Technogenic-tectonic earthquakes of the Dnieper–Donets aulacogen

The Mikhnevo Seismic Group of the Institute of Geosphere Dynamics, Russian Academy of Sciences (IGD RAS), and the Malin mini-group in the region of the Dnieper–Donets aulacogen, within which prospecting and mountain-explosion works were carried out from 2007 to 2015 on industrial scales, recorded a series of seismic events. Special attention has been focused on analysis of the nature of three earthquakes in 2015. Application of the spectral discrimination method log(Pg/Lg) and cross-correlation tools allowed us to identify the seismic events in 2015 as a special technogenic-tectonic type.     

Arctic climate changes in the 21st century: Ensemble model estimates accounting for realism in present-day climate simulation

In the course of forecasting future climate changes in the Arctic Region based on calculations and an ensemble of the state-of-the-art global climate models, the results depend on the method of construction the statistics from the models.     

The Ozernoye meteorite: New data on mineralogy

New data on the mineral composition of the Ozernoye meteorite, found in the Kurgan region in 1983, are presented. It has been found that that the meteorite’s matter is composed of olivine (chrysolite), orthopyroxene (bronzite), clinopyroxene (augite), maskelynite, chromite, ilmenite, metals Fe and Ni (kamasite, taenite), sulfides (troilite, pentlandite), chlorapatite, and merrillite. Augite, taenite, pentlandite, and merrillite were identified in the Ozernoye meteorite for the first time. The chemical compositions are given for all these minerals. The meteorite itself is an ordinary chondrite stone belonging to petrological type L5.     

The magnetic-field structure in a stationary accretion disk

The magnetic-field structure in regions of stationary, planar accretion disks around active galactic nuclei where general-relativistic effects can be neglected (from 10 to 200 gravitational radii) is considered. It is assumed that the magnetic field in the outer edges of the disk, which forms in the magnetosphere of the central black hole during the creation of the relativisitic jets, corresponds to the field of a magnetic dipole perpendicular to the plane of the disk. In this case, the azimuthal field component B_φ in the disk arises due to the presence of the radial field B_ρ and the azimuthal velocity component U_φ. The value of the magnetic field at the inner radius of the disk is taken to correspond to the solution of the induction equation in a diffusion approximation. Numerical solutions of the induction equation are given for a number of cases.     

Alkaline basaltic volcanism of the Sea of Japan and the Philippine Sea: Similar and distinct geochemical and genetic features

The results of study of the deep sources of volcanic rocks from the Sea of Japan and the Philippine Sea with continental and oceanic basements, respectively, are presented. This problem is considered with the example of alkaline volcanic rocks of the Middle Miocene to Pliocene complex of the Sea of Japan and the Eocene–Oligocene Urdaneta Plateau of the Philippine Sea. The rocks have a similar geochemistry typical of OIBs, which indicates their deep (plume) origin. The presence of the Oligocene calc-alkaline volcanic rocks, which were formed prior to the marginal sea volcanism in the Sea of Japan, however, is the main difference in volcanism of the Sea of Japan from that of the Urdaneta Plateau, and this is explained by the different basements of these seas.     

Generation of the low-frequency branch of acoustic emission in affected rocks

As follows from data analysis of physical modeling, the reaction of acoustic background oscillations to an external impact is well-defined under triaxial loading of a dry sandstone core in the low-frequency range (1–100 Hz). This phenomenon is explained by the generation of a low-frequency constituent of acoustic emission. A high correlation of oscillation dynamics (Klimontovich S entropy) is observed at frequencies of tens of hertz and tens of kilohertz in the absence of such a correlation in the intermediate frequency range; a synchronous increase in the oscillation level is also observed at low and high frequencies.     

Correlation dependences of electromagnetic and deformation parameters

In-situ monitoring observations are carried out, and correlation analysis aimed at estimating the dependences between the electromagnetic parameters (variations of apparent resistivity, the impedance phase, components of the impedance tensor, and deformations of the daylight surface on the territory of the Bishkek geodynamic polygon) is performed. A new approach to the explanation of the physical mechanism forming variations in electrical conductivity of the medium is proposed on this basis.     

Authigenic mineral formation in fluid permeability zones in the West Siberia Permafrost

Basic chemical and mineralogical anomalies in permafrost caused by hydrocarbon migration are considered. Direct evidence for bacterial oxidation of light hydrocarbons, primarily methane, were first obtained in fluid permeability zones in the permafrost as a stepwise formation of authigenic minerals such as iron sulfides and oxides, carbonates, silicates, and gypsum.     

The electron density in clouds of turbulent interstellar plasma

The dependence of the emission measure on the dispersion measure due to the Galactic background has been derived for 120 directions in the Galaxy. This analysis has yielded the mean electron density, effective thickness of the electron layer, and the volume filling factor of the clouds of ionized gas along the line of sight. The pulsar J1745?2900, which lies in a direction close to the direction toward the center of the Galaxy, is located at least 100 pc closer to the observer than the source Sgr A* along the line of sight. The scatter-broadened angular size of J1745?2900 is determined by the turbulent medium in the Sagittarius Arm.     

A study of the region of massive star formation L379IRS1 in radio lines of methanol and other molecules

The results of spectral observations of the region of massive star formation L379IRS1 (IRAS18265–1517) are presented. The observations were carried out with the 30-m Pico Veleta radio telescope (Spain) at seven frequencies in the 1-mm, 2-mm, and 3-mm wavelength bands. Lines of 24 molecules were detected, from simple diatomic or triatomic species to complex eight- or nine-atom compounds such as CH₃OCHO or CH₃OCH₃. Rotation diagrams constructed from methanol andmethyl cyanide lines were used to determine the temperature of the quiescent gas in this region, which is about 40–50 K. In addition to this warm gas, there is a hot component that is revealed through high-energy lines of methanol and methyl cyanide, molecular lines arising in hot regions, and the presence of H₂O masers and Class II methanol masers at 6.7 GHz, which are also related to hot gas. One of the hot regions is probably a compact hot core, which is located near the southern submillimeter peak and is related to a group of methanol masers at 6.7 GHz. High-excitation lines at other positions may be associated with other hot cores or hot post-shock gas in the lobes of bipolar outflows. The rotation diagrams can be use to determine the column densities and abundances of methanol (10^?9) and methyl cyanide (about 10^?11) in the quiescent gas. The column densities of A- and E-methanol in L379IRS1 are essentually the same. The column densities of other observedmolecules were calculated assuming that the ratios of the molecular level abundances correspond to a temperature of 40 K. The molecular composition of the quiescent gas is close to that in another region of massive star formation, DR21(OH). The only appreciable difference is that the column density of SO₂ in L379IRS1 is at least a factor of 20 lower than the value in DR21(OH). The SO₂/CS and SO₂/OCS abundance ratios, which can be used as chemical clocks, are lower in L379IRS1 than in DR21(OH), suggesting that L379IRS1 is probably younger than DR21(OH).