| My geophysical papers with collegues :) |
| Paleoseismological evidence for historical ruptures along the Meduno Thrust (eastern Southern Alps, NE Italy) |
| Poli, ME; Falcucci, E; Gori, S; Monegato, G; Zanferrari, A; Affatato, A; Baradello, L; Bohm, G; Dal Bo, I; Del Pin, E; Forte, E; Grimaz, S; Marchesini, A |
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| We carried out new geological, morphotectonic, geophysical and paleoseismological investigations on the Meduno Thrust that belongs to the Pliocene-Quaternary front of the eastern Southern Alps in Friuli (NE Italy). The study area is located in the Carnic Prealps, where a series of alluvial terraces, linked to both climatic and tectonic pulses characterises the lower reach of the Meduna Valley. In correspondence of the oblique ramp of the Meduno Thrust, the Late Pleistocene Rivalunga terrace shows a set of scarps perpendicular to the Meduno valley, often modified by human activity. In order to reconstruct the tectonic setting of the area and identify the location for digging paleoseismological trenches, integrated geophysical investigations including electrical resistivity tomography, seismic refraction and reflection, ground penetrating radar and surface wave analyses (HVSR, ReMi and MASW), were carried out across the scarps of the Rivalunga terrace. Geophysical surveys pinpointed that in correspondence of the oblique ramp, stress is accommodated by a transpressive thrust system involving all the seismo-stratigraphic horizons apart from the ploughed soil. Trenching illustrated the Meduno Thrust movements during Late Pleistocene-Holocene. Trenches exhibited both shear planes and extrados fracturing, showing deformed alluvial and colluvial units. C-14 datings of the colluvial units show that the most recent fault movements occurred after 1360 CE and 1670 CE. The age of the deformed stratigraphic units compared with the earthquakes listed in current catalogues, suggests that the 1776 earthquake (Mw 5.8, Io = 8-9 MCS) could represent the last seismic event linked to the Meduno thrust activity. This study provided new quantitative constraints improving seismic hazard assessment for Carnic prealpine area. |
| Amplitude Recovery and Deconvolution of Chirp and Boomer Data for Marine Geology and Offshore Engineering |
| Denich, E; Vesnaver, A; Baradello, L |
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The processing of Chirp data is limited by the usual recording of the signal envelope, which enhances its immediate visibility but prevents applying methods based on wave equations. This is normally not the case for Boomer data. However, both systems are monochannel instruments, which cannot estimate properly the propagation velocity of the signal in the rocks. In this paper, we present two theorems: the first one links the Chirp or Boomer source spectrum with an expected amplitude decay curve; the second one defines conditions for the deconvolution stability of the enveloped Boomer signal when the full waveform of the source signal is known. In this way, we can jointly process and integrate heterogeneous surveys including both data types. We validated the proposed algorithms by applying them to synthetic and real data. The presented tools can improve the image resolution and the characterization of geological formations in marine surveys by reflectivity anomalies, which are distorted by standard equalization methods. |
| Fast method to transform chirp envelope data into pseudo-seismic data |
| Baradello, L; Battaglia, F; Vesnaver, A |
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Chirp technology is an acoustic tool for imaging the shallow seabed with a high resolution, used for investigations of modern to Quaternary sedimentary structures and processes and more applied goals, such as hazard surveys for drilling, archeology, geology or engineering fields. In this paper, we present new methods that improve such imaging. During the standard acquisition, the Chirp waveforms are converted into analytic signals and only their envelope is preserved and interpreted, because the highly oscillating signal is otherwise difficult to be identified visually. Doing so, however, the phase information is lost, and the final processing is limited mainly to simple time-varying gain recovery or filtering. We present a work flow including a derivative step to transform the enveloped signal into a seismic-like waveform. In this way, we can apply processing tools as FX deconvolution and migration to improve the signal/noise ratio and reduce diffractions. This method allows reviving standard and legacy Chirp data where the full-waveform information is missing. |
| Depositional setting of the southern arms of Lago Argentino (southern Patagonia) |
| Lozano, J; Donda, F; Bran, D; Lodolo, E; Baradello, L; Romeo, R; Vilasa, JF; Grossi, M; Tassone, A |
