Gilberto Pambianchi

Geomorphological evidence for anti-Apennine faults in the Umbro-Marchean Apennines and in the peri-Adriatic basin, Italy

Abstract The Apennines are a relatively recent mountain chain which has been affected by uplift movements since the Upper Pliocene. In fact the remnants of an “erosional surface”, reduced close to base level, is preserved at the top of the relief. There is no general agreement on the geodynamic stress field and mechanisms which are creating the chain. However, it is largely accepted that uplift occurred together with the activation, on the western side of the chain, of extensive faults, oriented in the Apennine direction (NW-SE), which have been linked to the opening of the Tyrrhenian sea. A great debate is going on about the presence and significance of anti-Apennine faults (NE-SW) which have been observed by some authors but completely denied by others. The main evidence is represented by[ (1) block faulting of the remnants of the “erosional surface”. Along the Marchean Ridge, more elevated relief, delimiting relatively depressed areas, was created in correspondence with the Sibillini Mts. and Mt. S. Vicino. Similar evidence has been found in the Umbro-Marchean Ridge. Locally more than 1500 metres of displacement have been observed between more and less uplifted remnants. (2) Block faulting of fan deltas and related beaches, of Sicilian to Crotonian age, with more elevated sediments preserved between the Tronto and Tenna rivers and between the Musone and Esino rivers. Maximum displacement along a transect parallel to the coast is 200 metres. (3) fault-scarps affecting the Middle Pleistocene river terraces, as observed along the Esino, the Tronto, the Chienti and the Tenna river valleys. Maximum displacements are in the order of 50 metres. (4) Faulting of horizontal karst galleries and reorientation of the cave network, as in the Frasassi Gorge. Maximum displacements are about 100 metres. (5) Captures and alignments in the drainage network of the main river courses. (6) Large-scale gravitational movements, as in the Ancona landslide, and along the Chienti and Esino rivers. Their activation occurred in most cases after the Lower Pleistocene and although their displacements may be of relatively limited extent, dispite their recent activity, they played a major role in the modelling of the landscape. These faults display transtensive, extensional and trascurrent movements. Apart from the controversial geodynamic significance of these faults, from a geomorphological point of view they must be considered transverse elements of the stress field from blocks more or less uplifted along the Apennine chain. The importance and timing of activity of these faults in the Quaternary geomorphological evolution of the Umbria-Marchean Apennines is demonstrated using evidence usually underestimated by structural geologists, which can contribute to a debate based on a multidisciplinary approach.

Relief, Intermontane Basins and Civilization in the Umbria-Marche Apennines: Origin and Life by Geological Consent

The landscape of the Umbria-Marche Apennines (Central Italy) shows a rhythmic sequence of “whaleback” anticlinal ridges separated by longitudinal synformal valleys. In this topographic arrangement, flat-floored tectonic depressions appear which enclose a wide range of landforms, and witness the continuous balance between tectonic forces, Quaternary climatic phases and drainage network adjustment. Fault scarps and triangular facets characterize the bordering slopes where thick talus deposits and landslides highlight the gravitational component. Karstic landforms as dolines and caves and fluvial features testify to the action of water. The resulting landscape is, for a visitor, like an incomparable geological handbook.

Analysis of mountain springs discharge time series in the Tennacola stream catchment (central Apennine, Italy)

The mountain portion of the Tennacola stream basin, which is located in the northeast sector of the Sibillini Mountains (Central Apennines, Italy), has a large number of springs exploited for drinking water. The presence of lithotypes with different hydraulic conductivity allowed the formation of two main groups of springs with different discharge and regime. This paper aims to provide new insights about the groundwater circulation within carbonate and karst complexes. In detail a study based on spring hydrograph analysis using the MRC method and on the main statistical parameters has been carried out, in order to evaluate the main features related to the flow paths and the main hydrogeological properties of the aquifers studied. The results allowed to characterize the main hydrogeological features of the aquifers and to evaluate the dimension of the recharge areas.

Groundwater recharge estimation using spring hydrographs: the case of the Tennacola carbonate aquifer (central Apennine, Italy)

The recharge of an aquifer is fundamental to evaluate the availability of the resource and for planning its use over the time.In general, indirect methods are widely used, because these are based on the rainfall, evapotranspiration and runoff data. These three parameters are not always simple to evaluate in relation to the possible presence of errors in the available data, malfunction of instruments or difficulty to make a monitoring in relation to the complexity of the area, with consequent uncertainty on the results. In such situations, the use of a direct method could be useful to estimate more accurately the aquifer recharge.A common direct method is based on the analysis of the spring hydrographs, i.e. the discharge monitored at the spring. In this work, a spring hydrograph from the central Apennines of Italy has been analysed in order to estimate the average recharge value feeding the aquifer.

DSGSDs Induced by Post-Glacial Decompression in Central Apennine (Italy)

During the last 30 years of studies in the field of mass movements located in the calcareous-marly and marly-sandy Apennines (Umbria-Marches and Latium-Abruzzi regions), over to a large number of landslides with different dimensions, even a lot of deep-seated gravitational slope deformations (DSGSDs) have been recognized and analysed. These phenomena are also located in that sector of central Italy affected by a cold climate during the past and actually temperate (central Apennine chain).

