QuakeIndex

Fault · California

Harper fault

65 kmlong (40 mi), as mapped
not measuredhow fast it slips
< 15,000 yearssince it last broke the surface
21quakes of M2.5+ within 10 km since 2016

In plain English

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

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 faultGarlock faultSouthern Sierra Nevada faultLenwood-Lockhart faultHelendale-South Lockhart faultSan Gabriel faultCalico-Hidalgo faultPanamint Valley faultPisgah-Bullion faultCamp Rock-Emerson-Copper Mountain faultNorth Frontal thrust systemBlackwater faultJohnson Valley faultSouthern Death Valley faultLittle Lake faultManix faultOwl Lake faultMt. General faultRed Pass faultOld Woman Springs faultTank Canyon fault
The Harper fault as mapped at the surface (glowing), with the other mapped faults nearby, 21 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.

Most recent near it

  1. M 3.2 33 km SE of Johannesburg, CA
    2026-04-20 · 1 km from the trace
  2. M 3.2 18 km ESE of Johannesburg, CA
    2026-02-26 · 6 km from the trace
  3. M 3.5 18 km ESE of Johannesburg, CA
    2026-02-26 · 6 km from the trace
  4. M 2.5 18 km ESE of Johannesburg, CA
    2026-02-09 · 6 km from the trace
  5. M 3.1 16 km NNE of Barstow, CA
    2025-02-18 · 10 km from the trace
  6. M 3.5 32 km ENE of Boron, CA
    2025-01-23 · 2 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.