QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

Earthquake near Cupertino, CA

No earthquake was likely felt in Cupertino in the 24 hours to 3:49 pm PST (23:49 UTC). The last one was M 2.0, 4 km (3 mi) WSW, at 9:23 am PST on 10 November 2026, estimated intensity II (weak) in town; 4 felt reports to USGS. Every earthquake near Cupertino

This page: a magnitude 1.9 earthquake was recorded 4 km (2 mi) west-southwest of Cupertino, CA, at 10:07 pm PDT on 23 September 2023 (05:07 UTC), 6.5 km deep. 3 people have reported feeling it to USGS.

USGS: 4 km WSW of Cupertino, CA

23 km (14 mi) W of San Jose, CA · in Cupertino, CA

10:07 pm PDT, Sep 23, 2023 · · 6.5 km deep · released about 19 lb of TNT

Every earthquake near Cupertino Felt it? Tell USGS Check my area
10 km30 km60 km120 km N San Mateo County 29 kmSanta Cruz County 34 kmSanta Clara County 35 kmAlameda County 40 kmContra Costa County 69 kmSan Francisco County 97 kmStanislaus County 98 kmSan Joaquin County 99 kmMarin County 102 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
10:07 pm PDT on 23 September 2023 ()
Where
4 km (2 mi) west-southwest of Cupertino, CA · earthquakes near Cupertino
Magnitude
M 1.9 (md)
Depth
6.5 km below the surface
Felt
3 reports · strongest reported intensity II
Nearest
San Mateo County, 29 km WNW
Nearest mapped fault
Monte Vista-Shannon 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 1144 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 13 km (8 mi) from the epicentre. In Cupertino, 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: Cupertino 4 km, intensity II · Saratoga 7 km, intensity II · Sunnyvale 7 km, intensity II · Mountain View 8 km, intensity II · Los Altos 9 km, intensity II · Campbell 11 km, intensity II · Santa Clara 11 km, intensity II · Los Gatos 13 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 19 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.9 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 810,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 580,000× the energy of this one
  3. Around the size people start to feel M 3.0 51× the energy of this one
  4. This earthquake M 1.9 about 19 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 5.1 on 2022-10-25 — about 63,000 times the energy of this one.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 35 km SSE of this epicentre
  2. 6.5 Near Morgan Hill, California · 44 km ESE of this epicentre
  3. 6.3 16 km SW of Davenport, California · 49 km SSW of this epicentre
  4. 6.2 Near San Jose, California · 24 km E of this epicentre
  5. 6.2 The 1984 Morgan Hill, California Earthquake · 35 km E 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 37.3103, -122.0713. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Mateo County, CA 29 km (18 mi) WNW earthquakes near San Mateo County
Santa Cruz County, CA 34 km (21 mi) S earthquakes near Santa Cruz County
Santa Clara County, CA 35 km (22 mi) ESE earthquakes near Santa Clara County
Alameda County, CA 40 km (25 mi) NNE earthquakes near Alameda County
Contra Costa County, CA 69 km (43 mi) N earthquakes near Contra Costa County
San Francisco County, CA 97 km (60 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

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

  1. 1.5 15 km E of Alum Rock, CA
  2. 1.5 1 km N of Millbrae, CA
  3. 1.9 2 km NNE of Millbrae, CA
  4. 2.4 7 km ENE of Alum Rock, CA
  5. 2.2 4 km WSW of Cupertino, CA
  6. 2.1 3 km N of San Lorenzo, CA
  7. 2.0 12 km NE of Milpitas, CA
  8. 2.6 16 km E of Seven Trees, CA
  9. 1.5 2 km ESE of Pacifica, CA
  10. 1.7 2 km NNE of Saratoga, CA
  11. 1.6 4 km SW of Hillsborough, CA
  12. 1.7 9 km NNE of Alum Rock, CA
  13. 1.6 4 km SW of Hillsborough, CA
  14. 1.5 2 km NNE of Millbrae, CA
  15. 2.1 10 km SE of Sunol, 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.