Earthquake · reviewed by a seismologist
M 3.1ml
Earthquake near Santa Rosa, CA
No earthquake was likely felt in Santa Rosa in the 24 hours to 1:28 pm PST (21:28 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 3.1 earthquake was recorded 33 km (20 mi) north of Santa Rosa, CA, at 11:38 pm PST on 9 December 2018 (07:38 UTC), 1.5 km deep. 9 people have reported feeling it to USGS.
USGS: 5km SSW of Anderson Springs, CA
32 km (20 mi) N of Santa Rosa, CA · 110 km (68 mi) NNW of San Francisco, CA
- When
- 11:38 pm PST on 9 December 2018 ()
- Where
- 33 km (20 mi) north of Santa Rosa, CA · earthquakes near Santa Rosa
- Magnitude
- M 3.1 (ml)
- Depth
- 1.5 km below the surface
- Felt
- 9 reports · strongest reported intensity III
- Nearest
- Sonoma County, 29 km SW
- Nearest mapped fault
- Maacama fault, 9 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 2826 days ago
Earthquake alerts for Santa Rosa, CA
Get a notification in this browser when USGS records an earthquake near Santa Rosa, CA. No account or email needed.
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 41 km (25 mi) from the epicentre. In Santa Rosa, 33 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 10 km, intensity III · Healdsburg 19 km, intensity III · Calistoga 21 km, intensity II · Windsor 22 km, intensity II · Clearlake 26 km, intensity II · Cloverdale 27 km, intensity II · Angwin 30 km, intensity II · Santa Rosa 33 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.
- Northridge, California 1994 M 6.7 260,000× the energy of this one
- Mineral, Virginia 2011 M 5.8 12,000× the energy of this one
- Magna, Utah 2020 M 5.7 8,200× the energy of this one
- This earthquake M 3.1 about 1,300 lb of TNT
- Around the size people start to feel M 3.0 this one released 1.4× 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 760 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 · 47 km S of this epicentre
- 5.3 Northern California · 47 km S 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 38.7357, -122.7235. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Sonoma County, CA | 29 km (18 mi) | SW | earthquakes near Sonoma County |
| Lake County, CA | 41 km (26 mi) | N | earthquakes near Lake County |
| Napa County, CA | 43 km (27 mi) | SE | earthquakes near Napa County |
| Colusa County, CA | 65 km (40 mi) | NE | earthquakes near Colusa County |
| Yolo County, CA | 71 km (44 mi) | E | earthquakes near Yolo County |
| Marin County, CA | 76 km (47 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.
- 2.1 7km WNW of The Geysers, CA
- 1.7 1km NNW of The Geysers, CA
- 1.6 3km NW of The Geysers, CA
- 1.7 0km NNE of The Geysers, CA
- 1.5 7km WNW of The Geysers, CA
- 1.8 4km E of Penngrove, CA
- 1.6 6km WNW of The Geysers, CA
- 1.8 15km ESE of Angwin, CA
- 1.6 7km NW of The Geysers, CA
- 1.9 9km SW of Kelseyville, CA
- 1.8 6km WNW of Cobb, CA
- 1.5 9km NW of The Geysers, CA
- 2.2 6km NW of The Geysers, CA
- 1.9 4km WNW of The Geysers, CA
- 2.1 1km N 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.