Accurate Sensing of Active Movements of the Land Surface: Basic Theory of Satellite SAR Interferometry and Its Application in a Mobile Belt

This publication introduces the latest achievements of remote sensing technology to the readers, emphasis of which is exclusively on the analyses of the data acquired using synthetic aperture radar (SAR). Because of the outstanding resolution and versatility, man-made satellites equipped with SAR are regarded as a centerpiece of remote sensing of the Earth. The device is quite useful for the study of the evolution of mobile belts that are often highly inaccessible and characterized by intensive and complicated crustal deformation originating from active tectonics. The authors focus on the southwestern Japan arc, a part of the arc-trench system along the northwestern Pacific margin. It is located along the boundaries of four plates and characterized by a large diversity of tectonic types. After comprehensive review of neotectonic context around the island arc, theoretical basis of satellite SAR interferometry is fully described in the order of principles of radar interferometry to common processing chains. Subtle vertical deformations isolated through the analytical sequence, by which we reduce the phase noise and improve the coherence of an interferogram, are carefully examined from the viewpoint of time-progressiveness of recent movements. Five years of data obtained from a spaceborne radar were utilized to produce interferograms for the study area in southwest Japan, which have confirmed significant and cumulative uplift at three locations during the period of observation. Our detailed research has established a causal relationship between the instantaneous surface motion and the longstanding and deep-rooted structural buildup. In the final chapter of the book, a methodological review has demonstrated the great importance of an integrated investigation on the data of SAR differential interferometry in association with various geological and geophysical measures such as conventional modeling of gravity and geomagnetic anomalies, semi-automatic interpretation methods using gravity gradient tensors, regional stratigraphic studies of boreholes linked to seismic surveys, paleomagnetic studies evaluating long-term accumulation of shear strain, and quantitative approaches based on numerical modeling algorithms. The authors' ultimate goal is to clarify the accumulation processes of dynamic deformations of the Earth's crust.