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The May, 2008, Chaitén (southern Chile) eruption was characterized by several explosive events, each associated with plumes which reached up to about 19?km above sea level on May 6. A study of the textural and physical features of the juvenile clasts erupted during the climactic phase of the 2008 eruption of Chaitén is presented. Pumice clasts show unimodal density distribution (main mode at 600?kg/m3), average vesicularity of about 69?%, a glassy groundmass with no microcrystals, and vesicles with dimension between ～1?μm and ～2?mm. They also show a unimodal vesicle size distribution with most frequent vesicle size in the range 0.05–0.08?mm and an estimated vesicle number density of 1.3?±?0.5?×?105?mm?3 related to a rapid nucleation event produced during the late phases of magma rise. This is confirmed by the absence of microcrystals that could otherwise have delayed vesicle formation and allowed the magma to maintain a low viscosity and a supersaturation in volatiles. Vesiculation and fragmentation were triggered by a sudden decompression of the melt associated with the opening of the volcanic conduit (～10?MPa?s?1). 相似文献
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The tephra fallout from the 12–15 August 1991 explosive eruption of Hudson volcano (Cordillera de los Andes, 45°54 S-72°58 W; Chile) was dispersed on a narrow, elongated ESE sector of Patagonia, covering an area (on land) of more than 100 000 km2. The elongated shape of the deposit, together with the relatively coarse mean and median values of the particles at a considerable distance from the vent, were the result of strong winds blowing to the southeast during the eruption. The thickness of the fall deposit decreases up to 250 km ESE from Hudson volcano, where it begins to thicken again. Secondary maxima are well developed at approximately 500 km from the vent. Secondary maxima, together with grainsize bimodality in individual layers and in the bulk deposit suggest that particle aggregation played an important role in tephra sedimentation. The fallout deposit is well stratified, with alternating fine-grained and coarsegrained layers, which is probably a result of strong eruptive pulses followed by relatively calm periods and/or changes in the eruptive style from plinian to phreatoplinian. The tephra is mostly composed of juvenile material: the coarse mode (mostly pumice) shifts to finer sizes with distance from the volcano; the fine mode (mostly glass shards) is always about 5/6 phi. Glass shards and pumice are mostly light gray to colorless. However, considerable amounts of dark, poorly vesiculated, blocky shards, suggest a hydromagmatic component in the eruption. A land-based tephra volume of 4.35 km3 was estimated, and a total volume of 7.6 km3 arose from an extrapolation, which took into account the probable volume sedimented in the sea. Bulk density ranges from 0.9 to 1.10 gr/cm3 (beyond 110 km from the vent). Rather uniform density values measured in crushed samples (2.45–2.50 gr/cm3 at all distances from the vent) reveal a relatively homogeneous composition. Mean and median sizes decrease rapidly up to 270 km from the vent; beyond that point they are more or less constant, whereas the maximum size (1 phi) shows a steady decrease up to 550 km. A concomitant improvement in sorting is observed. This is attributed to sorting due to wind transport combined with particle aggregation at different times and distances from the vent. The Hudson tephra fallout shares some strikingly similar features with the Mount St. Helens (18 May 1980) and Quizapu (1932) eruptions. 相似文献
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Servando De la Cruz-Reyna Izumi Yokoyama Alicia Martínez-Bringas Esteban Ramos 《Bulletin of Volcanology》2008,70(6):753-767
Popocatépetl Volcano is located in the central Mexican Volcanic Belt, within a densely populated region inhabited by over
20 million people. The eruptive history of this volcano indicates that it is capable of producing a wide range of eruptions,
including Plinian events. After nearly 70 years of quiescence, Popocatépetl reawakened in December 21, 1994. The eruptive
activity has continued up until the date of this submission and has been characterized by a succession of lava dome growth-and-destruction
