Preliminary Results of Anthropogenic Seismicity Monitoring in the Region of Song Tranh 2 Reservoir,Central Vietnam

Song Tranh 2 hydropower plant and the reservoir containing backed up water are located in the Quang Nam province (Central Vietnam). The region experiences unusual seismic activity related to the reservoir impoundment, with earthquakes of magnitude up to 4.7. In result of cooperation between the Institute of Geophysics, Vietnam Academy of Sciences and Technology and the Institute of Geophysics, Polish Academy of Sciences a seismic network has been built to facilitate seismic monitoring of the Song Tranh 2 area. The network, operating since August 2013, consists of 10 seismic stations. Here we show that the network is sufficient for advanced data processing. The first results of monitoring of the earthquake activity in Song Tranh 2 area in the period between 2012 and 2014, especially the completeness of catalogs, study and comparisons between water level and the seismic activity suggest direct connection between reservoir exploitation and anthropogenic seismicity.     

Contribution of rock magnetism to stratigraphy and palaeoenvironment of the Karaïn cave infill,Antalya, Turkey

The magnetic properties of the infill of the Karaïn cave in Turkey were compared to the results of a sedimentological study on three longitudinal sections. The sediments of this site, namely cavity E, cover a period of ca. 500 ka and correspond to a large part of the Middle and Upper Pleistocene. The evolution observed for the various magnetic parameters is mainly related to climatic changes which followed one another during the infilling history of the cave. Two preconditions are necessary to understand the environmental magnetism, namely both the identification and the quantification of different magnetic phases (components) in the sediments, expressed by the ratio of the various magnetic parameters and the analysis of the magnetization curves. The results obtained through the study of the different magnetic parameters (low-field initial bulk (κ_lf) and mass (χ_lf) magnetic susceptibility, frequency dependence of the magnetic susceptibility (χ_fd), anhysteretic remanent magnetization (ARM), hysteresis parameters, anhysteretic susceptibility, ...) on 171 samples allowed us: 1 — to follow the nature, size and source of the grains at each level, and 2 — to identify six alternating levels, having different magnetic susceptibility signatures during warm, damp periods, in which the contribution of prehistorical hominidae (Homo Sapiens or Homo Neandertalensis) and animals, could have modified the original sedimentary structures.This study, in agreement with the sedimentological results, suggests a significant difference between sandy or sandy-silty levels (3 and 5) and those rich in clays and concretions. The sandy or sandy-silty levels are mainly characterized by a low amount of antiferromagnetic type grains, likely goethite and hematite, dominated by single-domain size (SD) and a small content of ferrimagnetic type grains, likely magnetite of multidomain size (MD), inherited from the host rock. Antiferromagnetic grains did not develop and were a priori drifted by the wind. They could be contemporaneous with a cold climate.The clays and clayey-silty levels are characterized by a large amount of superparamagnetic (SP) and SD grains, and a high content of low coercivity magnetic grains (magnetite, maghemite and Ti-magnetite). The saturation remanent magnetization (SIRM) of clayey levels is 5 to 10 times higher than that of sandy levels. The clayey levels are contemporaneous with a humid climate, which favoured the formation of secondary iron oxides, of stalagmitic floors and calcite concretions and of the emplacement of local pedogenesis phenomena, mainly at the top of the infill, i.e. in Level 6.     

A review of the metallogeny and tectonics of the Lachlan Orogen

Future mineral exploration within eastern Australia will be enhanced by resolving the tectonic evolution of the Lachlan Orogen to establish the spatial and temporal terrane distribution of the various mineral deposits. The Lachlan Orogen, from north-eastern Tasmania through to central and eastern New South Wales, is host to a number of major mineral deposit styles—including orogenic gold (e.g. Stawell, Ballarat, Bendigo), volcanic-hosted massive sulphide (e.g. Woodlawn, Currawong), sediment-hosted Cu–Au (e.g. Cobar Basin deposits), porphyry Au–Cu (e.g. Cadia, Parkes, Cowal) and granite-related Sn (e.g. Ardlethan, Beechworth). Each of these mineral deposit styles is a sensitive and diagnostic indicator of the prevalent tectonic environment during their formation. In this review, we briefly summarise the deposit- to large-scale factors that define the diverse metallogenic evolution of the Lachlan Orogen. This overview is intended to “set the scene” for subsequent specialist papers published in this thematic issue on the metallogeny and tectonics of the Lachlan Orogen in south-east Australia.     