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Lago Argentino hosts a series of calving glaciers originating from the Southern Patagonian Icefield, the largest temperate ice cap of the southern hemisphere. Brazo Rico and Brazo Sur are two basins located in the southern part of Lago Argentino, where a series of high-resolution seismic profiles have allowed reconstruction of its depositional setting and sedimentary architecture, and to produce the following maps: top of the acoustic basement, top of the glacial sequence, and thickness of the glacio-lacustrine deposits. Data reveal the role of basement highs in the complex dynamic behavior of the two main glaciers, Perito Moreno and Frias glaciers, which fluctuated along Brazo Rico and Brazo Sur since the end of the Last Glacial Maximum. Their advances and retreats are testified by the presence of several moraine fronts buried beneath a generally undisturbed, glacio-lacustrine and lacustrine sequence, which records the depositional history of the southern arms of Lago Argentino. |
| The submerged footprint of Perito Moreno glacier |
| Lodolo, E; Donda, F; Lozano, J; Baradello, L; Romeo, R; Bran, DM; Tassone, A |
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Perito Moreno is the most famous calving glacier of the South Patagonia Icefield, the largest temperate glacier system of the Southern Hemisphere. Unlike most of the glaciers in the region that have strongly retreated in recent decades, the position of Perito Moreno glacier front remained relatively unchanged in the last century. However, earliest photographic documents show that, at the end of the nineteenth century, the front was ca. 800 m behind the current position. There is no reliable information about the positions of the Perito Moreno front in earlier times. Here we show evidence of two subaqueous moraine systems both in the Canal de Los Tempanos and in the Brazo Rico, the two arms of Lago Argentino along which Perito Moreno glacier has flowed over time. These moraines, identified for the first time in the Canal de Los Tempanos from bathymetric and high-resolution seismic profiles, mark the position of the largest glacier advance, tentatively correlated with the moraines of the "Herminita advance" identified and dated onland. We interpret these bedforms as the evidence of the most pronounced advance of Perito Moreno glacier during the mid-Holocene cooling event that characterized this sector of the Southern Hemisphere. This study highlights the importance of subaqueous glacial bedforms, representing decisive records of the glacial history and palaeoclimate, which could help unveiling the origin of the different behavior of glaciers like Perito Moreno that in a warming climate are relatively stable. |
| An inter-disciplinary and multi-scale approach to assess the spatial variability of ground motion for seismic microzonation: the case study of Cavezzo municipality in Northern Italy |
| Lai, CG; Poggi, V; Fama, A; Zuccolo, E; Bozzoni, F; Meisina, C; Boni, R; Martelli, L; Massa, M; Mascandola, C; Petronio, L; Affatato, A; Baradello, L; Castaldini, D; Cosentini, RM |
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Seismic microzonation represents a basic tool for prevention activity planning and land management. An extensive and detailed microzonation study was performed with reference to the territory of the Municipality of Cavezzo, damaged during the seismic sequence hitting Emilia-Romagna Region, Northern Italy, in 2012. In this paper, we discuss the work carried out to characterize the spatial variability of ground motion amplification due to local soil conditions in the municipality area. An inter- and mull-disciplinary approach is presented, involving geotechnical engineers, geophysicists, geologists and seismologists from different institutions, to thoroughly characterize the territory using complementary techniques with different level of resolution and confidence. A considerable amount of geomorphological, geological, hydrogeological, seismological, geotechnical and geophysical investigations was collected and processed for the purpose. A GIS-based (Geographic Information System) platform was initially setup to manage the gathered data, which now includes the results of about 1000 geotechnical and geophysical tests. Such an extended dataset was then used as a primary constraint for the creation of a comprehensive pseudo-3D geotechnical and seismo-stratigraphic model of the territory, consisting of a dense grid of one-dimensional vertical profiles to depict the variability of the soil properties over the area. The model was finally used as input for linear-equivalent ground response analysis. For the calculation of the amplification factors, special emphasis was given to the treatment and propagation of the uncertainties of the model parameters, whose different realizations have been accounted through a logic tree approach. |
| Late-glacial fluctuations of two southern Patagonia outlet glaciers revealed by high-resolution seismic surveys |
| Lodolo, E; Lozano, J; Donda, F; Bran, D; Baradello, L; Tassone, A; Romeo, R; Paterlini, M; Grossi, M; Caffau, M; Vilas, JF |
