The 1906 eruption of Vesuvius: from magmatic to phreatomagmatic activity through the flashing of a shallow depth hydrothermal system     

Antonella Bertagnini  Patrizia Landi  Roberto Santacroce  Alessandro Sbrana 《Bulletin of Volcanology》1991,53(7):517-532

The April 1906 eruption of Vesuvius is the type-example of the final eruptions that close the short cycles of semi-persistent activity that characterized the volcano in the 1631–1944 period. The eruption had a marked explosive character that accompanied the emission of lava from several vents on the southern slopes of the volcano. The observed sequence of events was characterized by repeated fluctuations of the magma level within the conduit, by large lava fountains, by conduit partial collapses, and by the final explosive decapitation of the summit cone. Contemporary chronicles, although frequently contradictory, allow reconstruction of the eruption, which can be divided into four main phases: (1) lateral lava effusions; (2) lava fountains; (3) gas-pyroclasts column; (4) low dense clouds. Pyroclastic deposits of the Monte Somma ridge and northeastern slope can be related to observed and described events and mainly refer to the 2nd and 3rd phases. The increase in the degree of fragmentation of the juvenile component together with the marked increase of the lithic component and morphologic evidence emphasize the repeated occurrence of magmawater interaction. This was most spectacular in the 3rd phase of the eruption in which, after the decapitation of the cone, a high gas-pyroclasts eruption column was formed. Because of the nature of the lithic fragments (mainly hydrothermally altered and metasomatic rocks), the huge amount of steam, and the high lithic/juvenile ratio, it is unlikely that the largest part of the energy in play was related to the contact between magma and cold phreatic water. We suggest that most of the steam involved in this phase of the eruption came from flashing of the hydrothermal system connected to the very shallow feeding system of the volcano and formed as a consequence of repeated subsurface intrusions between 1872 and 1906. Juvenile products were ejected through the eruption, and represent (at least) two different magma bodies: the first (older) was erupted during the initial phase of the eruption and was exhausted at the beginning of the lava fountains phase, when fresh magma was involved in the eruption.  相似文献   

Search for Gamma Ray Bursts of energy Eγ ≥10 GeV and Eγ ≥ 100 TeV in correlation with BATSE events     

M. Aglietta  B. Alessandro  P. Antonioli  F. Arneodo  L. Bergamasco  M. Bertaina  A. Campos Fauth  A. Castellina  C. Castagnoli  A. Chiavassa  G. Cini  B. D'Ettorre Piazzoli  G. Di Sciascio  W. Fulgione  P. Galeotti  P. L. Ghia  M. Iacovacci  G. Mannocchi  C. Melagrana  C. Morello  G. Navarra  L. Riccati  O. Saavedra  G. C. Trinchero  P. Vallania  S. Vernetto 《Astrophysics and Space Science》1995,231(1-2):351-354

We present the results of a search for Gamma Ray Bursts at energies E 10 GeV and E 100 TeV made by the EAS-TOP Air Shower Array in correlation with 50 events detected by BATSE in the last 3 years.This analysis gives an indication of the sensitivity of air shower arrays in the detection of GRBs at energies beyond the range seen by satellite experiments.  相似文献   

PAssive COastal TOMography: an Innovative Approach for the Remote Monitoring of Sea Temperature     

Enrico De  Marinis  Paola Picco  Alessandro Crise  Otello Gasparini  Stefano Salon 《Marine Ecology》2002,23(S1):122-137

Abstract. This paper describes a new Ocean Acoustic Tomography (OAT) methodology - a passive tomography - presently in an advanced development phase. This technique has been developed for long-term, extensive, remote monitoring of the seawater temperature spatial distribution, which is estimated from the received noise emitted from ships of opportunity. To test the passive tomographic processor under controlled conditions, the components of the naval noise from different kinds of vessels was analysed and realistic naval noise was simulated. The feasibility of the proposed methodology was confirmed by test-runs on semi-synthetic data; its capability to resolve temperature profiles will be better assessed with the use of real acoustic and environmental data collected during the INTIMATE00 experiment performed in October 2000 in the Atlantic Ocean off the Portuguese coast. An analysis of the space and time variability of the Empirical Orthogonal Function (EOF) decomposition of the sound speed (SSP) in the Mediterranean Sea has been carried out to identify areas where acoustic tomography can be successfully applied. Results from simulations in the South Adriatic Sea, which was identified as a region with a high sound speed variability associated with the seasonal cycle and with the main oceanographic processes, are reported.  相似文献   

Intrusive mechanism of the 2002 NE-rift eruption at Mt Etna (Italy) modelled using GPS and gravity data     

Alessandro Bonforte  Daniele Carbone  Filippo Greco  Mimmo Palano 《Geophysical Journal International》2007,169(1):339-347

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Thermal expansion and dehydroxylation of phengite micas     

Mauro Gemmi  Marco Merlini  Alessandro Pavese  Nadia Curetti 《Physics and Chemistry of Minerals》2008,35(7):367-379

