QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

Earthquake near San Ramon, CA

Yes. A magnitude 1.9 earthquake was recorded 3 km (2 mi) ESE of San Ramon, CA, at 7:45 pm PDT on 28 September 2016 (02:45 UTC), 8.2 km deep.

This was on 28 September 2016. The latest near San Ramon: M 3.0 on 14 September 2026.

USGS: 2 km ESE of San Ramon, California

in San Ramon, CA · 41 km (26 mi) E of San Francisco, CA

7:45 pm PDT, Sep 28, 2016 · · 8.2 km deep · released about 20 lb of TNT

Every earthquake near San Ramon Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 14 kmContra Costa County 17 kmSan Mateo County 54 kmSolano County 55 kmSan Joaquin County 62 kmSanta Clara County 65 kmMarin County 77 kmSanta Cruz County 84 kmStanislaus County 87 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
7:45 pm PDT on 28 September 2016 ()
Where
3 km (2 mi) ESE of San Ramon, CA · earthquakes near San Ramon
Magnitude
M 1.9 (md)
Depth
8.2 km below the surface
Felt
no reports yet
Nearest
Alameda County, 14 km SSE
Nearest mapped fault
Pleasanton fault, under 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 3531 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 12 km (7 mi) from the epicentre. In San Ramon, 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: San Ramon 3 km, intensity II · Blackhawk 7 km, intensity II · Danville 7 km, intensity II · Diablo 7 km, intensity II · Dublin 7 km, intensity II · Alamo 12 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 20 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 760,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 540,000× the energy of this one
  3. Around the size people start to feel M 3.0 48× the energy of this one
  4. This earthquake M 1.9 about 20 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 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 5.8 The 1980 Livermore, California Earthquake · 18 km ENE of this epicentre
  2. 5.7 15 km NE of East Foothills, California · 40 km SE of this epicentre
  3. 5.5 6 km NNE of East Foothills, California · 40 km SSE of this epicentre
  4. 5.4 9 km NE of Livermore, California · 22 km E of this epicentre
  5. 5.3 The 1957 San Francisco, California Earthquake · 48 km WSW 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 37.7683, -121.9515. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alameda County, CA 14 km (9 mi) SSE earthquakes near Alameda County
Contra Costa County, CA 17 km (10 mi) N earthquakes near Contra Costa County
San Mateo County, CA 54 km (34 mi) SW earthquakes near San Mateo County
Solano County, CA 55 km (34 mi) N earthquakes near Solano County
San Joaquin County, CA 62 km (39 mi) ENE earthquakes near San Joaquin County
Santa Clara County, CA 65 km (40 mi) SSE earthquakes near Santa Clara County

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

Aftershocks so far

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

  1. 1.5 1 km SW of Blackhawk, California
  2. 2.4 2 km SSE of Berkeley, California
  3. 1.6 0 km SW of Blackhawk, California
  4. 2.0 8 km E of East Foothills, California
  5. 1.9 1 km WSW of Concord, California
  6. 2.3 8 km SE of Livermore, California
  7. 1.7 6 km ESE of East Foothills, California
  8. 1.6 1 km NW of Acalanes Ridge, California
  9. 2.0 1 km NE of Pacifica, California
  10. 2.3 7 km NNE of East Foothills, California
  11. 1.5 1 km NNW of Piedmont, California
  12. 2.2 0 km NW of Piedmont, California
  13. 2.3 1 km NW of Piedmont, California
  14. 1.5 2 km NE of Pacifica, California
  15. 1.9 10 km N of East Foothills, 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.