Earthquake · reviewed by a seismologist
M 3.9mw
31 km NNW of Covelo, CA
- When
- Magnitude
- M 3.9 (mw)
- Depth
- 8.3 km below the surface
- Felt
- 8 reports · strongest reported intensity IV
- Measured shaking
- intensity III (ShakeMap)
- USGS impact alert
- green
- Nearest
- Mendocino County, 66 km S
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 32 days ago
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 8 people have reported feeling it to USGS.
How big was it?
This earthquake released about 10 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.
- Northridge, California 1994 M 6.7 17,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 760× the energy of this one
- Magna, Utah 2020 M 5.7 540× the energy of this one
- This earthquake M 3.9 about 10 tons of TNT
- Around the size people start to feel M 3.0 this one released 21× 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 40.0245, -123.4460. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction | |
|---|---|---|---|
| Mendocino County, CA | 66 km (41 mi) | N of here | earthquakes near Mendocino County |
| Trinity County, CA | 75 km (46 mi) | SSW of here | earthquakes near Trinity County |
| Humboldt County, CA | 86 km (53 mi) | SSE of here | earthquakes near Humboldt County |
| Glenn County, CA | 101 km (63 mi) | WNW of here | earthquakes near Glenn County |
| Tehama County, CA | 104 km (65 mi) | W of here | earthquakes near Tehama County |
| Lake County, CA | 118 km (74 mi) | NNW of here | earthquakes near Lake County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
23 earthquakes have been recorded within 50 km since this one.
- 2.2 32 km NE of Redway, CA
- 1.7 16 km NNW of Redway, CA
- 1.4 13 km SSE of Redway, CA
- 1.8 3 km SE of Redway, CA
- 1.7 29 km N of Redway, CA
- 1.6 4 km ESE of Redway, CA
- 1.6 2 km ENE of Redway, CA
- 1.8 1 km N of Redway, CA
- 1.8 7 km E of Covelo, CA
- 1.7 29 km WSW of Hayfork, CA
- 1.9 10 km ENE of Rockport, CA
- 1.7 10 km ENE of Rockport, CA
- 2.7 32 km NNW of Covelo, CA
- 1.9 8 km N of Covelo, CA
- 2.6 32 km NW of Covelo, 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 4.5 on 2016-08-28 — it released about 8.2 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.