QuakeIndex

Earthquake · reviewed by a seismologist

M 3.5mw

2 km NNE of Byron, CA

· 8.2 km deep · released about 2.6 tons of TNT

Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 28 kmSan Joaquin County 32 kmAlameda County 37 kmSolano County 50 kmStanislaus County 66 kmSacramento County 67 kmSanta Clara County 74 kmSan Mateo County 84 kmYolo County 91 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
Magnitude
M 3.5 (mw)
Depth
8.2 km below the surface
Felt
589 reports · strongest reported intensity IV
Measured shaking
intensity IV (ShakeMap)
Nearest
Contra Costa County, 28 km W
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 794 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 589 people have reported feeling it to USGS.

How big was it?

This earthquake released about 2.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

  1. Northridge, California 1994 M 6.7 65,000× the energy of this one
  2. Mineral, Virginia 2011 M 5.8 2,900× the energy of this one
  3. Magna, Utah 2020 M 5.7 2,100× the energy of this one
  4. This earthquake M 3.5 about 2.6 tons of TNT
  5. Around the size people start to feel M 3.0 this one released 5.4× more

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.

Where

Epicentre 37.8887, -121.6303. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection
Contra Costa County, CA 28 km (18 mi) E of here earthquakes near Contra Costa County
San Joaquin County, CA 32 km (20 mi) W of here earthquakes near San Joaquin County
Alameda County, CA 37 km (23 mi) NE of here earthquakes near Alameda County
Solano County, CA 50 km (31 mi) SSE of here earthquakes near Solano County
Stanislaus County, CA 66 km (41 mi) WNW of here earthquakes near Stanislaus County
Sacramento County, CA 67 km (42 mi) SSW of here earthquakes near Sacramento County

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

Aftershocks so far

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

  1. 1.6 13 km SSE of Livermore, CA
  2. 2.5 13 km SSE of Livermore, CA
  3. 1.6 5 km NNE of Fairview, CA
  4. 1.7 7 km SW of Brentwood, CA
  5. 1.5 2 km SSE of Pacheco, CA
  6. 3.0 10 km E of Blackhawk, CA
  7. 1.8 2 km WNW of Concord, CA
  8. 1.6 8 km NNE of Bay Point, CA
  9. 2.0 2 km NNE of Pleasant Hill, CA
  10. 1.7 10 km WSW of Mountain House, CA
  11. 2.8 2 km SSE of Pacheco, CA
  12. 2.3 7 km SSE of Elmira, CA
  13. 1.8 7 km SE of Fremont, CA
  14. 2.1 4 km E of Union City, CA
  15. 1.8 7 km SSE of Sunol, 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.

For this area

The largest earthquake within 50 km in our catalogue was M 4.5 on 2019-10-15 — it released about 29 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.