QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Gilroy, CA

No earthquake was likely felt in Gilroy in the 24 hours to 10:51 pm PST (06:51 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 1.6 earthquake was recorded 7 km (4 mi) south of Gilroy, CA, at 9:12 am PDT on 28 April 2017 (16:12 UTC), 4.9 km deep.

USGS: 6 km S of Gilroy, California

7 km (5 mi) SSE of Gilroy, CA · 45 km (28 mi) SSE of San Jose, CA

9:12 am PDT, Apr 28, 2017 · · 4.9 km deep · released about 8.4 lb of TNT

10 km30 km60 km120 km N Santa Clara County 33 kmSanta Cruz County 41 kmSan Benito County 56 kmMerced County 79 kmMonterey County 81 kmStanislaus County 84 kmAlameda County 84 kmSan Mateo County 89 kmSan Joaquin County 113 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
9:12 am PDT on 28 April 2017 ()
Where
7 km (4 mi) south of Gilroy, CA · earthquakes near Gilroy
Magnitude
M 1.6 (md)
Depth
4.9 km below the surface
Felt
no reports yet
Nearest
Santa Clara County, 33 km NNW
Nearest mapped fault
Sargent 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 3484 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, 7 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 7 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 8.4 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 1,800,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,300,000× the energy of this one
  3. Around the size people start to feel M 3.0 110× the energy of this one
  4. This earthquake M 1.6 about 8.4 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 7,700 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 · 31 km WNW of this epicentre
  2. 6.5 Near Morgan Hill, California · 20 km NNW of this epicentre
  3. 6.2 Near San Jose, California · 45 km NNW of this epicentre
  4. 6.2 The 1984 Morgan Hill, California Earthquake · 42 km NNW of this epicentre
  5. 6.1 Near San Jose, California · 36 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 36.9442, -121.5540. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Clara County, CA 33 km (21 mi) NNW earthquakes near Santa Clara County
Santa Cruz County, CA 41 km (25 mi) W earthquakes near Santa Cruz County
San Benito County, CA 56 km (35 mi) SE earthquakes near San Benito County
Merced County, CA 79 km (49 mi) ENE earthquakes near Merced County
Monterey County, CA 81 km (50 mi) SSE earthquakes near Monterey County
Stanislaus County, CA 84 km (52 mi) NE earthquakes near Stanislaus 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. 1.5 5 km SSW of Gilroy, California
  2. 2.0 9 km NE of Gilroy, California
  3. 1.9 4 km SE of Tres Pinos, California
  4. 1.8 17 km SSE of Tres Pinos, California
  5. 1.6 9 km SSW of Tres Pinos, California
  6. 1.6 6 km SSE of Gilroy, California
  7. 1.6 1 km SE of Lexington Hills, California
  8. 2.0 5 km SE of Tres Pinos, California
  9. 2.5 11 km S of Tres Pinos, California
  10. 2.8 11 km S of Tres Pinos, California
  11. 2.1 9 km SSW of Tres Pinos, California
  12. 2.9 11 km S of Tres Pinos, California
  13. 2.7 6 km NE of Ridgemark, California
  14. 1.7 19 km ESE of East Foothills, California
  15. 2.7 4 km NNW of Hollister, California

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.