Analysis of sustained long-period activity at Etna Volcano, Italy

Following the installation of a broadband network on Mt. Etna, sustained Long- Period (LP) activity was recorded accompanying a period of total quiescence and the subsequent onset of the 2004–2005 effusive episode. From c. about 56000 events detected by an automatic classification procedure, we analyse a subset of about 3000 signals spanning the December 17th, 2003–September 25th, 2004, time interval. LP spectra are characterised by several, unevenly-spaced narrow peaks spanning the 0.5–10 Hz frequency band. These peaks are common to all the recording sites of the network, and different from those associated with tremor signals. Throughout the analysed time interval, LP spectra and waveforms maintain significant similarity, thus indicating the involvement of a non-destructive source process that we interpret in terms of the resonance of a fluid-filled buried cavity. Polarisation analysis indicates radiation from a non-isotropic source involving large amounts of shear. Concurrently with LP signals, recordings from the summit station also depict Very-Long-Period (VLP) pulses whose rectilinear motion points to a region located beneath the summit craters at depths ranging between 800 and 1100 m beneath the surface. Based on a refined repicking of similar waveforms, we obtain robust locations for a selected subset of the most energetic LP events from probabilistic inversion of travel-times calculated for a 3D heterogenous structure. LP sources cluster in a narrow volume located beneath the summit craters, and extending to a maximum depth of ≈800 m beneath the surface. No causal relationships are observed between LP, VLP and tremor activities and the onset of the 2004–2005 lava effusions, thus indicating that magmatic overpressure played a limited role in triggering this eruption. These data represent the very first observation of LP and VLP activity at Etna during non-eruptive periods, and open the way to the quantitative modelling of the geometry and dynamics of the shallow plumbing system

The shallow magma pathway geometry at Mt. Etna volcano

A fundamental goal of volcano seismology is to understand the dynamics of active magmatic systems in order to assess eruptive behavior and the associated hazard. Imaging of magma conduits, quantification of magma transport and investigation of long-period seismic sources, together with their temporal variations, are crucial for the comprehension of eruption-triggering mechanisms. At Mt. Etna volcano, several intense episodes of tremor activity were recorded during 2007, in association with strombolian activity and/or intense fire fountaining episodes occurring from the South East Crater (SEC). The locations of the tremor sources and of the long-period seismic events are used here to constrain both the area and the depth range of magma degassing, highlighting the geometry of the shallow conduits feeding SEC. The imaged conduits consist of two connected resonating dike-like bodies, NNW-SSE and NW-SE oriented, extending from sea level to the surface. In addition, we show how tremor, long-period (LP) and very-long-period (VLP) event locations and signatures reflect pressure fluctuations in the plumbing system associated with the ascent/discharge of gas-rich magma linked to the lava fountains. The evidence here reported, also corroborated by ground deformation variations, can help develop a better prediction and early-warning system for those eruptions (effusive or explosive) that apparently manifest no clear precursors

Rapamycin inhibits mTOR/p70S6K activation in CA3 region of the hippocampus of the rat and impairs long term memory

