Search results for "Seismology"
showing 10 items of 301 documents
The 15 March 2007 explosive crisis at Stromboli Volcano, Italy: assessing physical parameters through a multidisciplinary approach
2011
Basaltic volcanoes are dominated by lava emission and mild explosive activity. Nevertheless, many basaltic systems exhibit, from time to time, poorly documented and little-understood violent explosions. A short-lived, multiblast explosive crisis (paroxysmal explosion) occurred on 15 March 2007 during an effusive eruptive crisis at Stromboli (Italy). The explosive crisis, which started at 20:38:14 UT, had a total duration of ∼5 min. The combined use of multiparametric data collected by the permanent instrumental networks (seismic, acoustic, and thermal records) and a field survey carried out immediately after the event enabled us to constrain the eruptive dynamics and quantify physical param…
Electromagnetic and ultrasonic investigations on a Roman marble slab
2011
The archaeological museum of Rome asked our group about the physical consistency of a marble slab (second to third century AD) that recently fell during its travel as part of an exhibition. We decided to use different methodologies to investigate the slab: namely a pacometer (Protovale Elcometer) to individuate the internal coupling pins, and ground-penetrating radar (GPR) (2000 MHz) and ultrasonic (55 kHz) tomographic high-density surveys to investigate the internal extension of all the visible fractures and to search for the hidden ones. For the ultrasonic data, tests were carried out to optimize the inversion parameters, in particular the cell dimensions. Surely, the choice of cell size …
Complex vein systems as a data source in tectonics: An example from the Ugab Valley, NW Namibia
2014
Abstract Neoproterozoic metaturbidites in the Lower Ugab Domain, Namibia, contain a complex network of four sets of quartz-calcite veins, overprinted by km-scale folds associated with four regional foliations. The veins formed by fluid overpressure predating the main deformation. Deformation structures developed at the junction of two mobile belts during the assembly of Gondwana, the NS Kaoko Belt, and the EW trending Damara Belt. Km-scale NS trending folds were initiated during EW constriction in the Kaoko Belt, while their further development and all subsequent events are related to constriction in the EW-Damara Belt, with coeval sinistral strike slip in the Kaoko Belt. Deformation of the…
GPS Monitoring of the Scopello (Sicily, Italy) DGSD Phenomenon: Relationships Between Surficial and Deep-Seated Morphodynamics
2015
The Scopello area, which is located along the north-western Tyrrhenian coastal sector of the Sicilian chain (Italy), is widely affected by Deep-seated Gravitational Slope Deformation (DGSD) phenomena, which are mainly the result of a geomorphologic setting marked by the outcropping of an overthrust plan, limiting a brittle fractured carbonate slab, laid onto a ductile marly-clayey substratum. Due to the very advanced stage of the deformation phenomena, a coupled morphodynamic style has established between shallow landslides and DGSD phenomena, affecting the exhumed ductile substratum and the overlaying rigid dismantled slab, respectively. A GPS network was realized for monitoring the Scopel…
Tertiary maars of the Hocheifel Volcanic Field, Germany
2008
In the Hocheifel only three maars are known. The Eckfeld Maar, filled with Eocene lacustrine sediments, is located at the southern boundary of the volcanic field, where the Tertiary peneplain has been eroded only slightly. The ages of the Jungferweiher Maar in the southeast and the Dottingen Maar in the northeast of the Tertiary Hocheifel Volcanic Field (THVF) are unknown and their timing within the THVF is uncertain. In contrast to the surrounding area, the central part of the THVF is deeply eroded. Here, six large diatremes (>600 m) were identified in the area of Kelberg with one exception. So far, no relics of crater sediments have been found within the large diatremes. They probably rep…
Deep fluid transfer evidenced by surface deformation during the 2014–2015 unrest at Piton de la Fournaise volcano
2016
International audience; Identifying the onset of volcano unrest and providing an unequivocal identification of volcano reawakening remain challenging problems in volcanology. At Piton de la Fournaise, renewal of eruptive activity in 2014–2015, after 41 months of quiescence and deflation, was associated with long-term continuous edifice inflation measured by GNSS. Inflation started on June 9, 2014, and its rate progressively increased through 2015. Inflation onset was rapidly followed by an eruption on June 20–21, 2014, showing that volcano reactivation can be extremely fast, even after long non-eruptive phases. This short-lived eruption involved a shallow source (1.3–1.9 km depth below the …
Geochemical investigations applied to active fault detection in a volcanic area: the North-East Rift on Mt. Etna (Sicily, Italy)
1999
Geochemical investigations were performed on the Northeast Rift of Mt. Etna, a prominent volcanic structure of this volcano. Low-temperature fumaroles were found on the upper part of this area and the isotopic compositions of C(CO2) and He suggest a likely magmatic origin of the emitted gases. On the contrary, very low degassing was found in the lower part of the NE-Rift, with CO2 concentrations generally very close to those in air. This pattern is probably due to sealing of the eruptive fissures by the repeated injections of magma solidified into dikes and by consequent shallow hydrothermal alteration of the fissured rocks due to residual magma degassing. High soil CO2 concentrations were …
New insights from recently migrated CROP multichannel seismic data at the outermost Calabrian arc accretionary wedge (Ionian sea)
2011
This study addresses selected aspects of the stratigraphic-structural setting of the outermost Calabrian Arc accretionary wedge and underlines relationships between structural development and Messinian evaporite stratigraphy through the analysis of re-processed CROP multichannel seismic reflection profiles. A detailed seismostratigraphic analysis, calibrated with P-velocities compiled by previous works, images a general bipartition of the Messinian evaporite deposits: the transparent «lower subunit» appears to have undergone ductile-flow deformation», with the development of salt-cored thrusting structures, and the layered «upper subunit» appears to be characterized by brittle deformation. …
Backthrusts and passive roof duplexes in fold-and-thrust belts
2012
Abstract Seismic reflection profiles crossing the area bounded by the M. Kumeta Ridge and the M. Maranfusa-M. Galiello-Rocca Busambra morphostructural feature (central-western Sicily) were used to constrain the deep structural setting of the Sicilian–Maghrebian fold-and-thrust belt (FTB). By integrating seismic, field and well data, we attempted to correlate outcropping and deep-seated contractional structures, shedding light on the internal geometries of the thrust system. Results of the new seismostratigraphic analysis presented in this paper reveal structural variations along the tectonic edifice. This suggests dividing the study area into two sectors: the western sector is characterized…
Tectonic transport directions of the Lycian nappes in southwest Turkey constrained by kinematic indicators
2013
The orientation, asymmetry and cross-cutting relationships of the structures along the contact zone between the Lycian nappes and the Menderes Massif suggest the presence of three deformation phases in the Milas region of southwest Turkey. The first deformation phase (D1) is characterized by a ductile deformation with top-to-the-NE sense of shear. Structural data of the first deformation measured along the uppermost part of the Menderes Massif and the base of the Lycian nappes suggest that the lowermost unit of the Lycian nappes was emplaced initially from southwest to northeast onto the Menderes Massif during the Early Eocene. The second deformation phase (D2) is also ductile in nature and…