QuakeIndex

Fault · California

San Simeon fault

19 kmlong (12 mi), as mapped
1–5 mm/yrhow fast it slips
< 15,000 yearssince it last broke the surface
35quakes 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.

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

The largest earthquake recorded near it was M 6.2 in 1952 (28km NW of Cambria, CA) — 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

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 faultHosgri faultMonterey Bay- Tularcitos faultLos Osos faultPfeiffer Point faultPiedras Blancas blind fault M 6.2 · 1952 · 28km NW of Cambria, CA
The San Simeon fault as mapped at the surface (glowing), with the other mapped faults nearby, 35 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 28km NW of Cambria, CA
    November 22, 1952 · epicentre 2 km from the trace
  2. M 4.7 18km NW of San Simeon, CA
    October 25, 2021 · epicentre 3 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 2.8 6 km NE of San Simeon, CA
    2026-08-04 · 7 km from the trace
  2. M 2.9 13 km NNW of San Simeon, CA
    2026-02-14 · 5 km from the trace
  3. M 2.7 13 km NNW of San Simeon, CA
    2026-01-13 · 4 km from the trace
  4. M 3.2 15 km NNW of San Simeon, CA
    2025-10-30 · 3 km from the trace
  5. M 3.6 22 km NNW of San Simeon, CA
    2025-08-14 · 7 km from the trace
  6. M 2.7 12 km NNW of San Simeon, CA
    2023-12-29 · 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.