Characterization of slip zone associated with the 1999 Taiwan Chi-Chi earthquake: X-ray CT image analyses and microstructural observations of the Taiwan Chelungpu fault

To characterize the fault-related rocks within the Chelungpu fault, we performed X-ray computed tomography (CT) image analyses and microstructural observations of Hole B core samples from the Taiwan Chelungpu-fault Drilling Project. We identified the slip zone associated with the 1999 Chi-Chi earthquake, within the black gouge zone in the shallowest major fault zone, by comparison with previous reports. The slip zone was characterized by low CT number, cataclastic (or ultracataclastic) texture, and high possibility to have experienced a mechanically fluidized state. Taking these characteristics and previous reports of frictional heating in the slip zone into consideration, we suggested that thermal pressurization was the most likely dynamic weakening mechanism during the earthquake.     

A preliminary study of D/H ratios of chlorites

Chemistry dependence of D of chlorites is inferred from data for natural chlorites. D of water equilibrated with those chlorites is estimated to be –2–8.     

Interelement relationships and age-related variation of trace element concentrations in liver of striped dolphins (Stenella coeruleoalba) from Japanese coastal waters

Concentrations of 19 trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Hg, and Pb) were determined in the liver of the striped dolphins (Stenella coeruleoalba) collected around Japan during 1977–1982 to examine the sex difference, age dependence, and interrelationships among trace elements. Tissue distribution of trace elements was also investigated in one adult and one fetus specimens. Generally, concentrations of Se, Sr, Ag, Cd, Cs, Ba, Hg, and Pb were higher in the tissues of adult than those of fetus, whereas the opposite trend was observed for Cr and Tl. There were no significant sex differences in the trace element levels in the liver. Significant positive correlations between age (0–26.5 years) and hepatic concentrations were found for Ag, Se, Hg, V, Fe, Pb, and Sr, suggesting their age-dependent accumulation in the liver. In contrast, hepatic concentrations of Mn and Zn decreased with age. Significant positive relationships were observed between Se, and Hg, Ag, V, Fe, and Sr in the liver.     

Improving GPS positioning estimates during extreme weather situations by the help of fine-mesh numerical weather models

Space geodetic applications require to model troposphere delays as good as possible in order to achieve highly accurate positioning estimates. However, these models are not capable to consider complex refractivity fields which are likely to occur during extreme weather situations like typhoons, storms, heavy rain-fall, etc. Thus it has been investigated how positioning results can be improved if information from numerical weather models is taken into account. It will be demonstrated that positioning errors can be significantly reduced by the usage of ray-traced slant delays. Therefore, meso-scale and fine-mesh numerical weather models are utilized and their impact on the positioning results will be measured. The approach has been evaluated during a typhoon passage using global positioning service (GPS) observations of 72 receivers located around Tokyo, proving the usefulness of ray-traced slant delays for positioning applications. Thereby, it is possible reduce virtual station movements as well as improve station height repeatabilities by up to 30% w.r.t. standard processing techniques. Additionally the advantages and caveats of numerical weather models will be discussed and it will be shown how fine-mesh numerical weather models, which are restricted in their spatial extent, have to be handled in order to provide useful corrections.     

Using VLBI fringe-phase information from geodetic experiments for short-period ionospheric studies

The usage of Very Long Baseline Interferometry (VLBI) fringe-phase information in geodetic VLBI is a new field of research, which can be used for the detection of short-period (i.e., several minutes) variations (scintillations) of the ionosphere. This paper presents a method for the extraction of such disturbances and discusses how dispersive influences can be separated from intra-scan delay variations. A proper functional and stochastic model for the separation of the different effects is presented and the algorithms are applied to real measurements. In an example, it is shown that a traveling ionospheric disturbance in Antarctica can be detected very precisely. A possible physical origin and the propagation properties of the disturbance are presented and the results are compared with GPS measurements. The benefit of this method for other applications is also discussed.     

Numerical Investigations of Mean Winds Within Canopies of Regularly Arrayed Cubical Buildings Under Neutral Stability Conditions

Recently, several attempts have been made to model the wind velocity in an urban canopy in order to accurately predict the mixing and transport of momentum, heat, and pollutants within and above the canopy on an urban scale. For this purpose, unverified assumptions made by Macdonald (Boundary-Layer Meteorol 97:25–45, 2000) to develop a model for the profile of the mean wind velocity within an urban canopy have been used. In the present study, in order to provide foundations for improving the urban canopy models, the properties of the spatially-averaged mean quantities used to make these assumptions have been investigated by performing large-eddy simulations (LES) of the airflow around square and staggered arrays of cubical blocks with the following plan area densities: λ _p = 0.05, 0.11, 0.16, 0.20, 0.25, and 0.33. The LES results confirm that the discrepancy between the spatial average of wind velocity and Macdonald’s five-point average of wind velocity can be large in both types of arrays for large λ _p . It is also confirmed that Prandtl’s mixing length varies significantly with height within the canopy, contrary to Macdonald’s assumption for both types of arrays and for both small and large λ _p . On the other hand, in accordance with Macdonald’s assumption, the sectional drag coefficient is found to be almost constant with height except in the case of staggered arrays with high λ _p .     

Trace elements and stable isotope ratios (δC and δN) in fish from deep-waters of the Sulu Sea and the Celebes Sea

Trace elements (TEs) and stable isotope ratios (δ¹⁵N and δ¹³C) were analyzed in fish from deep-water of the Sulu Sea, the Celebes Sea and the Philippine Sea. Concentrations of V and Pb in pelagic fish from the Sulu Sea were higher than those from the Celebes Sea, whereas the opposite trend was observed for δ¹³C. High concentrations of Zn, Cu and Ag were found in non-migrant fish in deep-water, while Rb level was high in fish which migrate up to the epipelagic zone, probably resulting from differences in background levels of these TEs in each water environment or function of adaptation to deep-water by migrant and non-migrant species. Arsenic level in the Sulu Sea fish was positively correlated with δ¹⁵N, indicating biomagnification of arsenic. To our knowledge, this is the first study on relationship between diel vertical migration and TE accumulation in deep-water fish.     

GIS-Based Probabilistic Mapping of Landslide Hazard Using a Three-Dimensional Deterministic Model

Based on a new Geographic Information Systems (GIS) grid-basedthree-dimensional (3-D) deterministic model and taking the slopeunit as the mapping unit, this study maps landslide hazard usingthe 3-D safety factor index and failure probability. Assuming theinitial slip to be the lower part of an ellipsoid, the 3-D critical slipsurface in the 3-D slope stability analysis is located by minimizingthe 3-D safety factor using the Monte Carlo random simulation.The failure probability of the landslide is calculated using anapproximate method in which the distributions of c, andthe 3-D safety factor are assumed to be in normal distribution.The method has been applied to a case study on three-dimensionallyand probabilistically mapping landslide hazard.     

D/H ratios of the coexisting phlogopite and richterite from mica nodules and a peridotite in South African kimberlites

The water content and D/H ratio of pairs of phlogopite and richterite in kimberlite samples were measured. The water contents of both minerals were lower than the formula content. On the basis of D/H ratios of the pair, phlogopite and richterite can not be regarded as a simple equilibrium product with respect to hydrogen isotope exchange. It seems impossible to estimate D/H ratio of the mantle water through D/H ratios of the hydrous silicate pairs.