3-D density model of Mt. Etna Volcano (Southern Italy)

A detailed density model of Mt. Etna and its surrounding areas has been evaluated using a 3-D inversion of the gravimetric data acquired in the 1980's. Several high-density and low-density bodies are found, penetrating from shallow depths as far down as 12 km bsl. A positive correlation (in terms of location, extent, density, and velocity) is established between several anomalies of the density model and features identified in previously published seismic tomographies. A prominent high-density body extending down to 7 km bsl is recognized in the southern part of the Valle del Bove, and interpreted as a solidified magmatic intrusion. On the western boundary of this anomaly, a low-density body is interpreted as a bubble and liquid magma mixture. Outside the central area, three other high-density anomalies are imaged and attributed to the earliest phases of volcanic activity in the area. Several interesting low-density anomalies are also identified and correlated with known fault lines and other structural features of the region.     

Considering large earthquake clustering in seismic risk analysis

Earthquakes cluster in space and time resulting in nonlinear damage effects. We compute earthquake interactions using the Coulomb stress transfer theory and dynamic vulnerability from the concept of ductility capacity reduction. We combine both processes in the generic multi-risk framework where risk scenarios are simulated using a variant of the Markov chain Monte Carlo method. We apply the proposed approach to the thrust fault system of northern Italy, considering earthquakes with characteristic magnitudes in the range ~[6, 6.5], different levels of tectonic loading \(\dot{\tau }\) = {10^?4, 10^?3, 10^?2} bar/year and a generic stock of fictitious low-rise buildings with different ductility capacities μ _Δ = {2, 4, 6}. We describe the process’ stochasticity by non-stationary Poisson earthquake probabilities and by binomial damage state probabilities. We find that earthquake clustering yields a tail fattening of the seismic risk curve, the effect of which is amplified by damage-dependent fragility due to clustering. The impact of clustering alone is in average more important than dynamic vulnerability, the spatial extent of the former phenomenon being greater than of the latter one.     

The 2014 seismic hazard model of the Middle East: overview and results

The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org).     

A performance‐based framework for adaptive seismic aftershock risk assessment

Operative seismic aftershock risk forecasting can be particularly useful for rapid decision‐making in the presence of an ongoing sequence. In such a context, limit state first‐excursion probabilities (risk) for the forecasting interval (a day) can represent the potential for progressive state of damage in a structure. This work lays out a performance‐based framework for adaptive aftershock risk assessment in the immediate post‐mainshock environment. A time‐dependent structural performance variable is adopted in order to measure the cumulative damage in a structure. A set of event‐dependent fragility curves as a function of the first‐mode spectral acceleration for a prescribed limit state is calculated by employing back‐to‐back nonlinear dynamic analyses. An epidemic‐type aftershock sequence model is employed for estimating the spatio‐temporal evolution of aftershocks. The event‐dependent fragility curves for a given limit state are then integrated together with the probability distribution of aftershock spectral acceleration based on the epidemic‐type aftershock sequence aftershock hazard. The daily probability of limit state first‐excursion is finally calculated as a weighted combination of the sequence of limit state probabilities conditioned on the number of aftershocks. As a numerical example, daily aftershock risk is calculated for the L'Aquila 2009 aftershock sequence (central Italy). A representative three‐story reinforced concrete frame with infill panels, which has cyclic strength and stiffness degradation, is used in order to evaluate the progressive damage. It is observed that the proposed framework leads to a sound forecasting of limit state first‐excursion in the structure for two limit states of significant damage and near collapse. Copyright © 2014 John Wiley & Sons, Ltd.     

The city of Matera and its ‘Sassi’ (Italy): an opportunity to broadcast geology in the European Capital of Culture 2019

Matera is an ancient city located at the top of Italy's high heel that has been anointed the European Capital of Culture 2019 and which, since 1993, has been included in the UNESCO World Heritage list. The close relationship between the urban development of the old town and its geology offers the unique opportunity to discover, in one shot, the cultural and geological history of a wonderful city that is often left out of the spotlight. As a corollary to this, the rupestrian old town of Matera and nearby areas are known also for having been the location of several movies (e.g. Bond 25 ‘No time to die’). Accordingly, media and tourists alike are showing a growing interest in Matera.     

Lava stones from Neapolitan volcanic districts in the architecture of Campania region,Italy

Results of a research carried out on the lavas from Campi Flegrei and Somma-Vesuvius volcanic districts are reported here. The lavas have been widely employed, since Roman age, in several important monumental buildings of the Campania region, mainly in the town of Naples and in its province. They are classified as trachytes (Campi Flegrei products), tephri-phonolites and phono-tephrites (Somma-Vesuvius complex) from a petrographical point of view. Sampling was carried out from well-known exploitation districts. A substantial chemical difference between the products of the two sectors was confirmed, while petrophysical characterization evidenced similarity among the two different materials, although some differences were recorded even in samples coming from the same exploitation site.     

Recursive anisotropy: a spatial taphonomic study of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi,Mygdonia Basin,Greece

By applying advanced spatial statistical methods, spatial taphonomy complements the traditional taphonomic approach and enhances our understanding of biostratinomic and diagenetic processes. In this study, we elaborate on a specific aspect – spatial anisotropy – of taphonomic processes. We aim to unravel the taphonomic history of the Early Pleistocene vertebrate assemblage of Tsiotra Vryssi (Mygdonia Basin, Greece). Circular statistics are used for the fabric analysis of elongated elements; geostatistics (directional variograms), wavelet and point pattern analyses are applied for detecting anisotropy at the assemblage level. The anisotropy of magnetic susceptibility (AMS) of sedimentary magnetic minerals is also investigated. The results, integrated with preliminary remarks about the differential preservation of skeletal elements, sedimentological and micromorphological observations, suggest multiple dispersion events and recurrent spatial re‐arrangement of a lag, (peri)autochthonous assemblage, consistent with the cyclical lateral switching of a braided fluvial system. Furthermore, this study offers a contribution to the building of a spatial taphonomic referential framework for the interpretation of other fossil vertebrate assemblages, including archaeo‐palaeontological ones.