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Lago Argentino hosts various calving glaciers, among them the famous Perito Moreno. Whereas the onland late Pleistocene-Holocene glacial history is rather well constrained, the submerged glacier-related features were until now undisclosed. Here we present a series of high-resolution seismic profiles revealing moraine bodies associated with the late-glacial glacier dynamics and the first bathymetric map of the Brazo Rico and Brazo Sur, the two southern arms of Lago Argentino. At the eastern termination of Brazo Rico, we identified at the lake floor the submerged expression of the Puerto Bandera 3 moraine mapped onshore, which represents the oldest event (12,660 +/- 70 cal yr BP oldest minimum age) recognized in this lake arm, and seven other younger events expressed by a series of terminal and recessional moraines. Along the Brazo Sur, few moraine bodies have been imaged by seismic data. Here, the youngest temporal constraint comes from the Frias moraine (ca. 6000 cal yr BP), which closes off the southern end of the Brazo Sur. At the confluence of the two arms, the Perito Moreno and the former Frias glacier merged and flowed toward east during their late-glacial maximum advance (i.e., Puerto Bandera 1 moraine). The subaqueous evidence of moraine bodies testifies to the occurrence of previously undocumented pulses of the Perito Moreno and former Frias glaciers within the general phase of late Pleistocene-Holocene regression. |
| Post-Last Glacial Maximum evolution of a "fjord-type" lake based on high-resolution seismic data: the Lago Roca/Acigami (southern Tierra del Fuego, Argentina/Chile) |
| Bran, DM; Lozano, JG; Civile, D; Lodolo, E; Cerredo, ME; Tassone, A; Baradello, L; Grossi, M; Vilas, J |
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Lago Roca/Acigami is a "fjord-type" lake located in the southernmost part of South America, in the proximity of the Beagle Channel. A high-resolution seismic survey was carried out to analyse the seismic stratigraphy of the lake and to shed some light on the post-Last Glacial Maximum history of the area. Six seismic units were recognised, and their nature and depositional context were interpreted using seismic stratigraphy and acoustic facies analysis. A buried large ridge was identified within the glacial unit (SU1), interpreted as a frontal moraine that indicates a stabilisation phase. After retreat of the glacier from the basin, the trough was flooded by meltwater and a lake developed (SU2). The seismic facies, from bottom to top, depict a transition from ice-contact (SU2; SU3) to ice-distal proglacial conditions (SU4). A thick draping unit (SU5) marks a marine transgressive event and the instauration of a fjord environment in the basin. The marine transgression was a rapid event preceded by a fall in the lake level that caused an erosional unconformity. During the fjord phase the sedimentation remained controlled by meltwater discharge. Sea level fall, and subsequent disconnection from the Beagle Channel was accompanied by a progradation of the glaciofluvial deltaic sediments and the occurrence of several mass-wasting deposits
(SU6). |
| Combining shallow and deep geophysical information: the Yehuin-Chepelmut Fault Zone in the Magallanes fold and thrust belt (Tierra del Fuego, Argentina) |
| Lozano, JG; Tassone, A; Bran, DM; Onnis, L; Lodolo, E; Menichetti, M; Cerredo, ME; Esteban, F; Ormazabal, JP; Isola, J; Baradello, L; Vilas, JF |
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The outer Fuegian fold and thrust belt is the deformed sector of the Austral-Magallanes Basin, which underwent a contractional phase since the Late Cretaceous and a strike-slip phase during the Neogene. The area hosts two Neogene basins (Yehuin and Chepelmut) which have been mainly developed by the influence of wrench deformation, and were subsequently modified by glacial activity of the Ewan and Fuego glacier lobes of the Fagnano palaeoglacier. Geophysical surveys using Electrical Resistivity Tomography, onland shallow seismic surveys, and magnetometry, have been combined with outcrop analysis and deep seismic lines to recognize both shallow and intermediate deep structures related to the lacustrine basins. Four sets of faults with different deformation history were involved in the basin genesis. Comparison with the Deseado Fault Zone indicates similarities of the structural features between the two zones. The stress field interpreted as responsible for the origin of the studied basins is analogous to the one in the Deseado valley, located in the western Tierra del Fuego. Therefore, a transcurrent fault zone, here named Yehuin-Chepelmut Fault Zone, is proposed as part of the diffuse boundary between South America and Scotia plates. |
| Seismic imaging of the shallow and deep structures in the Ancona landslide area |
| Accaino, F; Baradello, L; Nicolich, R; Affattato, A |
