Poster

[DM-P-07] Examination of the S-wave velocity structures by the autocorrelation function using the strong motion records in the Ishikari Plain

*Naofumi Nakagawa¹, Nobuo Takai¹, Michiko Shigefuji² (1. Hokkaido Univ. (Japan), 2. Kyushu Univ. (Japan))

We applied the autocorrelation function analysis to strong motion records observed at several stations in the Ishikari Plain, Hokkaido, Japan. Recently, by applying autocorrelation function (ACF) analysis to strong motion records, the depth of the seismic basement has been investigated, and the S-wave velocity (Vs) structure has been estimating compared with the stacked ACF. Ishikari Plain has sedimentary layers with a thickness of several kilometers, which increases the amplitude and duration of seismic input motion to the plain. During the 2018 Hokkaido Eastern Iburi Earthquake, the seismic intensity of 5- of JMA intensity scale was observed in Sapporo City located on the plain. This earthquake caused liquefaction and several damages to buildings. Sapporo City, which is the capital city in Hokkaido, has a lot of skyscrapers, as well as small and medium-sized buildings. It is important to evaluate an appropriate Vs structure to evaluate an appropriate building design input motion that contributes to mitigating building damage. There are some Vs structures which were constructed with the microtremor exploration and reflection exploration. It is also important to investigate the Vs structure using strong motion records. In this study, we apply the ACF method to strong-motion data in the Ishikari Plain. The observed ACFs are stacked by the Phase-weighted stacking (PWS), which has the effect of further reducing the noise. We compare observed these ACFs and theoretical ones from existing Vs structures at each observation station.