Impact of different regression frameworks on the estimation of the scaling properties of radar rainfall

Rainfall is characterized by high variability both in space and time. Despite continuous technological progress, the available instruments that are used to measure rainfall across several spatio-temporal scales remain inaccurate. To remedy this situation, scaling relationships of spatial rainfall offer the potential to link the observed or predicted precipitation quantities at one scale to those of interest at other scales. This paper focuses on the estimation of the spatial rainfall scaling functions. Standard scaling analysis constructed by means of the ordinary least squares method often violates such basic assumptions implicit in its use and interpretation as homoschedasticity, independence, and normality of the errors. Consequently, the authors consider alternative regression frameworks i.e. bootstrapping regression, semi parametric linear model, and multilevel normal linear model to show how these different approaches exert a significant impact on the multifractal analysis of radar rainfall. In addition, the uncertainties associated with the construction of the scaling function due solely to the regression procedure are quantified. The radar data come from the polarimetric C-band weather radar located in Rome, Italy, and the scaling properties are computed for a square domain centred on the radar site with a side length of 128 km and a finest resolution of 1 km².     

The Lithosphere-Asthenosphere System in the Calabrian Arc and Surrounding Seas – Southern Italy

A fairly detailed structural model of the lithosphere-asthenosphere system (thickness, S- and P-wave velocities of the crust and of the uppermost mantle layers) has been defined in the Calabrian Arc region (Southern Tyrrhenian Sea, Calabria and the northwestern part of the Ionian Sea) in Southern Italy using seismic data from literature as a priori constraints of the nonlinear inversion of surface-wave data. The main features identified by this study are: (1) A very shallow (less then 10 km deep) crust-mantle transition in the Southern Tyrrhenian Sea and a very low v_s just below a very thin lid, in correspondence of the submarine volcanic bodies Magnaghi, Marsili and Vavilov, while the v_s in the lid is quite high in the area that separates Marsili from Magnaghi-Vavilov; (2) a shallow and very low v_s layer in the uppermost mantle in the areas of the Aeolian Islands, Vesuvius, Phlegraean Fields and Ischia, which represents their shallow-mantle magma source; (3) a thickened continental crust and lithospheric doubling in Calabria; (4) a crust about 25-km thick and a mantle velocity profile versus depth consistent with the presence of a continental rifted lithosphere, now thermally relaxed, in the investigated part of the Ionian Sea; (5) the subduction towards northwest of the Ionian lithosphere below the Southern Tyrrhenian Sea; (6) the subduction of the Adriatic/Ionian lithosphere underneath the Vesuvius and Phlegraean Fields.     

Holocene climate phases from buried soils in Tigray (northern Ethiopia): comparison with lake level fluctuations in the Main Ethiopian Rift

Stratigraphic analysis of alluvial/colluvial sequences and ¹⁴C dating have been used as proxies for Holocene climate changes in the highlands of Tigray (northern Ethiopia). The studied records show alternations of buried soils and peaty–clayey sediments, pointing to wet, stabilization phases, and organic-free colluvium layers resulting from the abrupt occurrence of dry-climate episodes. The ¹⁴C dates, mostly unpublished, cluster in the 11,090–9915, 9465–9135, 8450–7330, 6720–3635, 2710–2345, and 1265–790 cal yr B.P. time spans. Evidence of subsequent pedogenesis is lacking in the area, apart from a buried humified horizon dated at 300 ± 60 ¹⁴C yr B.P. (460–295 cal yr B.P.). Both the timing and the pattern of Tigray paleoclimatic events fit the corresponding framework, based on lake level changes, previously implemented for the Main Rift Valley. These findings give further support for arguing that the forcing mechanisms of the wet/dry fluctuations during the Holocene were effective over a large scale.     

The bias field of dark matter haloes

Accepted 1998 January 26. Received 1998 January 26; in original form 1997 August 13This paper presents a stochastic approach to the clustering evolution of dark matter haloes in the Universe. Haloes, identified by a Press–Schechter-type algorithm in Lagrangian space, are described in terms of 'counting fields', acting as non-linear operators on the underlying Gaussian density fluctuations. By ensemble-averaging these counting fields, the standard Press–Schechter mass function as well as analytic expressions for the halo correlation function and corresponding bias factors of linear theory are obtained, extending the recent results by Mo & White. The non-linear evolution of our halo population is then followed by solving the continuity equation, under the sole hypothesis that haloes move by the action of gravity. This leads to an exact and general formula for the bias field of dark matter haloes, defined as the local ratio between their number density contrast and the mass density fluctuation. Besides being a function of position and 'observation' redshift, this random field depends upon the mass and formation epoch of the objects and is both non-linear and non-local. The latter features are expected to leave a detectable imprint on the spatial clustering of galaxies, as described, for instance, by statistics like the bispectrum and the skewness. Our algorithm may have several interesting applications, among which is the possibility of generating mock halo catalogues from low-resolution N -body simulations.     

