Abstract
The two Lake Ohara-Yauneyamanishi and the Iwakuni-Kamine active fault systems are defined as zones composed of active and geologic faults, in the western Chugoku District, based on the distributions of lineaments, geologic faults, and active faults. The Kikugawa and Shibuki faults, which have been previously recognized, are relatively large-scale active faults outside the active fault systems. The average release-rate of the seismic moments of the active faults and fault systems is calculated from the magnitude of destructive inland earthquakes or the average slip-rate of active faults. The amount of seismic moments is given from the calculated average release-rate multiplied by the elapsed period from the latest earthquake event to the present. The magnitude of the probable earthquake that would occur along the active fault or fault system in 1997, which is described as a magnitude potential of the probable earthquake, is converted from the amount of seis mic moments. Taking the obtained magnitude potential into account, the risk of destructive inland earthquakes is assessed for each active fault or fault system, and the assessment is also discussed.
