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An offset Holocene stream channel and the rate of slip along the northern reach of the San Jacinto fault zone, San Bernardino Valley, California

1991; Geological Society of America; Volume: 103; Issue: 5 Linguagem: Inglês

10.1130/0016-7606(1991)103 2.3.co;2

1943-2674

Steven G. Wesnousky, C. S. Prentice, Kerry Sieh,

Seismic Waves and Analysis

Research Article| May 01, 1991 An offset Holocene stream channel and the rate of slip along the northern reach of the San Jacinto fault zone, San Bernardino Valley, California STEVEN G. WESNOUSKY; STEVEN G. WESNOUSKY 1Center for Neotectonic Studies, Mackay School of Mines, University of Nevada, Reno, Nevada 89557 Search for other works by this author on: GSW Google Scholar CAROL S. PRENTICE; CAROL S. PRENTICE 2Division of Geological Sciences, California Institute of Technology, Pasadena, California 91125 Search for other works by this author on: GSW Google Scholar KERRY E. SIEH KERRY E. SIEH 2Division of Geological Sciences, California Institute of Technology, Pasadena, California 91125 Search for other works by this author on: GSW Google Scholar Author and Article Information STEVEN G. WESNOUSKY 1Center for Neotectonic Studies, Mackay School of Mines, University of Nevada, Reno, Nevada 89557 CAROL S. PRENTICE 2Division of Geological Sciences, California Institute of Technology, Pasadena, California 91125 KERRY E. SIEH 2Division of Geological Sciences, California Institute of Technology, Pasadena, California 91125 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 (5): 700–709. https://doi.org/10.1130/0016-7606(1991)103 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 Email Permissions Search Site Citation STEVEN G. WESNOUSKY, CAROL S. PRENTICE, KERRY E. SIEH; An offset Holocene stream channel and the rate of slip along the northern reach of the San Jacinto fault zone, San Bernardino Valley, California. GSA Bulletin 1991;; 103 (5): 700–709. doi: https://doi.org/10.1130/0016-7606(1991)103 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 The three-dimensional geometry of a buried channel-fill deposit that crosses, and is offset by, a strand of the San Jacinto fault zone in San Bernardino, California, is reconstructed from an extensive suite of trench logs. The reconstruction shows that the original course of the channel was deflected for a short distance along strike of the fault before it was offset. As a result, apparent offset of the channel deposit across the fault zone is about 12 m in a right-lateral sense, but only 3.5 to 6 m of the apparent offset is due to fault slip. The age of the deposit is ≤1931 ± 109 yr B.P. based on radiometric dating of detrital charcoal collected from the unit. Our excavations do not encompass all active strands of the fault at this site. Hence, our study points to a minimum slip rate of 1.7 to 3.3 mm/yr along the northern San Jacinto fault zone. Historical records show that it has been at least 64 to 90 yr since the last large earthquake occurred along the northern San Jacinto fault. It can thus be inferred from our estimate of fault slip rate that at least 10 to 30 cm of slip is currently stored along the northern segment of the San Jacinto fault. Because prior studies along the same fault zone to the southeast indicate much higher slip rates (on the order of 10 mm/yr), and coseismic offsets for the largest historical earthquakes along the San Jacinto fault zone have been on the order of 30 cm, it is inferred that the northern reach of the San Jacinto fault is now in the later stages of the strain accumulation cycle prior to a moderate to large M 6-7 earthquake. Additionally, the complex geometry of the reconstructed channel serves to illustrate the caution that must be exercised when determining the true offset of buried channel deposits. 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.