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Following the large 1982 Ancona landslide, which affected a densely populated district with many man-made infrastructures, a big effort was made by the scientific community to study the area and a great amount of geophysical and geotechnical data were acquired. The region is part of the external domain of Central Apennine resulted by Neogene compressive deformations. The tectonic processes have resulted in instabilities along the entire central Adriatic coasts of Italy, marked today by large-scale gravitational phenomena. An early Pleistocene regional uplift formed a slope subject to glacioeustatic sea-level oscillations, with erosion and water infiltration, favouring instability and movements under the action of gravitational driving forces. Sliding surface formation and roto-translational displacements have occurred until the recent reactivations of earth-flows and chaotic mounds at the slope break in correspondence with the formation of the Peri-Adriatic basin. In this paper, we present images of seismic sections obtained from the processing of two sea-land reflection profiles and offshore very high-resolution prospecting. Our paper intends to reinforce the importance of a multi-disciplinary approach integrating geophysical data to geological, morphological and engineering methods. The seismic survey of the two sea-land sections considered a joint land-sea acquisition to image the subsurface in the transitional zone. Composite sections were obtained from the processing of differently recorded sub-datasets, which depended on the type of land and marine sources and sensors in combination with the unique frequency content, source strength and noise, such as the propagation of surface-waves or air-gun bubbles. The properly acquired and processed data yielded post-stack migrated depth converted seismic sections, reflecting interfaces down to approximately 1400 m depth, where the top of Messinian evaporites has been encountered. The final sections reveal the deep structural settings and the importance of the still active anti-Apennine transfer faults. The offshore Boomer high-resolution profiles show only the near sea-bottom sequences. These fluvio-deltaic Plio-Quaternary deposits represent the final filling phase of the foreland basins, exposed to sub-aerial erosion during the last glacial period and to submersion during the subsequent sea-level rise of approximately 120 m.The final sections reveal the deep structural settings and the importance of the still active anti-Apennine transfer faults. |
| Near-shore geophysical and geotechnical investigations in support of the Trieste Marine Terminal extensionet al |
| Masoli, CA; Petronio, L; Gordini, E; Deponte, M; Boehm, G; Cotterle, D; Romeo, R; Barbagallo, A; Belletti, R; Maffione, S; Meneghini, F; Baradello, L |
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The Port of Trieste is an international hub for land and sea trade with the dynamic markets of central and eastern Europe. Thanks to its deep natural draft (about 18 m), the modern high-capacity vessels can moor to the piers. In view of the foreseen increase in maritime traffic, this harbour is undergoing modernization in order to improve the commercial traffic capability. In this expansion plan, the container Trieste Marine Terminal, Pier VII, is seeking an extension by about 200 m. In support of this feasibility study, multidisciplinary data acquisition was conducted in order to characterize the seabed, the sub-bottom sediments and the bedrock (flysch formation) in front of the Trieste Marine Terminal. The acquisition of high-resolution swath bathymetry, side-scan sonar and magnetometer data allowed a detailed analysis of the seabed conditions from an environmental and safety perspective. High-resolution seismic reflection data enabled us to characterize the Plio-Quaternary soft sediments and the underlying bedrock. A static underwater refraction survey was performed using hydrophone array deployed on the sea bottom to obtain seismic velocities and to achieve a reliable time-to-depth conversion of reflection seismic data by first-arrival tomographic inversion. In addition to geophysical investigations, 11 offshore boreholes were drilled for detailed logging. In situ standard penetration tests were performed on core samples with the use of a pocket penetrometer and pocket vane in order to obtain uniaxial compressive strength, undrained shear strength and undrained cohesion values, and assess the cohesive soils. During drilling, 17 undisturbed samples and 12 semi-disturbed samples were extracted to perform laboratory tests for the identification of the principal geotechnical parameters. The goal was to obtain a reliable geological/geotechnical model in front of the Trieste Marine Terminal - from the seabed to the bedrock. Below the seafloor, a sequence of about 20-30 m thickness, containing Plio-Quaternary soft sediments, overlies the flysch, which locally presents alteration with rocks of reduced quality. The geophysical-geotechnical integrated approach allowed us to identify and map the top of the bedrock and provided valuable information for planning the pier extension project. |
