QuakeIndex

Fault · California

San Gregorio fault

273 kmlong (170 mi), as mapped
> 5 mm/yrhow fast it slips
< 15,000 yearssince it last broke the surface
87quakes of M2.5+ within 10 km since 2016

In plain English

The two sides grind past each other faster than 5 mm a year — more than half a metre (20 inches) every century.

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

The largest earthquake recorded near it was M 7.9 in 1906 (The 1906 San Francisco, California Earthquake) — about 22,000,000 times the energy of an M3.0, the size people start to feel. It released about 11 megatons of TNT.

USGS maps it as 4 sections: Big Sur section, North section, San Gregorio section, Sur Region 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: 0–2.

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

San Andreas faultGreat Valley thrust fault systemFoothills fault systemMaacama faultCalaveras faultHosgri faultHayward faultGreenville faultMonterey Bay- Tularcitos faultZayante-Vergeles faultOrtigalita faultLos Osos faultHunting Creek-Berryessa fault systemRodgers Creek faultSargent faultMonte Vista-Shannon faultButano faultWest Napa faultBennett Valley faultGreen Valley faultAlexander-Redwood Hill faultPfeiffer Point faultEast Monterey Bay faultQuien Sabe faultPiedras Blancas blind faultConcord faultPleasanton faultSan Simeon faultCordelia faultSerra faultTres Pinos faultCorral Hollow-Carnegie faultLas Positas fault M 7.9 · 1906 · The 1906 San Francisco, California Earthquake M 7.4 · 1838 · The 1838 San Andreas Fault, California Earthquake M 6.3 · 1926 · 22 km S of Davenport, California M 6.3 · 1926 · 16 km SW of Davenport, California M 6.2 · 1952 · 28km NW of Cambria, CA
The San Gregorio fault as mapped at the surface (glowing), with the other mapped faults nearby, 87 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 7.9 The 1906 San Francisco, California Earthquake
    April 18, 1906 · epicentre 5 km from the trace
  2. M 7.4 The 1838 San Andreas Fault, California Earthquake
    June 25, 1838 · epicentre 20 km from the trace
  3. M 6.3 22 km S of Davenport, California
    October 22, 1926 · epicentre 4 km from the trace
  4. M 6.3 16 km SW of Davenport, California
    October 22, 1926 · epicentre 10 km from the trace
  5. M 6.2 28km NW of Cambria, CA
    November 22, 1952 · epicentre 3 km from the trace
  6. M 4.7 18km NW of San Simeon, CA
    October 25, 2021 · epicentre 2 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 3 km SSW of San Francisco Zoo, CA
    2026-04-25 · 6 km from the trace
  2. M 2.9 3 km SSW of San Francisco Zoo, CA
    2026-04-25 · 6 km from the trace
  3. M 2.9 13 km NNW of San Simeon, CA
    2026-02-14 · 7 km from the trace
  4. M 2.5 3 km SE of Pacifica, CA
    2026-01-14 · 6 km from the trace
  5. M 2.7 13 km NNW of San Simeon, CA
    2026-01-13 · 6 km from the trace
  6. M 3.0 3 km SSW of Colma, CA
    2025-11-29 · 8 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.