QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

Earthquake near Angwin, CA

No earthquake was likely felt in Angwin in the 24 hours to 6:29 am PST (14:29 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 1.9 earthquake was recorded 13 km (8 mi) east of Angwin, CA, at 5:52 am PDT on 8 September 2019 (12:52 UTC), 4.2 km deep.

USGS: 13km E of Angwin, CA

87 km (54 mi) N of San Francisco, CA · 29 km (18 mi) N of Napa, CA

5:52 am PDT, Sep 8, 2019 · · 4.2 km deep · released about 18 lb of TNT

10 km30 km60 km120 km N Napa County 6 kmYolo County 37 kmSolano County 45 kmSonoma County 55 kmMarin County 69 kmColusa County 69 kmLake County 72 kmSutter County 74 kmContra Costa County 77 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
5:52 am PDT on 8 September 2019 ()
Where
13 km (8 mi) east of Angwin, CA · earthquakes near Angwin
Magnitude
M 1.9 (md)
Depth
4.2 km below the surface
Felt
no reports yet
Nearest
Napa County, 6 km SSW
Nearest mapped fault
Hunting Creek-Berryessa fault system, 4 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 2612 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 14 km (9 mi) from the epicentre. In Angwin, 13 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: Angwin 13 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 18 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 840,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 600,000× the energy of this one
  3. Around the size people start to feel M 3.0 53× the energy of this one
  4. This earthquake M 1.9 about 18 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 3,600 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 · 38 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 38.5583, -122.2988. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Napa County, CA 6 km (4 mi) SSW earthquakes near Napa County
Yolo County, CA 37 km (23 mi) ENE earthquakes near Yolo County
Solano County, CA 45 km (28 mi) SE earthquakes near Solano County
Sonoma County, CA 55 km (34 mi) W earthquakes near Sonoma County
Marin County, CA 69 km (43 mi) SW earthquakes near Marin County
Colusa County, CA 69 km (43 mi) N earthquakes near Colusa County

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

Aftershocks so far

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

  1. 2.8 3km NE of The Geysers, CA
  2. 1.8 2km ENE of The Geysers, CA
  3. 2.1 3km SE of The Geysers, CA
  4. 2.1 3km SE of The Geysers, CA
  5. 1.7 3km NW of The Geysers, CA
  6. 1.7 2km ESE of The Geysers, CA
  7. 1.6 3km SSW of Cobb, CA
  8. 1.6 3km SW of Anderson Springs, CA
  9. 1.6 4km SSE of The Geysers, CA
  10. 1.7 3km SW of Anderson Springs, CA
  11. 1.7 6km W of Yountville, CA
  12. 1.6 3km NW of The Geysers, CA
  13. 1.6 12km ESE of Hidden Valley Lake, CA
  14. 2.8 2km N of The Geysers, CA
  15. 1.6 2km NW 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.