75 research outputs found
Tentative recognition of the Italian seismic zones most prone to next strong earthquakes (as a tool for reduction of seismic risk)
A large portion of the building heritage in Italy has not been realized to resist the seismic
shaking caused by earthquakes occurred in the past. Thus, the limited economic resources now
available are largely insufficient to obtain a significant reduction of the seismic risk throughout the
whole country. A way to achieve such objective might be identified by exploiting the fact that most
probably in the next tens of years only few Italian zones will be hit by strong earthquakes and that,
consequently, for such period the restoration of weak buildings and critical infrastructures will be
urgent only in a very limited portion of the national territory. Thus, if the present scientific
knowledge allowed us to reliably identify the location of the next major shocks, a significant
reduction of the of seismic risk in Italy could become economically and operationally feasible.
The hope of realizing such very attractive possibility should strongly increase the attention of
Civil Protection authorities towards the researches that may provide the information cited above. As
a first contribution towards that objective, this report describes a procedure that might allow the
recognition of the Italian zone most prone to the next strong earthquake
Terremoti avvenuti in Appennino centrale nel periodo Agosto-Ottobre 2016: un chiaro esempio di come le attuali carte di pericolositĂ sismica sottovalutano il problema
Le attuali carte di pericolositĂ in Italia sono basate sullo studio della sismicitĂ passata condotto con metodologie statistiche (Cornell, 1968; McGuire, 1978). In vari articoli (si vedano, ad esempio, Viti et al., 2009 e Mantovani et al., 2012, 2013, 2014a, 2014b), il gruppo di ricerca geofisica che fa capo al Dipartimento di Scienze Fisiche, della Terra e dell’Ambiente (DSFTA) dell’UniversitĂ di Siena ha sottolineato che i risultati ottenuti da tale tipo di approccio possono portare a significative sottovalutazioni della pericolositĂ
Seismotectonics of the Padanian region and surrounding belts: which driving mechanism?
It is argued that the complex tectonic pattern observed in the study area can plausibly
be explained as an effect of the kinematics of the Iberia and Adria blocks, induced
by the NNE ward motion of Africa and the roughly westward motion of the Anatolian-
Aegean system with respect to Eurasia. These boundary conditions cause the
constrictional regime which is responsible for the observed shortening processes in
the Padanian region and Western Alps. The proposed dynamic context can plausibly
account for the peculiar distribution of major seismic sources, located in the northern
Apennines, the Giudicarie fault system, the offshore of the western Ligurian
coast and the Swiss Alps. The observed tectonic pattern in Western Europe and the
study area can hardly be reconciled with the implications of the roughly NWward
convergence between Africa and Eurasia proposed by global kinematic models,
whereas it is compatible with the alternative Africa-Eurasia kinematics and plate
mosaic proposed by [1]
Best strategy for the development of a seismic prevention plan
An effective mitigation of seismic risk in Italy can hardly be obtained without a tentative recognition of few priority
zones, where the limited resources available in the short term can be concentrated. A reliable recognition of the zones where the probability of major earthquakes is highest must be carried out by a deterministic approach, exploiting the profound knowledge acquired about the present seismotectonic context in the zones involved. Some years ago, this kind of procedure led us to identify the central-northern Apennines (i.e. the zone hit by the recent major earthquakes, 2016 and 2017) as the Italian area most prone to next strong shocks. The reliability of the methodology here proposed is also supported by the fact that the implications of the adopted tectonic setting can provide plausible and coherent explanations for the spatio-temporaldistribution of major earthquakes in the central Mediterranean area in the last six centuries
Possible location of the next major earthquakes in the northern Apennines: present key role of the Romagna-Marche-Umbria wedge
It is argued that in some zones of the Northern Apennines, in particular the
Rimini-Ancona thrust system, the Romagna Apennines and the Alta Valtiberina
trough, the probability of major earthquakes is now higher than in other
Apennine zones. This hypothesis is suggested by the comparison of the
present short-term kinematics of the Romagna-Marche-Umbria wedge in the
Northern Apennines, deduced by the distribution of major shocks in the last
tens of years, with the previous repeated behavior of the same wedge, evidenced
by the distribution of major earthquakes in the last seven centuries.
