On the selection of GMPEs for Vrancea subcrustal seismic source

The Vrancea subcrustal seismic source is characterized by large magnitude ( $M_{W} \ge 7$ ) intermediate-depth earthquakes that occur two or three times during a century on average. In this study several procedures are used to grade four candidate ground motion prediction equations proposed for Vrancea source in the SHARE project. In the work of Delavaud et al. (J Seismol 16(3):451–473, 2012) four ground motion prediction models developed for subduction zones (Zhao et al. in Bull Seism Soc Am 96(3):898–913, 2006; Atkinson and Boore in Bull Seism Soc Am 93(4):1703–1729, 2003; Youngs et al. in Seism Res Lett 68(1):58–73, 1997; Lin and Lee in Bull Seism Soc Am 98(1):220–240, 2008) are suggested as suitable for Vrancea subcrustal seismic source. The paper presents the appropriateness analysis of the four suggested ground motion prediction equations done using a dataset of 109 triaxial accelerograms recorded during seven Vrancea seismic events with moment magnitude $M_{W}$ between 5.4 and 7.4, occurred in the past 35 years. The strong ground motions were recorded in Romania, as well as in Bulgaria, Republic of Moldova and Serbia. Based on the ground motion dataset several goodness-of-fit measures are used in order to quantify how well the selected models match with the recorded data. The compatibility of the four ground motion prediction models with respect to magnitude scaling and distance scaling implied by strong ground motion dataset is investigated as well. The analyses show that the Youngs et al. (Seism Res Lett 68(1):58–73, 1997) and Zhao et al. (Bull Seism Soc Am 96(3):898–913, 2006) ground motion prediction models have a better fit with the data and can be candidate models for Probabilistic Seismic Hazard Assessment.     

Satellite and ground observations of the June 2009 eruption of Sarychev Peak volcano, Matua Island, Central Kuriles

After 33 years of repose, one of the most active volcanoes of the Kurile island arc—Sarychev Peak on Matua Island in the Central Kuriles—erupted violently on June 11, 2009. The eruption lasted 9 days and stands among the largest of recent historical eruptions in the Kurile Island chain. Satellite monitoring of the eruption, using Moderate Resolution Imaging Spectroradiometer, Meteorological Agency Multifunctional Transport Satellite, and Advanced Very High Resolution Radiometer data, indicated at least 23 separate explosions between 11 and 16 June 2009. Eruptive clouds reached altitudes of generally 8–16 km above sea level (ASL) and in some cases up to 21 km asl. Clouds of volcanic ash and gas stretched to the north and northwest up to 1,500 km and to the southeast for more than 3,000 km. For the first time in recorded history, ash fall occurred on Sakhalin Island and in the northeast sector of the Khabarovsky Region, Russia. Based on satellite image analysis and reconnaissance field studies in the summer of 2009, the eruption produced explosive tephra deposits with an estimated bulk volume of 0.4 km³. The eruption is considered to have a Volcanic Explosivity Index of 4. Because the volcano is remote, there was minimal risk to people or infrastructure on the ground. Aviation transport, however, was significantly disrupted because of the proximity of air routes to the volcano.     

Melt evolution in subarc mantle: evidence from heating experiments on spinel-hosted melt inclusions in peridotite xenoliths from the andesitic Avacha volcano (Kamchatka,Russia)

Glass-bearing inclusions hosted by Cr-spinel in harzburgite xenoliths from Avacha are grouped based on homogenization temperatures and daughter minerals into high-T (1,200°C; opx + cpx), intermediate (900–1,100°C; cpx ± amph), and low-T (900°C; amph) and are commonly accompanied by larger “melt pockets”. Unlike previous work on unheated inclusions and interstitial glass in xenoliths from Kamchatka, the homogenized glass compositions in this study are not affected by low-pressure melt fractionation during transport and cooling or by interaction with host magma. Primary melt compositions constrained for each inclusion type differ in major and trace element abundances and were formed by different events, but all are silica saturated, Ca-rich, and K-poor, with enrichments in LREE, Sr, Rb, and Ba and negative Nb anomalies. These melts are inferred to have been formed with participation of fluids produced by dehydration of slab materials. The high-T inclusions trapped liquids produced by ancient high-degree, fluid-induced melting in the mantle wedge. The low-T inclusions are related to percolation of low-T melts or hydrous fluids in arc mantle lithosphere. Melt pockets arise from localized heating and fluid-assisted melting induced by rising magmas shortly before the entrapment of the xenoliths. The “high-T” melt inclusions in Avacha xenoliths are unique in preserving evidence of ancient, high-T melting events in arc mantle, whereas the published data appear to characterize pre-eruption enrichment events.     

