The SPatial Auto − Correlatlon ( SPAC )method apphed fbr array records ( ) fmicrotremors provides a S − wavc velocity st 田 cture by surface wave inversion with suficient accuracy . The cmciency ofthe SPAC method has mostly been verificd fbr re ] ativc ] y deep underground structures as a tool of geophysical prospecting . However , e 伍brts to incrcase its accuracy and develop the tools fc )r measurements and analysis ar 巳 still necessary fbr extending and applying the method in practical engin ¢

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... ering use , especially for determining shallow velocity structures . We carried out ' array measurernents of microtrcrnors at 7 sites around Kanto area in 亅 apan , where strong − motion stations have already been installed and the underground structures have been dete incd by other methods , such as PS logging and / or reflection survey 、 Through the comparison or S− wav ¢ ve 【 ocity structures by various methods , we c 跚 concludc that the SPAC method has sufficient precision in practical engineering use . Arohiteotural エnstitute of Japan .