A conceptual hydrogeological model of ophiolitic aquifers (serpentinised peridotite): The test example of Mt. Prinzera (Northern Italy)

The main aim of this study is the experimental analysis of the hydrogeological behaviour of the Mt. Prinzera ultramafic massif in the northern Apennines, Italy. The analysed multidisciplinary database has been acquired through (a) geologic and structural survey; (b) geomorphologic survey; (c) hydrogeological monitoring; (d) physico‐chemical analyses; and (e) isotopic analyses. The ultramafic medium is made of several lithological units, tectonically overlapped. Between them, a low‐permeability, discontinuous unit has been identified. This unit behaves as an aquitard and causes a perched groundwater to temporary flow within the upper medium, close to the surface. This perched groundwater flows out along several structurally controlled depressions, and then several high‐altitude temporary springs can be observed during recharge, together with several perennial basal (i.e., low altitude) springs, caused by the compartmentalisation of the system because of high‐angle tectonic discontinuities.     

Infrared interferometry with single telescopes

We examine the merits of three basic interferometric techniques using two-dimensional infrared arrays: speckle interferopmetry, pupil plane interferometry, and speckle holography.Paper presented at the Symposium on the JNLT and Related Engineering Developments, Tokyo, November 29–December 2, 1988.     

Infrared companions to pre-main sequence stars

Summary We report 1.2, 1.6, 2.2 and 3.6 μm slit scan observations of the young low-luminosity stars Elias 22 (also known as GSS 31) in the Rho Ophiuchus dark cloud and Glass I in the Chamaeleon dark cloud. We discovered an infrared companion to Elias 22 at a projected separation of 2.0 arcsec (320 AU) and an optical/infrared companion to Glass I at a projected separation of 2.9 arcsec (410 AU). The companion of Elias 22 is a very cool optically almost invisible object (∼1000 K) less luminous than the primary, while the companion to Glass I is an optically visible late-type star with an infrared excess so large that it is actually bolometrically brighter than the primary. In both cases the infrared excess is likely to be due to hot circumstellar dust grains heated by a central young star (much more obscured in the case of Elias 22 than in the case of Glass I). We outline a new method to determine the mass ratio of such systems assuming that both components lie on an isochrone in the H-R diagram. If the companions are in a bound orbit, the estimated specific angular momentum exceeds or is of the order of 10²¹ cm² s⁻¹, only one order of magnitude larger than that of the Sun-Jupiter system. Based on observations collected at the European Southern Observatory at La Silla, Chile.     

Long-term growth and metropolitan spatial structures: an analysis of factors influencing urban patch size under different economic cycles

Urban forms are increasingly reflective of socio-economic change in metropolitan regions. The present study illustrates an original approach to identify latent mechanisms of urban growth through the analysis of metropolitan spatial structures and their proximate drivers of change. Urban transformations are evaluated here using built-up patches as the elementary analysis unit and background socio-economic attributes at four stages of the “city life cycle” (urbanization, suburbanization, dis-urbanization, re-urbanization). Regression models based on 13 indicators assessing urban patch area and shape, nearest neighbour urban patch area and shape, elevation, distance from 5 urban centres, 2 road infrastructures and sea coastline, were run with the aim to investigate direction and intensity of metropolitan growth in post-war Athens (1948–2012), a southern European city shifting from a compact mono-centric form towards discontinuous urban structures. Mono-centric configurations were characterized by linear dependence of urban patch size from the distance to central cities. Shifts toward scattered urban forms were associated with changes in the multivariate relationship between urban patch size and territorial drivers, pointing out the increased complexity of dispersed metropolitan structures. Our approach integrates economic and ecological visions of urban landscapes and contributes to understanding long-term mechanisms of metropolitan growth under dynamic spatial equilibriums. Investigating the multiple relationships between form and functions at the base of socio-economic transformations are relevant issues when identifying and profiling urbanization cycles.     

Field investigations and monitoring as tools for modelling the Rossena castle landslide (Northern Appennines, Italy)

In the evening of February 28, 2004, a landslide took place in the village of Rossena (Northern Apennines, Italy), built at the base of a crag shaped in a basalt mass and wrapped in highly deformed formation of clay and shale with blocks. The failure damaged some houses, roads and fields but, fortunately, the medieval Rossena Castle, lying on the crag, was not involved at all. The goal of the study was to attain a technical and geological model of the slope to generate a landslide risk zonation, for regularity and development planning, so that the most correct action plans could be proposed. A detailed geological and geomorphological survey allowed for distinguishing the different gravitative landform of this area. It was very helpful to plan direct and indirect investigation, including borehole drillings, samplings, seismic (tomography), and electrical surveys. A monitoring system was built up immediately after the event (three wire extensometers and one inclinometer), then progressively substituted by a more complete one (two tiltmeters, two jointmeters, four inclinometers, two incremental extensometers, and two piezometers). The phenomenon can be divided in different parts. The central sector of the slope is interested by compound slides likely affecting the bedrock and can be considered, at present, the ‘engine’ of the whole instability framework. Indeed, as a consequence, in the upper portion of the slope the huge blocks in which the outer part of the crag is disjointed experienced vertical displacements and, locally, topplings. Finally, the lowest sector is affected by slow movements, probably connected to bedrock creep or rock flow, while the toe, really at the foot of the slope, by shallow landslides. This instability framework is the result of a complex evolution, starting almost more than 9,000 years ago, as testified from a radiocarbon dating. In more recent time (19th century), the Rossena landslide was also triggered by an earthquake that induced the partially breaking up of the crag, causing rock falls and cracks in the ground.     