| Shallow geophysics of the Asinara Island Marine Reserve Area (NW Sardinia, Italy) |
| Romeo, R; Baradello, L; Blanos, R; Congiatu, PP; Cotterle, D; Ciriaco, S; Donda, F; Deponte, M; Gazale, V; Gordini, E; Lodolo, E; Paganini, P; Pavan, A; Pietrapertosa, C; Sterzai, P; Vargiu, G; Zanello, A; Ramella, R; Yabar, DGN |
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We present a high-resolution swath bathymetric and backscatter map of the entire sector of the Marine Reserve Area (MRA) of the Asinara Island, along with a geological and sediment thickness map derived from the interpretation of a large set of high-resolution seismic profiles, and an airborne-derived hyperspectral image of the Asinara Island. Acquired data show that most of the eastern marine sector of the Asinara Island is characterized by quite gentle bathymetric gradients, whereas the western coastline appears to be very indented, with an articulated and rough morphology of the seafloor, which deepens sharply towards the open sea. The maps presented in this study at the 1:50.000 scale do not only provide the first, high-resolution bathymetry of the MRA of the Asinara Island but also may furnish the base for the creation of a benthic habitat map and a more comprehensive maritime spatial planning of this protected area. |
| Geophysical investigation of the Isonzo Plain (NE Italy): imaging of the Dinaric-Alpine chain convergence zone |
| Accaino, F; Busetti, M; Bohm, G; Baradello, L; Affatato, A; Dal Cin, M; Nieto, D |
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We present the results of a geophysical study carried out in the Isonzo Plain (NE of Italy), where the Paleogene External Dinarides and the Neogene eastern Southern Alps merge. We aim to provide imaging on the geological and tectonic setting in the area of convergence of the two chains. To this purpose multichannel seismic and geo-electrical profiles were acquired. Seismic processing and tomographic inversion of the first arrivals of multichannel seismic data were performed, allowing us to define geometries and velocities of the buried structures. Our data indicate the occurrence of a deformed Dinaric foredeep due to the Paleogene south-west migration of the External Dinaric chain and to the Neogene tectonic activity of the S-verging eastern South-Alpine chain. In addition, Plio-Quaternary transpressional fault systems produced structural highs such as the rocky outcrop of the Farra Hills rising from the plain. Plio-Quaternary tectonic activity displaced the late Miocene - Pliocene erosive surface at the top of the terrigenous sediment that fills the foredeep. The imaging of the buried structures provide a possible correlation with those outcropping in the Collio Hills and Karst Plateau. |
| Glacial-related morphology and sedimentary setting of a high-latitude lacustrine basin: The Lago Chepelmut (Tierra del Fuego, Argentina) |
| Lozano, JG; Tassone, A; Bran, DM; Lodolo, E; Menichetti, M; Cerredo, ME; Esteban, F; Ormazabal, JP; Isola, J; Baradello, L; Vilas, JF |
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Lago Chepelmut is a relatively small lake in size, of ellipsoidal shape, located in the outer fold-and-thrust belt of the Fuegian Andes (southernmost South America). High-resolution single-channel seismic profiles, integrated with geological information in the surrounding area, have allowed to reconstruct for the first time a bathymetric map of the lake and the architecture, distribution and thickness of the sedimentary cover. Two main seismic units were identified in the seismic records: (i) a Lower Unit of glacial nature, likely associated to the Last Glacial Maximum (LGM), and irregularly distributed through the basin, and (ii) an Upper Unit of lacustrine origin which drapes the entire basin. Submerged moraine deposits within the lake were also found from seismic data, and correlated with moraine arcs widespread distributed in the surroundings of the basin, These morphologies represent the recessional deposits left by the Ewan glacier lobe, one of the easternmost fronts of the Tierra del Fuego glaciers during the LGM. The lacustrine sedimentary record shows that the lake level was not constant through the recent history of the lake. Moreover, data analysis has shown that there is also an important structural component that has conditioned the evolution of the basin, in addition to that linked to glacial activity. |
| Origin and evolution of lago Yehuin (Tierra del Fuego, Argentina): Results from a geophysical survey |
| Lozano, JG; Tassone, A; Lodolo, E; Menichetti, M; Cerredo, ME; Bran, DM; Esteban, F; Ormazabal, JP; Baradello, L; Vilas, JF |
