Earthquake · reviewed by a seismologist
M 1.6md
Earthquake near South San Francisco, CA
No earthquake was likely felt in South San Francisco in the 24 hours to 6:06 am PST (14:06 UTC). The last one was M 2.7, 6 km (4 mi) WSW, at 5:17 pm PDT on 28 October 2026, estimated intensity III (weak) in town; 526 felt reports to USGS. Every earthquake near South San Francisco
This page: a magnitude 1.6 earthquake was recorded 4 km (3 mi) east of South San Francisco, CA, at 1:35 pm PST on 28 February 2022 (21:35 UTC), 9.9 km deep. 1 person has reported feeling it to USGS.
USGS: 4km E of South San Francisco, CA
15 km (9 mi) SSE of San Francisco, CA · in South San Francisco, CA
- When
- 1:35 pm PST on 28 February 2022 ()
- Where
- 4 km (3 mi) east of South San Francisco, CA · earthquakes near South San Francisco
- Magnitude
- M 1.6 (md)
- Depth
- 9.9 km below the surface
- Felt
- 1 report · strongest reported intensity I
- Nearest
- San Mateo County, 26 km S
- Nearest mapped fault
- Serra fault, 7 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 1717 days ago
Earthquake alerts for South San Francisco, CA
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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 6 km (4 mi) from the epicentre. In South San Francisco, 4 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: South San Francisco 4 km, intensity II · San Bruno 5 km, intensity II · Millbrae 6 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 8.7 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 1,700,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,200,000× the energy of this one
- Around the size people start to feel M 3.0 110× the energy of this one
- This earthquake M 1.6 about 8.7 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 17,000 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 · 20 km WNW of this epicentre
- 5.3 The 1957 San Francisco, California Earthquake · 11 km W 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 37.6512, -122.3620. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Mateo County, CA | 26 km (16 mi) | S | earthquakes near San Mateo County |
| Alameda County, CA | 40 km (25 mi) | E | earthquakes near Alameda County |
| Contra Costa County, CA | 47 km (29 mi) | NE | earthquakes near Contra Costa County |
| Marin County, CA | 56 km (35 mi) | NW | earthquakes near Marin County |
| San Francisco County, CA | 60 km (37 mi) | W | earthquakes near San Francisco County |
| Santa Clara County, CA | 76 km (47 mi) | SE | earthquakes near Santa Clara County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
46 earthquakes have been recorded within 50 km since this one.
- 1.8 3km ESE of Pacifica, CA
- 1.8 7km SSE of Portola Valley, CA
- 1.7 1km W of Pacifica, CA
- 2.2 1km WSW of Pacifica, CA
- 2.5 4km SSE of Rodeo, CA
- 1.8 2km SSE of Alamo, CA
- 2.2 3km W of Orinda, CA
- 2.3 3km W of Orinda, CA
- 1.6 3km E of Oakland, CA
- 1.5 7km ESE of Fremont, CA
- 1.6 6km SSE of Portola Valley, CA
- 2.5 6km SSE of Portola Valley, CA
- 1.9 8km S of Sunol, CA
- 1.9 1km W of Martinez, CA
- 1.5 2km NE of San Ramon, 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.