QuakeIndex

Earthquake · reviewed by a seismologist

M 3.9mb

off the coast of Washington

· 12 km deep · released about 11 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 3.9 (mb)
Depth
12 km below the surface
Felt
no reports yet
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1301 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 16,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
  3. Magna, Utah 2020 M 5.7 500× the energy of this one
  4. This earthquake M 3.9 about 11 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 22× 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 47.8402, -128.9233. Map © OpenStreetMap contributors.

Aftershocks so far

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

  1. 4.0 278 km SW of Tofino, Canada
  2. 3.9 263 km SW of Tofino, Canada
  3. 3.9 254 km SW of Tofino, Canada
  4. 3.5 265 km SW of Tofino, Canada
  5. 3.4 288 km SW of Tofino, Canada
  6. 3.1 263 km SW of Tofino, Canada
  7. 3.2 241 km SW of Tofino, Canada
  8. 3.0 253 km WSW of Tofino, Canada
  9. 4.8 283 km SW of Tofino, Canada
  10. 3.1 291 km SW of Tofino, Canada
  11. 4.1 299 km SW of Tofino, Canada
  12. 4.9 259 km WSW of Tofino, Canada
  13. 3.3 269 km SW of Tofino, Canada
  14. 3.8 293 km SW of Tofino, Canada
  15. 4.1 246 km SW of Tofino, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.6 on 2020-10-05 — it released about 11 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.