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1.
R. U. Claudi M. Cancian M. Barbieri R. Gratton S. Desidera M. Montalto G. P. Piotto S. Scuderi 《Astrophysics and Space Science》2006,304(1-4):251-251
RATS is an Italian project devoted to Hot Jupiter search with the transit method. A planet transiting in front of a host star can be mimed by several, and well defined, astrophysical phenomena (Brown, 2003). In order to recognize these false alarms we can utilize a preventive strategy to limit false alarm rates and a spectroscopic follow up to refuse no transit candidates. As preventive strategy it is important to develop an accurate target field selection, with well defined requisites, in order to maximize the solar type star numbers and to minimize the risk of possible astrophysical false alarms. 相似文献
2.
Antonio Montalto 《Bulletin of Volcanology》1994,56(3):220-227
Since the last eruption (1888–1890) volcanism at Vulcano, Aeolian Archipelago, southern Tyrrhenian Sea, has taken the form of persistent fumarolic activity. The gas-vapour phases of the geothermal systems are mainly discharged within two restricted areas about 1 km apart from each other, in the northern part of the island. These areas are La Fossa crater, and the beach fumaroles of the Baia di Levante. Fluids released at the two main fumarolic fields display quite different chemical and temperature characteristics, implying different origins. The local seismicity essentially takes the form of discrete shocks of shallow origin (depth1 km) at La Fossa, usually with energy < 1013
ergs. They are thought to be related to the uprise of pressurized hot gases and vapours discharged at the crater fumaroles. The present investigation points to the existence of two principal categories of seismic events (called M-shocks and N-shocks). These are short events (normally < 10 s). M-type shocks are thought to be due to resonance vibrations within the interior of the volcano, probably driven by the excitation of shock-waves within cavities deeply affected by deposition and alteration of self-sealant hydrothermal minerals. N-type events display features that resemble those of volcano-tectonic earthquakes, but have no recognizable S-phases. Here they are tentatively attributed to microfracturing of rocks which have been extensively hydrothermally altered. Results of the present study permit a preliminary conceptual model of the local shallow seismic processes in the framework of geochemical modelling of fumarolic activity and geological inferences from geothermal drilling. 相似文献
3.
Carmelo Cassisi Marco Aliotta Andrea Cannata Placido Montalto Domenico Patanè Alfredo Pulvirenti Letizia Spampinato 《Pure and Applied Geophysics》2013,170(4):529-545
Algorithms searching for similar patterns are widely used in seismology both when the waveforms of the events of interest are known and when there is no a priori-knowledge. Such methods usually make use of the cross-correlation coefficient as a measure of similarity; if there is no a-priori knowledge, they behave as brute-force searching algorithms. The disadvantage of these methods, preventing or limiting their application to very large datasets, is computational complexity. The Mueen–Keogh (MK) algorithm overcomes this limitation by means of two optimization techniques—the early abandoning concept and space indexing. Here, we apply the MK algorithm to amplitude time series retrieved from seismic signals recorded during episodic eruptive activity of Mt Etna in 2011. By adequately tuning the input to the MK algorithm we found eight motif groups characterized by distinct seismic amplitude trends, each related to a different phenomenon. In particular, we observed that earthquakes are accompanied by sharp increases and decreases in seismic amplitude whereas lava fountains are accompanied by slower changes. These results demonstrate that the MK algorithm, because of its particular features, may have wide applicability in seismology. 相似文献
4.
Andrea Cannata Gaetano Giudice Sergio Gurrieri Placido Montalto Salvatore Alparone Giuseppe Di Grazia Rocco Favara Stefano Gresta Marco Liuzzo 《Environmental Earth Sciences》2010,61(3):477-489
Large variations of the CO2 flux through the soil were observed between November 2002 and January 2006 at Mt. Etna volcano. In many cases, the CO2 flux was strongly influenced by changes in air temperature and atmospheric pressure. A new filtering method was then developed
to remove the atmospheric influences on soil CO2 flux and, at the same time, to highlight the variations strictly related to volcanic activity. Successively, the CO2 corrected data were quantitatively compared with the spectral amplitude of the volcanic tremor by cross correlation function,
cross-wavelet spectrum and wavelet coherence. These analyses suggested that the soil CO2 flux variations preceded those of volcanic tremor by about 50 days. Given that volcanic tremor is linked to the shallow (a
few kilometer) magma dynamics and soil CO2 flux related to the deeper (~12 km b.s.l.) magma dynamics, the “delayed similarity” between the CO2 flux and the volcanic tremor amplitude was used to assess the average speed in the magma uprising into the crust, as about
170–260 m per day. Finally, the large amount of CO2 released before the onset of the 2004–2005 eruption indicated a deep ingression of new magma, which might have triggered
such an eruption. 相似文献
5.
