quarry blast · reviewed by a seismologist
M 1.6md
Earthquake near Napa, CA
No earthquake was likely felt in Napa in the 24 hours to 10:25 pm PST (06:25 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
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.6 quarry blast was recorded 5 km (3 mi) southeast of Napa, CA, at 11:25 am PDT on 18 September 2024 (18:25 UTC), less than 1 km deep.
USGS: 5 km SSE of Napa, CA
6 km (4 mi) SE of Napa, CA · 56 km (35 mi) NNE of San Francisco, CA
- When
- 11:25 am PDT on 18 September 2024 ()
- Where
- 5 km (3 mi) southeast of Napa, CA · earthquakes near Napa
- Magnitude
- M 1.6 (md)
- Depth
- -0.2 km below the surface
- Felt
- no reports yet
- Nearest
- Solano County, 27 km E
- Nearest mapped fault
- West Napa fault, 6 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 784 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 11 km (7 mi) from the epicentre. In Napa, 5 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 5 km, intensity II. Estimated for each town centre; each link is that town's own record.
USGS catalogues this as quarry blast, not an earthquake.
How big was it?
This earthquake released about 7.6 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 2,000,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,400,000× the energy of this one
- Around the size people start to feel M 3.0 130× the energy of this one
- This earthquake M 1.6 about 7.6 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 19,000 times the energy of this one.
Before 2016, the USGS record lists 3 earthquakes of M5 or more within 50 km:
- 6.0 The 2014 South Napa, California Earthquake · 8 km SW of this epicentre
- 5.4 South of Elmira, California · 30 km E of this epicentre
- 5.3 3 km E of Bloomfield, California · 49 km W 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 38.2642, -122.2460. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Solano County, CA | 27 km (17 mi) | E | earthquakes near Solano County |
| Napa County, CA | 28 km (17 mi) | NNW | earthquakes near Napa County |
| Contra Costa County, CA | 46 km (29 mi) | SE | earthquakes near Contra Costa County |
| Marin County, CA | 50 km (31 mi) | WSW | earthquakes near Marin County |
| Yolo County, CA | 55 km (34 mi) | NNE | earthquakes near Yolo 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
46 earthquakes have been recorded within 50 km since this one.
- 1.8 5 km SW of Clayton, CA
- 1.9 5 km SW of Clayton, CA
- 1.8 11 km E of Yountville, CA
- 2.6 3 km ENE of Saint Helena, CA
- 2.4 4 km ENE of Saint Helena, CA
- 1.6 3 km of Saint Helena, CA
- 1.7 1 km of Pleasant Hill, CA
- 1.8 3 km SSW of American Canyon, CA
- 1.8 9 km W of Rio Vista, CA
- 2.2 6 km E of Vallejo, CA
- 1.7 7 km NNE of Bay Point, CA
- 1.6 8 km S of Calistoga, CA
- 1.9 1 km SW of Pacheco, CA
- 1.6 5 km E of Green Valley, CA
- 1.5 6 km ESE of Santa Rosa, 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.