QuakeIndex

Fault · California

Ortigalita fault

71 kmlong (44 mi), as mapped
1–5 mm/yrhow fast it slips
< 15,000 yearssince it last broke the surface
22quakes 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.

Its most recent surface rupture is younger than 15,000 years.

The largest earthquake recorded near it was M 6.3 in 1881 (Southwest of Modesto, California) — about 89,000 times the energy of an M3.0, the size people start to feel. It released about 43 kilotons of TNT.

USGS maps it as 4 sections: Cottonwood Arm section, Little Panoche Valley section, Los Banos Valley section, Piedra Azul 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: 0–0.

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 faultSargent faultMonte Vista-Shannon faultButano faultEast Monterey Bay faultQuien Sabe faultTres Pinos faultCorral Hollow-Carnegie faultLas Positas fault M 6.3 · 1881 · Southwest of Modesto, California
The Ortigalita fault as mapped at the surface (glowing), with the other mapped faults nearby, 22 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 6.3 Southwest of Modesto, California
    April 10, 1881 · epicentre 9 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 2.5 20 km SW of Gustine, CA
    2026-03-16 · 2 km from the trace
  2. M 2.8 22 km SW of South Dos Palos, CA
    2026-03-07 · 9 km from the trace
  3. M 2.7 23 km SW of South Dos Palos, CA
    2026-02-22 · 8 km from the trace
  4. M 2.5 20 km WSW of Gustine, CA
    2025-07-17 · 0 km from the trace
  5. M 3.3 25 km W of Los Banos, CA
    2025-07-01 · 1 km from the trace
  6. M 2.6 29 km SSW of Los Banos, CA
    2025-02-11 · 0 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.