Lava trees and tree molds (“cannon stones”) of Mt. Etna

Unique volcanic structures, known in the literature as “lava trees” and “tree molds”, have formed at several sites on Mt. Etna volcano (northeastern Sicily, Italy). They form when a fluid lava flow runs over a tree, wraps around it and, while the wood burns off, solidifies forming a hollow cast of the tree. The inhabitants of the Etna area call these formations “pietre cannone” (“cannon stones”) because of their cylindrical shape. The first documentation of lava trees is from Hawaii, but the first eye-witnessed accounts of their formation are, to our knowledge, from Etna’s 1865 eruption. Although many of the literature examples of lava trees and tree molds formed in pahoehoe, many of those reported in this work formed in a’a. The sites where we have found the lava tree molds are located within the territory of the Etna Regional Park; most occur next to walking trails and have a high potential for geotourism.     

East-west crustal structure and “down-bowing” Moho under the northern Tibet revealed by wide-angle seismic profile

We recognized 6 sets of reflecting P- and S-wave events from Moho and other interfaces within the crust, respectively, with the wide-angle seismic data acquired from 510 km-long Selincuo-Ya’anduo profile in the northern Tibet, fitted the observed events with forward modeling, and interpreted crustal structure of P- and S-wave velocities and Poisson’s ratio under the profile. The results demonstrate that the crustal structure between Yarlungzangbo and Bangong-Nujiang sutures changes abruptly, and the crust is the thickest at the middle part of the profile with thickness of 80 km or more. The “down-bowing” Moho is the striking feature for the crustal variation along the west-east direction. The Moho uplifts with steps, and the uplifting rate westward is greater than that eastward. The heterogeneity of P- and S-wave velocities exists both vertically and horizontally, and one lower velocity layer (LVL) exists with the depth range of 27–34 km and the thickness range of 5–7 km. For the upper crust, Poisson’s ratio is the lowest at the middle part of the profile; for the lower crust, the Poisson’s ratio at the east segment is lower than that at west segment, which means that the crustal rigidity for the upper crust is different from the lower crust, and the lower crust under the east segment of the profile is more ductile. We infer that the substance in the lower crust endured eastward flow along with the collision between Eurasian and Indian plates, and the “down-bowing” Moho is attributable to the multi-phase E-W tectonic processes.     

Modeling of the marine environmental pollution by petroleum hydrocarbons and their biotransformation in Tatar Strait waters

A hydroecological model is used for simultaneous studying water pollution processes by petroleum hydrocarbons and their decay under the oceanographic conditions of Tatar Strait. The model calculations were based on long-term averaged observational data on interannual variations of water temperature, light intensity, and transparency. Some oceanographic characteristics of the strait were reconstructed with the help of GIS “Sakhalin Shelf.” The strait’s water area was divided into three regions, and water exchange between them and the neighboring regions of the Sea of Japan was estimated by a hydrodynamic model. The results of the study made it possible to assess interannual variations in the concentrations and inner fluxes of petroleum hydrocarbons, oil-oxidizing bacteria biomasses, and the characteristics of their oxidation activity.     

Turbulence in vegetated flows: Volume-average analysis and modelling aspects

Two approaches for the modelling of turbulence in vegetated flows have been developed in the past. The “microscopic” approach which is straightforward but limited to simple cases and the “macroscopic” approach which is based on Volume Average Theory (VAT). In this study, aspects of Volume-Average (VA) analysis and modelling are investigated for turbulent vegetated flow using computed three-dimensional results from the solution of the Reynolds-Averaged Navier-Stokes (RANS) equations around a representative vegetal element. In particular (a) the VA transport equations for k and ε, based on VAT, are properly derived, (b) the Boussinesq hypothesis for the VA quantities, employed in 〈k〉-〈ε〉 turbulence models is tested, and (c) the values of the coefficients used in such turbulence models are assessed in comparison with those used in the classical turbulence models.     

