Haku-san, along with Fuji-san and On-take, is one of Japan's three most sacred mountains. It is a complex andesitic-dacitic stratovolcano overlooking the Japan Sea. The 2702-m-high Haku-san was constructed over a high basement of sedimentary rocks in a region of very heavy snowfall that has contributed to erosional dissection. Holocene eruptions have consisted of phreatic or phreatomagmatic explosions from several summit craters. Partial collapse of the summit produced a debris avalanche down the east flank during the mid-Holocene. Historical eruptions were recorded over almost a thousand-year period until the 17th century.