The field-emission (FE) properties of molybdenum disulfide nanotubes (NTs) are reported for the single-tip geometry. Reproducibly stable FE currents in excess of 10 μA were measured from single NT tips in vacuum of 10−7 mbar. Valuable characteristics of the nanotube material are ease of processing and reproducibility of the FE properties.
Summary To constrain seismic anisotropy under and around the Alps in Europe, we study SKS shear-wave splitting from the region densely covered by the AlpArray seismic network. We apply a technique based on measuring the splitting intensity, constraining well both the fast orientation and the splitting delay. 4 years of teleseismic earthquake data were processed, from 723 temporary and permanent broadband stations of the AlpArray deployment including ocean-bottom seismometers, providing a spatial coverage that is unprecedented. The technique is applied automatically (without human intervention), and it thus provides a reproducible image of anisotropic structure in and around the Alpine region. As in earlier studies, we observe a coherent rotation of fast axes in the western part of the Alpine chain, and a region of homogeneous fast orientation in the Central Alps. The spatial variation of splitting delay times is particularly interesting though. On one hand, there is a clear positive correlation with Alpine topography, suggesting that part of the seismic anisotropy (deformation) is caused by the Alpine orogeny. On the other hand, anisotropic strength around the mountain chain shows a distinct contrast between the Western and Eastern Alps. This difference is best explained by the more active mantle flow around the Western Alps. The new observational constraints, especially the splitting delay, provide new information on Alpine geodynamics.
SUMMARY We infer seismic azimuthal anisotropy from ambient-noise-derived Rayleigh waves in the wider Vienna Basin region. Cross-correlations of the ambient seismic field are computed for 1953 station pairs and periods from 5 to 25 s to measure the directional dependence of interstation Rayleigh-wave group velocities. We perform the analysis for each period on the whole data set, as well as in overlapping 2°-cells to regionalize the measurements, to study expected effects from isotropic structure, and isotropic–anisotropic trade-offs. To extract azimuthal anisotropy that relates to the anisotropic structure of the Earth, we analyse the group velocity residuals after isotropic inversion. The periods discussed in this study (5–20 s) are sensitive to crustal structure, and they allow us to gain insight into two distinct mechanisms that result in fast orientations. At shallow crustal depths, fast orientations in the Eastern Alps are S/N to SSW/NNE, roughly normal to the Alps. This effect is most likely due to the formation of cracks aligned with the present-day stress-field. At greater depths, fast orientations rotate towards NE, almost parallel to the major fault systems that accommodated the lateral extrusion of blocks in the Miocene. This is coherent with the alignment of crystal grains during crustal deformation occurring along the fault systems and the lateral extrusion of the central part of the Eastern Alps.
The project RI-SI-EPOS (Research Infrastructure-Slovenia-European Plate Observing System) provided new scientific equipment for solid Earth science related to geology, seismology, geodesy and karstology. Karst research infrastructure is primarily used at the SLO KARST NFO (Near Fault Observatory) developing site. The area covers ~ 2600 km2 and is one of the most seismically active areas in SW Slovenia. It consists mostly of karstified Mesozoic carbonate rocks and partly of non-karstified Eocene flysch. The landscape has numerous karst features including caves, poljes, dolines, uvalas, karst springs, ponors and periodic karst lakes, with typical karst underground water drainage. Site development commenced with the installation of seven temporary seismic stations in the area, along with other geoscience equipment (gravimeter, 3D laser terrestrial scanner, GNSS antenna, TM72 extensometers, spectrometer for methane and drone), deployed in 2020. With the new dense seismic network, locations and other seismic parameters are already determined more reliably than in the past, contributing to a better understanding of active tectonic deformations at the junction between the seismically active Friuli region (Italy) and the Zagreb–Petrinja area (Croatia). The new solid Earth Geoscience research infrastructure is already collecting a big amount of data following the FAIR principles (making data Findable, Accessible, Interoperable and Reusable) aiming to be included in the national and international research databases. Here, the first results from the newly operating SLO KARST NFO temporary seismic network (May 2020–June 2021) are discussed.
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