QuakeIndex

Fault · California

Butano fault

45 kmlong (28 mi), as mapped
not measuredhow fast it slips
last 150 yearssince it last broke the surface
14quakes of M2.5+ within 10 km since 2016

In plain English

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

The largest earthquake recorded near it was M 7.4 in 1838 (The 1838 San Andreas Fault, California Earthquake) — about 4,000,000 times the energy of an M3.0, the size people start to feel. It released about 1.9 megatons of TNT.

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 faultFoothills fault systemCalaveras faultHayward faultGreenville faultMonterey Bay- Tularcitos faultZayante-Vergeles faultSargent faultMonte Vista-Shannon faultEast Monterey Bay faultQuien Sabe faultPleasanton faultSerra faultTres Pinos faultCorral Hollow-Carnegie faultLas Positas fault M 7.4 · 1838 · The 1838 San Andreas Fault, California Earthquake M 6.5 · 1865 · South of San Jose, California M 6.2 · 1903 · Near San Jose, California M 6.1 · 1903 · Near San Jose, California
The Butano fault as mapped at the surface (glowing), with the other mapped faults nearby, 14 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 7.4 The 1838 San Andreas Fault, California Earthquake
    June 25, 1838 · epicentre 6 km from the trace
  2. M 6.5 South of San Jose, California
    October 8, 1865 · epicentre 9 km from the trace
  3. M 6.2 Near San Jose, California
    August 3, 1903 · epicentre 23 km from the trace
  4. M 6.1 Near San Jose, California
    June 11, 1903 · epicentre 16 km from the trace
  5. M 4.6 1 km SE of Boulder Creek, CA
    April 2, 2026 · epicentre 7 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 4.6 1 km SE of Boulder Creek, CA
    2026-04-02 · 7 km from the trace
  2. M 2.5 5 km WSW of Portola Valley, CA
    2026-03-14 · 10 km from the trace
  3. M 2.6 5 km WSW of Loyola, CA
    2025-07-08 · 8 km from the trace
  4. M 3.0 5 km WSW of Loyola, CA
    2025-07-08 · 8 km from the trace
  5. M 2.5 5 km SW of Loyola, CA
    2025-07-06 · 8 km from the trace
  6. M 2.8 4 km WSW of Cupertino, CA
    2023-09-22 · 10 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.