期刊
BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA
卷 93, 期 2, 页码 627-638出版社
SEISMOLOGICAL SOC AMER
DOI: 10.1785/0120020135
关键词
-
We simulate 0- to 0.5-Hz 3D wave propagation through the Southern California Earthquake Center seismic velocity reference model, version 2, for the 1994 Northridge earthquake in order to examine the effects of anelastic attenuation and amplification within the near-surface sediments. We use a fourth-order finite-difference staggered-grid method with the coarse-grained frequency-independent anelastic scheme of Day and Bradley (2001) and a variable slip distribution from kinematic inversion for the Northridge earthquake. We find that the near-surface material with S-wave velocity (V-s) as low as 500 m/sec significantly affects the long-period peak ground velocities, compared with simulations in which the S-wave velocity is constrained to 1 km/sec and greater. Anelastic attenuation also has a strong effect on ground-motion amplitudes, reducing the predicted peak velocity by a factor of up to 2.5, relative to lossless simulations. Our preferred Q model is Q(s)/V-s = 0.02 (V-s in meters per second) for V-s less than 1-2 km/sec, and much larger Q(s)/V-s (0.1, V, in meters per second) for layers with higher velocities. The simple model reduces the standard deviation of the residuals between synthetic and observed natural log of peak velocity from 1.13 to 0.26, relative to simulations for the lossless case. The anelastic losses have their largest effect on short-period surface waves propagating in the Los Angeles basin, which are principally sensitive to Q(s) in the low-velocity, near-surface sediments of the basin. The low-frequency ground motion simulated here is relatively insensitive to Q(p), as well as to the values of Q(s) at depths greater than roughly that of the 2-km/sec S-wave velocity isosurface.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据