Earthquake · reviewed by a seismologist
M 3.9mw
3km N of San Lorenzo, CA
- When
- Magnitude
- M 3.9 (mw)
- Depth
- 9.2 km below the surface
- Felt
- 12071 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- Tsunami
- USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
- Nearest
- Alameda County, 20 km ESE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 552 days ago
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 12071 people have reported feeling it to USGS.
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.
- Northridge, California 1994 M 6.7 16,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 710× the energy of this one
- Magna, Utah 2020 M 5.7 500× the energy of this one
- This earthquake M 3.9 about 11 tons of TNT
- 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 37.7062, -122.1223. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction | |
|---|---|---|---|
| Alameda County, CA | 20 km (12 mi) | WNW of here | earthquakes near Alameda County |
| Contra Costa County, CA | 28 km (17 mi) | SSW of here | earthquakes near Contra Costa County |
| San Mateo County, CA | 39 km (24 mi) | NE of here | earthquakes near San Mateo County |
| Solano County, CA | 64 km (40 mi) | SSW of here | earthquakes near Solano County |
| Santa Clara County, CA | 66 km (41 mi) | NW of here | earthquakes near Santa Clara County |
| Marin County, CA | 67 km (42 mi) | SE of here | earthquakes near Marin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
52 earthquakes have been recorded within 50 km since this one.
- 3.1 6km WNW of Dublin, CA
- 1.5 5km E of Vallejo, CA
- 2.3 8km ESE of Fremont, CA
- 2.9 10km NE of Milpitas, CA
- 2.2 5km E of Vallejo, CA
- 1.8 1km NW of Diablo, CA
- 1.7 3km ESE of Pacheco, CA
- 1.7 6km WNW of Dublin, CA
- 1.6 5km E of Vallejo, CA
- 1.9 10km NE of Milpitas, CA
- 1.7 5km NW of Dublin, CA
- 2.6 6km S of Livermore, CA
- 2.4 11km NE of Milpitas, CA
- 1.8 5km ENE of Vallejo, CA
- 1.7 8km SSW of Livermore, 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 2019-10-15 — it released about 6.9 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.