Geological structure of the Pleistocene Shimosa Group revealed by three-dimensional geological modeling in Tsukuba City and its surroundings, Ibaraki Prefecture

Abstract

We present a three-dimensional geological model that reveals the detailed geological structures beneath Tsukuba City and the surrounding area in Ibaraki Prefecture, Japan. This model was created using numerous borehole logs and is based on the stratigraphic framework of Sakata et al. (2018). It shows the distribution of a buried valley filled by the lower part of the Kioroshi Formation (MIS 5e). As the valley-fill deposits consist mainly of soft muddy sediments with low N-values, a detailed understanding of the deposits is required for geological risk assessment. The model enables an intuitive understanding of the subsurface geological structures and can help non-expert stakeholders, including citizens and government officials, understand geological and geotechnical issues. In addition, as the model is provided in a digital format, it is compatible with urban digital transformation including smart cities, and will promote the social implementation of geological and geotechnical data.