The hydrography,evolution, and hydrological regime of the mouth area of the Shatt al-Arab River

The hydrography, evolution, landscapes, and hydrological regime of the mouth area of the Shatt al-Arab River—the terminal part of the channel system of the Euphrates and Tigris rivers—are considered. The effect of natural and anthropogenic changes in the Euphrates and Tigris regime and the regime of the Persian Gulf of the Indian Ocean is evaluated.     

Variations in the amplitude and phase of VLF radiowaves in the ionosphere during the August 1, 2008, solar eclipse

Time variations in the amplitude and phase of signals of the Russian telecommunication station (the frequency is 25 kHz) on the Arkhangelsk—Kharkov path with a length of about 1600 km on the day of the August 1, 2008 solar eclipse (SE) and on the adjacent days are analyzed. Two types of effects are detected. An increase of the signal amplitude by approximately 32% in comparison with the background days and the 2.1 μs time shift of the signal during 2—2.5 h is referred to the first type. Changes in the spectral composition of the quasiperiodic disturbances in the ionosphere presented the second type of the effects. For spectral analysis of the quasiperiodic variations in the amplitude and phase of the radio signal, the window Fourier transform, adaptive Fourier transform, and wavelet transformation were applied simultaneously. In the period of SE and after it, oscillations with periods of 10—15 min (according to the amplitude data) and also about 10 and 18 min (according to the phase data) were intensified. Based on radio signal characteristics, the parameters of ionospheric disturbances are estimated.     

Hydrochemical aspects of the negro river,patagonia, argentina

Water samples collected in the Negro River drainage basin (Patagonia, Argentina) during two different field trips—the first in May 1972 and the second in January 1973—were analysed for the major dissolved inorganic constituents. Q-mode factor analyses demonstrate that two factors account for over 98 per cent of the variance in both sample suites. They represent: a) the direct influence of solution of evaporites and associated carbonate rocks in an arid environment-type; b) the influence of the weathering products of metamorphic, igneous rocks, and varied non-calcareous sediments. R-mode factor analyses of the two sets of data suggest that although the main mechanisms controlling water chemistry were essentially the same, the principal sources of dissolved solids differed significantly in each separate occasion. Further, the major mechanisms controlling its water chemistry are within a wide spectrum of the so-called ‘rock dominance’.     

The geology of the Vulsinian area,Lazio, Italy

The Vulsinian volcanic area in central Italy is made up of several volcanic complexes: the older east part of the area, with the large volcano-tectonic depression — in our opinion not simply a caldera — of the « Lago di Bolsena », and the younger Latera volcano are the major features. With the aid of field studies, paleomagnetic measurements, absolute age determinations and petrologic data, a scheme of the volcanic evolution has been drawn up, dividing the volcanic activity into six stages. Volcanicity started about 0.92 M.y. ago and lasted until subrecent. Three rock series are distinguished: a trachytic-phonolitic magma, mainly found as ash flows, a potassic mafic magma with its salic derivatives. mainly as lavas, scoria and pyroclastics, and a trachybasaltic rockseries, mainly found as lavas and scoria.     

桑干河阳原—涿鹿段地貌演化

桑干河发源于山西宁武县, 向NE方向流经大同—阳原盆地和王家湾山地流入怀涿盆地。 桑干河阳原—涿鹿段河流阶地发育较好, 对其阶地的研究有助于更好地理解桑干河的演化及其流经区域的构造活动特征。 而桑干河阳原—涿鹿段地貌演化对了解阳原古湖和怀涿古湖的演变有重要意义。 本文通过遥感影像解译及对高分辨率DEM数据分析, 结合实地测量, 综合研究了阳原—涿鹿段桑干河阶地的发育特征。 结果表明, 该区的构造活动强烈, 经历了断块差异性升降运动; 受差异运动的影响, 该段桑干河经历了被分为东西两支河流, 最终又重新贯通的演化过程。     

Toxic Cyanobacteria in Greek Freshwaters, 1987—2000: Occurrence,Toxicity, and Impacts in the Mediterranean Region

In a survey in Greece from 1987 to 2000 hepatotoxic cyanobacterial blooms were observed in 9 out of 33 freshwaters. Microcystins (MCYSTs) were detected by HPLC in 7 of these lakes, and the total MCYST concentration per scum dry weight ranged from 50.3 to 1638 ± 464 μg g^—1. Cyanobacterial genera (Microcystis, Anabaena, Anabaenopsis, Aphanizomenon, Cylindrospermopsis) with known toxin producing taxa were present in 31 freshwaters. From our data and a review of the literature, it would appear that Mediterranean countries are more likely 1) to have toxic cyanobacterial blooms consisting of Microcystis spp. and 2) to have higher intracellular MCYST concentrations. A case study in Lake Kastoria is used to highlight seasonal patterns of cyanobacterial and MCYST‐LR occurrence and to assess cyanotoxin risk. Cyanobacterial biovolume was high (> 11 μL L^—1) throughout the year and was in excess of Guidance Level 2 (10 μL L^—1) proposed by WHO for recreational waters and Alert Level 2 for drinking water. Further, surface water samples from April to November exceeded Guidance Level 3, with the potential for acute cyanobacterial poisoning. Intracellular MCYST‐LR concentrations (max 3186 μg L^—1) exceeded the WHO guideline for drinking water (1 μg L^—1) from September to November with a high risk of adverse health effects. Preliminary evidence indicates that in 3 lakes microcystins are accumulated in some aquatic organisms. Generally, a high risk level can be deduced from the data for the Mediterranean region.     

