Earthquake · reviewed by a seismologist
M 2.2md
Earthquake near Pacheco, CA
No earthquake was likely felt in Pacheco in the 24 hours to 2:33 am PST (10:33 UTC). The last one was M 2.1, 5 km (3 mi) S, at 4:05 am PST on 8 November 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Pacheco
This page: a magnitude 2.2 earthquake was recorded 2 km (1 mi) east of Pacheco, CA, at 9:21 am PST on 8 December 2021 (17:21 UTC), 16 km deep.
USGS: 2km E of Pacheco, CA
in Concord, CA
- When
- 9:21 am PST on 8 December 2021 ()
- Where
- 2 km (1 mi) east of Pacheco, CA · earthquakes near Pacheco
- Magnitude
- M 2.2 (md)
- Depth
- 16 km below the surface
- Felt
- no reports yet
- Nearest
- Contra Costa County, 11 km SE
- Nearest mapped fault
- Concord 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 1794 days ago
Earthquake alerts for Pacheco, CA
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Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 10 km (6 mi) from the epicentre. In Pacheco, 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: Concord in town, intensity II · Pacheco 2 km, intensity II · Pleasant Hill 4 km, intensity II · Martinez 8 km, intensity II · Walnut Creek 9 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 62 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.2 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 240,000× the energy of this one
- Magna, Utah 2020 M 5.7 170,000× the energy of this one
- Around the size people start to feel M 3.0 15× the energy of this one
- This earthquake M 2.2 about 62 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 4.5 on 2019-10-15 — about 2,400 times the energy of this one.
Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:
- 6.0 The 2014 South Napa, California Earthquake · 34 km NW of this epicentre
- 5.8 The 1980 Livermore, California Earthquake · 30 km ESE of this epicentre
- 5.4 South of Elmira, California · 37 km NNE of this epicentre
- 5.4 9 km NE of Livermore, California · 40 km SE of this epicentre
- 5.1 11 km E of Blackhawk, California · 31 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 37.9848, -122.0517. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Contra Costa County, CA | 11 km (7 mi) | SE | earthquakes near Contra Costa County |
| Solano County, CA | 33 km (20 mi) | NNE | earthquakes near Solano County |
| Alameda County, CA | 39 km (25 mi) | SSE | earthquakes near Alameda County |
| Marin County, CA | 61 km (38 mi) | W | earthquakes near Marin County |
| Napa County, CA | 63 km (39 mi) | NNW | earthquakes near Napa County |
| San Joaquin County, CA | 69 km (43 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
49 earthquakes have been recorded within 50 km since this one.
- 1.6 2km ESE of Hayward, CA
- 1.9 4km NNW of Crockett, CA
- 1.8 3km W of American Canyon, CA
- 1.5 8km WSW of Brentwood, CA
- 2.3 4km SSE of Vallejo, CA
- 2.8 1km ENE of El Cerrito, CA
- 1.8 5km ESE of Blackhawk, CA
- 1.6 5km E of Vallejo, CA
- 2.0 1km NW of Concord, CA
- 1.6 2km NNE of Danville, CA
- 2.3 5km E of Blackhawk, CA
- 1.6 4km E of South San Francisco, CA
- 1.9 3km ESE of Pacheco, CA
- 1.7 2km SSW of Blackhawk, CA
- 1.6 2km NE of Union City, 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
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.