Earthquake near Ridgemark, 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 35 km (22 mi) from the epicentre. In Ridgemark, 11 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: Hollister 12 km, intensity III · Prunedale 19 km, intensity II · Salinas 19 km, intensity II · Gilroy 30 km, intensity II · Watsonville 31 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 890 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 6.7 380,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 17,000× the energy of this one
3. Magna, Utah 2020 M 5.7 12,000× the energy of this one
4. This earthquake M 3.0 about 890 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 4.6 on 2017-11-13 — about 250 times the energy of this one.

Before 2016, the USGS record lists 25 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 The 1989 Loma Prieta, California Earthquake · 49 km NW of this epicentre Oct 18, 1989
2. 6.5 Near Morgan Hill, California · 43 km NNW of this epicentre Jul 1, 1911
3. 5.9 10 km SE of Tres Pinos, California · 21 km E of this epicentre Apr 9, 1961
4. 5.8 Near Watsonville, California · 30 km NW of this epicentre Mar 11, 1910
5. 5.8 Near Paicines, California · 21 km ESE of this epicentre Aug 6, 1916

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 36.7540, -121.4617. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 1.9 5km SSE of Tres Pinos, CA 04:49 UTC
2. 1.6 10km S of Tres Pinos, CA 21:33 UTC
3. 1.5 13km NNW of Pinnacles, CA 08:54 UTC
4. 1.6 8km SSE of San Juan Bautista, CA 07:31 UTC
5. 2.0 15km S of Tres Pinos, CA 06:52 UTC
6. 2.0 16km SSE of Tres Pinos, CA 09:27 UTC
7. 2.1 12km NW of Pinnacles, CA 01:15 UTC
8. 2.0 3km ESE of Aromas, CA 19:42 UTC
9. 3.0 2km ESE of Aromas, CA 19:41 UTC
10. 2.2 6km NNW of Pinnacles, CA 10:50 UTC
11. 1.8 9km ENE of San Martin, CA 09:15 UTC
12. 2.0 9km ENE of San Martin, CA 09:09 UTC
13. 1.8 12km SE of Pinnacles, CA 08:48 UTC
14. 2.6 11km SE of Pinnacles, CA 07:46 UTC
15. 2.0 16km SSE of Tres Pinos, CA 05:24 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:42 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.