Geomorfo: a program for the classification of terrain units

In order to perform a thorough quantitative analysis of the morphology of an area, a methodology has been developed, able to deal with a Digital Elevation Model (DEM), that classifies the DEM pixels starting from the eight topographical gradients, computed as differences between each pixel and the eight surrounding ones, and provides for each class a complete set of statistics of terrain attributes, including elevation, slope, and aspect. In addition, a thematic colour map may be built, with hue and saturation attributed according to both mean aspect and slope of each class, respectively. As an example, Mount Soratte in Italy has been analysed in two different ways

Geomorphometric Maps of Volcanic Areas through Multidimensional Analyses

The geomorphometric classifications of local topographic gradients for the Latera caldera (Italy) and Peteroa Volcano (Argentina) areas are introduced and compared. The adopted method is Tandem Analysis on correlation matrices. Input data are obtained by processing raster Digital Elevation Models extracted from ASTER stereopairs. The resulting maps show the spatial distribution of homogeneous landform units, highlighting the impact of erosional and tectonic processes on the whole reliefs. Moreover, each class is being described by either mean gradient values or mean topographic attributes such as elevation, slope and aspect. Next, these data are interpreted in terms of morphological setting

Viable Precursors of Paroxysmal Phenomena as Detected by Applying RQA to Acoustic Emission Time Series

Recurrence quantification analysis (RQA) represents a recent method for processing nonlinear time series, already addressed to different topics concerning earth sciences and others. RQA is applied in this work to analyze time series of acoustic emission (AE) triggered by Earth’s crust phenomena, so to detect feasible precursors of catastrophic events. The AE records of rms values were acquired at two different sites, placed close to the Peteroa volcano (Argentina) and at Valsinni (Matera, Italy), considering two ultrasound frequencies (25 and 150 kHz) with 30-sec sampling rate. The preliminary results of the application of RQA to the AE data of Valsinni with respect to the L’Aquila earthquake (Italy, on April 6, 2009), and to those related to the activity of the Peteroa volcano (Argentina) are described and appear suited to stress relationships with an impending catastrophic event

Correlation between Landforms and Ground Deformation at Nisyros Volcano (Greece)

Relief represents a major element in the characterization of a landscape that can be affected even by slight modifications on its shape, often due to ground deformation. These terrain characteristics are both linked to the topography of a given area, through a Digital Elevation Model (DEM). Topographical attributes, such as slope, aspect, elevation gradients, and others, can be provided by DEM analysis and used further as input to classification methods for defining terrain units. In this study, we explore the relationship between ground deformation and landforms in Nisyros volcano, as ground deformation seems to follow existing geomorphological patterns. Possible correlations between morphological information, collected by classifying landforms on the basis of the ~30 m spatial resolution ASTER Global Digital Elevation Model, and deformation observations resulting from Differential Synthetic Aperture Radar Interferometry (DInSAR) are performed, taking also into consideration the geostructural setting of the study area. Nisyros volcano, located at the eastern part of the active Hellenic Volcanic Arc, was investigated for the time period 2002-2010, during a dormant phase where the topography is mostly described by the geological/tectonic structure. In terms of DInSAR technique, the entire archive of ENVISAT images was used, in both ascending and descending mode, to derive the deformation rates. For the geomorphic consideration Tandem Analysis was implemented through a mixed classification procedure following a principal component analysis applied to local elevation gradients, extracted considering each pixel of the DEM and its nearest neighbours. The projection of the DInSAR results on the obtained factor spaces allows evaluating the homogeneity of the deformation in the pixels belonging to the same classes

Road Asphalt Pavements Analyzed by Airborne Thermal Remote Sensing: Preliminary Results of the Venice Highway

This paper describes a fast procedure for evaluating asphalt pavement surface defects using airborne emissivity data. To develop this procedure, we used airborne multispectral emissivity data covering an urban test area close to Venice (Italy).For this study, we first identify and select the roads’ asphalt pavements on Multispectral Infrared Visible Imaging Spectrometer (MIVIS) imagery using a segmentation procedure. Next, since in asphalt pavements the surface defects are strictly related to the decrease of oily components that cause an increase of the abundance of surfacing limestone, the diagnostic absorption emissivity peak at 11.2μm of the limestone was used for retrieving from MIVIS emissivity data the areas exhibiting defects on asphalt pavements surface.The results showed that MIVIS emissivity allows establishing a threshold that points out those asphalt road sites on which a check for a maintenance intervention is required. Therefore, this technique can supply local government authorities an efficient, rapid and repeatable road mapping procedure providing the location of the asphalt pavements to be checked

The remarkable coherence between two Italian far away recording stations points to a role of acoustic emissions from crustal rocks for earthquake analysis

