La sequenza sismica nel versante nord-occidentale dell'Etna del 19-27 Dicembre 2009 : evidenze di ricarica magmatica profonda?

E’ stata analizzata la sequenza sismica che ha interessato il versante nord-occidentale dell’Etna nel periodo 19-27 dicembre 2009 (Fig. 1). Essa è stata caratterizzata da oltre 400 scosse di magnitudo compresa tra 1.0 e 4.8, localizzate ad una profondità tra 20 e 30 km, con un rilevante rilascio energetico, come si osserva dalla distribuzione temporale del numero delle scosse e dell’energia ad esse associata nel tempo (Fig. 2). È interessante notare come l’energia rilasciata durante la sequenza risulti essere quasi il triplo dell’energia del periodo sineruttivo 2008, pur essendo pressoché uguale il numero di scosse registrate. In questo settore dell’area etnea, caratterizzato da sismicità profonda, poco frequente e di modesta energia, la modalità di rilascio sismico della sequenza in oggetto costituisce un elemento di novità. Infatti, più del 50% delle scosse si sono verificate nel corso delle prime 24 ore, come tipicamente osservato nel corso di sciami vulcanici sineruttivi. E’ importante evidenziare che nell’area etnea eventi sismici con profondità focali comprese tra i 10 e i 30 km vengono considerati dei veri e propri “markers” di attività vulcanica (e.g. Puglisi et al., 2001), in quanto si verificano abbastanza regolarmente durante i periodi intra-eruttivi e possono essere messi in relazione con i meccanismi di ricarica magmatica (e.g. Bonaccorso, 2001). Essi sono principalmente localizzati nei settori occidentale e meridionale del vulcano lungo strutture orientate NO-SE e NNO-SSE e, occasionalmente, lungo strutture orientate NE-SO (Patanè et al., 2004). Pertanto è ragionevole ipotizzare che il fenomeno oggetto del presente studio possa essere ricondotto ad una fase di ricarica profonda del sistema magmatico etneo

New results from the NUMEN project

NUMEN aims at accessing experimentally driven information on Nuclear Matrix Elements (NME) involved in the half-life of the neutrinoless double beta decay (0νββ), by high-accuracy measurements of the cross sections of Heavy Ion (HI) induced Double Charge Exchange (DCE) reactions. First evidence about the possibility to get quantitative information about NME from experiments is found for the (18O,18Ne) and (20Ne,20O) reactions. Moreover, to infer the neutrino average masses from the possible measurement of the half-life of 0νββ decay, the knowledge of the NME is a crucial aspect. The key tools for this project are the high resolution Superconducting Cyclotron beams and the MAGNEX magnetic spectrometer at INFN Laboratori Nazionali del Sud in Catania (Italy). The measured cross sections are extremely low, limiting the present exploration to few selected isotopes of interest in the context of typically low-yield experimental runs. A major upgrade of the LNS facility is foreseen in order to increase the experimental yield of at least two orders of magnitude, thus making feasible a systematic study of all the cases of interest. peerReviewe

Volcanic-tectonic seismicity at Stromboli (2005–2016)

The seismicity of Stromboli comprises explosion-quakes, volcanic tremor and volcano-tectonic (VT) events.We applied the double-difference approach of Waldhauser and Ellsworth (2000) on 42 VT events recorded during 2005–2016 in order to improve their standard locations. This approach has allowed to cluster hypocentres in two seismogenic sectors (G1 and G2), respectively, located inside and south of Stromboli at depths of 3.5–6 and 10–12 km. The seismicity belonging to G1 is located between the deep and intermediate magma storages of Stromboli and seems to precede the 2007 and 2014 effusive eruptions. This suggests that faulting episodes occur as a response to local stress linked to the pressurization of the magmatic system caused by magma ascent.Published1-64V. Processi pre-eruttiviJCR Journa

The December 2015 Mount Etna eruption: An analysis of inflation/deflation phases and faulting processes

