My geophysical papers with ....

(if you ask a copy ...:)

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. [Engineering Geology (2016); doi:10.1016/j.enggeo.2016.06.027]

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. [Geological Magazine, (2016); doi:10.1017/S0016756815000485]

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 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 meltwater 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. [Global and Planetary Change, (2015); doi:10.1016/j.gloplacha.2014.12.003]

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. [Marine Geophysical Research, (2014); doi:10.1007/s11001-014-9220-1]

The Holocene succession located in the central part of the Venice Lagoon has been investigated by means of high-resolution seismic and core data, which document a full back-barrier depositional environment developed during the last 6 kyr. The studied succession, 4.5–23 m thick, consists of three seismic units bounded at the base by stratal surfaces marked by deep tidal channel incisions, recording main changes in the lagoon hydrodynamics as well as reorganizations of the tidal channel network. The recognized depositional and erosional phases in the lagoon deposits can be linked to both large-scale factors related to the Holocene sea-level rise and local factors in part due to the human impact. In particular, the lower unit is interpreted as the transgressive systems tracts of the Holocene sequence, initially characterized by the accumulation within small estuarine channels incised during the previous phase of subaerial exposure, whereas the upper units are interpreted as the highstand systems tracts, typified by the persistence of the lagoonal environment. The higher stratal surface records a hydrodynamic change related to a local transgression affecting a deltaic area placed just to the south, probably at least in part aided by human interventions. The Holocene succession accumulated in the central part of the Venice Lagoon testifies that the development of stratal surfaces in back-barrier settings, persisting during both transgressive and highstand conditions, may exhibit differences with respect to that predicted by current sequence stratigraphic models, and therefore, it is useful to improve the knowledge of these systems. [The Holocene, (2014); doi:10.1177/0959683614526903]

Lago Fagnano, an E-W elongated basin located in the central part of Isla Grande de Tierra del Fuego, occupies a structural depression originated along a segment of the Magallanes-Fagnano fault system. Its evolution was mostly conditioned by tectonic processes, and later was affected by glacial and glacio-lacustrine depositional events. New high-resolution single-channel seismic data, integrated with previous seismic profiles, and geological information acquired in the surroundings of the Lago Fagnano, allows us reconstructing the basement surface of the lake, and the geometry, distribution, and thickness of the glacial and glacio-lacustrine sequences. We recognized three main sub-basins within the Lago Fagnano: 1. a medium-size (ca. 21×5 km), deep (373 m), and asymmetric basin to the east; 2. an E-W trending (44×3 km), shallower (150 m) central sub-basin; and 3. a smaller (3.5×1.3 km), shallow (128 m) sub-basin to the west. The isopach sediment map shows that the most pronounced deposition occurred along the E-W axis of the lake, with a gradual increase in thickness towards east (from 100 to 150 m). The glacial deposits are widespread along the basin. The lacustrine sediments are preferentially localized along the E-W axis of the lake filling topographic lows. The shape of the sub-basins and their location in relation with the Magallanes-Fagnano fault system, along with the distribution, geometry, and thickness of the sedimentary units, show that the general morphology of the Lago Fagnano was mostly controlled by pre-existing and syntectonic features. Based on the structural data observed in the outcrops around the Lago Fagnano and the geophysical data, we proposed that the lake is composed by 4 amalgamated pull-apart sub-basins. [Andean Geology, (2014); doi:10.5027/andgeoV41n2-a02]

