QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Clayton, CA

No earthquake was likely felt in Clayton in the 24 hours to 10:58 pm PST (06:58 UTC). The last one was M 2.1, 11 km (7 mi) W, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Clayton

This page: a magnitude 1.7 earthquake was recorded 9 km (6 mi) east-southeast of Clayton, CA, at 8:58 pm PDT on 19 April 2023 (03:58 UTC), 13 km deep. 2 people have reported feeling it to USGS.

USGS: 9km ESE of Clayton, CA

8 km (5 mi) SSW of Antioch, CA · 53 km (33 mi) ENE of San Francisco, CA

8:58 pm PDT, Apr 19, 2023 · · 13 km deep · released about 11 lb of TNT

Every earthquake near Clayton Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 10 kmAlameda County 30 kmSolano County 41 kmSan Joaquin County 50 kmSan Mateo County 73 kmSacramento County 74 kmSanta Clara County 78 kmNapa County 79 kmMarin County 81 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
8:58 pm PDT on 19 April 2023 ()
Where
9 km (6 mi) east-southeast of Clayton, CA · earthquakes near Clayton
Magnitude
M 1.7 (md)
Depth
13 km below the surface
Felt
2 reports · strongest reported intensity III
Nearest
Contra Costa County, 10 km W
Nearest mapped fault
Greenville 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 1302 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. In Clayton, 9 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: Antioch, Blackhawk, Brentwood, Pittsburg, Diablo, Oakley.

How big was it?

This earthquake released about 11 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 1,400,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 970,000× the energy of this one
  3. Around the size people start to feel M 3.0 86× the energy of this one
  4. This earthquake M 1.7 about 11 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 4.5 on 2019-10-15 — about 13,000 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

  1. 5.8 The 1980 Livermore, California Earthquake · 10 km SE of this epicentre
  2. 5.7 15 km NE of East Foothills, California · 50 km SSE of this epicentre
  3. 5.4 South of Elmira, California · 44 km N of this epicentre
  4. 5.4 9 km NE of Livermore, California · 21 km SSE of this epicentre
  5. 5.1 11 km E of Blackhawk, California · 12 km SSE 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 37.9118, -121.8372. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 10 km (6 mi) W earthquakes near Contra Costa County
Alameda County, CA 30 km (19 mi) SSW earthquakes near Alameda County
Solano County, CA 41 km (25 mi) NNW earthquakes near Solano County
San Joaquin County, CA 50 km (31 mi) E earthquakes near San Joaquin County
San Mateo County, CA 73 km (45 mi) SW earthquakes near San Mateo County
Sacramento County, CA 74 km (46 mi) NE earthquakes near Sacramento County

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

Aftershocks so far

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

  1. 3.0 2 km NW of Alamo, CA
  2. 1.5 8 km SE of Sunol, CA
  3. 2.2 7 km SW of Brentwood, CA
  4. 2.6 8 km SW of Brentwood, CA
  5. 1.6 5 km E of Vallejo, CA
  6. 1.6 2 km NW of Pittsburg, CA
  7. 1.5 8 km NE of Milpitas, CA
  8. 2.3 9 km NE of Milpitas, CA
  9. 2.2 3 km N of Vallejo, CA
  10. 2.7 3 km N of Piedmont, CA
  11. 1.8 9 km E of Blackhawk, CA
  12. 1.6 6 km E of Vallejo, CA
  13. 1.9 12 km NE of Milpitas, CA
  14. 2.1 3 km NW of Castro Valley, CA
  15. 2.1 5 km ESE of Oakland, 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.