APPLICABILITY OF MICROTREMOR H/V METHOD FOR KIK-NET STRONG MOTION OBSERVTION SITES AND NOBI PLAIN

摘要

In this research, we examined the applicability of microtremor H/V method by earthquake observation data recorded at the strong earthquake motion observation networks of KiK-net, K-net and Nobi Plain which have been established in Japan in recent years. We observed the microtremors at ground surface of total 221 sites where the S wave velocity of base rock is more than 1500m/s, and compared the microteremor H/V spectrum ratio with that of earthquake data. As the result of examination, the followings were clarified. A clear predominant peak appears at a high rate in microtremor H/V. The microtremor H/V spectrum ratio is very similar not only to that of earthquake record on the ground surface, but also to several spectrum ratios of earthquake motions between surface and bedrock. This implies the microtremor H/V reflects the response characteristics based on the both of horizontal and vertical motions in the surface layer. Then, we tried to propose an engineering method in presuming the horizontal incident wave response characteristics of surface layer by using the relation between microtremor H/V and earthquake observation data.