QuakeIndex

Earthquake · reviewed by a seismologist

M 6.1mww

230 km WSW of Adak, Alaska

Yes. A magnitude 6.1 earthquake was recorded 230 km WSW of Adak, Alaska at 12:38 UTC on 2021-01-03, 21 km deep. 3 people have reported feeling it to USGS.

· 21 km deep · released about 21 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 6.1 (mww)
Depth
21 km below the surface
Felt
3 reports · strongest reported intensity III
Measured shaking
intensity VI (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 327 days ago

This was a strong earthquake. Damage is likely near the epicentre and it is felt over a wide area.

At this magnitude and depth, people at rest would likely notice it out to about 366 km (227 mi) from the epicentre. Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

How big was it?

This earthquake released about 21 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 7.1 would have released about 32 times as much.

  1. Ridgecrest, California 2019 M 7.1 32× the energy of this one
  2. Loma Prieta, California 1989 M 6.9 16× the energy of this one
  3. Northridge, California 1994 M 6.7 7.9× the energy of this one
  4. This earthquake M 6.1 about 21 kilotons of TNT
  5. Mineral, Virginia 2011 M 5.8 this one released 2.8× more
  6. Magna, Utah 2020 M 5.7 this one released 4× 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.

For this area

Tied for the largest within 50 km (31 mi) since 2016, with M 6.1 on 2020-01-26.

Before 2016, the USGS record lists 145 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 238 km WSW of Adak, Alaska · 10 km SSW of this epicentre
  2. 7.2 207 km WSW of Adak, Alaska · 25 km NE of this epicentre
  3. 6.9 203 km WSW of Adak, Alaska · 28 km ENE of this epicentre
  4. 6.9 231 km WSW of Adak, Alaska · 9 km NNW of this epicentre
  5. 6.8 235 km WSW of Adak, Alaska · 9 km NW of this epicentre

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 51.2199, -179.7930. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.9 220 km WSW of Adak, Alaska
  2. 1.8 237 km WSW of Adak, Alaska
  3. 1.7 216 km WSW of Adak, Alaska
  4. 2.0 198 km WSW of Adak, Alaska
  5. 2.0 237 km WSW of Adak, Alaska
  6. 1.6 253 km WSW of Adak, Alaska
  7. 1.7 222 km WSW of Adak, Alaska
  8. 3.2 250 km WSW of Adak, Alaska
  9. 1.9 241 km WSW of Adak, Alaska
  10. 1.6 194 km WSW of Adak, Alaska
  11. 1.9 230 km WSW of Adak, Alaska
  12. 2.9 247 km WSW of Adak, Alaska
  13. 3.4 202 km WSW of Adak, Alaska
  14. 2.0 192 km WSW of Adak, Alaska
  15. 2.3 224 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.

On USGS

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