Earthquake · reviewed by a seismologist
M 3.9mw
5 km SE of San Ramon, CA
- When
- Magnitude
- M 3.9 (mw)
- Depth
- 10 km below the surface
- Felt
- 2028 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- USGS impact alert
- green
- Nearest
- Alameda County, 11 km SSE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 192 days ago
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 2028 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 37.7472, -121.9455. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction | |
|---|---|---|---|
| Alameda County, CA | 11 km (7 mi) | NNW of here | earthquakes near Alameda County |
| Contra Costa County, CA | 19 km (12 mi) | S of here | earthquakes near Contra Costa County |
| San Mateo County, CA | 53 km (33 mi) | NE of here | earthquakes near San Mateo County |
| Solano County, CA | 58 km (36 mi) | S of here | earthquakes near Solano County |
| Santa Clara County, CA | 63 km (39 mi) | NNW of here | earthquakes near Santa Clara County |
| San Joaquin County, CA | 63 km (39 mi) | WSW of here | earthquakes near San Joaquin County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 2.3 3 km ESE of San Ramon, CA
- 2.0 3 km ESE of San Ramon, CA
- 1.7 3 km ESE of San Ramon, CA
- 2.7 4 km ESE of San Ramon, CA
- 3.0 3 km ESE of San Ramon, CA
- 1.8 5 km ESE of San Ramon, CA
- 1.9 5 km ESE of San Ramon, CA
- 1.6 4 km ESE of San Ramon, CA
- 2.6 4 km ESE of San Ramon, CA
- 2.8 4 km ESE of San Ramon, CA
- 2.9 4 km ESE of San Ramon, CA
- 1.8 4 km ESE of San Ramon, CA
- 1.7 7 km ENE of Vallejo, CA
- 1.7 9 km E of Alum Rock, CA
- 1.5 4 km ESE of San Ramon, 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.