60 k.y. record of extension across the western boundary of the Basin and Range province: Estimate of slip rates from offset shoreline terraces and a catastrophic slide beneath Lake Tahoe
- G.M. Kent1,
- J.M. Babcock1,
- N.W. Driscoll1,
- A.J. Harding1,
- J.A. Dingler1,
- G.G. Seitz2,
- J.V. Gardner3,
- L.A. Mayer3,
- C.R. Goldman4,
- A.C. Heyvaert4,
- R.C. Richards4,
- R. Karlin5,
- C.W. Morgan6,
- P.T. Gayes7 and
- L.A. Owen8
- 1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA
- 2Department of Geological Sciences, San Diego State University, San Diego, California 92182, USA
- 3Center for Coastal and Ocean Mapping, University of New Hampshire, Durham, New Hampshire 03824, USA
- 4Department of Environmental Science and Policy, University of California, Davis, California 95616, USA
- 5Department of Geological Sciences, University of Nevada, Reno, Nevada 89557, USA
- 6AVALEX Inc., South Lake Tahoe, California 96155, USA
- 7Center for Marine Studies and Wetlands, Coastal Carolina University, Conway, South Carolina 29526, USA
- 8Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA
Abstract
Deformation across three major fault strands within the Lake Tahoe basin has been mapped by using a novel combination of high-resolution seismic chirp, airborne laser-and acoustic-multibeam–derived bathymetry, and deep- and shallow-water sediment cores. Submerged erosional terraces of late Pleistocene age (19.2 ± 1.8 ka) record vertical deformation across fault strands that ranges between 10 and 15 m; offset of 10 m is observed across the southern part of the West Tahoe fault. Avalanche deposits from the catastrophic McKinney Bay slide (ca. 60 ka) are offset across the Stateline fault by at least 21–25 m. The submerged shoreline terraces and debris avalanche provide marker beds with which to constrain the extensional history of the region for the past 60 k.y. This history is then used to assess the future seismic hazard of the region. Data on deformation across these two important marker beds, combined with chronological control from 14C and optically stimulated luminescence measurements, yield an estimate of extension across the Lake Tahoe basin that is 0.4–0.5 mm/yr. On the basis of these measurements, there exists the potential for a large, seiche wave–generating M7 earthquake every ∼3 k.y. Late Pleistocene and Holocene vertical deformation rates within the Tahoe basin are characteristic of Basin and Range faulting and place the Tahoe basin within the western limits of the extensional Basin and Range province.
Footnotes
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↵GSA Data Repository item 2005068, Table DR1 and Figures DR1 and DR2, dating results, core photographs, chirp profiles; Appendix DR1, data and methods; and Appendix DR2, optically stimulated luminescence dating, is available online at www.geosociety.org/pubs/ft2005.htm, or on request from editinggeosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301-9140, USA.
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- Accepted 17 January 2005.
- Received 24 September 2004.
- Revision received 13 January 2005.
- Geological Society of America
