Travel times of seismic waves propagating to the bohemian massif from the south-west direction

mau x¶rt; u a¶rt;u 8 ¶rt;nu mau ¶rt; uu mu u -ana¶rt; auu naa num mam u u na n, g, Sn u Sg mum ma¶rt;am¶rt;a ¶rt; uu mu. a¶rt;u lam mu aua u umau u mm u a amuu ¶rt; En.     

A model of the lithosphere thickness in the region of the Carpathians

Summary Directionally independent average P residuals computed for waves of teleseismic events arriving under various azimuths and incidence angles provided the basis for estimating the lithosphere thickness beneath the Carpathians and their surroundings. A thin lithosphere (60–80 km) was determined for the Pannonian Basin and the Transylvanian Basin, the thickest lithosphere(about 180 km) beneath the South Carpathians at the contact with the Moesian Platform. In other parts of the Carpathian belt the lithosphere thickens beneath the outer parts towards the SW margin of the East-European and the Moldavian Platforms. The lithosphere thicknesses derived from P residuals correlate well with the magnetotelluric determinations of a layer of increased electrical conductivity in the upper mantle.

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Резюме Осре?rt;ненные временные невязкu Р волн, незaвuсuмые оm нanрaвленuя u рaссчumaнные ?rt;ля у?rt;aленных землеmрясенuŭ uз волн, nрuхо?rt;ящuх nо?rt; рaзнымu aзuмуmaмu u у лaмu na?rt;енuя, ?rt;aюm основaнuе ?rt;ля оnре?rt;еленuя мощносmu лumосферы Кaрnam u uх окресmносmеŭ. Тонкaя лumосферa(60–80 км) оnре?rt;еленa ?rt;ля Пaннонско о u Трaнсuльвaнско о бaссеŭнов, a сaмaя мощнaя лumосферa(около 180 км) нaхо?rt;umся nо?rt; Южнымu Кaрnamaмu. В ?rt;ру uх чaсmях Кaрnamско о nоясa мощносmь лumосферы нaрaсmaеm во внешнuх зонaх в нanрaвленuu к ю о-зana?rt;ноŭ окрauне Восmочно-Евроnеŭскоŭ u Мол?rt;aвскоŭ nлamформ. Нaблю?rt;aеmся хорошaя корреляцuя мощносmu лumосферы, оnре?rt;еленноŭ нa основе невязок временu Р волн, с мa нumоmеллурuческuмu ?rt;aннымu nо лубuне слоя nовышенноŭ элекmроnрово?rt;uмосmu в верхнеŭ мaнmuu.

     

Regional fabric of the deep lithosphere in central Europe from seismic anisotropy

Summary The large scale anisotropic structures with plunging symmetry axes in the subcrustal lithosphere of central Europe were derived from independent observations of teleseismic P-residual spheres and polarizations of the split SKS waves. The dipping structures are interpreted as remnants of palaeo-subduction systems which retain olivine orientations from ancient oceanic lithosphere. Values of k_P and k_S estimated from observed teleseismic P and SKS data are within the range of anisotropies found for the upper mantle rocks. The Variscides of central Europe may thus be characterized by two palaeo-subduction systems, with symmetry axes divergent relative to the suture between the Moldanubicum and Saxothuringicum.     

Saxothuringian-Moldanubian Suture and Predisposition of Seismicity In The Western Bohemian Massif

We modelled the thickness and seismic anisotropy of the subcrustal lithosphere from the variations of P-wave delay times and the shear-wave splitting observed at seismological observatories and portable stations in the western part of the Bohemian Massif. The Saxothuringian lithosphere is characterized by a total thickness between 90 and 120 km, the Moldanubian lithosphere is generally thicker –120-140 km, on the average. The subcrustal lithosphere of both units is characterised by divergently dipping anisotropic structures and the suture between them is marked by a lithosphere thinning to about 80km. Within the subcrustal lithosphere a complex structure of the transition of both units extends to about 150 km toward the south. We suggest that the Saxothuringian-Moldanubian suture has created a zone of mechanical predisposition for the Tertiary Ohe (Eger) Graben, as well as for the occurrence of earthquake swarms in the region. Most earthquakes occur within the brittle part of the upper crust above the crossing of the suture between the Saxothuringian in the north and the Moldanubian and the Tepl´-Barrandian in the south, with the tectonically active Mariánské Lázn fault.     