The present study was aimed at establishing whether the mTOR pathway and its downstream effector p70S6K in CA3 pyramidal neurons are under the modulation of the cholinergic input to trigger the formation of long term memories, similar to what we demonstrated in CA1 hippocampus. We performed in vivo behavioral experiments using the step down inhibitory avoidance test in adult Wistar rats to evaluate memory formation under different conditions. We examined the effects of rapamycin, an inhibitor of mTORC1 formation, scopolamine, a muscarinic receptor antagonist or mecamylamine, a nicotinic receptor antagonist, on short and long term memory formation and on the functionality of the mTOR pathway. Acquisition was conducted 30 min after i.c.v. injection of rapamycin. Recall testing was performed 1h, 4h or 24h after acquisition. We found that (1) mTOR and p70S6K activation in CA3 pyramidal neurons were involved in long term memory formation; (2) rapamycin significantly inhibited mTOR and of p70S6K activation at 4h, and long term memory impairment 24h after acquisition; (3) scopolamine impaired short but not long term memory, with an early increase of mTOR/p70S6K activation at 1h followed by stabilization at longer times; (4) mecamylamine and scopolamine co-administration impaired short term memory at 1h and 4h and reduced the scopolamine-induced increase of mTOR/p70S6K activation at 1h and 4h; (5) mecamylamine and scopolamine treatment did not impair long term memory formation; (6) unexpectedly, rapamycin increased mTORC2 activation in microglial cells. Our results demonstrate that in CA3 pyramidal neurons the mTOR/p70S6K pathway is under the modulation of the cholinergic system and is involved in long-term memory encoding, and are consistent with the hypothesis that the CA3 region of the hippocampus is involved in memory mechanisms based on rapid, one-trial object–place learning and recall. Furthermore, our results are in accordance with previous reports that selective molecular mechanisms underlie either short term memory, long term memory, or both. Furthermore, our discovery that administration of rapamycin increased the activation of mTORC2 in microglial cells supports a reappraisal of the beneficial/adverse effects of rapamycin administration

Geophysical investigations of the plumbing system of Stromboli volcano (Aeolian Islands, Italy)

In this work, we report the results of an integrated approach using both seismological and geodetic data provided by the INGV-CT (Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania) Stromboli volcano monitoring systems, in order to improve the knowledge of its plumbing system. In particular, we investigated the relationships between the June 1999 seismic swarm, occurring in the area of Stromboli, and the possible activation of the NE-SW oriented volcano-tectonic structure. We analyzed this seismic swarm proposing new locations and a morphological analysis of the waveforms. This approach allowed us to demonstrate that there are relationships between the tectonic activity near Stromboli and the rising of magma. This evidence supports the hypothesis that during the 1999 swarm an intrusive process started from a crustal level where earthquakes were located (about 10-15 km b.s.l.). As already testified by other similar episodes (deformation anomaly recorded between December 1994 and March 1995 after the November 1994 swarm), months after the 1999 seismic activity, the tiltmeters and the GPS permanent stations deployed in Stromboli, showed slow variations over three months (May-July 2000). We performed an analytical inversion of these geodetic observations and found that the modelled sources are characterized by NE-SW trend, compatible with the regional faults cutting the volcano. The modelled sources could represent the rising pathway connecting the "deep" plumbing system (about 10-15 km b.s.l.) to the "shallow" one located in the body of the Stromboli volcano (about 500 m a.s.l.). These new evidences support the hypothesis of the existence of a simple plumbing system with different levels of magma storage, where batches of magma are periodically pushed up along the main NE-SW tectonic trend. (C) 2008 Elsevier B.V. All rights reserved

Space-Time Evolution of Magma Storage and Transfer at Mt. Etna Volcano (Italy): the 2015-2016 Re-Awakening of Voragine Crater'

The eruptions of December 2015 and May 2016 at Voragine crater were among the most explosive recorded during the last two decades at Mt. Etna volcano. Here, we present data coming from geophysics (infrasound, LP, VLP, volcanic tremor, VT earthquakes, ground deformations) and petrology (textural and micro-analytical data on plagioclase and olivine crystals) to investigate the pre-eruptive magma storage and transfer dynamics leading to these exceptional explosive eruptions. Integration of all the available data has led us to constrain chemically, physically and kinetically the environments where magmas were stored before the eruption, and how they have interacted during the transfer en-route to the surface. Although the evolution and behavior of volcanic phenomena at the surface was rather similar, some differences in storage and transfer dynamics were observed for 2015 and 2016 eruptions. Specifically, the 2015 eruptions have been fed by magmas stored at shallow levels that were pushed upward as a response of magma injections from deeper environments, whereas evidence of chemical interaction between shallow and deep magmatic environments becomes more prominent during the 2016 eruptions. Main findings evidence the activation of magmatic environments deeper than those generally observed for other recent Etnean eruptions, with involvement of deep basic magmas that were brought to shallow crustal levels in very short timescales (∼1 month). The fast transfer from the deepest levels of the plumbing system of basic, undegassed magmas might be viewed as the crucial triggering factor leading to development of exceptionally violent volcanic phenomena even with only basic magma involved

Advances in the study of geophysical signals from Mt. Etna volcano.

