QuakeIndex

Fault · California

Alexander-Redwood Hill fault

36 kmlong (22 mi), as mapped
not measuredhow fast it slips
< 15,000 yearssince it last broke the surface
29quakes of M2.5+ within 10 km since 2016

In plain English

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

The largest earthquake recorded near it was M 4.4 in 2022 (3km N of Santa Rosa, CA) — about 120 times the energy of an M3.0, the size people start to feel. It released about 58 tons of TNT.

This week vs. its last ten years

75/100

elevated

1 quake of M1.5+ within 5 km of the trace in the last 7 days — busier than 75% of weeks since 2016. A normal week: 0–1.

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

San Andreas faultGreat Valley thrust fault systemBartlett Springs fault systemMaacama faultGreenville faultHunting Creek-Berryessa fault systemRodgers Creek faultWest Napa faultBennett Valley faultGreen Valley faultKonocti Bay faultConcord faultCordelia faultBig Valley fault
The Alexander-Redwood Hill fault as mapped at the surface (glowing), with the other mapped faults nearby, 29 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 4.4 3km N of Santa Rosa, CA
    September 14, 2022 · epicentre 6 km from the trace
  2. M 4.3 4km N of Santa Rosa, CA
    September 14, 2022 · epicentre 5 km from the trace
  3. M 4.2 8 km ESE of Cloverdale, CA
    July 29, 2026 · epicentre 5 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 3.3 3 km ESE of Larkfield-Wikiup, CA
    2026-09-03 · 3 km from the trace
  2. M 2.6 7 km ESE of Cloverdale, CA
    2026-08-04 · 6 km from the trace
  3. M 2.7 8 km ESE of Cloverdale, CA
    2026-08-01 · 5 km from the trace
  4. M 2.8 7 km ESE of Cloverdale, CA
    2026-08-01 · 4 km from the trace
  5. M 3.7 7 km ESE of Cloverdale, CA
    2026-08-01 · 5 km from the trace
  6. M 3.0 7 km ESE of Cloverdale, CA
    2026-07-29 · 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.