QuakeIndex

Earthquake · reviewed by a seismologist

M 4.0mwr

262 km WNW of Port McNeill, Canada

· 10 km deep · released about 15 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 4.0 (mwr)
Depth
10 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1731 days ago

A magnitude 4.0 earthquake was recorded 262 km WNW of Port McNeill, Canada at 17:24 UTC on 2021-10-28. 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.

  1. Northridge, California 1994 M 6.7 11,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
  3. Magna, Utah 2020 M 5.7 350× the energy of this one
  4. This earthquake M 4.0 about 15 tons of TNT
  5. 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.

For this area

The largest earthquake within 50 km in our catalogue was M 6.2 on 2019-07-04 — about 2,000 times the energy of this one.

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 51.2110, -130.6933. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 3.9 247 km WNW of Port McNeill, Canada
  2. 4.1 264 km WNW of Port McNeill, Canada
  3. 4.2 286 km WNW of Port McNeill, Canada
  4. 4.2 268 km WNW of Port McNeill, Canada
  5. 4.7 279 km WNW of Port McNeill, Canada
  6. 4.0 270 km WNW of Port McNeill, Canada
  7. 6.5 271 km WNW of Port McNeill, Canada
  8. 4.4 230 km W of Port McNeill, Canada
  9. 4.3 234 km W of Port McNeill, Canada

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.