QuakeIndex

Earthquake · reviewed by a seismologist

M 4.5mb

146 km SSE of Adak, Alaska

Yes. A magnitude 4.5 earthquake was recorded 146 km SSE of Adak, Alaska at 06:51 UTC on 2020-05-15, 21 km deep.

· 21 km deep · released about 85 tons 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 4.5 (mb)
Depth
21 km below the surface
Felt
no reports yet
Nearest mapped fault
Alaska-Aleutian subduction zone, 12 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 2295 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 138 km (86 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 85 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 2,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 89× the energy of this one
  3. Magna, Utah 2020 M 5.7 63× the energy of this one
  4. This earthquake M 4.5 about 85 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 180× 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 since 2016 was M 5.0 on 2016-06-29 — about 5.6 times the energy of this one.

Before 2016, the USGS record lists 9 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.0 101 km S of Adak, Alaska · 50 km NW of this epicentre
  2. 6.3 159 km SSE of Adak, Alaska · 17 km ESE of this epicentre
  3. 5.5 187 km SSE of Adak, Alaska · 47 km SSW of this epicentre
  4. 5.3 185 km S of Adak, Alaska · 48 km SSW of this epicentre
  5. 5.1 166 km SE of Adak, Alaska · 48 km E 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 50.6415, -175.8798. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 2.1 154 km S of Adak, Alaska
  2. 2.1 126 km SSE of Adak, Alaska
  3. 3.2 98 km SSE of Adak, Alaska
  4. 1.6 147 km SSE of Adak, Alaska
  5. 1.6 158 km SSE of Adak, Alaska
  6. 1.9 157 km S of Adak, Alaska
  7. 2.1 153 km SSE of Adak, Alaska
  8. 3.0 187 km SSE of Adak, Alaska
  9. 1.8 Andreanof Islands, Aleutian Islands, Alaska
  10. 2.5 163 km SSE of Adak, Alaska
  11. 2.3 161 km SSE of Adak, Alaska
  12. 2.6 170 km SSE of Adak, Alaska
  13. 2.1 167 km S of Adak, Alaska
  14. 2.1 164 km S of Adak, Alaska
  15. 2.8 172 km S 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.