Nanoseismic monitoring for detection of rockfalls. Experiments in quarry areas

Le frane per crollo da ammassi rocciosi fratturati sono tra i processi di instabilità gravitativa che più frequentemente interessano opere antropiche quali tagli su versanti naturali o artificiali, pareti di cava, trincee stradali, autostradali o ferroviarie, sia per ciò che attiene le aree di distacco che per quelle di accumulo. Nell’ambito dell’applicazione di sistemi di early warning per la gestione del rischio geologico legato a queste tipologie di frana, una sperimentazione della tecnica del monitoraggio nanosismometrico è stata effettuata presso due siti estrattivi non più in attività: le “Pirrere” della Baia di Cala Rossa sull’isola di Favignana (Trapani), in Sicilia, e la cava dismessa di Acuto (Frosinone), in Italia Centrale. Il monitoraggio nanosismometrico è una tecnica di indagine che consente di individuare e localizzare deboli eventi sismici, fino a magnitudo locale (ML) nell’ordine di -3, attraverso l’impiego di quattro sensori sismometrici disposti secondo una specifica geometria di array detta SNS (Seismic Navigation System). Nel presente lavoro, mediante il software NanoseismicSuite sono stati analizzati 73 eventi di crollo indotti artificialmente attraverso la caduta controllata di blocchi di roccia nei due siti estrattivi abbandonati; sono stati lanciati, simulando fenomeni di rockfalls, rispettivamente 47 blocchi di roccia nella cava di Acuto e 26 eventi in quattro diverse cave a cielo aperto presenti nel settore occidentale di Cala Rossa. Tali eventi, avendo punto epicentrale noto, hanno permesso di determinare il miglior modello di sottosuolo in termini di valori di velocità delle onde P ed S attraverso un’operazione di back analysis. L’analisi è stata, infatti, effettuata variando i valori di velocità e scegliendo quelli relativi all’epicentro teorico ottenuto dall’analisi dell’evento che fosse il più vicino possibile al punto reale di impatto del blocco di roccia. Al fine di valutare la sensibilità della geometria dell’array SNS e l’influenza del sito di installazione sulla capacità di individuare e localizzare gli eventi, le sperimentazioni sono state condotte sia variando il raggio di apertura che la zona di installazione degli array: presso Acuto le acquisizioni di segnale sono state condotte prima con un array SNS con apertura di 20 m e successivamente con un array di apertura 10 m, mentre presso Cala Rossa l’array è stato installato alternativamente all’aperto in un’area di plateau roccioso ed in una galleria facente parte dell’area di cava abbandonata. Analizzando i dati si è ottenuta una precisione dell’ubicazione epicentrale compresa tra il 10 ed il 22% della distanza che intercorre tra la sorgente e l’array nanosismometrico. Il miglior modello di sottosuolo ottenuto per entrambi i casi di studio è risultato avere una velocità delle onde P pari a 900 m/s ed un rapporto VP/VS pari a 1.73, valori in accordo con le condizioni di intenso stato di fratturazione delle rocce carbonatiche affioranti nelle due zone di cava. Per gli eventi di crollo indotti la magnitudo ML è risultata essere compresa tra -2.8 e -1.3; considerando l’energia sviluppata dall’impatto, legata alla massa del blocco ed all’altezza e alla velocità di caduta, non è stato possibile definire una relazione tra magnitudo ed energia, probabilmente a causa delle differenti caratteristiche del punto di impatto dei diversi blocchi. In generale, si è osservato che la precisione di ubicazione degli eventi, in termini di azimuth e distanza dal reale epicentro, è risultata paragonabile sia variando l’apertura dell’array che variando il sito di installazione. Per il sito sperimentale di Acuto, il processo di picking manuale del tempo di primo arrivo delle onde P è risultato essere più affidabile nel caso di array con apertura pari a 10 m. La sperimentazione effettuata a Cala Rossa ha permesso, invece, di osservare una migliore capacità di individuazione degli eventi nelle tracce relative all’array posizionato in galleria a causa della minore rumorosità di base del sito di installazione. Tra le registrazioni sismometriche sono state identificate varie tipologie di segnali, oltre a quelli generati dal lancio dei blocchi, alcune riconducibili ad eventi naturali di crollo altre a deboli terremoti. L’analisi dei segnali riferibili alla prima tipologia di eventi naturali, effettuata tenendo in considerazione i modelli di sottosuolo precedentemente calibrati, ha portato all’identificazione in ambedue i siti di aree aventi maggiore suscettibilità a frane per crollo. In definitiva, si può ritenere che i risultati ottenuti in questo studio siano incoraggianti rispetto all’efficacia della tecnica di monitoraggio nanosismometrico nell’individuazione e nell’ubicazione di fenomeni di crollo in roccia e portano a ritenere questa tecnica potenzialmente applicabile in aree in cui tali eventi possono interferire con infrastrutture antropiche.In the frame of early warning and risk mitigation studies for landslide processes involving rock masses, two quarry areas (Cala Rossa Bay in Sicily and Acuto in Central Italy) were monitored with SNS (Seismic Navigation System) arrays. In this study, 73 rockfalls were simulated by launches of rock blocks. This allowed to perform a back analysis for defining the best seismic velocity model of the subsoil half-space; the records related to each impact caused by the rock block launch were managed by the nanoseismic monitoring approach, varying the velocity model to obtain a theoretical epicentre as close as possible to the actual location of the impact point. In order to evaluate the sensibility of the SNS array, the results obtained by different array apertures and positions were compared in terms of azimuth and distance error with respect to the real epicentres. On the other hand, several natural rockfalls were detected; their analysis allowed to identify areas having higher susceptibility to rockfalls by using the previously calibrated subsoil half-space model. Further studies are required to better define the areas prone to rockfall generation in the considered test sites; nevertheless, the here obtained results show an encouraging perspective about the application of the nanoseismic monitoring with respect to vulnerable infrastructures in rockfall prone areas