WOS: 000403135300003During the first days of December 2015, there were four paroxysmal events at the "Voragine" crater on Mount Etna, which were among the most violent observed during the last two decades. A few days after the "Voragine" paroxysms, the Pernicana - Provenzana fault system, located near the crater area, underwent an intense seismic swarm with a maximum "local" magnitude M-L of 3.6. This paper investigates the relationship between the eruptive phenomenon and the faulting process in terms of Coulomb stress changes. The recorded seismicity is compatible with a multicausal stress redistribution inside the volcano edifice, occurring after the four paroxysmal episodes that interrupted the usual trend of inflation observed at Mt. Etna. The recorded seismicity falls within the framework of a complex chain of various and inter correlated processes that started with the inflation preparing the "Voragine" magmatic activity. This was followed with the rapid deflation of the volcano edifice during the paroxysmal episodes. We determined that the recorded deflation was not the direct cause of the seismic swarm. In fact, the associated Coulomb stress change, in the area of seismic swarm, was of about 1 [bar]. Instead, the fast deflation caused the rarely observed inversion of dislocation in the eastern flank at the same time as intense hydrothermal activity that, consequently, underwent an alteration. This process probably reduced the friction along the fault system. Then, the new phase of inflation, observed at the end of the magmatic activity, triggered the faulting processes. (C) 2017 Elsevier Ltd. All rights reserved

Seismological and structural constraints on the 2011–2013, Mmax 4.6 seismic sequence at the south-eastern edge of the Calabrian arc (North-eastern Sicily, Italy)

Between June 2011 and September 2013, the Nebrodi Mountains region was affected by a seismic swarm consisting of > 2700 events with local magnitude 1.3 ≤ ML ≤ 4.6 and located in the 5–9 km depth interval. The seismic swarm defines a seismogenetic volume elongated along the E-W direction and encompasses the NW-SE-oriented tectonic boundary between the Calabrian arc (north-eastward) and the Sicilide units (south-westward). By exploring the recent tectonic deformation and the seismic behavior of the region, this study aims at providing additional constraints on the seismogenetic faults at the southern termination of the Calabrian arc. Waveform similarities analysis allowed observing that ~ 45% of the whole dataset can be grouped into six different families of seismic events. Earthquake multiplet families are mainly located in the eastern part of the seismogenetic volume. We suggest that such a feature is responsive to the lateral lithological variations as highlighted by geology (at the surface) and P-wave seismic tomography (at depth of 10 km). Stress tensor inversions performed on FPSs indicate that the investigated region is currently subject to a nearly biaxial stress state in an extensional regime, such that crustal stretching occurs along both NW-SE and NE-SW directions. Accordingly, mesoscale fault geometries and kinematics analyses evidence that a younger normal faulting stress regime led to a tectonic negative inversion by replacing the pre-existing strike-slip one. Based on our results and findings reported in recent literature, we refer such a crustal stretching to mantle upwelling process (as evidenced by diffuse mantle-derived gas emissions) coupled with a tectonic uplift involving north-eastern Sicily since Middle Pleistocene. Moreover, seismic swarms striking the region would be related to the migration of mantle and sub-crustal fluids toward the surface along the complex network of tectonic structures cutting the crust and acting as pathways.Published56-672T. Deformazione crostale attivaJCR Journa

Serological diagnosis of bovine brucellosis using B. melitensis strain B115

Bovine brucellosis is diagnosed by official tests, such as Rose Bengal plate test (RBPT) and Complement Fixation test (CFT). Both tests detect antibodies directed against the lipolysaccharide (LPS) of Brucella cell wall. Despite their good sensitivity, those tests do not discriminate between true positive and false positive serological reactions (FPSR), the latter being generated by animals infected with other Gram negative microorganisms that share components of Brucella LPS. In this study, an antigenic extract from whole Brucella melitensis B115 strain was used to set up an ELISA assay for the serological diagnosis of bovine brucellosis. A total of 148 serum samples from five different groups of animals were tested: Group A: 28 samples from two calves experimentally infected with Yersinia enterocolitica O:9; Group B: 30 samples from bovines infected with B. abortus; Group C: 50 samples from brucellosis-free herds; Group D: 20 samples RBPT positive and CFT negative; Group E: 20 samples both RBPT and CFT positive. Group D and Group E serum samples were from brucellosis-free herds. Positive reactions were detected only by RBPT and CFT in calves immunized with Y. enterocolitica O:9. Sera from group B animals tested positive also in the ELISA assay, whereas sera from the remaining groups were all negative. The results obtained encourage the use of the ELISA assay to implement the serological diagnosis of brucellosis