| 講演要旨(和文) | | 地震波干渉法は，異なる受振点で観測された地震波形の相互相関をとることにより，擬似発震記録を合成する手法である．本研究では，反射法探査中に得られた自然地震記録に地震波干渉法の自己相関解析を適用することで，断層やプレート境界の深部構造のイメージングを試みた．反射法探査は2012年富士川河口断層帯から糸魚川−静岡構造線を横断する測線で実施された．地震記録にバンドパスフィルターを適用して不良トレースを除去した後，自己相関係数を計算して擬似ショット記録を合成した．最後にマイグレーションを適用して深度断面を得た．自己相関解析の結果は，深部構造のイメージングには至らなかったが，反射法探査で得られた結果やその解釈と整合的であった．今回行われた反射法探査が自然地震観測に適した観測ではなかったことを考えると，この結果は，地震波干渉法（自己相関解析）のイメージング能力の高さを示していると言える． |
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| | 講演要旨(英文) | | Seismic interferometry synthesizes the pseudo-seismic response by cross-correlating the records observed at different receivers simultaneously. In this study, we applied the auto-correlation analysis of seismic interferometry to the natural earthquake records obtained during a seismic reflection survey. Our objective is to image the deep structure of faults and a plate boundary. The reflection survey was conducted across the Fujikawa-kako fault zone and the Itoigawa-Shizuoka Tectonic line in 2012. In this analysis, first, we applied the band pass filter to the seismic records and removed the traces with low S/N ratio. After we calculated the auto-correlation coefficients of the records, the pseudo-shot records were synthesized. Finally, we applied migration to the reflection record. In our result, deep structures such as the plate boundary were not well imaged. However, our result was consistent with the results of the reflection survey such as migrated section and tomography, and with the geological interpretation, although the survey was not necessarily suitable to observe natural earthquakes. This indicates that seismic interferometry (the auto-correlation analysis) has high potential to image subsurface structures. |
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