Solute distribution in porous rhyolite as evaluated by sequential centrifugation

Pore water in a porous rhyolite, having a porosity of 27% and pore radii ranging from >25 μm to 0.008 μm, was centrifugally extracted stepwise with increasing centrifugal speed to examine the potential variations of the compositions of pore water and their relationships to reaction and transport occurring in the rock. The rock was soaked for from 1 h to 7 days in an aqueous solution prior to centrifugation. To evaluate the effect of adsorption under minimum effect of dissolution, Li⁺ and Br⁻ were added to the solution as tracer ions. As centrifugal speed increased, water was extracted in order of large to small pores and the thickness of residual water film became thinner. The concentrations of ions dissolving from the rock (Na⁺, K⁺, Ca²⁺, etc.) after 7 days of immersion were relatively constant in pores of 1-10 μm radii and exponentially increased by 3-100 fold with decreasing pore radius to 0.1 μm. These ions are dissolved from the rock and transported toward the exterior of the rock by diffusion. The calculation using a reactive-transport equation showed that the observed concentration changes reflect the change in solute distribution profile with pore size. The concentration of Si after 7 days of immersion was approximately constant or slightly decreased with increasing centrifugal speed, which appears to be controlled by the solubility. The concentration of Li⁺ decreased with increasing centrifugal speed after 1 h of immersion but the trend changed after 7 days of reaction. Initial behavior of Li⁺ is explained by adsorption on pore walls, and the change of trend is explained by desorption of that previously adsorbed, slight amounts of dissolution, and inflow from the outside of the rock. The change in concentration of Br⁻ with increasing centrifugal speed was small, probably because Br⁻ was not adsorbed on the surfaces. The sequential centrifugation thus provides information on the solute distribution associated with reaction and transport occurring in rock pores.     

Sound velocities of Na0.4Mg0.6Al1.6Si0.4O4 NAL and CF phases to 73 GPa determined by Brillouin scattering method

The sound velocities of two aluminum-rich phases in the lower mantle, hexagonal new Al-rich phase (NAL) and its corresponding high-pressure polymorph orthorhombic Ca-ferrite-type phase (CF), were determined with the Brillouin scattering method in a pressure range from 9 to 73 GPa at room temperature. Both NAL and CF samples have identical chemical composition of Na_0.4Mg_0.6Al_1.6Si_0.4O₄ (40 % NaAlSiO₄–60 % MgAl₂O₄). Infrared laser annealing in the diamond anvil cell was performed to minimize the stress state of the sample and obtain the high-quality Brillouin spectra. The results show shear modulus at zero pressure G ₀ = 121.960 ± 0.087 GPa and its pressure derivative G’ = 1.961 ± 0.009 for the NAL phase, and G ₀ = 129.653 ± 0.059 GPa and G’ = 2.340 ± 0.004 for the CF phase. The zero-pressure shear velocities of the NAL and CF phases are obtained to be 5.601 ± 0.005 km/sec and 5.741 ± 0.001 km/sec, respectively. We also found that shear velocity increases by 2.5 % upon phase transition from NAL to CF at around 40 GPa.     

Model identification and parameter estimation of elastoplastic constitutive model by data assimilation using the particle filter

Data assimilation, using the particle filter and incorporating the soil‐water coupled finite element method, is applied to identify the yield function of the elastoplastic constitutive model and corresponding parameters based on the sequential measurements of hypothetical soil tests and an actual construction sequence. In the proposed framework of the inverse analysis, the unknowns are both the particular parameter within the exponential contractancy model, n_E, which parameterizes various shapes for the yield function of the competing constitutive models, including the original/the modified Cam‐Clay models and in‐between models and the parameters of the corresponding constitutive model. An appropriate set, consisting of the yield function of the constitutive model and the parameters of the constitutive model, can be simultaneously identified by the particle filter to describe the most suitable soil behavior. To examine the validity of the proposed procedure, hypothetical and actual measurements for the displacements of a soil specimen were obtained for consolidated and undrained tests through a synthetic FEM computation and for consolidated and drained tests, respectively. After examining the applicability of the proposed procedure to these test results, the present paper then focuses on the actual measured data, ie, the settlement behavior including the lateral deformation of the Kobe Airport Island constructed on reclaimed land.     

