Generation of the teleseismic P-wave coda from Aleutian earthquakes

We investigate large-amplitude phases arriving in the P -wave coda of broad-band seismograms from teleseisms recorded by the Gräfenberg array, the German Regional Seismic Network and the Global Seismic Network. The data set consists of all events m _b≤ 5.6 from the Aleutian arc between 1977 and 1992. Earthquakes with large-amplitude coda waves correlate with the presence of oceanic crust in the source region. The amplitudes sometimes approach those of the P wave, much larger than predicted by theory. Modelling indicates that phases in the P -wave coda cannot be P -wave multiples beneath the source and receiver, or underside reflections, which precede PP , from upper-mantle discontinuities. Among the events, seismograms are very similar, where the arrival times of the unusual phases agree approximately with the predicted times of S -to- P conversions from the upper-mantle discontinuities under the source. Because the large-amplitude phases in the P -wave coda have little, if any, dependence on event depth and have predominantly an SV -wave radiation pattern towards the receiver, we suggest that they originate as SV and/or Rayleigh waves and are enhanced by lateral heterogeneity and multipathing from the subducting Aleutian slab.     

Effects of long-range transport on atmospheric trace constituents at the baseline station tenerife (Canary Islands)

First results of baseline observations from the new BAPMoN station Tenerife give information about the atmospheric background in this latitude of about 25° N in the North Atlantic. The influence of the meridional exchange with the northern part of the hemisphere as well as transport from the African continent is evident. Changes of air mass are strongly reflected in the concentration records of carbon dioxide, methane, and ozone depending on the seasonal and meridional distribution of these components. Transport of Sahara dust results in an increase of optical thickness and an ozone depletion. According to the seasonal frequency of characteristic transport conditions, these influences are reflected in the annual cycle of the records.     

Ergebnisse einer magnetischen und gravimetrischen Engvermessung in der nordostatlantischen Tiefsee

Ohne Zusammenfassung     

A statistical model of proton binding by humus

A model that considers both the carboxyl and weakly acidic groups of humus as continuous binding site distributions in which individual ligand concentrations are normally distributed with respect to the log $\text{K}$ values for proton binding is proposed. The concentration, mean log $\text{K}$ value, and variance for the log $\text{K}$ distribution of each class of functional groups are estimated by nonlinear regression analysis of titration data. The values obtained for those parameters are chemically reasonable and the extent of proton binding between pH 4.0 and pH 10.8 is accurately described by the model.     

Spline approximation for TALWANI's method of magnetic anomaly computation

When using TALWANI's method for computing magnetic anomalies of three-dimensional bodies unexpected errors may occur. They are caused by the numerical depth integration. It is shown how those errors can be recognized and reduced by employing spline approximations.     

Variscan amphibolite-facies rocks from the Kurtoğlu metamorphic complex (Gümüşhane area,Eastern Pontides,Turkey)

The Kurtoğlu metamorphic complex, that forms part of the pre-Liassic basement of the Sakarya zone in northern Turkey, consists of at least two tectonic units. Blueschist-facies rocks of unknown metamorphic age in the southern part of the complex are tectonically overlain by Variscan low-pressure high-temperature metamorphic rocks. The latter comprise mica schists and fine-grained gneisses, cut by metaleucogranitic dikes, as well as migmatitic biotite gneisses and subordinate amphibolite intercalations. Structural data indicate that metamorphism and penetrative deformation occurred after dyke intrusion. Peak metamorphic conditions of the mica schists, fine-grained gneisses and metaleucogranites are estimated to ∼650°C and ∼0.4 GPa, based on phase relationships in the system NCKFMASH, Fe–Mg partitioning between garnet and biotite as well as garnet-aluminosilicate-quartz-plagioclase (GASP) and garnet-plagioclase-biotite-quartz (GBPQ) barometry. Peak temperatures of the migmatitic biotite gneisses and amphibolite intercalations are not well constrained but might have been significantly higher (690–740°C), as suggested from hornblende-plagioclase thermometry. ⁴⁰Ar–³⁹Ar incremental dating on muscovite and biotite fractions from the mica schists and fine-grained gneisses yielded plateau ages of ∼323 Ma. Significantly older model ages of ∼329 and ∼337 Ma were obtained on muscovite fractions from two metaleucogranite samples. These fractions contain both relict igneous and newly formed metamorphic muscovite.     

Fate of Benzalkonium Chloride in a Sewage Sludge Low Temperature Conversion Process Investigated by LC‐LC/ESI‐MS/MS

Thermocatalytic low temperature conversion (LTC) is a new method for the disposal of sewage sludge. Using this method, sludge is converted into a residual solid (coal) along with reaction water, oil, and non‐condensable gases. The oil can be used as an energy source and the coal as a substitute for charcoal. To this end, it is important to determine whether there are any easily available contaminants present in the coal generated by the process. Contaminants that can be strongly sorbed by sewage sludge solids are, e. g., pharmaceuticals and disinfectants. As an example the fate of the persistent and strong adsorbing disinfectant benzalkonium chloride (BAC) has been investigated within the LTC process. The sewage sludge was spiked with BAC and then subjected to the LTC process. The resulting coal was extracted and analyzed using LC‐LC/ESI‐MS/MS (ion trap). BAC could not be detected in the LTC coal, although it could be extracted from the spiked sludge before the LTC treatment. It can thus be concluded that the investigated compound is not easily available in the coal, and hence that its use does not present a risk.     

3D mapping as a tool for the planning of preservation measures on sculptures made of natural stone

The article deals with the comparison between 2D and 3D evaluation of surface areas of sculptures. The objects chosen for investigation were Apollo (Carrara Marble, Potsdam Sanssouci), Flora (Laas Marble, Castle and Park Nymphenburg Munich) and Juno (Cotta Sandstone, Baroque Garden Großsedlitz/Dresden). Photographs showing the sculptures from all sides were used for calculating 2D surface areas with AutoCAD 2018 software. 3D models were generated with T-Scan 2 (Steinbichler Company), and 3D surface areas were evaluated with CAD software Geomagic Studio. The results show that 3D total surface area determinations of virtual 3D models are much more precise than 2D determinations on photographs. The values of the total surface area differ significantly. In case of Apollo 2D measurement captures only 66% of the real total surface. For measuring surface roughness, standardized Bosch sandpapers with P classification were used. Microphotographs of marble and sandstone surfaces show the development and the general optical appearance of increasing roughness. As expected, 2D calculation gives smaller values than 3D calculation also in case of surface roughness. In case of Apollo the P400 roughness area calculated with 2D measurement yields only 26% of the real area calculated with 3D. The accuracy of the surface 2D measurement clearly depends on the complexity of the sculpture because undercuts cannot be captured on photographs. It is shown that accurate information about the distribution of damage phenomena helps to improve planning conservation measures.