The XMM‐Newton view of magnetars

Anomalous X‐ray Pulsars and Soft Gamma‐ray Repeaters are believed to be magnetars: isolated neutron stars powered by the decay of extremely high magnetic fields. We review some of the main results obtained with XMM‐Newton and discuss the prospects for future observations of this small but extremely interesting class of objects. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Setting-up local “mapping geoids” with the aid of GPS/LEV traverses. Application to the geoids of Sardinia and Calabria

The problem of fitting a pre-existing geoid on local GPS/LEV points is first taken into account, a possible way for its solution is proposed, based on techniques similar to the aerophotogrammetric absolute orientation.This approach is then used to compute themapping geoids of Sardinia and Calabria i.e. geoids with decimetric accuracy, needed for the heigthing of large scale maps. The pre-existing geoids EAGGI by Brennecke et al. (1983), and EGG2 by Denker et al (1993) are utilized, fitted on points of GPS/LEV traverses.The complete input-output data, the contour maps of both geoids, and a substantial checking on some Calabrian GPS/TRIG points of the entreprise IGM.95 are finally reported.     

Ensemble smoothing of land subsidence measurements for reservoir geomechanical characterization

Geomechanical models are often used to predict the impact on land surface of fluid withdrawal from deep reservoirs, as well as investigating measures for mitigation. The ability to accurately simulate surface displacements, however, is often impaired by limited information on the geomechanical parameters characterizing the geological formations of interest. In this study, we employ an ensemble smoother, a data assimilation algorithm, to provide improved estimates of reservoir parameters through assimilation of measurements of both horizontal and vertical surface displacement into geomechanical model results. The method leverages the demonstrated potential of remote sensing techniques developed in the last decade to provide accurate displacement data for large areas of the land surface. For evaluation purposes, the methodology is applied to the case of a disk‐shaped reservoir embedded in a homogeneous, isotropic, and linearly elastic half space, subject to a uniform change in fluid pressure. Multiple sources of uncertainty are investigated, including the radius, R, the thickness, h, and the depth, c, of the reservoir; the pore pressure change, Δp; porous medium's vertical uniaxial compressibility, c_M, and Poisson's ratio, ν, and the ratio, s, between the compressibilities of the medium during loading and unloading cycles. Results from all simulations show that the ensemble smoother has the capability to effectively reduce the uncertainty associated with those parameters to which the variability and the spatial distribution of land surface displacements are most sensitive, namely, R, c, c_M, and s. These analyses demonstrate that the estimation of these parameters values depends on the number of measurements assimilated and the error assigned to the measurement values. Copyright © 2014 John Wiley & Sons, Ltd.     

Analysis of fibrous zeolites in the volcanic deposits of the Viterbo Province,Italy

Since Etrurian age, the Viterbo Province (Central Italy) is famous for its ancient towns carved out of local ignimbrite deposits which geologically represent the sedimentation of pumice-rich, volcano-related pyroclastic flows. Almost the entire study area is geologically characterized by a thick succession of ignimbrites, tephra fallouts and lava flow deposits locally subjected to zeolitization. Among zeolites, fibrous erionite represents a well-known health hazard and so this work aims at locating and quantifying the presence of fibrous zeolites in volcanic deposits of the Viterbo area, suggesting at the same time a standard operational procedure useful in other areas showing the same possible hazard. 41 samples collected in the Viterbo area were analyzed by X-ray powder diffraction, optical and electron microscopy. Fibrous zeolites were detected in five samples and quantified in amounts ranging from 0.35 to 1.66% vol. They generally occur in tetragonal or orthorhombic prismatic habit and showed chemical composition mainly consistent with K-phillipsite. Fibrous zeolites occurred with aspect ratios (mean = 6.3), comparable or lower than those of erionite fibers reported in previous studies and mean diameters >3 μm.     

<Emphasis Type="Italic">Phragmites</Emphasis> and environmental management: A question of values

For a common, widespread, and familiar plant,Phragmites australis engenders an enormous level of scientific controversy and emotional conflict. In parts of the world,Phragmites is an important component of healthy ecosystems and an integral (if now minor) contributor to human economies. In other places it is an invading, unfriendly, and ugly weed. To some scientists and environmentalists,Phragmites is an indicator of and key factor in landscape degradation and habitat deterioration. To others, it is a valiant remnant of nature, providing a relatively rich ecology where there might otherwise be only barren and eroding ground. Our review of the literature leads us to conclude thatPhragmites is simply a biological entity. It is not inherently good or bad, since its evolution, biology, and ecology do not give it a value. The controversy overPhragmites, its role in the ecosystem, and the need for and intensity of management efforts are all artifacts of human perspectives. Effective, consistent management decisions (for either control or enhancement ofPhragmites) can only be made on the basis of site-specific scientific findings, a consideration of technologies with their needed level-of-effort, and explicit exposition of the human values driving the management options. We present a simple decision model to illustrate the interaction of these management components forPhragmites in the environment.     

