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.

     

Origin of sapphirine-bearing garnet-orthopyroxene granulites: possible hydrothermally altered ocean floor

Sapphirine is a metamorphic mineral that forms in the deep crust in rocks with distinctive bulk compositions, in particular high concentrations of Mg and Al. This study investigates a thin, discontinuous layer of sapphirine-bearing garnet-orthopyroxene (SGO) granulite within a Palaeoproterozoic mafic granulite together with metamorphosed mafic and ultramafic rocks, micaceous rocks rich in magnetite and pyrite, and marble. All of these rocks occur within a low-strain zone in the Lewisian complex of South Harris, NW Scotland. Data on mineral compositions and major, trace, and rare earth element (REE) patterns provide evidence for the origin of the precursor of the SGO granulite. The host mafic granulite has a trace element signature and REE pattern comparable with that of E-type MORB. The chemical abundances of Nb, Ta, La, Ce, Nd, Zr, Hf, Ti, and V in the SGO granulite, except for one sample that records total element loss, are similar to those of the host mafic granulite; however, in terms of whole-rock element abundances, the former is relatively enriched in MgO and depleted in CaO, Na₂O, MnO, Sr, and Eu. Elements within the SGO granulite that were apparently unaffected by hydrothermal alteration—V, Y, Zr, and Cr—are within the range of values observed in the host mafic granulite. Sm–Nd whole-rock isotope systematics suggest that both the host mafic granulite and SGO granulite were metamorphosed at 1.9 Ga, and the Nd initial ratio is consistent with a MORB source at that time. There is no significant difference in the Nd values of the two rock types, suggesting that they originally belonged to the same protolith. Chemical trends within a narrow zone between the SGO and host rock granulite suggest that the former was derived from a basaltic precursor of the latter by a process of infiltration metasomatism, comparable with the chemical exchange that takes place when hydrothermal fluids in present-day oceanic crust pass through vents in a “recharge zone.” The geological and chemical relations observed in the South Harris rocks are consistent with the following model: hydrothermally altered oceanic basaltic crust was trapped in an accretionary wedge and subducted, followed by granulite-facies metamorphism in a deep continental environment during arc–continent collision. This is the first report of hydrothermally altered oceanic crust that was converted to sapphirine-bearing granulite deep in the continental crust.     

Dissipative devices for earthquake resistant composite steel structures: bolted versus welded solution

This paper investigates and compares the seismic performance of two types of innovative repairable fuse devices for earthquake resistant composite steel frames through experimental tests and numerical analyses. The fuses are energy dissipating devices consisting of steel plates that can be welded or bolted to the beam web and bottom flange. The numerical analyses performed in this study are based on the results of experimental tests carried out on beam-to-column sub-assemblages equipped with both the types of fuse devices. The main differences in terms of hysteretic behavior and failure modes of the fuses are identified through the experimental campaign. Detailed three-dimensional finite element models of the beam-to-column sub-assemblages are then created to provide a deeper insight into both the response and the effectiveness of the two investigated devices. On the basis of the results of both the experimental tests and numerical analyses, simplified models of different types of fuses are developed in order to study the effects of bolted and welded devices on the seismic response of composite steel frames. The results are then extended to the case of three-dimensional building structures with different number of storeys. The experimental and numerical investigations prove the effectiveness of the fuses and highlight the main differences between the two possible solutions.     

1-D DC Resistivity Modeling and Interpretation in Anisotropic Media Using Particle Swarm Optimization

We examine the one-dimensional direct current method in anisotropic earth formation. We derive an analytic expression of a simple, two-layered anisotropic earth model. Further, we also consider a horizontally layered anisotropic earth response with respect to the digital filter method, which yields a quasi-analytic solution over anisotropic media. These analytic and quasi-analytic solutions are useful tests for numerical codes. A two-dimensional finite difference earth model in anisotropic media is presented in order to generate a synthetic data set for a simple one-dimensional earth. Further, we propose a particle swarm optimization method for estimating the model parameters of a layered anisotropic earth model such as horizontal and vertical resistivities, and thickness. The particle swarm optimization is a naturally inspired meta-heuristic algorithm. The proposed method finds model parameters quite successfully based on synthetic and field data. However, adding 5 % Gaussian noise to the synthetic data increases the ambiguity of the value of the model parameters. For this reason, the results should be controlled by a number of statistical tests. In this study, we use probability density function within 95 % confidence interval, parameter variation of each iteration and frequency distribution of the model parameters to reduce the ambiguity. The result is promising and the proposed method can be used for evaluating one-dimensional direct current data in anisotropic media.     

Blowout mechanism of Alasehir (Turkey) geothermal field and its effects on groundwater chemistry

Anatolia region is one of the most seismically active regions in the world and has a considerably high level of geothermal energy potential. Some of these geothermal resources have been used for power generation and direct heating. Most of the high enthalpy geothermal systems are located in western part of Turkey. Alasehir is the most important geothermal site in western part of Turkey. Many geothermal wells have been drilled in Alasehir Plain to produce the geothermal fluid from the deep reservoir in the last 10 years. A blowout accident happened during a geothermal well drilling operation in Alasehir Plain, and significant amount of geothermal fluid surfaced out along the fault zone in three locations. When drilling string entered the reservoir rock about 1000 m, blowout occurred. As the well head preventer system was closed because of the blowout, high-pressure fluid surfaced out along the fault zone cutting the Neogene formation. In order to understand the geothermal fluid effects on groundwater chemistry, physical and chemical compositions of local cold groundwater were monitored from May 2012 to September 2014 in the study area. The geothermal fluid was found to be of Na–HCO₃ water type, and especially, arsenic and boron concentrations reached levels as high as 3 and 127 mg/L, respectively. The concentrations of arsenic and boron in the geothermal fluid and groundwater exceeded the maximum allowable limits given in the national and international standards for drinking water quality. According to temporally monitored results, geothermal fluid has extremely high mineral content which influenced the quality of groundwater resources of the area where water resource is commonly used for agricultural irrigation.     

