Earthquake · reviewed by a seismologist
M 3.9mw
Earthquake near Santa Rosa, CA
No earthquake was likely felt in Santa Rosa in the 24 hours to 11:57 pm PST (07:57 UTC). The last one was M 1.9, 5 km (3 mi) NE, at 2:01 pm PDT on 23 October 2026, estimated intensity II (weak) in town. Every earthquake near Santa Rosa
This page: a magnitude 3.9 earthquake was recorded 44 km (27 mi) north of Santa Rosa, CA, at 2:30 pm PDT on 8 October 2023 (21:30 UTC), 1.8 km deep. 72 people have reported feeling it to USGS.
USGS: 7 km NW of The Geysers, CA
43 km (27 mi) NNW of Santa Rosa, CA · 121 km (75 mi) NNW of San Francisco, CA
- When
- 2:30 pm PDT on 8 October 2023 ()
- Where
- 44 km (27 mi) north of Santa Rosa, CA · earthquakes near Santa Rosa
- Magnitude
- M 3.9 (mw)
- Depth
- 1.8 km below the surface
- Felt
- 72 reports · strongest reported intensity IV
- Measured shaking
- intensity IV (ShakeMap)
- Nearest
- Lake County, 32 km N
- Nearest mapped fault
- Konocti Bay fault, 10 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 764 days ago
Earthquake alerts for Santa Rosa, 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 87 km (54 mi) from the epicentre. In Santa Rosa, 44 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: Cobb 7 km, intensity IV · Cloverdale 19 km, intensity III · Clearlake 21 km, intensity III · Healdsburg 25 km, intensity III · Lakeport 26 km, intensity III · Windsor 31 km, intensity III · Calistoga 34 km, intensity III · Upper Lake 39 km, intensity III. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 9.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 18,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 790× the energy of this one
- Magna, Utah 2020 M 5.7 560× the energy of this one
- This earthquake M 3.9 about 9.6 tons of TNT
- Around the size people start to feel M 3.0 this one released 20× more
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 51 times the energy of this one.
Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:
- 5.2 6 km ESE of Talmage, California · 41 km NW 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 38.8272, -122.8040. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Lake County, CA | 32 km (20 mi) | N | earthquakes near Lake County |
| Sonoma County, CA | 35 km (22 mi) | SSW | earthquakes near Sonoma County |
| Napa County, CA | 55 km (34 mi) | SE | earthquakes near Napa County |
| Colusa County, CA | 63 km (39 mi) | NE | earthquakes near Colusa County |
| Yolo County, CA | 80 km (50 mi) | ESE | earthquakes near Yolo County |
| Marin County, CA | 86 km (54 mi) | S | earthquakes near Marin 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.
- 2.0 7 km NW of The Geysers, CA
- 1.7 12 km SE of Middletown, CA
- 1.5 8 km NW of The Geysers, CA
- 1.7 1 km NNW of The Geysers, CA
- 1.6 4 km WNW of The Geysers, CA
- 1.8 8 km SE of Cloverdale, CA
- 1.5 2 km NE of The Geysers, CA
- 2.9 7 km WNW of The Geysers, CA
- 2.3 6 km W of Cobb, CA
- 2.3 8 km E of Lower Lake, CA
- 1.6 7 km NW of The Geysers, CA
- 1.9 10 km WNW of The Geysers, CA
- 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
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.