Archaeological and historiographical implications of recent uplift of the Peloro Peninsula, NE Sicily

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 To address this discrepancy, geomorphologic data were collected and analyzed to verify whether historical documents were consistent with the palaeotopography of the area.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.     

Computing the flux of moisture from net radiation and soil wetness

A study has been made of the time evolution of the flux of moisture E over grassland. The parameterization of E has been examined in order to formulate an equation depending on the net radiation flux and on bulk parameters which depend on the daily average meteorological situation and soil conditions. In particular the gradient of soil moisture has been recognized as playing a fundamental role in the time evolution of E(t). A time-dependent equation is proposed to compute in a statistical sense the irrigation needs or to forecast the hourly values of E(t), the maximum value E ₀ and the time at which this maximum happens.     

Coupled degassing and crystallization: experimental study at continuous pressure drop, with application to volcanic bombs

 Experiments on degassing of water-saturated granite melts with a pressure drop from 100 and 450 MPa to 40 and 120 MPa, respectively, at temperatures close to feldspar liquidus (750–700  °C), were carried out to determine the modality of water exsolution and vesicle formation at the liquidus temperature. Pressure-drop rates as small as approximately 100 bar/day were used. Uniform space distributions of bubbles of exsolved water were obtained with starting glass containing a small fraction (≈0.5 vol.%) of trapped air bubbles. Volume crystallization of feldspar was observed in degassed melts supplied with seeds. Bubble size distributions (BSD) measured in granite glasses after degassing are presented. Data on vesicle characteristics (number, radius, area, elongation) were acquired on images digitized with standard software, while the reconstruction of size distributions was performed with the Schwartz-Saltikov "unfolding" procedure. Bubble size distributions of size classes in the range 5–1000 μm were acquired with proper magnification and satisfactory statistical reliability of determined number densities. The BSDs of the experimental samples are compared with the results of measurements of rapidly degassed products of Mt. Etna and Vulcano Island. Many particular features of the bubble nucleation and growth can be distinguished in an individual BSD. However, the general BSD of the whole data set, including natural ones, can be relatively well described with linear regression in bilogarithmic coordinates. The slope of this regression is approximately 2.8±0.1. This dependence is in striking contrast with distributions theoretically predicted with classical nucleation models based on homogeneous nucleation of vesicles. The theoretical distribution requires the occurrence of strong maxima that are not observed in our experimental and natural samples, thus arguing for heterogeneous nucleation mechanisms. Received: 1 October 1998 / Accepted: 25 June 1999     

A warning system for rainfall-induced shallow failures

It is widely recognised that soil slips and debris flows are triggered by short intense storms. Owing its geologic, geomorphologic and climatic settings, the Piedmont Region (NW Italy) is highly prone to the occurrence of this kind of landslides. In the last two centuries, in fact, a total of 105 severe meteoric events which triggered shallow failures occurred and, of these, 18 events took place from 1990 to 2002. A fair number of rainfall thresholds have been proposed in the literature, defined both on empirical or on physical bases. Empirical thresholds are defined collecting rainfall data for landslide meteoric events and for events without landslides, while physical thresholds are based on numerical models that consider the relation between rainfall, pore pressure and slope stability. The main objective of this paper is the identification of the empirical triggering thresholds for the Piedmont Region. Four meteoric events were selected and analysed (November 4–5, 1994; July 7–8, 1996; April 27–30, 2000; October 13–16, 2000) because they supply a wide range of variation for both rainfall parameters (duration, intensity, cumulative rainfalls) and the number of induced landslides. In the intensity–duration plot, the critical limit is described by the equation: I=19D^−0.50 (where I=rainfall intensity expressed in mm/h and D=rainfall duration expressed in hours). Such a limit is traced to envelop 90% of the points on the graph. In the NI–D diagram the triggering thresholds are given by the equations NI=0.76D^−0.33 and NI=4.62D^−0.79 (where NI=normalised intensity with respect to the annual precipitation, MAP, expressed in %, [(mm/h)/PMA]×100). In the article the different meaning of these thresholds is discussed. Finally, the diagram NI–NCR is proposed; the triggering threshold is given by the expression: NI=−0.09ln[NCR]+0.54 (where NCR is the normalised cumulative critical rainfall, [mm/PMA]×100). The application of the triggering thresholds as a fundamental element in a warning system dedicated to the safeguarding of population in landslide-prone areas is discussed. In detail an operating procedure which is presently being verified and tested in the studied area is described.     