Uptake and biological effects of synthetic glucocorticoids in common carp (Cyprinus carpio)

Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1 μg L⁻¹ for 21 days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC.     

A new one-dimensional simple energy balance and carbon cycle coupled model for global warming simulation

Global warming and accompanying climate change may be caused by an increase in atmospheric greenhouse gasses generated by anthropogenic activities. In order to supply such a mechanism of global warming with a quantitative underpinning, we need to understand the multifaceted roles of the Earth's energy balance and material cycles. In this study, we propose a new one-dimensional simple Earth system model. The model consists of carbon and energy balance submodels with a north–south zonal structure. The two submodels are coupled by interactive feedback processes such as CO₂ fertilization of net primary production (NPP) and temperature dependencies of NPP, soil respiration, and ocean surface chemistry. The most important characteristics of the model are not only that the model requires a relatively short calculation time for carbon and energy simulation compared with a General Circulation Model (GCM) and an Earth system Model of Intermediate Complexity (EMIC), but also that the model can simulate average latitudinal variations. In order to analyze the response of the Earth system due to increasing greenhouse gasses, several simulations were conducted in one dimension from the years 1750 to 2000. Evaluating terrestrial and oceanic carbon uptake output of the model in the meridional direction through comparison with observations and satellite data, we analyzed the time variation patterns of air temperature in low- and middle-latitude belts. The model successfully reproduced the temporal variation in each latitude belt and the latitudinal distribution pattern of carbon uptake. Therefore, this model could more accurately demonstrate a difference in the latitudinal response of air temperature than existing models. As a result of the model evaluations, we concluded that this new one-dimensional simple Earth system model is a good tool for conducting global warming simulations. From future projections using various emission scenarios, we showed that the spatial distribution of terrestrial carbon uptake may vary greatly, not only among models used for climate change simulations, but also amongst emission scenarios.     

Modification to the crystal structure of chlorite during early stages of its dissolution

Early stage processes of Mg-rich chlorite (clinochlore) dissolution were examined, focusing especially on the structural modification at grain edges during dissolution. Focused ion beam transmission electron microscopy sample preparation was applied to crystals dissolved in a flow-through reaction system at pH 3.0 and 25°C for 31 days. The obtained Si and Mg dissolution rates are −11.49 and −11.14 (logR, mol/(m²/s)), respectively, implying dissolution is non-stoichiometric. TEM-EDX analyses of dissolved samples reveal the development of 20–50-nm thick amorphous zone at an outermost rim with a chemical gradient of Mg, lower towards the solid surface, and Si enrichment in this amorphous zone. Crystalline material is partially interwoven with amorphous one at the interface between the amorphous and crystalline regions. These results indicate that the amorphous zone was produced by selective leaching of cations except for Si. Chlorite dissolution may proceed via the formation and thickening of leached layer as a by-product of release to solution of Si at slightly slower rate than Mg.     

Resistivity mapping using the VLF-MT method around surface fault ruptures of the 1995 Hyogo-ken Nanbu earthquake, Japan