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Lago Yehuin, a WNW-ESE elongated basin located in the outer fold-and-thrust belt of the Fuegian Andes, occupies a compartmented structural depression originated along a segment of the left-lateral Lago Deseado fault system. This paper describes the first geophysical survey performed within the lake. New acquired high-resolution single-channel seismic data, integrated with geological infonnation in the surroundings of the Lago Yehuin, allowed to: (i) produce a complete bathymetric map of the lake, (ii) reconstruct the basement surface of the lake, and (iii) analyze the geometry, distribution, and thickness of the sedimentary infill. Two sub-basins were recognized within Lago Yehuin: A western sub-basin, 7.5 km long, with a maximum depth of 118 m; an eastern sub-basin, 7.2 km long with a maximum depth of 80 m. Both sub-basins are limited by a set of normal faults which overprint NE-verging thrusts. Three seismostratigraphic units have been identified in the seismic records: (1) a lower unit with wedged geometry interpreted as a mass flow deposits; (2) a thick (up to 120 m) intermediate unit of glacio-lacustrine nature and irregularly distributed in the Yehuin basin; (3) a thin (generally <10 m) upper lacustrine unit which drapes the entire basin. I,ago Yehuin is considered a Neogene basin generated by strike-slip tectonics that was later affected by glacial and glacio-lacustrine deposition. Interpreted submerged ridge moraines within Lago Yehuin are correlated with onland moraine arcs built by the complete recessional paths of Fuego and Ewan ice lobes. A significant structural control is proposed not only for the formation of Lago Yehuin, but also for the general paths of the northern arms of the Fagnano palaeo-glacier. |
| Thickness of marine Holocene sediment in the Gulf of Trieste (northern Adriatic Sea) |
| Trobec, A; Busetti, M; Zgur, F; Baradello, L; Babich, A; Cova, A; Gordini, E; Romeo, R; Tomini, I; Poglajen, S; Diviacco, P; Vrabec, M |
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We use various geophysical datasets (multibeam and singlebeam echosounder data, sub-bottom profiling Chirp and sonar data and very high-resolution boomer seismic data) along with published sedimentological data and depth data from nautical charts in order to create models of the depth of the seafloor and the base of Holocene marine sediment in the Gulf of Trieste. The two models are later used in order to calculate the thickness of marine Holocene sediment which has been depositing on the Late Pleistocene alluvial plain since the Holocene transgression in the Italian and Slovenian parts of the gulf. Thicker Holocene marine sedimentary sequences averaging at around 5 m are characteristic for the southeastern part of the gulf. In other parts of the gulf the Holocene marine sedimentary cover is very thin or even absent, except in close proximity to the shoreline and fluvial sediment sources, in the area of the Trezza Grande paleodelta and above topographic depressions of the Late Pleistocene base. The presented datasets available from the OGS SNAP data repository (http://doi.org/cpz2) represent a valuable reference for a wide variety of research disciplines dealing with the dynamic Earth system in the Gulf of Trieste and could be used as a valuable tool for designing sampling and geophysical campaigns in the studied area. |
| Hydrogeological effects of dredging navigable canals through lagoon shallows. A case study in Venice |
| Teatini, P; Isotton, G; Nardean, S; Ferronato, M; Mazzia, A; Da Lio, C; Zaggia, L; Bellafiore, D; Zecchin, M; Baradello, L; Celione, F; Corami, F; Gambaro, A; Libralato, G; Morabito, E; Ghirardini, AV; Broglia, R; Zaghi, S; Tosi, L |
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For the first time a comprehensive investigation has been carried out to quantify the possible effects of dredging a navigable canal on the hydrogeological system under-lying a coastal lagoon. The study is focused on the Venice Lagoon, Italy, where the port authority is planning to open a new 10 m deep and 3 km long canal to connect the city passenger terminal to the central lagoon inlet, thus avoiding the passage of large cruise ships through the historic center of Venice. A modeling study has been developed to evaluate the short (minutes), medium (months), and long (decades) term processes of water and pollutant exchange between the shallow aquifer system and the lagoon, possibly enhanced by the canal excavation, and ship wakes. An in-depth characterization of the lagoon subsurface along the channel has supported the numerical modeling. Piezometer and sea level records, geophysical acquisitions, laboratory analyses of groundwater and sediment samples (chemical analyses and ecotoxicity testing), and the outcome of 3-D hydrodynamic and computational fluid dynamic (CFD) models have been used to set up and calibrate the subsurface multi-model approach. The numerical outcomes allow us to quantify the groundwater volume and estimate the mass of anthropogenic contaminants (As, Cd, Cu, Cr, Hg, Pb, Se) likely leaked from the nearby industrial area over the past decades, and released into the lagoon from the canal bed by the action of depression waves generated by ships. Moreover, the model outcomes help to understand the effect of the hydrogeological layering on the propagation of the tidal fluctuation and salt concentration into the shallow brackish aquifers underlying the lagoon bottom. |
