Record #00413Nature archive
The San Andreas Fault is California's longest fault, described by NASA Earth Observatory as about 1,200 kilometres long. USGS describes the broader fault system as roughly 1,300 kilometres, reflecting a different system-level scope.
Current Record
about1,200km
Current record value
The San Andreas is a right-lateral strike-slip fault network marking the boundary between the Pacific and North American plates across much of California. The geological fault is not visibly exposed as a continuous cliff or scar along its entire length, and its branches vary in structure and accessibility.
NASA's satellite and radar-topography presentation of the Carrizo Plain explicitly identifies the approximately 1,200-kilometre San Andreas as the longest fault in California. USGS describes the San Andreas Fault System as a roughly 1,300-kilometre transform boundary. The approximately 350-kilometre rupture in 1857 was an event-specific rupture, not a measure of the entire fault's length.
The record conclusion has sufficient verification support.
Basis: direct confirmation by an authority
NASA Earth Observatory's 2000 San Andreas Fault in the Carrizo Plain article explicitly identifies the approximately 1,200-km San Andreas as California's longest fault, supporting both the regional comparison and the recorded length. A 2018 USGS study describes the broader fault system as about 1,300 km; these figures should not be represented as the same precisely defined measurement. Exposed surface faulting is prominent locally, not throughout the entire system.
This is a California regional record, not the world's longest fault. NASA's roughly 1,200-km figure and USGS's roughly 1,300-km system-wide estimate have differing scope. Total fault length must not be presented as a continuously visible exposed surface trace.
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