Recorded displacements in a landslide slope due to regional and teleseismic earthquakes

Regional and teleseismic earthquakes can induce displacements along joints in a landslideinvolved rocky slope in Central Italy. The rarity of these effects is due to specific physical properties of the seismic signals associated with: (i) the energy content, (ii) the distribution of relative energy and peak of ground acceleration related to the ground motion components and (iii) the spectral amplitude distribution in the frequency domain; these properties allow the triggering earthquakes to be distinguished from the others. The observed effects are relevant when compared to the direction of the landslide movement and the dimensions of the involved rock mass volume. The landslide movement is less constrained in the direction parallel to the dip of the slope and the landslide dimensions are associated with characteristic periods that control the landslide deformational response in relation to the spectral content of the ground motion. The earthquake-induced displacements are significant because they have the same order of magnitude as the average annual cumulative displacement based on a decade of strain measurements within the slope

The Gluon Propagator in Momentum Space

We give preliminary numerical results for the gluon propagator evaluated both in coordinate and momentum space on a 16^3X40 quenched lattice at beta=6.0. Our findings are compared with earlier results in the literature at zero momentum. In addition, by considering nonzero momenta we attempt to extract the form of the propagator and compare it to continuum predictions formulated by Gribov and others. latex, file espcrc2.sty needed (appended at the end: search for espcrc2.sty).Comment: 4 page

An Exploratory Study on the Influence of Psychopathological Risk and Impulsivity on BMI and Perceived Quality of Life in Obese Patients

The present study aimed to assess the psychological profiles of adult male and female obese patients, as well as to verify the possible influence of their psychopathological risk and impulsivity on their body mass index (BMI) and perceived quality of life. A total of 64 obese subjects accessing a center for care of their obesity were assessed through anthropometric and psychometric measurements. All anthropometric measures in men were higher than in women, while in turn, women showed higher psychopathological symptoms. Furthermore, the symptoms of somatization and psychoticism were predictors for a higher BMI in men, but there was no effect of psychopathological symptoms on the perceived quality of life (QoL) of male subjects. Moreover, in women, somatization and attentional impulsivity were predictors for a higher BMI, whereas no correlation was found between their psychopathological risk and perceived QoL. The results of regression analysis underlined that somatization is a “core” psychopathological symptom in obese subjects regardless of their sex, which is a potential predictor for a higher BMI. The psychological difficulties of the subjects had no effect on their perceived QoL, suggesting that they find it difficult to reflect on the impact that obesity has on their life

