5:15 PM - 6:45 PM
[U15-P111] Building Damage Survey Around Strong-Motion Observation Points in the 2024 Noto Peninsula Earthquake and Prototype Development of Damage Database
Keywords:the 2024 Noto Peninsula Earthquake, Damage Estimation, Damage Detection, Building Damage, Damage Survey, GIS
In the Noto Peninsula earthquake, 8,695 houses were completely destroyed as of April 2 (Cabinet Office, 2024), and the number is expected to increase in the future. In order to solve the problem of taking a long time to assess the full extent of damage and to support disaster response, a real-time damage estimation system (J-RISQ) (Fujiwara et. al, 2019) and a damage assessment method using aerial photographs (Naito et. al, 2021) have been developed.
In this study, we conducted a building damage survey to obtain quantitatively verifiable data necessary for the development of such methods, and developed a prototype damage database.
The target of the building damage survey was the area around the strong-motion earthquake observation points and the area where the damage to buildings was estimated to be large by J-RISQ. The survey method was based on Okada and Takai (1999), in which damage was classified into seven levels, from D0 to D6, based on observation of the exterior appearance. Based on the exterior appearance, the building type was classified as "wooden, wood prefabricated, S, RC, or other" and the building age as "old resistance standards(before 1981), new resistance standards (1982-1999), or new resistance standards (after 2000)". The data were input using tablets and converted into GIS data.
At the time of writing, a total of 4,130 buildings in 12 districts have been surveyed. The figure shows the location of each district, the seismic intensity distribution estimated by J-RISQ, and the damage ratios of wooden buildings estimated to be old earthquake-proof, after 1982, and after 2000, respectively, for each district. The ratio of the damage equivalent to total collapse is smaller for non-wooden buildings than for wooden frame buildings, and the damage tends to decrease as the building age becomes older. However, since the structure and age of the building are estimated from the exterior appearance, they need to be carefully examined.
Next, the damage rates of all the surveyed buildings were aggregated by 250 m mesh, and it was confirmed that the mesh with a damage rate of 50% or more equivalent to the total collapse of old earthquake-resistant wooden buildings had an estimated seismic intensity of 5.8 or higher as measured by J-RISQ. We also confirmed that the mesh is composed of lowland topographic features relatively close to coasts and rivers, which are classified as sandbars and gravel bars, fans, gravelly plateaus, hinterland wetlands, deltas and coastal lowlands, and reclaimed land by microtopography classification (Wakamatsu and Matsuoka, 2013).
The mesh with a damage rate of more than 50% equivalent to the total collapse of old earthquake-resistant wooden buildings was distributed in the Ukai, Shoin, and Otani districts of Suzu City, the Kawai-cho and Monzen districts of Wajima City, the Omachi district of Anamizu Town, and the Tazuruhama district of Nanao City, etc. The damage rate was also found to be high in each district. In each area, it was found that damage was concentrated in some areas and not in others.
We plan to continue our research and development for the construction of a damage database and the advancement of real-time damage estimation and situation assessment methods.
Acknowledgments: The seismic intensity estimated by J-RISQ is based on data provided by K-NET, KiK-net, local governments and the Japan Meteorological Agency.
In this study, we conducted a building damage survey to obtain quantitatively verifiable data necessary for the development of such methods, and developed a prototype damage database.
The target of the building damage survey was the area around the strong-motion earthquake observation points and the area where the damage to buildings was estimated to be large by J-RISQ. The survey method was based on Okada and Takai (1999), in which damage was classified into seven levels, from D0 to D6, based on observation of the exterior appearance. Based on the exterior appearance, the building type was classified as "wooden, wood prefabricated, S, RC, or other" and the building age as "old resistance standards(before 1981), new resistance standards (1982-1999), or new resistance standards (after 2000)". The data were input using tablets and converted into GIS data.
At the time of writing, a total of 4,130 buildings in 12 districts have been surveyed. The figure shows the location of each district, the seismic intensity distribution estimated by J-RISQ, and the damage ratios of wooden buildings estimated to be old earthquake-proof, after 1982, and after 2000, respectively, for each district. The ratio of the damage equivalent to total collapse is smaller for non-wooden buildings than for wooden frame buildings, and the damage tends to decrease as the building age becomes older. However, since the structure and age of the building are estimated from the exterior appearance, they need to be carefully examined.
Next, the damage rates of all the surveyed buildings were aggregated by 250 m mesh, and it was confirmed that the mesh with a damage rate of 50% or more equivalent to the total collapse of old earthquake-resistant wooden buildings had an estimated seismic intensity of 5.8 or higher as measured by J-RISQ. We also confirmed that the mesh is composed of lowland topographic features relatively close to coasts and rivers, which are classified as sandbars and gravel bars, fans, gravelly plateaus, hinterland wetlands, deltas and coastal lowlands, and reclaimed land by microtopography classification (Wakamatsu and Matsuoka, 2013).
The mesh with a damage rate of more than 50% equivalent to the total collapse of old earthquake-resistant wooden buildings was distributed in the Ukai, Shoin, and Otani districts of Suzu City, the Kawai-cho and Monzen districts of Wajima City, the Omachi district of Anamizu Town, and the Tazuruhama district of Nanao City, etc. The damage rate was also found to be high in each district. In each area, it was found that damage was concentrated in some areas and not in others.
We plan to continue our research and development for the construction of a damage database and the advancement of real-time damage estimation and situation assessment methods.
Acknowledgments: The seismic intensity estimated by J-RISQ is based on data provided by K-NET, KiK-net, local governments and the Japan Meteorological Agency.