Earthquake · reviewed by a seismologist
M 4.0mw
11km WSW of Petrolia, CA
- When
- Magnitude
- M 4.0 (mw)
- Depth
- 32 km below the surface
- Felt
- 8 reports · strongest reported intensity III
- Measured shaking
- intensity III (ShakeMap)
- USGS impact alert
- green
- Nearest
- Humboldt County, 62 km NE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1786 days ago
This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 8 people have reported feeling it to USGS.
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.
- Northridge, California 1994 M 6.7 11,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 500× the energy of this one
- Magna, Utah 2020 M 5.7 350× the energy of this one
- This earthquake M 4.0 about 15 tons of TNT
- 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.
Where
Epicentre 40.2815, -124.4008. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction | |
|---|---|---|---|
| Humboldt County, CA | 62 km (39 mi) | SW of here | earthquakes near Humboldt County |
| Trinity County, CA | 116 km (72 mi) | WSW of here | earthquakes near Trinity County |
| Mendocino County, CA | 125 km (78 mi) | NW of here | earthquakes near Mendocino County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
53 earthquakes have been recorded within 50 km since this one.
- 2.9 6km NNE of Petrolia, CA
- 2.8 6km NNE of Petrolia, CA
- 1.8 6km NNE of Petrolia, CA
- 2.4 8km SSE of Petrolia, CA
- 2.4 5km NNW of Petrolia, CA
- 1.7 5km NNE of Petrolia, CA
- 2.5 3km N of Petrolia, CA
- 3.0 6km NNE of Petrolia, CA
- 2.5 6km N of Petrolia, CA
- 2.6 6km NNE of Petrolia, CA
- 2.3 4km NNE of Petrolia, CA
- 4.4 5km NNE of Petrolia, CA
- 2.5 19km W of Petrolia, CA
- 2.4 26km WNW of Petrolia, CA
- 2.9 23km W of Petrolia, CA
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 5.6 on 2019-06-23 — it released about 230 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.