QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near Sunnyvale, CA

Yes. A magnitude 1.7 earthquake was recorded 45 km (28 mi) SW of Sunnyvale, CA, at 7:11 am PDT on 31 July 2016 (14:11 UTC), 8.1 km deep.

This was on 31 July 2016. The latest near Sunnyvale: M 2.5 on 19 September 2026.

USGS: 15 km WNW of Davenport, California

55 km (34 mi) WSW of San Jose, CA · 30 km (18 mi) WNW of Santa Cruz, CA

7:11 am PDT, Jul 31, 2016 · · 8.1 km deep · released about 12 lb of TNT

10 km30 km60 km120 km N Santa Cruz County 31 kmSan Mateo County 41 kmSanta Clara County 62 kmAlameda County 77 kmSan Francisco County 96 kmContra Costa County 103 kmMarin County 117 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
7:11 am PDT on 31 July 2016 ()
Where
45 km (28 mi) SW of Sunnyvale, CA · earthquakes near Sunnyvale
Magnitude
M 1.7 (md)
Depth
8.1 km below the surface
Felt
no reports yet
Nearest
Santa Cruz County, 31 km E
Nearest mapped fault
San Gregorio fault, 7 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 3532 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 Sunnyvale, 45 km away, the estimate is intensity I (not felt). 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.

Earthquakes near other towns within 30 km: Bonny Doon, Boulder Creek, Brookdale, Ben Lomond, Felton, Mount Hermon.

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 1,300,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 900,000× the energy of this one
  3. Around the size people start to feel M 3.0 80× 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

No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 42 km E of this epicentre
  2. 6.3 22 km S of Davenport, California · 30 km SSE of this epicentre
  3. 6.3 16 km SW of Davenport, California · 14 km S of this epicentre
  4. 5.8 7 km NNW of Boulder Creek, California · 24 km NE of this epicentre
  5. 5.7 Monterey Bay area, California · 36 km SE 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 37.0503, -122.3557. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Cruz County, CA 31 km (19 mi) E earthquakes near Santa Cruz County
San Mateo County, CA 41 km (25 mi) N earthquakes near San Mateo County
Santa Clara County, CA 62 km (39 mi) ENE earthquakes near Santa Clara County
Alameda County, CA 77 km (48 mi) NNE earthquakes near Alameda County
San Francisco County, CA 96 km (60 mi) NW earthquakes near San Francisco County
Contra Costa County, CA 103 km (64 mi) NNE earthquakes near Contra Costa County

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

Aftershocks so far

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

  1. 1.6 1 km N of Ladera, California
  2. 1.7 2 km S of Loyola, California
  3. 1.5 1 km W of Los Altos Hills, California
  4. 1.5 14 km SW of La Selva Beach, California
  5. 1.6 7 km N of Boulder Creek, California
  6. 1.8 4 km ENE of La Honda, California
  7. 1.7 3 km WSW of Loyola, California
  8. 1.5 2 km S of Loyola, California
  9. 1.6 1 km SE of Lexington Hills, California
  10. 1.5 Northern California
  11. 1.7 3 km S of Loyola, California
  12. 1.6 7 km SSE of Pescadero, California
  13. 2.5 7 km S of Pescadero, California
  14. 1.6 Northern California
  15. 1.6 6 km SW of Loyola, 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.