Tree-ring response to the 1995 M_w 7.2 Kobe earthquake, southwest Japan

Abstract. The 1995 M_w 7.2 Kobe earthquake produced an ~ 18 km-long surface rupture zone with a maximum right-lateral displacement of ~ 1.8 m along the pre-existing active Nojima Fault in southwest Japan. Field investigations showed that the co-seismic surface ruptures caused severe damage to trees, some of which survived the disaster during the past twenty years along the co-seismic fault scarp. Analysis of tree-rings from the trunk of a 46-year-old Beech tree (Fagus crenata Blume) revealed that the tree was cracked by earthquake-induced damage and that the tree-rings grown during the five-year period after the 1995 earthquake become sharply narrower in width compared to those grown before the earthquake. Our findings indicate that the earthquake damaged trees along the co-seismic fault scarp and hindered the growth of tree-rings by severing the roots. Thus, the results support the idea that older trees growing along or around fault zones can be used for identifying seismic fault events and for dendrochronological studies related to geomorphological processes.