  5. 3.4 221 km WSW of Adak, Alaska
  6. 2.2 240 km WSW of Adak, Alaska
  7. 1.7 195 km WSW of Adak, Alaska
  8. 2.8 227 km WSW of Adak, Alaska
  9. 1.6 219 km WSW of Adak, Alaska
  10. 3.0 239 km WSW of Adak, Alaska
  11. 3.9 261 km WSW of Adak, Alaska
  12. 2.3 245 km WSW of Adak, Alaska
  13. 2.5 211 km WSW of Adak, Alaska
  14. 3.3 242 km WSW of Adak, Alaska
  15. 2.6 220 km WSW of Adak, 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 6.1 on 2020-01-26 — it released about 4 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.