Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Santa Rosa, CA
No earthquake was likely felt in Santa Rosa in the 24 hours to 3:25 am PST (11:25 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 1.6 earthquake was recorded 26 km (16 mi) east of Santa Rosa, CA, at 5:35 pm PDT on 20 May 2021 (00:35 UTC), 10 km deep.
USGS: 6km SE of St. Helena, CA
77 km (48 mi) N of San Francisco, CA · 22 km (14 mi) NNW of Napa, CA
- When
- 5:35 pm PDT on 20 May 2021 ()
- Where
- 26 km (16 mi) east of Santa Rosa, CA · earthquakes near Santa Rosa
- Magnitude
- M 1.6 (md)
- Depth
- 10 km below the surface
- Felt
- no reports yet
- Nearest
- Napa County, 9 km ENE
- Nearest mapped fault
- West Napa fault, 2 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 1998 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 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 4 km (2 mi) from the epicentre. In Santa Rosa, 26 km away, the estimate is intensity I (not felt). 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: Saint Helena, Deer Park, Yountville, Angwin, Kenwood, Eldridge.
How big was it?
This earthquake released about 7.1 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 2,100,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,500,000× 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 7.1 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 4.2 on 2018-01-18 — about 9,100 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 · 30 km SSE of this epicentre
- 5.4 South of Elmira, California · 49 km ESE of this epicentre
- 5.3 3 km E of Bloomfield, California · 38 km WSW of this epicentre
- 5.3 Northern California · 39 km WSW 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 38.4700, -122.4222. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Napa County, CA | 9 km (6 mi) | ENE | earthquakes near Napa County |
| Sonoma County, CA | 44 km (28 mi) | W | earthquakes near Sonoma County |
| Solano County, CA | 48 km (30 mi) | ESE | earthquakes near Solano County |
| Yolo County, CA | 51 km (32 mi) | ENE | earthquakes near Yolo County |
| Marin County, CA | 54 km (34 mi) | SSW | earthquakes near Marin County |
| Contra Costa County, CA | 74 km (46 mi) | SE | earthquakes near Contra Costa County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
23 earthquakes have been recorded within 50 km since this one.
- 2.3 11km E of Hidden Valley Lake, CA
- 1.6 13km ESE of Angwin, CA
- 1.6 14km ESE of Angwin, CA
- 2.1 10km ESE of Angwin, CA
- 1.7 3km WSW of Anderson Springs, CA
- 1.5 4km W of Cobb, CA
- 1.6 3km NNW of The Geysers, CA
- 2.2 2km NNE of The Geysers, CA
- 1.8 3km SW of Anderson Springs, CA
- 1.9 4km W of Cobb, CA
- 1.6 2km NW of The Geysers, CA
- 1.7 3km N of The Geysers, CA
- 1.7 3km W of Cobb, CA
- 1.9 3km NW of The Geysers, CA
- 1.5 9km NE of Hidden Valley Lake, 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.