Topographic effects observed at Amatrice hill during the 2016-2017 Central Italy seismic sequence

The estimate of seismic site effects by experimental approaches is based on different assumptions aimed at simplifying the complex actual site conditions and related uncertainties.However,the reliability of the results can increase if the experimental data is focused on quite strong seismic sequences and the on-site acquisition of a large number of signals is deemed strategic for the assessment of the expected phenomena.Based on these considerations,the ground motion at the Red Zone sector of Amatrice hill,violently struck by the 2016-2017 Central Italy seismic sequence,was analyzed via an observational approach.A large set of weak motions(moment magnitude Mw 2.5-3.9)was analyzed in this study by means of standard(SSR)and horizontal to vertical(HVSR)spectral ratio techniques.The results from the experimental analysis of the site effects by using weak motion and noise signals show a significant amplification at the top of Amatrice hill with a remarkable polarization of the motion and changes in spectral shapes according to the topographic setting of the relief.     

Improved dynamic correction method in seismic analysis of both classically and non‐classically damped structures

A step‐by‐step approximate procedure taking into consideration high‐frequency modes, usually neglected in the modal analysis of both classically and non‐classically damped structures, is presented. This procedure can be considered as an extension of traditional modal correction methods, like the mode‐acceleration method and the dynamic correction method, which are very effective for structural systems subjected to forcing functions described by analytical laws. The proposed procedure, herein called improved dynamic correction method, requires two steps. In the first step, the number of differential equations of motion are reduced and consequently solved by using the first few undamped mode‐shapes. In the second step, the errors due to modal truncation are reduced by correcting the dynamic response and solving a new set of differential equations, formally similar to the original differential equations of motion. The difference between the two groups of differential equations lies in the forcing vector, which is evaluated in such a way as to correct the effects of modal truncation on applied loads. Copyright © 2001 John Wiley & Sons, Ltd.     

A Warning System for Stromboli Volcano Based on Statistical Analysis

In this paper we describe a warning system based on statistical analysis for the purpose of monitoring ground deformation at the Sciara del Fuoco (Stromboli Volcano, Sicily). After a statistical analysis of ground deformation time-series measured at Stromboli by the monitoring system known as THEODOROS (THEOdolite and Distancemeter Robot Observatory of Stromboli), the paper describes the solution adopted for implementing the warning system. A robust statistical index has been defined in order to evaluate the movements of the area. A fuzzy approach has been proposed to evaluate an AI (Alarm Intensity) index which indicates the level of hazard of the Sciara del Fuoco sliding.     

Natural background levels and threshold values derivation for naturally As, V and F rich groundwater bodies: a methodological case study in Central Italy

Natural background levels (NBL) and threshold values (TV) derivation is an important task for EU Member States to correctly assess the chemical status of groundwater bodies within the context of the recently adopted Groundwater Directive. Attempts are being made both by water authorities and scientific community to test application viability of proposed methods to different real situations and to develop tailored adjustments and refinements. The aim of this paper is to describe a methodological case study of NBL and TV determination in a large area (5,500 km²) located in Central Italy where both natural and anthropogenic contamination occurs, resulting in several substances be detected in ground waters with concentration frequently exceeding drinking water standards. This paper shows the key role played in the determination process by knowledge on the hydrogeological setting and hydrogeochemical features. The adoption of appropriate pre-selection criteria of samples, the establishment of TV at the groundwater body scale for natural origin substances, and the evaluation of TVs exceedances in a multiparameter context are experimentally discussed. Beyond the critical evaluation of NBL and TV determination method, this research aims at increasing consciousness in the water management agencies that groundwater status assessment should be conceived as a scientific evaluation procedure and not as a mere technical/administrative exercise to be performed using any set of available data. As such, it should be supported by adequate knowledge of hydrogeological setting, hydrochemical processes occurring in groundwater bodies, and human activities acting overland to be progressively verified.     

