Earthquake near Morgan Hill, 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 Morgan Hill, 9 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: Morgan Hill 9 km, intensity III · Gilroy 21 km, intensity III · San Jose 32 km, intensity II · Campbell 34 km, intensity II · Watsonville 35 km, intensity II · Los Gatos 35 km, intensity II · Santa Clara 38 km, intensity II · Milpitas 39 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 1.5 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 5,100× the energy of this one
3. Magna, Utah 2020 M 5.7 3,600× the energy of this one
4. This earthquake M 3.3 about 1.5 tons of TNT
5. Around the size people start to feel M 3.0 this one released 3.1× 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

The largest earthquake within 50 km since 2016 was M 4.2 on 2021-01-17 — about 20 times the energy of this one.

Before 2016, the USGS record lists 27 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 The 1989 Loma Prieta, California Earthquake · 32 km WSW of this epicentre Oct 18, 1989
2. 6.5 Near Morgan Hill, California · 10 km SSW of this epicentre Jul 1, 1911
3. 6.2 Near San Jose, California · 23 km WNW of this epicentre Aug 3, 1903
4. 6.2 The 1984 Morgan Hill, California Earthquake · 16 km NNW of this epicentre Apr 24, 1984
5. 6.1 Near San Jose, California · 19 km W of this epicentre Jun 11, 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 37.1923, -121.5807. 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. 2.2 6km S of San Juan Bautista, CA 23:15 UTC
2. 1.6 15km E of Seven Trees, CA 09:08 UTC
3. 2.2 2km W of Tres Pinos, CA 06:24 UTC
4. 2.5 3km WSW of San Juan Bautista, CA 12:48 UTC
5. 1.9 3km WSW of Cupertino, CA 08:39 UTC
6. 1.7 2km ENE of Aromas, CA 18:18 UTC
7. 1.6 6km SW of Ridgemark, CA 06:34 UTC
8. 1.7 28km ENE of Alum Rock, CA 01:35 UTC
9. 1.8 9km ENE of Morgan Hill, CA 18:27 UTC
10. 3.4 14km ESE of Alum Rock, CA 22:55 UTC
11. 1.5 4km S of Sunol, CA 19:25 UTC
12. 2.8 10km NE of San Martin, CA 00:52 UTC
13. 1.5 7km NE of San Martin, CA 02:15 UTC
14. 1.7 2km ENE of Aromas, CA 18:02 UTC
15. 2.9 5km N of Hollister, CA 16:39 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:21 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.