QuakeIndex

Earthquake · reviewed by a seismologist

M 1.5md

Earthquake near Piedmont, CA

USGS: 2 km N of Piedmont, California

9 km (5 mi) N of Oakland, CA · 6 km (4 mi) ESE of Berkeley, CA

12:34 pm PDT, Oct 20, 2016 · · 5.0 km deep · released about 6.2 lb of TNT

Every earthquake near Piedmont Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 26 kmAlameda County 36 kmSan Mateo County 50 kmMarin County 50 kmSolano County 53 kmSan Francisco County 71 kmNapa County 74 kmSanta Clara County 85 kmSan Joaquin County 85 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
12:34 pm PDT on 20 October 2016 ()
Where
3 km (2 mi) N of Piedmont, CA · earthquakes near Piedmont
Magnitude
M 1.5 (md)
Depth
5.0 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 26 km ENE
Nearest mapped fault
Hayward 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 3521 days ago

A magnitude 1.5 earthquake was recorded 3 km (2 mi) N of Piedmont, CA, at 12:34 pm PDT on 20 October 2016 (19:34 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

Earthquakes near other towns within 30 km: Berkeley, Emeryville, Oakland, Orinda, Albany, Kensington.

How big was it?

This earthquake released about 6.2 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
  3. Around the size people start to feel M 3.0 150× the energy of this one
  4. This earthquake M 1.5 about 6.2 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 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 The 1906 San Francisco, California Earthquake · 30 km WSW of this epicentre
  2. 6.0 The 2014 South Napa, California Earthquake · 41 km N of this epicentre
  3. 5.8 The 1980 Livermore, California Earthquake · 41 km E of this epicentre
  4. 5.4 9 km NE of Livermore, California · 48 km ESE of this epicentre
  5. 5.3 The 1957 San Francisco, California Earthquake · 30 km SW 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 37.8478, -122.2367. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 26 km (16 mi) ENE earthquakes near Contra Costa County
Alameda County, CA 36 km (22 mi) SE earthquakes near Alameda County
San Mateo County, CA 50 km (31 mi) SSW earthquakes near San Mateo County
Marin County, CA 50 km (31 mi) WNW earthquakes near Marin County
Solano County, CA 53 km (33 mi) NNE earthquakes near Solano County
San Francisco County, CA 71 km (44 mi) W earthquakes near San Francisco 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. 1.7 2 km E of Pacifica, California
  2. 1.6 1 km SSW of Concord, California
  3. 1.6 0 km S of Concord, California
  4. 2.2 1 km SW of Concord, California
  5. 2.0 3 km SSE of Piedmont, California
  6. 1.8 1 km ENE of Pacifica, California
  7. 1.7 0 km SSE of Concord, California
  8. 2.4 3 km ENE of Vallejo, California
  9. 2.0 1 km S of Hillsborough, California
  10. 2.0 1 km NW of Ladera, California
  11. 1.5 0 km NE of Woodside, California
  12. 1.8 2 km E of Berkeley, California
  13. 2.6 2 km SSW of Alamo, California
  14. 1.9 1 km E of Pacifica, California
  15. 1.6 2 km E of Pacifica, 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.