A procedure to estimate the seismic hazard in an urban area: an application to Acireale (Eastern Sicily)

A “standard procedure” to characterize the seismic hazard of a given area was proposed. It is based on a multidisciplinary approach implying: (1) the knowledge of the seismic history of the area; (2) detailed geological surveys; (3)seismic noise measurements; (4) simulations of earthquake scenarios. The downtown of Acireale, a typical baroque town located on Eastern Sicily, was chosen as the “test area”. A catalog of the local seismogenic faults (able to generate earthquakes in historical times) has been compiled, as well as a seismic catalog for the effects of both local and regional earthquakes. The analysis of both catalogs allowed us to make the following conclusions: (1) the most important seismogenic faults affecting the Acireale municipality do not affect the downtown, while the related local earthquakes attenuate their energy (and intensity) in short (few km) distances; (2) the highest seismic intensity (degree X) experienced in Acireale downtown was caused by the 1693 regional earthquake; (3) over the last 140 years, the downtown has experienced the highest intensity value of VII only once, while six times the intensity was VI. On the whole, this implies a moderate seismic hazard. The estimation of the seismic hazard has been also approached by the experimental method of recording seismic noise. Measurements have been performed at seven different sites, where drills gave detailed information on the shallow subsurface geology to obtain HV (horizontal/vertical) spectral ratios. On the whole, the highest site amplification factor was moderate (about 7). A further investigation based on synthetic seismograms (and spectra) produced by simulating two given earthquake scenarios was also performed. The two scenarios are, respectively, representative of the largest expected earthquake in the area (the 1693 shock) and of a moderate (magnitude ca. 5.5) local earthquake (as the 1818 one). Moderate to strong locally expected accelerations were evidenced.     

Typical source areas of May 1998 flow-like mass movements in the Campania region, Southern Italy

Flow-like mass movements in granular materials are among the most serious natural hazards, systematically producing huge amounts of damage and numerous victims, especially when involving volcanic soils. This is the case of the events in Southern Italy in May 1998, when rainfall triggered many destructive landslides along the slopes of a carbonate massif mantled by pyroclastic soils. Due to the complexity of the occurred phenomena, a shared interpretation of their triggering stage is still not available.

As a contribution to the topic, the paper initially discusses the geological and geomorphological features of the massif combining them in three hillslopes models. The models are then associated to the hydrogeological features and anthropogenic factors in order to define six typical landslides source areas that are not casually distributed on the massif. The study subsequently focuses on the most frequent type of source areas, associated to the largest unstable soil volumes and longest run-out distances. For these source areas, the triggering mechanism is discussed, with an example of geotechnical validation being proposed for a well monitored mountain basin. The geotechnical modelling at site scale confirms the geological analyses at massif scale and provides further insights into the events, thus highlighting the potential of a multidisciplinary approach for the interpretation of very complex slope instability phenomena.     

A new approach to landslide geomorphological mapping using the Open Source software in the Olvera area (Cadiz, Spain)

This paper presents the preliminary results of a geomorphological survey of the Olvera area (Cadiz province, Betic Ranges, Spain) and the use of the Geographic Information System (GIS) Open Source (OS) software plus Database Management System (DBMS) for making available and distributing the landslide data over the Web. In the geomorphologic survey, different landforms have been identified in the area, including structural, anthropogenic, fluvial, karst, and slope forms. In particular, the majority of the slope forms are complex (from topple to rotational slides and falls), but there are also minor forms like debris flows and mudslides. To manage geomorphological data, an Open Source GIS was used, which contained the following components: QuantumGIS, System for Automated Geoscientific Analyses (SAGA), GIS and Geographic Resources Analysis Support System (GRASS), GIS for Digital Elevation Model (DEM) generation. A key aim was to make the project-derived data available over the Web. This was achieved using MapServer which allows for the representation of the derived geospatial data with pMapper providing the graphical Web interface. Our study highlights the process dynamics of run-off erosion in Olvera derived through the use of advanced computer-based mapping tools. The resulting map products and interpretations are available via the Internet. To date, derivative maps have been produced to improve maintenance of roads and transport and of the construction of new infrastructure.