We observed a remarkable near-to-unity correlation between the time series of Acoustic Emissions (AEs) collected at two stations approximately 300 km apart from each other and located along the Apennine belt (Italy). This finding prompted us to verify the hypothesis that AE signals can carry with them an indication of anomalies in a crustal stress trend, possibly related to earthquake occurrences. Thus, we checked the ability of Recurrence Quantification Analysis and Fractal Analysis as applied to AE to identify signal phase transitions before the crisis occurs. The sharp drop of the Percent of Determinism after its maximum value, and simultaneously with minimum values of the Fractal Dimension (D), few days before some seismic events take place, seems to point to the relevance of the proposed approach as precursor detection

Seismic characterization of the Quaternary sediments at Llancanelo-Lake Area, Argentina

A preliminary near-surface seismic survey was carried out at LlancaneloLake (Argentina) with the aim of mapping the quaternary layers, composed of sedi-mentary layers overlying basalt. A geological model has been obtained by interpretingthe events of a common-shot gather. Expressions of the traveltimes of the direct andrefracted waves versus o set provide means to evaluate the velocities of the layers andthickness of the upper layer. Moreover, the standard processing sequence is appliedto the data to obtain a stacked section. This procedure reveals the location of deeperinterfaces, although it is highly a ected by the ltering of the direct and refractedevents, which have the same slope of the medium- and far off set reflection signals.The fact that the direct arrival has not a zero intercept time indicates the pres-ence of a very thin layer at the surface (shallow salt deposits). Further evidence ofthe near-surface layer is that the refracted and reflection events are ringing and thereare strongly dispersive Rayleigh waves. An interface has been found approximately be-tween 54 and 57 m depth. The P- and S-wave velocities of the shallow layer are 2000and 550 m/s, according to the slopes of the direct and Rayleigh waves, respectively,and rock-physics empirical relations, while the lower layer has a P-wave velocity of2800 m/s, obtained from the refracted event. A tentative interpretation of the apexof a reflection event locates the top of the basalt layer at 190 m depth approximately.A viscoelastic model has been de ned, with quality factors of typical volcaniclasticsediments. We then compute a synthetic common-shot gather and snapshots by meansof full-wave pseudospectral methods. The synthetic gather resembles the real one, pro-viding additional support to the interpretation.Fil: Carcione, Jose M.. Istituto Nazionale di Oceanografía e di Geofisica Sperimentale; Italia; Universita Di Roma; Italia;Fil: de la Vega, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires; Argentina;Fil: Gei, Davide. Istituto Nazionale di Oceanografía e di Geofisica Sperimentale; Italia;Fil: Osella, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires; Argentina;Fil: Picotti, Stefano. Istituto Nazionale di Oceanografía e di Geofisica Sperimentale; Italia;Fil: Tassone, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentina;Fil: Poscolieri, Maurizio. Istituto di Acustica e Sensoristica; Italia

Prevalence and clinical significance of isolated low QRS voltages in young athletes

Aims: Low QRS voltages (peak to peak <0.5 mV) in limb leads (LQRSV) on the athlete's electrocardiogram (ECG) may reflect an underlying cardiomyopathy, mostly arrhythmogenic cardiomyopathy (ACM) or non-ischaemic left ventricular scar (NILVS). We studied the prevalence and clinical meaning of isolated LQRSV in a large cohort of competitive athletes. Methods and results: The index group included 2229 Italian competitive athletes [median age 18 years (16-25), 67% males, 97% Caucasian] without major ECG abnormalities at pre-participation screening. Three control groups included Black athletes (N = 1115), general population (N = 1115), and patients with ACM or NILVS (N = 58). Echocardiogram was performed in all athletes with isolated LQRSV and cardiac magnetic resonance (CMR) in those with ventricular arrhythmias or echocardiographic abnormalities. The isolated LQRSV pattern was found in 1.1% index athletes and was associated with increasing age (median age 28 vs. 18 years; P < 0.001), elite status (71% vs. 34%; P < 0.001), body surface area, and body mass index but not with sex, type of sport, and echocardiographic left ventricular mass. The prevalence of isolated LQRSV was 0.2% in Black athletes and 0.3% in young individuals from the general population. Cardiomyopathy patients had a significantly greater prevalence of isolated LQRSV (12%) than index athletes, Black athletes, and general population. Five index athletes with isolated LQSRV and exercise-induced ventricular arrhythmias underwent CMR showing biventricular ACM in 1 and idiopathic NILVS in 1. Conclusions: Unlike cardiomyopathy patients, the ECG pattern of isolated LQRSV was rarely observed in athletes. This ECG sign should prompt clinical work-up for exclusion of an underlying cardiomyopathy