Updating default depths in the ISC bulletin

The International Seismological Centre (ISC) publishes the definitive global bulletin of earthquake locations. In the ISC bulletin, we aim to obtain a free depth, but often this is not possible. Subsequently, the first option is to obtain a depth derived from depth phases. If depth phases are not available, we then use the reported depth from a reputable local agency. Finally, as a last resort, we set a default depth.In the past, common depths of 10, 33, or multiples of 50 km have been assigned. Assigning a more meaningful default depth, specific to a seismic region will increase the consistency of earthquake locations within the ISC bulletin and allow the ISC to publish better positions and magnitude estimates. It will also improve the association of reported secondary arrivals to corresponding seismic events.We aim to produce a global set of default depths, based on a typical depth for each area, from well-constrained events in the ISC bulletin or where depth could be constrained using a consistent set of depth phase arrivals provided by a number of different reporters.In certain areas, we must resort to using other assumptions. For these cases, we use a global crustal model (Crust2.0) to set default depths to half the thickness of the crust.     

Thermochronological insights into the structural contact between the Tian Shan and Pamirs,Tajikistan

Multi‐method thermochronology along the Vakhsh‐Surkhob fault zone reveals the thermotectonic history of the South Tian Shan–Pamirs boundary. Apatite U/Pb analyses yield a consistent age of 251 ± 2 Ma, corresponding to cooling below ~550–350°C, related to the final closure of the Palaeo‐Asian Ocean and contemporaneous magmatism in the South Tian Shan. Zircon (U–Th–Sm)/He ages constrain cooling below ~180°C to the end of the Triassic (~200 Ma), likely related either to deformation induced by the Qiangtang collision or to the closure of the Rushan Ocean. Apatite fission track thermochronology reveals two low‐temperature (<120°C) thermal events at ~25 Ma and ~10 Ma, which may be correlated with tectonic activity at the distant southern Eurasian margin. The late Miocene cooling is confirmed by apatite (U–Th–Sm)/He data and marks the onset of mountain building within the South Tian Shan that is ongoing today.     

A modern analogue of the Pleistocene steppe‐tundra ecosystem in southern Siberia

Steppe‐tundra is considered to have been a dominant ecosystem across northern Eurasia during the Last Glacial Maximum. As the fossil record is insufficient for understanding the ecology of this vanished ecosystem, modern analogues have been sought, especially in Beringia. However, Beringian ecosystems are probably not the best analogues for more southern variants of the full‐glacial steppe‐tundra because they lack many plant and animal species of temperate steppes found in the full‐glacial fossil record from various areas of Europe and Siberia. We present new data on flora, land snails and mammals and characterize the ecology of a close modern analogue of the full‐glacial steppe‐tundra ecosystem in the southeastern Russian Altai Mountains, southern Siberia. The Altaian steppe‐tundra is a landscape mosaic of different habitat types including steppe, mesic and wet grasslands, shrubby tundra, riparian scrub, and patches of open woodland at moister sites. Habitat distribution, species diversity, primary productivity and nutrient content in plant biomass reflect precipitation patterns across a broader area and the topography‐dependent distribution of soil moisture across smaller landscape sections. Plant and snail species considered as glacial relicts occur in most habitats of the Altaian steppe‐tundra, but snails avoid the driest types of steppe. A diverse community of mammals, including many species typical of the full‐glacial ecosystems, also occurs there. Insights from the Altaian steppe‐tundra suggest that the full‐glacial steppe‐tundra was a heterogeneous mosaic of different habitats depending on landscape‐scale moisture gradients. Primary productivity of this habitat mosaic combined with shallow snow cover that facilitated winter grazing was sufficient to sustain rich communities of large herbivores.     

A new echiuran species Thalassema malakhovi (echiura) from New Zealand

A new echiuran Thalassema malakhovi, collected at 20 m depth off the Bay of Plenty, New Zealand, is described. The possibility of using the structure of the nephrostome for subgrouping Thalassema species is discussed. The generic diagnosis of Thalassema Pallas is given.     

Numerical simulation of seismic waves in models with anisotropic formations: coupling Virieux and Lebedev finite-difference schemes

Anisotropy is widespread in the Earth’s interior. However, there is a number of models where anisotropic formations comprise as few as 10–20?% of the volume, and this includes fractured reservoirs, thin-layered packs, etc. while the major part of the medium is isotropic. In this situation, the use of computationally intense anisotropy-oriented approaches throughout the computational domain is prodigal. So this paper presents an original advanced finite-difference algorithm based on the domain decomposition technique with individual scheme used inside subdomains. It means that the standard staggered grid scheme or the Virieux scheme is used in the main part of the model which is isotropic, while the anisotropy-oriented Lebedev scheme is utilized inside domains with anisotropic formations. Finite-difference consistency conditions at the artificial interface where the schemes are coupled are designed to make the artificial reflections as low as possible, namely, for the second-order scheme, the third order of convergence of the reflection coefficients is proved.     

