Earthquake near San Martin, 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 26 km (16 mi) from the epicentre. In San Martin, 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: Morgan Hill 10 km, intensity III · Gilroy 16 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 460 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 33,000× the energy of this one
2. Magna, Utah 2020 M 5.7 23,000× the energy of this one
3. Around the size people start to feel M 3.0 2.1× the energy of this one
4. This earthquake M 2.8 about 460 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 4.2 on 2021-01-17 — about 130 times the energy of this one.

Before 2016, the USGS record lists 28 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 The 1989 Loma Prieta, California Earthquake · 33 km WSW of this epicentre Oct 18, 1989
2. 6.5 Near Morgan Hill, California · 10 km WSW of this epicentre Jul 1, 1911
3. 6.2 Near San Jose, California · 28 km NW of this epicentre Aug 3, 1903
4. 6.2 The 1984 Morgan Hill, California Earthquake · 22 km NW of this epicentre Apr 24, 1984
5. 6.1 Near San Jose, California · 24 km WNW 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 37.1508, -121.5392. 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. 2.9 15km E of Seven Trees, CA 18:47 UTC
2. 5.1 15km ESE of Alum Rock, CA 18:42 UTC
3. 1.6 9km SW of Ridgemark, CA 20:31 UTC
4. 1.6 9km ENE of San Martin, CA 16:22 UTC
5. 2.6 9km ENE of San Martin, CA 15:14 UTC
6. 1.8 6km SW of Gilroy, CA 17:57 UTC
7. 2.4 4km ESE of Tres Pinos, CA 00:55 UTC
8. 2.5 10km E of Alum Rock, CA 20:02 UTC
9. 1.7 2km E of Aromas, CA 18:11 UTC
10. 1.6 3km SSW of Monte Sereno, CA 17:54 UTC
11. 2.2 15km N of Morgan Hill, CA 04:05 UTC
12. 1.5 10km NNE of Milpitas, CA 23:40 UTC
13. 1.7 4km SE of Tres Pinos, CA 15:15 UTC
14. 2.1 10km SSW of Ridgemark, CA 19:28 UTC
15. 1.8 9km NNE of Alum Rock, CA 01:05 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 04:13 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.