科研之友
微信
新浪微博
Facebook
分享链接
摘要
Knowledge of the acceleration spectral shape is crucial to various applications in engineering seismology. Spectral amplitude decays rapidly at high frequencies. Anderson and Hough (1984) introduced the empirical factor kappa to model this attenuation. This is the first time kappa is studied in a vertical array consisting of more than two stations. We use 180 earthquakes recorded at a downhole array with five stations in soils and rock to investigate the effect of soil conditions on kappa. Given that kappa computation processes vary across literature when following the classic Anderson-Hough method, we investigate its variability with the different assumptions that can be made when applying the method. The estimates of kappa(0) range between 0.017 and 0.031 s at the surface and between 0.004 and 0.024 s at rock. This variability due to the assumptions made is larger than the error of each estimate and larger than the average difference in values between sediment and rock. For this data set, part of it can be attributed to the type of distance used. Given this variability, kappa(0) values across literature may not always be comparable; this may bias the results of applications using kappa(0) as an input parameter, such as ground-motion prediction equations. We suggest ways to render the process more homogeneous. We also find that kappa at rock level is not well approximated by surface records from which we deconvolved the geotechnical transfer function. Finally, we compute kappa on the vertical component and find a dependence of the vertical-to-horizontal kappa ratio on site conditions.
- 出版日期2013-4
