S-wave velocity structures and ground motion characteristics of loam terraces: The case of the Utsunomiya area, Tochigi Prefecture, central Japan
- 15 June 2020
- journal article
- Published by The Geological Society of Japan in The Journal of the Geological Society of Japan
- Vol. 126 (6), 311-326
- https://doi.org/10.5575/geosoc.2020.0012
Abstract
一般に地盤が良いとされるローム台地において，ローム層が地盤震動特性に与える影響を知るために，栃木県宇都宮地域で段丘面ごとに微動アレイ観測を行った．その結果，調査地域の段丘を覆うローム層はS波速度が130～150m/sと低いこと，また古い段丘ほどローム層が厚いために深度30mまでの平均S波速度は低く，H/Vスペクトルのピーク周波数も低周波側にシフトすることが明らかになった．一方で，鬼怒川や五行川などの河床は主に礫質堆積物からなりローム層を欠くため，河川沿いの低地では平均S波速度は高く，H/Vスペクトルでは高周波にピークがみられた．つまり調査地域では，低地面や低位の段丘ほど堅固な地盤であり，高位の段丘ほどローム層が厚く，軟らかい地盤であるといえる．高位の段丘では，地震の際にやや低周波の揺れが大きく増幅される可能性がある．This publication has 21 references indexed in Scilit:
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