About 150 circular, sub-circular or elongate high back-scattering patches have been identified on... more About 150 circular, sub-circular or elongate high back-scattering patches have been identified on the crest and inner part of the Mediterranean Ridge accretionary complex by means of 6.5 kHz GLORIA long-range side-scan sonar. Some of the patches occur in groups or in ridge parallel alignments, associated with deep-seated structures. On the basis of core stratigraphy they have been interpreted as
Decay of rocks, due both to extrinsic and intrinsic factors, can show up in several different for... more Decay of rocks, due both to extrinsic and intrinsic factors, can show up in several different forms, such as neoformation of minerals, decohesion of grains and/or crystals, magnification of previous defects, new discontinuities, etc. Intrinsic factors include the type of material, its properties and microstructure, in particular porosity and microporosity. Extrinsic factors relate to atmosphere and usage of the material itself. Rock degradation has several heavy consequences for commercial stones, such as increase of permeability, loss of material, loss of mechanical strength; these consequences are of crucial importance for conservation of historical buildings. Aim of this study is to compare microporosity of some massive commercial stones by means of X ray microtomography, a non destructive technique, and Hg porosimetry. Nine of the most used Spanish limestones and dolostones have been analysed. The lithotypes have been chosen for their homogeneous mineralogical composition (calci...
Thirty-one piston and/or gravity cores not exceeding 10 m in length were raised in selected areas... more Thirty-one piston and/or gravity cores not exceeding 10 m in length were raised in selected areas of a 300 km-long transect (Medriff Corridor) crossing the Mediterranean Ridge, an accretionary complex subject to continent/continent collision, containing an important evaporitic body (Messinian evaporites), in order to ground-truth the geological make-up. Core location, very accurate with reference to a complex bottom configuration, was preceded by swathe mapping, seismic profiling and side-scan sonar investigations. Most sediment cores have a pelagic facies, with biogenic marls as dominant lithology, and sapropels and tephras as minor, isochronous lithologies. A combination of isochronous lithologies and calcareous plankton biochronology permits high resolution stratigraphic correlations. Pelagic facies sediments are Middle Pleistocene to Holocene in age. Two cores associated with mounds located along thrusts contain a matrix-supported mud breccia of deep provenance, Burdigalian-Lang...
Landslide dams (i.e., the natural blockage of river channels by hillslope-derived mass movements ... more Landslide dams (i.e., the natural blockage of river channels by hillslope-derived mass movements ) are common natural phenomena with great relevance for geomorphological conditions and for the safety of people living close to them. Landslide dams can induce significant geomorphic hazards in the adjacent areas. Flooding by impounded water can create large lakes in the upstream areas, causing damages to human activities. Catastrophic outburst floods and/or debris flows can be triggered by a rapid dam failure with exceptional rates of sediment erosion and deposition along the downstream part of the valley.
Le dinamiche idrogeologiche lungo i versanti montani rivestono grande interesse per problematiche... more Le dinamiche idrogeologiche lungo i versanti montani rivestono grande interesse per problematiche di primaria importanza quali l'innesco di fenomeni superficiali di instabilità e la generazione di piene. I fattori determinanti comprendono lo spessore del suolo e dei livelli di terreno sciolto, la pendenza e la morfologia del basamento roccioso, le caratteristiche idrogeologiche sia nella zona vadosa che nel saturo, oltre che la tipologia e l'intensità delle precipitazioni.
ABSTRACT Volcanic rocks are widespread in different geological contexts and exhibit complex behav... more ABSTRACT Volcanic rocks are widespread in different geological contexts and exhibit complex behaviors, from hard to extremely soft rocks, depending on mineralogy, porosity, and weathering. In particular, their mechanical properties are influenced by the size and shape of pores. We report the results of porosity characterization by different techniques, performed on lavas with different degrees of alteration, sampled in the Campi Flegrei area (Italy) and characterized through petrographic analyses. Bulk-specific weight measurements, water immersion and Hg-porosimetry gave total and interconnected porosity values. Analysis of thin sections provided 2D pore size and shape estimates and insight in pore relationships with rock matrix and weathering. X-ray Computer Tomography allowed complete 3D reconstruction of rock pores. Different image processing methods for data extraction and analysis have been used to develop a standard analysis procedure. Results in terms of measured porosity and pore size and shape distributions obtained by different techniques are discussed.