Performance evaluation of correction coefficients to optimize sediment rating curves on the basis of the Karkheh dam reservoir hydrography,west Iran

The prediction of useful lifetime of a dam is estimated through accurate estimate of river sediments which mostly depend on sediment rating curve. Over the past decades, various methods have been developed by investigators. With respect to the importance of this issue, in the present study, the best discharge-sediment relationship for Jelogir hydrometric station located at the upstream of Karkheh reservoir dam is presented. In the first step, sediment rating curves in annual, seasonal, monthly, wet and dry, and middle of the classes linear ways and applying 3 correction coefficients that include Smearing, FAO, and QMILE were obtained; then, their performance was evaluated. Comparison of these results with data obtained from hydrographical operation of Karkheh dam reservoir showed that the optimal equation of discharge-sediment at this hydrometric station follows annual linear sediment rating curve with QMILE correction coefficient. According to the results, annual method has estimated sediment volume less than the actual volume, about 98.7% of the actual sediment, while other evaluated methods have showed sediment volume more than the actual one, and among correction coefficients, the application of QMILE correction coefficient is more reasonable than other coefficients.     

Groundwater nitrate vulnerability assessment in alluvial aquifer using process-based models and weights-of-evidence method: Lower Savinja Valley case study (Slovenia)

This paper describes the implementation of process-based models reflecting relative groundwater nitrate vulnerability of the shallow alluvial Lower Savinja Valley (LSV) aquifer in Slovenia. A spatially explicit identification of the potentially vulnerable priority areas within groundwater bodies at risk from a chemical point of view is being required for cost-effective measures and monitoring planning. The shallow LSV unconfined aquifer system consists of high-permeable Holocene and middle- to low-permeable Pleistocene gravel and sand, with a maximum thickness of about 30 m, mainly covered by shallow eutric fluvisoils or variously deep eutric cambisoil. The hydrogeological parameters, e.g. the depth to the groundwater, hydrological role of the topographic slope, etc. usually used in different point count schemes are, in the case of the lowland aquifer and shallow groundwater, spatially very uniform with low variability. Furthermore, the parametric point count methods are generally not able to illustrate and analyze important physical processes, and validation of the results is difficult and expensive. Instead of a parametric point count scheme, we experimentally used the Arc-WofE extension for weights-of-evidence (WofE) modelling. All measurement locations with a concentration higher than the value of 20 mg NO₃ ⁻ per litre of groundwater have been considered as training points (173), and the three process-based models generalized output layers of groundwater recharge (GROWA), nitrate leached from the soil profile (SWAT) and groundwater flow velocity (FEFLOW), served as evidential themes. The technique is based on the Bayesian idea of phenomena occurrences probability before (prior probability) and after consideration of any evidential themes (posterior probability), which were measured by positive and negative weights as an indication of the association between a phenomena and a prediction pattern. The response theme values describe the relative probability that a 100 × 100 m spatial unit will have a groundwater nitrate concentration higher than the training points’ limit values with regard to prior probability value. The lowest probability of groundwater nitrate occurrence is in the parts of the LSV aquifer, which are known as anoxic condition areas with very likely denitrification processes. The cross-validation of the dissolved oxygen and dissolved nitrate response theme confirmed the accuracy of the groundwater nitrate prediction. The WofE model results very clearly indicate regional groundwater nitrate distribution and enable spatial prediction of the probability for increased groundwater nitrate concentration in order to plan the groundwater nitrate reduction measures and optimize the programme for monitoring the effects of these measures.     