A bi-directional gap model for simulating the directional thermal radiance of row crops

Row crops are a kind of typical vegetation canopy between discrete canopy and continuous canopy. Kimes et al. studied the directional thermal radiation of row crops using the geometrical optical model, which simplified row structure as “box” and neglected the gap among foliage and did not consider the emissivity effects. In this work we take account of the gaps along illumination and viewing directions and propose a bi-direction gap model on the basis of the idea of gap probability of discrete vegetation canopy introduced by “Li-Strahler” and inter-correlation of continuous vegetation developed by Kuusk. It can be used to explain “hot spot” effects in thermal infrared region. The gap model has been validated by field experiment on winter wheat planted in shape of rows and results show that the gap model is better than Kimes’ model in describing the directionality of thermal infrared emission for row crops.     

Bathing water quality monitoring of Varna Black Sea coastal zone,Bulgaria

Physicochemical and microbiological characteristics of the bathing waters in Varna’s Black Sea coastal area were investigated during year 2007 at 23 monitoring stations. Most of the determined physicochemical parameters—pH, mineral oils, surface active substances, phenols, dissolved oxygen, nutrients and microbiological parameters—“Total coliforms”, “Faecal coliforms”, “Faecal streptococci” were in compliance with the guidline’ limits and exhibited good water quality. Ammonium and phosphate’s pollution above the limits was determined at the South beach, Officers beach and Central beach situated in Varna’s central bathing zone. For the period of 13.08 to 24.10.2007—70% of the South beach samples analyzed for NH₄⁺ exceeded the limits 60 times and the concentrations of PO₄³⁻ exceeded the limits 17.5 times. Some deviations from the guidline’ limits regarding the microbiology were exhibited at the same beaches. A conclusion is made that the area of study is not yet seriously threatened, in spite of the rapid recreation during the last years.     

2D equivalent linear site effect simulation: example applications to two deep valleys

In the framework of the Sismovalp European project, an equivalent linear 2D code was developed to compute the response of a valley to SH waves, using the discrete wave-number method proposed by Aki and Larner (Aki K, Larner KL (1970) J Geophys Res 75:5). To overcome the frequency upper bound limitation, the Aki and Larner’s method is combined with a one-dimensional computation using a classical multi-layer method (Aki K, Richards PG (1980) Quantitative Seismology: Theory and Methods, vols. 1 & 2. W.H. Freeman & Co, San Francisco). The so-called “Aki–Larner extended method” is associated to an iterative algorithm, as proposed by Seed and Idriss (Seed HB, Idriss IM (1969) Report No. EERC 70–10, Earthquake Research Center, University of California, Berkeley, California) which accounts for the modulus and damping degradation using a linear visco-elastic model. A comparison of the results in the linear and the equivalent linear cases, for a magnitude 6.0 earthquake, shows that the account for the equivalent linear behaviour of the soil significantly reduces the amplification level, especially at frequencies higher than the fundamental resonance frequency of the site. In the case of site effects or microzonation studies devoted to produce design spectra for engineering structures, this can have a major impact on the associated results and costs, depending on the frequency of interest for the considered structure. As a first application of the developed technique, 2D equivalent linear Aki–Larner computations are used to perform the seismic microzonation study of the upper Rhone valley, in the Visp area (Switzerland), a typical 2D alpine valley. These investigations made it possible to determine site specific spectra, associated with different zones, to be used instead of the code spectra that do not take into account the local 2D amplification.     

