QuakeIndex

Fault · California

Las Positas fault

14 kmlong (9 mi), as mapped
not measuredhow fast it slips
last 150 yearssince it last broke the surface
11quakes 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 6.2 in 1858 (North of San Jose, California) — about 63,000 times the energy of an M3.0, the size people start to feel. It released about 30 kilotons of TNT.

This week vs. its last ten years

Too quiet to rank: fewer than half a year's worth of weeks with any M1.5+ quake within 5 km, in ten years. A single quake here would read as "unusual", so we do not score it.

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 faultOrtigalita faultRodgers Creek faultSargent faultMonte Vista-Shannon faultButano faultWest Napa faultBennett Valley faultGreen Valley faultEast Monterey Bay faultConcord faultPleasanton faultCordelia faultSerra faultCorral Hollow-Carnegie fault M 6.2 · 1858 · North of San Jose, California M 6.0 · 1864 · Alameda County, California
The Las Positas fault as mapped at the surface (glowing), with the other mapped faults nearby, 11 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 6.2 North of San Jose, California
    November 26, 1858 · epicentre 12 km from the trace
  2. M 6.0 Alameda County, California
    March 5, 1864 · epicentre 8 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 13 km SSE of Livermore, CA
    2024-07-12 · 9 km from the trace
  2. M 2.5 7 km SSE of Sunol, CA
    2024-06-04 · 8 km from the trace
  3. M 2.8 6km SE of Pleasanton, CA
    2022-10-31 · 2 km from the trace
  4. M 2.6 6km S of Livermore, CA
    2021-09-01 · 1 km from the trace
  5. M 2.7 10km SE of Livermore, CA
    2020-01-10 · 8 km from the trace
  6. M 2.6 8km SE of Sunol, CA
    2018-12-04 · 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.