Rishiri volcano (利尻山, Rishiri-zan) forms is a small island about 20 kilometers west of the northern tip of Hokkaido. The andesitic stratovolcano last erupted ca. 8500 years ago and is strongly eroded. Erosion has sculptured a sharp-topped summit and steep radial ridges. The latest eruptions of Rishiri volcano was ca. 8-9000 years ago.
Rishiri is part of the Rishiri-Rebun-Sarobetsu National Park. A well-known feature is Rishirifuji Onsen, a thermal spring with indoor and outdoor baths at the southern end of the town of Oshidomari.
Rishiri volcano started erupting less than 200,000 years ago, building a stratovolcano and lava domes. Eruptions from the summit vents ceased about 37,000 years ago and since then, the only activity were sporadic eruptions from flank vents, forming scoria cones and maars along a 15-km-long NW-SE rift zone extending to the SE coast.
These flank eruptions were dominantly basaltic, but occasionally included more silica-rich magma including rhyolite. Large lava flows were erupted in the latest period of activity as well, and form most of the northern and western coast. (Smithsonian / GVP volcano information)
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