Earthquake · reviewed by a seismologist
M 4.0mb
89 km SSW of False Pass, Alaska
- When
- Magnitude
- M 4.0 (mb)
- Depth
- 38 km below the surface
- Felt
- no reports yet
- Measured shaking
- intensity I (ShakeMap)
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 943 days ago
This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.
How big was it?
This earthquake released about 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 11,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 500× the energy of this one
- Magna, Utah 2020 M 5.7 350× the energy of this one
- This earthquake M 4.0 about 15 tons of TNT
- Around the size people start to feel M 3.0 this one released 32× 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 54.0747, -163.7246. Map © OpenStreetMap contributors.
Aftershocks so far
56 earthquakes have been recorded within 50 km since this one.
- 2.5 94 km S of False Pass, Alaska
- 3.1 90 km S of False Pass, Alaska
- 2.9 106 km S of False Pass, Alaska
- 2.7 87 km S of False Pass, Alaska
- 2.2 108 km S of False Pass, Alaska
- 3.3 116 km SSW of False Pass, Alaska
- 2.1 113 km S of False Pass, Alaska
- 2.1 95 km S of False Pass, Alaska
- 2.1 110 km S of False Pass, Alaska
- 2.1 107 km S of False Pass, Alaska
- 2.2 76 km SSW of False Pass, Alaska
- 2.3 64 km SSW of False Pass, Alaska
- 2.1 40 km S of False Pass, Alaska
- 2.1 68 km S of False Pass, Alaska
- 2.8 105 km ESE of Akutan, 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 5.1 on 2021-01-11 — it released about 45 times the energy of this one.
From the QuakeIndex catalogue, built from the USGS FDSN event service.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.