Organic matter governs N and P balance in Danube Delta lakes

The transformation of dissolved inorganic nitrogen (DIN) and soluble reactive phosphorous (SRP), and the release of dissolved organic and particulate N and P, were analyzed in two lake complexes (Uzlina–Isac and Puiu–Rosu–Rosulet) of the Danube Delta wetland during flood conditions in May and at low water level in September 2006. The Uzlina–Isac complex was hydrologically tightly-connected with the Danube River and was flushed with river-borne nutrients and organic matter. These lakes acted as effective transformers for nutrients and produced large amounts of fresh biomass, that promoted the excretion of dissolved organic N and P during active growth. Biomass breakdown created particulate matter (<0.45 μm), which was widely liberated during low flow in the fall. The Puiu–Rosu–Rosulet complex was characterized by a more distant position to the Danube and proximity to the Black Sea, and received dominantly transformed organic compounds from the flow-through water and vast vegetation cover. Due to reduced nutrient input, the internal production of organic biomass also was reduced in these more remote lakes. Total N and P export from the lake nearest to the shelf was governed by dominantly dissolved organic and particulate compounds (mean 58 and 82%, respectively). Overall, this survey found that these highly productive wetlands efficiently transform nutrients into a large pool of dissolved organic and particulate N and P. Hence, wetland lakes may behave widely as net sources of organic N and P to downstream waters and coastal marine systems.     

Niobium-tantalum oxide minerals in the Jezuitsk�� Lesy granitic pegmatite, Bratislava Massif, Slovakia: Ta to Nb and Fe to Mn evolutionary trends in a narrow Be,Cs-rich and Li,B-poor dike

A complex assemblage of Nb-Ta-(Sn) oxide minerals occur in a relatively narrow (~1?2 m thick) extensively albitized, Hercynian granitic pegmatite dike intruding biotite granodiorites near Bratislava, SW Slovakia. The dike shows enrichment in beryl (locally Cs-rich) but absence of Li- and B-rich phases. Compositions and textural relationships indicate complex evolutions of Nb-Ta oxide phases with several generations presenting distinct textural and compositional features. The first generation of the Nb-Ta minerals from the quartz-microcline-muscovite zone show Ta,Fe-rich compositions with Ta# [Ta/(Ta + Nb)]?=?0.52?0.70 (Ct I columbite-tantalite), 0.88?0.90 (Tap I ferrotapiolite) and 0.73?0.86 (Fw I ferrowodginite); Mn# [Mn/(Mn + Fe)]?=?0.32?0.49 (Ct I), 0.06?0.10 (Tap I) and 0.33?0.41 (Fw I). The 2nd generation is represented by ferrocolumbite to ferrotantalite (Ct II) in saccharoidal albite zone, replacement zones of Ct II in Ct I, and irregular overgrowths of ferrotapiolite (Tap II) and ferrowodginite (Fw II) on Tap I grains. The minerals of the 2nd generation show decreasing of Ta# in comparison to the 1st group: 0.10?0.60 (Ct II), 0.85?0.87 (Tap II) and 0.73?0.77 (Fw II); Mn# attains 0.30?0.45 (Ct II), 0.06?0.09 (Tap II) and 0.26?0.37 (Fw II). The 3rd generation includes fissure fillings, overgrowths and replacement zones of manganocolumbite and manganotantalite (Ct III), ferrotapiolite (Tap III) and ferrowodginite (Fw III) on the older Nb-Ta phases (Ct I, Tap I, Fw I, Fw II), in the coarse-grained unit. The 3rd population displays distinct Mn# increasing (Ct III: 0.51?0.69, Tap III: 0.11?0.24, Fw III: 0.40?0.41), Ta# values reach 0.16?0.79 (Ct III), 0.88?0.92 (Tap III) and 0.80?0.81 (Fw III). The latest, 4th generation of the Nb-Ta phases represents irregular veinlets and patches of fluorcalciomicrolite, replacing Ct I, Tap I, Fw I, Ct II and Tap III. Decrease of Ta/(Ta + Nb) values in Ct II from the saccharoidal albite unit can be explained by crystallization from the albite-rich melt, which was significantly impoverished in Ta with respect to Nb, after crystallization of Ta-rich phases from the 1st generation (ferrotapiolite I, ferrowodginite I).     