A Global Terrestrial Reference Frame from simulated VLBI and SLR data in view of GGOS

In this study, we assess the impact of two combination strategies, namely local ties (LT) and global ties (GT), on the datum realization of Global Terrestrial Reference Frames in view of the Global Geodetic Observing System requiring 1 mm-accuracy. Simulated Very Long Baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR) data over a 7 year time span was used. The LT results show that the geodetic datum can be best transferred if the precision of the LT is at least 1 mm. Investigating different numbers of LT, the lack of co-located sites on the southern hemisphere is evidenced by differences of 9 mm in translation and rotation compared to the solution using all available LT. For the GT, the combination applying all Earth rotation parameters (ERP), such as pole coordinates and UT1-UTC, indicates that the rotation around the Z axis cannot be adequately transferred from VLBI to SLR within the combination. Applying exclusively the pole coordinates as GT, we show that the datum can be transferred with mm-accuracy within the combination. Furthermore, adding artificial stations in Tahiti and Nigeria to the current VLBI network results in an improvement in station positions by 13 and 12%, respectively, and in ERP by 17 and 11%, respectively. Extending to every day VLBI observations leads to 65% better ERP estimates compared to usual twice-weekly VLBI observations.     

Extracting flow structures from tracer data

A method of visualizing structures in closed chaotic flows out of homogenous particle distributions is presented in the example of models of a meandering jet. To this end, the system will be leaked or opened up by defining a region of the flow, so that a particle is considered to be escaped if it leaves this region. By applying this method to an ensemble of nonescaped tracers, we are able to characterize mixing processes by visualizing the converging and stretching filamentations (stable and unstable manifolds) in the flow without using additional mathematical tools. The possibility of applying the algorithm to analyze buoy data, and a comparison with the finite time manifolds are discussed.     

大功率激电测深法寻找焦家式深部金矿床的试验应用研究

利用大功率的激电测深法可以寻找焦家式深部金 矿。首先,由物理和数学推导建立多层极化体的数 理模型,其数理模型产生的极化场可由多层若干 个极化单元场相叠加而成。由多次去除极化单元 场的原理而导出大功率激电测深资料进行消除浅 部强激电干扰异常的数据处理公式,从而突出了 深部矿床的激电异常。并利用处理后的激电测深 曲线,定量求取了深部金矿蚀变矿化带的顶界面 埋深。     

Physics of basic motions in asymmetric continuum

We consider the advantages of a formalism based on concept of the asymmetric continuum and we present some equivalence theorems relating it to the asymmetric elasticity and to micropolar and micromorphic theories as founded by Nowacki, Cosserats and Eringen. We consider the basic processes in an asymmetric continuum which could be reduced to the point basic motions/deformations. The co-action of spin and shear motions is assumed to play the main role in fracturing process, while the constitutive relation between the antisymmetric stresses and rotations replaces the friction constitutive law.     

Upstream—Downstream Shifts in Peak Recruitment of the Native Olympia Oyster in San Francisco Bay During Wet and Dry Years

Understanding the conditions that drive variation in recruitment of key estuarine species can be important for effective conservation and management of their populations. The Olympia oyster (Ostrea lurida) is native to the Pacific coast of North America and has been a target of conservation efforts, though relatively little information on larval recruitment exists across much of its range. This study examined the recruitment of Olympia oysters at biweekly to monthly intervals at four sites in northern San Francisco Bay from 2010 to 2015 (except 2013). Mean monthly temperatures warmed at all sites during the study, while winter (January–April) mean monthly salinity decreased significantly during a wet year (2011), but otherwise remained high as a result of a drought. A recurring peak in oyster recruitment was identified in mid-estuary, in conditions corresponding to a salinity range of 25–30 and >16 °C at the time of settlement (April–November). Higher average salinities and temperatures were positively correlated with greater peak recruitment. Interannual variation in the timing of favorable conditions for recruitment at each site appears to explain geographic and temporal variation in recruitment onset. Higher winter/spring salinities and warmer temperatures at the time of recruitment corresponded with earlier recruitment onset within individual sites. Across all sites, higher winter/spring salinities were also correlated with earlier onset and earlier peak recruitment. Lower winter salinities during 2011 also resulted in a downstream shift in the location of peak recruitment.