115km W of Petrolia, CA

2023-07-03 17:56 UTC · 26 km deep · released about 16 tons of TNT

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: 2023-07-03 17:56 UTC
Magnitude: M 4.0 (mw)
Depth: 26 km below the surface
Felt: 7 reports · strongest reported intensity IV
Measured shaking: intensity II (ShakeMap)
USGS impact alert: green
Status: Reviewed by a seismologist

USGS · last changed by USGS 877 days ago · we first saw it 877 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 7 people have reported feeling it to USGS.

How big was it?

This earthquake released about 16 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 10,000× the energy of this one
Mineral, Virginia 2011 M 5.8 470× the energy of this one
Magna, Utah 2020 M 5.7 330× the energy of this one
This earthquake M 4.0 about 16 tons of TNT
Around the size people start to feel M 3.0 this one released 34× 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

Map loads when it scrolls into view

Epicentre 40.4000, -125.6437. Map © OpenStreetMap contributors.

Aftershocks so far

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

3.7 108 km WNW of Petrolia, CA 12:17 UTC
2.6 75 km WNW of Petrolia, CA 06:22 UTC
2.8 87 km WNW of Petrolia, CA 07:27 UTC
2.4 84 km WNW of Petrolia, CA 19:16 UTC
2.3 160 km W of Ferndale, California 21:47 UTC
2.6 94 km WNW of Petrolia, CA 00:25 UTC
2.6 155 km W of Ferndale, California 19:21 UTC
2.7 76 km W of Petrolia, CA 04:41 UTC
2.6 117 km WNW of Petrolia, CA 15:07 UTC
2.8 91 km WNW of Petrolia, CA 09:37 UTC
2.7 81 km WNW of Petrolia, CA 13:52 UTC
2.6 150 km W of Ferndale, California 03:49 UTC
2.4 81 km WNW of Ferndale, CA 12:59 UTC
2.7 138 km WNW of Petrolia, CA 08:38 UTC
2.8 96 km WNW of Petrolia, CA 00:03 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:24 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 6.6 on 2016-12-08 — it released about 7,400 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.