Microtremor Measurement in the Area of Ube City

Measurement of microtremors in the area of Ube City were carried out in order to investigate the relation between the properties of alluvium and the properties of microtremor. Measurements were made at 79 sites as shown in Fig. 1. The distribution of the predominant period is shown in Fig. 2. The classification of ground is determined by the relation between the predominant period and the longest one. Our conclusions are as follows : (1) The classification of the ground determined by microtremors is shown in Fig. 7. (2) The relation between the predominant period T (sec) and the thickness H (m) of alluvium may be written. T=H/24 (3) The relation between the maximum amplitude A (μ) and the thickness H (m) of alluvium may be written log A=H/(38)-1.886