Physical properties of some weathered/altered volcanic rocks and their variation with the degree ... more Physical properties of some weathered/altered volcanic rocks and their variation with the degree of alteration are described in detail. A series of tests was performed to identify and quantify the progressive degradation of the properties: 1) petrographycal and chemical studies; 2) effective (η e ) and total porosity (η t ) measurements and 3D pore reconstruction 3) ultrasonic pulse velocity and spatial attenuation (α s ) measurements. Four different volcanic lithologies have been tested: i) trachytic lava with abundant crystals; ii) pyroclastic deposits, with lava clasts and pumice elements; iii) green tuff, made prevalently of pumice clasts; and iv) non-welded ignimbrite deposits. Chemical indices of weathering (CIW) reveal large differences (42.73b Chemical Index of Alteration [CIA]b 69.24) not only between lithotypes, but also between samples. These differences are reflected by physical properties, in particular η t (6.0b η t from X-ray tomography imagesb 49.8%), η e (11.0b η e from mercury porosimeterb 65.0%) and shear wave velocity values (0.50b V s b 2.90 km/s). Pore network evolution with alteration for each lithology is well documented by fractal dimension (D) and α s . Mean values of porosity are strictly related to P and S wave velocity (V p and V s ) and the degree of alteration. Values of CIA are well correlated with the degradation trend exhibited by measured physical properties. The combination of techniques to measure the η t and η e provides a good estimate of grain size and pore size distribution and rock structure. Defects and particular characteristics in the rock sample (e.g. micro-fractures, voids, cavities and orientation and sizes of certain minerals and clasts) are revealed by α s values: the smaller the α s the more homogeneous and less altered is the sample.
The aim of this work was the characterization, using several analytical techniques, of a sample o... more The aim of this work was the characterization, using several analytical techniques, of a sample of ancient pottery found during archaeological excavations in the 14th century's Sforza Castle in Milano. The use of a multi-analytical approach is well established in the study of archaeological materials (e.g. Tite et al. 1984, Ribechini et al. 2008). The chemical composition of the sample
1] Grain size data from the deposit of the 1987 Val Pola rock avalanche (central Italian Alps) ar... more 1] Grain size data from the deposit of the 1987 Val Pola rock avalanche (central Italian Alps) are compared with data concerning rock avalanching, rock fragmentation, and comminution. The Weibull distribution fits a small part of the entire particle-size distribution of debris samples, with a mean value of the curve shape factor of 0.54 ± 0.28. This is typical of multiple comminution, or fragmentation with much shearing. A fractal distribution fits over a greater size range. Computed fractal dimensions range between 1.3 and 3.2 within the deposit, with average values of about 2.6-2.7. These values cover the range between the theoretical values of the plane-of-weakness model (1.97) and the pillar-of-strength model (2.84) and are close to the theoretical value for the constrained comminution model (2.58). These suggest that both texturally mature and immature deposits are present and that more than a single comminution process acted during the rock avalanche motion. Variation of the grain size distribution within the deposit and grain size segregation show as trends in the fractal dimension and arise from variation in the fragmentation process. A variety of different physical and empirical laws suggest that 1-30% of the energy expended in the rock avalanche was consumed in fragmentation.
A saline tracer test has been performed at an industrial site, located in the Po River delta regi... more A saline tracer test has been performed at an industrial site, located in the Po River delta region (North-Eastern Italy). This tracer test was aimed at identifying possible hydraulic connections between a shallow unconfined aquifer and a deeper confined aquifer. Hydraulic head ...
