Earthquake · reviewed by a seismologist
M 2.3md
Earthquake near Gilroy, CA
No earthquake was likely felt in Gilroy in the 24 hours to 12:03 am PST (08:03 UTC). The last one was M 2.5, 9 km (6 mi) E, at 7:27 pm PST on 1 November 2026, estimated intensity II (weak) in town; 2 felt reports to USGS. Every earthquake near Gilroy
This page: a magnitude 2.3 earthquake was recorded 6 km (4 mi) south-southwest of Gilroy, CA, at 9:28 am PDT on 23 October 2021 (16:28 UTC), 3.8 km deep. 2 people have reported feeling it to USGS.
USGS: 6km SSW of Gilroy, CA
6 km (4 mi) S of Gilroy, CA · 43 km (27 mi) SSE of San Jose, CA
- When
- 9:28 am PDT on 23 October 2021 ()
- Where
- 6 km (4 mi) south-southwest of Gilroy, CA · earthquakes near Gilroy
- Magnitude
- M 2.3 (md)
- Depth
- 3.8 km below the surface
- Felt
- 2 reports · strongest reported intensity II
- Nearest
- Santa Clara County, 31 km NNW
- Nearest mapped fault
- Sargent 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 1835 days ago
Earthquake alerts for Gilroy, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
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 19 km (12 mi) from the epicentre. In Gilroy, 6 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 6 km, intensity II · Watsonville 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 79 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 190,000× the energy of this one
- Magna, Utah 2020 M 5.7 130,000× the energy of this one
- Around the size people start to feel M 3.0 12× the energy of this one
- This earthquake M 2.3 about 79 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 4.7 on 2019-10-15 — about 4,400 times the energy of this one.
Before 2016, the USGS record lists 30 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 27 km WNW of this epicentre
- 6.5 Near Morgan Hill, California · 18 km NNW of this epicentre
- 6.2 Near San Jose, California · 43 km NNW of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 40 km N of this epicentre
- 6.1 Near San Jose, California · 33 km NW 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 36.9552, -121.5913. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Clara County, CA | 31 km (19 mi) | NNW | earthquakes near Santa Clara County |
| Santa Cruz County, CA | 38 km (23 mi) | W | earthquakes near Santa Cruz County |
| San Benito County, CA | 59 km (37 mi) | SE | earthquakes near San Benito County |
| Merced County, CA | 82 km (51 mi) | ENE | earthquakes near Merced County |
| Alameda County, CA | 82 km (51 mi) | NNW | earthquakes near Alameda County |
| Monterey County, CA | 83 km (52 mi) | SSE | earthquakes near Monterey County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
38 earthquakes have been recorded within 50 km since this one.
- 1.7 9km SSW of Tres Pinos, CA
- 2.5 3km ENE of Aromas, CA
- 2.3 10km S of Tres Pinos, CA
- 2.7 9km ENE of Morgan Hill, CA
- 1.6 6km S of Tres Pinos, CA
- 1.6 8km SW of Ridgemark, CA
- 1.7 16km NW of Pinnacles, CA
- 1.9 13km S of Tres Pinos, CA
- 1.6 13km S of Tres Pinos, CA
- 2.0 12km SW of Ridgemark, CA
- 2.1 4km W of San Juan Bautista, CA
- 2.9 12km S of Tres Pinos, CA
- 1.5 11km S of Tres Pinos, CA
- 2.6 12km S of Tres Pinos, CA
- 2.2 11km NW of Morgan Hill, 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
- 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.