Vincenzo Di Fiore

Seismic study of the ‘41st Parallel’ Fault System offshore the Campanian–Latial continental margin, Italy

Abstract A set of seismic reflection lines, collected in the Southern Tyrrhenian Sea offshore the Campanian–Latial continental margin has been selected and interpreted. The aim is to characterize: (1) the structural features of the 41st Parallel Line (41PL), an E–W elongated magnetic anomaly zone separating the Northern Tyrrhenian domain from the Southern Tyrrhenian domain; and (2) to study the relationships between the 41PL and the Ortona–Roccamonfina Line (ORL), a tectonic structure transversal to the Apennines along which the Northern Apennine Arc merges the Southern Arc. The interpretation of the seismic lines is discussed in light of the available geological (stratigraphic and structural) and geophysical (gravimetric and magnetic) information. Results show that the Campanian–Latial continental margin is characterized by a series of structural lows and highs that match with the main structures on the mainland (Mt. Massico horst, the Volturno and Garigliano depressions). The study area is characterized by ESE–WNW to E–W and NE–SW striking faults. The activity of these faults developed during Pliocene–Early Pleistocene times. ESE–WNW to E–W faults display structures consistent with strike–slip movements. These faults, which are located on the maximum gradient of the E–W elongated magnetic alignment of 41PL, are responsible for the SSE translation of the offshore sector of the Mt. Massico horst. The horizontal dislocation of Mt. Massico suggests left-lateral movements for the ESE–WNW to E–W faults. The NE–SW faults that affect the Mt. Massico horst, which represents the southern tip of ORL, show seismic features consistent with normal movements, as also revealed by inland data. Since: (1) background seismicity is virtually absent along the study area; and (2) the uppermost seismic reflectors seem unaffected by faults, it is very likely that both the ORL and 41PL fault zones are now inactive, at least in the Campanian–Latial area. Seismic data indicate that ORL is older than 41PL and support the interpretation that the 41PL represents a deep-seated transfer fault system formed in response to the different rates of opening of the Tyrrhenian Sea. The strike–slip movements along the 41PL faults and the normal movements along the ORL faults are consistent with a NW–SE extension, which is responsible for the longitudinal extension in the Southern Apennines belt.

Structural setting of the Bay of Naples (Italy) seismic reflection data: implications for Campanian volcanism

Abstract This paper focuses on the recent tectonic evolution of the Bay of Naples with the aim of exploring the connection between local tectonics and volcanism. We reprocessed the seismic reflection dataset acquired in the area in the late 1973. The new processing was highly successful in obtaining a decisive strong reduction of random noise, removal of coherent noise and reduction of spatial aliasing. Classical interpretative schemes and complex attributes of seismic traces were used to reconstruct fault kinematics and reflector patterns. The results show that the faults affecting the Bay of Naples exhibit prevailing NE structural strikes, with the exception of the Pozzuoli Caldera where NW patterns are also common. Many faults are subvertical and show seismic evidence of volcanic activity along them. A main alignment of conjugate NE–SW faults, named here as “Magnaghi–Sebeto line”, intersects several submarine volcanic banks and separates the bay into two sectors, characterized by important geological, geophysical and petrochemical differences. The structural configuration of the bay may reflect the occurrence of either oblique extension or a transfer zone of the NW–SE fault system, along which, in the Campanian–Lucanian Apennine chain, great vertical displacements occur.

Seismic Tomography Experiment at Italy's Stromboli Volcano

Stromboli Island, located in the southern Tyrrhenian Sea, is the emerged part (about 900 meters above sea level) of an approximately 3-kilometer-high stratovolcano. Its persistent Strombolian activity, documented for more than 2000 years, is sometimes interrupted by lava effusions or major explosions. Despite the number of recently published geophysical studies aimed at clarifying the volcanos eruption dynamics, the spatial extent and geometrical characteristics of its plumbing system remain poorly understood. In fact, knowledge of the inner structure and the zones of magma storage is limited to the upper few hundred meters of the volcanic edifice [Chouet et al., 2003; Mattia et al., 2004], and P and S wave velocity models are available only in restricted areas [Petrosino et al., 2002].