Solar constant and sunspots

Summary The relationship, already found by the authors, between sunspot numbers and the solar constant, as deduced from the highest global irradiance values at noon, is here reexamined and confirmed. Some attempts at explanation and further inferences are presented.     

Constitutive modeling of structured granular materials with anisotropic grain skeleton and cement bonds

Acta Geotechnica - Structured granular materials exhibit strongly anisotropic mechanical behaviours resulting from the directional properties of their microstructural components such as grain...     

Sexual reproduction in Sarcotragus spinosulus from two different shallow environments

The reproductive cycle of the demosponge Sarcotragus spinosulus from two different shallow environments (La Pierta and La Strea) of the Ionian coasts of Apulia (SE Italy) was studied from February 2006 to February 2007 in 20 tagged specimens. The sponge is viviparous. All the monitored specimens showed sexual reproduction, even if the process usually involved small portions of the sponge tissue. Most of the specimens showed hermaphroditism, with contemporaneous production of oocytes and spermatic cysts in the same reproductive season. Young oocytes occurred from June to September in specimens from La Pierta and from June to October in those from La Strea. Large mature eggs, measuring up to 200 μm, showed a peak in August to September, concomitant with the appearance of spermatic cysts, whose density values were about 100 times higher than those estimated for female elements. At La Pierta, embryos were present for 11 months, whereas at La Strea they were very scarce during the first 4 months of observation, with the results that there was a significant difference in the production of embryos between the two groups of sponges. Embryo development occurred in patches inside the choanosomal region. Cleavage started in September and led in June to a solid stereoblastula, which, only at La Pierta, produced parenchymella larva (371.3 + 31.3 μm on average) from June to July. In the specimens from La Strea, larvae were never observed. The slight differences in the reproductive cycle between the two groups of sponges may be explained in the light of the major variability of the environmental parameters which could have affected the specimens from La Strea negatively.     

Early‐middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy)

This paper compares stable isotope (δ¹⁸O and δ¹³C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ¹⁸O (δ¹⁸Os) of modern specimens (Pomatias elegans, Cornu aspersum, Eobania vermiculata, Helix ligata and Marmorana fuscolabiata). In contrast, interspecific shell δ¹³C (δ¹³Cs) variability was significant, probably due to different feeding behaviour among species. The δ¹⁸Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of ¹⁸O‐depleted winter rainfall in their δ¹⁸Os is lost. This suggests that δ¹⁸Os and δ¹³Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ¹⁸Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ¹³Cs trend suggests a transition from a slightly ¹³C‐enriched to a ¹³C‐depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ¹³Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO₂ concentration. Copyright © 2010 John Wiley & Sons, Ltd.     

Seismic study of the Mesozoic carbonate basement around Mt. Somma–Vesuvius, Italy

Fifteen seismic reflection lines from AGIP surveys, in and around the Campanian Plain and Mt. Somma–Vesuvius (south Italy) have been interpreted. The attention has been focused to the horizon pertinent to the top of the Mesozoic carbonate sequence and the Quaternary faults dissecting it. As a matter of fact, both are very important elements for understanding the origin of the volcanic activity in the area, that often in the past, has been the topic of debates not supported by reliable data. In the study area, referring to the depth of the carbonate basement, comparison between the result achieved by the seismic prospecting and previous gravity studies has been made. It shows coherence in some areas but large discrepancy within others. Near the town of S. Anastasia, the gravity and seismic depth estimates differ as much as 1000 m or more. Furthermore, the seismic data show that the source of the greatest volcanic eruption in the area (the so-called ‘Campanian Ignimbrite') is probably not located in the Acerra depression, as suggested by other authors. A main NE–SW fault directed toward Vesuvius, considered as playing a primary role on volcanogenetic processes and previously recognised only offshore by marine seismic survey, has been now identified also inland using this new seismic information. The results presented here strengthen the hypothesis that Mt. Vesuvius is located at the crossing point of two regional Quaternary sets of fault heading NW–SE and NE–SW.