QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near Orinda, CA

No earthquake was likely felt in Orinda in the 24 hours to 4:08 pm PST (00:08 UTC). The last one was M 2.1, 12 km (8 mi) NE, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Orinda

This page: a magnitude 1.5 earthquake was recorded 6 km (4 mi) north-northeast of Orinda, CA, at 9:31 pm PDT on 30 September 2023 (04:31 UTC), less than 1 km deep. 1 person has reported feeling it to USGS.

USGS: 6 km NNE of Orinda, CA

28 km (18 mi) NE of San Francisco, CA · 11 km (7 mi) WNW of Walnut Creek, CA

9:31 pm PDT, Sep 30, 2023 · · 0.4 km deep · released about 5.7 lb of TNT

Every earthquake near Orinda Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 19 kmAlameda County 39 kmSolano County 42 kmMarin County 53 kmSan Mateo County 61 kmNapa County 65 kmSan Joaquin County 78 kmSan Francisco County 80 kmYolo County 86 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
9:31 pm PDT on 30 September 2023 ()
Where
6 km (4 mi) north-northeast of Orinda, CA · earthquakes near Orinda
Magnitude
M 1.5 (md)
Depth
0.4 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Contra Costa County, 19 km E
Nearest mapped fault
Hayward fault, 10 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 636 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 10 km (6 mi) from the epicentre. In Orinda, 6 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: Orinda 6 km, intensity II · Lafayette 7 km, intensity II · Pleasant Hill 9 km, intensity II · Walnut Creek 9 km, intensity II · Pacheco 10 km, intensity II · Martinez 10 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 5.7 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,900,000× the energy of this one
  3. Around the size people start to feel M 3.0 170× the energy of this one
  4. This earthquake M 1.5 about 5.7 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 26,000 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 The 1906 San Francisco, California Earthquake · 40 km WSW of this epicentre
  2. 6.0 The 2014 South Napa, California Earthquake · 34 km NNW of this epicentre
  3. 5.8 The 1980 Livermore, California Earthquake · 36 km ESE of this epicentre
  4. 5.4 South of Elmira, California · 47 km NNE of this epicentre
  5. 5.4 9 km NE of Livermore, California · 45 km ESE 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 37.9340, -122.1648. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 19 km (12 mi) E earthquakes near Contra Costa County
Alameda County, CA 39 km (24 mi) SE earthquakes near Alameda County
Solano County, CA 42 km (26 mi) NNE earthquakes near Solano County
Marin County, CA 53 km (33 mi) WNW earthquakes near Marin County
San Mateo County, CA 61 km (38 mi) SSW earthquakes near San Mateo County
Napa County, CA 65 km (41 mi) NNW earthquakes near Napa County

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

Aftershocks so far

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

  1. 1.7 5 km S of San Ramon, CA
  2. 1.8 5 km S of San Ramon, CA
  3. 1.5 5 km S of San Ramon, CA
  4. 1.7 8 km SSW of Martinez, CA
  5. 2.2 5 km S of San Ramon, CA
  6. 1.6 4 km WSW of Colma, CA
  7. 1.5 1 km N of Millbrae, CA
  8. 1.9 2 km NNE of Millbrae, CA
  9. 1.7 5 km WNW of Byron, CA
  10. 2.2 6 km WNW of San Francisco Zoo, CA
  11. 1.5 6 km WNW of San Francisco Zoo, CA
  12. 2.1 3 km N of San Lorenzo, CA
  13. 1.6 7 km ESE of Santa Venetia, CA
  14. 1.5 2 km ESE of Pacifica, CA
  15. 1.6 4 km SW of Hillsborough, 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.