11:00 AM - 1:00 PM
[STT39-P03] The effects of the angle between the building and range direction to the coherence of ALOS-2/PALSAR-2 for the Kumamoto earthquake
Keywords:Building damage, Coherence, PALSAR-2, Left-looking
In recent years, huge earthquakes have been predicted to be occurred in future, and disaster prevention and mitigation have been a focus of attention. Satellite remote sensing, which can observe a wide area during a huge earthquake, is effective in assessing the damage. The ALOS-2/PALSAR-2, is also expected to be utilized in such a situation. We have evaluated the relationship between the coherence before and after the Kumamoto earthquake and the building collapse rate in previous studies. The results showed that a significant correlation was not found between them for ascending(As), but for descending(Ds) orbit. This could be due to the difference of the angle between the buildings and the range direction, and we revealed that the larger the angle, the higher the coherence. We used both Ds and As data with right-looking in previous studies, and more case studies are necessary. Therefore, the purpose of this study is to evaluate the relationship between the coherence and the angle between the building and range direction using data with left-looking of Ds orbit.
The Kumamoto earthquake occurred on April 14, 2016, and this earthquake caused outstanding building collapses especially in Mashiki-town in Kumamoto prefecture. Therefore, the study area of this study was Mashiki-town, and a 200-meter mesh square was produced inside the area for the analysis. The data used in this study was PALSAR-2 acquired on April 20, 2016 and January 14, 2015.
The analysis was divided into two parts; 1) analysis of the relationship between the coherence and the building collapse rate, and 2) analysis of the relationship between the coherence and the angle between the building and range direction. The results showed that the coherence images had no significant difference in the spatial distribution between the right- and left- looking. In addition, the correlation coefficients between the coherence values of each mesh and the collapse rate were -0.62 for left-looking, similar tendency with right-looking. However, the coherence values were about approximately 0.05 lower than those of righ-looking for the whole. It was caused by the difference of the angle between the building and the range direction; that is the percentage of the angle with 45°to 60°for left-looking was 70%, higher than right-looking. This implied that the difference in the angle affected the building damage analysis using the coherence values. In future study, we conduct the quantitative analysis focused on each building.
The Kumamoto earthquake occurred on April 14, 2016, and this earthquake caused outstanding building collapses especially in Mashiki-town in Kumamoto prefecture. Therefore, the study area of this study was Mashiki-town, and a 200-meter mesh square was produced inside the area for the analysis. The data used in this study was PALSAR-2 acquired on April 20, 2016 and January 14, 2015.
The analysis was divided into two parts; 1) analysis of the relationship between the coherence and the building collapse rate, and 2) analysis of the relationship between the coherence and the angle between the building and range direction. The results showed that the coherence images had no significant difference in the spatial distribution between the right- and left- looking. In addition, the correlation coefficients between the coherence values of each mesh and the collapse rate were -0.62 for left-looking, similar tendency with right-looking. However, the coherence values were about approximately 0.05 lower than those of righ-looking for the whole. It was caused by the difference of the angle between the building and the range direction; that is the percentage of the angle with 45°to 60°for left-looking was 70%, higher than right-looking. This implied that the difference in the angle affected the building damage analysis using the coherence values. In future study, we conduct the quantitative analysis focused on each building.