[S-VC28] International Volcanology

[SVC28-P05] A review of late Pleistocene, recent, and future glaciovolcanism in Japan

*Chris Conway¹、Kyoko Kataoka²、Kenichiro Tani³、Osamu Ishizuka¹、Hajime Taniuchi¹ (1.Geological Survey of Japan, AIST、2.Niigata University、3.National Museum of Nature and Science)

キーワード：stratovolcanoes, volcano-ice interaction, Quaternary

This review deals with two fundamental questions arising from the interaction between volcanism and the cryosphere (i.e., glaciovolcanism) during the late Pleistocene and Holocene in Japan: (1) have the long-term construction histories of volcanoes been affected by snow and ice; and (2) what influence does snow have on eruption processes and hazards at active volcanoes? In order to address these questions, we carried out field surveys at stratovolcanoes in Japan to assess the evidence for glaciovolcanism during the last glacial period (ca. 71–12 ka), and summarized volcano–snow interaction processes for historic eruptions. As a result of this study, several sites of late Pleistocene lava–ice interaction have been tentatively proposed for the first time, and locations where further investigations can be undertaken have been identified. Products of effusive glaciovolcanism (e.g., ice-bounded lava flows) are not prominent for volcanoes in Japan, however, and very few cirques, glacial valleys, or lateral moraines have been recognized in these locations. Most stratovolcanoes in northern Honshu and Hokkaido have (modern) summit elevations lower than 2,000 meters above sea level, which were likely insufficient to host glaciers during the last glacial period in Japan. Interactions between volcanic activity and snow over the last 100 years in Japan have produced explosive eruptions and fatal lahars. Further studies of the dynamics of lava flow and tephra emplacement on snow/ice during eruptions will be beneficial for identifying past glaciovolcanic deposits, and for constraining the rates of snow-melt production that may lead to lahars in the future.