Lattice Gauge Fixing for Parameter Dependent Covariant Gauges

We propose a non-perturbative procedure to fix generic covariant gauges on the lattice. Varying the gauge parameter, this gauge fixing provides a concrete method to check numerically the gauge dependence of correlators measured on the lattice. The new algorithm turns out to converge with a good efficiency. As a preliminary physical result, we find a sensitive dependence of the gluon propagator on the gauge parameter.Comment: 10 pages (LaTeX2e), 5 eps figure

Lattice Renormalization of Quark Operators

We have technically improved the non-perturbative renormalization method, proposed by Martinelli et al., by using quark momentum sources and sinks. Composite two-fermion operators up to three derivatives have been measured for Wilson fermions and Sheikholeslami-Wohlert improved fermions in the quenched approximation. The calculations are performed in the Landau gauge on 16^3x32 lattices at beta = 6.0 for 3 kappa values in each case. The improved sources greatly decrease the statistical noise. We extract and discuss here renormalization factors for local operators and moments of the structure functions for Wilson fermions.Comment: 3 pages, Latex, 6 figures. epsf.sty and espcrc2.sty needed. Talk given at Lattice9

Human-Animal Interaction in Animal-Assisted Interventions (AAI)s: Zoonosis Risks, Benefits, and Future Directions—A One Health Approach

: Animal-assisted interventions (AAI)s represent the expression of integrated medicine, according to the One Health approach. Actually, animal-assisted therapies and animal-assisted activities are implemented in hospitals, rehabilitation centers, etc. The efficacy of AAIs is based on interspecific interactions and would be impacted by different factors, such as the characters of both the animal and the handler, a suitable selection of animal species, an appropriate animal educational protocol, the relationship between the handler and the animal, and mutual relationship among the animal, the patients, and members of the working team. AAIs produce many advantages for the patients but could expose them to zoonotic-pathogens transmission. Therefore, positive animal welfare, as preventative medicine to avoid incidents or transmission of zoonosis, is a relevant aspect with implications for human and animal health and wellbeing. This review aims to summarize the current published knowledge regarding the occurrence of pathogens in AAIs and to discuss their relevance in light of health and safety in AAIs participants. In addition, this review will contribute to defining the state of the art of AAIs through a careful benefits/challenges analysis and offers discussion points on the possible future developments according to the One Health approach

Lesions associated with mineral deposition in the lymph nodes and lungs of cattle: a case-control study of environmental health hazard.

This report focuses on the state of health of the cattle raised in the district of Taranto - city of Italy rated as environmentally at risk. Representative samples of lungs, bronchial and mediastinal lymph nodes of cattle from district of Taranto's slaughterhouses were collected. After a macroscopic examination, samples with marked lesions were processed for light microscopy. Samples were also observed with polarized light microscopy, scanning electron microscopy and with microanalysis. The macroscopic examination revealed that 60 out of 183 samples showed marked lesions. Lung alterations were characterized by thickening of the alveolar septa and by the latter's modifying action on the alveolar spaces, foci of fibrosis and bronchopulmonary inflammation. For 51 out of the 60 samples observed, the histological examination confirmed the presence of pneumoconiosis and lymph nodal anthracosis. Energy-dispersive X-ray microanalysis of lung samples identified a wide range of elements including silicon, aluminium, titanium, iron, carbon and small amount of the other metals. In the lymph-nodes the same kind of metals with a different levels of distribution was observed. Our survey on cattle farmed in areas at high risk of pollution may be helpful to the estimation of the exposure risk for man to environmental contaminants and to the evaluation of the occurrence of the pathological manifestations as well

Non-Perturbative Renormalisation of Composite Operators

It is shown that the renormalisation constants of two quark operators can be accurately determined (to a precision of a few per-cent using 18 gluon configurations) using Chiral Ward identities. A method for computing renormalisation constants of generic composite operators without the use of lattice perturbation theory is proposed.Comment: 3 pages, uuencoded compressed postscript file, to appear in the Proceedings of the International Symposium on Lattice Field Theory, Dallas, Texas, 12-17 October 1993, Southampton Preprint 93/94-0