Tectonic geomorphology of the San Andreas Fault zone from high resolution topography: An example from the Cholame segment

Ramon Arrowsmith, Olaf Zielke

Research output: Contribution to journalArticle

124 Scopus citations

Abstract

High resolution topographic data along fault zones are important aids in the delineation of recently active breaks. A 15 km-long portion of the south-central San Andreas Fault (SAF) along the southern Cholame segment contains well preserved tectonic landforms such as benches, troughs, scarps, and aligned ridges that indicate recurring earthquake slip. Recently acquired LiDAR topographic data along the entire southern SAF ("B4" project) have shot densities of 3-4 m- 2. Computed from the LiDAR returns, Digital Elevation Models (DEMs) of 0.25 to 0.5 m resolution using local binning with inverse distance weighting and 0.8 m or larger search radii depict the tectonic landforms at paleoseismic sites well enough to assess them confidently. Mapping of recently active breaks using a LiDAR-only based approach compares well with aerial photographic and field based methods. The fault zone varies in width from meters to nearly 1 km and is comprised of numerous en echelon meter to kilometer-length overlapping sub parallel fault surfaces bounding differentially moving blocks that elongate parallel to the SAF. The semantic variations of what constitutes "active" and the importance of secondary traces influence the breadth and complexity of the resulting fault trace maps.

Original languageEnglish (US)
Pages (from-to)70-81
Number of pages12
JournalGeomorphology
Volume113
Issue number1-2
DOIs
StatePublished - Dec 1 2009

Keywords

  • Digital Elevation Models
  • LiDAR
  • San Andreas Fault
  • Tectonic geomorphology

ASJC Scopus subject areas

  • Earth-Surface Processes

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