SEGJ Technical Conference

An overview of geophysical exploration project on the coastal area of Horonobe, Japan

Abstract Geophysical techniques for investigating geological structure, fault structure, and ground water condition beneath coastal areas are demanded for site characterization of nuclear waste depository. Particularly, electromagnetic techniques need significant improvement so that they could be successfully applied to very shallow water environment. As a preliminary research for these purposes, we have conducted geophysical studies in the coastal zone of the Horonobe area, Hokkaido, in FY 2007. They include MT/AMT and TEM soundings on land and hydrological interpretation of geophysical logging data. We have also developed a prototype marine EM receiver for shallow water measurement. Resistivity models obtained from MT/AMT data indicate that high-resistivity Quaternary sediments are underlain by very low-resistivity Quaternary-Neogene sedimentary layers. The latter formations seem to contain fossil salt water.