Carveni, P.

Mount Etna is the largest active volcano of Europe and the highest mountain (about 3,330 m a.s.l.) of peninsular and insular Italy; moreover, during the Last Glacial Maximum (LGM, 25,000 ÷ 14,000 years BP) it was some hundreds meters higher than today. Since other mountains of the Apennines were covered by glaciers during the Upper Pleistocene, several authors hypothesized that a glacial cover could have been also present on Mount Etna during the LGM, being the estimated limit of perpetual snow around 2,500 m a.s.l. at that time and latitude. We have carried out a morphological survey in a portion of the volcanic edifice where rocks older than the LGM outcrop. This portion includes Punta Lucia, on the NW slope, and Serra delle Concazze, on the NE slope. Along the upper part of the northeastern slope of Etna we have found a small valley, about 170 m long, 15 m wide and 7 m deep, characterized by a clear U-shaped section, that we interpreted to be of glacial origin. The search for moraine deposits that could be ascribed to the activity of the hypothesized glacier was unsuccessful so far and is also complicated by the presence of vegetation and recent lava and tephra deposits covering the volcano flanks. We are aware that this valley should be considered as a possible geomorphosite to guarantee its preservation and further study.

A study aimed to shed some light on building collapse caused by the strongest earthquakes in the San Raineri Peninsula (Messina) is here reported. Although a compilation of structurally damaged buildings is widely reported in historical sources, the interpretation of seismic collapse has often been doubtful or ambiguous. We therefore performed an exhaustive and detailed review of seismic effects caused by the 1783 and 1908 earthquakes on the peninsula buildings. Geological and geotechnical data were also collected on the peninsula. The results of boring data reveal high seismic vulnerability for the peninsula in some areas. The study shows that the ancient buildings were damaged by settlement due to soil liquefaction rather than by seismic shaking of the large walls. The obtained results show that further investigations must be carried out in this area for a correct town planning of the peninsula.

The row of pyroclastic cones named Mts. Sartorius, outcropping on the NE flank of Etna, formed in 1865 during a lateral eruption that lasted about 6 months. The event was eye witnessed and described by numerous scientists and reporters. In this work, we use their observations to reconstruct the eruption chronology and scenario, and carry out a detailed geomorphologic survey to identify the eruptive features and pyroclastic deposits. The 1865 eruption began on 29 January along a segment of the main system of fractures oriented ENE–WSW, radial to the central conduit. After 30 January, a secondary system of fractures trending NNW–SSE was simultaneously active. The six larger Mts. Sartorius cones developed since 3 February along the lower extension of the radial system. They are markedly asymmetric due to the persistent winds blowing at the time and to the pre-existing topography formed on underlying deposits, previously unreported, that we have recognized. Now, about 150 years after the eruption, most of the eruptive vents and fractures are no longer observable in the field, being mostly hidden by products of subsequent phases of the eruption and by younger epiclastic deposits.

Most of the ancient town of Tindari (NE, Sicily) was settled on a plateau the most surficial layer of which was made of unconsolidated material. Ongoing excavations at the archaeological site at Tindari uncovered a large portion of the decumanus which suffered deformations preliminarily assigned to coseismic effects. An analysis of the local dynamic response through the simulation of strong seismic shaking to the bedrock and modelling of spectral ratios of the bedrock-soft soil was carried out to verify the susceptibility of superficial terrains of the promontory to coseismic deformations. To perform this simulation the finite element method (FEM) was used. Four accelerometric recordings of three earthquakes of medium-high magnitude, recorded on rocky sites, were chosen to simulate the seismic shaking, using a constitutive law for the materials composing the promontory layers both of linear-elastic type and of elastoplastic type. The analysis of the linear-elastic field allowed the definition of the frequencies for which the spectral ratios of the accelerations recorded the highest amplifications; in particular the frequency range 31.5–37.2 Hz can be combined with deformation of the paved floor of the decumanus. The analysis in the elastoplastic field highlighted the zones of promontory more susceptible to suffer plasticization process. The results show that the topmost layer of the decumanus is the most susceptible to suffer plasticization. Therefore, the performed analysis lends greater support to the hypothesis that the deformations were produced by seismic shaking.

Geosites are valuable natural resources of a territory and represent the geologic heritage of a region. In southeastern Sicily several localities in the Ragusa area can be considered and exploited as possible geosites. The area that we propose in this study belongs to the calcareous Hyblean foreland that is part of the Pelagian block, in turn belonging to the northern continental margin of the African plate. The neogenic units of the Apennine-Maghrebide orogen are thrusted onto the Hyblean foreland from the north, while to the east the Hyblean foreland is bounded by the Hyblean-Maltese Escarpment toward the Ionian Sea. Among the active tectonic structures of the study area is the Ispica normal fault system that displaces the sector to the east by 80-100 m, forming the depression of Ispica-Capo Passero. The Ispica area is characterized by deep gorges, locally called “cave”, which origin is due to fluvio-karstic processes that acted along pre-existing structural discontinuities. In this work we describe in particular the Cava d’Ispica, a 13-km long valley extending in the NW-SE direction within the territory of Modica, Ispica and Rosolini. It is an area of relevant interest both for the beauty of the landscape and for its historical and archaeological importance. Inside the Cava d’Ispica is a number of caves of different size where the first inhabitants of the area used to live (the first settlings are dated 2000 b.C.). These caves also hosted the Sicilians escaping from the nearby coastal areas after the arrival of the Greek settlers. In the IV-V centuries hundreds of these caves were used as a cemetery complex, while during the barbaric invasions and the following Byzantin age (VI-IX centuries) they were mostly utilized by local people as shelters. At the entrance of the valley is the archeologic park called “Parco della Forza”, whose name derives from the latin word “Fortilitium” because of the presence of a fortress. In the northern part of the park is the unique and spectacular Centoscale, a well carved in the calcareous rock that, with its 250 steps, reaches the bottom of the valley located 60 m below. In 1972 the Soprintendenza ai Beni Culturali started an excavation in the Cava d’Ispica area and the archaeological findings are now exhibited within the Antiquarium museum of the park.

