Historical Patterns of Heavy Rainfall Event and Deep-Seated Rapid Landslide Occurrence in Japan: Insight for Effects of Climate Change on Landslide Occurrence

Abstract

To clarify effects of climate change on deep-seated rapid landslide frequency, we compiled about 300 landslides information through a literature search since 1600 and the frequency of heavy rainfall event since 1901 in Japan. In the last 120 years, the deep-seated rapid landslide frequency was relatively large. However, the frequency of deep-seated rapid landslide did not increase monotonically with time. The frequency of deep-seated rapid landslide temporary varied and showed decadal-scale patterns. In the last 120 years, three periods of high frequency of deep-seated rapid landslide were existed. Since 1901, the decadal-scale deep-seated rapid landslide frequency well agreed with the decadal-scale heavy rainfall frequency. Mean annual number of deep-seated rapid landslides in the period of high frequency of heavy rainfall events were around 6–8 times larger than those of the low frequency periods. So, the past temporal change of heavy rainfall event frequency already induced temporal change of deep-seated rapid landslide frequency, suggesting that if in future, the heavy rainfall event frequency will increase due to the climate change, the deep-seated rapid landslide frequency might be larger than that in the past.