ESR dating of the subsidiary faults in the Yangsan fault system, Korea

The Yangsan fault system is located near heavy industrial complexes and nuc lear power plants in the Korean peninsula. We carried out ESR dating of fau lt rocks from the Wonwonsa and Ihwa faults, two subsidiary faults of the Ya ngsan fault system. ESR ages are divided into three groups in order of decr easing confidence: multiple plateau ESR ages; single plateau ESR ages; and maximum ESR ages. The Wonwonsa fault was reactivated at least 4 times and t he Ihwa fault at least 2 times within the Quaternary period. Long-term cycl ic fault activity of some subsidiary faults of the Yangsan fault system occ urred in the Pleistocene, and suggests the possibility of continued activit y on this fault system. (C) 2000 Elsevier Science Ltd. All rights reserved.