Traces of the Strong Devastating Earthquakes in the Hansaray and Its Vicinity,Bakhchysarai, Crimea

Izvestiya, Physics of the Solid Earth - Abstract—We study an ancient earthquake that significantly damaged the Hansaray (Khansarai) in Bakhchysarai, Crimea, at the end of the 17th century....     

2012年4月11日苏门答腊8.6级地震前后川滇地区波速变化研究

利用2012年1~6月川滇地区(21°～34°N, 97°～108°E)99个测震数字地震台的连续波形资料, 采用背景噪声层析成像方法反演了2012年4月11日苏门答腊8.6级地震前后川滇地区的波速变化, 同时研究了该地震前后川滇地区地震活动的变化特征。 结果表明, 川滇地区波速结构呈现龙门山断裂带南段至元谋—绿汁江断裂带和安宁河断裂带波速降低而两侧波速升高的特点。 同时, 波速变化与地震活动性变化具有明显的相关性: 在宁蒗—木里和乐山—雅安一带波速增高显著, 地震活动速率也增加; 在龙门山断裂带南段至安宁河断裂带上则表现为明显的波速降低, 而安宁河断裂带也是地震活动速率降低区域。 这表明本研究得到的波速变化的结果有一定的可信度, 也为背景噪声方法应用到地震预测提供了一种可能的途径。     

The emplacement of acid magma in the epizone,and the relationship with ignimbrites,in North Queensland,Australia

There is an aggregate outcrop of 12,000 square miles of Permian-Triassic acid igneous rocks inland from Cairns and Townsville, North Queensland. The rocks consist of ignimbrite and rhyolite, which are structurally and magmatically related to three high-level intrusions the Herbert River, Esmeralda, and Elizabeth Creek Granites. Most of the igneous rocks intrude the Precambrian Georgetown Inlier, but some of them intrude along a fractured zone on the junction of the Inlier and the shelf zone of the adjacent Palaeozoic Tasman Geosyncline. The Upper Palaeozoic — Triassic igneous period consists of two main epochs, both consisting of granite, ignimbrite, and rhyolite. In both epochs granite intrudes the comagmatic and coeval ignimbrite and rhyolite. Rapid horizontal movement of granitic magma through the epizone and major fracturing of the crust are postulated to explain the widespread intrusion of the granite. The granitic magma was probably initially generated 5 miles below the surface of the crust by partial melting of the sediments at the base of the Tasman Geosyncline. Epeirogenic movement in the Precambrian Inlier area formed sheet-like fractures, which provided channels for rapid horizontal movement of the granitic magma. This magma was emplaced along the fractured marginal zone of the Inlier to form a thick sill-like body of granite — the Herbert River Granite — in the first epoch. Magma for the second epoch was derived from melting of the lower part of the granite of the first epoch. Renewed fracturing of the Inlier area formed cauldron subsidence areas and rift, which were quicly filled with rhyolite and ignimbrite. In these collapsed areas the granitic magma crystallized as the Elizabeth Creek and Esmeralda Granites under an insulating cover of about 1,000 feet of rhyolite and ignimbrite.     

3D Numerical Modeling of the Summit Lake Lava Flow,Yellowstone, USA

Izvestiya, Physics of the Solid Earth - Abstract—Volcanic eruptions belong to the extreme events that change the Earth’s landscape and affect global climate and environment. Although...     

The Amazon River headstream area in the Cordillera Chila,Peru: hydrographic,hydrological and glaciological conditions

Abstract

The source of the world's largest river has fascinated scientists and adventurers for a long time. Extensive studies have been undertaken in the unexplored Llogueta River valley, Cordillera Chila, to identify the main stream of the Amazon River. Analysis of the Lloqueta River network and measurements of its hydrographic and hydrometric characteristics are presented in this study. On the basis of the acquired data, the northern hillside of the Cordillera Chila massif, concretely the basins of four mountainous courses—the Carhuasanta, Apacheta, Ccaccansa and Sillanque rivers—should be regarded as the headwaters territory of the Amazon River. Factors influencing the river system—glaciers and soils—were examined for each catchment. Glacier retreat in the last 50 years has left perennial snowfields only in the highest part of the study area, resulting in modification of the headwater runoff regimes. Preliminary results are afforded by the continual automatic water-level monitoring of the Lloqueta River since June 2008. Our investigations have determined that all types of soil in the area could be classified into two main categories: hydromorphic soils or poorly developed cryic soils.

