Earthquake · reviewed by a seismologist
M 1.5md
Earthquake near Millbrae, CA
No earthquake was likely felt in Millbrae in the 24 hours to 10:52 pm PST (06:52 UTC). The last one was M 2.7, 8 km (5 mi) WNW, at 5:17 pm PDT on 28 October 2026, estimated intensity III (weak) in town; 526 felt reports to USGS. Every earthquake near Millbrae
This page: a magnitude 1.5 earthquake was recorded 3 km (2 mi) north-northeast of Millbrae, CA, at 8:08 am PDT on 22 October 2017 (15:08 UTC), 12 km deep.
USGS: 2 km NNE of Millbrae, California
18 km (11 mi) SSE of San Francisco, CA · in South San Francisco, CA
- When
- 8:08 am PDT on 22 October 2017 ()
- Where
- 3 km (2 mi) north-northeast of Millbrae, CA · earthquakes near Millbrae
- Magnitude
- M 1.5 (md)
- Depth
- 12 km below the surface
- Felt
- no reports yet
- Nearest
- San Mateo County, 23 km S
- Nearest mapped fault
- Serra fault, 4 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 3305 days ago
Earthquake alerts for Millbrae, 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 it was probably too small to be felt, even directly above it. In Millbrae, 3 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.
Earthquakes near other towns within 30 km: San Bruno, Burlingame, South San Francisco, Hillsborough, Brisbane, San Mateo.
How big was it?
This earthquake released about 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
- Around the size people start to feel M 3.0 160× the energy of this one
- This earthquake M 1.5 about 5.9 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 2 earthquakes of M5 or more within 50 km:
- 7.9 The 1906 San Francisco, California Earthquake · 21 km NW of this epicentre
- 5.3 The 1957 San Francisco, California Earthquake · 11 km WNW 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 37.6210, -122.3733. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Mateo County, CA | 23 km (14 mi) | S | earthquakes near San Mateo County |
| Alameda County, CA | 41 km (25 mi) | E | earthquakes near Alameda County |
| Contra Costa County, CA | 50 km (31 mi) | NE | earthquakes near Contra Costa County |
| Marin County, CA | 58 km (36 mi) | NW | earthquakes near Marin County |
| San Francisco County, CA | 59 km (37 mi) | WNW | earthquakes near San Francisco County |
| Santa Clara County, CA | 75 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
58 earthquakes have been recorded within 50 km since this one.
- 2.5 2km W of Diablo, CA
- 2.8 2km NW of Diablo, CA
- 2.4 2km WNW of Diablo, CA
- 1.6 2km WNW of Diablo, CA
- 3.0 2km WNW of Diablo, CA
- 1.8 2km WNW of Diablo, CA
- 2.5 2km WNW of Diablo, CA
- 2.2 2km WNW of Diablo, CA
- 1.7 2km W of Diablo, CA
- 1.5 2km W of Diablo, CA
- 2.1 2km WNW of Diablo, CA
- 1.5 2km W of Diablo, CA
- 2.1 2km WNW of Diablo, CA
- 1.5 2km WNW of Diablo, CA
- 2.4 2km WNW of Diablo, 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.