Holocene and late Pleistocene slip rates on the San Andreas fault in Yucaipa, California, using displaced alluvial-fan deposits and soil chronology

Research Article| September 01, 1989 Holocene and late Pleistocene slip rates on the San Andreas fault in Yucaipa, California, using displaced alluvial-fan deposits and soil chronology JENNIFER W. HARDEN; JENNIFER W. HARDEN 1US Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar JONATHAN C. MATTI JONATHAN C. MATTI 1US Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar GSA Bulletin (1989) 101 (9): 1107–1117. https://doi.org/10.1130/0016-7606(1989)101<1107:HALPSR>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 JENNIFER W. HARDEN, JONATHAN C. MATTI; Holocene and late Pleistocene slip rates on the San Andreas fault in Yucaipa, California, using displaced alluvial-fan deposits and soil chronology. GSA Bulletin 1989;; 101 (9): 1107–1117. doi: https://doi.org/10.1130/0016-7606(1989)101<1107:HALPSR>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 We derived slip rates on the San Andreas fault from displacement of alluvial fans and from approximate dating of the fans by the degree of soil development. Distinctive red-purple sedimentary rocks of the Miocene(?) Potato Sandstone exposed on Yucaipa Ridge in the San Bernardino Mountains were transported down Wilson Creek and shed across the modern trace of the San Andreas fault. Soils developed in alluvial-fan deposits contain red-purple clasts of the Potato Sandstone and are progressively more developed toward the north-west as a result of fault displacement.We used soil development to estimate the ages of these alluvial fans and underlying deposits. Using dated soils from Cajon Pass and from the Central Valley of California, we estimated ages of Wilson Creek deposits, using a statistical method of maximum likelihood. These methods also utilize Monte Carlo simulations of larger data populations and account for soil variability, uncertainty of calibration dates, and the limited number of soils described and sampled. Resulting age estimates have considerable (as much as 80%) uncertainty, resulting largely from quality of calibration dates.Slip rates for three time intervals were obtained by restoring the medial axis of each displaced fan to Wilson Creek. Maximum slip rates were also obtained by restoring the westernmost extent of each fan to Wilson Creek. Best-estimate rates averaged to the present for 0 to 14,000 yr are 14 to 25 mm/yr; for 0 to 30,000 yr, 22 to 34 mm/yr, and for 0 to 65,000 or 90,000 yr, 12 to 16 mm/yr. Maximum rates averaged to present for 0 to 14,000 yr are as high as 65 mm/yr; older rates are as high as 80 mm/yr. When Holocene rates are accounted for, actual or incremental slip rates for the interval 30,000 to 65,000 or 90,000 yr B.P. are probably 6 to 13 mm/yr. These data tentatively suggest that slip rates on the modern trace have increased during the late Quaternary. Uncertainties in slip and age data, however, allow for rates to have been nearly constant or even decreasing toward the present. 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.