Within the central Mediterranean, the northwestern sector of the Sicily Channel is the unique area where two independent tectonic processes can be analyzed: the building of the Sicilian–Maghrebian Chain occurred in Late Miocene and the continental lithospheric rifting of the northern African margin occurred since Early Pliocene. These two geodynamic processes generated a peculiar structural style that is largely recognizable in the Adventure Plateau. This plateau is the shallowest part of the Sicily Channel, where water depths do not generally exceed 150 m. It hosts several areas of geomorphic relief, which in some cases rise up to less than 20 m beneath sea-level. A series of submarine magmatic manifestations occur in this area, mainly associated with the extensional phase which produced the rift-related depressions of Pantelleria, Malta and Linosa. Seismic-stratigraphic and structural analyses, based on a large set of multichannel seismic reflection profiles and well information acquired mostly for commercial purposes in the 1970s and 1980s, have allowed us to reconstruct the Triassic-Quaternary sedimentary succession of the Adventure Plateau and define its structural setting. A broad lithological distinction can be made between the successions ranging from Triassic to Paleogene, predominantly carbonate, and the successions ranging from Miocene to Quaternary, predominantly siliciclastic. Three main structural belts have been identified within the Adventure Plateau: (1) the northern belt, affected during Late Miocene time by ESE-verging thrusts belonging to the External Thrust System orogenic domain, which represents the lowermost structural level of the Sicilian–Maghrebian Orogen; (2) the Apenninic–Maghrebian domain of the Sicilian–Maghrebian Orogen, which occupies the northwestern sector of the Adventure Plateau, and that is overthrusted on the External Thrust System orogenic domain during the Late Miocene; (3) the extensional belt of the southwestern sector of the Adventure Plateau, affected by broad NW-trending, high-angle normal faults associated with the Early Pliocene continental rifting phase. The eastern boundary of the Adventure Plateau corresponds to a broadly N–S trending lithospheric transfer zone separating two sectors of the Sicily Channel characterized by a different tectonic evolution. [Marine Geophysical Research (2014); doi:10.1007/s11001-013-9205-5]

In this study the potential of combining high-resolution hydraulic tomographic and geophysical tomographic measurements to define site-specific relationships between geophysical and hydraulic parameters was investigated. We exploit the high-spatial resolution of hydraulic and geophysical tomographic images to define a representative and reliable site-specific relationship, if it exists, over an area, where geophysical and hydraulic tests are performed. The parameters involved in this study were: seismic P-wave velocity derived from seismic tomography; resistivity and electrical conductivity derived from electrical tomography (ERT); diffusivity, hydraulic conductivity and specific storage derived from hydraulic tomography. We derived a site-specific correlation function between the parameters P-wave velocity and diffusivity that shows the highest correlation of all hydraulic and geophysical parameter combinations. The transformation of the P-wave velocity field into a diffusivity field using the estimated site-specific correlation function allowed us to increase the significance of hydraulic tomographic as well as seismic tomographic measurements with respect to the spatial diffusivity distribution in the near subsurface. [Near Surface Geophysics (2013); doi:10.3997/1873-0604.2013034]

Vibroseis is a source used commonly for inland seismic exploration. This non-destructive source is often used in urban areas with strong environmental noise. The main goal of seismic data processing is to increase the signal/noise ratio where a determinant step is deconvolution. Vibroseis seismic data do not meet the basic minimum-phase assumption for the application of spiking and predictive deconvolution, therefore various techniques, such as phase shift, are applied to the data, to be able to successfully perform deconvolution of vibroseis data. This work analyzes the application of deconvolution techniques before and after cross-correlation on a real data set acquired for high resolution prospection of deep aquifers. In particular, we compare pre-correlation spiking and predictive deconvolution with Wiener filtering and with post-correlation time variant spectral whitening deconvolution. The main result is that at small offsets, post cross-correlation spectral whitening deconvolution and pre-correlation spiking deconvolution yield comparable results, while for large offsets the best result is obtained by applying a pre-cross-correlation predictive deconvolution. [Journal of Applied Geophysics (2013); doi:10.1016/j.jappgeo.2013.02.009]

Integrated seismic and well data provide for the first time a picture of the geological evolution of the Venice area over the last 5 Ma and a 3D subsoil model, which is fundamental to prediction of the anthropogenic uplift of Venice by seawater injection. A Pliocene southward prograding complex formed a shelf–slope system, whereas subsidence related to the Apennine foredeep development led to the establishment of a Early Pleistocene deep-water environment, favouring the accumulation of a thick turbidite succession. The NE progradation of the palaeo-Po river delta during the Middle Pleistocene promoted a drastic environmental revolution, followed by the deposition of cyclothems linked to glacio-eustatic changes. [Journal of Geological Society (2012); doi:10.1144/0016-76492011-093]

