QuakeIndex

Earthquake · reviewed by a seismologist

M 2.0md

Earthquake near Tracy, CA

No earthquake was likely felt in Tracy in the 24 hours to 5:44 pm PST (01:44 UTC). The last one was M 3.5, 36 km (22 mi) S, at 7:21 am PDT on 27 September 2026, estimated intensity II (weak) in town; 8 felt reports to USGS. Every earthquake near Tracy

This page: a magnitude 2.0 earthquake was recorded 18 km (11 mi) south-southeast of Tracy, CA, at 9:08 pm PDT on 22 July 2023 (04:08 UTC), 5.6 km deep.

USGS: 13 km WNW of Westley, CA

54 km (34 mi) NE of San Jose, CA · 18 km (11 mi) SE of Tracy, CA

9:08 pm PDT, Jul 22, 2023 · · 5.6 km deep · released about 31 lb of TNT

Every earthquake near Tracy Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Stanislaus County 29 kmSan Joaquin County 38 kmAlameda County 51 kmSanta Clara County 52 kmContra Costa County 65 kmMerced County 70 kmSanta Cruz County 88 kmSolano County 92 kmSan Mateo County 94 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
9:08 pm PDT on 22 July 2023 ()
Where
18 km (11 mi) south-southeast of Tracy, CA · earthquakes near Tracy
Magnitude
M 2.0 (md)
Depth
5.6 km below the surface
Felt
no reports yet
Nearest
Stanislaus County, 29 km E
Nearest mapped fault
Great Valley thrust fault system, 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 1205 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 15 km (9 mi) from the epicentre. In Tracy, 18 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: Patterson, Ripon, Riverdale Park, Manteca, Salida, Lathrop.

How big was it?

This earthquake released about 31 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 480,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 340,000× the energy of this one
  3. Around the size people start to feel M 3.0 31× the energy of this one
  4. This earthquake M 2.0 about 31 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 5.1 on 2022-10-25 — about 38,000 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 The 1984 Morgan Hill, California Earthquake · 44 km SW of this epicentre
  2. 5.8 The 1980 Livermore, California Earthquake · 47 km NW of this epicentre
  3. 5.7 15 km NE of East Foothills, California · 34 km WSW of this epicentre
  4. 5.5 6 km NNE of East Foothills, California · 43 km WSW of this epicentre
  5. 5.4 9 km NE of Livermore, California · 37 km WNW 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 37.5938, -121.3325. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Stanislaus County, CA 29 km (18 mi) E earthquakes near Stanislaus County
San Joaquin County, CA 38 km (24 mi) N earthquakes near San Joaquin County
Alameda County, CA 51 km (32 mi) W earthquakes near Alameda County
Santa Clara County, CA 52 km (32 mi) SW earthquakes near Santa Clara County
Contra Costa County, CA 65 km (41 mi) NW earthquakes near Contra Costa County
Merced County, CA 70 km (43 mi) SE earthquakes near Merced 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. 2.1 11 km W of Patterson, CA
  2. 1.6 11 km WSW of Patterson, CA
  3. 1.5 16 km SW of Westley, CA
  4. 1.7 11 km W of Patterson, CA
  5. 2.0 11 km WSW of Patterson, CA
  6. 1.9 11 km SSW of Westley, CA
  7. 1.6 18 km WSW of Patterson, CA
  8. 1.6 11 km W of Patterson, CA
  9. 3.0 10 km WSW of Patterson, CA
  10. 1.5 17 km WSW of Patterson, CA
  11. 1.5 18 km WSW of Patterson, CA
  12. 1.5 18 km SW of Westley, CA
  13. 2.0 17 km WSW of Patterson, CA
  14. 2.0 14 km WSW of Patterson, CA
  15. 3.1 16 km WSW of Patterson, 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.