Permalink : http://hdl.handle.net/2115/36662

On August 7 (09h 12m, local time), 1977, a major eruption of dacite pumice occurred from the summit of Usu Volcano (42°32'N, 140°50'E), Hokkaido, Japan, after 32 years of dormancy since the birth of Showa-Shinzan lava dome. Four notable explosive eruptions, two moderate and ten small ones have been recorded until the midnight of August 13-14, and then marked crustal movements and local earthquake swarms continue still at present. The sequence of the present eruption, the distribution and nature of the new ejecta, and the topographic deformation of the volcano, are briefly given in this report.