HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Lindvall, S. C. Articles by Bowman, K. W. Search for Related Content GeoRef GeoRef Citation

Evidence for Two Surface Ruptures in the Past 500 Years on the San Andreas Fault at Frazier Mountain, California

William Lettis & Associates, Inc.
28470 Avenue Stanford, Suite 120
Valencia, California 91355
(S.C.L., J.G.H., K.W.B.)

Department of Geological Sciences
San Diego State University
San Diego, California 92182
(T.K.R.)

U.S. Geological Survey
345 Middlefield Road, MS 977
Menlo Park, California 94025
(T.E.D.)

We conducted paleoseismic studies in a closed depression along the San Andreas fault on the north flank of Frazier Mountain near Frazier Park, California. We recognized two earthquake ruptures in our trench exposure and interpreted the most recent rupture, event 1, to represent the historical 1857 earthquake. We also exposed evidence of an earlier surface rupture, event 2, along an older group of faults that did not rerupture during event 1. Radiocarbon dating of the stratigraphy above and below the earlier event constrains its probable age to between A.D. 1460 and 1600. Because we documented continuous, unfaulted stratigraphy between the earlier event horizon and the youngest event horizon in the portion of the fault zone exposed, we infer event 2 to be the penultimate event. We observed no direct evidence of an 1812 earthquake in our exposures. However, we cannot preclude the presence of this event at our site due to limited age control in the upper part of the section and the possibility of other fault strands beyond the limits of our exposures. Based on overlapping age ranges, event 2 at Frazier Mountain may correlate with event B at the Bidart fan site in the Carrizo Plain to the northwest and events V and W4 at Pallett Creek and Wrightwood, respectively, to the southeast. If the events recognized at these multiple sites resulted from the same surface rupture, then it appears that the San Andreas fault has repeatedly failed in large ruptures similar in extent to 1857.

This article has been cited by other articles:

				G. E. Hilley and J. J. Young Deducing Paleoearthquake Timing and Recurrence from Paleoseismic Data, Part I: Evaluation of New Bayesian Markov-Chain Monte Carlo Simulation Methods Applied to Excavations with Continuous Peat Growth Bulletin of the Seismological Society of America, February 1, 2008; 98(1): 383 - 406. [Abstract] [Full Text] [PDF]

				G. E. Hilley and J. J. Young Deducing Paleoearthquake Timing and Recurrence from Paleoseismic Data, Part II: Analysis of Paleoseismic Excavation Data and Earthquake Behavior along the Central and Southern San Andreas Fault Bulletin of the Seismological Society of America, February 1, 2008; 98(1): 407 - 439. [Abstract] [Full Text] [PDF]

				G. P. Biasi and R. J. Weldon II Estimating Surface Rupture Length and Magnitude of Paleoearthquakes from Point Measurements of Rupture Displacement Bulletin of the Seismological Society of America, October 1, 2006; 96(5): 1612 - 1623. [Abstract] [Full Text] [PDF]

				N. A. Toke, J R. Arrowsmith, J. J. Young, and C. J. Crosby Paleoseismic and Postseismic Observations of Surface Slip along the Parkfield Segment of the San Andreas Fault Bulletin of the Seismological Society of America, September 1, 2006; 96(4B): S221 - S238. [Abstract] [Full Text] [PDF]

				S. Hecker, D. Pantosti, D. P. Schwartz, J. C. Hamilton, L. M. Reidy, and T. J. Powers The Most Recent Large Earthquake on the Rodgers Creek Fault, San Francisco Bay Area Bulletin of the Seismological Society of America, June 1, 2005; 95(3): 844 - 860. [Abstract] [Full Text] [PDF]

				San Andreas Fault Zone, California: M >=5.5 Earthquake History Bulletin of the Seismological Society of America, October 1, 2002; 92(7): 2555 - 2601.

				Evidence for Large Earthquakes on the San Andreas Fault at the Wrightwood, California, Paleoseismic Site: A.D. 500 to Present Bulletin of the Seismological Society of America, October 1, 2002; 92(7): 2726 - 2760.

				Paleoseismology of the San Andreas Fault at Plunge Creek, near San Bernardino, Southern California Bulletin of the Seismological Society of America, October 1, 2002; 92(7): 2803 - 2840.