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[SCG55-P03] Evaluation of site amplification factors of seismic intensity using J-SHIS subsurface structures
Keywords:site amplification factors, seismic intensity, subsurface structure
The Japan Meteorological Agency provides information of ground motion such as earthquake early warning and interpolated seismic intensity distribution. Needless to say, site amplification factors play an important role in them. Empirical site amplification factors are effective, but the estimations are limited at location sites. The National Institute of Earth science and Disaster prevention (NIED) provides subsurface structures down to seismic basements around Japan through the framework of the Japan Seismic Hazard Information Station (J-SHIS). In this study, we evaluate the site amplification factors for seismic intensities derived from the subsurface structure of J-SHIS.
Site amplification correction using empirical factors would enhance the distance-dependent attenuation of observed seismic amplitudes. When we correct observed seismic intensities of the 2005 NW off Fukuoka earthquake (M7.0) using empirical relationship between Vs30 and correction factors for seismic intensities derived by Midorikawa et al. (2008), the correction improved the fitting of regression expression. We also attempt the correction based on the equation proposed by Kawase and Matsuo (2004), but the residual is larger than that of Midorikawa’s equation. Midorikawa’s equation describes the relationship between Vs30 and engineering bedrock. Hence, we further try to correct the amplification between engineering and seismic bedrocks based on seismic structures provided by J-SHIS, but we could not find any meaningful correlation between the residuals of correction based on Midorikawa’s equation and the amplification characteristics of the structures.
Acknowledgment
We thank the National Institute of Earth science and Disaster prevention for the seismograms recorded by K-NET and KiK-net strong motion observation networks and soil structures of J-SHIS that used in this study.
Site amplification correction using empirical factors would enhance the distance-dependent attenuation of observed seismic amplitudes. When we correct observed seismic intensities of the 2005 NW off Fukuoka earthquake (M7.0) using empirical relationship between Vs30 and correction factors for seismic intensities derived by Midorikawa et al. (2008), the correction improved the fitting of regression expression. We also attempt the correction based on the equation proposed by Kawase and Matsuo (2004), but the residual is larger than that of Midorikawa’s equation. Midorikawa’s equation describes the relationship between Vs30 and engineering bedrock. Hence, we further try to correct the amplification between engineering and seismic bedrocks based on seismic structures provided by J-SHIS, but we could not find any meaningful correlation between the residuals of correction based on Midorikawa’s equation and the amplification characteristics of the structures.
Acknowledgment
We thank the National Institute of Earth science and Disaster prevention for the seismograms recorded by K-NET and KiK-net strong motion observation networks and soil structures of J-SHIS that used in this study.