QuakeIndex

Fault · California

Bartlett Springs fault system

160 kmlong (99 mi), as mapped
1–5 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
115quakes 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 5.1 in 2016 (20 km NNE of Upper Lake, California) — about 1,400 times the energy of an M3.0, the size people start to feel. It released about 650 tons of TNT.

USGS maps it as 4 sections: Bartlett Springs section, Elk Creek section, Lake Mountain section, Round Valley 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 systemMaacama faultLittle Salmon faultMad River faultHunting Creek-Berryessa fault systemRodgers Creek faultWest Napa faultBennett Valley faultGreen Valley faultAlexander-Redwood Hill faultNoyo Basin faultKonocti Bay faultBig Valley fault
The Bartlett Springs fault system as mapped at the surface (glowing), with the other mapped faults nearby, 115 of the M2.5+ earthquakes within 10 km of it since 2016 (dots), . 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 5.1 20 km NNE of Upper Lake, California
    August 10, 2016 · epicentre 4 km from the trace
  2. M 4.4 11 km N of Covelo, CA
    July 11, 2026 · epicentre 2 km from the trace
  3. M 4.4 31 km NNW of Covelo, CA
    August 5, 2026 · epicentre 1 km from the trace
  4. M 4.2 9 km NNE of Lake Pillsbury, CA
    March 17, 2025 · epicentre 3 km from the trace
  5. M 4.1 19km NW of Covelo, CA
    November 4, 2021 · epicentre 3 km from the trace
  6. M 4.0 20km ENE of Redway, CA
    April 20, 2021 · 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 2.6 10 km N of Lake Pillsbury, CA
    2026-08-23 · 3 km from the trace
  2. M 2.7 32 km NNW of Covelo, CA
    2026-08-12 · 1 km from the trace
  3. M 2.6 32 km NW of Covelo, CA
    2026-08-10 · 1 km from the trace
  4. M 3.2 31 km NNW of Covelo, CA
    2026-08-08 · 1 km from the trace
  5. M 4.4 31 km NNW of Covelo, CA
    2026-08-05 · 1 km from the trace
  6. M 3.9 31 km NNW of Covelo, CA
    2026-08-05 · 1 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.