episodes, similar to events that have apparently been typical for Popocatépetl since the fourteenth century. In this regime,
the episodes of effusive and moderately explosive activity alternate with long periods of almost total quiescence. In this
paper we analyze five years of volcano-tectonic seismicity preceding the initial eruption of the current episode. The evolution
of the V-T seismicity shows four distinct stages, which we interpret in terms of the internal processes which precede an eruption
after a long period of quiescence. The thermal effects of a magma intrusion at depth, the fracturing related to the slow development
of magma-related fluid pathways, the concentration of stress causing a protracted acceleration of this process, and a final
relaxation or redistribution of the stress shortly before the initial eruption are reflected in the rates of V-T seismic energy
release. A hindsight analysis of this activity shows that the acceleration of the seismicity in the third stage asymptotically
forecast the time of the eruption. The total seismic energy release needed to produce an eruption after a long period of quiescence
is related to the volume of rock that must be fractured so imposing a characteristic threshold limit for polygenetic volcanoes,
limit that was reached by Popocatépetl before the eruption. 相似文献
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Understanding explosive volcanic eruptions, especially phreatomagmatic eruptions, their intensities and energy budgets is of major importance when it comes to risk and hazard studies. With only a few historic occurrences of phreatomagmatic activity, a large amount of our understanding comes from the study of pre-historic volcanic centres, which causes issues when it comes to preservation and vegetation. In this research, we show that using 3D geometrical modelling it is possible to obtain volume estimates for different deposits of a pre-historic, complex, monogenetic centre, the Mt. Gambier Volcanic Complex, south-eastern Australia. Using these volumes, we further explore the energy budgets and the magnitude of this eruption (VEI 4), including dispersal patterns (eruption columns varying between 5 and 10 km, dispersed towards north-east to south), to further our understanding of intraplate, monogenetic eruptions involving phreatomagmatic activity. We also compare which thermodynamic model fits best in the creation of the maar crater of Mt. Gambier: the major-explosion-dominated model or the incremental growth model. In this case, the formation of most of the craters can best be explained by the latter model. 相似文献
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Eruption dynamics of Hawaiian-style fountains: the case study of episode 1 of the Kīlauea Iki 1959 eruption 总被引：1，自引：1，他引：0
Wendy K. Stovall B. F. Houghton H. Gonnermann S. A. Fagents D. A. Swanson 《Bulletin of Volcanology》2011,73(5):511-529
Hawaiian eruptions are characterized by fountains of gas and ejecta, sustained for hours to days that reach tens to hundreds
of meters in height. Quantitative analysis of the pyroclastic products from the 1959 eruption of Kīlauea Iki, Kīlauea volcano,
Hawai‘i, provides insights into the processes occurring during typical Hawaiian fountaining activity. This short-lived but
powerful eruption contained 17 fountaining episodes and produced a cone and tephra blanket as well as a lava lake that interacted
with the vent and fountain during all but the first episode of the eruption, the focus of this paper. Microtextural analysis
of Hawaiian fountaining products from this opening episode is used to infer vesiculation processes within the fountain and
shallow conduit. Vesicle number densities for all clasts are high (106–107 cm−3). Post-fragmentation expansion of bubbles within the thermally-insulated fountain overprints the pre-fragmentation bubble
populations, leading to a reduction in vesicle number density and increase in mean vesicle size. However, early quenched rims
of some clasts, with vesicle number densities approaching 107 cm−3, are probably a valid approximation to magma conditions near fragmentation. The extent of clast evolution from low vesicle-to-melt
ratio and corresponding high vesicle number density to higher vesicle-to-melt ratio and lower vesicle-number density corresponds
to the length of residence time within the fountain. 相似文献
8.
