社団法人 物理探査学会
第129回(平成25年度秋季)学術講演会


地下水等総合観測点(愛媛県新居浜観測井)周辺の地下構造調査

講演要旨(和文)
産総研は東南海・南海地震の予測のために,東海から四国地方の16地点に地震地下水等総合観測施設を整備した.水位計,歪計,地震計などが坑井内に設置され,併せて構造調査,検層,応力測定なども実施された.最近の構造調査は愛媛県の新居浜地点で行われた.測線は長さ約10劼如た卦鑄祐兮点付近を通り,中央構造線の活断層に交差する.反射断面で,三波川変成岩と和泉層群の地質境界である石鎚断層は明瞭にイメージされ北に傾斜する.和泉層群はあまりよく認識されず,岡村断層は反射面の不連続性に基づいて解釈した.

講演要旨(英文)
AIST has equipped sixteen groundwater observation stations with measuring instruments between the Tokai and the Shikoku district to predict the Tonankai/Nankai earthquake. Water gauge, strain gauge and seismometer etc. were installed in bore holes. Subsurface structure survey, well logging and stress measurement etc. were also conducted at each station. The latest subsurface structure survey was conducted at Niihama station in Ehime Prefecture. The survey line is 10 km long, runs near the station and crosses several active faults of the Median Tectonic Line. The Ishizuchi fault, terrain boundary between the Sambagawa metamorphic rocks and the Izumi group, is clearly imaged and it dips northward in the seismic section. The Izumi group is not recognized well and the Okamura fault is interpreted on the basis of discontinuities of reflectors.