HR: 1340h
AN: S23B-0308    [Abstracts]
TI: Estimation of Local Site Effects Using Coda Waves
AU: * Su, F
EM: feng@seismo.unr.edu
AF: Seismological Lab.,, University of Nevada-Reno, Reno, NV 89557 United States
AB: Since the pioneering work of Aki (1969), many theoretical and observational studies have been made using coda waves of local seismic events. This has led to great progress in understanding seismic wave scattering as well as to a variety of practical applications (Aki and Chouet, 1975; Chouet et al., 1978; Phillips and Aki, 1986; Zeng et al., 1991; Su et al., 1991; Sato and Fehler, 1998; Mayeda et al., 2003). The fundamental characteristic of coda waves is that their decay depends only on the average properties of the region surrounding the source and station, not on any particular wave path. This property leads to a separability of source, path and site effects on coda waves and offers an effective means for determining the site amplification factor empirically. By comparing the results from direct S waves and coda waves, many studies have shown that coda waves provide more stable estimates of site amplification and coda amplification factor represents that of S waves averaged over various directions of wave propagations (Tsujiura, 1978; Tucker and King, 1984; Su et al., 1996; Bonilla et al., 1997;). On the regional scale, Su and Aki (1995) have established uniformly estimated site amplification factors throughout central and southern California with a common reference using coda waves recorded from local earthquakes. They found that coda site amplifications are well correlated with surface geology. The recent study by Zhang (2004) found a systematic correlation between coda-wave site amplification and NEHRP site classification using digital strong-motion and broadband network recordings of the Chi-Chi, Taiwan earthquake and its aftershock sequences. The results are useful for UBC and IBC design codes. Under the current plan of Earthscope's USArray deployment, a transportable telemetered seismic array will roll across the United States with 1-2 year deployments at each site and will cover the entire continental United States over a period of 8-10 years. The data collected from USArray plus recordings from ANSS and other regional and local networks will be of great importance to study site effect nationwide. This large body of data will offer a great opportunity to establish uniformly estimated site-amplification factors throughout the United States with a common reference.
DE: 7200 SEISMOLOGY
DE: 7212 Earthquake ground motions and engineering
SC: Seismology [S]
MN: 2004 AGU Fall Meeting