QuakeIndex

Earthquake · reviewed by a seismologist

M 1.9md

Earthquake near Boulder Creek, CA

No earthquake was likely felt in Boulder Creek in the 24 hours to 4:50 am PST (12:50 UTC). The last one was M 2.3, 12 km (7 mi) E, at 2:58 am PDT on 9 October 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Boulder Creek

This page: a magnitude 1.9 earthquake was recorded 9 km (6 mi) north of Boulder Creek, CA, at 10:22 pm PDT on 1 April 2026 (05:22 UTC), 11 km deep. 36 people have reported feeling it to USGS.

USGS: 9 km N of Boulder Creek, CA

28 km (17 mi) WSW of San Jose, CA · 13 km (8 mi) SSW of Cupertino, CA

10:22 pm PDT, Apr 1, 2026 · · 11 km deep · released about 23 lb of TNT

Every earthquake near Boulder Creek Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Santa Cruz County 24 kmSan Mateo County 32 kmSanta Clara County 38 kmAlameda County 52 kmContra Costa County 80 kmSan Francisco County 99 kmStanislaus County 106 kmMarin County 109 kmSan Joaquin County 109 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
10:22 pm PDT on 1 April 2026 ()
Where
9 km (6 mi) north of Boulder Creek, CA · earthquakes near Boulder Creek
Magnitude
M 1.9 (md)
Depth
11 km below the surface
Felt
36 reports · strongest reported intensity I
Nearest
Santa Cruz County, 24 km SSE
Nearest mapped fault
Butano 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 217 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 10 km (6 mi) from the epicentre. In Boulder Creek, 9 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: Boulder Creek 9 km, intensity II · Saratoga 10 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 23 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 5.8 660,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 470,000× the energy of this one
  3. Around the size people start to feel M 3.0 42× the energy of this one
  4. This earthquake M 1.9 about 23 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 51,000 times the energy of this one.

Before 2016, the USGS record lists 24 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 28 km SE of this epicentre
  2. 6.5 Near Morgan Hill, California · 44 km ESE of this epicentre
  3. 6.3 22 km S of Davenport, California · 46 km S of this epicentre
  4. 6.3 16 km SW of Davenport, California · 38 km SSW of this epicentre
  5. 6.2 Near San Jose, California · 29 km ENE 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 37.2110, -122.1137. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Cruz County, CA 24 km (15 mi) SSE earthquakes near Santa Cruz County
San Mateo County, CA 32 km (20 mi) NW earthquakes near San Mateo County
Santa Clara County, CA 38 km (23 mi) E earthquakes near Santa Clara County
Alameda County, CA 52 km (32 mi) NNE earthquakes near Alameda County
Contra Costa County, CA 80 km (50 mi) N earthquakes near Contra Costa County
San Francisco County, CA 99 km (62 mi) NW earthquakes near San Francisco County

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

Aftershocks so far

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

  1. 3.0 5 km ESE of Interlaken, CA
  2. 2.0 12 km SE of Sunol, CA
  3. 2.0 2 km ENE of Hayward, CA
  4. 2.1 15 km N of Morgan Hill, CA
  5. 1.5 7 km WSW of Gilroy, CA
  6. 1.6 5 km ESE of Interlaken, CA
  7. 1.5 9 km ENE of Morgan Hill, CA
  8. 1.9 10 km E of Alum Rock, CA
  9. 1.5 16 km N of Morgan Hill, CA
  10. 1.5 7 km ESE of Fremont, CA
  11. 1.9 7 km SSE of Portola Valley, CA
  12. 2.4 12 km WNW of Bonny Doon, CA
  13. 2.3 16 km N of Morgan Hill, CA
  14. 2.1 4 km ESE of Union City, CA
  15. 1.8 6 km E of Fremont, 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.