Abstract Distinctive fault ruptures, the Nojima Fault and Ogura Fault, appeared along the northwestern coast of Awaji Island at the time of the 1995 Hyogo-ken Nanbu earthquake (Kobe earthquake). In order to delineate the shallow resistivity structures around the faults just after they formed, Very Low Frequency Magnetotelluric (VLF-MT) surveys were made at five sites along the Nojima Fault and at one site along the Ogura Fault. Fourteen transects were made at the one site on the Ogura Fault, and another transect covers the area between the two faults. Changes in apparent resistivity or phase, or both, commonly occur when crossing the surface location of one of the faults, except for the northern transects at OGR-0 on the Ogura Fault. Apparent resistivity values of less than 100 Ωm were observed for Tertiary and Quaternary sediments and values larger than 200 Ωm for granitic rocks. The resistivity structures are related to the morphological characteristics of the fault ruptures. Remarkably conductive zones (less than 10 Ωm in apparent resistivity and 30–40 m in width) were found where the surface displacement is distinct and prominent along a single fault plane. If remarkably conductive zones were formed at the time of the 1995 Hyogo-ken Nanbu earthquake, the results provide a good constraint on the dimensions of a conductive zone near the surface that was made by one earthquake. Alternatively, if characteristic resistivity structures existed prior to the earthquake, the conductive zone was probably formed by some tens of earthquakes in relatively modern times. In this case, this phenomenon is inferred to be a concentration of fracturing in a narrow zone and is associated with the formation of clay minerals, which enhance rock conductivity.     

Development of a Finite Element Simulator for Crustal Deformation with Large Fault Slipping

--In this paper, a finite element model for simulating long-term crustal deformation with large slipping along fault interface is developed, where a rate- and state-dependent frictional law is introduced to represent the faulting processes and frictional behaviors of fault interface. Moreover, viscous and plastic material properties are used to simulate pressure solution creep and cataclasis, respectively. Throughout the simulations on a structural model of fault-bend folds, the distributions of the stress invariants, equivalent viscous plastic strain, and the traction on the fault interface are investigated. The sequence of deformation mechanisms during movement over a ramp is discussed. It is also found that this kind of frictional model is suitable to represent the rate-dependent behavior of fault slipping due to the movement over a ramp and the tractions on fault interface for treating the low frictional problem of fault-bend folds.     

Regional energetics over the North Pacific,South China Sea and the Indonesian seas during winter

The energy equation was applied to four limited regions to investigate the basic mechanisms through which area-averaged eddy kinetic energy is maintained during the northern winter. The regions selected for this study are as follows: extratropical North Pacific (24.2°N–44.6°N, 130°E–150°W), tropical eastern North Pacific (0°–19.6°N, 170°W–110°W), South China Sea and. Bay of Bengal (0°–19.6°N, 80°E–140°E), and Timor Sea and eastern Indian Ocean (0°–19.6°S, 80°E–140°E). The zonally averaged upper flows over the first region were found to be barotropically stable. In contrast, they were barotropically unstable over the second region; namely, eddy motions over the tropical eastern North Pacific are maintained by receiving energy from zonal flows via barotropic interaction. The third and fourth regions are characterized by the importance of the conversion process between eddy available potential and eddy kinetic energy.Contribution No. 77-5, Department of Meteorology, University of Hawaii, USA.     

A Human Damage Prediction Method for Tsunami Disasters Incorporating Evacuation Activities

This study presents a tsunami human damage prediction method employing numerical calculation and GIS (Geographical Information System) for Usa town, Tosa City, Shikoku Island, Japan. Sometime near the end of the first half of the twenty-first century, a huge earthquake is predicted to occur along the Nankai trough and costal areas facing the Pacific ocean of Shikoku Island. Much damage due to the resultant tsunamis will be caused, therefore, it is necessary to predict the extent of human damage for every town in high-risk areas.The number of tsunami victims was estimated by population in areas of maximum inundation. The number of deaths as a result of tsunami was estimated by a method which employed accumulated death toll of every area in terms of time and space, taking into account consideration of time necessary to begin to seek refuge after an earthquake, tsunami inundation depth on land, flow velocity and evacuation speed. As a result of this study a rapid decrease in death toll by early evacuation was shown quantitatively for the first time.Thus, with the method presented here, it is possible to estimate the extent of tsunami human damage on coastal regions, and may be useful as a tsunami human damage countermeasure.