Earthquake · reviewed by a seismologist
M 1.7md
Earthquake near Pacifica, CA
No earthquake was likely felt in Pacifica in the 24 hours to 7:14 pm PST (03:14 UTC). The last one was M 2.7, 2 km (1 mi) NE, at 5:17 pm PDT on 28 October 2026, estimated intensity III (weak) in town; 526 felt reports to USGS. Every earthquake near Pacifica
This page: a magnitude 1.7 earthquake was recorded in Pacifica, CA, at 1:28 pm PDT on 28 August 2026 (20:28 UTC), 9.6 km deep.
USGS: 1 km SE of Pacifica, CA
20 km (12 mi) SSW of San Francisco, CA · 10 km (6 mi) WSW of South San Francisco, CA
- When
- 1:28 pm PDT on 28 August 2026 ()
- Where
- in Pacifica, CA · earthquakes near Pacifica
- Magnitude
- M 1.7 (md)
- Depth
- 9.6 km below the surface
- Felt
- no reports yet
- Nearest
- San Mateo County, 23 km SSE
- Nearest mapped fault
- San Andreas fault, 3 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 66 days ago
Earthquake alerts for Pacifica, CA
Get a notification in this browser when USGS records an earthquake near Pacifica, 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 8 km (5 mi) from the epicentre. 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 in town, intensity II · San Bruno 6 km, intensity II · Millbrae 8 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 10 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,000,000× the energy of this one
- Around the size people start to feel M 3.0 92× the energy of this one
- This earthquake M 1.7 about 10 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 11,000 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 · 17 km NNW of this epicentre
- 5.3 The 1957 San Francisco, California Earthquake · 7 km N 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 37.6063, -122.4762. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Mateo County, CA | 23 km (14 mi) | SSE | earthquakes near San Mateo County |
| Alameda County, CA | 50 km (31 mi) | E | earthquakes near Alameda County |
| San Francisco County, CA | 51 km (32 mi) | WNW | earthquakes near San Francisco County |
| Marin County, CA | 55 km (34 mi) | NNW | earthquakes near Marin County |
| Contra Costa County, CA | 58 km (36 mi) | NE | earthquakes near Contra Costa County |
| Santa Cruz County, CA | 78 km (48 mi) | SSE | earthquakes near Santa Cruz County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
54 earthquakes have been recorded within 50 km since this one.
- 1.0 6 km E of Oakland, CA
- 1.7 4 km SSW of Muir Beach, CA
- 1.0 5 km SSW of Los Altos Hills, CA
- 1.5 5 km NNW of Pacifica, CA
- 2.4 4 km SE of San Ramon, CA
- 1.7 1 km SW of San Ramon, CA
- 2.4 2 km SSW of San Ramon, CA
- 1.6 1 km WSW of San Ramon, CA
- 1.4 2 km W of San Ramon, CA
- 1.1 2 km SSW of San Ramon, CA
- 1.8 1 km SW of San Ramon, CA
- 1.6 2 km WSW of Alamo, CA
- 1.8 3 km WSW of San Francisco Zoo, CA
- 1.6 4 km ENE of El Granada, CA
- 1.2 6 km S of Portola Valley, 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.