DIGITAL ACTIVE FAULT MAP OF JAPAN AND ITS APPLICATION

The location of active faults is one of the most important data for large seismic activities in the past, earthquake prediction on land and the relevant seismic hazard mitigation. Even in an earthquake country Japan, danger of active faults was not well understood among the people before 1995 Kobe earthquake. In order to provide the fundamental information regarding active faults such as their distribution and characteristic activities, we have re-interpreted air-photographs in Japan and depicted the detailed location of active fault traces together with related information. Active faults we mapped are mostly based on distinctive fault-related features, and therefore are defined as faults that have been repeatedly moved during the last several 100,000 years and will move again in future generating large earthquakes. Many new active faults were found in one side, and many previously recognized faults were regarded inactive in the other side mainly due to detailed interpretation of large-scale air-photographs. The 1:25000 map scale maps containing the active faults amount to 1300 GIJ toposheets and they were not easily published as printed sheets. In order to provide the data to the public in the form that many people can easily utilize, we digitized the data and burned on DVD with GIS map as background, and publish it as ÉÑDigital Active Fault Map of JapanÉÜ. This map reveals types of active faults and frequency in their regional distribution, activity (average slip rates) of fault zones, strain rates under the present stress field, relation between active faults and land use especially public buildings such as school and hospital etc. The map still needs much improvement, but we hope this map will be used not only in the academic fields but also in the land use planning to avoid dangerous setting of structures.