QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Union City, CA

Yes. A magnitude 1.6 earthquake was recorded 2 km (2 mi) ESE of Union City, CA, at 5:21 pm PDT on 8 May 2016 (00:21 UTC), 5.7 km deep.

This was on 8 May 2016. The latest near Union City: M 2.5 on 19 September 2026.

USGS: 2 km E of Union City, California

in Union City, CA · 36 km (23 mi) NNW of San Jose, CA

5:21 pm PDT, May 8, 2016 · · 5.7 km deep · released about 6.6 lb of TNT

Every earthquake near Union City Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Alameda County 9 kmContra Costa County 37 kmSan Mateo County 39 kmSanta Clara County 49 kmSanta Cruz County 64 kmSan Joaquin County 74 kmSolano County 75 kmMarin 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
5:21 pm PDT on 8 May 2016 ()
Where
2 km (2 mi) ESE of Union City, CA · earthquakes near Union City
Magnitude
M 1.6 (md)
Depth
5.7 km below the surface
Felt
no reports yet
Nearest
Alameda County, 9 km NE
Nearest mapped fault
Hayward fault, 4 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, people at rest would likely notice it out to about 9 km (6 mi) from the epicentre. In Union City, 2 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: Union City 2 km, intensity II · Fremont 5 km, intensity II · Newark 8 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 6.6 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 2,300,000× 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 6.6 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 15 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 Near San Jose, California · 37 km SSE of this epicentre
  2. 6.2 The 1984 Morgan Hill, California Earthquake · 42 km SE of this epicentre
  3. 6.1 Near San Jose, California · 47 km SSE of this epicentre
  4. 5.8 7 km NNW of Boulder Creek, California · 47 km SSW of this epicentre
  5. 5.8 The 1980 Livermore, California Earthquake · 34 km NE 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 37.5915, -121.9920. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Alameda County, CA 9 km (6 mi) NE earthquakes near Alameda County
Contra Costa County, CA 37 km (23 mi) N earthquakes near Contra Costa County
San Mateo County, CA 39 km (24 mi) WSW earthquakes near San Mateo County
Santa Clara County, CA 49 km (30 mi) SSE earthquakes near Santa Clara County
Santa Cruz County, CA 64 km (40 mi) S earthquakes near Santa Cruz County
San Joaquin County, CA 74 km (46 mi) ENE earthquakes near San Joaquin County

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

Aftershocks so far

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

  1. 2.0 2 km WSW of Blackhawk, California
  2. 1.8 3 km S of Loyola, California
  3. 1.6 2 km ENE of Pacifica, California
  4. 1.7 1 km NNW of Ashland, California
  5. 1.7 1 km SSE of Noe Valley, California
  6. 1.9 4 km SW of Dublin, California
  7. 2.6 2 km S of Diablo, California
  8. 1.5 2 km S of Loyola, California
  9. 1.8 5 km WSW of Antioch, California
  10. 2.0 1 km NE of Pacifica, California
  11. 1.6 5 km E of Alameda, California
  12. 1.5 3 km S of Loyola, California
  13. 1.9 6 km ENE of East Foothills, California
  14. 2.1 11 km SE of Sunol, California
  15. 1.5 5 km E of Alameda, 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.