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The 1983 Nihonkai-Chubu Earthquake (M7.7) marked its 40th anniversary in 2023. In Akita City, this earthquake caused three fatalities and damage to residential buildings, including 35 completely destroyed houses and 235 partially damaged houses. Akita City has also experienced earthquake damage from several past events, including the 1896 Rikuu Earthquake, the 1914 Akita Senboku Earthquake, and the 1964 Niigata Earthquake. This study focuses on the damage in Akita City caused by these four earthquakes. The characteristics and spatial distribution of the damage are compiled and examined, and the damage distribution is compared with historical topographic maps from the corresponding periods. Through this analysis, the historical record of earthquake damage in Akita City is outlined. Records of past earthquake damage and their spatial distribution constitute essential baseline data for urban disaster mitigation planning. Based on these results, the relationship between the historical earthquake damage record and the process of urban development in Akita City is discussed.
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Fault displacements can cause structural damage and loss of functionality. The conventional framework for probabilistic fault displacement hazard analysis (PFDHA) estimates the characteristics of distributed ruptures as a function of distance from the principal fault. Recently, revised fault displacement prediction equations (FDPEs) have been proposed as a means to capture the attenuation characteristics of fault displacement in the far-field as a function of distance from the subsurface earthquake source faults, without classifying surface ruptures as principal or distributed. These FDPEs enable us to address many of the challenges identified during the first practical application of PFDHA in Japan, which was conducted at the Ikata site in northwestern Shikoku. In this study, we conducted a case study of PFDHA based on distance from the earthquake source faults at the Ikata site. Based on the results, we report the characteristics of the new FDPEs and insights gained from their practical application at the Ikata site.
