QuakeIndex

Earthquake · reviewed by a seismologist

M 5.5mww

229 km W of Port McNeill, Canada

· 10 km deep · released about 2.7 kilotons 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 5.5 (mww)
Depth
10 km below the surface
Felt
10 reports · strongest reported intensity III
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 1038 days ago

A magnitude 5.5 earthquake was recorded 229 km W of Port McNeill, Canada at 11:28 UTC on 2023-09-17. 10 people have reported feeling it to USGS. This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

How big was it?

This earthquake released about 2.7 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 63× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2.8× the energy of this one
  3. Magna, Utah 2020 M 5.7 2× the energy of this one
  4. This earthquake M 5.5 about 2.7 kilotons of TNT
  5. Around the size people start to feel M 3.0 this one released 5,600× 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 6.3 on 2019-12-25 — about 16 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 50.8131, -130.3127. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.0 207 km W of Port McNeill, Canada
  2. 4.2 212 km W of Port McNeill, Canada
  3. 5.2 210 km W of Port McNeill, Canada
  4. 4.6 211 km W of Port McNeill, Canada
  5. 5.0 224 km W of Port McNeill, Canada
  6. 4.4 192 km W of Port McNeill, Canada
  7. 4.2 207 km W of Port McNeill, Canada
  8. 4.3 211 km W of Port McNeill, Canada
  9. 4.5 219 km W of Port McNeill, Canada
  10. 4.8 201 km W of Port McNeill, Canada
  11. 4.3 224 km W of Port McNeill, Canada
  12. 4.4 230 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.