Abstract
Abstract. The Tohoku-Oki earthquake on 11 March 2011 caused significant widespread crustal movements. In a previous study, we proposed a method for capturing two-dimensional (2-D) surface displacements from a pair of pre- and post-event TerraSAR-X (TSX) intensity images. However, it is impossible to detect three-dimensional (3-D) displacements from one pair of TSX images. In this study, three pairs of pre- and post-event TSX images taken on different paths were used to estimate 3-D crustal movements. The relationship between the actual 3-D displacements and the converted 2-D movements in the synthetic-aperture radar (SAR) images was derived based on the observation model of a SAR sensor. The 3-D movements were then calculated from three sets of detected 2-D movements that occurred within a short time period. Compared with GPS observations, the proposed method was found to be capable of detecting the 3-D crustal movements with sub-pixel accuracy.
Highlights
The Mw 9.0 Tohoku-Oki earthquake occurred on 11 March 2011 off the Pacific coast of northeastern (Tohoku) Japan and caused large tsunamis and widespread devastation
According to the GPS observation network system (GEONET) of the Geospatial Information Authority (GSI) in Japan, significant crustal movements were observed over a wide area (Ozawa et al, 2011)
The 3-D crustal movements caused by the 2011 Tohoku-Oki earthquake were estimated from 2-D displacements that were detected from TerraSAR-X intensity image pairs from three different paths
Summary
The Mw 9.0 Tohoku-Oki earthquake occurred on 11 March 2011 off (oki in Japanese) the Pacific coast of northeastern (Tohoku) Japan and caused large tsunamis and widespread devastation. InSAR can detect displacements at the centimetre level despite its metrelevel image (pixel) resolution, but displacements can only be obtained in the slant-range direction. Another drawback of InSAR is that the method is applicable only for relatively small coherent displacements. We have employed an improved pixel-offset method for a descending pair of high-accuracy georeferenced TSX data to estimate the absolute ground displacements (Liu and Yamazaki, 2013). Three pairs of pre- and post-event TSX intensity images for the 2011 Tohoku-Oki earthquake taken in ascending and descending paths were used to detect 2-D crustal movements using the improved pixel-offset method based on the displacements of non-damaged buildings. The accuracy of the 3-D detection results was demonstrated and compared with the results from three GEONET station records
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