QuakeIndex

Earthquake · reviewed by a seismologist

M 1.7md

Earthquake near South Dos Palos, CA

No earthquake was likely felt in South Dos Palos in the 24 hours to 2:35 pm PST (22:35 UTC). The last one was M 3.9, 64 km (40 mi) SW, at 3:19 am PDT on 11 August 2026, estimated intensity II (weak) in town; 34 felt reports to USGS. Every earthquake near South Dos Palos

This page: a magnitude 1.7 earthquake was recorded 27 km (17 mi) south-southwest of South Dos Palos, CA, at 9:47 am PST on 28 December 2021 (17:47 UTC), 1.9 km deep.

USGS: 28km SSW of South Dos Palos, CA

9:47 am PST, Dec 28, 2021 · · 1.9 km deep · released about 9.6 lb of TNT

10 km30 km60 km120 km N San Benito County 29 kmMerced County 50 kmMonterey County 73 kmStanislaus County 91 kmSanta Clara County 93 kmFresno County 104 kmMadera County 108 kmSanta Cruz County 110 kmKings County 118 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
9:47 am PST on 28 December 2021 ()
Where
27 km (17 mi) south-southwest of South Dos Palos, CA · earthquakes near South Dos Palos
Magnitude
M 1.7 (md)
Depth
1.9 km below the surface
Felt
no reports yet
Nearest
San Benito County, 29 km SW
Nearest mapped fault
Great Valley thrust fault system, 6 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 1780 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 South Dos Palos, 27 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.

How big was it?

This earthquake released about 9.6 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 1,600,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 1,100,000× the energy of this one
  3. Around the size people start to feel M 3.0 99× the energy of this one
  4. This earthquake M 1.7 about 9.6 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 36,000 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.1 Northwest of Huron, California · 34 km SE of this epicentre
  2. 5.9 10 km SE of Tres Pinos, California · 36 km W of this epicentre
  3. 5.8 Near Paicines, California · 40 km WSW of this epicentre
  4. 5.5 12 km S of Tres Pinos, California · 44 km W of this epicentre
  5. 5.5 3 km ENE of Tres Pinos, California · 42 km W 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 36.7555, -120.8182. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
San Benito County, CA 29 km (18 mi) SW earthquakes near San Benito County
Merced County, CA 50 km (31 mi) N earthquakes near Merced County
Monterey County, CA 73 km (45 mi) SW earthquakes near Monterey County
Stanislaus County, CA 91 km (57 mi) N earthquakes near Stanislaus County
Santa Clara County, CA 93 km (58 mi) NW earthquakes near Santa Clara County
Fresno County, CA 104 km (64 mi) E earthquakes near Fresno County

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

Aftershocks so far

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

  1. 2.5 12km N of New Idria, CA
  2. 1.7 11km NE of Pinnacles, CA
  3. 1.8 11km NE of Pinnacles, CA
  4. 2.0 3km E of Pinnacles, CA
  5. 1.5 4km ENE of Pinnacles, CA
  6. 1.7 3km NNW of Pinnacles, CA
  7. 2.2 7km NNW of Pinnacles, CA
  8. 1.7 16km SSE of Tres Pinos, CA
  9. 1.8 16km ENE of Pinnacles, CA
  10. 1.7 10km SE of Pinnacles, CA
  11. 1.6 23km WSW of New Idria, CA
  12. 2.0 14km S of Tres Pinos, CA
  13. 2.3 9km SSW of Tres Pinos, CA
  14. 2.0 22km SE of Pinnacles, CA
  15. 1.5 3km N of Pinnacles, 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.