Properties of wave velocity for two types of granitoids at high pressure and temperature and their geological meaning

The wave velocity for two types of granitoids was measured using the analytic method of full-wave vibration at high pressure and high temperature. The laws of velocity changes for them differ with the pressure boost and temperature rise, and the velocity change of S-type is more violent than that of I-type. The “softening point” of compressional wave velocity (V μ) is also revealed during the measurement for two types of granitoids imitating the pressure and temperature at a certain depth. But the depth of “softening”, V_p after “softening” and the percentage of V_p’s drop around the “sofrening point” for two types of granitoids are obviously different. The depth of “softening” is 15 km approximately and V_p after “softening” is 5.62 km/s for S-type granitoid. But for I-type granitoid the depth of “softening” is 26 km approximately and V_p after “softening” is 6. 08 km/s. Through careful analysis of rock slices after the experiment, it was found that the “softening” of elastic-wave velocity is caused by the partial melting of granite. Combined with the results of geophysical prospecting, these results suggest that the low-velocity layers developing in the interior of Earth crust are related to thc partial melting of different types of granitoids. The formation of the low-velocity layer in the upper-middle Earth crust is closely related to the development of S-type granitoid, but that in the lower Earth crust is closely related to the development of I-type granitoid.     

Pioneer organisms after F-F mass extinction in Dushan region, Guizhou Province, and their significance in establishing new ecosystem

After bio-mass extinction, the ecosystems in most areas were damaged seriously and may become an “ecologically barren area” lacking or even without ecosystems. To know what the pioneer organisms would be and their development, and to trace the es- tablishment process of the ecosystems are of great importance for the study of the biological evolution and recovery in aftermath. As one of the “big five” mass extinctions in the geological history, the Late Devonian Frasnian-Famennian (F-F) e…     

Study on the pattern and mode of vertical crustal deformation during the seismogenic process of intraplate strong earthquakes

Ｓｔｕｄｙｏｎｔｈｅｐａｔｔｅｒｎａｎｄｍｏｄｅｏｆｖｅｒｔｉｃａｌｃｒｕｓｔａｌｄｅｆｏｒｍａｔｉｏｎｄｕｒｉｎｇｔｈｅｓｅｉｓｍｏｇｅｎｉｃｐｒｏｃｅｓｓｏｆｉｎｔｒａｐｌａｔｅｓｔｒｏｎｇｅａｒｔｈｑｕａｋｅｓ杨国华，桂昆长，巩曰沐，杨春花，韩...     

Evolution of radiative sand ridge field of the South Yellow Sea and its sedimentary characteristics

A sand ridge field of 22 470 km² consists of fine sands and silts originally from the old Changjiang River sediment during the late Pleistocene period. Late Holocene sand stratum with its well-preserved larmnary bedding of more clay particles reflects the influence from the Yellow River. There are three genetic types of morphology of sand ridge field as follows: (i) reformed alluvial sandy bodies and old river valleys, located in the central and southern parts, formed from the end of Pleistocene to the present. (ii) Radiative current ridges and patrimonal valley type, located in the northeastern part, formed during the early or middle Holocene time. (iii) Eroded-depositional sandy bodies in the north and outer parts, and erosional trough in the north formed since the middle Holocene transgression. The sand ridge field has a periodic nature of developing processes: the period of sediment accumulation by rivers during cold epoch with low sea level and the period of erosional formation by tidal currents during warm epoch of transgression. The river-sea interactive process in the area is closely related to the climate change; the rising and falling of the sea level is the detonating agent of the coast zone land-sea dynamic interactive processes. They can be summarized as “transgression-dynamic-sedimentation” processes. Project supported by the National Natural Science Foundation of China (Grant No. 49236120). Pmject codmg: SCIEL 21198103.     

Suspended sediment transport in the German Wadden Sea—seasonal variations and extreme events