| Paleochannel and beach-bar palimpsest topography as initial substrate for coralligenous buildups offshore Venice, Italy |
| Tosi, L; Zecchin, M; Franchi, F; Bergamasco, A; Da Lio, C; Baradello, L; Mazzoli, C; Montagna, P; Taviani, M; Tagliapietra, D; Carol, E; Franceschini, G; Giovanardi, O; Donnici, S |
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We provide a model for the genesis of Holocene coralligenous buildups occurring in the northwestern Adriatic Sea offshore Venice at 17-24 m depth. High-resolution geophysical surveys and underwater SCUBA diving reconnaissance revealed meandering shaped morphologies underneath bio-concretionned rocky buildups. These morphologies are inferred to have been inherited from Pleistocene fluvial systems reactivated as tidal channels during the post-Last Glacial Maximum transgression, when the study area was a lagoon protected by a sandy barrier. The lithification of the sandy fossil channel-levee systems is estimated to have occurred at ca. 7 cal. ka BP, likely due to the interaction between marine and less saline fluids related to onshore freshwater discharge at sea through a sealed water-table. The carbonate-cemented sandy layers served as nucleus for subsequent coralligenous buildups growth. |
| GPR and high resolution seismic integrated methods to understand the liquefaction phenomena in the Mirabello Village (earthquake ML 5.9, 2012) |
| Baradello, L; Accaino, F |
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We performed a geophysical survey in Mirabello, a village of Emilia Romagna
Region of Northern Italy, to study the soil affected by the ML 5.9 earthquake of
2012, specifically the formation of surface ruptures by sand ejection due to the
liquefaction of shallow subsurface layers. The investigation was carried out
using ground penetrating radar and seismic reflection/refraction techniques.
This work confirms the importance of electromagnetic waves to map the shallow
subsurface extent of fractures and liquefied sand bodies, while the
high-resolution seismic reflection profile allowed us to map the fractures at
depth. The result obtained by tomographic inversion of first arrivals of seismic
data has been compared with a ground penetrating radar section acquired in the
same place, furnishing complementary information for the interpretation of the
section. |
| Anatomy of a submerged archipelago in the Sicilian Channel (central Mediterranean Sea) |
| Civile, D; Lodolo, E; Caffau, M; Baradello, L; Ben-Avraham, Z |
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The Sicilian Channel is a broad and shallow shelf which is geologically part of the African Plate. Its NW sector (the Adventure Plateau), where water depths rarely exceed 100 m, is punctuated by several kilometre-sized morphological highs. These elevations, formed by both sedimentary and volcanic rocks, emerged around middle Holocene time or earlier when they constituted a large archipelago. High-resolution single-channel and multichannel seismic reflection profiles, along with stratigraphic and lithological information derived from exploration wells and rock samplings, are analysed to derive the shallow and deep structural setting of these banks and identify their geological nature. The sedimentary banks (Talbot, Ante-Talbot, Panope, Nereo and Pantelleria Vecchia), presently located at water depths 8-40 m, are composed of Miocene rocks severely deformed by a late Miocene compressional phase which produced the external sector of the Sicilian-Maghrebian thrust belt. Tortonian-aged rock samples from the Pantelleria Vecchia Bank represent patch reefs that have mostly formed on structural highs. Sedimentary analogies suggest that other sedimentary banks of the Adventure Plateau may have the same origin. Galatea, Anfitrite and Tetide represent submarine volcanic edifices emplaced on major extensional faults formed during early Pliocene - Quaternary continental rifting of the Sicilian Channel. The present-day morphology of the banks is the result of repeated phases of subaerial exposure and drowning, especially since the Last Glacial Maximum. |
| Artificial recharge of the phreatic aquifer in the upper Friuli plain, Italy, by a large infiltration basin |
| Teatini, P; Comerlati, A; Carvalho, T; Gutz, AZ; Affatato, A; Baradello, L; Accaino, F; Nieto, D; Martelli, G; Granati, G; Paiero, G |
