| 講演要旨(和文) | | 富士川河口周辺から富士山麓の南西部周辺では富士川河口断層帯と呼ばれる構造が発達しており，富士川河口の西側には，富士川河口断層帯の南端に位置する入山瀬断層，善福寺断層が存在するとされている．本研究では，富士川河口西岸陸域で浅部地下構造の推定を行うためにLaCoste&Romberg重力計を用いて重力探査を行った．測線は富士川河口西側の沿岸部における東西約5.6 kmの測線①と，河口から内陸に2 km入った所の東西約1.1 kmの測線②とした．調査を行った結果，富士川河口西側沿岸部において，地下の褶曲構造を示唆する密度構造モデルが妥当であると推定した．モデルから，善福寺断層の西側にて陸域から海域にかけて岩淵安山岩類の岩体が分布している可能性が考えられた．また，入山瀬断層から東部にかけて,陸域から海域にかけて連続する高密度の岩体の存在を示す密度構造が見られた． |
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| | 講演要旨(英文) | | Fujikawa-kako faults group is present to the periphery southwest at the foot of Mt. Fuji from around Fujikawa estuary. To the west of Fujikawa River it is said that Iriyamase fault and Zenpukuji fault are located in the southern end of the Fujikawa fault zone. In the present study, it was carried out gravity survey using LaCoste & Romberg gravity meter in order to make an estimate of subsurface structures the west part of Fujikawa River. It was set two Survey line. One was the survey line 1 of the total length 5.6km on coastal areas of Fujikawa estuary west, and the other was the survey line 2 of the total length 1.1km on place went 2 km inland from Fujikawa estuary. As a result of the investigation, we were able to create a density structure model suggests a folded structure of the underground. Looking at the density structure model, there is a possibility of rock body of Iwabuchi andesites over the sea from the land at the west side of the Zenpukuji fault. In addition, eastern from Iriyamase fault, we were able to see the density structure that indicates the high density of the rock body which continuously over the sea from the land. |
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