Earthquake near Boulder Creek, CA

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 2 km (1 mi) from the epicentre. In Boulder Creek, 21 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: Bonny Doon, Brookdale, Ben Lomond, Portola Valley, Lompico, Felton.

How big was it?

This earthquake released about 15 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 1,000,000× the energy of this one
2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
3. Around the size people start to feel M 3.0 63× the energy of this one
4. This earthquake M 1.8 about 15 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 14 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 The 1989 Loma Prieta, California Earthquake · 44 km ESE of this epicentre Oct 18, 1989
2. 6.3 22 km S of Davenport, California · 41 km SSE of this epicentre Oct 22, 1926
3. 6.3 16 km SW of Davenport, California · 26 km S of this epicentre Oct 22, 1926
4. 6.1 Near San Jose, California · 50 km E of this epicentre Jun 11, 1903
5. 5.8 7 km NNW of Boulder Creek, California · 19 km E of this epicentre Sep 5, 1955

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 37.1573, -122.3570. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 2.0 3km W of Portola Valley, CA 20:32 UTC
2. 1.5 3km W of Portola Valley, CA 08:08 UTC
3. 1.6 3km W of Portola Valley, CA 19:06 UTC
4. 1.9 3km W of Portola Valley, CA 17:14 UTC
5. 2.7 3km W of Portola Valley, CA 03:09 UTC
6. 1.7 3km W of Portola Valley, CA 00:00 UTC
7. 1.5 9km N of Boulder Creek, CA 16:48 UTC
8. 1.7 3km W of Portola Valley, CA 06:27 UTC
9. 1.8 3km W of Portola Valley, CA 07:11 UTC
10. 1.8 2km SW of Los Altos Hills, CA 02:12 UTC
11. 2.2 5km SSE of Newark, CA 04:03 UTC
12. 1.8 12km WNW of Boulder Creek, CA 08:23 UTC
13. 1.7 3km SW of Lexington Hills, CA 17:20 UTC
14. 1.9 14km SW of Santa Cruz, CA 02:48 UTC
15. 1.8 30km SW of Bonny Doon, CA 17:40 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:43 UTC. 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.