Detection of three-dimensional crustal movements due to the 2011 Tohoku, Japan earthquake from TerraSAR-X intensity images

Abstract

The Tohoku earthquake on March 11, 2011 caused widespread devastation and significant crustal movements. According to the GPS Earth Observation Network System (GEONET) operated by Geospatial System Institution (GSI) of Japan, crustal movements with a maximum of 5.3 m to the horizontal direction (southeast) and a maximum of 1.2 m to the vertical direction (down) were observed over wide areas in the Tohoku (north-western) region of Japan. A method for capturing the two-dimensional (2D) surface movements from pre- and post-event TerraSAR-X (TSX) intensity images has been proposed by the present authors in our previous research. However, it is impossible to detect the threedimensional (3D) actual displacement from one pair of TSX images. Hence, two pairs of pre- and post-event TSX images taken in ascending and descending paths respectively were used to detect 3D crustal movements in this study. First, two sets of 2D movements were detected by the authors’ method. The relationship between the 3D actual displacement and 2D converted movement in SAR images was derived according to the observation model of the TSX sensor. Then the 3D movements were calculated from two sets of detected movements in a short time interval. The method was tested on the TSX images covering the Sendai area. Comparing with the GEONET observation records, the proposed method was found to be able to detect the 3D crustal movement at a sub-pixel level.