QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Concord, CA

No earthquake was likely felt in Concord in the 24 hours to 5:52 am PST (13:52 UTC). The last one was M 2.1, 5 km (3 mi) SW, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Concord

This page: a magnitude 1.6 earthquake was recorded in Concord, CA, at 10:09 pm PDT on 28 July 2019 (05:09 UTC), 16 km deep.

USGS: 1km W of Concord, CA

in Concord, CA

10:09 pm PDT, Jul 28, 2019 · · 16 km deep · released about 6.8 lb of TNT

Every earthquake near Concord Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 9 kmSolano County 34 kmAlameda County 37 kmMarin County 64 kmNapa County 65 kmSan Joaquin County 66 kmSan Mateo County 69 kmYolo County 80 kmSacramento County 80 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
10:09 pm PDT on 28 July 2019 ()
Where
in Concord, CA · earthquakes near Concord
Magnitude
M 1.6 (md)
Depth
16 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 9 km SE
Nearest mapped fault
Concord fault, 2 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 2662 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. 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: Pleasant Hill, Pacheco, Contra Costa Centre, Waldon, Vine Hill, Walnut Creek.

How big was it?

This earthquake released about 6.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
  3. Around the size people start to feel M 3.0 140× the energy of this one
  4. This earthquake M 1.6 about 6.8 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 4.4 on 2018-01-04 — about 16,000 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 · 37 km NW of this epicentre
  2. 5.8 The 1980 Livermore, California Earthquake · 27 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 · 37 km SE of this epicentre
  5. 5.1 11 km E of Blackhawk, California · 28 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 37.9675, -122.0275. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 9 km (5 mi) SE earthquakes near Contra Costa County
Solano County, CA 34 km (21 mi) NNE earthquakes near Solano County
Alameda County, CA 37 km (23 mi) SSE earthquakes near Alameda County
Marin County, CA 64 km (40 mi) W earthquakes near Marin County
Napa County, CA 65 km (41 mi) NNW earthquakes near Napa County
San Joaquin County, CA 66 km (41 mi) E earthquakes near San Joaquin County

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

Aftershocks so far

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

  1. 1.6 4km NNE of Dublin, CA
  2. 1.7 4km NNE of Dublin, CA
  3. 1.6 4km NNE of Dublin, CA
  4. 1.6 4km N of Dublin, CA
  5. 1.6 4km NNE of Dublin, CA
  6. 2.2 4km N of Dublin, CA
  7. 2.8 4km N of Dublin, CA
  8. 1.8 4km NNE of Dublin, CA
  9. 1.6 4km NNE of Dublin, CA
  10. 2.6 4km NNE of Dublin, CA
  11. 1.6 3km SW of Clayton, CA
  12. 2.3 3km NE of Orinda, CA
  13. 1.6 4km N of Dublin, CA
  14. 1.6 4km NNE of Dublin, CA
  15. 1.6 4km NNE of Dublin, 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.