Phengite samples (2M ₁ and 3T politypes) and a synthetic end-member muscovite specimen were studied by in situ high-temperature synchrotron radiation X-ray diffraction. The measured volume thermal expansion of 2M ₁ phengite (<α _V> ≈ 36.6 × 10⁻⁶ K⁻¹) was systematically greater than <α _V> of the 3T polytype (≈33.3 × 10⁻⁶ K⁻¹). A positive linear correlation between the average thermal expansion on (001) plane and the mean tetrahedral rotation angle at ambient condition is proposed on the ground of new measurements and literature data. Dehydroxylation processes were observed in 2M ₁, starting at 1,000 K in 3T at 800 and 945 K in synthetic muscovite. Rietveld refinements allowed a determination of structural variations upon heating of phengite samples and their dehydroxylate phases. The phengite structure expands by regularizing the tetrahedral sheet and by reducing the bond length differences between the outer and inner coordination shell of the interlayer site. The dehydroxylate phase derived from 2M ₁ is characterized by fivefold polyhedra in the low temperature form as a consequence of two OH groups reacting to form H₂O + O (residual). The dehydroxylate exhibits an increase of the cation–cation distances along the M–Or–M bonds with respect to low-temperature phengite structures. For the 3T phase, we were unable to achieve completion of dehydroxylation. The refined structural model of the dehydroxylate phase shows two hydroxyl sites, but at a short distance from one another. This result suggests that the dehydroxylation reaction did not proceed to completion. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Earthquake sequences of the last millennium in L’Aquila and surrounding regions (central Italy)     

Alessandro Amato  Maria Grazia Ciaccio 《地学学报》2012,24(1):52-61

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Toward a radiometric ice clock: uranium ages of the Dome C ice core     

Sarah Aciego  Bernard Bourdon  Jakob Schwander  Heinrich Baur  Alessandro Forieri 《Quaternary Science Reviews》2011,30(19-20):2389-2397

Ice sheets and deep ice cores have yielded a wealth of paleoclimate information based on continuous dating methods while independent radiometric ages of ice have remained elusive. Here we demonstrate the application of (²³⁴U/²³⁸U) measurements to dating the EPICA Dome C ice core based on the accumulation of ²³⁴U in the ice matrix from recoil during ²³⁸U decay out of dust bound within the ice. Measured (²³⁴U/²³⁸U) activity ratios within the ice generally increase with depth while the surface areas of the dust grains are relatively constant. Using a newly designed device for measuring surface area for small samples, we were able to estimate reliably the recoil efficiency of nuclides from dust to ice. The resulting calculated radiometric ages range between 80 ka and 870 ka. Measured samples in the upper 3100 m fall on the previously published age-depth profile. Samples in the 3200–3255 m section show a marked change from 723–870 ka to 85 ka indicating homogenization of the deep ice prior to resetting of the (²³⁴U/²³⁸U) age in the basal layers. The mechanism for homogenization is likely enhanced lateral ice flow due to high basal melting and geothermal heat flux.  相似文献   

Effects of the filtering action exerted by piles on the seismic response of RC frame buildings     

Luca de Sanctis  Raffaele Di Laora  Nicola Caterino  Giuseppe Maddaloni  Stefano Aversa  Alessandro Mandolini  Antonio Occhiuzzi 《Bulletin of Earthquake Engineering》2015,13(11):3259-3275

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Seismic performance evaluation of plasterboard partitions via shake table tests   总被引：1，自引：1，他引：0  

Gennaro Magliulo  Crescenzo Petrone  Vittorio Capozzi  Giuseppe Maddaloni  Pauline Lopez  Gaetano Manfredi 《Bulletin of Earthquake Engineering》2014,12(4):1657-1677

The damage of nonstructural components represents the largest contribution to the economic loss caused by an earthquake. Since nonstructural components are not amenable to traditional structural analysis, full-scale experimental testing is crucial to understand their behaviour under earthquake. For this reason, shaking table tests are performed to investigate the seismic behaviour of plasterboard partitions. A steel test frame is properly designed in order to simulate the seismic effects at a generic building storey. The tests are performed shaking the table simultaneously in both horizontal directions. To investigate a wide range of interstorey drift demand and seismic damage, the shakes are performed scaling the accelerograms at eleven different intensity levels. The tested plasterboard partitions from Siniat exhibit a good seismic behaviour, both in their own plane and out of plane, showing limited damage up to 1.1 % interstorey drift ratio. The correlation between the dynamic characteristics of the test setup and the recorded damage is evidenced. Finally, an interesting comparison between the experimental results and the analytical model is also performed.  相似文献   

Optical emission from massive donors in ultraluminous X-ray source binary systems     

Alessandro Patruno  Luca Zampieri 《Monthly notices of the Royal Astronomical Society》2008,386(1):543-552

We present evolutionary tracks of binary systems with high-mass companion stars and stellar-through-intermediate mass black holes (BHs). Using Eggleton's stellar evolution code, we compute the luminosity produced by accretion from the donor during its entire evolution. We compute also the evolution of the optical luminosity and colours of the binary system taking the disc contribution and irradiation effects into account. The calculations presented here can be used to constrain the properties of the donor stars in ultraluminous X-ray sources by comparing their position on the Hertzsprung–Russell or colour–magnitude diagrams with the evolutionary tracks of massive BH binaries. This approach may actually provide interesting clues also on the properties of the binary system itself, including the BH mass. We found that, on the basis of their position on the colour–magnitude diagram, some of the candidate counterparts considered can be ruled out and more stringent constraints can be applied to the donor masses.  相似文献