Precaution fault zones designated by Matsuda (1981) are reevaluated using recently-obtained data on the late Quaternary slip-rate and from the result of excavation studies for faults of historical earthquakes. The precaution faults were defined as those with elapse ratio, E=t/R>0.5 (t: elapsed years since the last activity. R: average recurrence interval).
The following three fault z o nes can be excluded from the previously-denoted precaution zones: The Arima-Takatsuki tectonic line (t/R=0.1∼0.4), which have moved in 1596. The Rokko-Awaji fault zone (t/R=0.0∼0.5), of which southern part moved in 1995 and northern part probably in 1586. The Atera fault zone (t/R= 0.3∼0.5 for M8.0 ), which have moved in 1586.
The following fault zones are ascertained to be precaution faults. Segments of the Median Tectonic Line of central Shikoku to central Kii (t/R=0.5∼2.5 for M7.8). The Inadani fault zone (t/R>0.6∼1.6). The central part of Itoigawa-Shizuoka tectonic line (t/R=0.9), which moved about 1200 years ago. The Fujikawa fault zone (t/R>0.9∼1.4). The Kozu. Matsuda-Kannawa fault zone (t/R>1.0∼2.8).