| 講演要旨(和文) | | 本発表では, 茨城県常総市(IBRH10, KIK-NET)で実施したSPACとCCAの比較検討及び安価な地震計を用いたCCAの可能性の検討の為の野外実験の結果を報告する. CCAはSPACとよく一致する分散曲線を与えたが, それは動コイル型速度計L22D及び多チャンネルデータロガーGeodeを使う場合のみならず, より低周波数帯域まで収録可能なフィードバック型速度計VSE12-CCや過減衰型加速度(強震)計JEP6A3及び単チャンネルデータロガーMcSeis-MTを使う場合でも約2.3Hz以上の周波数帯域に限られた. これは, より小さな周波数においては, データロガーの24ビットA/D変換の分解能が, 使用した小規模アレイに対応する微動の伝播に因る小さな位相差を検出するには, 不足である為と考えられる. また, チャンネル間の計器特性の差を補正する必要性を再認識した. |
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| | 講演要旨(英文) | | We conducted a comparative field experiment in Jyoso City, Ibaraki Pref., Japan that is aimed to check the validity of CCA in comparison with SPAC and also to verify the possibility of applying CCA using simple moving coil seismometers. The results showed that in a limited frequency range CCA could provide a similar dispersion curve as that given by the SPAC method and also that using L22D seismometers, Sercel Inc. CCA could provide a similar result. The available frequency range, however, is limited higher than about 2.3 Hz not only in the cases using L22D of which the natural frequency is 2.0 Hz and the digital recorder GEODE, Geometrics Corp. that covers from 1.75Hz to 20 KHz, but also in the cases using VSE12-CC, Tokyo Sokushin Ltd. the feedback type seismometer that covers down to 0.05Hz and McSeis-MT, OYO Corp. the recorder that covers down to DC. This seems due to the resolution of A/D converters that are 24 bits but not enough to record the signals enough correctly to detect small phase difference of microtremor within the used small array in smaller frequency range. Besides, the recognition on the importance of the system characteristics correction is refreshed. |
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