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

J. Ramón Arrowsmith*, Olaf Zielke

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

177 Scopus citations


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
Issue number1-2
StatePublished - Dec 1 2009
Externally publishedYes

Bibliographical note

Funding Information:
We thank Elizabeth Zima (neé Stone) for her careful Cholame segment mapping and compilation. Jeri Young's (re)consideration of features near LY4 was valuable. Vince Matthews, George Hilley, and others made important contributions to the mapping. The Twisselmans, Sills, and Pritchards generously permitted us access to their land. We also thank Dallas Rhodes and Nathan Toké for the insightful geomorphologic and paleoseismological discussions. The B4 project is a bold concept that produced amazing data. Thanks to Mike Bevis, Ken Hudnut, and the numerous others at the Ohio State University, US Geological Survey, the National Center for Airborne Laser Mapping, and UNAVCO. This research was motivated by capabilities available through the GEON LiDAR Workflow. Thanks to Chris Crosby for sharing that vision and for numerous discussions about the tectonic geomorphology of the SAF as manifest in LiDAR topography. Reviews by Hisao Kondo, Richard Whittecar, and Takashi Oguchi were very helpful. This effort was supported partially by NSF grants (EAR-0225543, EAR-0310357, EAR-0409745, and EAR-0711282), GeoEarthscope, and the Southern California Earthquake Center (SCEC).


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

ASJC Scopus subject areas

  • Earth-Surface Processes


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