| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025
Abstract
We used shear waves, generated by an air-powered source at the ground surface and recorded in a borehole, to estimate the shear-wave quality factor at strong-motion station Gilroy no. 2. We find similar values of Q using both the decay of the spectra with depth and the slope of the spectral ratio at two depths; we find no evidence of a frequency dependence of Q. The mean value of Q over the depth range 10 to 115 m is close to 10. The use of this value over the depth of the borehole and the observed travel time of 0.358 sec gives a cumulative attenuation factor t* of 0.036 sec for the upper 180 m of the Quaternary alluvium. This is comparable to the differential decay between Gilroy no. 2 and a rock site 1.9 km away (Gilroy no. 1), as measured from the decay of the high-frequency spectra of accelerograms from large earthquakes, plotted on a log-linear scale: t* = 0.05, 0.04, and 0.03 sec for the 1979 Coyote Lake, 1984 Morgan Hill, and 1989 Loma Prieta earthquakes, respectively. The similarity between the attenuations measured from the low-strain surface source and those from the larger amplitude earthquake sources suggests that increases of damping due to nonlinear wave propagation effects are limited.
This article has been cited by other articles:
|
|
 |
|
  K. W. Campbell Estimates of Shear-Wave Q and {kappa}0 for Unconsolidated and Semiconsolidated Sediments in Eastern North America Bulletin of the Seismological Society of America, August 1, 2009; 99(4): 2365 - 2392. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Assimaki, W. Li, J. H. Steidl, and K. Tsuda Site Amplification and Attenuation via Downhole Array Seismogram Inversion: A Comparative Study of the 2003 Miyagi-Oki Aftershock Sequence Bulletin of the Seismological Society of America, February 1, 2008; 98(1): 301 - 330. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Parolai, M. Mucciarelli, M. R. Gallipoli, S. M. Richwalski, and A. Strollo Comparison of Empirical and Numerical Site Responses at the Tito Test Site, Southern Italy Bulletin of the Seismological Society of America, October 1, 2007; 97(5): 1413 - 1431. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Estimated Ground Motion From the 1994 Northridge, California, Earthquake at the Site of the Interstate 10 and La Cienega Boulevard Bridge Collapse, West Los Angeles, California Bulletin of the Seismological Society of America, December 1, 2003; 93(6): 2737 - 2751.
|
|
|
|
|
|
M. C. Chapman, P. Talwani, and R. C. Cannon Ground-Motion Attenuation in the Atlantic Coastal Plain near Charleston, South Carolina Bulletin of the Seismological Society of America, June 1, 2003; 93(3): 998 - 1011. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Estimation of Q for Long-Period (>2 sec) Waves in the Los Angeles Basin Bulletin of the Seismological Society of America, April 1, 2003; 93(2): 627 - 638.
|
|
|
|
|
|
Unexpected Values of Qs in the Unconsolidated Sediments of the Mississippi Embayment Bulletin of the Seismological Society of America, April 1, 2002; 92(3): 1117 - 1128.
|
|
|
|
|
|
Viscoelastic Wave Simulation in Basins by a Variable-Grid Finite-Difference Method Bulletin of the Seismological Society of America, December 1, 2001; 91(6): 1741 - 1749.
|
|
|
|
|
|
Observations of Earthquake Source Parameters at 2 km Depth in the Long Valley Caldera, Eastern California Bulletin of the Seismological Society of America, April 1, 2001; 91(2): 165 - 177.
|
|
|
|
|
|
Probabilistic Seismic Hazard Analysis Considering Nonlinear Site Effect Bulletin of the Seismological Society of America, February 1, 2000; 90(1): 66 - 72.
|
|
|
|
|
|
G. Cultrera, D. M. Boore, W. B. Joyner, and C. M. Dietel Nonlinear soil response in the vicinity of the Van Normal Complex following the 1994 Northridge, California, earthquake Bulletin of the Seismological Society of America, October 1, 1999; 89(5): 1214 - 1231. [Abstract] [PDF]
|
|
|
|
|
|
S. C. Harmsen Determination of site amplification in the Los Angeles urban area from inversion of strong-motion records Bulletin of the Seismological Society of America, August 1, 1997; 87(4): 866 - 887. [Abstract] [PDF]
|
|
|
|
|
|
R. E. Abercrombie Near-surface attenuation and site effects from comparison of surface and deep borehole recordings Bulletin of the Seismological Society of America, June 1, 1997; 87(3): 731 - 744. [Abstract] [PDF]
|
|
|
|
|
|
J. G. Anderson, Y. Lee, Y. Zeng, and S. Day Control of strong motion by the upper 30 meters Bulletin of the Seismological Society of America, December 1, 1996; 86(6): 1749 - 1759. [Abstract] [PDF]
|
|
|
|
|
|
H. Chang and G. A. McMechan Numerical simulation of multi-parameter seismic scattering Bulletin of the Seismological Society of America, December 1, 1996; 86(6): 1820 - 1829. [Abstract] [PDF]
|
|
|
|
|
|
H. van de Vrugt, S. Day, H. Magistrale, and J. Weddberg Inversion of local earthquake data for site response in San Diego, California Bulletin of the Seismological Society of America, October 1, 1996; 86(5): 1447 - 1458. [Abstract] [PDF]
|
|
|
|
|
|
L. Malagnini Velocity and attenuation structure of very shallow soils: Evidence for a frequency-dependent Q Bulletin of the Seismological Society of America, October 1, 1996; 86(5): 1471 - 1486. [Abstract] [PDF]
|
|
|
|
|
|
H.-P. Liu Application of bandlimited anelastic models to wave propagation in highly attenuative media Bulletin of the Seismological Society of America, October 1, 1995; 85(5): 1359 - 1372. [Abstract] [PDF]
|
|
|
|
|
|
L. Malagnini, R. B. Herrmann, G. Biella, and R. de Franco Rayleigh waves in Quaternary alluvium from explosive sources: Determination of shear-wave velocity and Q structure Bulletin of the Seismological Society of America, June 1, 1995; 85(3): 900 - 922. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
