Detached eclipsing binaries: analysis of BD–00° 3357

Detached eclipsing binaries constitute potential accurate distance tracers. They are also useful as the test bench of stellar evolution. In BD–00° 3357 eclipses are partial and its orbital period is 1.^d4. Our combined spectroscopic and photometric solution yields secure parameters of this system. The model of the star was obtained using the Wilson‐Devinney method. As result we obtained a semi major axis of 7.65 R_⊙ and a mass ratio of 0.78. The derived masses and radii are M ₁ = 1.73 M_⊙,M ₂ = 1.34 M_⊙R ₁ = 1.78 R_⊙, R ₂ = 1.32 R_⊙, respectively. These values correspond to the slightly evolved F0 and F6.5 components, both slightly less than 1Gyr old. The distance of the star was estimated to be 310 ± 60 pc, and the corresponding photometric parallax is 3.24 ± 0.74 mas. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

2MASS J01074282+4845188: A new nova-like cataclysmic star with a deep eclipse

We present V RI photometry and low-resolution spectroscopy of the object 2MASS J01074282+4845188. The V-shape of the eclipse, the phase variability of the colour indices as well as the presence of a pre-eclipse hump, standstill and flickering allow us to conclude that it is a nova-like cataclysmic star. This is supported by the observed broad emission Hα line. Its single profile with a relatively narrow FWHM but large FWZI is typical for a nova-like variable of SW Sex subtype. The observed deep eclipses make the newly discovered cataclysmic star 2MASS J01074282+4845188 an interesting object for future investigation.     

Simple procedure for quantification of the gravitational stress field in fractured hard rock massifs

In this paper, a quantitative procedure for evaluating the gravitational stress field in a hard rock massif is presented, using only a geological hammer and compass. Using the orientation of the fracture planes and their statistical distribution, a method for calculating of the tendency of the fractures to reactivate under gravitational load is proposed, based on Coulomb failure criterion. The method is applicable for assessing the most stable layout of the underground excavations and for evaluating the geometry of the stress field at a point during the initial stage of rock failure.     

Search for Traces of Strong Ancient Earthquakes in the Western Caucasus: Archeoseismological Studies in Ancient Gorgippia

Izvestiya, Atmospheric and Oceanic Physics - The ancient city of Gorgippia is surrounded by well-known (North Black Sea, Kerch, and South Azov) seismogenic zones, all of which are submarine, and...     

Postseismic deformation at El Asnam (Algeria) in the seismotectonic context of northwestern Algeria

We use a combination of seismicity. tectonic features, focal mechanisms, seismic strain and postseismic movement to study the western part of North Algeria, the El Asnam region and its surrounding area in particular. A seismotectonic map of this part of Algeria, delimited by the Mediterranean Sea in the north and the Tellian mountains in the south, was built from available geological and seismological data. An examination of this map shows that the most significant earthquakes are concentrated along tectonic features and quaternary basins elongated in an east-west direction, suggesting NNW-SSE compressional movements. During the large El Asnam earthquake of 1980 October 10, M _w= 7.1, vertical movement was measured along a 40 km northeast-southwest thrust fault. These movements were determined geodetically in 1981 with reference to a basic network previously measured in 1976. In order to control postseismic movement and to ensure the monitoring of the seismic area, a dense geodetic network has been regularly measured since 1986, both in planemetry and altimetry. The results of the altimetric remeasurements show significant vertical movements. The elevation changes of the benchmarks have been deduced from precise levelling measurements: a remarkable uplift (5.1 ± 1.9 mm yr⁻¹) of the northwestern block, during the 1986-91 period has been observed, whereas the southeastern block is seen to be relatively stable. The Sar El Marouf anticline, situated along the central segment of the El Asnam surface breaks, appears to be growing with a maximum postseismic slip rate of (9.6 ± 1.4 mm yr⁻¹). The mean uplift rates computed for the northwestern block support the view that the 1954 earthquake did not occur on the same reverse fault as the 1980 event.     

Mud Volcanoes and Dome-Like Structures at the Eastern Mediterranean Ridge

Marine Geophysical Research - The Mediterranean Ridge is interpreted as a large accretionary complex, which originated due to the northern subduction of the African lithosphere below the Eurasian...     

Did postglacial catastrophic flooding trigger massive changes in the Black Sea gas hydrate reservoir?

After the Last Glacial Maximum, the semi-land-locked Black Sea basin was flooded by warm water from the Mediterranean Sea. This major sea level rise and change of physical water properties had a large impact on the gas hydrate reservoir in the sediments below. Modelling of the regional response of the gas hydrate stability zone (GHSZ) to the Black Sea flooding 7100 years ago shows that a strong effect of near-bottom temperature increase pushes the gas hydrate reservoir to a large shrinking of 15–62% that may release up to 1.1–4.6 Gt of methane. This catastrophic scenario is, however, delayed because of the transient nature of the heat wave propagation. The large-scale reduction of the GHSZ is only to take place within the next thousand years. At present, widespread hydrate dissociation is only expected to occur where there is a minimum water depth for hydrate stability.