Landslides types controlled by tectonics-induced evolution of valley slopes (Northern Apennines,Italy)

This paper investigates the role played by geomorphological and tectonic processes affecting a portion of an active mountain belt in causing the occurrence of different types of landslides developed in flysch bedrock. The adopted multidisciplinary approach (geomorphology, geology and geophysics) allowed to recognize in a portion of the Northern Apennines of Italy different types of landslides that developed in response to slope dynamics, in turn dependent on broader regional-scale tectonic processes. Sedimentary bed attitude, local tectonic discontinuities and lithology only partially influenced the type of landslides, which have been deeply affected by the activity of regional-scale antiform that controlled the hillslope geomorphic evolution in different ways. The growth of this structure and the tilting of its forelimb produced gently dipping slopes that approached the threshold angle that can cause the occurrence of (mainly) translational rockslides. Conversely, high-angle normal faulting parallel to the antiform axis (related to a later stage of activity of the antiform itself) strongly controlled the stream network evolution and caused the watercourses to deeply incise portions of their valleys. This incision produced younger steep valley slopes and caused the development of complex landslides (roto-translational slides-earth/debris flow). The results of the integrated study presented in this paper allowed to distinguish two main types of landslides whose development reflects the events that led to the geomorphological and geological evolution of the area. In this perspective, within the study area, landslides can be regarded and used as indicators of broader-scale recent tectonic processes.     

Adaptation of the Canadian Fire Weather Index to Mediterranean forests

Natural Hazards - The Canadian Fire Weather Index (FWI) is one of the most used tools to forecast forest fire hazard. In this paper, we propose an adaptation of the FWI to take into account the...     

Geoarchaeological sea-level proxies from a silted up harbour: A case study of the Roman colony of Luni (northern Tyrrhenian Sea, Italy)

The Luni Plain, which faces the northern Tyrrhenian Sea, underwent major landscape changes over the last 3000 years. The coastline shifted south and west, separating the ruins of the ancient Roman colony of Luni (founded in 177 BC) from the sea by means of a new coastal plain. The precise location of the coastline during the main settlement phase as well as during the city's decline has never been established, although partial and qualitative scenarios have been suggested by various authors. According to these authors, an indentation of the coastline west of the city formed a major water basin, along the shores of which traces of pre-Roman settlements exist; near the city, two minor basins were present, suitable for hosting harbour structures. The city of Luni was famed for its harbour (Portus Lunae), from which the marbles quarried in the Apuan Alps, used to build many of the monuments in Rome, were delivered. The traces of its port, however, are scattered and uncertain.Newly available subsurface data are presented, associated with a revision of unpublished archaeological evidence of the ancient city topography. Progress in palaeoenvironmental reconstructions at Luni has been possible thanks to the collection and analysis of ancient and recent cores, supported by radiocarbon dates, as well as the interpretation of archaeological findings suitable as markers for sea-level recognition. The main environmental changes in the area have been refined: since a few centuries before the colony was founded, the Luni plain had been characterized by a complex architecture of swamps and marshes limited by dune ridges and fluvial sand bars. The positions of these landforms were not fixed, but shifted, mainly depending on the spatial relationship between the coastline and the river mouths.Determining the precise position of the Roman coastline is useful to constrain the area in which archaeological surveys should be concentrated in order to identify the harbour location. Moreover, some of these results have been used to infer altitude constraints on the sea-level position in Roman times: preliminary data are shown for constructing a Late Holocene local sea-level curve in the area.     

PEGASE, an infrared interferometer to study stellar environments and low mass companions around nearby stars

PEGASE is a mission dedicated to the exploration of the environment (including habitable zone) of young and solar-type stars (particularly those in the DARWIN catalogue) and the observation of low mass companions around nearby stars. It is a space interferometer project composed of three free flying spacecraft, respectively featuring two 40 cm siderostats and a beam combiner working in the visible and near infrared. It has been proposed to ESA as an answer to the first “Cosmic Vision” call for proposals, as an M mission. The concept also enables full-scale demonstration of space nulling interferometry operation for DARWIN.

Relationships between glacier and rock glacier in the Maritime Alps, Schiantala Valley, Italy

In the Schiantala Valley of the Maritime Alps, the relationship between a till-like body and a contiguous rock glacier has been analyzed using geomorphologic, geoelectric and ice-petrographic methodologies. DC resistivity tomographies undertaken in the till and in the rock glacier show the presence of buried massive ice and ice-rich sediments, respectively. Ice samples from a massive ice outcrop show spherical gas inclusions and equidimensional ice crystals that are randomly orientated, confirming the typical petrographic characteristics of sedimentary ice. The rock glacier formation began after a phase of glacier expansion about 2550 ± 50 ¹⁴C yr BP. Further ice advance during the Little Ice Age (LIA) overrode the rock glacier root and caused partial shrinkage of the pre-existing permafrost. Finally, during the 19th and 20th centuries, the glacial surface became totally debris covered. Geomorphological and geophysical methods combined with analyses of ice structure and fabric can effectively interpret the genesis of landforms in an environment where glaciers and permafrost interact. Ice petrography proved especially useful for differentiating ice of past glaciers versus ice formed under permafrost conditions. These two mechanisms of ice formation are common in the Maritime Alps where many sites of modern rock glaciers were formerly occupied by LIA glaciers.