QuakeIndex

Fault · California

Maacama fault

160 kmlong (99 mi), as mapped
> 5 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
218quakes 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.

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

The largest earthquake recorded near it was M 5.6 in 2026 (11 km N of Redwood Valley, CA) — about 7,700 times the energy of an M3.0, the size people start to feel. It released about 3.7 kilotons of TNT.

USGS maps it as 2 sections: northern section, southern section.

This week vs. its last ten years

85/100

elevated

4 quakes of M1.5+ within 5 km of the trace in the last 7 days — busier than 85% of weeks since 2016. A normal week: 1–3.

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

San Andreas faultGreat Valley thrust fault systemBartlett Springs fault systemHunting Creek-Berryessa fault systemRodgers Creek faultWest Napa faultBennett Valley faultGreen Valley faultAlexander-Redwood Hill faultNoyo Basin faultKonocti Bay faultBig Valley fault
The Maacama fault as mapped at the surface (glowing), with the other mapped faults nearby, 218 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 5.6 11 km N of Redwood Valley, CA
    June 24, 2026 · epicentre 7 km from the trace
  2. M 5.0 10 km W of Cobb, California
    December 14, 2016 · epicentre 10 km from the trace
  3. M 4.4 9 km ESE of Willits, CA
    January 13, 2026 · epicentre 5 km from the trace
  4. M 4.4 3km N of Santa Rosa, CA
    September 14, 2022 · epicentre 7 km from the trace
  5. M 4.4 13km W of Lakeport, CA
    December 6, 2020 · epicentre 3 km from the trace
  6. M 4.3 8km SE of Talmage, CA
    June 18, 2023 · epicentre 6 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 9 km NW of Redwood Valley, CA
    2026-09-27 · 5 km from the trace
  2. M 2.7 3 km ESE of Santa Rosa, CA
    2026-09-16 · 8 km from the trace
  3. M 3.3 3 km ESE of Larkfield-Wikiup, CA
    2026-09-03 · 5 km from the trace
  4. M 2.6 2 km W of The Geysers, CA
    2026-08-10 · 9 km from the trace
  5. M 2.6 7 km ESE of Cloverdale, CA
    2026-08-04 · 2 km from the trace
  6. M 2.7 8 km ESE of Cloverdale, CA
    2026-08-01 · 4 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.