Earthquake near Bonny Doon, CA

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 36 km (22 mi) from the epicentre. In Bonny Doon, 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.

Likely felt in: Boulder Creek 24 km, intensity II · Scotts Valley 33 km, intensity II · Santa Cruz 34 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 990 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 340,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 15,000× the energy of this one
3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
4. This earthquake M 3.0 about 990 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 13 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 The 1989 Loma Prieta, California Earthquake · 45 km E of this epicentre Oct 18, 1989
2. 6.3 22 km S of Davenport, California · 34 km SSE of this epicentre Oct 22, 1926
3. 6.3 16 km SW of Davenport, California · 17 km SSE of this epicentre Oct 22, 1926
4. 5.8 7 km NNW of Boulder Creek, California · 25 km ENE of this epicentre Sep 5, 1955
5. 5.7 Monterey Bay area, California · 40 km SE of this epicentre Dec 31, 1910

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 37.0745, -122.3892. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 1.6 6km SSE of Portola Valley, CA 18:08 UTC
2. 2.5 6km SSE of Portola Valley, CA 11:08 UTC
3. 2.2 34km W of Bonny Doon, CA 10:03 UTC
4. 2.0 4km SSE of Highlands-Baywood Park, CA 14:24 UTC
5. 1.9 11km SW of Bonny Doon, CA 06:03 UTC
6. 1.7 22km W of Bonny Doon, CA 09:07 UTC
7. 2.7 5km SSW of Lexington Hills, CA 16:51 UTC
8. 1.6 3km SSW of Half Moon Bay, CA 10:02 UTC
9. 2.2 3km SSW of Half Moon Bay, CA 21:48 UTC
10. 1.6 3km SSW of Half Moon Bay, CA 10:24 UTC
11. 1.7 4km S of Portola Valley, CA 03:22 UTC
12. 1.7 4km S of Portola Valley, CA 02:32 UTC
13. 1.7 23km WNW of Bonny Doon, CA 00:17 UTC
14. 1.6 3km W of Fruitdale, CA 12:10 UTC
15. 1.5 11km WSW of Saratoga, CA 19:35 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:23 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.