QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Pacifica, CA

Yes. A magnitude 1.7 earthquake was recorded in Pacifica, CA, at 1:16 pm PDT on 25 September 2016 (20:16 UTC), 8.6 km deep.

This was on 25 September 2016. The latest near Pacifica: M 2.8 on 13 August 2026.

USGS: 1 km NNE of Pacifica, California

18 km (11 mi) SSW of San Francisco, CA · 8 km (5 mi) S of Daly City, CA

1:16 pm PDT, Sep 25, 2016 · · 8.6 km deep · released about 9.6 lb of TNT

Every earthquake near Pacifica Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 25 kmAlameda County 50 kmSan Francisco County 50 kmMarin County 53 kmContra Costa County 57 kmSanta Cruz County 80 kmSanta Clara County 83 kmSolano County 85 kmNapa County 99 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
1:16 pm PDT on 25 September 2016 ()
Where
in Pacifica, CA · earthquakes near Pacifica
Magnitude
M 1.7 (md)
Depth
8.6 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 25 km SSE
Nearest mapped fault
San Andreas fault, 2 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 3531 days ago

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 · Colma 6 km, intensity II · San Bruno 6 km, intensity II · South San Francisco 7 km, intensity II · Millbrae 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 9.6 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.

  1. Mineral, Virginia 2011 M 5.8 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 99× the energy of this one
  4. This earthquake M 1.7 about 9.6 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:

  1. 7.9 The 1906 San Francisco, California Earthquake · 15 km NNW of this epicentre
  2. 5.3 The 1957 San Francisco, California Earthquake · 4 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 37.6268, -122.4778. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Mateo County, CA 25 km (16 mi) SSE earthquakes near San Mateo County
Alameda County, CA 50 km (31 mi) E earthquakes near Alameda County
San Francisco County, CA 50 km (31 mi) WNW earthquakes near San Francisco County
Marin County, CA 53 km (33 mi) NNW earthquakes near Marin County
Contra Costa County, CA 57 km (35 mi) NE earthquakes near Contra Costa County
Santa Cruz County, CA 80 km (50 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

52 earthquakes have been recorded within 50 km since this one.

  1. 1.5 Northern California
  2. 1.8 2 km NE of Pacifica, California
  3. 1.7 1 km ENE of Alamo, California
  4. 1.8 3 km NNW of Castro Valley, California
  5. 2.1 3 km NNW of Castro Valley, California
  6. 1.6 2 km NE of Pacifica, California
  7. 1.7 3 km S of Loyola, California
  8. 1.5 5 km WNW of Broadmoor, California
  9. 2.4 2 km SSE of Berkeley, California
  10. 1.7 2 km S of Loyola, California
  11. 1.6 1 km NW of Acalanes Ridge, California
  12. 2.0 1 km NE of Pacifica, California
  13. 1.8 1 km SSW of Loyola, California
  14. 1.5 1 km NNW of Piedmont, California
  15. 2.2 0 km NW of Piedmont, California

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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.