The German Wadden Sea (southern North Sea) sediments are composed of both cohesive and non-cohesive deposits. The spatial distribution patterns are mainly driven by wind-induced waves and tidal currents. Transport intensity and duration depend on the hydrodynamic conditions, which vary over time. In this paper, the transport of suspended sediment was investigated on seasonal, tidal and hourly time scales in the back-barrier system of Spiekeroog Island. Long- and short-term data of fair weather periods and two storm events were investigated based on stationary and mobile measurements of currents and waves by Acoustic Doppler Current Profiler (ADCP), in situ particle size and suspended sediment concentration (SSC) measurements by laser in situ scattering and transmissometry (LISST) as well as wind records. The ADCP backscatter intensities were calibrated by means of LISST volume concentration data in order to quantify longer term SSCs and fluxes in the back-barrier system. Values up to 120 mg l⁻¹ were recorded, but concentrations more commonly were below 60 mg l⁻¹. The long-term results confirm former observations of a balanced budget during low-energy (fair weather) conditions in the study area. In general, SSCs were higher during spring tides than during neap tides. The data also clearly show the remobilisation of sediment by tidal current entrainment. The records include two severe storm events, “Britta” (1st November 2006) and “Kyrill” (18th January 2007). The data reveal very complex temporal flow and transport patterns. During both storm events, the export of material was mainly controlled by the interaction of wind, waves and tidal phase. The typical ebb-dominance occurring during fair-weather conditions was temporarily neutralised and even reversed to a flood-dominated situation. During “Kyrill”, the wind and high-waves setup in conjunction with the tidal phase was even able to compress the duration of two successive ebb cycles by over 70%. Although SSCs increased during both storms and higher turbulence lifted particle clouds upwards, an export of suspended matter towards the North Sea was only observed under the conditions taking place during “Britta”. Such fluxes, however, are currently still difficult to quantify because the backscatter intensity during high energy events includes a substantial amount of noise produced by the high turbulence, especially near the water surface.     

On the seismic regime network method

In this paper, based on the previous study of practical use of seismic regime windows and seismic regime belts, the problem of establishing a “seismic regime network” consisting of “windows” and “belts” is further posed and discussed according to the observed fact that many “windows” and “belts” make responses to one earthquake. For the convenience of usage, the “seismic regime network” is divided into two classes, the first class and the second one. The former can be used in tendency prediction for long-term seismic activity in a large area, the latter used in short-term prediction in a small area. In this paper, after briefly discussing the physical significance of “seismic regime network”, it is pointed out that this simple and easily used method can be used to observe and extract seismic precursory information from a large area before a great earthquake, thus it can provide a reliable basis for the analysis and judgement of seismic regime tendency in time and space. No doult, this method is of certain practical significance. The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,13, 161–169, 1991. The English version of this paper is improved by Prof. Shaoxie Xu.     

Die Matrix der Fische XIV. Elektronenmikroskopische Untersuchung von Fischschuppen

Summary The investigation with an electron-microscope of the scales of the fresh water fish,Leuciscus rutilus L., showed that their ventral “smooth” surface scems to be formed like a corrugated plate with a distance between the ridges of 1–2 μ. The dorsal “rough” side of the scales shows a very fine roughness. It is interrupted by pointed combs of the same structure in a regular distance of 16–27 μ. The thickness of these combs is of about 1 μ at their base, their height of about 5–10 μ. It seems probable that the surface of scales is partially covered with laminas of hyalodentine or guanine.

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13. Mitteilung siehe diese Zeitschrift,13, 29–30 (1951).     

Model identification for hydrological forecasting under uncertainty

Methods for the identification of models for hydrological forecasting have to consider the specific nature of these models and the uncertainties present in the modeling process. Current approaches fail to fully incorporate these two aspects. In this paper we review the nature of hydrological models and the consequences of this nature for the task of model identification. We then continue to discuss the history (“The need for more POWER‘’), the current state (“Learning from other fields”) and the future (“Towards a general framework”) of model identification. The discussion closes with a list of desirable features for an identification framework under uncertainty and open research questions in need of answers before such a framework can be implemented.     