Characterization of shallow volcanoclastic deposits by turning ray seismic tomography: an application to the Naples urban area

Several bidimensional seismic tomography surveys were carried out in urban areas of the Campi Flegrei and Somma-Vesuvius volcanic districts, Naples, Italy, with the aim of investigating the shallow subsurface and of detecting small-scale variation and heterogeneities within pyroclastic deposits. The method employed in this study is turning ray tomography (TRT). With accurate field acquisition and travel time picking and correct choice of inversion parameters, it was possible to obtain detailed P-wave tomographic models in areas characterized by thick beds of pyroclastic deposits. We were able to identify zones with heterogeneous P-wave velocities caused by the presence of buried paleochannels, or by differential welding and zeolitization in the subsurface of the investigated areas. TRT appears to be a suitable method to investigate deposits for engineering applications, at sites where the bedrock is too deep to be reached by foundations and the overburden is characterized by much heterogeneity.

Application of X-Band Wave Radar for Coastal Dynamic Analysis: Case Test of Bagnara Calabra (South Tyrrhenian Sea, Italy)

Sea state knowledge has a key role in evaluation of coastal erosion, the assessment of vulnerability and potential in coastal zone utilization, and development of numerical models to predict its evolution. X-band radar measurements were conducted to observe the spatial and temporal variation of the sea-state parameters along a 3 km long sandy-gravelly pocket beaches forming a littoral cell on Bagnara Calabra. We produced a sequence of 1000 images of the sea state extending offshore up to 1 mile. The survey has allowed monitoring the coastline, the directional wave spectra, the sea surface current fields, and the significant wave heights and detecting strong rip currents which cause scours around the open inlets and affect the stability of the submerged reef-type breakwaters. The possibility to validate the data acquired with other datasets (e.g., LaMMA Consortium) demonstrates the potential of the X-band radar technology as a monitoring tool to advance the understanding of the linkages between sea conditions, nearshore sediment dynamics, and coastal change. This work proves the possibility to obtain relevant information (e.g., wave number, period, and direction) for evaluation of local erosion phenomena and of morphological changes in the nearshore and surf zone.

A new tool to promote sustainability of coastal zones. The case of Sele plain, southern Italy

To support the implementation of integrated coastal zone management (ICZM) plans, a quantitative methodology was assessed, fitting for both the National and Regional scale. According to the indicators proposed by the Deduce Consortium (Indicators guideline: to adopt and indicator-based approach to evaluate coastal sustainable development. Department of the Environment and Housing, Government of Catalonia, Barcelona, 2007), we propose a procedure to define monothematic and synthetic indexes useful in explaining the territory status. To achieve this goal, we used a methodology implemented in a geographic information systems (GIS) framework which had allowed us to draw these indexes into maps, making them valuable tools to inform the stakeholders about the weaknesses and strengths of the coastal areas, to involve them in the ICZM implementation process according to a bottom-up approach. We present here an application of this methodology to the inland sectors of the Sele coastal plain (Tyrrhenian coast, Southern Italy), which is affected by natural hazards and territorial fragmentation. Moreover, this plain is characterized also by large untouched areas to be preserved. We illustrate for the above area, the importance of GIS to manage and integrate large amounts of numerical data, produced by several projects, realized in the past decade in the framework of the environmental management. For this purpose, monothematic and synthetic index maps have been drawn to transfer the appropriate knowledge of the territory status to stakeholders.

High Resolution Seismic Reflection Methods to Detect Near Surface Tuff-Cavities: A Case Study in the Neapolitan Area, Italy

The Neapolitan region of Italy is plagued by the presence of shallow manmade cavities in lithoid tuffs that cause problems for communities because they produce building damages and loss of human lives. A high resolution P-wave seismic-reflection technique was successfully used to define a cavity 6 m by 10 m in horizontal dimensions and with a height of about 6 m located in a tuff layer 10 to 19 m below ground level. Such a cavity was located at Afragola (near Naples) where the local geology is typical of the Neapolitan area. The seismic dataset was acquired by using end-on spread geometry, with 0.25 m spacing for shots and 0.5 m for receivers. The application of band–pass filtering (30–150 Hz) allowed us to remove incoherent noise from the data, while an additional equivalent slope (Vs) of 0.005 s m cut in the FK transform results in ground-roll noise removal. Both the acquisition and processing methods have been necessary to investigate and define the shape and dimensions of the targeted cavity.

