3:30 PM - 4:30 PM
[S07-P-18] Studies on Qs of Kyushu district in Japan
We have reported the variability of Qs in southern part of the Kyushu district, in the previous paper. In that paper, we used seismograms, which are from the M4-5 small-adequate scale earthquakes observed by K-NET and KiK-net operated by the National Research Institute for Earth Science and Disaster Resilience, for evaluating the Qs in those areas. As a result, it showed that the average apparent Qs of the line, connecting the seismic source location to the earthquake catalog of JMA and the observation point, changes significantly, depending on regions (route combination of propagations).
In this paper, we evaluate the Qs for the northern part of Kyushu, as the damping properties, using the twofold spectral ratio method and according the condition we assumed in previous papers. First, the northern part of the Kyushu district was divided into “Region A" and “Region B". In addition, the area in the southwestern part of the Kyushu district was indicated as “Region C". The evaluation of Qs was carried out in an area having a planar spread (Area), and as a propagation route (Line) respectively.
The results show clearly that different Qs are evaluated in Area-case and Line-case at each region, and also, Qs are very similar in “Region A" and “Region C". On the other hand, the Qs model of “Region B" which is very different from other regions agrees to the Qs estimated by Izutani (2000). He assumes the propagation path as just under Mt. Krishima. The Qs in other regions are harmonious with the ones estimated by Uchiyama and Yamamoto (2016).
Our results include only small number of earthquakes and the area to be analyzed, we have to continue the investigation for evaluating attenuation properties to perform the analysis, considering the variability of earthquakes and propagation path. As our future tasks, we plan to develop a method for evaluating complex damping structures in order to improve the accuracy of strong ground motion prediction.
In this paper, we evaluate the Qs for the northern part of Kyushu, as the damping properties, using the twofold spectral ratio method and according the condition we assumed in previous papers. First, the northern part of the Kyushu district was divided into “Region A" and “Region B". In addition, the area in the southwestern part of the Kyushu district was indicated as “Region C". The evaluation of Qs was carried out in an area having a planar spread (Area), and as a propagation route (Line) respectively.
The results show clearly that different Qs are evaluated in Area-case and Line-case at each region, and also, Qs are very similar in “Region A" and “Region C". On the other hand, the Qs model of “Region B" which is very different from other regions agrees to the Qs estimated by Izutani (2000). He assumes the propagation path as just under Mt. Krishima. The Qs in other regions are harmonious with the ones estimated by Uchiyama and Yamamoto (2016).
Our results include only small number of earthquakes and the area to be analyzed, we have to continue the investigation for evaluating attenuation properties to perform the analysis, considering the variability of earthquakes and propagation path. As our future tasks, we plan to develop a method for evaluating complex damping structures in order to improve the accuracy of strong ground motion prediction.