Systematic Assessment of Urban Seismic Risk by Microtremors

微震城市地震风险的系统评估

基本信息

批准号：
04044016
负责人：
KAGAMI Hiroshi
金额：
$ 2.69万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-04044016/
关键词：
Longperiod microtremors Amplification Seismic zonation Los Angeles Seismic input motion

项目摘要

The starting point of an urban seismic disaster mitigation program is to assess seismic input motions in precisely covering a wide area in advance for future earthquakes. This project was two-year plan for developing an easy capable but systematic method for assessment of seismic input motions utilizing long period microtremors measurements. Los Angeles and Sapporo areas are chosen as a model place to realize this project.In the first year of the project, field measurements in the Los Angeles were carried out attending three members from Japan. The following studies were done ;(1)Gathering background data : Accumulating various subsurface data of shallow to deep, an initial 3-dimensional model of the Los Angeles Urban Area is composed. Strong motion records of 1971 San Fernando and 1987 Whitter Narrows earthquakes are collected.(2)Field measurements of microtremors : Microtremors measurements were carried out on more than 150 points covering the whole area. A reference point is set on the baserock site in the north end of the area and continuous measurements are done during the whole period of field measurements. Small earthquake records were also obtained during the period.(3)Analyses of obtained records : Spectral ratio at each site to the baserock site was calculated and two dimensional amplification maps for various period ranges were drawn.In the second year supplemental measurements were done in the Sapporo area in order to propose a new method for systematic assessment of urban seismic risk by microtremors. For this, one member from US was invited to Japan. The procedure using in this project was generalized and a new method was proposed in order to expand the applicability of microtremors measurements to the worldwide.

城市地震灾难缓解计划的起点是评估地震输入动议，以便在未来的地震中精确覆盖广泛区域。该项目是为期两年的计划，用于开发一种易于实用但系统的方法，用于评估使用长期微型人测量的地震输入动作。洛杉矶和萨波罗地区被选为实现这一项目的模型场所。在该项目的第一年，洛杉矶的实地测量值参加了来自日本的三名成员。进行了以下研究；（1）收集背景数据：累积浅层的各种地下数据到深处，洛杉矶市区的初始三维模型被组成。 1971年圣费尔南多（San Fernando）和1987年的强烈运动记录收集了狭窄地震。（2）微晶体的现场测量：微晶体测量值在覆盖整个区域的150点以上进行了测量。在该区域北端的Baserock位点上设置了一个参考点，并在整个现场测量期间进行连续测量。在此期间还获得了小型地震记录。（3）对获得的记录进行分析：计算每个地点与巴斯勒岩地点的光谱比，并绘制了各个期间范围的两个维度扩增图。在第二年进行了补充测量，在萨波罗地区进行了补充测量。为此，我们的一名成员被邀请到日本。该项目中使用的程序已广泛化，并提出了一种新方法，以扩大微型人测量的适用性。