Earthquake · reviewed by a seismologist
M 2.9ml
Earthquake near Rio Vista, CA
No earthquake was likely felt in Rio Vista in the 24 hours to 4:49 pm PST (00:49 UTC). The last one was M 3.1, 35 km (22 mi) SSW, at 12:25 am PDT on 12 September 2026, estimated intensity II (weak) in town; 257 felt reports to USGS. Every earthquake near Rio Vista
This page: a magnitude 2.9 earthquake was recorded 5 km (3 mi) southeast of Rio Vista, CA, at 7:42 am PDT on 23 October 2023 (14:42 UTC), less than 1 km deep. 108 people have reported feeling it to USGS.
USGS: 4 km SE of Rio Vista, CA
77 km (48 mi) ENE of San Francisco, CA · 21 km (13 mi) NE of Antioch, CA
- When
- 7:42 am PDT on 23 October 2023 ()
- Where
- 5 km (3 mi) southeast of Rio Vista, CA · earthquakes near Rio Vista
- Magnitude
- M 2.9 (ml)
- Depth
- 0.0 km below the surface
- Felt
- 108 reports · strongest reported intensity IV
- Nearest
- Solano County, 29 km WNW
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 462 days ago
Earthquake alerts for Rio Vista, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 31 km (19 mi) from the epicentre. In Rio Vista, 5 km away, the estimate is intensity III (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: Rio Vista 5 km, intensity III · Oakley 16 km, intensity III · Antioch 19 km, intensity II · Brentwood 22 km, intensity II · Pittsburg 23 km, intensity II · Discovery Bay 25 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 630 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 24,000× the energy of this one
- Magna, Utah 2020 M 5.7 17,000× the energy of this one
- Around the size people start to feel M 3.0 1.5× the energy of this one
- This earthquake M 2.9 about 630 lb of TNT
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.
For this area
The largest earthquake within 50 km since 2016 was M 4.5 on 2019-10-15 — about 230 times the energy of this one.
Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:
- 5.8 The 1980 Livermore, California Earthquake · 34 km SSW of this epicentre
- 5.4 South of Elmira, California · 28 km NW of this epicentre
- 5.4 9 km NE of Livermore, California · 43 km S of this epicentre
- 5.1 11 km E of Blackhawk, California · 37 km SSW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 38.1317, -121.6575. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Solano County, CA | 29 km (18 mi) | WNW | earthquakes near Solano County |
| Contra Costa County, CA | 35 km (22 mi) | SW | earthquakes near Contra Costa County |
| San Joaquin County, CA | 40 km (25 mi) | ESE | earthquakes near San Joaquin County |
| Sacramento County, CA | 45 km (28 mi) | NE | earthquakes near Sacramento County |
| Alameda County, CA | 58 km (36 mi) | SSW | earthquakes near Alameda County |
| Yolo County, CA | 65 km (40 mi) | NNW | earthquakes near Yolo County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
44 earthquakes have been recorded within 50 km since this one.
- 1.7 5 km E of Vallejo, CA
- 1.6 2 km N of Livermore, CA
- 1.6 6 km ENE of Vallejo, CA
- 1.8 10 km ENE of Blackhawk, CA
- 1.8 10 km SSW of Brentwood, CA
- 1.5 6 km E of Walnut Creek, CA
- 1.7 1 km W of Pacheco, CA
- 2.0 10 km ESE of Clayton, CA
- 1.9 11 km E of Blackhawk, CA
- 2.6 3 km SE of Pleasant Hill, CA
- 1.9 2 km NW of Alamo, CA
- 1.8 2 km SE of Pacheco, CA
- 1.5 5 km E of Vallejo, CA
- 2.3 4 km ENE of Walnut Creek, CA
- 1.6 1 km SSW of Alamo, 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.
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.