—Western Hokkaido, the northernmost island of Japan, is prone to landsliding due to geologic, geomorphologic and climatic change. From 1985 to 1997, many rapid large-scale landslides occurred in western Hokkaido, several of which are reviewed in this paper. The 1988 Kamaya Slide, the 1991 Tachimachi-misaki Slide (which was preceded by the 1985 Orito Slide), the 1993 Okushiri-Port Slide, and the 1994 Motochi Earthflow are described. Finally, two sea-cliff rockfalls are also described.¶The Okushiri-port Slide and the Toyohama Tunnel Rockfall claimed 29 and 20 lives, respectively. Except for the Okushiri-port Slide, which was induced by Hokkaido Nansei-oki Earthquake, most of the slides and rockfalls were probably related to geological structures, such as gentle-dipping strata interbedded with clayey tuffs and were triggered by long-duration and/or high precipitation, causing increased groundwater levels and/or high water pressures.
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