SEGJ Technical Conference

A gravity survey around the Eastern Boundary Fault Zone of the Shonai Plain

Abstract We have conducted a gravity survey and analysis in and around the eastern boundary fault zone of the Shonai plain (EBFZSP) to reveal subsurface structures and characteristics of the EBFZSP. A gravity survey was carried out in August 2014 and March 2015. The number of measurement points is 177. The steep horizontal gradients and the zero isolines of the vertical differentiation are distributed in the eastern part of the EBFZSP, indicating changes of the subsurface structure caused by the Aosawa fault. Considering above results, together with the two-dimensional density structure along the survey lines obtained in this study, we consider that the EBFZSP has a low-angle east-dipping fault structure derived from the Aosawa fault into the Shonai plain.