权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Fundamental research on attenuation and coherency characteristics of body waves in a sedimentary layer-basement system

沉积层-基底体系体波衰减及相干特性基础研究

基本信息

批准号：
15560408
负责人：
KINOSHITA Shigeo
金额：
$ 2.3万
依托单位：
Yokohama City University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15560408/
关键词：
Sedimentary laver-basement system Frequencv-dependent Q Qs Qp Direct and surface reflected waves Omega-squared model of coherence Critical corner frequency ω^<-2>型コヒーレンス特性

项目摘要

A fundamental issue in strong-motion seismology and earthquake engineering is to determine the frequency band in which body waves propagate coherently in a sedimentary layer-basement system. To respond this issue, we investigated down-hole array recordings including deep-borehole seismograms obtained in the Kanto region, Japan, and obtained the following results:(1) Coherence characteristics of body waves from local events and traveling in a sedimentary llayer-basement system are empirically modeled by γ^2(f)=γ_0^2/1+(f/f_c)^n, where n is approximately 2.(2) The corner frequency, f_c in the ω^<-2> - model intends to increase with a decrease in travel-time. However, the values of f_c/2 becomes nearly constant, independent of travel time for travel timeless than 2.5 s. In the case of SH-wave, the values of f_c/2 are about 2.5 -3Hz in the travel time range from 0.5 to 2.5 s and the values of γ_0^2 are larger than 0.9. This means that the SH waves in the pre-Tertiary basement are getting on toward incoherent in frequencies higher than 2.5 to 3 Hz and the use of stochastic methods for the study of strong-motion prediction becomes effective in frequencies higher than 2.5 to 3 Hz.(3) In frequencies where body waves propagate coherently in a sedimentary layer-basement system, Q_p(f) and Q_s(f) are approximately proportional to frequency. The average value of Q_s(f)/Q_p(f) is about 1.5 in the frequency band between 0.5 and 2Hz.

强震地震学和地震工程的一个基本问题是确定沉积层-基底体系中体波相干传播的频带。针对这一问题，研究了在日本关东地区获得的包括深孔地震记录在内的井底阵列记录，得到以下结果：(1)沉积层-基底体系中局部事件和传播体波的相干性特征，经验模型为γ^2(f)=γ_0^2/1+(f/f_c)^n，其中n近似为2。(2)在ω^<-2> -模型中，转角频率f_c有随行程时间减小而增大的趋势。然而，f_c/2的值几乎是恒定的，与旅行时间无关，旅行时间超过2.5 s。对于sh波，在0.5 ~ 2.5 s的传播时间范围内，f_c/2的值约为2.5 ~ 3hz， γ_0^2的值大于0.9。这意味着前第三纪基底的SH波在高于2.5 ~ 3hz的频率上趋于非相干，并且在高于2.5 ~ 3hz的频率上使用随机方法进行强震预测研究变得有效。(3)沉积层-基底体系中体波相干传播的频率，Q_p(f)和Q_s(f)近似与频率成正比。在0.5 ~ 2Hz频段内，Q_s(f)/Q_p(f)的平均值约为1.5。