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1 Department of Geological
Sciences
Arizona State University Box 871404
Tempe, Arizona
85287-1404
Nathan.toke{at}asu.edu
ramon.arrowsmith{at}asu.edu
Historically, the Parkfield segment has represented a transition in fault
behavior along the San Andreas fault (SAF). Despite a
33 mm/yr
long-term slip rate along the SAF, slip has not been observed on the
Cholame segment since the great 1857 Fort Tejón earthquake. During that
time, the Parkfield segment has experienced slip from at least six
M
6.0 earthquakes, aseismic fault creep, and from minor earthquakes. Data from
aseismic slip-rate studies and historical earthquake studies allow us to
estimate the total slip released along this portion of the SAF since
1857. Assuming the SAF should slip at the long-term slip rate, a slip
deficit of
5 m exists along the Cholame segment since 1857. The slip
deficit is approximately equivalent to 1857 offsets measured on the Cholame and
the southeast portion of the Parkfield segment. Thus, the slip deficit in
southeast Parkfield and Cholame may be as great as the slip accommodated along
these segments in 1857. The slip deficit abruptly decreases to the northwest
across the Parkfield segment. It is < 2 m near the town of Parkfield and
0 m northwest of Middle Mountain. An
M 7 event rupturing all or
part of the Cholame segment and the southeastern Parkfield segment (slip
decreasing to the northwest) would release the accumulated slip and is
plausible. Importantly, this study also shows that the change in the pattern of
strain release occurs in the middle of the Parkfield segment, rather than at its
ends.
Online material: Tables showing aseismic and coseismic slip estimations and calculations.
This article has been cited by other articles:
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R. A. Harris and J R. Arrowsmith Introduction to the Special Issue on the 2004 Parkfield Earthquake and the Parkfield Earthquake Prediction Experiment Bulletin of the Seismological Society of America, September 1, 2006; 96(4B): S1 - S10. [Abstract] [Full Text] [PDF] |
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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] |
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D. D. Jackson and Y. Y. Kagan The 2004 Parkfield Earthquake, the 1985 Prediction, and Characteristic Earthquakes: Lessons for the Future Bulletin of the Seismological Society of America, September 1, 2006; 96(4B): S397 - S409. [Abstract] [Full Text] [PDF] |
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