The seismotectonics of the Apennine region here considered is closely connected
with the larger context that involves the progressive migration (from
south to north) of seismicity along the peri-Adriatic zones. The information
provided by this study can be used to better manage the resources for prevention
in Italy
Non-permanent GPS data for regional-scale kinematics: reliable deformation rate before the 6 April, 2009, earthquake in the L'Aquila area
A GPS-based geodetic study at a regional scale requires the availability of a dense network that is characterized by 10 km to 30 km spacing, typically followed in a few continuous GPS stations (CGPSs) and several non-permanent GPS stations (NPSs). As short observation times do not allow adequate noise modeling, NPS data need specific processing where the main differences between NPSs and CGPSs are taken into account: primarily time-series length and antenna repositioning error. The GPS data collected in the 1999-2007 time-span from non-permanent measurement campaigns in the central Apennine area (Italy) that was recently hit by the Mw 6.3 L'Aquila earthquake (April 6, 2009) are here further analyzed to compute a reliable strain-rate field at a regional scale. Moreover, areas characterized by different kinematics are recognized, and a complete characterization of the regional-scale kinematics is attempted. These new data can be interpreted as indicators from the viewpoint of seismic risk assessment
Present Tectonic Setting and Spatio-Temporal Distribution of Seismicity in the Apennine Belt
In previous papers, we have argued that a close connection may exist between the discontinuous
northward displacement of the Adria plate and the spatio-temporal distribution of major earthquakes
in the periAdriatic regions [1]-[3]. In particular, five seismic sequences are tentatively recognized
in the post 1400 A.D. seismic history, each characterized by a progressive migration of
major shocks along the eastern (Hellenides, Dinarides), western (Apennines) and northern (Eastern
Southern Alps) boundaries of Adria. In this work, we describe an attempt at gaining insights
into the short-term evolution of the strain field that underlies the migration of seismicity in the
Apennine belt. The results of this study suggest that seismicity in the study area is mainly conditioned
by the fact that the outer (Adriatic) sector of the Apennine belt, driven by the Adria plate, is
moving faster than the inner (Tyrrhenian) belt. This kinematics is consistent with the observed
Pleistocene deformation pattern and the velocity field inferred by GPS data. The spatio-temporal
distribution of major shocks during the last still ongoing seismic sequence (post 1930) suggests
that at present the probability of next major shocks is highest in the Northern Apennines. Within
this area, we suggest that seismic hazard is higher in the zones located around the outer sector of
the Romagna-Marche-Umbria units (RMU), since that wedge is undergoing an accelerated relative
motion with respect to the inner Apennine belt. This hypothesis may also account for the pattern
of background seismicity in the Northern Apennines. This last activity might indicate that the Upper
Tiber Valley fault system is the most resisted boundary sector of the RMU mobile wedge, implying
an higher probability of major earthquakes
Idiopathic and secondary osteonecrosis of the femoral head show different thrombophilic changes and normal or higher levels of platelet growth factors
BACKGROUND AND PURPOSE:
Thrombophilia represents a risk factor both for idiopathic and secondary osteonecrosis (ON). We evaluated whether clotting changes in idiopathic ON were different from corticosteroid-associated ON. As platelet-rich plasma has been proposed as an adjuvant in surgery, we also assessed whether platelet and serum growth factors were similar to those in healthy subjects.
METHODS:
18 patients with idiopathic ON and 18 with corticosteroid-associated ON were compared with 44 controls for acquired and inherited thrombophilia. Platelet factor 4 (PF4), transforming growth factor-β1, platelet-derived growth factor-BB (PDGF-BB), and vascular endothelial growth factor were assayed in the supernatants of thrombin-activated platelets, in platelet lysates, and in serum from 14 ON patients and 10 controls.
RESULTS:
Idiopathic ON patients had higher plasminogen levels (median 118%) than controls (101%) (p = 0.02). Those with corticosteroid-associated ON had significantly higher D-dimer (333 ng/mL) and lower protein C levels (129%) than controls (164 ng/mL, p = 0.004; 160%, p = 0.02). The frequency of inherited thrombophilia was not different from the controls. No statistically significant differences were found between idiopathic and corticosteroid-associated ON. 20 of the 36 ON patients were smokers. (The controls were selected from smokers because nicotine favors hypercoagulability). ON patients had significantly higher serum PF4 levels (7,383 IU/mL) and PDGF-BB levels (3.1 ng/mL) than controls (4,697 IU/mL, p = 0.005; 2.2 ng/mL, p = 0.02).
INTERPRETATION:
Acquired hypercoagulability was common in both ON types, but the specific changes varied. The release of GF from platelets was not affected, providing a biological basis for platelet-rich plasma being used as an adjuvant in surgical treatment
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