QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5ml

161 km WSW of Adak, Alaska

Yes. A magnitude 1.5 earthquake was recorded 161 km WSW of Adak, Alaska at 05:25 UTC on 2019-07-23, 12 km deep.

· 12 km deep · released about 5.4 lb 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 1.5 (ml)
Depth
12 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2645 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
  3. Around the size people start to feel M 3.0 180× the energy of this one
  4. This earthquake M 1.5 about 5.4 lb of TNT

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 since 2016 was M 6.2 on 2017-05-08 — about 11,000,000 times the energy of this one.

Before 2016, the USGS record lists 201 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.2 162 km WSW of Adak, Alaska · 15 km S of this epicentre
  2. 7.2 207 km WSW of Adak, Alaska · 47 km WSW of this epicentre
  3. 7.0 148 km WSW of Adak, Alaska · 32 km SE of this epicentre
  4. 6.9 203 km WSW of Adak, Alaska · 44 km WSW of this epicentre
  5. 6.9 151 km WSW of Adak, Alaska · 26 km SE 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 51.5523, -178.9074. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.7 153 km WSW of Adak, Alaska
  2. 1.6 Andreanof Islands, Aleutian Islands, Alaska
  3. 1.5 125 km WSW of Adak, Alaska
  4. 1.5 126 km W of Adak, Alaska
  5. 1.7 128 km W of Adak, Alaska
  6. 1.7 143 km WSW of Adak, Alaska
  7. 2.2 142 km WSW of Adak, Alaska
  8. 1.8 185 km WSW of Adak, Alaska
  9. 2.1 169 km WSW of Adak, Alaska
  10. 2.0 165 km W of Adak, Alaska
  11. 2.0 191 km WSW of Adak, Alaska
  12. 3.1 178 km WSW of Adak, Alaska
  13. 4.0 192 km WSW of Adak, Alaska
  14. 2.4 177 km WSW of Adak, Alaska
  15. 4.4 Andreanof Islands, Aleutian Islands, 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.