QuakeIndex

Earthquake · reviewed by a seismologist

M 2.6md

Earthquake near Pleasant Hill, CA

No earthquake was likely felt in Pleasant Hill in the 24 hours to 1:39 am PST (09:39 UTC). The last one was M 2.1, in Pleasant Hill, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Pleasant Hill

This page: a magnitude 2.6 earthquake was recorded 3 km (2 mi) north-northeast of Pleasant Hill, CA, at 6:24 pm PDT on 31 October 2023 (01:24 UTC), 15 km deep. 37 people have reported feeling it to USGS.

USGS: 3 km NNE of Pleasant Hill, CA

in Concord, CA

6:24 pm PDT, Oct 31, 2023 · · 15 km deep · released about 240 lb of TNT

Every earthquake near Pleasant Hill Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 10 kmSolano County 35 kmAlameda County 38 kmMarin County 62 kmNapa County 65 kmSan Mateo County 68 kmSan Joaquin County 68 kmYolo County 80 kmSacramento County 82 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
6:24 pm PDT on 31 October 2023 ()
Where
3 km (2 mi) north-northeast of Pleasant Hill, CA · earthquakes near Pleasant Hill
Magnitude
M 2.6 (md)
Depth
15 km below the surface
Felt
37 reports · strongest reported intensity IV
Nearest
Contra Costa County, 10 km ESE
Nearest mapped fault
Concord fault, 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 669 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 18 km (11 mi) from the epicentre. In Pleasant Hill, 3 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: Concord in town, intensity II · Pleasant Hill 3 km, intensity II · Pacheco 3 km, intensity II · Walnut Creek 7 km, intensity II · Martinez 9 km, intensity II · Lafayette 11 km, intensity II · Benicia 13 km, intensity II · Alamo 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 240 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 63,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 45,000× the energy of this one
  3. Around the size people start to feel M 3.0 4× the energy of this one
  4. This earthquake M 2.6 about 240 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 620 times the energy of this one.

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

  1. 6.0 The 2014 South Napa, California Earthquake · 36 km NW of this epicentre
  2. 5.8 The 1980 Livermore, California Earthquake · 28 km ESE of this epicentre
  3. 5.4 South of Elmira, California · 39 km NNE of this epicentre
  4. 5.4 9 km NE of Livermore, California · 39 km SE of this epicentre
  5. 5.1 11 km E of Blackhawk, California · 30 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 37.9687, -122.0477. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 10 km (6 mi) ESE earthquakes near Contra Costa County
Solano County, CA 35 km (21 mi) NNE earthquakes near Solano County
Alameda County, CA 38 km (23 mi) SSE earthquakes near Alameda County
Marin County, CA 62 km (38 mi) W earthquakes near Marin County
Napa County, CA 65 km (40 mi) NNW earthquakes near Napa County
San Mateo County, CA 68 km (42 mi) SSW earthquakes near San Mateo County

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

Aftershocks so far

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

  1. 1.6 2 km E of Hayward, CA
  2. 1.5 7 km ENE of Vallejo, CA
  3. 2.2 8 km W of Brentwood, CA
  4. 1.6 3 km E of Oakland, CA
  5. 2.2 6 km S of Alameda, CA
  6. 1.6 6 km S of Alameda, CA
  7. 1.5 6 km E of Santa Venetia, CA
  8. 1.6 1 km SSE of Pacheco, CA
  9. 1.5 2 km N of Pleasant Hill, CA
  10. 1.6 2 km ENE of Oakland, CA
  11. 1.8 0 km SW of Crockett, CA
  12. 1.7 8 km NW of Bayview-Montalvin, CA
  13. 2.0 3 km SSE of Vacaville, CA
  14. 1.8 1 km N of Pacheco, CA
  15. 1.6 6 km SSE of Moraga, 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.