High resolution seismic data coupled to Multibeam bathymetry of Stromboli island collected in the frame of the Stromboli geophysical experiment: implications with the marine geophysics and volcanology of the Aeolian Arc volcanic complex (Sicily, Southern Tyrrhenian sea, Italy)

New high resolution seismic data (Subbottom Chirp) coupled to high resolution Multibeam bathymetry collected in the frame of the Stromboli geophysical experiment aimed at recording active seismic data and tomography of the Stromboli Island are here presented. The Stromboli geophysical experiment has been already carried out based on onshore and offshore data acquisition in order to investigate the deep structure and the location of the magma chambers of the Stromboli volcano. A new detailed swath bathymetry of Stromboli Island is here shown and discussed to reconstruct an up-to-date morpho-bathymetry and marine geology of the area compared to the volcanologic setting of the Aeolian Arc volcanic complex. Due to its high resolution the new Digital Terrain Model of the Stromboli Island gives interesting information about the submerged structure of the volcano, particularly about the volcano-tectonic and gravitational processes involving the submarine flanks of the edifice. Several seismic units have been identified based on the geologic interpretation of Subbottom Chirp profiles recorded around the volcanic edifice and interpreted as volcanic acoustic basement pertaining to the volcano and overlying slide chaotic bodies emplaced during its complex volcano-tectonic evolution. They are related to the eruptive activity of Stromboli, mainly poliphasic and to regional geological processes involving the intriguing geology of the Aeolian Arc, a volcanic area still in activity and needing improved research interest.

Integrated hierarchical geo-environmental survey strategy applied to the detection and investigation of an illegal landfill: A case study in the Campania Region (Southern Italy)

This paper describes an approach to detect and investigate the main characteristics of a solid waste landfill through the integration of geological, geographical and geophysical methods. In particular, a multi-temporal analysis of the landfill morphological evolution was carried out using aerial and satellite photos, since there were no geological and geophysical data referring to the study area. Subsequently, a surface geophysical prospection was performed through geoelectric and geomagnetic methods. In particular, the combination of electrical resistivity, induced polarization and magnetic measurements removed some of the uncertainties, generally associated with a separate utilization of these techniques. This approach was successfully tested to support the Prosecutor Office of Salerno (S Italy) during a specific investigation about an illegal landfill. All the collected field data supported the reconstruction of the site-specific history, while the real quarry geometry and site geology were defined. Key elements of novelty of this method are the combination and the integration of different methodological approaches, as the parallel and combined use of satellite, aerial and in-situ collected data, that were validated in a real investigation and that revealed the effectiveness of this strategy.

Shallow Seismic Refraction Tomography and MASW Survey for Investigating the Fractures Along Qena-Safaga Road, South of Egypt

Qena-Safaga road, which is one of the vital transportation lines in south of Egypt, is affected by a set of recent NE-SW to ENE-WSW vertical tensile and en echelon fractures. These fractures are distributed for about 12 km along both sides of the road and constitute a major threat to the infrastructure and environment. Some studies suggested the tectonic origin of these fractures while others suggested that they were formed due to geotechnical problems in the shallow subsurface soil. In order to study the nature and distribution of these fractures in the subsurface, low cost seismic surveys were conducted at the area of KM 22 of Qena-Safaga road. Eleven shallow seismic refraction lines as well as three MASW lines were acquired. The seismic refraction data were analyzed using tomographic methods to produce 2D velocity-depth models. To estimate the near surface seismic properties such as Vp/Vs and Poisson’s ratio that are important for the geologic interpretation of the data, MASW data where analyzed to obtain 1D shear wave velocity models. 3D images including 3D volume, fence diagram and depth slices were also produced to study the vertical and lateral variation of the P-wave velocity. In the resulted 2D tomographic models, three seismic units were deduced. The first unit represents the thin weathered surface layer having P-wave velocities of 300–700 m/s. The second unit has P-wave velocities of 700–1600 m/s and S-wave velocities of 281–926 m/s. It may represent the marl unit of Pliocene Durri Formation. Its thickness ranges from 11.8 m to 30 m. The bedrock was deduced to be at depths from 13 to 40 m and is characterized by velocities greater than 1600 m/s. The fractures were traced down to the bedrock along the seismic sections. The variable thickness of the marl unit as well as the variable depths of the bedrock were deduced to be resulting from the effect of subsurface.