Comparative geometry of the San Andreas fault, California, and laboratory fault zones

Research Article| June 01, 1991 Comparative geometry of the San Andreas fault, California, and laboratory fault zones D. E. MOORE; D. E. MOORE 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar J. D. BYERLEE J. D. BYERLEE 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information D. E. MOORE 1U.S. Geological Survey, Menlo Park, California 94025 J. D. BYERLEE 1U.S. Geological Survey, Menlo Park, California 94025 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1991) 103 (6): 762–774. https://doi.org/10.1130/0016-7606(1991)103<0762:CGOTSA>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation D. E. MOORE, J. D. BYERLEE; Comparative geometry of the San Andreas fault, California, and laboratory fault zones. GSA Bulletin 1991;; 103 (6): 762–774. doi: https://doi.org/10.1130/0016-7606(1991)103<0762:CGOTSA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Textural examination of fault gouge deformed in triaxial friction experiments has revealed differences in the orientations of secondary shear sets between the stably sliding and stick-slip samples. In order to determine whether such differences can be identified in natural faults, maps of recently active breaks along the San Andreas fault from Point Arena to Cajon Pass, California, were examined to compare the types and orientations of secondary structures mapped in the creeping and locked sections. The fault zone was divided into 52 geometrically defined segments of uniform strike, which were then grouped into 7 sections: 4 straight and 2 curved sections, and Cholame Valley. One of the straight sections is the creeping section between San Juan Bautista and Cholame in central California; the rest of the sections are locked. Many of the gross geometric characteristics of the individual segments, such as length, width, and stepover size, reflect their position in either a straight or a curved section. In contrast, with respect to the orientations of the recent breaks within the segments, the single creeping section differs from all of the locked sections, both straight and curved, as follows: (1) the traces of recent breaks with a more west-ward orientation than the local strike of the fault zone (P traces) dominate over those with a more northward orientation (R traces) in the creeping section, whereas the opposite relationship holds in the locked sections, and (2) the more northward-oriented (R) traces make larger angles to the local strike of the fault zone in the locked sections than in the creeping section. The latter result is consistent with the orientations of R shears in our various laboratory samples. The former result was unexpected, because of the predominance of R shears in most laboratory samples, but a small number of samples are analogous to the creeping section in terms of their P-shear abundances, R-shear orientations, and sliding behavior. The causes of these distinguishing characteristics are not yet understood. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.