The ascent of the anthropostrome: A point of view on the man-made environment

The anthropostrome is used to denote the collective constructs of human artifacts and is characterized by repetitive geometrical moduli, centralized energetic cyclons, and constrictive restraints to functional freedom of both human and non-human elements. This unified, self-perpetuating, man-made environment is a high-level integrative structure where organism-like features are developing while ocosystem-like features persist. Due to pervasive integration, urban-industrial men generally fail to perceive the colonial nature of the autonomous unit which produced them Direct contacts with the world outside the anthropostrome are scare, and most information and sensory experience are supplied by the anthropostrome itself In spite of temporary or localized regressions, the global trend is apparently toward growth of the total anthropostrome Expansion of urban systems will presumably be accelerated until environmental degradation and resource shortages act as natural constraints The need for containment of the anthropostrome’s growth and for control of its swift noogentic development while avoiding injury to men is possibly the next challenge to man’s evolutionary potential     

Multitemporal UAV surveys for landslide mapping and characterization

This paper presents the preliminary results of the IPL project 196 “Development and applications of a multi-sensor drone for geohazards monitoring and mapping.” The objective of the project is to test the applicability of a multi-sensor drone for the mapping and monitoring of different types of geohazards. The Department of Earth Sciences of the University of Florence has developed a new type of drone airframe. Several survey campaigns were performed in the village of Ricasoli, in the Upper Arno river Valley (Tuscany, Italy) with the drone equipped with an optical camera to understand the possibility of this rising technology to map and characterize landslides. The aerial images were combined and analyzed using Structure-from-Motion (SfM) software. The collected data allowed an accurate reconstruction and mapping of the detected landslides. Comparative analysis of the obtained DTMs also permitted the detection of some slope portions being prone to failure and to evaluate the area and volume of the involved mass.     

Correction to: A novel methodological approach for land subsidence prediction through data assimilation techniques

Computational Geosciences - A Correction to this paper has been published: https://doi.org/10.1007/s10596-021-10079-6     

Surface flow boundary conditions in modeling land subsidence due to fluid withdrawal

Land subsidence due to subsurface fluid (water, gas, oil) withdrawal is often predicted by either finite element or finite difference numerical models based on coupled poroelastic theory, where the soil is represented as a semi-infinite medium bounded by the traction-free (ground) surface. One of the variables playing a most important role on the final outcome is the flow condition used on the traction-free boundary, which may be assumed as either permeable or impermeable. Although occasionally justified, the assumption of no-flow surface seems to be in general rather unrealistic. A permeable boundary where the fluid pressure is fixed to the external atmospheric pressure appears to be more appropriate. This paper addresses the response, in terms of land subsidence, obtained with a coupled poroelastic finite element model that simulates a distributed pumping from a horizontal aquifer confined between two relatively impervious layers, and takes either a permeable boundary surface, i.e., constant hydraulic potential, or an impermeable boundary, i.e., a zero Neumann flow condition. The analysis reveals that land subsidence is rather sensitive to the flow condition implemented on the traction-free boundary. In general, the no-flow condition leads to an overestimate of the predicted ground surface settlement, which could even be 1 order of magnitude larger than that obtained with the permeable boundary.     

New stratigraphical data on the Middle-Late Jurassic biosiliceous sediments from the Sicanian basin, Western Sicily (Italy)

The reported data present the stratigraphy of several sections across a Middle-Late Jurassic Radiolaritic Unit, well exposed in different thrust sheets pertaining to the Maghrebian chain of Southwestern Sicily. The aim was to define the chronostratigraphical distribution of the Jurassic biosiliceous sedimentation in the Sicanian palaeogeographical zone, a deep water basin belonging to the Southern Tethys continental margin. The radiolarian biostratigraphy indicates that the switching from carbonate to siliceous sedimentation in the Sicanian Basin is referable to the Bajocian, as shown by the section of Campofiorito, near Corleone. The biostratigraphical dataset allows the correlation between the onset of biosiliceous sedimentation and the fall of biodiversity in the Sicanian basin with the carbonate productivity crisis, indicated by the highest eutrophication that affected Western Tethys during Middle Jurassic times. Editorial handling: J.-P. Billon-Bruyat & M. Chiari (Guest)     

Three-dimensional numerical modeling of land subsidence in Shanghai,China

Shanghai, in China, has experienced two periods of rapid land subsidence mainly caused by groundwater exploitation related to economic and population growth. The first period occurred during 1956–1965 and was characterized by an average land subsidence rate of 83 mm/yr, and the second period occurred during 1990–1998 with an average subsidence rate of 16 mm/yr. Owing to the establishment of monitoring networks for groundwater levels and land subsidence, a valuable dataset has been collected since the 1960s and used to develop regional land subsidence models applied to manage groundwater resources and mitigate land subsidence. The previous geomechanical modeling approaches to simulate land subsidence were based on one-dimensional (1D) vertical stress and deformation. In this study, a numerical model of land subsidence is developed to simulate explicitly coupled three-dimensional (3D) groundwater flow and 3D aquifer-system displacements in downtown Shanghai from 30 December 1979 to 30 December 1995. The model is calibrated using piezometric, geodetic-leveling, and borehole extensometer measurements made during the 16-year simulation period. The 3D model satisfactorily reproduces the measured piezometric and deformation observations. For the first time, the capability exists to provide some preliminary estimations on the horizontal displacement field associated with the well-known land subsidence in Shanghai and for which no measurements are available. The simulated horizontal displacements peak at 11 mm, i.e. less than 10 % of the simulated maximum land subsidence, and seems too small to seriously damage infrastructure such as the subways (metro lines) in the center area of Shanghai.