Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Angwin, CA
No earthquake was likely felt in Angwin in the 24 hours to 9:04 am PST (17:04 UTC). The last one was M 1.6, in Angwin, at 11:57 pm PDT on 10 October 2026, estimated intensity II (weak) in town. Every earthquake near Angwin
This page: a magnitude 1.6 earthquake was recorded 15 km (9 mi) north-northeast of Angwin, CA, at 3:58 am PDT on 17 May 2021 (10:58 UTC), 8.9 km deep.
USGS: 15km NNE of Angwin, CA
39 km (24 mi) NE of Santa Rosa, CA · 103 km (64 mi) N of San Francisco, CA
- When
- 3:58 am PDT on 17 May 2021 ()
- Where
- 15 km (9 mi) north-northeast of Angwin, CA · earthquakes near Angwin
- Magnitude
- M 1.6 (md)
- Depth
- 8.9 km below the surface
- Felt
- no reports yet
- Nearest
- Napa County, 23 km SSE
- Nearest mapped fault
- Hunting Creek-Berryessa fault system, under 1 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 2002 days ago
Earthquake alerts for Angwin, CA
Get a notification in this browser when USGS records an earthquake near Angwin, 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 7 km (4 mi) from the epicentre. In Angwin, 15 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: Hidden Valley Lake, Middletown, Deer Park, Calistoga, Saint Helena, Lower Lake.
How big was it?
This earthquake released about 7.8 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 1,900,000× 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 3.0 120× the energy of this one
- This earthquake M 1.6 about 7.8 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 130,000 times the energy of this one.
Before 2016, the USGS record since 1900 lists no earthquake of M5 or more within 50 km.
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 38.7037, -122.4098. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Napa County, CA | 23 km (14 mi) | SSE | earthquakes near Napa County |
| Yolo County, CA | 44 km (27 mi) | E | earthquakes near Yolo County |
| Sonoma County, CA | 49 km (30 mi) | WSW | earthquakes near Sonoma County |
| Lake County, CA | 54 km (33 mi) | NNW | earthquakes near Lake County |
| Colusa County, CA | 55 km (34 mi) | NNE | earthquakes near Colusa County |
| Solano County, CA | 63 km (39 mi) | SE | earthquakes near Solano County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
60 earthquakes have been recorded within 50 km since this one.
- 4.0 7km WNW of The Geysers, CA
- 1.8 8km W of Cobb, CA
- 1.5 4km W of Cobb, CA
- 1.5 7km NW of The Geysers, CA
- 1.6 3km NNW of The Geysers, CA
- 1.5 7km NW of The Geysers, CA
- 1.7 7km W of Cobb, CA
- 1.7 6km NW of The Geysers, CA
- 2.4 5km NW of The Geysers, CA
- 2.2 2km NNE of The Geysers, CA
- 1.8 3km SW of Anderson Springs, CA
- 2.1 6km WNW of The Geysers, CA
- 1.9 6km NW of The Geysers, CA
- 1.6 6km NW of The Geysers, CA
- 1.9 4km W of Cobb, 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.