A statistical analysis of flank eruptions on Etna volcano

A singularly complete record exists for the eruptive activity of Etna volcano. The time series of occurrence of flank eruptions in the period 1600–1980, in which the record is presumably complete, is found to follow a stationary Poisson process. A revision of the available data shows that eruption durations are rather well correlated with the estimates of the volume of lava flows. This implies that the magnitude of an eruption can be defined directly by its duration. Extreme value statistics are then applied to the time series, using duration as a dependent variable. The probability of occurrence of a very long (300 days) eruption is greater than 50% only in time intervals of the order of 50 years. The correlation found between duration and total output also allows estimation of the probability of occurrence of a major event which exceeds a given duration and total flow of lava. The composite probabilities do not differ considerably from the pure ones. Paralleling a well established application to seismic events, extreme value theory can be profitably used in volcanic risk estimates, provided that appropriate account is also taken of all other variables.     

Detection of seismic façade damages with multi-temporal oblique aerial imagery

ABSTRACT

Remote sensing images have long been recognized as useful for the detection of building damages, mainly due to their wide coverage, revisit capabilities and high spatial resolution. The majority of contributions aimed at identifying debris and rubble piles, as the main focus is to assess collapsed and partially collapsed structures. However, these approaches might not be optimal for the image classification of façade damages, where damages might appear in the form of spalling, cracks and collapse of small segments of the façade. A few studies focused their damage detection on the façades using only post-event images. Nonetheless, several studies achieved better performances in damage detection approaches when considering multi-temporal image data. Hence, in this work a multi-temporal façade damage detection is tested. The first objective is to optimally merge pre- and post-event aerial oblique imagery within a supervised classification approach using convolutional neural networks to detect façade damages. The second objective is related to the fact that façades are normally depicted in several views in aerial manned photogrammetric surveys; hence, different procedures combining these multi-view image data are also proposed and embedded in the image classification approach. Six multi-temporal approaches are compared against 3 mono-temporal ones. The results indicate the superiority of multi-temporal approaches (up to ~25% in f1-score) when compared to the mono-temporal ones. The best performing multi-temporal approach takes as input sextuples (3 views per epoch, per façade) within a late fusion approach to perform the image classification of façade damages. However, the detection of small damages, such as smaller cracks or smaller areas of spalling, remains challenging in this approach, mainly due to the low resolution (~0.14 m ground sampling distance) of the dataset used.     

Fault-generated mountain fronts in the central apennines (Central Italy): Geomorphological features and seismotectonic implications

The morphotectonic framework of the Central Apennines is given by faulted blocks bounded by normal faults, mostly trending NW–SE, NNW–SSE and NE–SW, which cut previous compressive structures. Such a structural setting is consistent with the focal mechanisms of the earthquakes which often occur in this area. In this paper, three lithologically different normal fault-generated mountain fronts are analysed in order to assess the relations between their geomorphic features and active tectonics. They border the Norcia depression (Sibillini Mts, Umbria), the Amatrice–Campotosto plateau (Laga Mts, Lazio) and the Fucino basin (Marsica Mts, Abruzzi). The Norcia depression is bounded by a N20°W trending normal fault to the east and by a parallel antithetic fault to the west. The main fault has a 1000 m throw and gives rise to a wide fault escarpment, characterized by: (1) sharp slope breaks due to low angle gravity faults; (2) important paleolandslides; and (3) several fault scarplets on the piedmont belt affecting Quaternary deposits. The Amatrice–Campotosto plateau is delimited by the western slope of Mt Gorzano which runs along a N20°W trending normal fault having a 1500m throw. Minor parallel faults dislocate Quaternary landforms. Large-scale massmovements also occur here. The Fucino basin was struck by the 1915 Avezzano earthquake (I=XI MCS) which produced extensive surface faulting along two parallel NW trending normal fault escarpments on the eastern border of the basin. There is paleoseismic evidence including buried gravity graben in Late Glacial gravels and tectonic dip-slip striations on Holocene calcitic crusts covering bedrock normal fault planes. These data suggest that active extensional tectonics plays a major role in the slope morphogenesis of the Central Apennines and they indicate the importance of geomorphic analysis in seismic zonation of this area.     

Microsismi meteorici

Riassunto Ricordata la legge delle registrazioni a Venezia dei microsismi generati dai cicloni dell'Atlantico NE, e riportati fatti nuovi e nuovi studi che la confermano, trovate insufficienti altre spiegazioni del fenomeno, e introdotto il confronto con lePulsazioni della pressione atmosferica di periodo inferiore cd un'ora, ultimamente studiato dall'Autore, si propone per la spiegazione una nuovaipotesi da lavoro.

---

Summary After having remembered the law of registration at Venice of the microseisms produced by the cyclones of the Atlantic NE and related the new facts and new studies which confirm it, after having found insufficient other explanations of the phenomenon and introduced the comparison withthe pulsation of the atmospheric pressure of period inferior to one hour, studied by the author lately, as explanation, a new hypothesis of work is proposed.