About 150 circular, sub-circular or elongate high back-scattering patches have been identified on... more About 150 circular, sub-circular or elongate high back-scattering patches have been identified on the crest and inner part of the Mediterranean Ridge accretionary complex by means of 6.5 kHz GLORIA long-range side-scan sonar. Some of the patches occur in groups or in ridge parallel alignments, associated with deep-seated structures. On the basis of core stratigraphy they have been interpreted as
Decay of rocks, due both to extrinsic and intrinsic factors, can show up in several different for... more Decay of rocks, due both to extrinsic and intrinsic factors, can show up in several different forms, such as neoformation of minerals, decohesion of grains and/or crystals, magnification of previous defects, new discontinuities, etc. Intrinsic factors include the type of material, its properties and microstructure, in particular porosity and microporosity. Extrinsic factors relate to atmosphere and usage of the material itself. Rock degradation has several heavy consequences for commercial stones, such as increase of permeability, loss of material, loss of mechanical strength; these consequences are of crucial importance for conservation of historical buildings. Aim of this study is to compare microporosity of some massive commercial stones by means of X ray microtomography, a non destructive technique, and Hg porosimetry. Nine of the most used Spanish limestones and dolostones have been analysed. The lithotypes have been chosen for their homogeneous mineralogical composition (calci...
Thirty-one piston and/or gravity cores not exceeding 10 m in length were raised in selected areas... more Thirty-one piston and/or gravity cores not exceeding 10 m in length were raised in selected areas of a 300 km-long transect (Medriff Corridor) crossing the Mediterranean Ridge, an accretionary complex subject to continent/continent collision, containing an important evaporitic body (Messinian evaporites), in order to ground-truth the geological make-up. Core location, very accurate with reference to a complex bottom configuration, was preceded by swathe mapping, seismic profiling and side-scan sonar investigations. Most sediment cores have a pelagic facies, with biogenic marls as dominant lithology, and sapropels and tephras as minor, isochronous lithologies. A combination of isochronous lithologies and calcareous plankton biochronology permits high resolution stratigraphic correlations. Pelagic facies sediments are Middle Pleistocene to Holocene in age. Two cores associated with mounds located along thrusts contain a matrix-supported mud breccia of deep provenance, Burdigalian-Lang...
Landslide dams (i.e., the natural blockage of river channels by hillslope-derived mass movements ... more Landslide dams (i.e., the natural blockage of river channels by hillslope-derived mass movements ) are common natural phenomena with great relevance for geomorphological conditions and for the safety of people living close to them. Landslide dams can induce significant geomorphic hazards in the adjacent areas. Flooding by impounded water can create large lakes in the upstream areas, causing damages to human activities. Catastrophic outburst floods and/or debris flows can be triggered by a rapid dam failure with exceptional rates of sediment erosion and deposition along the downstream part of the valley.
Le dinamiche idrogeologiche lungo i versanti montani rivestono grande interesse per problematiche... more Le dinamiche idrogeologiche lungo i versanti montani rivestono grande interesse per problematiche di primaria importanza quali l'innesco di fenomeni superficiali di instabilità e la generazione di piene. I fattori determinanti comprendono lo spessore del suolo e dei livelli di terreno sciolto, la pendenza e la morfologia del basamento roccioso, le caratteristiche idrogeologiche sia nella zona vadosa che nel saturo, oltre che la tipologia e l'intensità delle precipitazioni.
ABSTRACT Volcanic rocks are widespread in different geological contexts and exhibit complex behav... more ABSTRACT Volcanic rocks are widespread in different geological contexts and exhibit complex behaviors, from hard to extremely soft rocks, depending on mineralogy, porosity, and weathering. In particular, their mechanical properties are influenced by the size and shape of pores. We report the results of porosity characterization by different techniques, performed on lavas with different degrees of alteration, sampled in the Campi Flegrei area (Italy) and characterized through petrographic analyses. Bulk-specific weight measurements, water immersion and Hg-porosimetry gave total and interconnected porosity values. Analysis of thin sections provided 2D pore size and shape estimates and insight in pore relationships with rock matrix and weathering. X-ray Computer Tomography allowed complete 3D reconstruction of rock pores. Different image processing methods for data extraction and analysis have been used to develop a standard analysis procedure. Results in terms of measured porosity and pore size and shape distributions obtained by different techniques are discussed.
