QuakeIndex

Earthquake · reviewed by a seismologist

M 2.4md

Earthquake near San Martin, CA

No earthquake was likely felt in San Martin in the 24 hours to 1:34 am PST (09:34 UTC). The last one was M 2.5, 17 km (10 mi) SE, at 7:27 pm PST on 1 November 2026, estimated intensity II (weak) in town; 2 felt reports to USGS. Every earthquake near San Martin

This page: a magnitude 2.4 earthquake was recorded 9 km (6 mi) northeast of San Martin, CA, at 11:36 am PDT on 29 June 2021 (18:36 UTC), 5.5 km deep. 1 person has reported feeling it to USGS.

USGS: 9km NE of San Martin, CA

15 km (9 mi) NNE of Gilroy, CA · 31 km (20 mi) SE of San Jose, CA

11:36 am PDT, Jun 29, 2021 · · 5.5 km deep · released about 120 lb of TNT

10 km30 km60 km120 km N Santa Clara County 18 kmSanta Cruz County 45 kmStanislaus County 67 kmAlameda County 67 kmSan Benito County 70 kmMerced County 72 kmSan Mateo County 81 kmSan Joaquin County 92 kmContra Costa County 95 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
11:36 am PDT on 29 June 2021 ()
Where
9 km (6 mi) northeast of San Martin, CA · earthquakes near San Martin
Magnitude
M 2.4 (md)
Depth
5.5 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Santa Clara County, 18 km NW
Nearest mapped fault
Calaveras fault, 2 km from its surface trace — near is not the same as on
Status
Reviewed by a seismologist

USGS · last changed by USGS · we first saw it 1960 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 20 km (12 mi) from the epicentre. In San Martin, 9 km away, the estimate is intensity II (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 11 km, intensity II · Gilroy 14 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 92,000× the energy of this one
  3. Around the size people start to feel M 3.0 8.2× the energy of this one
  4. This earthquake M 2.4 about 120 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 520 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
  2. 6.5 Near Morgan Hill, California · 10 km WSW of this epicentre
  3. 6.2 Near San Jose, California · 31 km NW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 24 km NW of this epicentre
  5. 6.1 Near San Jose, California · 25 km WNW of this epicentre

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 37.1300, -121.5268. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 18 km (11 mi) NW earthquakes near Santa Clara County
Santa Cruz County, CA 45 km (28 mi) WSW earthquakes near Santa Cruz County
Stanislaus County, CA 67 km (41 mi) NE earthquakes near Stanislaus County
Alameda County, CA 67 km (42 mi) NNW earthquakes near Alameda County
San Benito County, CA 70 km (43 mi) SE earthquakes near San Benito County
Merced County, CA 72 km (44 mi) E earthquakes near Merced County

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

Aftershocks so far

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

  1. 1.9 10km NE of Milpitas, CA
  2. 1.5 6km SW of Gilroy, CA
  3. 2.2 6km SW of Gilroy, CA
  4. 2.0 14km N of Morgan Hill, CA
  5. 2.4 11km NE of Milpitas, CA
  6. 1.6 2km E of Aromas, CA
  7. 1.9 15km E of Seven Trees, CA
  8. 1.7 3km ESE of Aromas, CA
  9. 1.7 18km SSW of Gustine, CA
  10. 1.8 15km E of Seven Trees, CA
  11. 1.8 15km E of Seven Trees, CA
  12. 2.1 15km E of Seven Trees, CA
  13. 1.7 3km E of Aromas, CA
  14. 3.1 5km S of Ridgemark, CA
  15. 2.9 9km SW of Tres Pinos, CA

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

On USGS

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.