Pliocene-Pleistocene geomorphological evolution of the Adriatic side of central Italy

Abstract This work is a significant contribution to knowledge of the Quaternary and pre-Quaternary morphogenesis of a wide sector of central Italy, from the Apennine chain to the Adriatic Sea. The goal is achieved through a careful analysis and interpretation of stratigraphic and tectonic data relating to marine and continental sediments and, mostly, through the study of relict limbs of ancient landscapes (erosional surfaces shaped by prevailing planation processes). The most important scientific datum is the definition of the time span in which the modelling of the oldest morphological element (the “summit relict surface”) occurred: it started during Messinian in the westernmost portion and after a significant phase during middle-late Pliocene, ended in the early Pleistocene. During the middle and late Pleistocene, the rapid tectonic uplift of the area and the climate fluctuations favoured the deepening of the hydrographic network and the genesis of three orders of fluvial terraces, thus completing the fundamental features of the landscape. The subsequent Holocene evolution reshaped the minor elements, but not the basic ones.

Application of the MRC method to the study of some mountain springs in the Tennacola stream catchment (central Apennine, Italy)

The study concerns part of the plain sector of Aosta Valley (NW Italy). The investigated area is located between the cities of Sarre-Gressan and Pollein-Saint Christophe and is characterized by the presence of hexavalent chromium in the main shallow unconfined aquifer. The pollution is probably related to the negative environmental effects induced by the industrial steel production that since 1915 is present over the area. Since 1990 the industrial area was subjected to a number of direct investigations aimed to assess the contamination intensity. A preliminary remediation activity has been developed in last decades but the contaminants have been still observed in the groundwater monitoring network. This study highlights the set-up of a groundwater conceptual and numerical model of the shallow aquifer aimed to better understand and analyze the transport dynamics of hexavalent chromium in the local aquifer. The simulation is performed using the specific finite element software Feflow for groundwater flow and mass transport modeling. The hydrogeological setting of this area is related to the different sedimentary glacial, lacustrine and fluvial processes which characterized the bottom of the Aosta valley during the Quaternary. The shallow 80m-width aquifer is constituted by sandy to gravelly deposits and presents rare silty lens while its bottom is characterized by a decametric lacustrine silty level. The main aims of the numerical model are to give a more unequivocal explanation of the origin of the contamination and to support the predictive analyses in order to design an efficient site remediation for soil and groundwater. This represents a fundamental task in order to preserve the safety of the public water uses supplied by the aquifer. The preliminary hypothesis about the source of contaminations are still uncertain and referred to different scenarios that have to be further investigated by comparing monitoring data and transient flow simulation conditions.

Hazard assessment of a complex landslide: the case of Vestea (Abruzzo, Italy)

This short note aims to reconstruct the geomorphological hazard scenarios connected to the complex landslide that insists on the territory of Vestea (Civitella Casanova Municipality, in the province of Pescara, Italy). The landslide, active for several decades, probably since the XIX century, is located along a wide valley and starting from its head. It manifests frequently local reactivations with varying movement typology; while total reactivations, taking place in concomitance of particular climate and hydrogeological factors, are more rare.

Deep Seated Gravitational Slope Deformations and Large Landslides Interfering with Fluvial Dynamics; Examples from Central Apennines (Italy)

The study, developed over a wide mountain sector of the central Apennines (Italy), highlights the role of Deep Seated Gravitational Slope Deformations (DSGSD) in the evolution of a mountain portion of the Chienti river valley. Radiocarbon dating and geomorphological considerations, testify that a lateral spreading, developed on a large scale, has triggered large landslides in correspondence of the thalweg. These phenomena have repeatedly dammed the river bed (certainly since the end of the late Pleistocene) creating temporary lakes which lasted also for a long time. The high seismicity and the persistence of conditions favorable to the development of gravitational phenomena, in an area currently occupied by an important communication route, attest to the high degree of risk present in this sector of the Apennine.

Geomorphological Hazard in Hypogeum Karst Touristic Landscape: An Example from Frasassi Cave (Central Italy)

The study of geomorphological hazards in tourist areas has been addressed only recently, mostly because in areas of high touristic value any risk for excursionists or for simple nature lovers represents a strong conditioning factor to the fruition and therefore to the economy of an entire area. The geomorphological hazard can turn into a considerable risk, if one takes into account the increasing human pressure even in remote areas. The development of tourism, in fact, brings an increasing number of people to discover and attend both areas prone to hazards for some time, both in areas where these hazards are being increased. The complexity and multiplicity of these changes require necessarily a greater attention not only for a correct comprehension of natural phenomena but mostly for their possible interactions with tourism attendance and fruition. Based on previous experiences, also as a result of research projects funded by the Italian Ministry for the University and the Research (MIUR). A study on the natural hazards related to the touristic fruition in the area of Frasassi Cave in the Marche region (central Italy) is following presented.