Structural seismic response analysis based on multiscale approach of computing fault–structure system

Structural safety for earthquake waves emitted from a nearby fault is a major concern. For a large complex structure, it might be desired to estimate its seismic response by analyzing a fault–structure system: a full three‐dimensional model in which a source fault and a target structure are modeled so that fault processes, wave propagation and amplification processes, and resulting dynamic responses of the structure can be computed numerically. To analyze this fault–structure system, this paper proposes an efficient approach based on multiscale analysis, i.e. waves emitted from the source fault are computed in the entire system in the geological length‐scale; then they are refined in a small part of the system that includes the structure, and the seismic response of the structure is accurately computed in the engineering length‐scale. Using a long highway tunnel as an example, this paper examines the validity of the proposed approach. The usefulness and applicability of the proposed approach to estimate the structural seismic responses are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

A nonlinear parametric model based on a power law relationship for predicting the coastal tsunami height

When a subduction-zone earthquake occurs, the tsunami height must be predicted to cope with the damage generated by the tsunami. Therefore, tsunami height prediction methods have been studied using simulation data acquired by large-scale calculations. In this research, we consider the existence of a nonlinear power law relationship between the water pressure gauge data observed by the Dense Oceanfloor Network System for Earthquakes and Tsunamis (DONET) and the coastal tsunami height. Using this relationship, we propose a nonlinear parametric model and conduct a prediction experiment to compare the accuracy of the proposed method with those of previous methods and implement particular improvements to the extrapolation accuracy.

     

Predicting community earthquake preparedness: a cross-cultural comparison of Japan and New Zealand

This paper reports on a study investigating cross-cultural equivalence in predictors of earthquake preparedness. Data were collected from Napier (New Zealand) and Kyoto (Japan). These locations were selected because they face comparable levels of seismic risk but differ with respect to their cultural characteristics. This mix of hazard similarity and cultural differences provided an opportunity to assess the degree of cross-cultural equivalence in predictors of earthquake preparedness. Cross-cultural equivalence was examined by assessing the degree to which individual hazard beliefs (outcome expectancies) and social characteristics (community participation, collective efficacy, empowerment, trust) could explain levels of hazard preparedness in each location. Structural equation modelling analyses revealed similarity in the pattern of relationships between predictor variables and intention prepare in the Napier and Kyoto data. It is argued that this provides support for the existence of some universal, cross-cultural equivalence in how hazard beliefs and social characteristics interact to predict the degree to which people adopt earthquake preparedness measures. Differences between the data sets are discussed in the context of the fundamental cultural differences between Japan and New Zealand. The theoretical and practical implications of the findings are discussed.     

Tributyltin in blood of marine fish collected from a coastal area of northern Kyushu, Japan

We investigated levels of the pollutant tributyltin (TBT) in blood of pufferfishes (six species), Japanese sea perch, red sea bream, Japanese common goby, Japanese flounder, rockfish, conger eel, and sea mullet collected off the coast of northern Kyushu, Japan. We found considerable levels of TBT (1.4-190 ng/mL) accumulated in the blood of these fish. Blood TBT concentrations were 1.3-22.5 times liver concentrations and 4.9-78 times muscle concentrations, except in conger eel and mullet. We detected TBT (16-111 ng/mL-blood) in the plasma of the fine-patterned puffer (Takifugupoecilonotus) year-round, without any apparent seasonal trend. These results suggest that fish inhabiting coastal areas of Kyushu, Japan, continue to be contaminated with TBT.     

Hydration-dehydration interactions between glycine and anhydrous salts: Implications for a chemical evolution of life

Polymerizations of organic monomers including amino acids, nucleotides and monosaccharides are essential processes for chemical evolution of life. Since these reactions proceed with “dehydration” reactions, they are possibly promoted if combined with thermodynamically favorable “hydration” reactions of minerals and salts. To test the possibility, we conducted heating experiments of the simplest amino acid “glycine (Gly)” mixed with four simple anhydrous salts (MgSO₄, SrCl₂, BaCl₂ and Li₂SO₄) at 140 °C up to 20 days. Gly polymerization was strongly promoted by mixing with the salts in the order of MgSO₄ > SrCl₂ > BaCl₂ > Li₂SO₄. Up to 6-mer of Gly polymers were synthesized in the Gly-MgSO₄ mixture, and a total yield of Gly polymers attained about 7% of the initial amount of Gly by the 20 days heating. The total yield was about 200 times larger than that from the heating of Gly alone. XRD measurements of the Gly-MgSO₄ mixture revealed the generation of MgSO₄ monohydrate during Gly polymerization. These observations indicate that Gly polymerization was promoted by the salt hydrations through the hydration-dehydration interactions. Based on the observations, we tried to find a relationship between thermodynamic characteristics of the interactions and the promotion effects of each salt on Gly polymerization. It was found that the salts having lower hydration Δ_rG⁰ (easier to hydrate) promote Gly polymerization more strongly. The relationship was used to estimate promotion effects of simple oxide minerals on Gly polymerization. The estimations were consistent with previous observations about the effects of these minerals on Gly polymerization. The fact suggests that the hydration-dehydration interactions between amino acids and minerals are an important mechanism for amino acids’ polymerizations on minerals.     

