Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near Colma, CA
No earthquake was likely felt in Colma in the 24 hours to 7:51 am PST (15:51 UTC). The last one was M 2.7, 6 km (4 mi) S, at 5:17 pm PDT on 28 October 2026, estimated intensity III (weak) in town; 526 felt reports to USGS. Every earthquake near Colma
This page: a magnitude 1.6 earthquake was recorded 6 km (4 mi) west-southwest of Colma, CA, at 7:01 am PST on 8 December 2021 (15:01 UTC), 8.9 km deep. 2 people have reported feeling it to USGS.
USGS: 6km WSW of Colma, CA
16 km (10 mi) SW of San Francisco, CA · 7 km (4 mi) SW of Daly City, CA
- When
- 7:01 am PST on 8 December 2021 ()
- Where
- 6 km (4 mi) west-southwest of Colma, CA · earthquakes near Colma
- Magnitude
- M 1.6 (md)
- Depth
- 8.9 km below the surface
- Felt
- 2 reports · strongest reported intensity I
- Nearest
- San Mateo County, 30 km SSE
- Nearest mapped fault
- San Andreas fault, 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 Colma, CA
Get a notification in this browser when USGS records an earthquake near Colma, CA. No account or email needed.
Alerts are on for .
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 7 km (4 mi) from the epicentre. In Colma, 6 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: Pacifica 6 km, intensity II · Daly City 7 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 8.1 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.
- Mineral, Virginia 2011 M 5.8 1,900,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,300,000× the energy of this one
- Around the size people start to feel M 3.0 120× the energy of this one
- This earthquake M 1.6 about 8.1 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 4.4 on 2018-01-04 — about 14,000 times the energy of this one.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 7.9 The 1906 San Francisco, California Earthquake · 10 km NNW of this epicentre
- 5.3 The 1957 San Francisco, California Earthquake · 4 km E 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 37.6610, -122.5228. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Mateo County, CA | 30 km (19 mi) | SSE | earthquakes near San Mateo County |
| San Francisco County, CA | 45 km (28 mi) | W | earthquakes near San Francisco County |
| Marin County, CA | 48 km (30 mi) | NNW | earthquakes near Marin County |
| Alameda County, CA | 54 km (33 mi) | E | earthquakes near Alameda County |
| Contra Costa County, CA | 58 km (36 mi) | ENE | earthquakes near Contra Costa County |
| Solano County, CA | 85 km (53 mi) | NE | earthquakes near Solano 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.
- 2.1 1km E of Piedmont, CA
- 2.0 4km SSE of Highlands-Baywood Park, CA
- 1.9 2km N of Castro Valley, CA
- 1.9 5km ESE of Moraga, CA
- 1.6 4km SW of San Ramon, CA
- 1.6 4km SW of San Ramon, CA
- 1.6 7km S of Muir Beach, CA
- 1.8 3km SW of San Francisco Zoo, CA
- 2.1 3km NE of Berkeley, CA
- 2.0 2km E of Hayward, CA
- 1.6 2km E of Hayward, CA
- 1.6 2km ESE of Hayward, CA
- 2.8 1km ENE of El Cerrito, CA
- 1.7 6km WSW of Daly City, CA
- 1.6 4km E of South San Francisco, 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.