Andrea Cannata Giuseppe Di Grazia Marco Aliotta Carmelo Cassisi Placido Montalto Domenico Patanè 《Pure and Applied Geophysics》2013,170(11):1751-1771
Volcanoes generate a broad range of seismo-volcanic and infrasonic signals, whose features and variations are often closely related to volcanic activity. The study of these signals is hence very useful in the monitoring and investigation of volcano dynamics. The analysis of seismo-volcanic and infrasonic signals requires specifically developed techniques due to their unique characteristics, which are generally quite distinct compared with tectonic and volcano-tectonic earthquakes. In this work, we describe analysis methods used to detect and locate seismo-volcanic and infrasonic signals at Mt. Etna. Volcanic tremor sources are located using a method based on spatial seismic amplitude distribution, assuming propagation in a homogeneous medium. The tremor source is found by calculating the goodness of the linear regression fit (R 2) of the log-linearized equation of the seismic amplitude decay with distance. The location method for long-period events is based on the joint computation of semblance and R 2 values, and the location method of very long-period events is based on the application of radial semblance. Infrasonic events and tremor are located by semblance–brightness- and semblance-based methods, respectively. The techniques described here can also be applied to other volcanoes and do not require particular network geometries (such as arrays) but rather simple sparse networks. Using the source locations of all the considered signals, we were able to reconstruct the shallow plumbing system (above sea level) during 2011. 相似文献
6.
L. Spampinato C. Oppenheimer A. Cannata P. Montalto G. G. Salerno S. Calvari 《Bulletin of Volcanology》2012,74(6):1281-1292
Thermal imagery obtained with portable infrared cameras is widely used to track and measure volcanic phenomena. In the case of explosive eruptions, both air and ground-based thermal monitoring have enabled collection of data streams from relatively safe distances. Analysis of these data have enabled the characterisation of different explosive regimes, parameterisation of eruptive plumes, and assessment on the dynamics occurring in the shallow system. Here we explore the suitability of infrared imagers for investigating the short time scale eruptive behaviour of three basaltic volcanoes. We present high-time resolution thermal image data-sets recorded at Etna, Stromboli and Kīlauea volcano. At the time of observations, all three exhibited pulsed degassing. Signal processing of the mean apparent temperature time-series highlights four broad classes of cyclic temperature changes at the three volcanoes based on characteristic time-scales revealed in the periodograms: (1) <15?s, (2) ~20-50?s, (3) ~1-10?min, and (4) 12–90?min. Based on previous studies and integrating time-series results with qualitative visible and thermal observations and, in case of Kīlauea, also with SO2 column amounts in the plume, we hypothesise that short cycles relate mainly to bursting of overpressured gas bubbles at the magma surface, while long cycles might be associated with mechanisms of gas slug formation and ascent, and to the emplacement and drainage of a lava lake. At Kīlauea, slow fluctuations may reflect periodic variations of the lava lake surface level. The data from all three volcanoes reveal superimposition of degassing cycles of different frequencies, suggesting link through common magmatic processes and physical properties. 相似文献
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8.
P. Montalto A. Cannata E. Privitera S. Gresta G. Nunnari D. Patanè 《Pure and Applied Geophysics》2010,167(10):1215-1231
Active volcanoes characterized by open conduit conditions generate sonic and infrasonic signals, whose investigation provides useful information for both monitoring purposes and studying the dynamics of explosive processes. In this work, we discuss the automatic procedures implemented for a real-time application to the data acquired by a permanent network of five infrasound stations running at Mt. Etna volcano. The infrasound signals at Mt. Etna consist in amplitude transients, called infrasound events. The adopted procedure uses a multi-algorithm approach for event detection, counting, characterization and location. It is designed for an efficient and accurate processing of infrasound records provided by single-site and array stations. Moreover, the source mechanism of these events can be investigated off-line or in near real-time by using three different models: (1) Strombolian bubble; (2) resonating conduit and (3) Helmholtz resonator. The infrasound waveforms allow us to choose the most suitable model, to get quantitative information about the source and to follow the time evolution of the source parameters. 相似文献
9.
The benthic invertebrate assemblages and functional feeding groups in different mesohabitats of the Middle Paraná River–floodplain system were analyzed. Benthic invertebrates and bottom sediments were sampled in a secondary channel (center and bank mesohabitats), a temporal marginal fluvial wetland adjacent to the river, an isolated lake and a connected lake during low water level. Cluster analysis of average invertebrate densities based on the Bray Curtis dissimilarity index yielded a group composed by the mesohabitats with higher species richness, the floodplain lakes, banks mesohabitats and the wetland. The center mesohabitat of the main channel characterized by sandy sediments with low organic matter content and the lowest invertebrate densities and species richness was classified separately. Alpha diversity increased from the center mesohabitat (6 taxa) to the adjacent wetland (71 taxa), and were similar between the floodplain lakes (24 and 22 taxa) and the river bank mesohabitat (24 taxa). Gamma and beta diversities (Whittaker index) were 92 and 2.19, respectively. The highest turnover of taxa was between the river and the other mesohabitats and the lowest between floodplain lakes. Detrended correspondence analysis (DCA) showed a clear separation of wetland and banks from other mesohabitats (axis 1 and 2 explained 52.25% variance) explained by shredders and collector-filterers. The other mesohabitats were arranged in a gradient from the main channel mostly related to collector-gatherers to the connected lake and the isolated lake that were mostly characterized by predators and scrapers. The invertebrate assemblage complexity and functional feeding groups composition increased in the lateral dimension, from the center of the main channel to the temporal marginal fluvial wetland due to the influences of the spatial heterogeneity caused by different sources of organic matter inputs. 相似文献
10.