QuakeIndex

Earthquake · reviewed by a seismologist

M 1.6md

Earthquake near Day Valley, CA

No earthquake was likely felt in Day Valley in the 24 hours to 10:19 pm PST (06:19 UTC). The last one was M 1.8, 10 km (6 mi) NNW, at 10:49 pm PDT on 29 October 2026, estimated intensity II (weak) in town. Every earthquake near Day Valley

This page: a magnitude 1.6 earthquake was recorded 6 km (4 mi) north-northwest of Day Valley, CA, at 8:08 pm PST on 7 November 2017 (04:08 UTC), 7.3 km deep.

USGS: 6 km NNW of Day Valley, California

24 km (15 mi) SSW of San Jose, CA · 18 km (11 mi) NE of Santa Cruz, CA

8:08 pm PST, Nov 7, 2017 · · 7.3 km deep · released about 9 lb of TNT

10 km30 km60 km120 km N Santa Cruz County 14 kmSanta Clara County 23 kmSan Mateo County 56 kmAlameda County 62 kmSan Benito County 89 kmContra Costa County 93 kmStanislaus County 94 kmMerced County 104 kmMonterey County 107 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
8:08 pm PST on 7 November 2017 ()
Where
6 km (4 mi) north-northwest of Day Valley, CA · earthquakes near Day Valley
Magnitude
M 1.6 (md)
Depth
7.3 km below the surface
Felt
no reports yet
Nearest
Santa Cruz County, 14 km SW
Nearest mapped fault
San Andreas 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 3281 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 9 km (6 mi) from the epicentre. In Day Valley, 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.

Earthquakes near other towns within 30 km: Lexington Hills, Scotts Valley, Aptos, Soquel, Seacliff, Corralitos.

How big was it?

This earthquake released about 9 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 1,700,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,200,000× 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 9 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 4.1 on 2017-10-10 — about 4,600 times the energy of this one.

Before 2016, the USGS record lists 29 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.9 The 1989 Loma Prieta, California Earthquake · 6 km S of this epicentre
  2. 6.5 Near Morgan Hill, California · 22 km E of this epicentre
  3. 6.3 22 km S of Davenport, California · 42 km SW of this epicentre
  4. 6.3 16 km SW of Davenport, California · 44 km WSW of this epicentre
  5. 6.2 Near San Jose, California · 25 km NNE 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 37.0883, -121.8873. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Santa Cruz County, CA 14 km (8 mi) SW earthquakes near Santa Cruz County
Santa Clara County, CA 23 km (14 mi) NE earthquakes near Santa Clara County
San Mateo County, CA 56 km (35 mi) NW earthquakes near San Mateo County
Alameda County, CA 62 km (39 mi) N earthquakes near Alameda County
San Benito County, CA 89 km (55 mi) SE earthquakes near San Benito County
Contra Costa County, CA 93 km (58 mi) N earthquakes near Contra Costa County

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

Aftershocks so far

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

  1. 2.0 4km WNW of Hollister, CA
  2. 1.6 7km WSW of Gilroy, CA
  3. 1.6 8km SSE of San Juan Bautista, CA
  4. 2.6 4km W of Cupertino, CA
  5. 2.0 3km ESE of Aromas, CA
  6. 3.0 2km ESE of Aromas, CA
  7. 1.8 9km ENE of San Martin, CA
  8. 2.0 9km ENE of San Martin, CA
  9. 1.5 6km SW of Gilroy, CA
  10. 1.6 15km E of Seven Trees, CA
  11. 1.9 10km E of Alum Rock, CA
  12. 3.9 8km ENE of Alum Rock, CA
  13. 3.1 9km ENE of San Martin, CA
  14. 1.8 9km ENE of San Martin, CA
  15. 1.9 9km ENE of San Martin, 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.