Options
Speziale, Sergio
Loading...
2 results
Now showing 1 - 2 of 2
- PublicationRestrictedShallow landslide generation at La Fossa cone, Vulcano island (Italy): a multidisciplinary perspective(2019)
; ; ; ; ; ; ; ; ; ; ; Several shallow landslides occurred at La Fossa cone (Vulcano Island, Aeolian Archipelago, Italy) in the last 30 years, during both unrests and periods of quiet volcanic activity. The main event occurred in 1988, during a volcanic unrest, when a landslide collapsed into the sea from the NE flank of La Fossa cone, producing a small tsunami. Hydrothermal activity has been suggested as a potential trigger for landslide generation in this area. However, no specific investigations were carried out to test this hypothesis. With the aim of filling this gap, we studied the mineralogy and hydraulic conductivity of La Fossa cone deposits, the relationships between shallow hydrothermal circulation and rainfall dynamics and their role in triggering slope failures. We also measured rainfall rate, volumetric soil moisture content and soil suction at two automated stations installed in areas with and without active hydrothermal circulation.We found that hydrothermally altered low-conductivity materials show higher background water contents and lower soil suctions than pristine deposits, and their water content is modulated by impulsive increments following rainfalls. This behaviour is due to the combination of lower permeability and direct condensation of hydrothermal vapour. We conclude that shallow hydrothermal circulation produces conditions for slope failures following transients in soil moisture content caused by rainfall infiltration. These considerations allow to identify the areas immediately NWand SE of the 1988 landslide as the most prone to future mass movements.216 8 - PublicationOpen AccessGeochemistry and mineralogy of a complex sedimentary deposit in the alkaline volcanic Lake Specchio di Venere (Pantelleria Island, south Mediterranean)Specchio di Venere is a peculiar, ambient temperature, geothermal, alkaline lake, with lake water oversaturated in carbonate phase where siliceous stromatolites actively grow despite the undersaturation of silica phases. The most of the main sedimentary structures of this lake have been investigated in recent years, with the exception of the carbonate bank running along the southwestern margin of the lake, which is the object of this study. Here we report on the mineralogical and geochemical characterisation of the carbonate bank, based on the study of two cores taken in the area mostly affected by the circulation of fluids of different origin. The ultimate results of our study suggest that silica gel deposits form inside the carbonate bank, following an Alkali-Silica Reaction. These new findings complete the general overview on the sedimentary processes acting in a Lake Specchio di Venere, whose origin is sometimes chemico-physical and sometimes strongly conditioned by microbial activity.
151 30