Abstract
We report the results of statistical analysis on excellence of vertical components of earthquake ground motions based on factor analysis in this paper. Two cases of models were analized. The case-1 has three items, that is, magnitude (M), epicentral distance (⊿) and ground specimen, and case-2 has four items, added to epicentral depth (H). The results obtained are as follows. (1) The order of the influence on excellence of vertical component (A_V) of earthquake ground motions versus horizontal ones (A_H) are as follows; (1) soil specimen (G) (2) hypocentral distance (⊿) (3) magnitude (M). But each item cannot rule the excellence of vertical component by itself. (2) The epicentral depth (H) has not enough an influence on ratio of max. vertical acceleration to horizontal one. (3) Calculated ratio of A_V/A_H by method of statistical factor analysis correlated highly to observed one. (4) In this cases the fluctuation of magnitude have no significant effect upon the ratio of A_V to A_H. The softer relatively the soil, the larger the ratio of A_V/A_H becoomes.
