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| | Abstract | | Applying the seismic intensities and damage ratio of wooden houses is useful for investigating the source image of historical earthquakes without strong ground motion records. In this study, we propose a method to evaluate a distribution of seismic intensities of historical earthquake by using the H/V spectral ratio of microtremors and apply to the 1891 Nobi earthquake. Here, we evaluate seismic intensities at 43 microtremor-measurement stations in the Nobi Plain and near the surface earthquake faults based on the relationship between seismic intensities and the predominant periods of H/V spectral ratio of microtremors. As a result, we classify the stations with the seismic intensity of 7 into two groups: (1) the stations which have the predominant period between approximately 0.4 sec and 0.8 sec, and (2) those have the predominant period of less than approximately 0.4 sec. Seismic intensities of 7 could be generated by the effect of rupture of a causative fault at the stations with the predominant period of less than 0.4 sec. We also demonstrate that the northern part of the Gifu-Ichinomiya Line ruptured as one of the causative faults during the 1891 Nobi earthquake through the strong ground-motion simulations. |
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