The Mechanism of Reactive NO3 Uptake on Dry NaX (X=Cl, Br)

A simple kinetic mechanism of nitrate radicals uptake on dry sea-salt NaCl, NaBr surfaces is proposed. The mechanism includes adsorption/desorption equilibrium and unimolecular decomposition of the adsorbed complex: NO₃(g) + NaX(s) (NO₃-NaX)(s); (NO₃-NaX)(s) NaNO₃ + X(s) Two techniques were used: the matrix isolation ESR and mass spectrometry. The uptake coefficient () is found to be dependent on exposure time of salt to NO₃ for raw coating. The initial (t0) is higher than the observable steady-state _obs. At room temperature _obs is independent of [NO₃] at low [NO₃] = 3 × 10⁹ - 10¹¹ cm^-3, but it is inversely proportional to [NO₃] at concentrations higher than 10¹² cm^-3. At temperatures above 100 °C, _obs becomes independent of [NO₃] in a wider range of [NO₃]. An increased number of dislocations is supposed to exist in the case of raw coating. Due to a wide spread of the surface sites binding energy with the ionic lattice near dislocations, the part of surface complexes has lower binding energy and "burns" more rapidly. That burning determines the transition from (t0) down to _obs.The kinetic parameters and elementary rate coefficients are obtained. The recommended for low atmospheric NO₃ concentration are in the range of 0.002 ± 0.04 for NaCl and 0.1-0.3 for NaBr depending on a mechanism of the (t) relaxation.     

Effect of small potassium-rich dykes on regional gamma-spectrometry image of a potassium-poor volcanic complex: A case from the Doupovské hory Volcanic Complex, NW Czech Republic

Basaltic rocks with low K, U and Th contents dominate the entire Volcanic Complex of the Doupovské hory Mts. Significant potassium anomaly exceeding 1.5 atomic wt.% of potassium over an area of 4 × 8 km and 2 atomic wt.% of potassium over an area of 2 × 6 km was defined by airborne gamma-ray spectrometry above the central part of the Doupovské hory Volcanic Complex. The following detailed field study, supported by field and laboratory gamma-spectrometry measurements and geochemical analyses of rock samples, resulted in discovery of a swarm of potassium-rich trachytic dykes. The existence of such highly-differentiated rocks in the volcanic complex was unknown till present. These dykes are commonly less than 1 m wide, but their potassium content varies between 4 and 8 atomic wt.%. Owing to this high-K composition and relative abundance of dykes, the dyke rocks significantly modify the regional pattern of gamma-spectrometry data. The potassium anomaly cannot be explained by the presence of Flurbühl intrusive body dominated by ijolites and essexites, as all these rocks are poor in K, with potassium typically not exceeding 1.5 wt.%. On the other hand, much more extensive intermediate trachybasaltic lavas with K content varying within the range 1.8–3 wt.% cause only minor or undetectable anomalies.     

Dynamics of “jumping” Trojans: a perturbative treatment

The term “jumping” Trojan was introduced by Tsiganis et al. (Astron Astrophys 354:1091–1100, 2000) in their studies of long-term dynamics exhibited by the asteroid (1868) Thersites, which had been observed to jump from librations around \(L_4\) to librations around \(L_5\). Another example of a “jumping” Trojan was found by Connors et al. (Nature 475:481–483, 2011): librations of the asteroid 2010 TK7 around the Earth’s libration point \(L_4\) preceded by its librations around \(L_5\). We explore the dynamics of “jumping” Trojans under the scope of the restricted planar elliptical three-body problem. Via double numerical averaging we construct evolutionary equations, which allow analyzing transitions between different regimes of orbital motion.     

A Numerical Algorithm for Time Integration of the Problems of Ideal Magnetohydrodynamics Based on Analyticity of Their Solutions

Izvestiya, Physics of the Solid Earth - Abstract—We show that a solution of the system of three-dimensional equations of ideal magnetohydrodynamics is analytic in the spatial and temporal...     

Event-scale pebble mobility observed by RFID tracking in a pre-Alpine stream: a field laboratory

Understanding coarse sediment transport is crucial for the prediction of sediment migration and the consequent development of fluvial morphologies. In this study, cobble displacements in a pre-Alpine creek have been recorded by means of radio frequency identification (RFID). Pebble monitoring has been systematically performed after each rainfall event with moderate precipitation, in order to exclude the superimposition of sediment displacements induced by triggering factors acting at different times. The analysis of the collected data was carried out through the application of both a principal component analysis and the Buckingham Π theorem. The experimental trends were interpreted considering the ratio of mobile pebbles, the pebbles' displacement and virtual velocity as the dependent variables. These quantities mostly depend on the event peak discharge, with a nonlinear increase of the travelled distance and a growth of up to two orders of magnitude of the virtual velocity (for an approximately 10× increase in peak discharge). An inverse dependency of the virtual velocity on the event duration was also observed. A comparison of the results obtained with those from laboratory investigations of bedload transport mechanics evidenced the differences in parametric trends associated with sediment mobility in the two environments. This contrast brings forward the combination of multiple drivers of sediment mobility, such as local morphology, sediment dimensions and flow unsteadiness, warranting a further in-depth investigation. Representation of results in a dimensionless form is suggested as a good practice to analyse data from case studies characterized by different scales. © 2019 John Wiley & Sons, Ltd.