GEOCITY: a drill-hole database as a tool to assess geological hazard in Napoli urban area

The geological investigations of Napoli city, which represent the basic data source for geological hazard assessment, are characterized by the absence of well exposed and continuous outcrops, mainly due to the development of the urbanized area occurred in the last 50 years. In order to increase the set of available geological information, a database named GEOCITY has been realized on the base of 900 drill holes with stratigraphies reflecting the main drill-hole surveys performed during the last century. The true key moments in its construction were the homogenisation of different data and the identification of the geological formations. A detailed analysis of the drill-hole raw data allowed us to define the database entities, while the features of the deposits, the distribution of products and the reference drill holes were used to identify the geological formation. The analysis performed using the GEOCITY database made it possible to better assess volcanic hazard from Campi Flegrei and Somma-Vesuvio and the hazard related to alluvial phenomena that Napoli city is exposed to.     

Composition of ciliate fauna and its seasonal changes in fluvial drift

Ciliate composition and its seasonal changes in seston depending on the discharge regime were analyzed in the lower rhithral area of the river Sava. Higher values for ciliate density, dry biomass, index of species diversity and concentration of particulate organic matter (POM) were associated with discharge peaks. Using the power model: y = ax^b ± c a significant positive correlation was found between POM and ciliate dry biomass (as dependent variables) and discharge (as independent variable). The ciliate drift constitutes 0.78% of the total annual POM transport. Depending on the discharge regime, the composition of ciliate drift reflects the temporal and structural changes in periphytic community.     

The post-collisional stabilization of thickened crust in the Southern Urals

The Urals are characterized by a depression of the Moho to a depth of 57 km. This structure is interpreted as a relic orogenic root, which has been conserved because no significant post-collisional processes occurred. However, there is evidence that voluminous post-collisional magmatism affected the lower crust. In this paper, we use thermal finite element models to quantify the influence of the post-collisional magmatism on the stabilization of the root. We show that at least 70% of the heat producing elements migrated in granitic melts from the lower crust to the upper crust. As a result the crustal heat flow reduced and the lithosphere could stabilize at a thickness of 180 km. Furthermore, we propose that a granulite metamorphic event during the thermal relaxation of the collision zone prevented the 57 km thick crust from delamination. These results strongly indicate that post-collisional processes were necessary for the stabilization of the Uralian crust and lithosphere.     

Water use efficiency of olive tree under two water treatments in Tunisian semi-arid conditions

Olive trees are grown under high evaporative demand and less precipitations that are variable in time and space especially in semi-arid conditions. The objective of this work is to determine the most efficient water treatment applied in an olive field (Olea europaea L. cv Chemlali) from the 98th to the 294th Julian day, in Tunisian semi-arid conditions. The choice of this time frame was done to control the effect of irrigation on the trees behavior in the irrigation period of the year (from April to October) and determine the most sensitive phenological stages to irrigation. For this reasons, two water treatments were applied: T100% (irrigation at 100% of Available Water Content (AWC)) and T50% (irrigation at 50% AWC). The results show that, according to leaf water potential, carbon isotope discrimination, and olive production parameters, the T50% AWC water treatment is the most efficient. The leaf water potential of the two water treatments applied has not exceeded ?2.5 MPa during the whole experiment which indicates that the trees of the two water treatments were not stressed. The T50% AWC shows a water use efficiency of 5.18 g/l compared to 2.93 g/l for T100% water treatment. This result demonstrate that Chemlali cultivar valorizes better low quantities of water rather than high quantities, so saving 50% of water resources applied will ensure the sustainability of water resources and stability of olive production.     

The 1667 Dubrovnik earthquake–some new insights

The year 2017 marks the 350th anniversary of the great 6 April 1667 Dubrovnik earthquake that caused extensive damage in a wide area around this old Dalmatian town (today in Croatia). This article presents the effects of the 1667 earthquake and examines the first few weeks following the catastrophe. Macroseismic data are reanalysed, for the first time available data are collected of the damage on the territory of Bosnia and Herzegovina (the territory which was in the 17th century under the Ottoman reign) and a new map of macroseismic intensities is presented. This map is in good agreement with the macroseismic field modelled using the SAF (Strong Attenuation at Fault Zones) model. We highlight some problems in the collection of macroseismic information, which are mainly a consequence of the complex political situation in the areas affected by the earthquake. The 1667 earthquake heavily impacted Dubrovnik and the Dalmatian coast. This event is thought to be the biggest one in the history of Dalmatia and practically defines seismic hazard in the coastal area of Croatia. For this reason, the main goals in this article are the improvement of the epicenter location and the determination of the moment magnitude.     

Iblean diatremes 3: volcanic processes on a Miocene carbonate platform (Iblean Mountains,SE-Sicily): a comparison of deep vs. shallow marine eruptive processes

Evolution and magma fragmentation processes of two contrasting, well-exposed diatreme complexes interbedded with Late Miocene calcareous marine sediments in distinct sedimentary environments of a carbonate platform (Iblean Plateau, Sicily) are compared with each other. The nephelinitic Cozzo Molino diatreme (CMD) to the east developed in shallow water (0–80 m water depth); the alkali basaltic Valle Guffari seamount (VGS) to the west grew on a deeper water carbonate ramp (150–200 m water depth). We focus on the dominant boundary conditions inferred to have governed depth of magma fragmentation and subaqueous emplacement mechanisms: water depth, physical nature of host rocks, magma composition, and inferred differences in initial volatile concentrations. There are gross similarities in the composition of the two moderately evolved magmas. The low-viscosity magmas in both diatremes were laden with xenoliths originating from mantle to lower crustal sites. Although similar, the eastern shallow water CMD was likely more volatile-rich, with magma fragmented prior to reaching the surface and the surrounding tephra cone was partly emergent. The eruptions of the entirely submarine VGS diatreme complex in the deeper water environment were dominated by interaction of soft sediment and alkali basaltic magma or a pre-fragmented volatile-particle mixture. Eruption columns were, thus, strongly damped and the submarine complex never pierced the water surface.     

Hazard and risk assessment in a complex multi-source volcanic area: the example of the Campania Region, Italy

In order to zone the territory of Campania Region (southern Italy) with regard to the hazard related to future explosive activity of Somma-Vesuvio, Campi Flegrei, and Ischia Island, we drew a multi-source hazard map for tephra and pyroclastic flows. This map, which merges the areas possibly endangered by the three volcanic sources, takes into account a large set of tephra fall and pyroclastic flow events that have occurred in the last 10 ka. In detail, for fall products at Campi Flegrei and Somma-Vesuvio we used the dispersal of past eruption products as deduced by field surveys and their recurrence over the whole area. For pyroclastic flows, the field data were integrated with VEI = 4 simulated events; about 100 simulations sourcing from different points of the area were performed, considering the different probability of vent opening. The spatial recurrence of products of both past eruptions and simulated events was used to assign a weight to the area endangered by the single volcanic sources. The sum of these weights in the areas exposed to the activity of two sources and/or to different kinds of products was used to draw a hazard map, which highlights the spatial trend and the extent of the single equivalent classes at a regional scale. A multi-source risk map was developed for the same areas as the graphic result of the product of volcanic hazard and exposure, assessed in detail from a dasymetric map. The resulting multi-source hazard and risk maps are essential tools for communication among scientists, local authorities, and the public, and may prove highly practical for long-term regional-scale mitigation planning.