Interactive behavior of soil–pile-superstructure system in transient state to liquefaction by means of large shake table tests

Shaking table tests were conducted by means of a large-scale laminar box with 4 m in length, 2 m in width and 2 m in height in order to investigate behavior of a soil-pile-superstructure system in liquefiable ground. A model two-storey structure, supported by a pile group, was set in a saturated sand deposit, and subjected to a sinusoidal base motion with increasing amplitude. Discussions are focused on the transient behavior until soil liquefaction occurs. Main interests are characteristics of springs used in a sway-rocking model and a multi-freedom lumped mass (MFLM) model that are frequently used in soil–pile interaction analysis. The spring constant in the sway-rocking model is represented by restoring force characteristics at the pile head, and that in the MFLM system is represented by an interaction spring connecting the pile to the free field. The transient state prior to soil liquefaction is shown to be important in the design of a pile because dynamic earth pressure shows peak response in this state. The reduction of the stiffness due to excess porewater generation and strain dependent nonlinear behavior is evaluated.     

Formation and shortening deformation of a back-arc rift basin revealed by deep seismic profiling, central Japan

The northern Fossa Magna (NFM) basin is a Miocene rift system produced in the final stages of the opening of the Sea of Japan. It divides the major structure of Japan into two regions, with north-trending geological structures to the NE of the basin and EW trending structures to the west of the basin. The Itoigawa-Shizuoka Tectonic Line (ISTL) bounds the western part of the northern Fossa Magna and forms an active fault system that displays one of the largest slip rates (4–9 mm/year) in the Japanese islands. Deep seismic reflection and refraction/wide-angle reflection profiling were undertaken in 2002 across the northern part of ISTL in order to delineate structures in the crust, and the deep geometry of the active fault systems. The seismic images are interpreted based on the pattern of reflectors, the surface geology and velocities derived from refraction analysis. The 68-km-long seismic section suggests that the Miocene NFM basin was formed by an east dipping normal fault with a shallow flat segment to 6 km depth and a deeper ramp penetrating to 15 km depth. This low-angle normal fault originated as a comparatively shallow brittle/ductile detachment in a high thermal regime present in the Miocene. The NFM basin was filled by a thick (>6 km) accumulation of sediments. Shortening since the late Neogene is accommodated along NS to NE–SE trending thrust faults that previously accommodated extension and produce fault-related folds on their hanging wall. Based on our balanced geologic cross-section, the total amount of Miocene extension is ca. 42 km and the total amount of late Neogene to Quaternary shortening is ca. 23 km.     

Habitability analyses of aquatic bacteria

Habitability is defined as an ability of an organism to inhabit different environments. Habitability of organisms, however, cannot be inferred from analyses such as a whole genome or community structures. A recently developed database, the MetaMetaDB, gives us information from what kind of environments one particular 16S rRNA sequence data has ever been obtained, and thus enables us to infer the habitability of the bacterium in question. In order to check the applicability of this database to study the habitability of aquatic bacteria, samples collected at two Naka River stations, one estuarine station from Naka River Estuary, two coastal stations at Oarai in Ibaraki Prefecture, Japan and one station in the Kuroshio Current of the western North Pacific were examined. The phylotypes were tracked against the MetaMetaDB and it was reasonably found that the low-salinity stations were dominated by sequences with “freshwater and groundwater”, “human” and “wastewater” habitat identities, while the high-salinity stations were dominated by those with a “marine” identity. The phylotypes of low-salinity stations with a particular habitat identity were absent or rare in the high-salinity stations and vice versa. The MetaMetaDB also showed that sequences of Cyanobacteria or related phylogenetic groups may be present in the human gut, as well as the probable distribution of the relatives (ancestors/descendants/siblings) of some bacteria. These overall findings proved that the MetaMetaDB is useful as a new tool to infer microbial habitability and it gives us new information on the possible origin and ecology of microorganisms in the environments.     

The dependence of precipitation on wind direction over the Kuroshio front in the winter East China Sea

This study investigates atmospheric responses to the directions of surface wind over the Kuroshio front in the East China Sea, using wintertime satellite-derived data sets. Composite maps of sea surface temperature, wind speed, precipitation, turbulent heat flux, surface wind divergence, and the curl of wind vectors above the atmospheric boundary layer are depicted based on the classification of intense northeasterly (along the front) and northwesterly (across the front) winds over the East China Sea. When northeasterly winds prevail, considerable precipitation occurs on the offshore side of the Kuroshio front, in contrast to periods when northwesterly winds prevail. First, the northeasterly winds strengthen above the front because of the downward transfer of momentum from the fast-moving air at higher levels and/or an adjustment of sea level pressure over the oceanic front, although the process by which the influence of the Kuroshio penetrates beyond the marine atmospheric boundary layer remains unclear. Second, a cyclonic vortex forms above the marine atmospheric boundary layer (at 850-hPa height) on the offshore side of the front, and thereafter, surface wind convergence via Ekman suction (hence, enhanced precipitation) occurs over the East China Sea shelf breaks. The northeasterly winds blow over the East China Sea when the Aleutian Low retreats to the east and when high sea level pressure covers the northern Sea of Japan.     

Electrochemical aspects of grinding media-mineral interactions in magnetite ore grinding

Electrochemical aspects of grinding media-mineral interactions in magnetite ore grinding are illustrated from the viewpoint of corrosive wear of grinding balls and changes in the surface properties of the ground minerals. The corrosive wear of mild steel and HCLA steel was found to be small in contact with magnetite, while the combined presence of pyrrhotite and oxygen accelerated the corrosion of the above ball materials. Austenitic stainless steel exhibited passive behavior under all the above conditions. Galvanic coupling of mild steel with magnetite or pyrrhotite resulted in the formation of a surface reaction product consisting of iron hydroxide species on the mineral.     

The difference in chemical composition of the 1962 lava from miyakezima magma reservoir in Japan

Many examples of mixed magmas in banded lavas have been studied. Another type of mixed magmas or inhomogeneity of magma reservoir found in the 1962 lava flows of Miyake-zima Volcano erupted from fissures is reported.     

Whole mantle SH velocity model constrained by waveform inversion based on three-dimensional Born kernels

A whole mantle SH velocity model is obtained by using a unique data set and techniques. Body and surface waveforms including major and multi-orbit phases are used as a data set and are inverted by using 3-D Born kernels. The resultant model, SH18CE, reveals the different natures of the two major upwelling systems: the strong low velocity anomalies beneath Africa extend for more than 1000 km from the core–mantle boundary (CMB), whereas those beneath the Pacific are restricted to 300–400 km from the CMB. The results also show the variable natures of stagnant slabs on the 670 discontinuity around Japan: the depths of the strongest high velocity anomalies within the stagnant slabs are different region by region, which is consistent with the detailed delay time tomography model in this area.