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 23 km (14 mi) from the epicentre. In Boulder Creek, 7 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 7 km, intensity III · Saratoga 12 km, intensity II · Los Gatos 14 km, intensity II · Cupertino 17 km, intensity II · Scotts Valley 18 km, intensity II · Campbell 19 km, intensity II · Sunnyvale 22 km, intensity II · Los Altos 22 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 360 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.7 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 42,000× the energy of this one
2. Magna, Utah 2020 M 5.7 30,000× the energy of this one
3. Around the size people start to feel M 3.0 2.6× the energy of this one
4. This earthquake M 2.7 about 360 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 4.1 on 2017-10-10 — about 110 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 · 27 km SE of this epicentre Oct 18, 1989
2. 6.5 Near Morgan Hill, California · 44 km E of this epicentre Jul 1, 1911
3. 6.3 22 km S of Davenport, California · 43 km S of this epicentre Oct 22, 1926
4. 6.3 16 km SW of Davenport, California · 35 km SW of this epicentre Oct 22, 1926
5. 6.2 Near San Jose, California · 31 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 37.1867, -122.1197. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 1.8 15km NNE of Morgan Hill, CA 19:20 UTC
2. 1.7 3km S of Los Altos Hills, CA 06:16 UTC
3. 1.6 3km ESE of Union City, CA 11:42 UTC
4. 1.7 16km E of Seven Trees, CA 11:13 UTC
5. 1.9 16km E of Seven Trees, CA 07:51 UTC
6. 3.0 8km NE of Alum Rock, CA 11:44 UTC
7. 1.8 9km ENE of Milpitas, CA 01:24 UTC
8. 2.1 9km ENE of Milpitas, CA 13:44 UTC
9. 2.1 2km SSW of Los Altos Hills, CA 16:48 UTC
10. 2.8 3km S of Los Altos Hills, CA 04:26 UTC
11. 1.8 2km S of Los Altos Hills, CA 19:21 UTC
12. 2.6 16km E of Seven Trees, CA 10:57 UTC
13. 1.5 8km ENE of Alum Rock, CA 12:24 UTC
14. 1.6 9km NE of Milpitas, CA 01:12 UTC
15. 1.7 7km N of Day Valley, CA 08:15 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 01:09 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.