Hyperconcentrated flows as influenced by coupled wind-water processes

Hyperconcentrated flow is a natural phenomenon, which is widely observed on the Loess Plateau of China[1,2]. So far, much research has been done with hyperconcentrated flows in China[1―7], although hy-perconcentrated flows are also observed in many riv-ers in other countries[8―10]. In the monograph edited by Chien[11], hyperconcnetrated flows were studied in depth, involving the physical properties, resistance, sediment-carry behavior and channel-forming pro- cesses. Wang and Chien el al.[…     

Making and Breaking of a Continent: Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics

The African continent inherits a long history of continental accretion and breakup. The stage of “making” a continent goes back to the Archean, when the first continental masses formed cratons which mostly remained stable ever since. Subsequent collision of weaker continental masses was followed by several extension and compression episodes that resulted in the formation of super-continents. After the assemblage of Gondwana, a period of predominantly “breaking” , i.e., the breakup of super-continents, took over. The modern-day African continent exhibits different types of margins; continental rifting occurs side by side with recent collision. Since the late 1960s, magnetotelluric (MT) experiments have played an important role in studies of the electrical conductivity structure of Africa. The early results significantly shaped the MT community’s understanding of continental-scale conductivity belts and basic characteristics of cratons and mobile belts on both crustal and lithospheric mantle scales for some decades. Modern MT studies in Africa have generally supported earlier results with high resistivities observed on cratons and low resistivities observed across mobile belts. Advances in instrumentation, data processing and interpretation resulted in higher-resolution images of the lithosphere, which in consequence induce an improved understanding of tectonic processes and geological prerequisites for the occurrence of natural resources. The high electrical conductivity of mobile belts and their relation to reactivated fault and detachment zones were often interpreted to characterize mobile belts as tectonic weak zones, which can accommodate stress and constitute zones along which continents can break. Recent breaking of the African continent can be studied on land across the East African rift; however, the lack of amphibian MT experiments across today’s margins does not allow for good resolution of remnants of continental breakup processes. Naturally, the regions and the focus of the MT studies in Africa are diverse, but they all contribute to the story of making and breaking a continent.     

Rapid injection of particles and gas into non-fluidized granular material, and some volcanological implications

In diatremes and other volcanic vents, steep bodies of volcaniclastic material having differing properties (particle size distribution, proportion of lithic fragments, etc.) from those of the surrounding vent-filling volcaniclastic material are often found. It has been proposed that cylindrical or cone-shaped bodies result from the passage of “debris jets” generated after phreatomagmatic explosions or other discrete subterranean bursts. To learn more about such phenomena, we model experimentally the injection of gas-particulate dispersions through other particles. Analogue materials (glass beads or sand) and a finite amount of compressed air are used in the laboratory. The gas is made available by rapidly opening a valve—therefore the injection of gas and coloured particles into a granular host is a brief (<1 s), discrete event, comparable to what occurs in nature following subterranean explosions. The injection assumes a bubble shape while expanding and propagating upwards. In reaction, the upper part of the clastic host moves upward and outward above the ‘bubble’, forming a ‘dome’. The doming effect is much more pronounced for shallow injection depths (thin hosts), with dome angles reaching more than 45°. Significant surface doming is also observed for some full-scale subterranean blasts (e.g. buried nuclear explosions), so it is not an artefact of our setup. What happens next in the experiments depends on the depth of injection and the nature of the host material. With shallow injection into a permeable host (glass beads), the compressed air in the “bubble’ is able to diffuse rapidly through the roof. Meanwhile the coloured beads sediment into the transient cavity, which is also closing laterally because of inward-directed granular flow of the host. Depending on the initial gas pressure in the reservoir, the two-phase flow can “erupt” or not; non-erupting injections produce cylindrical bodies of coloured beads whereas erupting runs produce flaring upward or conical deposits. Changing the particle size of the host glass beads does not have a large effect under the size range investigated (100–200 to 300–400 μm). Doubling the host thickness (injection depth) requires a doubling of the initial gas pressure to produce similar phenomena. Such injections—whether erupting or wholly subterranean—provide a compelling explanation for the origin and characteristics of multiple cross-cutting bodies that have been documented for diatreme and other vent deposits.