Citation Janský, B., Engel, Z., Kocum, J., ?efrna, L. & ?esák, J. (2011) The Amazon River headstream area in the Cordillera Chila, Peru: hydrographical, hydrological and glaciological conditions. Hydrol. Sci. J. 56(1), 138–151.     

Polymictic pool behaviour in a montane meadow,Sierra Nevada,CA

We observed polymictic behaviour in stream pools in Long Meadow, Sequoia National Park, California—part of the Southern Sierra Critical Zone Observatory. Stream pools stratified thermally during the day time and were isothermal at night—this pattern persists from the middle of summer into the fall. We found that four characteristics typical of a mountain meadow environment—low stream flow, open sky, cold groundwater discharge, and elevated organic carbon concentrations—are particularly conducive to pool stratification. Incoming shortwave radiation was the dominant energy input to heat pool water while nighttime emitted longwave radiation was the major cooling mechanism. Relatively cold groundwater discharge into the pool bottom increased density stratification within the pool. Elevated DOC concentrations increased the capacity of the pool to absorb photosynthetically active radiation and also promoted stratification. Stream velocities in the meadow were generally insufficient to meet threshold Richardson numbers and mix the pools during the daytime; smaller stream cross sectional areas would have potential for destabilizing pools in the daytime. We propose a conceptual model for describing polymictic stream pools and assessing the potential for polymictic pools to occur. Copyright © 2016 John Wiley & Sons, Ltd.     

Lithosphere thickness,subsidence of aseismic ridges,and volcano height

Two methods — collection of empirical subsidence data for aseismic ridges and observation of the increase in height of oceanic volcanoes with increasing lithospheric age — are used to try to discriminate between the thermal models for the oceanic lithosphere of McKenzie (1967), Parker and Oldenburg (1973), and Crough (1975). Although the volcano height data indicate that thickening of the lithosphere does occur, neither method is precise enough to allow preferential selection of one model over another.     

The digital seismometer, a modern instrument

On the basis of an analysis of the development history of seismometers, the conclusion is made that a new generation of instruments—digital seismometers—should be created. The functions of a digital seismometer and its advantages over other existing instruments are described in brief.     

Variations of Natural Electrical Potentials in the Cryolithozone,Yakutsk

Izvestiya, Physics of the Solid Earth - Abstract—This paper considers daily, seasonal, and interannual variations of natural potentials at two sites in the cryolithozone at the testing...     

The influence of interface geometry,stiffness, and crushing on the dynamic response of masonry collapse mechanisms

Failure of masonry structures generally occurs via specific collapse mechanisms which have been well documented. Using rocking dynamics, equations of motion have been derived for a number of different failure mechanisms ranging from the simple overturning of a single block to more complicated mechanisms. However, most of the equations of motion derived thus far assume that the structures can be modelled as rigid bodies rocking on rigid interfaces with an infinite compressive strength—which is not always the case. In fact, crushing of masonry—commonly observed in larger scale constructions and vertically restrained walls—can lead to a reduction in the dynamic capacity of these structures. This paper rederives the rocking equation of motion to account for the influence of flexible interfaces, characterized by a specific interface stiffness as well as finite compressive strength. The interface now includes a continually shifting rotation point, the location of which depends not only on the material properties of the interface but also on its geometry. Expressions have thus also been derived for interfaces of different geometries, and parametric studies conducted to gauge their influence on dynamic response. The new interface formulations are also implemented within a new analytical modelling tool that provides a novel approach to the dynamic analysis of masonry collapse mechanisms. Finally, this tool is exemplified, along with the importance of the interface formulation, by evaluating the collapse of the Dharahara Tower in Kathmandu, which was almost completely destroyed during the 2015 Gorkha earthquake.     

Seismic,Atmospheric-Wave,Electrical, and Magnetic Effects of Powerful Atmospheric Fronts

Izvestiya, Physics of the Solid Earth - Abstract—Disturbances of seismic noise, magnetic field, electrical characteristics of the surface atmosphere and microbaric variations caused by the...     

New Rock- and Paleomagnetic Data on Quaternary Deposits of the Tologoi Key Section,Western Transbaikalia,and Their Paleoclimatic Implications

Izvestiya, Physics of the Solid Earth - Abstract—An integrated study combining laser granulometry, rock-magnetic, and paleomagnetic investigations is conducted for the deposits of the Tologoi...     

An Investigation into the Earthquake Migration Patterns in Marmara Region,Turkey

Izvestiya, Physics of the Solid Earth - Abstract—The seismic migration patterns can be associated with the existing geophysical setting, the tectonic movements and the geographical...     

Receiver-Function Velocity Structure of the Lithosphere beneath the Khibiny and Lovozero Massifs,Northeastern Baltic Shield

Izvestiya, Physics of the Solid Earth - Abstract—The velocity structure of the lithosphere is studied beneath the Khibiny and Lovozero massifs in the northeastern part of the Baltic shield....