Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near Napa, CA
No earthquake was likely felt in Napa in the 24 hours to 12:50 am PST (08:50 UTC). The last one was M 2.4, 6 km (3 mi) SE, at 10:47 am PDT on 6 October 2026, estimated intensity III (weak) in town; 1 felt report to USGS. Every earthquake near Napa
This page: a magnitude 1.8 earthquake was recorded 10 km (6 mi) northeast of Napa, CA, at 7:03 am PDT on 11 August 2021 (14:03 UTC), 13 km deep.
USGS: 10km NE of Napa, CA
11 km (7 mi) ENE of Napa, CA · 66 km (41 mi) NNE of San Francisco, CA
- When
- 7:03 am PDT on 11 August 2021 ()
- Where
- 10 km (6 mi) northeast of Napa, CA · earthquakes near Napa
- Magnitude
- M 1.8 (md)
- Depth
- 13 km below the surface
- Felt
- no reports yet
- Nearest
- Napa County, 21 km NNW
- Nearest mapped fault
- Green Valley fault, under 1 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1911 days ago
Earthquake alerts for Napa, 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 minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 1 km (1 mi) from the epicentre. In Napa, 10 km away, the estimate is intensity II (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.
Earthquakes near other towns within 30 km: Green Valley, Yountville, Fairfield, Vacaville, Suisun, American Canyon.
How big was it?
This earthquake released about 13 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 840,000× the energy of this one
- Around the size people start to feel M 3.0 75× the energy of this one
- This earthquake M 1.8 about 13 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 12,000 times the energy of this one.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 6.0 The 2014 South Napa, California Earthquake · 18 km SSW of this epicentre
- 5.4 South of Elmira, California · 27 km ESE 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 38.3502, -122.1980. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Napa County, CA | 21 km (13 mi) | NNW | earthquakes near Napa County |
| Solano County, CA | 24 km (15 mi) | ESE | earthquakes near Solano County |
| Yolo County, CA | 45 km (28 mi) | NE | earthquakes near Yolo County |
| Contra Costa County, CA | 53 km (33 mi) | SSE | earthquakes near Contra Costa County |
| Marin County, CA | 58 km (36 mi) | SW | earthquakes near Marin County |
| Sonoma County, CA | 66 km (41 mi) | WNW | earthquakes near Sonoma County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
36 earthquakes have been recorded within 50 km since this one.
- 2.0 4km ENE of El Sobrante, CA
- 2.8 4km ENE of El Sobrante, CA
- 2.1 4km ENE of El Sobrante, CA
- 1.8 15km ESE of Hidden Valley Lake, CA
- 1.6 6km E of Vallejo, CA
- 2.0 10km NNE of Angwin, CA
- 2.1 3km WNW of Crockett, CA
- 2.1 6km SSW of Yountville, CA
- 1.9 5km SW of Pacheco, CA
- 1.8 2km SE of Pacheco, CA
- 1.5 9km NE of Santa Rosa, CA
- 1.6 11km NE of Napa, CA
- 3.2 3km ESE of Santa Rosa, CA
- 1.7 6km SW of Calistoga, CA
- 2.7 1km SSE of Vallejo, 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.