Long-period seismic signals, including LP events and tremor, observed on many volcanoes worldwide, may play a crucial role in the forecasting of volcanic eruptions as these signals are direct indicators of sub-surface magma dynamics. Their location is widely agreed to be useful for mapping the extension and geometry of the plumbing system and also for quantifying pressure transients caused by resonance or movement of fluids along the conduits. At Mt. Etna detailed investigations on these signals started systematically only after the installation of a broad-band seismic network (since 2003). Thereafter, we present the main results recently obtained on this volcano by analysing tremor, LP and VLP events during two eruptive episodes in the second half of 2007. We also discuss results of cross analysis performed between tremor and gravity sequences acquired simultaneously at Mt. Etna during the 2002-03 eruption and during the December 2005-January 2006 period of quiescence. We detected common anomalies which are indicative of a quasi-closed system, becoming progressively enriched in volatiles. These studies, carried out in the framework of the VOLUME Project, provide new insight into the shallow plumbing system of Etna and grant valuable tools for volcanic hazard forecasting and risk mitigation

Surveillance of enteric virus infections in a neonatal intensive care unit.

Objective. To investigate the epidemiology of neonatal viral gastroenteritis compared to the circulation of enteric viruses in children, 109 newborns in the NICU of Mother and Child Department and 214 children with enteritis admitted to the \u201cG. Di Cristina\u201d Children\u2019s Hospital in Palermo were monitored for Rotavirus, Adenovirus, Astrovirus and Norovirus infections. Methods. Stool samples were examined by EIA to detect viral antigens. Rotavirus strains were subjected to P- and G-typing. Results. A Norovirus strain was detected in one neonatal stool specimen whereas an astrovirus strain was dectected in two neonatal specimens. No Rotavirus or Adenovirus infection was identified among the newborn infants, while Rotavirus infections were detected in 24.8% of the symptomatic children. Type G4P[8] constituted 43.4% of the Rotavirus strains, followed by G2P[4] (18.9%), G3P[8] (17%), G1P[8] (13.2%) and G9P[8] (1.9%). Overall, Norovirus, Adenovirus and Astrovirus strains were responsible for 15.4% of infections in the paediatric population with diarrhoea. Conclusions. Viruses are diffuse agents of infection in children with enteritis. Virological tests have to be performed to diagnose enteric infections in the paediatric population. Maternal immunity to common Rotavirus strains combined with the limited circulation of the emerging G9 Rotavirus type among our population may account for the absence of Rotavirus infections in newborn infants

Volcanic tremor at Mt. Etna, Italy, preceding and accompanying the eruption of July-August, 2001

The July 17 – August 9, 2001 flank eruption of Mt. Etna was preceded and accompanied by remarkable changes in volcanic tremor. Based on the records of stations belonging to the permanent seismic network deployed on the volcano, we analyze amplitude and frequency content of the seismic signal. We find considerable changes in the volcanic tremor which mark the transition to different styles of eruptive activity, e.g., lava fountains, phreatomagmatic activity, Strombolian explosions. In particular, the frequency content of the signal decreases from 5 Hz to 3 Hz at our reference station ETF during episodes of lava fountains, and further decreases at about 2 Hz throughout phases of intense lava emission. The frequency content and the ratios of the signal amplitude allow us to distinguish three seismic sources, i.e., the peripheral dike which fed the eruption, the reservoir which fed the lava fountains, and the central conduit. Based on the analysis of the amplitude decay of the signal, we highlight the migration of the dike from a depth of ca. 5 km to about 1 km between July 10 and 12. After the onset of the effusive phase, the distribution of the amplitude decay at our stations can be interpreted as the overall result of sources located within the first half kilometer from the surface. Although on a qualitative basis, our findings shed some light on the complex feeding system of Mt. Etna, and integrate other volcanological and geophysical studies which tackle the problem of magma replenishment for the July–August, 2001 flank eruption. We conclude that volcanic tremor is fundamental in monitoring Mt. Etna, not only as a marker of the different sources which act within the volcano edifice, but also of the diverse styles of eruptive activity

