QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Angwin, CA

No earthquake was likely felt in Angwin in the 24 hours to 1:51 am PST (09:51 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 1.7 earthquake was recorded 14 km (9 mi) east of Angwin, CA, at 10:24 am PST on 15 November 2021 (18:24 UTC), 5.2 km deep.

USGS: 14km E of Angwin, CA

88 km (55 mi) N of San Francisco, CA · 30 km (19 mi) N of Napa, CA

10:24 am PST, Nov 15, 2021 · · 5.2 km deep · released about 9.3 lb of TNT

10 km30 km60 km120 km N Napa County 7 kmYolo County 36 kmSolano County 45 kmSonoma County 56 kmColusa County 68 kmMarin County 70 kmLake County 72 kmSutter County 73 kmContra Costa County 78 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
10:24 am PST on 15 November 2021 ()
Where
14 km (9 mi) east of Angwin, CA · earthquakes near Angwin
Magnitude
M 1.7 (md)
Depth
5.2 km below the surface
Felt
no reports yet
Nearest
Napa County, 7 km SSW
Nearest mapped fault
Hunting Creek-Berryessa fault system, 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 1815 days ago

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 11 km (7 mi) from the epicentre. In Angwin, 14 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: Deer Park, Saint Helena, Yountville, Calistoga, Esparto, Kenwood.

How big was it?

This earthquake released about 9.3 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 100× the energy of this one
  4. This earthquake M 1.7 about 9.3 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 6,900 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

  1. 6.0 The 2014 South Napa, California Earthquake · 39 km S of this epicentre
  2. 5.4 South of Elmira, California · 45 km SE 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 38.5670, -122.2902. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Napa County, CA 7 km (5 mi) SSW earthquakes near Napa County
Yolo County, CA 36 km (22 mi) ENE earthquakes near Yolo County
Solano County, CA 45 km (28 mi) SE earthquakes near Solano County
Sonoma County, CA 56 km (34 mi) W earthquakes near Sonoma County
Colusa County, CA 68 km (42 mi) N earthquakes near Colusa County
Marin County, CA 70 km (43 mi) SW earthquakes near Marin County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

27 earthquakes have been recorded within 50 km since this one.

  1. 2.0 0km NE of The Geysers, CA
  2. 1.7 3km W of Anderson Springs, CA
  3. 1.6 3km E of The Geysers, CA
  4. 1.7 1km NE of The Geysers, CA
  5. 1.6 3km NW of The Geysers, CA
  6. 1.7 4km NNW of Larkfield-Wikiup, CA
  7. 1.6 2km NW of The Geysers, CA
  8. 2.1 8km SW of Calistoga, CA
  9. 2.5 7km SW of Calistoga, CA
  10. 1.7 2km W of Anderson Springs, CA
  11. 1.8 1km NE of The Geysers, CA
  12. 1.6 1km ESE of The Geysers, CA
  13. 1.5 3km ESE of The Geysers, CA
  14. 1.9 2km E of The Geysers, CA
  15. 1.6 2km 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.