QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Gilroy, CA

No earthquake was likely felt in Gilroy in the 24 hours to 11:36 pm PST (07:36 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 1.7 earthquake was recorded 6 km (4 mi) southwest of Gilroy, CA, at 9:58 pm PST on 16 February 2021 (05:58 UTC), 5.7 km deep. 1 person has reported feeling it to USGS.

USGS: 6km SW of Gilroy, CA

5 km (3 mi) SW of Gilroy, CA · 40 km (25 mi) SSE of San Jose, CA

9:58 pm PST, Feb 16, 2021 · · 5.7 km deep · released about 12 lb of TNT

10 km30 km60 km120 km N Santa Clara County 29 kmSanta Cruz County 35 kmSan Benito County 62 kmAlameda County 80 kmSan Mateo County 83 kmMerced County 84 kmMonterey County 85 kmStanislaus County 86 kmContra Costa County 110 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
9:58 pm PST on 16 February 2021 ()
Where
6 km (4 mi) southwest of Gilroy, CA · earthquakes near Gilroy
Magnitude
M 1.7 (md)
Depth
5.7 km below the surface
Felt
1 report · strongest reported intensity II
Nearest
Santa Clara County, 29 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 2092 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 12 km (7 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. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 870,000× the energy of this one
  3. Around the size people start to feel M 3.0 78× the energy of this one
  4. This earthquake M 1.7 about 12 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 29,000 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 · 24 km WNW of this epicentre
  2. 6.5 Near Morgan Hill, California · 16 km N of this epicentre
  3. 6.2 Near San Jose, California · 40 km NNW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 38 km N of this epicentre
  5. 6.1 Near San Jose, California · 30 km NNW 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 36.9677, -121.6203. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 29 km (18 mi) NNW earthquakes near Santa Clara County
Santa Cruz County, CA 35 km (22 mi) W earthquakes near Santa Cruz County
San Benito County, CA 62 km (38 mi) SE earthquakes near San Benito County
Alameda County, CA 80 km (50 mi) NNW earthquakes near Alameda County
San Mateo County, CA 83 km (52 mi) NW earthquakes near San Mateo County
Merced County, CA 84 km (52 mi) ENE earthquakes near Merced County

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

Aftershocks so far

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

  1. 1.7 8km NE of Ridgemark, CA
  2. 1.7 10km E of Gilroy, CA
  3. 1.7 5km WSW of Hollister, CA
  4. 1.8 10km E of Gilroy, CA
  5. 2.1 10km E of Gilroy, CA
  6. 2.0 10km E of Gilroy, CA
  7. 2.3 9km E of Gilroy, CA
  8. 1.7 11km SSW of Tres Pinos, CA
  9. 2.5 15km N of Morgan Hill, CA
  10. 2.0 25km W of Los Banos, CA
  11. 1.7 16km NW of Pinnacles, CA
  12. 1.8 6km S of San Juan Bautista, CA
  13. 1.6 16km N of Morgan Hill, CA
  14. 1.7 3km E of Aromas, CA
  15. 2.3 6km S of San Juan Bautista, 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.