Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Napa, CA
No earthquake was likely felt in Napa in the 24 hours to 11:06 pm PST (07:06 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 1.6 earthquake was recorded 8 km (5 mi) southwest of Napa, CA, at 11:54 pm PDT on 15 August 2023 (06:54 UTC), 7.0 km deep. 1 person has reported feeling it to USGS.
USGS: 8 km SW of Napa, CA
7 km (4 mi) SSW of Napa, CA · 52 km (32 mi) N of San Francisco, CA
- When
- 11:54 pm PDT on 15 August 2023 ()
- Where
- 8 km (5 mi) southwest of Napa, CA · earthquakes near Napa
- Magnitude
- M 1.6 (md)
- Depth
- 7.0 km below the surface
- Felt
- 1 report · strongest reported intensity III
- Nearest
- Napa County, 30 km N
- Nearest mapped fault
- West Napa fault, 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 1183 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 8 km (5 mi) from the epicentre. In Napa, 8 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.
Likely felt in: Napa 8 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 6.6 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,300,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
- Around the size people start to feel M 3.0 140× the energy of this one
- This earthquake M 1.6 about 6.6 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 22,000 times the energy of this one.
Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:
- 6.0 The 2014 South Napa, California Earthquake · 4 km SE of this epicentre
- 5.4 South of Elmira, California · 39 km E of this epicentre
- 5.3 3 km E of Bloomfield, California · 42 km WNW of this epicentre
- 5.3 Northern California · 44 km WNW 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 38.2418, -122.3358. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Napa County, CA | 30 km (18 mi) | N | earthquakes near Napa County |
| Solano County, CA | 35 km (22 mi) | E | earthquakes near Solano County |
| Marin County, CA | 42 km (26 mi) | WSW | earthquakes near Marin County |
| Contra Costa County, CA | 49 km (31 mi) | SE | earthquakes near Contra Costa County |
| Sonoma County, CA | 60 km (37 mi) | WNW | earthquakes near Sonoma County |
| Yolo County, CA | 62 km (38 mi) | NE | earthquakes near Yolo County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
26 earthquakes have been recorded within 50 km since this one.
- 1.8 2 km ENE of Berkeley, CA
- 2.5 2 km ENE of Berkeley, CA
- 2.1 2 km E of Pacheco, CA
- 2.1 1 km E of Pinole, CA
- 1.6 6 km ESE of Santa Venetia, CA
- 2.0 1 km E of Pacheco, CA
- 1.8 1 km SSE of Pacheco, CA
- 2.0 2 km ENE of Berkeley, CA
- 1.8 3 km W of Orinda, CA
- 2.5 3 km NNW of Piedmont, CA
- 1.6 11 km ENE of Yountville, CA
- 1.8 6 km ESE of Santa Venetia, CA
- 1.5 6 km NNE of Orinda, CA
- 1.8 8 km SW of Calistoga, CA
- 1.8 11 km E of Yountville, 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.