| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Earth Sciences University of Southern California, Los Angeles, California 90089-0740
U.S. Geological Survey, Menlo Park, California 94025
Department of Geology and Geophysics University of Wisconsin-Madison, Madison, Wisconsin 53706
Department of Geology Duke University, Durham, North Carolina 27706
Abstract
Fault-zone guided waves were successfully excited by near-surface explosions in the San Andreas fault zone both at Parkfield and Cienega Valley, central California. The guided waves were observed on linear, three-component seismic arrays deployed across the fault trace. These waves were not excited by explosions located outside the fault zone. The amplitude spectra of guided waves show a maximum peak at 2 Hz at Parkfield and 3 Hz at Cienega Valley. The guided wave amplitude decays sharply with observation distance from the fault trace. The explosion-excited fault-zone guided waves are similar to those generated by earthquakes at Parkfield but have lower frequencies and travel more slowly. These observations suggest that the fault-zone wave guide has lower seismic velocities as it approaches the surface at Parkfield. We have modeled the waveforms as S waves trapped in a low-velocity wave guide sandwiched between high-velocity wall rocks, resulting in Love-type fault-zone guided waves. While the results are nonunique, the Parkfield data are adequately fit by a shallow wave guide 170 m wide with an S velocity 0.85 km/sec and an apparent Q 
30 to 40. At Cienega Valley, the fault-zone wave guide appears to be about 120 m wide with an S velocity 0.7 km/sec and a Q 30.
This article has been cited by other articles:
|
|
 |
|
  L. Knopoff and Y.-T. Chen Single-Couple Component of Far-Field Radiation from Dynamical Fractures Bulletin of the Seismological Society of America, May 1, 2009; 99(2B): 1091 - 1102. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y.-G. Li, P. Chen, E. S. Cochran, J. E. Vidale, and T. Burdette Seismic Evidence for Rock Damage and Healing on the San Andreas Fault Associated with the 2004 M 6.0 Parkfield Earthquake Bulletin of the Seismological Society of America, September 1, 2006; 96(4B): S349 - S363. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. R. Johnson and R. M. Nadeau Asperity Model of an Earthquake: Dynamic Problem Bulletin of the Seismological Society of America, February 1, 2005; 95(1): 75 - 108. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. M. Brocher, G. S. Fuis, W. J. Lutter, N. I. Christensen, and N. A. Ratchkovski Seismic Velocity Models for the Denali Fault Zone along the Richardson Highway, Alaska Bulletin of the Seismological Society of America, December 1, 2004; 94(6B): S85 - S106. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. A. Chavarria, P. Malin, R. D. Catchings, and E. Shalev A Look Inside the San Andreas fault at Parkfield Through Vertical Seismic Profiling Science, December 5, 2003; 302(5651): 1746 - 1748. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Detonation Charge Size versus Coda Magnitude Relations in California and Nevada Bulletin of the Seismological Society of America, October 1, 2003; 93(5): 2089 - 2105.
|
|
|
|
|
|
Seismological Studies at Parkfield IX: Fault-Zone Imaging Using Guided Wave Attenuation Bulletin of the Seismological Society of America, August 1, 2003; 93(4): 1415 - 1426.
|
|
|
|
|
|
Y. Fialko, D. Sandwell, D. Agnew, M. Simons, P. Shearer, and B. Minster Deformation on Nearby Faults Induced by the 1999 Hector Mine Earthquake Science, September 13, 2002; 297(5588): 1858 - 1862. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Hole, R. D. Catchings, K. C. St. Clair, M. J. Rymer, D. A. Okaya, and B. J. Carney Steep-Dip Seismic Imaging of the Shallow San Andreas Fault Near Parkfield Science, November 16, 2001; 294(5546): 1513 - 1515. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Seismological Studies at Parkfield VIII: Modeling the Observed Travel-Time Changes Bulletin of the Seismological Society of America, June 1, 2000; 90(3): 702 - 708.
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
