Earthquake near Boulder Creek, 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 53 km (33 mi) from the epicentre. In Boulder Creek, 10 km away, the estimate is intensity III (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 10 km, intensity III · Saratoga 14 km, intensity III · Loyola 17 km, intensity III · Los Gatos 17 km, intensity III · Cupertino 17 km, intensity III · Los Altos 20 km, intensity II · Portola Valley 21 km, intensity II · Campbell 21 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 110,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 4,700× the energy of this one
3. Magna, Utah 2020 M 5.7 3,300× the energy of this one
4. This earthquake M 3.4 about 1.6 tons of TNT
5. Around the size people start to feel M 3.0 this one released 3.3× more

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 20 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 The 1989 Loma Prieta, California Earthquake · 32 km SE of this epicentre Oct 18, 1989
2. 6.5 Near Morgan Hill, California · 48 km ESE of this epicentre Jul 1, 1911
3. 6.3 22 km S of Davenport, California · 45 km S of this epicentre Oct 22, 1926
4. 6.3 16 km SW of Davenport, California · 35 km SSW of this epicentre Oct 22, 1926
5. 6.2 Near San Jose, California · 34 km ENE of this epicentre Aug 3, 1903

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 37.2077, -122.1655. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 1.5 2 km S of Loyola, California 18:23 UTC
2. 1.8 11 km ESE of East Foothills, California 19:57 UTC
3. 1.5 11 km ESE of East Foothills, California 19:51 UTC
4. 3.3 11 km ESE of East Foothills, California 15:26 UTC
5. 1.9 0 km WNW of Loyola, California 00:04 UTC
6. 2.1 11 km ESE of East Foothills, California 16:45 UTC
7. 1.5 2 km S of Loyola, California 18:11 UTC
8. 1.6 3 km S of Loyola, California 17:34 UTC
9. 2.1 4 km WSW of Saratoga, California 11:28 UTC
10. 1.8 14 km E of Seven Trees, California 09:16 UTC
11. 2.2 5 km ENE of East Foothills, California 10:59 UTC
12. 1.8 3 km SE of Hayward, California 23:58 UTC
13. 2.1 6 km NE of East Foothills, California 14:10 UTC
14. 2.1 8 km SSE of Sunol, California 05:19 UTC
15. 1.6 2 km WNW of Los Altos Hills, California 20:30 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 09:23 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.