Relation between Seismic Intensity, Epicentral Distance and Magnitude : Part 3. Empirical Formula for Earthquakes Occurring off the Pacific Coast of Eastern Japan

東日本の太平洋岸沖合の地震に対する震度I(気象庁震度階級),震央距離Δ(km),マグニチュードM(気象庁方式)の標準的関係を表す実験式を287個の地震(M≧6,深さ80km以浅)の東日本の火山前線外側の観測点における震度データを用いて求めた.I－Δの平均回帰直線I＝I200-b(Δ-200)の定数を,次の式でMと結んだものを提出する.I200=1.6M-7.9b=0.029-0.0031M火山前線内側の観測点に対してはこの式は適用できない.An empirical formula representing the relation between seismic intensity I (JMA scale), epicentral distance Δ (km) and magnitude M (JMA) has been obtained for earth- quakes (focal depths 0～80km) occurring off the Pacific coast of eastern Japan, using I-Δ data for 287 earthquakes of 6.0≦M≦8.2 from 1926 through 1985. The formula takes the form I=I200-b(Δ-2OO) where I200 = 1.6M-7.9 and b=0.029-0.0031M The formula is applicable only to seismic intensities observed at stations on the Pacific Ocean side of the volcanic front of eastern Japan