QuakeIndex

Fault · California

Sierra Madre fault

128 kmlong (80 mi), as mapped
> 5 mm/yrhow fast it slips
last 150 yearssince it last broke the surface
101quakes 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 7.5 in 1812 (Northwest of San Bernardino, California) — about 5,600,000 times the energy of an M3.0, the size people start to feel. It released about 2.7 megatons of TNT.

USGS maps it as 8 sections: Clamshell-Sawpit section, Cucamonga section, San Fernando section, Santa Susana section, Sierra Madre B section, Sierra Madre C section, Sierra Madre D section, Sierra Madre E 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: 0–1.

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

San Andreas faultElsinore faultGarlock faultSan Jacinto faultNewport-Inglewood-Rose Canyon faultSan Clemente faultSanta Ynez faultLenwood-Lockhart faultHelendale-South Lockhart faultSan Gabriel faultCalico-Hidalgo faultPitas Point faultCatalina faultPalos Verdes faultOak Ridge fault (offshore)Mission Ridge fault systemSan Pedro Basin faultNorth Frontal thrust systemSanta Cruz Island faultHarper faultMalibu Coast faultSanta Cruz faultDume faultOak Ridge faultSimi-Santa Rosa faultPuente Hills blind thrust systemSan Cayetano faultRed Mountain faultSan Gorgonio Pass faultPleito faultSanta Monica faultNorthridge blind thrustSan Joaquin Hills thrustCleghorn faultRaymond faultCrafton Hills faultVerdugo faultMt. General faultBanning faultHollywood faultVentura faultRed Hill-Etiwanda Avenue faultBeaumont Plain fault M 7.5 · 1812 · Northwest of San Bernardino, California M 6.6 · 1971 · 1971 San Fernando Earthquake, California M 6.4 · 1899 · Cajon Pass area, northwest of San Bernardino, California M 6.2 · 1923 · 3 km SE of San Bernardino, California M 6.2 · 1894 · Northwest of San Bernardino, California M 6.0 · 1769 · Greater Los Angeles area, California
The Sierra Madre fault as mapped at the surface (glowing), with the other mapped faults nearby, 101 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 7.5 Northwest of San Bernardino, California
    December 8, 1812 · epicentre 22 km from the trace
  2. M 6.6 1971 San Fernando Earthquake, California
    February 9, 1971 · epicentre 9 km from the trace
  3. M 6.4 Cajon Pass area, northwest of San Bernardino, California
    July 22, 1899 · epicentre 14 km from the trace
  4. M 6.2 3 km SE of San Bernardino, California
    July 23, 1923 · epicentre 20 km from the trace
  5. M 6.2 Northwest of San Bernardino, California
    July 30, 1894 · epicentre 14 km from the trace
  6. M 6.0 Greater Los Angeles area, California
    July 28, 1769 · epicentre 25 km from the trace
  7. M 4.4 4km N of La Verne, CA
    August 29, 2018 · epicentre on the trace
  8. M 4.4 6 km NW of Rialto, CA
    July 31, 2025 · 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 2.6 9 km SW of Valencia, CA
    2026-08-12 · 5 km from the trace
  2. M 2.5 1 km NE of Fillmore, CA
    2026-05-02 · 10 km from the trace
  3. M 2.7 6 km NW of Rialto, CA
    2026-04-16 · 5 km from the trace
  4. M 2.8 10 km SSW of Valencia, CA
    2026-02-08 · 4 km from the trace
  5. M 2.9 7 km NNE of Fontana, CA
    2026-01-19 · 3 km from the trace
  6. M 2.5 4 km SE of Lytle Creek, CA
    2026-01-18 · 6 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.