High-resolution seismic profiles acquired in the eastern sector of Lago Fagnano, the southernmost ice-free lake in the world, have shown the presence of very shallow gas-bearing layers in the upper sedimentary sequences. The gas-related features observed on seismic profiles include a typical, very strong reflection with reversed polarity, multiple reflections and acoustic blanking that hide subsurface sedimentary and structural features. The top of the acoustically high-amplitude layer is located between 0.3-1.7 m below the lake floor. It generally forms a sharp boundary, often marked by a varying offset probably due to different levels of gas penetration, which could be related to the lithology of the overlying sediments. To confirm the presence of gas, some gravity cores were recovered in places where the blanking effect was most relevant and in the supposed gas-free zone. Sediment core analyses have highlighted the occurrence of significant organic-rich components within the uppermost, largely unconsolidated sedimentary layers, in correspondence of the seismically-detected gassy zone, whereas only a few organic layers were found in the gas-free zone. We assume that the main origin of gas is linked to the presence of a shallow, thin peat-rich layer of Middle-Late Holocene age. In fact, the mapped gassy zone occurs in correspondence of the outlet of the Rio Turbio, the principal tributary of Lago Fagnano, which discharges waters coming from a relatively small sag pond located immediately to the east of the eastern shore of the lake. To date, this is the first evidence of shallow gas in Tierra del Fuego lakes. [Near Surface Geophysics (2012); doi:10.3997/1873-0604.2011040]

Microtremor measurements have been used for shallow engineering investigations for decades, but recently have been proposed as possible direct hydrocarbon indicators. In this paper, we have carried out field experiments to analyze some microtremors' features as average polarization and statistical stability. Our results seem to confirm the shallow nature of most microtremors' energy, although well data is still needed for a conclusive assessment. [Journal of Seismic Exploration 20 (4), (2011);]

Salt contamination in the coastlands surrounding Venice Lagoon (Italy) and Laizhou Bay (Shandong Province, China) is generally the result of the complex relationship between fresh, continental groundwaters, paleo-saltwaters in deep aquifers, marine waters, and the seawater encroachment upstream from the river mouths. Saltwater intrusion is also enhanced by the presence of ancient, sandy, buried paleo-channels that act as preferential pathways for groundwater flow and solute transport. The characterization of these hydro-geo-morphological features, considering both the architecture and the pore water quality, is an issue of paramount importance. In this work, after a short overview of the saltwater contamination occurrence that affects the coastlands of Venice Lagoon and Laizhou Bay, we report on the preliminary results of a Very High Resolution Seismic and Continuous Electrical Tomography test carried out in very shallow water (about 1 m) in the Venice Lagoon to test a technique suitable for the better understanding of the surficial-groundwater mixing process. The combined analysis of the two data sets highlights a correlation between lithostratigraphic discontinuities and heterogeneity in the fluid filling the subsurface. The promising results obtained in the Italian site support a prompt use of this integrated methodology on the Chinese study area too. [Bollettino di Geofisica Teorica ed Applicata (2011); doi:10.4430/bgta0024]

The occurrence of alternating dry/wet conditions in transitional environments, such as wetlands, deltas, and lagoons, usually challenges the use of traditional direct and geophysical surveys for comprehensive hydrogeologic investigations. Moreover, significant mixing between continental fresh groundwater and marine salty surface waters generally takes place in these flat coastal areas. Airborne electromagnetics (AEM) is a promising tool in this respect, as it provides, in a fast and cost effective manner, large-scale distribution of bulk electrical conductivities that can be used profitably to develop hydrogeologic models. The results of a SkyTEM AEM survey in the Venice Lagoon, Italy, show the capability of this technique to significantly improve the knowledge of the hydrogeologic setting of the lagoon and nearby coastland subsurface, irrespective of the different features characterizing the area. The environment consists of salt marshes, mud flats, shallows, tidal channels, islands, together with reclaimed farmlands crossed by natural watercourses and drainage channel networks. In particular, the AEM shows (i) the presence of fresh water (with resistivity larger than 20 Ω m) underneath the central part of the lagoon at depths from 10 to 25 m below m.s.l., (ii) the interface between different relevant stratigraphic units, e.g., the clayey layer bounding the Holocene–Pleistocene sedimentation, and (iii) the occurrence of areas with possible submarine fresh groundwater discharge. Moreover, the source and inland extent of the saltwater contamination in the shallow coastal aquifers along the southern margin of the lagoon are clearly revealed. AEM data were complemented with very high resolution seismic (VHRS) acquisitions. The integrated analysis of the two data sets allows distinguishing between lithostratigraphic heterogeneity and variability of the subsurface fluids. [Journal of Hydrology 411 (2011); doi:10.1016/j.jhydrol.2011.10.017]

