A global barotropic ocean model driven by synoptic atmospheric disturbances for detecting seafloor vertical displacements from in situ ocean bottom pressure measurements

A global barotropic ocean model forced by atmospheric disturbances is developed for the detection of seafloor vertical displacements from in situ ocean bottom pressure (OBP) data. The model accuracy is validated by deep-sea OBP data at more than 100 sites obtained over the global ocean. Parameters and boundary conditions including the horizontal resolution incorporated in the ocean model are tested in order to accurately simulate the nontidal (>2 days) OBP variations. The horizontal resolution is found to the factor that most significantly affects the simulated result. The finer the horizontal resolution applied, the smaller the model variability is. The model accuracy is highest when the horizontal resolution is 1/12°, but deteriorates when the horizontal resolution is finer than 1/12°. This may indicate a failure of the energy dissipation parameterization in the barotropic ocean model. Using the developed 1/12° model, the root-mean-square of the observed nontidal OBP component can be reduced by 18 % as an average of all the OBP data used. It is found that the 1/12° model is useful for the detection of a slow seafloor vertical displacement of centimeters related to the 2011 Tohoku-Oki earthquake from in situ OBP records near the hypocenter of the earthquake.     

Effects of low pCO2 conditions on sea urchin larval size

Ocean acidification results from an increase in the concentrations of atmospheric carbon dioxide (CO₂) impacts on marine calcifying species, which is predicted to become more pronounced in the future. By the end of this century, atmospheric pCO₂ levels will have doubled relative to the pre‐industrial levels of 280 ppm. However, the effects of pre‐industrial pCO₂ levels on marine organisms remain largely unknown. In this study, we investigated the effects of pre‐industrial pCO₂ conditions on the size of the pluteus larvae of sea urchins, which are known to be vulnerable to ocean acidification. The larval size of Hemicentrotus pulcherrimus significantly increased when reared at pre‐industrial pCO₂ level relative to the present one, and the size of Anthocidaris crassispina larvae decreased as the pCO₂ levels increased from the pre‐industrial level to the near future ones after 3 days' exposure. In this study, it is suggested that echinoid larvae responded to pre‐industrial pCO₂ levels. Ocean acidification may be affecting some sensitive marine calcifiers even at the present pCO₂ level.     

Railway embankment failure due to ballast layer breach caused by inundation flows

A railway embankment constructed on a floodplain is at risk of damage due to flooding flows. The process and critical conditions that lead to railway embankment damage during flooding are not clearly understood, rendering risk estimations impossible and hindering the development of flood-resilient rail systems. For this work, we first reviewed records of railway damage in flood plains and flows through the ballast layer. The breaching process was selected as the focus of our study. We secondly specified the fundamental characteristics of flows through a ballast layer. The critical flow rate per unit width and the minimum upstream water depth required for initiating extensive ballast breaching were experimentally evaluated using a full-scale ballast layer with rails and sleepers constructed using materials originally utilized in actual railways. A two-dimensional flow model was then employed for estimating the flow through a ballast layer that was placed on an impermeable base embankment. A simple ballast breaching model was also employed in order to explore a higher flow rate condition that could not be represented in our experiment due to limited facilities. The breaching pattern represented by the simulation model corresponded to the breaching pattern observed in the experiment. In addition to the above, here, we also discuss the ballast breaching process based on qualitative field records and quantitative experimental results, as well as the ballast breaching process as represented by the simulation.     

Characteristics and Mineralization Age of the Fukusen No. 1 Vein,Hishikari Epithermal Gold Deposits,Southern Kyushu,Japan

The Fukusen No. 1 vein is located in the southeastern part of the Yamada deposit, Hishikari epithermal gold deposits, southern Kyushu, Japan. ⁴⁰Ar/³⁹Ar plateau ages of adularia from the margin and the center of the Fukusen vein are determined to be 0.617 ± 0.024 Ma and 0.606 ± 0.009 Ma, respectively. The Fukusen No. 1 vein shows banding structure composed mainly of quartz, adularia and clay minerals. Colloform texture is displayed by cryptocrystalline to amorphous silica material that is associated with fine-grained electrum and sulfides near the center of the vein. Pyrite in the Fukusen No. 1 vein often shows acicular shape resulting from inversion from marcasite. Near the center of the vein, primary marcasite occurs associated with colloform texture of silica. The Fukusen No.1 vein preserves primary texture and materials which were deposited from the ore-forming hydrothermal solution. The Fukusen No. 1 vein was formed in a short period and is one of the youngest veins in the Hishikari deposits.     

Periodic oscillations found in the velocity field of a quiescent prominence

With the purpose of detecting periodic oscillations or waves in a quiescent prominence, temporal variations of a Ca ii K line profile have been studied. The most conspicuous phenomenon found here is the fact that the edge of the prominence showed, over some 20000 km along the spectrograph-slit, periodic velocity fluctuations of nearly the same phase with periods of 210–240 s and with an amplitude of up to ± 2 kms ^–1. At other portions, several different periods of peaks (160–400 s) can also be seen in the power spectra, but less distinctly. As to the intensity and the line width, however, no periodic variations have been detected.     

Analysis of an elongated narrow coronal streamer observed at the 1973 solar eclipse

A detailed photometric analysis has been made of a narrow elongated coronal streamer observed at the 1973 total eclipse. After deriving real intensity distributions, the electron density has been deduced under the assumption that the distribution is axially symmetric and that the decrease in density from the central axis follows the gaussian law. The results show that the gradient of the electron density is much steeper at the lower part, nearest to the solar limb, than those reported previously for larger scale streamers.On leave from the Observatorio de Huancayo, Instituto Geoflsico del Peru as a trainee of the Japan International Cooperation Agency.     

Experimental and analytical investigation of the response of a mud layer to solitary waves

Ocean Dynamics - Although the different aspects of wave-mud interaction have been studied by many researchers, few studies have been conducted on the effect of solitary wave on the particle...     

Out‐of‐plane stability assessment of buckling‐restrained braces including connections with chevron configuration

One of the key limit states of buckling‐restrained braces (BRBs) is global flexural buckling including the effects of the connections. The authors have previously proposed a unified explicit equation set for controlling the out‐of‐plane stability of BRBs based on bending‐moment transfer capacity at the restrainer ends. The proposed equation set is capable of estimating BRB stability for various connection stiffnesses, including initial out‐of‐plane drift effects. However, it is only valid for symmetrical end conditions, limiting application to the single diagonal configuration. In the chevron configuration, the out‐of‐plane stiffness in the two ends differs because of the rotation of the attached beam. In this study, the equation set is extended to BRBs with asymmetric end conditions, such as the chevron configuration. Cyclic loading tests of the chevron configuration with initial out‐of‐plane drifts are conducted, and the results are compared with the proposed equation set, which is formulated as a function of the normalized stiffness of the attached beam. © 2016 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd. © 2016 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.