Developments in Geotectonics, 3: Island Arcs: Japan and its Environs focuses on geophysical and geological characteristics of island arcs. The book first reviews the geophysical and geological features of island arcs, including topography, crust and upper mantle structure, seismicity, direction of principal stresses of earthquakes, crustal deformation and fault systems, and geological structure. The distributions of Cenozoic volcanoes and hot springs, petrology of volcanic rocks, magnetic fields, and anomaly of electrical conductivity are also discussed. The publication also takes a look at the Cenozoic history of the Japanese Islands relative to the formation of island arcs. The Quaternary tectonic movements of Japan are reviewed. The text ponders on the processes under island arcs, such as generation and ascent of primary magma; convection current descending under island arcs; island arc tectonics and oceanic ridge tectonics; and mechanical process inferred from seismic wave radiation. The text is a valuable reference for geologists and readers interested in island arcs.