370 research outputs found
Caldera unrest driven by CO2-induced drying of the deep hydrothermal system
Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO2-CH4 exchange of 13C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO2-rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO2-infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism
Effectiveness of high dose sublingual immunotherapy to induce a stepdown of seasonal asthma: a pilot study
There is ample evidence to support the efficacy of sublingual immunotherapy (SLIT) on allergic rhinitis, while there is less solid data regarding asthma. We evaluated the effects of a high dose birch SLIT on birch-induced rhinitis and asthma in a controlled study
The Campi Flegrei caldera: unrest mechanisms and hazards
In the last four decades, Campi Flegrei caldera has been the world’s most active
caldera characterized by intense unrest episodes involving huge ground deformation and
seismicity, but, at the time of writing, has not culminated in an eruption. We present a careful
review, with new analyses and interpretation, of all the data and recent research results. We
deal with three main problems: the tentative reconstruction of the substructure; the modelling
of unrest episodes to shed light on possible pre-eruptive scenarios; and the probabilistic
estimation of the hazards from explosive pyroclastic products. The results show, for the first
time at a volcano, that a very peculiar mechanism is generating episodes of unrest, involving
mainly activation of the geothermal system from deeper magma reservoirs. The character and
evolution of unrest episodes is strongly controlled by structural features, like the ring-fault
system at the borders of the caldera collapse. The use of detailed volcanological, mathematical
and statistical procedures also make it possible to obtain a detailed picture of eruptive hazards
in the whole Neapolitan area. The complex behaviour of this caldera, involving interaction
between magmatic and geothermal phenomena, sheds light on the dynamics of the most
dangerous types of volcanoes in the world
Ground deformation analysis at Campi Flegrei (Southern Italy) by CGPS and tide-gauge network
Campi Flegrei caldera is located 15 km west of the
city of Naples, within the central-southern sector of a
large graben called Campanian Plain. It is an active
volcanic area marked by a quasi-circular caldera
depression, formed by a huge ignimbritic eruption
occurred about 37000 years ago. This caldera was
generated by several collapses produced by strong
explosive eruptions (the last eruption, occurred in
1538, built an about 130 m spatter cone called Mt.
Nuovo). Campi Flegrei area periodically experiences
significant deformation episodes, with uplift
phenomena up to more than 3.5 m in 15 years (from
1970 to 1984), which caused during 1983-84 the
temporary evacuation of about 40000 people from the
ancient part of Pozzuoli town.
The deformation field obtainable by CGPS and tidegauge
stations plays an important role for the
modelling and interpretation of volcanic phenomena,
as well as for forecasting purposes.
The structural complexity of the Campi Flegrei area,
together with the evidence of a strong interaction
between magmatic chamber and shallow geothermal
system, calls for a detailed characterization of the
substructure and of magma-water interaction
processes.
The incoming experiment of deep drilling, down to
about 4 km, will give detailed structural and physical
constraints able to resolve the intrinsic ambiguities of
geophysical data and in particular geodetic ones.
In this poster we describe the recent ground
deformations at Campi Flegrei area by means of GPS
technique and tide gauge stations, discussing the
possible interpretations also in light of further
constraints likely coming from the next CFDDP
(Campi Flegrei Deep Drilling) deep drilling experiment
3D change detection analysis of a coastal landslide performed by multi-temporal point clouds comparison
The structure from motion (SfM) photogrammetric technique (FONSTAD et al., 2013) has become a suitable method to obtain high resolution topography data in a wide range of geomorphic environments (PASSALACQUA et al., 2015). SfM is designed to reconstruct the three-dimensional geometry of buildings and objects from randomly acquired images, and represents a low cost option respect to traditional photogrammetric and lidar techniques (FONSTAD et al., 2013). In this way, also the 3D geometry of complex natural surfaces can be achieved with a horizontal and vertical accuracy which depend on the choice of sensor for images acquisition, platform (e.g., UAV, boat, vehicle), and method of assignment of geodetic coordinates to the digital data. In advanced geomorphic applications, repeated photogrammetric surveys at different times allow to detect topographic changes in order to map or monitor erosion, deposition and develop sediment budgets.
In this work we present a 3D change detection analysis related to a coastal landslide occurred on 27th October 2013 along the coastal sector of the Campi Flegrei volcanic district, Southern Italy (ESPOSITO et al., 2015). A total of four photogrammetric surveys have been carried out in about two years (Fig. 1), by using a UAV platform for one survey and boats for the other three. In order to accurately define the exterior orientation of images, a topographic survey was also carried out, measuring a series of natural and artificial ground control points external to the landslide area with a long-range Total Station. Images were processed using Agisoft PhotoScan® (http://www.agisoft.com), and 3D point clouds were compared through the "Multiscale Model to Model Cloud Comparison (M3C2)" plugin (LAGUE et al., 2013) included in CloudCompare open source software (http://www.danielgm.net/cc/). The plugin allowed us to estimate orthogonal distances between multitemporal point clouds as well as uncertainty related to each distance measurement.
SfM processing of each survey resulted in dense point clouds and high-resolution orthophotos. An average coregistration error between clouds was estimated as 11 cm. As output of the M3C2 distance computation we obtained three new clouds in which each point was characterized by distance and uncertainty attributes (Fig. 2). Points corresponding to statistically significant changes were exported and interpolated in ESRI ArcGis® for volume calculation. Volumetric data show that the landslide deposit at cliff toe was progressively eroded by the sea, while landslide scar was affected by a moderate erosion in the first three months after the 2013 landslide event, as well as by a deep erosion between the second and third surveys.
Nevertheless, a negligible eroded volume between 2015 and 2016 surveys was estimated in this area. Deposited sediments decreased through time in the whole landslide area so that, generally, a geomorphic evolution moving towards an equilibrium condition seems to be taking place. The study here described highlights a high potentiality of the SfM and cloud-to-cloud distance computation techniques in geomorphology, both for accurate qualitative and quantitative analysis and for hazard and risk assessment. The studied landslide threats indeed a series of residential buildings located close to the retreating cliff edge
Virtual Surgical Reduction in Atrophic Edentulous Mandible Fractures: A Novel Approach Based on “in House” Digital Work-Flow
Featured Application: Virtual Surgical Planning in Cranio-Facial Traumatology. Atrophic edentulous mandible fractures are a challenge for maxillo-facial surgeons because of low vascularization, low bone regeneration, and lack of occlusion. Whereas occlusion is the main guide in the reduction of mandibular fractures, the aim of our study is to show the advantages of using virtual surgical planning (VSP) in surgery when the occlusal guide is absent. This work is a prospective study that shows the in-house digital workflow for the management of these fractures in the Maxillo-Facial Surgery Unit of Federico II University Hospital of Naples. Four patients who satisfied the criteria were included in the study. For each patient, the same defined CAD/CAM-based was applied. The workflow followed four steps: (1) bone segmentation and virtual reduction of fracture fragments; (2) three-dimensional printing of virtually reduced mandible and modelling of 2.4 reconstruction plate on printed resin model; (3) surgery aided by the pre-formed plate; (4) digital and clinical outcomes analysis. In the last step, a distance colour map was conducted to compare the virtual planning and postoperative CT outcome. In all cases, the discrepancies values between the two images were lower than 1.5 mm, and good clinical outcomes in terms of facial symmetry, absence of sensory disturbance, and possibility of prosthetic rehabilitation were obtained. In conclusion, the VSP, with our in-house workflow brings benefits in the management of atrophic edentulous mandible fractures in terms of the high accuracy of bone repositioning
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