Seismic investigation in the Gulf of Trieste allows the identification of the extension and activity of the External Dinarides tectonic structures. The Gulf of Trieste belongs to the Adriatic Apulian foreland, consisting of the tilted Paleocene-Mesozoic carbonate platform overlaid by the Eocene foredeep Flysch deposits and by recent Quaternary sediments. The data set consists of 250 km of multichannel seismic profiles, 16 km of high resolution data, collected offshore, and 5 km of multichannel seismic profiles collected onshore since 2003. The main tectonic features identified in the study area are: a) the Trieste fault zone, occurring on the Karst coastal front, up to 2-3 km offshore; it is a Dinaric thrust system with about 1400 m of total vertical displacement in the carbonates, possibly affected by neotectonic activity; b) Dinaric frontal thrusts, present in the Gulf of Trieste and in the southern Friuli Plain, deforming the Flysch sequence and producing low angle faults in the carbonates; c) occurrence of possible NE-SW faults dissecting the Dinaric thrusts. [Bollettino di Geofisica Teorica ed Applicata (2010);]

CO2 storage in the subsurface is becoming more and more attractive as a means to reduce CO2 emissions to the atmosphere and hence minimize human-induced global warming. The ability to monitor and verify these CO2 storage reservoirs is a key element for further implementation of other storage sites. Since the current sites fortunately do not appear to “leak” CO2, it is difficult to test the most suitable monitoring techniques for their ability to detect CO2 migration pathways. In this study different monitoring methods have been evaluated at a site in the Latera caldera (central Italy) where natural, thermo-metamorphically produced CO2 finds its way to the surface. The aim of the study is to identify which monitoring methods can detect the migrating CO2 and to gain understanding of the preferential migration pathways of the CO2. Different geophysical monitoring techniques have been deployed at a small, 200 x 500 m study area located in the centre of the caldera: 2D reflection seismics (testing different sources), 2D refraction seismics, multi-channel analysis of surface wave (MASW), ground penetrating radar (GPR), micro-gravity,
magnetometer, self-potential (SP), 2D and 3D geo-electrical measurements and electro-magnetic (EM31 and EM34) measurements. Furthermore CO2 flux measurements were performed in a dense grid over the study area, and a limited number of soil gas samples collected along two profiles, to “ground-truth” the geophysical results. In general a good correlation has been observed between the different methods and the presence of CO2. Geophysical responses, especially those of the reflection seismic and magnetometer data, change markedly from one side of the proposed main fault to the other, probably linked to a sharp geological boundary. The observed fractures on the seismic data seem to correspond with the preferred migration pathways of the CO2. The GPR and resistivity measurements detect strong variations in conductivity induced by the presence of the CO2 up to about 2 and 20 meters depth, respectively, as supported by the soil gas and flux measurements. [Energy Procedia (2009); doi:10.1016/j.egypro.2009.01.295]

The southern portion of the Venice lagoon contains a relatively thick (up to 20m) Holocene sedimentary body tha tre presents a detailed record of the formation and evolution of the lagoon. New very high-resolution (VHR) seismic profiles provided a detailed investigation on depositional geometries, internal bounding surfaces and stratal relationships. These informations, combined with core analysis, allowed the identification of large-to medium-scale sedimentary structures (e.g. dunes, pointbars), the corresponding sedimentary environment, and of retrogradation a land progradational trends. In addition, the availability of dense seismic network produceda 3D reconstruction of the southern lagoon and the recognition of the along-strike and dip variability of the stratal architecture. Three main seismic units(H1–H3), separated by key stratal surfaces (S1-S3), form the Holocene succession in the southern Venice lagoon. This succession is bounded at the baseby the Pleistocene/ Holocene boundary (the surface S1), which consists of a surface of sub aerial exposure locally subjected to river incision. The lower part of the Holocene succession (up to 13m thick)consists of incised valley fills passing upward into lagoon and then shallow-marine sediments (Unit H1),and there fore shows a deepening-upward trend and a retrogradational stacking pattern. A prograding delta and adjacent shorelines, showing internal clinoforms downlapping on to the top of Unit H1 (the surface S2), form the middle part of the Holocene successio (Unit H2, up to 7.5m thick). Unit H2 is interpreted as a result of a regressive phase started about 6kyr BP and continued until recent time. The upper part of the Holocene succession (Unit H3) consists of lagoonal deposits, including tidal channel and tidal and subtidal flat sediments, that abruptly overlie Unit H2. Unit H3 is thought to represent a drowning of the area primarily due to human interventions that create drivers diversion and consequent delta abandonment during historicaltime. [Continental Shelf Research (2009); doi:10.1016/j.csr.2009.03.006]

