Abstract We investigated the origin of marine sediments and their transfer by water currents using the spatial distribution patterns of multi-elements in terrestrial and marine areas of Kyushu, western Japan. Quaternary volcanic material covers Cretaceous granitic rock and Jurassic–Paleogene sedimentary rock of an accretionary complex in this region. Cluster analysis based on chemical compositions identified the origin of marine sediments from stream sediments originating from the above lithologies. Pyroclastic-flow deposits associated with caldera formation, particularly that of the Kikai Caldera (7.3 ka), were characterized by low Cr/Ti and La/Yb ratios. In contrast, the La/Yb ratio was very high in sediments derived from granitic rock and sedimentary rock of the accretionary complex. The spatial distributions of low Cr/Ti and La/Yb ratios suggest that marine sediments containing pyroclastic materials, which are found within an 80 km radius of the Kikai Caldera, were distributed on the shelf and transported northeastwards by a branch of the Kuroshio Current. The continuous distribution of the medium Cr/Ti and high La/Yb ratios from the land to the coast, slope and deep basin on the Pacific Ocean side suggests that sediments supplied from the terrestrial area were transferred by gravitational transport from the shelf to the deep basin.

Abstract LavaSIM is a lava -flow simulator to carry out three-dimensional (3D) analysis of solid–liquid two-phase lava flows. Heat transfer between molten lava and solidified crust into the air, water and ground is calculated using radiation equations, so we can simulate not only the lava-flow distribution but also its physical characteristics: for instance, the internal convectional structure. Lava viscosity can be treated as a function of temperature, and is associated with the percentage of crystallization. The stop condition for the lava flow is determined by calculating the minimum spreading thickness, taking into consideration the yield strength. This paper also discusses whether LavaSIM, the deterministic lava-flow simulation, can be applied to basaltic lava flows and allow lava-flow characteristics, such as inundated area, temperature distribution, crust–melt distribution, velocity and pressure field, to be quantitatively evaluated.