Abstract
By taking into account the geological processes of formation of alluvial and diluvial soil deposits, it has been found that the soil deposits are classified into six major types in urban areas in Japan situated on alluvial plains. The same result has been reached by applying a computer technique, which has been developed to simplify an original, complicated boring record in the form of a refined soil profile, to the numerous boring data obtained in city areas which consist of a wide variety of soil conditions. Statistics on thicknesses and N-values are also given for sublayers of soil deposits belonging to each major type and, furthermore, the ranges of predominant periods for strain levels of microtremors and strong-motion earthquakes are evaluated with respect to each type of soil deposits.
