1:45 PM - 3:15 PM
[O07-P17] Geological structure of Urato Katsurashima Island and Nonoshima Island, Shiogama City
Keywords:Formation
We were interested in the fact that the two strata, the Matsushima Formation and the Otsuka Formation, were clearly exposed during the Urato Geological training in 2019, and considered the geological structure of Nonoshima Island.
In this study, as a continuation of the study, we decided to expand the scope of the study to Katsurashima Island on the west side and interpret the geological structure of the Urato Islands in a wider range.
[Results] It was found that a syncline structure exists in the eastern part of Katsura Island. The syncline axis was south-southeast and the plunge angle was 2 °. As a result of drawing, it was found that there are anticline structures and syncline structures with gentle slopes from Nonoshima to Katsurashima. It was also confirmed that the stratum was lying on its side.
[Discussion] In the history of the formation of the Japanese archipelago, the Matsushima Formation was brought about by volcanic activity and crustal movements caused by the expansion of the Sea of Japan. The location of the slump structure was confirmed in the Matsushima Formation due to the earthquake during deposition. In addition, a normal fault was confirmed as the condition of the pulling field continued. In addition, it is probable that at the point where the overturned stratum was confirmed, the earthquake motion at the stage where this tension field was generated caused a collapse or a submarine landslide in the water.
In this study, as a continuation of the study, we decided to expand the scope of the study to Katsurashima Island on the west side and interpret the geological structure of the Urato Islands in a wider range.
[Results] It was found that a syncline structure exists in the eastern part of Katsura Island. The syncline axis was south-southeast and the plunge angle was 2 °. As a result of drawing, it was found that there are anticline structures and syncline structures with gentle slopes from Nonoshima to Katsurashima. It was also confirmed that the stratum was lying on its side.
[Discussion] In the history of the formation of the Japanese archipelago, the Matsushima Formation was brought about by volcanic activity and crustal movements caused by the expansion of the Sea of Japan. The location of the slump structure was confirmed in the Matsushima Formation due to the earthquake during deposition. In addition, a normal fault was confirmed as the condition of the pulling field continued. In addition, it is probable that at the point where the overturned stratum was confirmed, the earthquake motion at the stage where this tension field was generated caused a collapse or a submarine landslide in the water.