QuakeIndex

Earthquake · reviewed by a seismologist

M 5.9ml

127 km SE of Chignik, Alaska

· 0.8 km deep · released about 11 kilotons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N
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 5.9 (ml)
Depth
0.8 km below the surface
Felt
14 reports · strongest reported intensity IV
Measured shaking
intensity III (ShakeMap)
USGS impact alert
green
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 279 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 14 people have reported feeling it to USGS.

How big was it?

This earthquake released about 11 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.9 would have released about 32 times as much.

  1. Ridgecrest, California 2019 M 7.1 63× the energy of this one
  2. Loma Prieta, California 1989 M 6.9 32× the energy of this one
  3. Northridge, California 1994 M 6.7 16× the energy of this one
  4. This earthquake M 5.9 about 11 kilotons of TNT
  5. Mineral, Virginia 2011 M 5.8 this one released 1.4× more
  6. Magna, Utah 2020 M 5.7 this one released 2× 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 55.3726, -157.2050. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.2 131 km SSE of Chignik, Alaska
  2. 3.6 139 km SE of Perryville, Alaska
  3. 2.7 155 km SE of Chignik, Alaska
  4. 3.0 125 km SE of Perryville, Alaska
  5. 2.9 145 km SE of Perryville, Alaska
  6. 3.4 166 km SE of Chignik, Alaska
  7. 2.5 95 km SE of Chignik, Alaska
  8. 3.3 148 km SE of Perryville, Alaska
  9. 3.2 135 km SE of Chignik, Alaska
  10. 3.0 162 km SE of Chignik, Alaska
  11. 3.2 166 km SSE of Chignik, Alaska
  12. 3.4 140 km SE of Perryville, Alaska
  13. 4.6 148 km SE of Chignik, Alaska
  14. 3.2 145 km SE of Perryville, Alaska
  15. 3.3 113 km SE of Chignik, 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 4.9 on 2017-02-27.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

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