QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4md

Earthquake near Green Valley, CA

No earthquake was likely felt in Green Valley in the 24 hours to 2:14 pm PST (22:14 UTC). The last one was M 1.8, 13 km (8 mi) S, at 11:09 am PST on 4 November 2026, estimated intensity II (weak) in town. Every earthquake near Green Valley

This page: a magnitude 2.4 earthquake was recorded 4 km (3 mi) north-northwest of Green Valley, CA, at 10:42 am PDT on 4 September 2019 (17:42 UTC), 10 km deep. 8 people have reported feeling it to USGS.

USGS: 4km NNW of Green Valley, CA

11 km (7 mi) E of Napa, CA · 60 km (37 mi) NNE of San Francisco, CA

10:42 am PDT, Sep 4, 2019 · · 10 km deep · released about 130 lb of TNT

10 km30 km60 km120 km N Solano County 21 kmNapa County 28 kmContra Costa County 45 kmYolo County 50 kmMarin County 56 kmSonoma County 70 kmAlameda County 75 kmSacramento County 75 kmSan Joaquin County 89 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
10:42 am PDT on 4 September 2019 ()
Where
4 km (3 mi) north-northwest of Green Valley, CA · earthquakes near Green Valley
Magnitude
M 2.4 (md)
Depth
10 km below the surface
Felt
8 reports · strongest reported intensity III
Nearest
Solano County, 21 km E
Nearest mapped fault
Green Valley fault, 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 2617 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 19 km (12 mi) from the epicentre. In Green Valley, 4 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: Napa 9 km, intensity II · Fairfield 13 km, intensity II · Suisun 13 km, intensity II · Vacaville 18 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 130 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 120,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 83,000× the energy of this one
  3. Around the size people start to feel M 3.0 7.4× the energy of this one
  4. This earthquake M 2.4 about 130 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 4.4 on 2018-01-04 — about 870 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 · 14 km SW of this epicentre
  2. 5.4 South of Elmira, California · 24 km E 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 38.2872, -122.1795. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Solano County, CA 21 km (13 mi) E earthquakes near Solano County
Napa County, CA 28 km (17 mi) NNW earthquakes near Napa County
Contra Costa County, CA 45 km (28 mi) SSE earthquakes near Contra Costa County
Yolo County, CA 50 km (31 mi) NNE earthquakes near Yolo County
Marin County, CA 56 km (35 mi) WSW earthquakes near Marin County
Sonoma County, CA 70 km (44 mi) WNW earthquakes near Sonoma County

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

Aftershocks so far

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

  1. 1.6 14km E of Angwin, CA
  2. 1.9 9km NNE of Napa, CA
  3. 2.5 7km WNW of Yountville, CA
  4. 1.6 4km E of Walnut Creek, CA
  5. 2.1 2km NW of Pittsburg, CA
  6. 2.1 2km ENE of Pleasant Hill, CA
  7. 1.7 3km SSW of American Canyon, CA
  8. 2.1 1km ENE of El Cerrito, CA
  9. 1.9 2km SSW of Pleasant Hill, CA
  10. 2.1 1km S of Pleasant Hill, CA
  11. 1.8 5km SSW of Port Costa, CA
  12. 1.9 6km NE of Alamo, CA
  13. 2.0 14km ESE of Angwin, CA
  14. 1.6 14km ESE of Angwin, CA
  15. 1.5 4km N of Angwin, 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.