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To cope with the general reduction of water availability and increase the subsurface storage of high-quality surficial waters, an artificial recharge project is ongoing in northern Italy within the WARBO LIFE+ Project funded by EU. WARBO is aimed at implementing large-scale use of artificial recharge in Italy where water directives still strongly limit its application. In this context, the Mereto recharge site was selected in the upper Fruili plain where the water availability is guaranteed during winter period by the Tagliamento and Ledra Rivers. An infiltration basin, about 5.5 m deep and 45 x 7 m(2) wide, was built at Mereto in the early 2000s but the possibility of implementing the recharge has been allowed only very recently. The site is characterized by an elevation of 105 m asl and the depth to the groundwater table averages 50 m. Below a few meter-thick organic soil, the aquifer is composed by coarse deposits with an estimated thickness of 100 m and an average vertical hydraulic conductivity on the order of 10(-4) m/s. A 0.1 m(3)/s infiltration flow has been preliminary estimated (corresponding to an infiltration rate of 60 cm/h). Geophysical investigations (electrical resistivity tomography, high-resolution seismic surveys) together with infiltration and pumping tests have been carried out to characterize the vadose zone and the unconfined aquifer in the study area. Functional approaches and three-dimensional (3D) Finite Element numerical computations have been used to predict the effect of the artificial recharge. The results of these investigations will greatly reduce the hydrogeological knowledge gaps and will be used to fine tune the recharge program and to define the monitoring concept. This contribution aims to provide a methodology for the implementation of managed aquifer recharge programs using existing structures. |
| The lost Adventure Archipelago (Sicilian Channel, Mediterranean Sea): Morpho-bathymetry and Late Quaternary palaeogeographic evolution |
| Civile, D; Lodolo, E; Zecchin, M; Ben-Avraham, Z; Baradello, L; Accettella, D; Cova, A; Caffau, M |
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The rise in sea level following the Last Glacial Maximum (LGM) radically altered pre-existing geography, pushing back the former shorelines. The effect of this eustatic change was particularly intense and dramatic in flat lands and shelves, such as the Sicilian Channel. High-resolution bathymetric maps and Chirp seismic profiles analyzed in this study show that the Sicilian Channel, now lying at depths rarely exceeding 150 m, has emerged several times during its geological history. The last emergence was during the Early Holocene, when kilometre-sized islands punctuated the north-western sector of the Sicilian Channel, the Adventure Plateau, forming a broad archipelago. Many of these islands, now located in water ranging in depth from -10 to -40 m, are composed of highly deformed Neogene sedimentary rocks (Talbot, Ante-Talbot, Nereo, and Pantelleria Vecchia banks), while others represent submarine Pleistocene volcanic edifices (Galatea, Anfitrite and Tetide banks). Sedimentary cover in all of these banks is virtually absent. High-resolution seismic profiles allowed the identification of post-LGM morphological markers associated with the marine transgression, some of which are characterized by melt water-pulses, as demonstrated by the presence of specific and distinct erosional features. Combining swath bathymetric data with the seismic profiles, we have generated two palaeogeographic maps of the former Adventure Archipelago at two specific time frames: (1) at the end of the Younger Dryas stadial (11,500 yr B.P., corresponding to a former sea level of -60 m), and (2) at the end of the melt-water pulse 1B (11,200 yr B.P., corresponding to a former sea level of -42 m). Maps clearly show that in just 300 years the geography of the archipelago has changed dramatically, so much so that some islands have disappeared and some have decreased by more than 80% of their pre-Younger Dryas size. |
| An improved processing sequence for uncorrelated Chirp sonar data |
| Baradello, L |
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Chirp sonar systems can be used to obtain high resolution seismic reflection images of the sub-seafloor during marine surveys. The exact knowledge of the Chirp signature allows the use of deterministic algorithms to process the data, similarly to that applied to Vibroseis data on land. Here, it is described an innovative processing sequence to be applied to uncorrelated Chirp data, which can improve vertical and lateral resolution compared to conventional methods. It includes application of a Wiener filter to transform a frequency-modulated sweep into a minimum-phase pulse sequence. In this way, the data become causal and can undergo predictive deconvolution to reduce ringing and enhance vertical resolution. Afterwards, FX-deconvolution and Stolt migration can be applied to obtain an improved imaging of the subsurface. The result of this procedure is a seismic reflection image with higher resolution than traditional ones, which are normally represented using the envelope function of the signal. This technique can be particularly useful for engineering-geotechnical surveys and archaeological investigations that require a fine detail imaging of the uppermost meters of the sub-seafloor. |