Lg Excitation, Attenuation, and Source Spectral Scaling in Central and Eastern North America

摘要

Seismic moments and corner frequencies were obtained for many earthquakes in the central and eastern United States, and for a few events in the western United States, using the Lg phase and a recently developed inversion algorithm. Lg Q values along paths to individual stations were obtained together with source parameters. For moments between 0.15 and 400 x 10 sub 15. NM corner frequencies vary between about 4 and 0.2 Hz while body-wave magnitude varies between about 3.5 and 5.8. Lq Q values decrease from east to west. Maximum and minimum values are 898 and 160, respectively. Lg coda Q values were obtained with excellent coverage in the eastern and western portions of the country and somewhat poorer coverage in the central portion. Lg coda Q is highest (700-750) in portions of New York and Pennsylvania and lower (> 200) in California. Lg coda Q is lower (250-450) everywhere west of the Rocky Mountains than in the rest of the country (450-750). For an earthquake of a given magnitude, Lg and its coda will propagate much more efficiently, and cause damage over a wider area, in the eastern and central United States than in the western United States.