Yasuto Itoh – författare

This publication shows the three-dimensional architecture of the enormous complex depression of the Beppu Bay and its surrounding area located in the central part of the island of Kyushu, which is a part of the arc-trench system along the northwestern Pacific margin, where vigorous tectonic events have been prompted by the convergence of the Philippine Sea Plate since the beginning of the Pliocene. High-resolution subsurface images on multi-channel reflection seismic profiles acquired during recent three decades are integrated in order to delineate the configurations of many active faults and multifaceted evolutionary processes of the volcano-tectonic basin. The book attempts to unravel the causal relationship between transient modes of subduction of the oceanic plate and considerable diversity of basinal morphologies developed upon the convergent margin. The present study also assesses the connectivity of the visualized regional fault systems with the recent seismogenic zones in the island that experienced a devastating earthquake in 2016. Multidisciplinary and quantitative analytical results on the basis of geology and geophysics are contained here, which should be of great interest to the industry technical experts, university staffs and graduate/undergraduate students engaged in geological survey and/or civil engineering. Additionally, it will especially be useful to professionals in the fields of Quaternary geology, neotectonics and active fault research.

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.

Convergent plate margins are sites of Earth’s tectonism and material recycling, and have provided researchers with attractive study subjects. Intensive stress on the margins provokes activities of numerous faults and development of large topographic relief, which inevitably results in regional changes in paleoenvironments. This publication focuses on the east Eurasian margin where longstanding subduction of oceanic plates has enhanced buildup of complicated geologic structures. The authors present the late Cenozoic evolution of an arc-trench system along the northwestern Pacific based on an elaborate geological survey and the latest geophysical information. Detailed petrographic description has revealed episodic and considerable influx of high-P/T metamorphosed clasts from the voluminous forearc-side accretionary complexes to the intra-arc sedimentary basins of southwest Japan. This phenomenon is attributed to active exhumation of metamorphic rocks settled on the subducting slab before the massive uplift of watershed mountainous ranges along the islands. Provenance of the exotic clastic materials has been endorsed by sedimentological studies of the Pleistocene strata overlying the intermontane terranes of the pre-Cenozoic rocks. Three-dimensional architecture of neotectonic deformation was delineated utilizing geophysical measures such as gravity and geomagnetic anomalies and reflection seismic surveys. It has been indicated that the complex upper crustal structure of the arc is an expression of recurrent inversion episodes under strong compressive stress. Quantitative restoration of the deformation processes of the southwestern Japan arc gives us the insight that change in the modes of subduction of the Philippine Sea Plate, which had developed as a marginal sea plate in the western Pacific region through the Cenozoic, is probably responsible for the prevailing and time-progressive mountain-building events around the island arc. It is a well-organized study of mobile belts surrounding the globe, and stands as the highest level of integration of neotectonic models dealing with the evolution of convergent margins.

This publication shows the three-dimensional configuration of the gigantic tectonic sag of the Osaka Bay sedimentary basin on the eastern Eurasian margin based on reflection seismic data never before published. The basin has developed relatively quickly since the dawn of the Quaternary. High-resolution subsurface images on the profiles provide highly valuable information about the architecture of active faults, paleoenvironmental changes, and mass balance on the convergent margin. The book presents an excellent case study of a tectonically controlled basin because morphologies and evolutionary processes of such basins show an enormous diversity, reflecting spatiotemporal variation in tectonic stress. Furthermore, this volume provides insight into the general mechanism of sedimentary basin formation.The quantitative analyses contained here will be thought-provoking for industry experts, academics, and graduate and undergraduate students engaged in geologic survey and civil engineering. The contents will be especially useful to professionals in the fields of Quaternary geology, neotectonics, and active fault research.

This publication shows the three-dimensional configuration of the gigantic tectonic sag of the Osaka Bay sedimentary basin on the eastern Eurasian margin based on reflection seismic data never before published. The basin has developed relatively quickly since the dawn of the Quaternary. High-resolution subsurface images on the profiles provide highly valuable information about the architecture of active faults, paleoenvironmental changes, and mass balance on the convergent margin. The book presents an excellent case study of a tectonically controlled basin because morphologies and evolutionary processes of such basins show an enormous diversity, reflecting spatiotemporal variation in tectonic stress. Furthermore, this volume provides insight into the general mechanism of sedimentary basin formation.

The quantitative analyses contained here will be thought-provoking for industry experts, academics, and graduate and undergraduate students engaged in geologic survey and civil engineering. The contents will be especially useful to professionals in the fields of Quaternary geology, neotectonics, and active fault research.