Acquiring large amounts of data in very shallow waters of the immediate subtidal zone using a multichannel technique is unaffordable because moveout correction and a standard stacking procedure are required. The conventional inline longitudinal deployment of source and streamer leads to a phase difference along the hydrophone array for nonvertical arrivals. The array in this system is hard wired, so these phase differences cannot be accounted for and the summed output is attenuated as a result. We propose a transverse configuration, whereby the variation in phase along the array is smaller. The summed output improves because pairs of hydrophones with equivalent absolute offset are stacked in phase as a result of the symmetric configuration; however, all of the hydrophones are out of phase in the conventional geometry. Even at depths of 40m, a better image is obtained. The technique has been used during surveys in the Venice lagoon, where the water depth ranges from 40 cm to 2 m. [Geophysics (2008); doi:10.1190/​1.2976117]

The sequence-stratigraphic investigation by Very High-Resolution (VHR) seismic profiles allowed recognition of the detailed architecture of the late Pleistocene and Holocene succession of the Venice area. In this way deposits previously known by the analyses of scattered cores, mainly taken along the lagoon margin and the littoral strips, have been correlated at regional scale including the near offshore sector and the result has pointed out the lateral variability of the stratal architecture. Late Pleistocene deposits consist of an aggrading floodplain and fluvial channel fills accumulated during decreasing eustatic sea level, and they are coeval with offlapping forced regressive marine wedges in the Central Adriatic basin. The Holocene sequence is composed of three main seismic units separated by major stratal surfaces. Unit 1 (up to 9 m thick) is formed by channelized deposits separated by areas showing sub-horizontal and hummocky reflectors, and is bounded at the base by a surface that records prolonged conditions of subaerial exposure and at the top by a flatter surface resulting from erosion by marine processes. Deposits of Unit 1 are interpreted as estuarine and distributary channel fills, and back-barrier strata. Unit 2 is well distinguishable from Unit 1 only in the offshore area and at the barrier island bounding the Venice Lagoon, and is composed of a prograding marine wedge (up to 10 m thick) that interacts laterally with ebb tidal deltas. Unit 3 consists of a tidal channel complex and inlet deposits, which testify the evolution of the lagoon area. Tidal channels are entrenched in the lagoon mud flat (coeval with Units 1-2) and cut the Pleistocene-Holocene boundary in several places. Following current sequence-stratigraphic concepts, the Holocene sequence is composed of a paralic transgressive systems tract (TST) (Unit 1) overlying a sequence boundary (the Pleistocene-Holocene boundary) and overlain by a marine highstand systems tract (HST) (Unit 2) in seaward locations and by highstand lagoonal deposits landwards. TST and HST are separated by a downlap surface that is amalgamated with a wave ravinement surface in several places. Unit 3 is coeval with the upper part of Unit 2, and its development has been favoured by human interventions, which led to a transgression limited to the lagoon area. Local factors during the deposition, i.e. subsidence, sediment supply, physiography, and current/wave regimes, led to a significant lateral variability in the architecture of the Holocene sequence, as evidenced by the extreme thickness variation of the TST along both depositional strike and dip. The HST, instead, shows less pronounced strike variations in the stratal architecture. Also, present data clearly evidence that the human impact has a great relevance in influencing the late Holocene sedimentation. [Marine Geology (2008); doi:10.1016/j.margeo.2008.05.010]

The paper deals with a reflection seismic acquisition survey carried out on the Great Ancona Landslide, a huge landslide body on the Italian Adriatic coast involving part of the city of Ancona. To investigatethe area we carried out a joint land-marine seismic acquisition that gave us a continuous image of the subsurface in the land-sea transition zone where the landslide foot is supposed to be located. A specifically designed interface unit connected the analog ocean-bottom cable (OBC) lying along the sea-floor to the telemetry system used on land. The effectiveness of different source types for both marine and land shooting was tested in the field, by computing and analysing the frequency-time (FT) response ofthe recorded seismograms. The various sub-datasets obtained (land-land, land-marine, marine-land and marine-marine) were kept separate because of the different signal properties and the kinds of noise present; a short description of such noise is given. Finally, the acquisition statistics are discussed, and a preliminary image of the s)ubsurface in time has been achieved from the marine-marine data. [Near Surface Geophysics (2005); doi:10.3997/1873-0604.2005019]

