QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Antioch, CA

Yes. A magnitude 1.8 earthquake was recorded 5 km (3 mi) WSW of Antioch, CA, at 9:30 pm PDT on 11 August 2016 (04:30 UTC), 17 km deep.

This was on 11 August 2016. The latest near Antioch: M 3.0 on 14 September 2026.

USGS: 5 km WSW of Antioch, California

5 km (3 mi) W of Antioch, CA

9:30 pm PDT, Aug 11, 2016 · · 17 km deep · released about 15 lb of TNT

Every earthquake near Antioch Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 11 kmSolano County 33 kmAlameda County 37 kmSan Joaquin County 52 kmSacramento County 69 kmNapa County 72 kmSan Mateo County 77 kmYolo County 78 kmMarin County 78 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
9:30 pm PDT on 11 August 2016 ()
Where
5 km (3 mi) WSW of Antioch, CA · earthquakes near Antioch
Magnitude
M 1.8 (md)
Depth
17 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 11 km SW
Nearest mapped fault
Greenville fault, 7 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 3532 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 Antioch, 5 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: Pittsburg, Clayton, Bay Point, Oakley, Brentwood, Concord.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
  3. Around the size people start to feel M 3.0 63× the energy of this one
  4. This earthquake M 1.8 about 15 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

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

  1. 6.0 The 2014 South Napa, California Earthquake · 48 km WNW of this epicentre
  2. 5.8 The 1980 Livermore, California Earthquake · 17 km SSE of this epicentre
  3. 5.4 South of Elmira, California · 36 km N of this epicentre
  4. 5.4 9 km NE of Livermore, California · 29 km SSE of this epicentre
  5. 5.1 11 km E of Blackhawk, California · 20 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 37.9790, -121.8570. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 11 km (7 mi) SW earthquakes near Contra Costa County
Solano County, CA 33 km (20 mi) NNW earthquakes near Solano County
Alameda County, CA 37 km (23 mi) S earthquakes near Alameda County
San Joaquin County, CA 52 km (32 mi) E earthquakes near San Joaquin County
Sacramento County, CA 69 km (43 mi) NE earthquakes near Sacramento County
Napa County, CA 72 km (44 mi) NW 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. 1.6 1 km SW of Blackhawk, California
  2. 2.1 0 km SW of Blackhawk, California
  3. 1.5 1 km SW of Blackhawk, California
  4. 2.4 2 km SSE of Berkeley, California
  5. 1.6 0 km SW of Blackhawk, California
  6. 1.9 1 km WSW of Concord, California
  7. 2.3 8 km SE of Livermore, California
  8. 1.6 1 km NW of Acalanes Ridge, California
  9. 1.5 1 km NNW of Piedmont, California
  10. 2.2 0 km NW of Piedmont, California
  11. 2.3 1 km NW of Piedmont, California
  12. 1.6 3 km SSW of Alamo, California
  13. 1.7 1 km SSE of East Richmond Heights, California
  14. 1.7 10 km SW of Brentwood, California
  15. 1.6 6 km SE of Sunol, California

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.