Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake
Most research on the extraction of earthquake-caused building damage using synthetic aperture radar (SAR) images used building damage certification assessments and the EMS-98-based evaluation as ground truth. However, these methods do not accurately assess the damage characteristics. The buildings i...
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| Format: | Article |
| Language: | English |
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MDPI AG
2023-04-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/8/2181 |
| _version_ | 1797603604864958464 |
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| author | Shinki Cho Haoyi Xiu Masashi Matsuoka |
| author_facet | Shinki Cho Haoyi Xiu Masashi Matsuoka |
| author_sort | Shinki Cho |
| collection | DOAJ |
| description | Most research on the extraction of earthquake-caused building damage using synthetic aperture radar (SAR) images used building damage certification assessments and the EMS-98-based evaluation as ground truth. However, these methods do not accurately assess the damage characteristics. The buildings identified as Major damage in the Japanese damage certification survey contain damage with various characteristics. If Major damage is treated as a single class, the parameters of SAR images will vary greatly, and the relationship between building damage and SAR images would not be properly evaluated. Therefore, it is necessary to divide Major damage buildings into more detailed classes. In this study, the Major damage buildings were newly classified into five damage classes, to correctly evaluate the relationship between building damage characteristics and SAR imagery. The proposed damage classification is based on Japanese damage assessment data and field photographs, and is classified according to the dominant damage characteristics of the building, such as collapse and damage to walls and roofs. We then analyzed the backscattering characteristics of SAR images for each classified damage class. We used ALOS-2 PALSAR-2 images observed before and after the 2016 Kumamoto earthquake in Mashiki Town, where many buildings were damaged by the earthquake. Then, we performed the analysis using two indices, the correlation coefficient <i>R</i> and the coherence differential value <i>γ<sub>dif</sub></i>, and the damage class. The results indicate that the backscattering characteristics of SAR images show different trends in each damage class. The <i>R</i> tended to decrease for large deformations such as collapsed buildings. The <i>γ<sub>dif</sub></i> was likely to be sensitive not only to collapsed buildings but also to damage with relatively small deformation, such as distortion and tilting. In addition, it was suggested that the ground displacement near the earthquake fault affected the coherence values. |
| first_indexed | 2024-03-11T04:34:20Z |
| format | Article |
| id | doaj.art-b63c6bf929f64bf18c2672431437c6dd |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-11T04:34:20Z |
| publishDate | 2023-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-b63c6bf929f64bf18c2672431437c6dd2023-11-17T21:13:11ZengMDPI AGRemote Sensing2072-42922023-04-01158218110.3390/rs15082181Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto EarthquakeShinki Cho0Haoyi Xiu1Masashi Matsuoka2Department of Architecture and Building Engineering, Tokyo Institute of Technology, Yokohama 226-8502, JapanDepartment of Architecture and Building Engineering, Tokyo Institute of Technology, Yokohama 226-8502, JapanDepartment of Architecture and Building Engineering, Tokyo Institute of Technology, Yokohama 226-8502, JapanMost research on the extraction of earthquake-caused building damage using synthetic aperture radar (SAR) images used building damage certification assessments and the EMS-98-based evaluation as ground truth. However, these methods do not accurately assess the damage characteristics. The buildings identified as Major damage in the Japanese damage certification survey contain damage with various characteristics. If Major damage is treated as a single class, the parameters of SAR images will vary greatly, and the relationship between building damage and SAR images would not be properly evaluated. Therefore, it is necessary to divide Major damage buildings into more detailed classes. In this study, the Major damage buildings were newly classified into five damage classes, to correctly evaluate the relationship between building damage characteristics and SAR imagery. The proposed damage classification is based on Japanese damage assessment data and field photographs, and is classified according to the dominant damage characteristics of the building, such as collapse and damage to walls and roofs. We then analyzed the backscattering characteristics of SAR images for each classified damage class. We used ALOS-2 PALSAR-2 images observed before and after the 2016 Kumamoto earthquake in Mashiki Town, where many buildings were damaged by the earthquake. Then, we performed the analysis using two indices, the correlation coefficient <i>R</i> and the coherence differential value <i>γ<sub>dif</sub></i>, and the damage class. The results indicate that the backscattering characteristics of SAR images show different trends in each damage class. The <i>R</i> tended to decrease for large deformations such as collapsed buildings. The <i>γ<sub>dif</sub></i> was likely to be sensitive not only to collapsed buildings but also to damage with relatively small deformation, such as distortion and tilting. In addition, it was suggested that the ground displacement near the earthquake fault affected the coherence values.https://www.mdpi.com/2072-4292/15/8/2181synthetic aperture radarALOS-2PALSAR-2building damage assessmentbackscatter coefficientcoherence |
| spellingShingle | Shinki Cho Haoyi Xiu Masashi Matsuoka Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake Remote Sensing synthetic aperture radar ALOS-2 PALSAR-2 building damage assessment backscatter coefficient coherence |
| title | Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake |
| title_full | Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake |
| title_fullStr | Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake |
| title_full_unstemmed | Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake |
| title_short | Backscattering Characteristics of SAR Images in Damaged Buildings Due to the 2016 Kumamoto Earthquake |
| title_sort | backscattering characteristics of sar images in damaged buildings due to the 2016 kumamoto earthquake |
| topic | synthetic aperture radar ALOS-2 PALSAR-2 building damage assessment backscatter coefficient coherence |
| url | https://www.mdpi.com/2072-4292/15/8/2181 |
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