Physical properties of some weathered/altered volcanic rocks and their variation with the degree ... more Physical properties of some weathered/altered volcanic rocks and their variation with the degree of alteration are described in detail. A series of tests was performed to identify and quantify the progressive degradation of the properties: 1) petrographycal and chemical studies; 2) effective (η e ) and total porosity (η t ) measurements and 3D pore reconstruction 3) ultrasonic pulse velocity and spatial attenuation (α s ) measurements. Four different volcanic lithologies have been tested: i) trachytic lava with abundant crystals; ii) pyroclastic deposits, with lava clasts and pumice elements; iii) green tuff, made prevalently of pumice clasts; and iv) non-welded ignimbrite deposits. Chemical indices of weathering (CIW) reveal large differences (42.73b Chemical Index of Alteration [CIA]b 69.24) not only between lithotypes, but also between samples. These differences are reflected by physical properties, in particular η t (6.0b η t from X-ray tomography imagesb 49.8%), η e (11.0b η e from mercury porosimeterb 65.0%) and shear wave velocity values (0.50b V s b 2.90 km/s). Pore network evolution with alteration for each lithology is well documented by fractal dimension (D) and α s . Mean values of porosity are strictly related to P and S wave velocity (V p and V s ) and the degree of alteration. Values of CIA are well correlated with the degradation trend exhibited by measured physical properties. The combination of techniques to measure the η t and η e provides a good estimate of grain size and pore size distribution and rock structure. Defects and particular characteristics in the rock sample (e.g. micro-fractures, voids, cavities and orientation and sizes of certain minerals and clasts) are revealed by α s values: the smaller the α s the more homogeneous and less altered is the sample.
The aim of this work was the characterization, using several analytical techniques, of a sample o... more The aim of this work was the characterization, using several analytical techniques, of a sample of ancient pottery found during archaeological excavations in the 14th century's Sforza Castle in Milano. The use of a multi-analytical approach is well established in the study of archaeological materials (e.g. Tite et al. 1984, Ribechini et al. 2008). The chemical composition of the sample
1] Grain size data from the deposit of the 1987 Val Pola rock avalanche (central Italian Alps) ar... more 1] Grain size data from the deposit of the 1987 Val Pola rock avalanche (central Italian Alps) are compared with data concerning rock avalanching, rock fragmentation, and comminution. The Weibull distribution fits a small part of the entire particle-size distribution of debris samples, with a mean value of the curve shape factor of 0.54 ± 0.28. This is typical of multiple comminution, or fragmentation with much shearing. A fractal distribution fits over a greater size range. Computed fractal dimensions range between 1.3 and 3.2 within the deposit, with average values of about 2.6-2.7. These values cover the range between the theoretical values of the plane-of-weakness model (1.97) and the pillar-of-strength model (2.84) and are close to the theoretical value for the constrained comminution model (2.58). These suggest that both texturally mature and immature deposits are present and that more than a single comminution process acted during the rock avalanche motion. Variation of the grain size distribution within the deposit and grain size segregation show as trends in the fractal dimension and arise from variation in the fragmentation process. A variety of different physical and empirical laws suggest that 1-30% of the energy expended in the rock avalanche was consumed in fragmentation.
A saline tracer test has been performed at an industrial site, located in the Po River delta regi... more A saline tracer test has been performed at an industrial site, located in the Po River delta region (North-Eastern Italy). This tracer test was aimed at identifying possible hydraulic connections between a shallow unconfined aquifer and a deeper confined aquifer. Hydraulic head ...
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