降下火砕堆積物の"層厚-面積"曲線

概要

論文の詳細を見る
"Thickness-isopach area" curves are drawn on the basis of data from 49 recent eruptions and 10 Usu 1977-1978 eruptions. 1) "Thickness-isopatch area" relation of tephras follows the equation (1) ; Y=AX^n, (X=log_<10>(h_<max>/h), Y=log_<10>(S/S_o). S : the area enclosed by isopach of thickness h. S_o : that of maximum thickness h_<max>). 2) Volume of tephra is calculated using the equation (1). 3) S_e (0.1 h_<max> isopach area) or S_e (characteristic area) is more significant than Walker's D (0.01 h_<max> isopach area) as a dispersal index of tephra and either of them relates with A and n as follows : A=log_<10>(S_e/S_o), n=log_<10>(h_<max>/h_e)/log_<10>(S_c/S_o), and h_c×S_c=(h×S)_<max>. 4) Volume percentage of deposits inside S_c is about 35%, and M_d size of deposits on h_c (characteristic thickness) isopach indicates the size index of tephra. 5) S_e (0.1 h_<max> isopach area) is named an equi-distribution area since S_e×h_<max> indicates volume of tephra.
特定非営利活動法人日本火山学会の論文
1981-04-01