日本南海弧前西端之下俯冲的九州—帕劳海岭的地震构造意义

作为菲律宾海板块残余岛弧的九州—帕劳海岭正沿着日本南海海槽的最西端俯冲于欧亚板块之下。沿走向布设的地震反射剖面显示出沿弧前增生楔前缘俯冲的九州—帕劳海岭70km宽的构造影像。地磁异常特征、海底地形特征、广角折射数据和陆地地貌证据等使得我们能够将俯冲海岭在弧前的延伸段一直追踪至九州岛的东部。正在俯冲的九州—帕劳海岭携带有大量冗余物质,可能具有相对较大浮力,因此在深部俯冲时与上覆板块的碰撞具有较大的抗性。有鉴于此,我们推测在俯冲海岭和上覆板块基底的接触区之间存在局部大应力构造。此局部大应力区人们已标出有历史冲断层型中等级别地震(6~7级)。当九州—帕劳海岭俯冲至深部时,漂浮的俯冲海岭其两侧的翼部更容易被撕裂而形成板块破裂。我们认为,俯冲的九州—帕劳海岭在深部不仅起到地震凹凸体的作用,而且产生板块破裂作为地震障碍体抑制邻近的日向段巨大逆冲地震的破裂传播。     

Cold air formation and advection over Eurasia during “dzud” cold disaster winters in Mongolia

Large negative temperature anomalies due to cold air advection have been observed over the Eurasian continent in recent years. During the 2009/2010 winter, a large amount of snow accumulated across Central Asia and China, which along with a strong cold air outbreak, resulted in extremely high livestock mortality in Mongolia. The present study examined the surface inversion development over the Eurasian continent in terms of the cold air advection, accumulation, and breaking processes at ground level. Meteorological analyses shown trends toward earlier onsets of snow and subsequent cold air advection from the Arctic through western Siberia during the last decade, which is a possible driver of the persistent enhanced surface cooling observed in mid-winter in Mongolia. Cyclones are shown to be drivers of early snowfall onset at the beginning of winter and the subsequent migration of cold air from the Arctic, and are thus the key to understanding and predicting the frequency and intensity of persistent surface cooling, which is a substantial physical precursor for the cold disaster in Mongolia “dzud.”     

Long-term (36-year) observations on the dynamics of the fish-killing raphidophyte Chattonella in Harima-Nada,eastern Seto Inland Sea,Japan

Long-term changes of the fish-killing raphidophyte Chattonella spp. (Chattonella antiqua, Chattonella marina and Chattonella ovata) were examined in relation to environmental factors at 19 sampling stations in Harima-Nada, eastern Seto Inland Sea, Japan, for 36 years from 1973 to 2008. Long-term trends in the dynamics of Chattonella populations were considered to relate to environmental factors such as nutrient concentrations and water temperature. High nutrient levels during the period from the 1970s to the early 1980s have contributed to the high cell density and large-scale red tides of Chattonella spp. in Harima-Nada. However, nutrient levels exhibited a decreasing trend thereafter, and it is thought that Chattonella spp. cannot form large-scale blooms under the present conditions. After the mid-1990s, the occurrence period of vegetative cells of Chattonella spp. has been several weeks or 1 month earlier than that of the 1970s and early 1980s, and the appearance frequency of Chattonella spp. has increased in the northern coastal area, although the cell density and the spatial scale of the distribution have become lower and smaller than those in the previous decades. It is suggested that the timing of germination of Chattonella cysts has become earlier as a result of the increase in water temperature, and the chances of vegetative growth have also increased, especially at the northern coast where most of large rivers discharge into the Harima-Nada. In addition, the present results revealed that fewer diatoms were also one of the significant factors for the high abundance of Chattonella spp. in Harima-Nada.     

Electrical conduction and polarization of calcite single crystals

The electrical conductivity and polarization properties of calcite single crystals with three orientations, namely, a (00.1) plane perpendicular to the crystallographic c axis (10.0) plane parallel to the crystallographic c axis, and a (10.4) cleavage plane, were studied by both complex impedance and thermally stimulated depolarization current (TSDC) measurements. Conductivities for (00.1)-, (10.0)-, and (10.4)-oriented single calcite crystals at 400–600?°C were 1.16?×?10^?7?–?1.05?×?10^?5, 7.40?×?10^?8?–?4.27?×?10^?6, and 4.27?×?10^?7?–?2.86?×?10^?5 Ω^?1 m^?1, respectively, and the activation energies for conduction were 112, 103, and 101?kJ?mol^?1, respectively. The TSDC spectra verified the electrical polarizability of calcite crystals. The activation energy for depolarization, estimated from TSDC spectra, of the (00.1)-, (10.0)-, and (10.4)-oriented calcite substrates were 112, 119, and 114?kJ?mol^?1, respectively. Considering the correlation between the processes of conduction and electric polarization, we proposed the mechanisms of conduction and polarization in calcite on the assumption of oxide ion transport.