Volcano monitoring and early warning on Mt Etna, Italy, using volcanic tremor – Methods and technical aspects

Recent activity on Mt Etna was characterized by 25 lava fountains occurred on Mt Etna in 2011 and the first semester of 2012. In summer 2012 volcanic activity in a milder form was noticed within the Bocca Nuova crater, before it came to an essential halt in August 2012. Together with previous unrests (e. g., in 2007-08) these events offer rich material for testing automatic data processing and alert issue in the context of volcano monitoring. Our presentation focuses on the seismic background radiation – volcanic tremor – which has a key role in the surveillance of Mt Etna. From 2006 on a multi-station alert system exploiting STA/LTA ratios, has been established in the INGV operative centre of Catania. Besides, also the frequency content has been found to change correspondingly to the type of volcanic activity, and can thus be exploited for warning purposes. We apply Self Organizing Maps and Fuzzy Clustering which offer an efficient way to visualize signal characteristics and its development with time. These techniques allow to identify early stages of eruptive events and automatically flag a critical status before this becomes evident in conventional monitoring techniques. Changes of tremor characteristics are related to the position of the source of the signal. Given the dense seismic network we can base the location of the sources on distribution of the amplitudes across the network. The locations proved to be extremely useful for warning throughout both a flank eruption in 2008 as well as the 2011 lava fountains. During all these episodes a clear migration of tremor sources towards the eruptive centres was revealed in advance. The location of the sources completes the picture of an imminent volcanic unrest and corroborates early warnings flagged by the changes of signal characteristics. Automatic real time data processing poses high demands on computational efficiency, robustness of the methods and stability of data acquisition. The amplitude based multi-station approach is not sensitive to the failure of single stations and therefore offers a good stability. On the other hand, the single station approach, exploiting unsupervised classification techniques, limits logistic efforts, as only one or few key stations are necessary. A common characteristics of both strategies is their robustness to disturbances (undesired transients like earthquakes, noise, short gaps in the continuous data flow). False alarms were not encountered so far. A critical issue it the reliability of data storage and access. Therefore, a specific hardware cluster architecture has been proposed for failover protection, including a Storage Area Network system. We present concepts of the software architectures which allow easy data access following predefined user policies. We also envisage the integration of seismic data and those originating from other scientific fields (e. g., volcano imagery, geochemistry, deformation, gravity, magneto-telluric). This will facilitate cross-checking of evidences encountered from the single data streams, in particular allow their immediate verification with respect to ground truth

Detection of volcano unrest from multiparameter pattern classification

Short-term forecasting of volcanic unrest requires high-rate/continuous data acquisition and monitoring of multidisciplinary data. Volcano Observatories worldwide usually adopt various tools for the automatic processing of geophysical and geochemical data streams to detect changes heralding impending eruptive activity. Here we discuss the application to multivariate data sets of a free software named KKAnalysis. The software is one of the data mining tools of the European MEDiterrranean Supersite Volcanoes (MED­SUV) project, and carries out the pattern classification of data of whatever nature provided in numerical format. We explain how this software works combining Self-Organizing Maps and fuzzy clustering. Beside numerical log files, changes of pattern characteristics are visualized as output of KKAnalysis in graphical form, by creating a sequence of colored symbols. This convenient color code highlights the development in time of the characteristics of whatever multidimensional feature vector. We also present results of applications to seismic data (volcanic tremor), in-soil radon activity, and ambient parameters (barometric pressure and air temperature measurements acquired at the same site of the radon data). We explore these applications at Mt. Etna, Italy, in time spans of various duration (from months to years), in which eruptive activity ranged from short-lived (usually from tens of minutes to hours) lava fountains to long-lasting (from months to years) lava effusions