Kobyashevite, Cu5(SO4)2(OH)6·4H2O, a new devilline-group mineral from the Vishnevye Mountains, South Urals, Russia

A new mineral kobyashevite, Cu₅(SO₄)₂(OH)₆·4H₂O (IMA 2011–066), was found at the Kapital’naya mine, Vishnevye Mountains, South Urals, Russia. It is a supergene mineral that occurs in cavities of a calcite-quartz vein with pyrite and chalcopyrite. Kobyashevite forms elongated crystals up to 0.2 mm typically curved or split and combined into thin crusts up to 1?×?2 mm. Kobyashevite is bluish-green to turquoise-coloured. Lustre is vitreous. Mohs hardness is 2½. Cleavage is {010} distinct. D(calc.) is 3.16 g/cm³. Kobyashevite is optically biaxial (?), α 1.602(4), β 1.666(5), γ 1.679(5), 2 V(meas.) 50(10)°. The chemical composition (wt%, electron-microprobe data) is: CuO 57.72, ZnO 0.09, FeO 0.28, SO₃ 23.52, H₂O(calc.) 18.39, total 100.00. The empirical formula, calculated based on 18 O, is: Cu_4.96Fe_0.03Zn_0.01S_2.01O_8.04(OH)_5.96·4H₂O. Kobyashevite is triclinic, $ P\overline{\,1 } $ , a 6.0731(6), b 11.0597(13), c 5.5094(6)?Å, α 102.883(9)°, β 92.348(8)°, γ 92.597(9)°, V 359.87(7)?ų, Z?=?1. Strong reflections of the X-ray powder pattern [d,Å-I(hkl)] are: 10.84–100(010); 5.399–40(020); 5.178–12(110); 3.590–16(030); 2.691–16(20–1, 040, 002), 2.653–12(04–1, 02–2), 2.583–12(2–11, 201, 2–1–1), 2.425–12(03–2, 211, 131). The crystal structure (single-crystal X-ray data, R?=?0.0399) сontains [Cu₄(SO₄)₂(OH)₆] corrugated layers linked via isolated [CuO₂(H₂O)₄] octahedra; the structural formula is CuCu₄(SO₄)₂(OH)₆·4H₂O. Kobyashevite is a devilline-group member. It is named in memory of the Russian mineralogist Yuriy Stepanovich Kobyashev (1935–2009), a specialist on mineralogy of the Urals.     

Probabilistic assessment of rogue wave occurrence in directional wave fields

Ocean Dynamics - In this study, the relation between rogue wave occurrence statistics and properties of the directional wind-wave spectrum is investigated. The study is conducted by means of the...     

Hindcast of oil-spill pollution during the Lebanon crisis in the Eastern Mediterranean, July-August 2006

MOON (Mediterranean Operational Oceanography Network http://www.moon-oceanforecasting.eu) provides near-real-time information on oil-spill detection (ocean color and SAR) and predictions [ocean forecasts (MFS and CYCOFOS) and oil-spill predictions (MEDSLIK)]. We employ this system to study the Lebanese oil-pollution crisis in summer 2006 and thus to assist regional and local decision makers in Europe, regionally and locally. The MEDSLIK oil-spill predictions obtained using CYCOFOS high-resolution ocean fields are compared with those obtained using lower-resolution MFS hydrodynamics, and both are validated against satellite observations. The predicted beached oil distributions along the Lebanese and Syrian coasts are compared with in situ observations.The oil-spill predictions are able to simulate the northward movement of the oil spill, with the CYCOFOS predictions being in better agreement with satellite observations. Among the free MEDSLIK parameters tested in the sensitivity experiments, the drift factor appears to be the most relevant to improve the quality of the results.     

Simulation of the Hurricane Dennis storm surge and considerations for vertical resolution

A high-resolution storm surge model of Apalachee Bay in the northeastern Gulf of Mexico is developed using an unstructured grid finite-volume coastal ocean model (FVCOM). The model is applied to the case of Hurricane Dennis (July 2005). This storm caused underpredicted severe flooding of the Apalachee Bay coastal area and upriver inland communities. Accurate resolution of complicated geometry of the coastal region and waterways in the model reveals processes responsible for the unanticipated high storm tide in the area. Model results are validated with available observations of the storm tide. Model experiments suggest that during Dennis, excessive flooding in the coastal zone and the town of St. Marks, located up the St. Marks River, was caused by additive effects of coincident high tides (~10–15% of the total sea-level rise) and a propagating shelf wave (~30%) that added to the locally wind-generated surge. Wave setup, the biggest uncertainty, is estimated on the basis of empirical and analytical relations. The Dennis case is then used to test the sensitivity of the model solution to vertical discretization. A suite of model experiments is performed with varying numbers of vertical sigma (σ) levels, with different distribution of σ-levels within the water column and a varying bottom drag coefficient. The major finding is that the storm surge solution is more sensitive to resolution within the velocity shear zone at mid-depths compared to resolution of the upper and bottom layer or values of the bottom drag coefficient.