258 km W of Ferndale, California

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 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 350,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
4. This earthquake M 3.0 about 950 lb of TNT

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 40.6224, -127.3185. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.3 267 km W of Ferndale, California 15:10 UTC
2. 3.1 255 km W of Ferndale, California 17:57 UTC
3. 4.4 246 km W of Ferndale, California 02:57 UTC
4. 3.3 262 km W of Ferndale, California 00:53 UTC
5. 2.8 253 km W of Ferndale, California 18:12 UTC
6. 2.5 off the coast of Northern California 15:42 UTC
7. 2.9 off the coast of Northern California 20:32 UTC
8. 3.5 235 km W of Ferndale, California 09:03 UTC
9. 3.4 231 km W of Ferndale, California 20:26 UTC
10. 3.1 264 km W of Ferndale, California 21:25 UTC
11. 3.3 252 km WNW of Ferndale, California 20:57 UTC
12. 3.3 246 km W of Ferndale, California 08:22 UTC
13. 2.8 off the coast of Northern California 13:25 UTC
14. 2.9 272 km W of Ferndale, California 01:03 UTC
15. 2.9 254 km W of Ferndale, California 19:28 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 21:47 UTC. 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 5.7 on 2017-09-22 — it released about 11,000 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.