Bulletin of the Seismological Society of America
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Bulletin of the Seismological Society of America; June 2007; v. 97; no. 3; p. 843-862; DOI: 10.1785/0120060101
© 2007 Seismological Society of America
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Electronic Supplement
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Malagnini, L.
Right arrow Articles by Herrmann, R. B.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation

A Regional Ground-Motion Excitation/Attenuation Model for the San Francisco Region

Luca Malagnini1, Kevin Mayeda2, Robert Uhrhammer3, Aybige Akinci1 and Robert B. Herrmann4

1 Istituto Nazionale di Geofisica e Vulcanologia
00143 Rome, Italy
 (L.M., A.A.)
2 Weston Geophysical Corporation
Lexington, Massachusetts 02420
 (K.M.)
3 University of California Berkeley, California 94720–4767
 (R.U.)
4 Saint Louis University St. Louis, Missouri 63108
 (R.B.H.)

By using small-to-moderate earthquakes located within ~200 km of San Francisco, we characterize the scaling of the ground motions for frequencies ranging between 0.25 and 20 Hz, obtaining results for geometric spreading, Q(f), and site parameters using the methods of Mayeda et al. (2005) and Malagnini et al. (2004). The results of the analysis show that, throughout the Bay Area, the average regional attenuation of the ground motion can be modeled with a bilinear geometric spreading function with a 30-km crossover distance, coupled to an anelastic function exp(–{varpi}fr/[capital greek beta]Q(f), where: Q(f) = 180 f0.42. A body-wave geometric spreading, g(r) = r–1.0, is used at short hypocentral distances (r < 30 km), whereas g(r) = r–0.6 fits the attenuation of the spectral amplitudes at hypocentral distances beyond the crossover.

The frequency-dependent site effects at twelve of the Berkeley Digital Seismic Network stations were evaluated in an absolute sense using coda-derived source spectra. Our results show the following. (1) The absolute site response for frequencies ranging between 0.3 Hz and 2.0 Hz correlate with independent estimates of the local magnitude residuals ({delta}ML) for each of the stations. (2) Moment magnitudes (Mw) derived from our path and site-corrected spectra are in excellent agreement with those independently derived using full-waveform modeling as well as coda-derived source spectra. (3) We use our weak-motion-based relationships to predict motions regionwide for the Loma Prieta earthquake, well above the maximum magnitude spanned by our data set, on a completely different set of stations. Results compare well with measurements taken at specific National Earthquake Hazards Reduction Program site classes. (4) An empirical, magnitude-dependent scaling was necessary for the Brune stress parameter to match the large-magnitude spectral accelerations and peak ground velocities with our weak-motion-based model.

Online material: Tables of peak ground acceleration, peak ground velocity, and pseudo-spectral acceleration at 0.3 sec, 1.0 sec, and 3.0 sec.




This article has been cited by other articles:


Home page
 Bulletin of the Seismological Society of AmericaHome page
S. R. Ford, D. S. Dreger, K. Mayeda, W. R. Walter, L. Malagnini, and W. S. Phillips
Regional Attenuation in Northern California: A Comparison of Five 1D Q Methods
Bulletin of the Seismological Society of America, August 1, 2008; 98(4): 2033 - 2046.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2007 by the Seismological Society of America.