QuakeIndex

Fault · California

Sargent fault

54 kmlong (34 mi), as mapped
1–5 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
149quakes of M2.5+ within 10 km since 2016

In plain English

The two sides move 1 to 5 mm a year — 10 to 50 cm (4 to 20 inches) every century.

It has broken the ground surface within the last 150 years.

The largest earthquake recorded near it was M 6.5 in 1840 (Near San Juan Bautista, California) — about 180,000 times the energy of an M3.0, the size people start to feel. It released about 85 kilotons of TNT.

USGS maps it as 2 sections: northwestern section, southeastern section.

This week vs. its last ten years

0/100

quiet

0 quakes of M1.5+ within 5 km of the trace in the last 7 days — busier than 0% of weeks since 2016. A normal week: 0–1.

Computed from the USGS catalogue · a description of the past, not a forecast · method

San Andreas faultGreat Valley thrust fault systemSan Gregorio faultCalaveras faultHayward faultGreenville faultMonterey Bay- Tularcitos faultZayante-Vergeles faultOrtigalita faultMonte Vista-Shannon faultButano faultEast Monterey Bay faultQuien Sabe faultPleasanton faultSerra faultTres Pinos faultCorral Hollow-Carnegie faultLas Positas fault M 6.5 · 1840 · Near San Juan Bautista, California M 6.5 · 1865 · South of San Jose, California M 6.5 · 1911 · Near Morgan Hill, California M 6.4 · 1836 · Near San Juan Bautista, California M 6.3 · 1890 · East of Watsonville, California M 6.3 · 1897 · Near Gilroy, California
The Sargent fault as mapped at the surface (glowing), with the other mapped faults nearby, 149 of the M2.5+ earthquakes within 10 km of it since 2016 (dots), and the epicentres of the large historic earthquakes recorded near it (rings). Traces: USGS Quaternary Fault and Fold Database. Historic epicentres are estimates.

Every year since 2016

Earthquakes of M2.5+ with an epicentre within 10 km of the mapped trace. Near is not the same as on: some will have slipped on neighbouring faults.

The big ones recorded near it

  1. M 6.5 Near San Juan Bautista, California
    January 18, 1840 · epicentre 8 km from the trace
  2. M 6.5 South of San Jose, California
    October 8, 1865 · epicentre 8 km from the trace
  3. M 6.5 Near Morgan Hill, California
    July 1, 1911 · epicentre 11 km from the trace
  4. M 6.4 Near San Juan Bautista, California
    June 10, 1836 · epicentre 3 km from the trace
  5. M 6.3 East of Watsonville, California
    April 24, 1890 · epicentre 4 km from the trace
  6. M 6.3 Near Gilroy, California
    June 20, 1897 · epicentre 10 km from the trace
  7. M 4.2 4km SE of Aromas, CA
    January 17, 2021 · epicentre 8 km from the trace
  8. M 4.2 3 km of Aromas, CA
    September 29, 2024 · epicentre 6 km from the trace

Before 1973 from the USGS ComCat historical catalogue (within 25 km; epicentres of old earthquakes are estimates). Since 2016, M4+ within 10 km.

Most recent near it

  1. M 2.6 2 km ENE of Aromas, CA
    2026-09-17 · 5 km from the trace
  2. M 2.9 11 km ESE of Gilroy, CA
    2026-07-31 · 9 km from the trace
  3. M 2.8 10 km ESE of Gilroy, CA
    2026-07-30 · 9 km from the trace
  4. M 3.0 12 km ESE of Gilroy, CA
    2026-07-27 · 9 km from the trace
  5. M 3.0 5 km ESE of Interlaken, CA
    2026-07-17 · 7 km from the trace
  6. M 2.7 11 km ESE of Gilroy, CA
    2026-07-14 · 9 km from the trace

Neighbouring faults

Fault trace, slip rate and age: USGS Quaternary Fault and Fold Database (public domain), simplified for the web. Earthquakes: USGS ComCat. QuakeIndex does not forecast earthquakes; a fault's history describes the past. For early warning use ShakeAlert.