In ancient times, the name “Peloro” was used to indicate an anthropic area that gradually developed around the first known human settlement on the Sicilian shore near the Straits of Messina. Since the 5th century BC, historians have documented that numerous naval armadas landed for long periods at Peloro. However, the present-day morphology of the Peloro Cape Peninsula does not have any protected inlet that would offer a location to repair hundreds of ships, as has been documented by historical sources. To address this discrepancy, geomorphologic data were collected and analyzed to verify whether historical documents were consistent with the palaeotopography of the area. This approach is based on the analysis of the morphotectonic evolution of the coastal lowland that resulted from regional uplift over the Quaternary and Holocene. The results indicate that the harbour was located in the basin of the Pantano Piccolo salt marsh, and was large and deep enough to have sheltered up to 320 ships.

The results of geological and geomorphologic surveys on the salt marsh of Ganzirri (Pantano Grande), combined with geophysical researches and historiographical data, are reported here to define the genesis of the marsh and to evaluate the physical factors that influenced its recent evolution. The genesis of the Pantano Grande may be due to a state of equilibrium reached between differential lowering of the coastal plain, confined by normal faults, and generalized chain uplift. In particular, two normal faults are considered: the first borders the northern shore of the Pantano Grande, and the second bounds the Ionian coastal plain towards the south. Concerning the recent evolution of the Pantano Grande the importance of the sterile conglomerate outcrop, which borders the Ganzirri coastal plain, is stressed. The conglomerate is interposed between sediments that define the Pantano Grande basin, and the Ionian Sea, and influenced the water exchange between the marsh and the sea. Before the excavation of two canals that link up the Pantano Grande with the sea, the conglomerate, limiting the spread of benthic species, has definitively affected the ecological structure of the original marsh.

Unique volcanic structures, known in the literature as “lava trees” and “tree molds”, have formed at several sites on Mt. Etna volcano (northeastern Sicily, Italy). They form when a fluid lava flow runs over a tree, wraps around it and, while the wood burns off, solidifies forming a hollow cast of the tree. The inhabitants of the Etna area call these formations “pietre cannone” (“cannon stones”) because of their cylindrical shape. The first documentation of lava trees is from Hawaii, but the first eye-witnessed accounts of their formation are, to our knowledge, from Etna’s 1865 eruption. Although many of the literature examples of lava trees and tree molds formed in pahoehoe, many of those reported in this work formed in a’a. The sites where we have found the lava tree molds are located within the territory of the Etna Regional Park; most occur next to walking trails and have a high potential for geotourism.

A geomorphologic survey was performed along the shoreline extending for about 3 km between the beache of Santa Maria del Focallo and Porto Ulisse, on the southeastern coast of Sicily. The study area belongs to the territory of Ispica, within the Ragusa province. This area is characterized by anthropic activities due to the agricultural and turistic use of the territory. Here the coastline is featured by cliffs made of calcarenitic breccia and sandy levels with Strombus coronatus (Upper Pliocene). The maximum elevation of the cliffs is 12 m a.s.l.. At the base of the cliffs are a number of caves caused by marine erosion. This process causes rockfalling and the formation of small, short-living sandy beaches. Further, the presence of several stacks is evidence of a progressive and fast coastline retreat. An interesting phenomenon can be observed at the artificial harbour of Punta Cirica, where marine erosion has excavated small caves along pre-existing fault planes. In some of these caves the partial collapse of the roof has caused the formation of sink holes.

We have studied four mud volcano fields located in eastern Sicily, around the Mt. Etna edifice. Three of them are located on the southern flank of Etna, between the Paternò and Belpasso villages and, based of their location, are named “Salinelle dei Cappuccini”, “Salinelle del Fiume” and “Salinelle del Vallone Salato”. Their genesis is connected with a structural trap formed by a brachyanticline of Pleistocene clays that form the Etna basement. The fourth one is located on the farest north-eastern part of Etna, along the Ionian coastline, and it is named “Salsa di Fondachello” after the name of the closest village. Geologic surveys and drilling data allow us to say that in “Salinelle dei Cappuccini” and “Salinelle del Fiume” fluids uprise through pre-existing volcanic necks, while in “Salinelle del Vallone Salato” fluids presumably uprise through a fault plane. The morphological evolution of these mud volcano fields depends mainly on the density of the emitted muds and secondarily on preexisting features of the ground surface. Chemical analyses revealed that the water coming out from the mud volcanoes is a fossil marine water hosted in the Miocene sedimentary rocks of the Mt. Etna basement. CO2 is the most abundant escaping gas, and it is mainly of magmatic origin: its amount and rate could be related to movements of the deep Etna magma. The activity of the “Salsa di Fondachello” mud volcano started on January 11th, 1693, associated with the destructive Val di Noto earthquake. The mud volcano was again active from 1795 to 1832. At the end of its last activity, started in March 1847, an earthquake occurred and the mud volcano collapsed. Today only a weak methane emission is evidence of endogenous activity.