Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near Middletown, CA
No earthquake was likely felt in Middletown in the 24 hours to 2:56 am PST (10:56 UTC). The last one was M 1.6, 9 km (6 mi) WNW, at 5:12 am PST on 10 November 2026, estimated intensity II (weak) in town. Every earthquake near Middletown
This page: a magnitude 1.8 earthquake was recorded 12 km (8 mi) southeast of Middletown, CA, at 5:39 pm PDT on 7 October 2023 (00:39 UTC), 6.3 km deep.
USGS: 12 km SE of Middletown, CA
32 km (20 mi) NE of Santa Rosa, CA · 101 km (63 mi) N of San Francisco, CA
- When
- 5:39 pm PDT on 7 October 2023 ()
- Where
- 12 km (8 mi) southeast of Middletown, CA · earthquakes near Middletown
- Magnitude
- M 1.8 (md)
- Depth
- 6.3 km below the surface
- Felt
- no reports yet
- Nearest
- Napa County, 25 km SE
- Nearest mapped fault
- Hunting Creek-Berryessa fault system, 8 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 1126 days ago
Earthquake alerts for Middletown, 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 13 km (8 mi) from the epicentre. In Middletown, 12 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: Angwin, Calistoga, Hidden Valley Lake, Deer Park, Saint Helena, Cobb.
How big was it?
This earthquake released about 17 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 5.8 870,000× the energy of this one
- Magna, Utah 2020 M 5.7 620,000× the energy of this one
- Around the size people start to feel M 3.0 55× the energy of this one
- This earthquake M 1.8 about 17 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 5.0 on 2016-12-14 — about 57,000 times the energy of this one.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 5.3 3 km E of Bloomfield, California · 49 km SSW of this epicentre
- 5.3 Northern California · 50 km SW 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 38.6867, -122.4987. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Napa County, CA | 25 km (16 mi) | SE | earthquakes near Napa County |
| Sonoma County, CA | 41 km (26 mi) | WSW | earthquakes near Sonoma County |
| Lake County, CA | 51 km (32 mi) | NNW | earthquakes near Lake County |
| Yolo County, CA | 52 km (32 mi) | E | earthquakes near Yolo County |
| Colusa County, CA | 59 km (37 mi) | NNE | earthquakes near Colusa County |
| Solano County, CA | 67 km (42 mi) | SE | earthquakes near Solano County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
59 earthquakes have been recorded within 50 km since this one.
- 1.6 9 km WNW of Cobb, CA
- 1.6 8 km NW of The Geysers, CA
- 2.0 3 km WNW of Anderson Springs, CA
- 1.7 10 km NW of The Geysers, CA
- 1.8 7 km NW of The Geysers, CA
- 2.4 7 km NW of The Geysers, CA
- 1.7 8 km NW of The Geysers, CA
- 1.8 6 km NW of The Geysers, CA
- 1.6 3 km NW of The Geysers, CA
- 1.8 9 km WNW of Cobb, CA
- 1.8 9 km NW of The Geysers, CA
- 1.9 12 km SE of Middletown, CA
- 1.6 6 km NW of The Geysers, CA
- 1.5 12 km SE of Middletown, CA
- 1.9 2 km NE of The Geysers, 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.