QuakeIndex

Earthquake · reviewed by a seismologist

M 1.8md

Earthquake near Highlands-Baywood Park, CA

No earthquake was likely felt in Highlands-Baywood Park in the 24 hours to 10:37 pm PST (06:37 UTC). The last one was M 2.7, 16 km (10 mi) NW, at 5:17 pm PDT on 28 October 2026, estimated intensity II (weak) in town; 526 felt reports to USGS. Every earthquake near Highlands-Baywood Park

This page: a magnitude 1.8 earthquake was recorded 4 km (3 mi) south-southeast of Highlands-Baywood Park, CA, at 9:40 pm PDT on 25 May 2023 (04:40 UTC), 14 km deep.

USGS: 4km SSE of Highlands-Baywood Park, CA

8 km (5 mi) S of San Mateo, CA · 34 km (21 mi) SSE of San Francisco, CA

9:40 pm PDT, May 25, 2023 · · 14 km deep · released about 17 lb of TNT

10 km30 km60 km120 km N San Mateo County 9 kmAlameda County 41 kmContra Costa County 59 kmSanta Cruz County 60 kmSanta Clara County 64 kmSan Francisco County 68 kmMarin County 73 kmSolano County 93 kmSan Joaquin County 105 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
9:40 pm PDT on 25 May 2023 ()
Where
4 km (3 mi) south-southeast of Highlands-Baywood Park, CA · earthquakes near Highlands-Baywood Park
Magnitude
M 1.8 (md)
Depth
14 km below the surface
Felt
no reports yet
Nearest
San Mateo County, 9 km SSW
Nearest mapped fault
San Andreas fault, under 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 1266 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 4 km (2 mi) from the epicentre. In Highlands-Baywood Park, 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.

Earthquakes near other towns within 30 km: Emerald Lake Hills, Belmont, San Carlos, Redwood City, San Mateo, Woodside.

How big was it?

This earthquake released about 17 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 870,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 620,000× the energy of this one
  3. Around the size people start to feel M 3.0 55× the energy of this one
  4. This earthquake M 1.8 about 17 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 6,500 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 7.9 The 1906 San Francisco, California Earthquake · 35 km NNW of this epicentre
  2. 5.8 7 km NNW of Boulder Creek, California · 37 km SSE of this epicentre
  3. 5.5 Santa Cruz Mountains, California · 45 km SE of this epicentre
  4. 5.5 6 km NNE of East Foothills, California · 49 km E of this epicentre
  5. 5.3 The 1957 San Francisco, California Earthquake · 24 km NW 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 37.4853, -122.3273. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Mateo County, CA 9 km (5 mi) SSW earthquakes near San Mateo County
Alameda County, CA 41 km (25 mi) ENE earthquakes near Alameda County
Contra Costa County, CA 59 km (36 mi) NE earthquakes near Contra Costa County
Santa Cruz County, CA 60 km (37 mi) SSE earthquakes near Santa Cruz County
Santa Clara County, CA 64 km (39 mi) ESE earthquakes near Santa Clara County
San Francisco County, CA 68 km (42 mi) WNW earthquakes near San Francisco County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

  1. 2.0 7 km NW of San Francisco Zoo, CA
  2. 1.9 3 km ESE of South San Francisco, CA
  3. 1.7 4 km WSW of Cupertino, CA
  4. 2.1 4 km WSW of Cupertino, CA
  5. 1.8 4 km WSW of Cupertino, CA
  6. 2.8 4 km WSW of Cupertino, CA
  7. 1.8 4 km WSW of Cupertino, CA
  8. 1.6 5 km WSW of Cupertino, CA
  9. 1.9 4 km WSW of Cupertino, CA
  10. 2.9 4 km WSW of Cupertino, CA
  11. 2.0 1 km E of Pacifica, CA
  12. 2.3 1 km E of Pacifica, CA
  13. 2.4 3 km WSW of Half Moon Bay, CA
  14. 1.5 4 km ESE of Pacifica, CA
  15. 1.6 9 km SW of Loyola, 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

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