Modeling of seawater intrusion in a coastal aquifer of Karaburun Peninsula,western Turkey

Seawater intrusion is a major problem to freshwater resources especially in coastal areas where fresh groundwater is surrounded and could be easily influenced by seawater. This study presents the development of a conceptual and numerical model for the coastal aquifer of Karareis region (Karaburun Peninsula) in the western part of Turkey. The study also presents the interpretation and the analysis of the time series data of groundwater levels recorded by data loggers. The SEAWAT model is used in this study to solve the density-dependent flow field and seawater intrusion in the coastal aquifer that is under excessive pumping particularly during summer months. The model was calibrated using the average values of a 1-year dataset and further verified by the average values of another year. Five potential scenarios were analyzed to understand the effects of pumping and climate change on groundwater levels and the extent of seawater intrusion in the next 10 years. The result of the analysis demonstrated high levels of electrical conductivity and chloride along the coastal part of the study area. As a result of the numerical model, seawater intrusion is simulated to move about 420 m toward the land in the next 10 years under “increased pumping” scenario, while a slight change in water level and TDS concentrations was observed in “climate change” scenario. Results also revealed that a reduction in the pumping rate from Karareis wells will be necessary to protect fresh groundwater from contamination by seawater.     

Earthquake swarms on Mount Erebus, Antarctica

Mount Erebus (3794 m), located on Ross Island in McMurdo Sound, is one of the few active volcanoes in Antartica. A high-sensitivity seismic network has been operated by Japanese and US parties on and around the Volcano since December, 1980. The results of these observations show two kinds of seismic activity on Ross Island: activity concentrated near the summit of Mount Erebus associated with Strombolian eruptions, and micro-earthquake activity spread through Mount Erebus and the surrounding area.Seismicity on Mount Erebus has been quite high, usually exceeding 20 volcanic earthquakes per day. They frequently occur in swarms with daily counts exceeding 100 events.Sixteen earthquake swarms with more than 250 events per day were recorded by the seismic network during the three year period 1982–1984, and three notable earthquake swarms out of the sixteen were recognized, in October, 1982 (named 82-C), March–April, 1984 (84-B) and July, 1984 (84-F).Swarms 84-B and 84-F have a large total number of earthquakes and large Ishimoto-Iida's “m”; hence these two swarms are presumed to constitute on one of the precursor phenomena to the new eruption, which took place on 13 September, 1984, and lasted a few months.     

Essential cellular modules for the proliferation of the primitive cell

Bacteria appeared early in the evolution of cellular life on planet Earth, and therefore the universally essential genes or biological pathways found across bacterial domains may represent fundamental genetic or cellular systems used in early life. The essential genes and the minimal gene set required to support bacterial life have recently been experimentally and computationally identified. It is, however,still hard to estimate the ancient genes present in primitive cells compared to the essential genes in contemporary bacteria, because we do not know how ancestral primitive cells lived and proliferated, and therefore cannot directly evaluate the essentiality of the genes in ancestral primitive cells. The cell wall is normally essential for bacterial proliferation and cellular division of walled bacterial cells is normally highly controlled by the essential FtsZ cell division machinery. But, bacteria are capable of reverting to their cell wall deficient ancestral form, called the "L-form". Unlike "normal" cells, L-forms divide by a simple physical mechanism based on the effects of membrane dynamics, suggesting a mode of primitive proliferation before the appearance of the cell wall. In this review, we summarize the experimental and computational investigations of minimal gene sets and discuss the minimal cellular modules required to support the proliferation of primitive cells, based on L-form proliferation.     

An experimental approach for selection/elimination in stream network generalization using support vector machines

Multi-representation databases (MRDB) are used in several Geographical Information System applications for different purposes. MRDB are mainly obtained through model and cartographic generalizations. The model generalization is essentially achieved with the selection/elimination process in which a decision must be made to include or exclude the object at the target level. In this study, support vector machines (SVM) was, for the first time, used for the selection/elimination process in stream network generalization. Within this context, the attributes to be used as input data in the SVM method were determined and weighted according to the associations determined in a chi-squared independence test. 1:100,000-scale (medium resolution) stream networks were derived from two 1:24,000-scale (high resolution) stream networks with different patterns in the United States Geological Survey National Hydrography Data-sets. The derived stream networks were quite similar to the 1:100,000-scale original stream networks in both qualitative and visual aspects.     

Observations of Tsunami Impact on the Coast of Kerala, India

The tsunami generated by the December 2004 Sumatra-Andaman earthquake had a devastating effect on some parts of Kerala coast, which is a coast located in southwest India. Results of post-tsunami field surveys carried out to understand the changes in coastal morphology and sediment characteristics in the worst affected Kayamkulam region of Kerala coast are documented in this study. Analysis of offshore bathymetric data indicates the shifting of depth contours towards shore, indicating erosion of sediments and deepening of innershelf due to the tsunami. Depth measurement along the backwater (T-S canal) in the hinterland region indicates siltation due to the inundation of the canal.