QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Walnut Creek, CA

USGS: 2 km SSE of North Gate, California

5 km (3 mi) ESE of Walnut Creek, CA · 40 km (25 mi) ENE of San Francisco, CA

5:03 pm PST, Dec 20, 2016 · · 10 km deep · released about 15 lb of TNT

Every earthquake near Walnut Creek Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Contra Costa County 5 kmAlameda County 27 kmSolano County 43 kmSan Mateo County 62 kmSan Joaquin County 63 kmMarin County 69 kmNapa County 76 kmSanta Clara County 78 kmSacramento 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
5:03 pm PST on 20 December 2016 ()
Where
7 km (5 mi) ESE of Walnut Creek, CA · earthquakes near Walnut Creek
Magnitude
M 1.8 (md)
Depth
10 km below the surface
Felt
no reports yet
Nearest
Contra Costa County, 5 km NE
Nearest mapped fault
Calaveras fault, 6 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 1.8 earthquake was recorded 7 km (5 mi) ESE of Walnut Creek, CA, at 5:03 pm PST on 20 December 2016 (01:03 UTC). This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

Earthquakes near other towns within 30 km: Alamo, Diablo, Danville, Waldon, Saranap, Clayton.

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 6 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.0 The 2014 South Napa, California Earthquake · 47 km NW of this epicentre
  2. 5.8 The 1980 Livermore, California Earthquake · 20 km ESE of this epicentre
  3. 5.4 South of Elmira, California · 47 km N of this epicentre
  4. 5.4 9 km NE of Livermore, California · 29 km ESE of this epicentre
  5. 5.3 The 1957 San Francisco, California Earthquake · 50 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 37.8815, -121.9858. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Contra Costa County, CA 5 km (3 mi) NE earthquakes near Contra Costa County
Alameda County, CA 27 km (17 mi) SSE earthquakes near Alameda County
Solano County, CA 43 km (27 mi) N earthquakes near Solano County
San Mateo County, CA 62 km (39 mi) SSW earthquakes near San Mateo County
San Joaquin County, CA 63 km (39 mi) E earthquakes near San Joaquin County
Marin County, CA 69 km (43 mi) WNW earthquakes near Marin County

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

Aftershocks so far

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

  1. 1.5 5 km ESE of Fremont, California
  2. 2.3 9 km ENE of Blackhawk, California
  3. 2.4 4 km ESE of Clayton, California
  4. 1.9 1 km W of Diablo, California
  5. 1.6 1 km W of Diablo, California
  6. 1.5 0 km SE of Green Valley, California
  7. 1.6 3 km NE of Vallejo, California
  8. 1.8 10 km NNE of East Foothills, California
  9. 1.7 1 km W of Diablo, California
  10. 2.0 5 km WSW of Martinez, California
  11. 1.7 4 km S of Pittsburg, California
  12. 1.5 1 km S of Livermore, California
  13. 2.1 8 km N of East Foothills, California
  14. 2.8 8 km SE of Livermore, California
  15. 1.6 2 km ESE of Waldon, 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.