QuakeIndex

Earthquake · reviewed by a seismologist

M 5.7mww

204 km WNW of Adak, Alaska

Yes. A magnitude 5.7 earthquake was recorded 204 km WNW of Adak, Alaska at 11:04 UTC on 2018-02-08, 211 km deep. 2 people have reported feeling it to USGS.

· 211 km deep · released about 5.4 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 5.7 (mww)
Depth
211 km below the surface
Felt
2 reports · strongest reported intensity IV
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 1191 days ago

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 203 km (126 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 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.

For this area

The largest earthquake within 50 km (31 mi) since our catalogue begins in 2016. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

  1. 6.4 170 km WNW of Adak, Alaska · 34 km ESE of this epicentre
  2. 5.4 174 km WNW of Adak, Alaska · 35 km E of this epicentre
  3. 5.1 193 km WNW of Adak, Alaska · 11 km SE of this epicentre
  4. 5.0 224 km WNW of Adak, Alaska · 38 km SW 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 52.5917, -179.3839. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.7 175 km WNW of Adak, Alaska
  2. 2.0 187 km WNW of Adak, Alaska
  3. 3.1 170 km WNW of Adak, Alaska
  4. 2.5 172 km WNW of Adak, Alaska
  5. 2.4 197 km WNW of Adak, Alaska
  6. 4.0 169 km WNW of Adak, Alaska
  7. 3.7 184 km WNW of Adak, Alaska
  8. 3.2 204 km W of Adak, Alaska
  9. 4.6 173 km WNW of Adak, Alaska
  10. 3.9 179 km WNW of Adak, Alaska
  11. 3.2 220 km W of Adak, Alaska
  12. 3.9 185 km WNW of Adak, Alaska
  13. 2.5 200 km W of Adak, Alaska
  14. 4.6 Andreanof Islands, Aleutian Islands, Alaska
  15. 2.8 193 km W 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.