We propose the exploding-reflector method to simulate a monostatic survey with a single simulation. The exploding reflector, used in seismic modeling, is adapted for ground-penetrating radar (GPR) modeling by using the analogy between acoustic and electromagnetic waves. The method can be used with ray tracing to obtain the location of the interfaces and estimate the properties of the medium on the basis of the traveltimes and reflection amplitudes. In particular, these can provide a better estimation of the conductivity and geometrical details. The modeling methodology is complemented with the use of the plane-wave method. The technique is illustrated with GPR data from an excavated tomb of the nineteenth century. [Geophysics (2004); doi:10.1190/1.1707066]

An international archaeological and geophysical expedition was carried out to study Iron Age tombs of the Saka culture in southeastern Kazakhstan. Single-fold and multifold ground-penetrating radar (GPR) surveys, in two and two and a half dimensions, focused on the identification of burial chambers beneath the mound-shaped Saka tumuli, named kourgans. Primary objectives of the geophysical study were the testing and optimization of GPR techniques for studying this type of tomb and the reconstruction of subsurface images of use for the design of archaeological excavations. Single-fold GPR grids with line spacing ranging between 50 and 200 cm were obtained at each of the 13 sites selected. After identification of the sectors of major potential interest from data processing performed directly in the field and interpretation of the single-fold grids, multifold profiles with average 1200 per cent fold were designed and performed. Processing of the data focused on velocity analyses, pre-stack coherent noise attenuation by means of FK and KL filters, stacking and analysis of the instantaneous attributes of the complex radar trace. Multifold GPR data processing techniques achieved a substantial increment in the signal to noise ratio at most sites, allowed accurate depth conversions of the stacked profiles (average deviation of estimated target location from the actual target was less than 5% of total depth) and provided indications to identify the characteristic response from the target of interest through the joint interpretation of pre-stack gathers, velocity analysis and amplitude versus offset analysis. Interpretation of stacked sections and three-dimensional models obtained from the single-fold/multifold grid allowed the identification of a burial chamber located at an estimated depth of 140–150 cm, which was excavated successfully by the archaeological team. Further reflectors with similar characteristics are shown from other sites, which will be excavated by the next archaeological expeditions to the area.[Archaeological Prospection (2001); doi:10.1002/arp.162]

A 2.5-D and 3-D multi-fold GPR survey was carried out in the Archaeological Park of Aquileia (northern Italy). The primary objective of the study was the identification of targets of potential archaeological interest in an area designated by local archaeological authorities. The second geophysical objective was to test 2-D and 3-D multi-fold methods and to study localised targets of unknown shape and dimensions in hostile soil conditions. Several portions of the acquisition grid were processed in common offset (CO), common shot (CSG) and common mid point (CMP) geometry. An 8×8 m area was studied with orthogonal CMPs thus achieving a 3-D subsurface coverage with azimuthal range limited to two normal components. Coherent noise components were identified in the pre-stack domain and removed by means of FK filtering of CMP records. Stack velocities were obtained from conventional velocity analysis and azimuthal velocity analysis of 3-D pre-stack gathers. Two major discontinuities were identified in the area of study. The deeper one most probably coincides with the paleosol at the base of the layer associated with activities of man in the area in the last 2500 years. This interpretation is in agreement with the results obtained from nearby cores and excavations. The shallow discontinuity is observed in a part of the investigated area and it shows local interruptions with a linear distribution on the grid. Such interruptions may correspond to buried targets of archaeological interest. The prominent enhancement of the subsurface images obtained by means of multi-fold techniques, compared with the relatively poor quality of the conventional single-fold georadar sections, indicates that multi-fold methods are well suited for the application to high resolution studies in archaeology. [Journal of Applied Geophysics (1999); doi:10.1016/S0926-9851(98)00047-0]

Non destructive techniques to detect and monitor the sub-surface behaviour of a salt-water solution within a sand-gravel aquifer 2003

An interdisciplinary geophysical approach to detect cavities in a karst region 2001

Multi-fold GPR and magnetic gradiometry for ultra high resolution study of archaeological sites 1999