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[SSS14-20] Measurement and Accuracy Evaluation of Surface Fault Displacements of the 2023 Southeastern Türkiye Earthquake Using Pixel Offset Analysis on Optical Satellite Images
Keywords:Earthquakes, 2023 Southeastern Türkiye Earthquake, Optical satellite images, Active faults
Interferometric Synthetic Aperture Radar (InSAR) analysis using SAR images and pixel offset analysis using either SAR or optical images are the main methods that can map the surface deformation with high resolution. With the recent increase in the number of optical satellites in operation by both public and private sectors, high resolution optical images are becoming increasingly available. Moreover, tools for pixel offset analysis have been developed. These advancements have expanded the applicability of pixel offset analysis using optical images.
Pixel offset analysis is a technique that utilizes two images taken at different times, precisely coregistering them over the entire image area, and then converting the remaining distortions into surface displacement values. This method can detect sub-pixel level displacements, as small as less than 1/10 of the pixel spacing for short-wavelength signals (Van Puymbroeck et al., 2000). So far, this technique has been applied to detect deformation fields associated with, for example, large earthquakes, ice sheet flow, and landslides.
In this study, we applied pixel offset analysis to optical images acquired by the PlanetScope, Sentinel-2, and Landsat satellites to measure the surface fault displacements associated with the 2023 southeastern Türkiye earthquake, focusing on the epicentral area. Clear surface fault offsets were identified in the results obtained from the analyses of the images of all three satellites. The results obtained using the PlanetScope, whose spatial resolution was the highest, showed the best agreement with field measurements (Karabacak et al., 2023).
In the southwestern part of the analyzed region, the obtained fault displacements were systematically larger than those measured in the field, suggesting either the effect of fault thickness or the presence of multiple parallel faults. On the other hand, in the northeastern part of the analyzed region, large surface fault displacements were obtained along a seemingly immature fault segment. This finding is consistent with the interpretation that a strongly locked segment, where a significant slip deficit had accumulated, ruptured and caused a large displacement.
Reference: Hachiro, K., and Y. Fukushima (2024). J. Geod. Soc. Japan, 70, 136-149.
Pixel offset analysis is a technique that utilizes two images taken at different times, precisely coregistering them over the entire image area, and then converting the remaining distortions into surface displacement values. This method can detect sub-pixel level displacements, as small as less than 1/10 of the pixel spacing for short-wavelength signals (Van Puymbroeck et al., 2000). So far, this technique has been applied to detect deformation fields associated with, for example, large earthquakes, ice sheet flow, and landslides.
In this study, we applied pixel offset analysis to optical images acquired by the PlanetScope, Sentinel-2, and Landsat satellites to measure the surface fault displacements associated with the 2023 southeastern Türkiye earthquake, focusing on the epicentral area. Clear surface fault offsets were identified in the results obtained from the analyses of the images of all three satellites. The results obtained using the PlanetScope, whose spatial resolution was the highest, showed the best agreement with field measurements (Karabacak et al., 2023).
In the southwestern part of the analyzed region, the obtained fault displacements were systematically larger than those measured in the field, suggesting either the effect of fault thickness or the presence of multiple parallel faults. On the other hand, in the northeastern part of the analyzed region, large surface fault displacements were obtained along a seemingly immature fault segment. This finding is consistent with the interpretation that a strongly locked segment, where a significant slip deficit had accumulated, ruptured and caused a large displacement.
Reference: Hachiro, K., and Y. Fukushima (2024). J. Geod. Soc. Japan, 70, 136-149.