Guidelines for the good practice of surface wave analysis: a product of the InterPACIFIC project

Surface wave methods gained in the past decades a primary role in many seismic projects. Specifically, they are often used to retrieve a 1D shear wave velocity model or to estimate the V_S,30 at a site. The complexity of the interpretation process and the variety of possible approaches to surface wave analysis make it very hard to set a fixed standard to assure quality and reliability of the results. The present guidelines provide practical information on the acquisition and analysis of surface wave data by giving some basic principles and specific suggestions related to the most common situations. They are primarily targeted to non-expert users approaching surface wave testing, but can be useful to specialists in the field as a general reference. The guidelines are based on the experience gained within the InterPACIFIC project and on the expertise of the participants in acquisition and analysis of surface wave data.     

黄龙与黄石钙华微生物沉积作用比较研究

本文通过调查黄龙风景区水体的环境地质特征与微生物群落结构及多样性,并与黄石公园对比分析,探讨了两种特殊地理环境下的微生物群落结构和多样性及其对钙华沉积的影响.结果表明:黄龙沟泉水属于地下冷泉,且景区内覆盖着大量植被,水体中有大量藻类和细菌;黄石公园猛犸象温泉区泉水属于地下热泉,植被覆盖率很低,泉水中微生物多为嗜热菌,藻...     

Thermal springs,fumaroles and gas vents of continental Yemen: Their relation with active tectonics,regional hydrology and the country’s geothermal potential

Most thermal springs of continental Yemen (about 65 emergences at 48 sampling sites) and a couple of fumaroles and boiling water pools have been sampled and analyzed for chemical and isotopic composition in the liquid phase and the associated free-gas phase. Whatever the emergence, all the water discharges have an isotopic signature of meteoric origin. Springs seeping out from high altitudes in the central volcanic plateau show a prevalent Na–HCO₃-composition, clearly affected by an anomalous flux of deep CO₂ deriving from active hydrothermal systems located in the Jurassic Amran Group limestone sequence and/or the Cretaceous Tawilah Group, likely underlying the 2000–3000 m thick volcanic suite. At lower elevations, CO₂ also affects the composition of some springs emerging at the borders of the central volcanic plateau.     

Numerical simulation of internal boundary-layer development and comparison with atmospheric data

A finite-volume numerical model is employed to investigate the adaptation of the atmospheric boundary layer to a change in the underlying surface roughness, such as that existing in the transition from land to the free surface of a water body. Numerical results are validated by comparison with neutral stratification atmospheric data and compared with the internal boundary-layer (IBL) heights computed using a number of existing empirical formulae. The numerical analysis allows an extension of the fetch range in which the existing formulae, calibrated only by comparison with short fetch data, may be applied. An argument is offered that the spatial variability of the water surface roughness should be also taken into account for the IBL development over the surface of a water body.     

Temporal Variability of Major and Trace Element Concentrations in the Groundwaters of Mt. Etna (Italy): Effects of Transient Input of Magmatic Fluids Highlighted by Means of Cluster Analysis

Data for major, minor and trace elements in groundwaters from Mt. Etna volcano collected in 1994, 1995 and 1997 were analyzed using Cluster Analysis (CA). Two groups of sampling sites were identified (named clusters A and B), mainly on the basis of their different salinity and content of dissolved CO₂. The highest levels of both of these parameters were observed in the sites of cluster A, located in the lower south-western and central eastern flanks of the volcano. For both of the statistical groups CA was repeated, taking into account the mean values of each parameter in time, and the results allowed us to recognize four distinct groups of parameters for each group of sites on the basis of their temporal patterns. Four different types of temporal patterns were recognized: concave, convex, increasing, decreasing. The observed changes were basically interpreted as a result of the different response of dissolved chemical elements to changes in the aqueous environment and/or in their solubility/mobility in water due to different rates of input of magmatic gases to Etna’s aquifers. The main changes occurred in 1995, when Etna’s volcanic activity resumed after a two-year period of rest. The temporal changes of the majority of the studied parameters (water temperature, water conductivity, Eh, pH, Al, Mg, B, Ca, Cl⁻, Hg, Mn, Mo, Na, Ni, Se, Si, Sr, Cr Zn and pCO₂) were not cluster-dependent, therefore they were not apparently affected by differences in water salinity between the two groups of sampling sites. A limited number of parameters (Ti, K, Li, HCO₃⁻, As, Fe, SO₄²⁻, Cu and V), however, manifested different behaviors, depending on the cluster of sites to which they belonged, thus suggesting their apparent dependency on water salinity.     

Styles of tectonic inversion within syn-orogenic basins: examples from the Central Apennines, Italy

The geometry of several thrust-related folds in the Central Apennines of Italy results from a switch in deformation regime, from extension to contraction. This switch in tectonic regime occurred during the deposition of syn-orogenic sediments, and the emplacement and migration of the thrust belt–foredeep system towards the foreland in Neogene time. The styles of positive tectonic inversion result from normal faults that were steepened, rotated and truncated by thrusts, with local development of minor folds due to buttressing. Normal fault-controlled escarpments are also locally preserved in the forelimbs and backlimbs of thrust-related anticlines. The location and amplitudes of contractional structures across the belt reflects the distribution of pre-thrusting normal faults within precursor syn-orogenic basins, a result that may improve our understanding of the evolution of Apennine, as well as other thrust belt–foredeep systems.     

Electron density and temperature measurements, and abundance anomalies in the solar atmosphere

Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect (the abundance enhancement of elements with first ionization potential < 10 eV in the corona with respect to photospheric values) with height above an active region observed at the solar limb, with emphasis on the so-called transition region lines.     

Turbulence in the Stable Boundary Layer at Higher Richardson Numbers

We present some algebraic and numerical simulations of the stable boundary layer. We also discuss the problem of the existence of a critical Richardson number (Ri), beyond which the turbulence is suppressed. We compare the results of a second-order algebraic model with those of a third-order numerical model and, to this purpose, numerical simulations of a wind-tunnel flow, which is characterized by various Richardson numbers, were performed. As far as the second-order model is concerned, solutions, for the Richardson number greater than any critical value, can be obtained by modifying the time scales of the second-order equation pressure correlation terms in order to account for a buoyancy damping factor. We show that using a third-order model allows the same results (no critical Richardson number) to be obtained without modifications to the time scales. It is suggested that the non-locality, accounted for by the third-order moments, could allow the turbulence to persist also for Ri > 1.