5:15 PM - 6:30 PM
[MIS34-P79] Site amplification at strong-motion stations in the Kumamoto prefecture and identification of underground velocity structures at Mashiki
Keywords:site amplification, microtremor H/V spectral ratio, underground velocity structures
We attempt to identify the underground velocity structures in the deep layer at KMMH16 station from the microtremor H/V spectral ratio of surface waves based on the diffuse field approach (DFA). The initial underground velocity model in the deep layer is referred to the J-SHIS. We obtain the best underground velocity structures after confirming the good coincidence between the theoretical and observed H/V spectral ratios. The identified underground velocity structures are used to evaluate the transfer functions at KMMH16. We make a comparison of the transfer functions at these three KiK-net stations. We find that the site amplification as large as about 8 at 0.2 sec and 1.0 sec is almost the same at the KMMH03 and KMMH14 stations. The site amplification at the KMMH16 station is as large as 10 from 0.2 sec to 1.0 sec, and as large as 5 from 2.0 sec to 3.0 sec which is affected by the deep layers.