Combined interpretation of seismic velocity and electrical conductivity using a bimodal mixture model; Application to geophysical logging data in soft sedimentary rock sites at Yokosuka and Horonobe, Japan

Suzuki, Koichi*; Yoshimura, Kimitaka*; Sugita, Yutaka ; Ando, Makoto*; Azuma, Hiroyuki*

One of the benefits of geophysical exploration is that extensive and continuous surveys are possible at low cost, however, the obtained physical properties are chiefly velocity of elastic wave and electrical resistivity. Therefore, it is very important that the techniques can convert geophysical data into quantitative information on the geological environment required for engineering technology. In this study, we have applied an approach that provides estimates of porosity, clay content, and equivalent NaCl concentration based on a combined interpretation of geophysical survey data utilizing an expanded bimodal mixture model. The study used seismic velocity and electrical conductivity data obtained from geophysical logging at two soft sedimentary rock sites, in the muddy or tuffaceous sandstone and mudstone at Yokosuka, and in diatomaceous mudstone and fine sandstone at Horonobe, Japan. The geological information for these sites was successfully estimated.