QuakeIndex

quarry blast · reviewed by a seismologist

M 1.5md

Earthquake near Gilroy, CA

Yes: an earthquake was likely felt in Gilroy in the last 24 hours. M 1.6, 9 km (5 mi) E of Gilroy, at 1:22 am PST on 12 November 2026 (09:22 UTC); the estimated shaking in Gilroy was intensity II (weak). Every earthquake near Gilroy

No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.5 quarry blast was recorded 9 km (5 mi) northeast of Gilroy, CA, at 11:07 am PDT on 17 May 2021 (18:07 UTC), less than 1 km deep.

USGS: 9km NE of Gilroy, CA

10 km (6 mi) NE of Gilroy, CA · 37 km (23 mi) SE of San Jose, CA

11:07 am PDT, May 17, 2021 · · -0.3 km deep · released about 6.2 lb of TNT

10 km30 km60 km120 km N Santa Clara County 23 kmSanta Cruz County 45 kmSan Benito County 63 kmStanislaus County 71 kmMerced County 71 kmAlameda County 74 kmSan Mateo County 85 kmMonterey County 94 kmSan Joaquin County 99 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
11:07 am PDT on 17 May 2021 ()
Where
9 km (5 mi) northeast of Gilroy, CA · earthquakes near Gilroy
Magnitude
M 1.5 (md)
Depth
-0.3 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 23 km NW
Nearest mapped fault
Calaveras fault, 1 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 2001 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 10 km (6 mi) from the epicentre. In Gilroy, 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: Gilroy 9 km, intensity II. Estimated for each town centre; each link is that town's own record.

USGS catalogues this as quarry blast, not an earthquake.

How big was it?

This earthquake released about 6.2 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
  3. Around the size people start to feel M 3.0 150× the energy of this one
  4. This earthquake M 1.5 about 6.2 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 2016-07-19 — about 10,000 times the energy of this one.

Before 2016, the USGS record lists 31 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 33 km W of this epicentre
  2. 6.5 Near Morgan Hill, California · 12 km WNW of this epicentre
  3. 6.2 Near San Jose, California · 36 km NW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 31 km NNW of this epicentre
  5. 6.1 Near San Jose, California · 30 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 37.0683, -121.5093. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 23 km (15 mi) NW earthquakes near Santa Clara County
Santa Cruz County, CA 45 km (28 mi) W earthquakes near Santa Cruz County
San Benito County, CA 63 km (39 mi) SE earthquakes near San Benito County
Stanislaus County, CA 71 km (44 mi) NE earthquakes near Stanislaus County
Merced County, CA 71 km (44 mi) ENE earthquakes near Merced County
Alameda County, CA 74 km (46 mi) NNW earthquakes near Alameda County

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

Aftershocks so far

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

  1. 1.9 12km S of Tres Pinos, CA
  2. 1.6 9km SSW of Tres Pinos, CA
  3. 1.8 2km ENE of Aromas, CA
  4. 1.6 7km ESE of Prunedale, CA
  5. 2.2 4km NNW of Hollister, CA
  6. 1.8 7km S of Tres Pinos, CA
  7. 2.7 4km NNW of Hollister, CA
  8. 1.7 9km NNE of Alum Rock, CA
  9. 1.8 12km SSW of Tres Pinos, CA
  10. 1.9 3km SSW of San Juan Bautista, CA
  11. 1.6 8km NE of Ridgemark, CA
  12. 2.0 3km SSW of San Juan Bautista, CA
  13. 1.5 8km ENE of Gilroy, CA
  14. 2.4 9km NE of San Martin, CA
  15. 1.7 2km ENE of Aromas, 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.