Integral transformations of deflections of the vertical onto satellite-to-satellite tracking and gradiometric data

With the advent of geodetic satellite missions mapping almost globally the Earth’s gravitational field, new methods and theoretical approaches have been developed and investigated to fully exploit the potential of their new observables. Besides estimating values of numerical coefficients in harmonic series of the gravitational potential, new applications emerged such as data validation and combination. In this contribution, new integral transformations are presented which transform principal components of the terrestrial deflection of the vertical onto disturbing satellite-to-satellite tracking and gradiometric data at altitude. Using spherical approximation, necessary integral kernel functions are derived in both spectral and closed forms. The behaviour of isotropic kernel functions is studied and the new integral transformations are tested in a closed-loop simulation using synthetic terrestrial and satellite data synthesized from a global gravitational model. New integral transformations can be used for data validation and combination purposes.     

Thermal state of ice-rich soils on the Tommot-Yakutsk Railroad right-of-way

This paper summarizes the results of investigations carried out in the northern section of the Tommot-Yakutsk Railroad in eastern Siberia, underlain by ice-rich permafrost. The ongoing permafrost and geotechnical research program in support of railroad construction includes assessment of the ground thermal state on the right-of-way and adjacent areas based on long-term field observations using the method of terrain thermal physics. These studies focus on the upper permafrost within the depth of annual temperature variation. In undisturbed areas, inter-annual variability of the ground thermal state shows little response to recent climatic variations. However, forest clearing and surface disturbance during right-of-way construction cause an increase in permafrost temperature, deepening of the active layer, thaw settlement, and water accumulation along the embankment. The active layer is thickest along the sun-exposed left berm and is thinnest along the more shaded right berm. Measures to prevent thaw-related embankment problems are recommended.     

Mercury speciation in soil in vicinity of coal beds using sequential extraction

The sequential extraction procedure was proposed and used to study of mercury speciation in real samples of soil. Samples of soil profiles together with bedrock and coal were taken from sampling spots in the vicinity of surficial coal beds in an area with natural coal outcrops. The proposed sequential extraction procedure involves the following fractionation: organic mercury compounds, extractable mercury in an acidic medium, mercury bound to humic substances, elemental Hg and mercury bound to complexes, HgS and residual mercury. The significant distribution of mercury between the two portions—mercury bound to humic substance and HgS was determined in the majority of samples. The mercury bound to humic substances created a significant contribution, especially to the top layer of soil. On the other hand, HgS was the dominant form in the samples from lower layers of the soil profile. The mercury content in the samples did not show a distinct mobility. The influence of soil parameters on the mercury distribution in the studied samples was investigated and discussed.     

Aquifer characterization using shallow geophysics in the Keritis Basin of Western Crete, Greece

Effective management of groundwater resources is a well-known problem in several areas around the world. It is especially important to areas suffering from an intrinsic lack of fresh water, such as islands. Detailed study of available aquifers is of particular interest in the highly touristic Greek island of Crete. The increasing water demand makes water resources management extremely important for sustainable development. This is the case in the prefecture of Chania in Western Crete, where there has been a lack of success of many different groundwater management plans that have been produced over the years and submitted for application to water management authority. The inefficiency of the management plans is verified by the continuous water shortage reported every year which forces the public authorities to transfer water from far away sources and wells. Until today there are only geological data as well as information from the borehole logs; therefore, the current work is focused to study in detail the tectonic and hydrogeological characteristics of the Keritis watershed to make a correlation of the available geoenvironmental information with the geophysical data of the study aquifer. Transient electromagnetic soundings were conducted to obtain detailed information about: the tectonic, hydrogeological, hydrolithological, and geometrical characteristics of the aquifer under investigation. In addition, optimum areas of water well drilling were identified to minimize the uncertainty and the total cost (economical, managerial, etc.) of future groundwater surveys.