The April 16, 1991, eruption of Volcán de Colima represents a classical example of partial dome collapse with the generation of progressively longer-runout, Merapi-type pyroclastic flows that traveled up to 4 km along the El Cordoban gullies (East, Central and West). The flows filled the gullies with block-and-ash flow deposits up to 10 m thick, of which, after 7 years of erosion, only remnants remained in the El Cordoban West and East gullies. The El Cordoban Central gully, however, provided a well-preserved and incised longitudinal section of the 1991 deposits. The deposits were emplaced as proximal and distal facies, separated by a change in slope angle from >30° to <20°. The proximal facies consists of massive, clast-supported flow units (up to 1 m thick) with andesite blocks locally supported by a matrix of coarse ash and devoid of segregation structures or grading. The distal facies consists of a massive, matrix-supported deposit up to 8 m thick, which contains dispersed andesite blocks in a fine ash matrix. In the distal facies, a train of blocks marks flow-unit upper boundaries and, although sorting is poor, some grading is present. Thin, finely stratified, or dune-bedded layers of fine ash material are locally present above or below units of both facies. Sedimentologic parameters show that the size or fraction of large pyroclasts (larger than –1 ) decreases from proximal to distal facies, as the percentage of matrix (0 to 4 ) increases, especially immediately beyond the break in slope. We propose that the propagation of the Colima pyroclastic flows is critically dependent on local slope angle, the presence of erodible slope debris, and the decrease in grain size with distance from the vent. The progressive fining is probably caused by some combination of erosion, clast breakup and deposition of larger pyroclasts, and is itself influenced by the slope angle. In the proximal region, the flows moved as granular avalanches, in which interacting grains ground each other and erosion occurred to produce an overriding dilute ash cloud. The maximum runout distance of the avalanches was controlled by the angle of repose of the material, and the volume and grain size of source and eroded material. Because the slope angle is close to the repose angle for this debris, granular avalanches were not able to propagate far beyond the change in slope. If, however, an avalanche had enough mass in finer grain size fractions, at least part of the flow continued beyond the break in slope and across the volcano apron, propagating in a turbulent state and depositing surge layers, or in an otherwise settling-modified state and depositing block-and-ash flow layers.Editorial responsibility: T Druitt 相似文献
9.
Observations of the summit eruption of Klyuchevskoi volcano in the period from February 15, 2007 to July 9, 2007 are considered. This typical (for this volcano) summit eruption was explosive-effusive in character. The ejectamenta volume is estimated at 0.025 km3. Calculation of active phases of the volcano was carried out in accordance with V.A. Shirokov’s technique. The identified active phases agree well with the eruptive periods. The 2007 summit eruption corresponds to an active phase (May 2006 to May 2009) favorable for the volcano’s eruption. Geodetic observations carried out since 1979 along a radial profile have revealed uplifts and subsidences of the northeastern slope of the volcano. The maximum displacement of 23 cm was recorded in 2007 on the site closest to the volcano crater at a distance of 11 km from the summit crater center. In the course of two previous summit eruptions (2003–2004 and 2005) insignificant uplifts and subsidences of the slope were also noted, although the general ascent of the slope remained. This indicated possible repeated eruptions in the nearest future. Changes in the seismicity before, during and after the eruption are also discussed. 相似文献
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A. I. Skorokhod N. F. Elansky A. N. Safronov I. D. Eremina N. V. Pankratova N. E. Chubarova 《Journal of Volcanology and Seismology》2016,10(4):263-274
This paper reports a study of the April 2010 Eyjafjallajökull eruption on the atmosphere composition in Moscow. Concentrations of some gases, including sulfur dioxide, were measured at a station operated by Moscow University and the Institute of Atmospheric Physics. The impact of this eruption was felt, not only in the composition of the gaseous medium, but also in that of atmospheric precipitation as sampled and analyzed at the Meteorological Observatory of Moscow University. The NOAA hysplit model was used to carry out forward and backward trajectory analyses. It is shown that the descent of air masses during an anticyclone is a necessary condition for reliable recording of volcanic admixtures by ground-based stations. 相似文献
12.
The impacts of pyroclastic surges on buildings at the eruption of the Soufrière Hills volcano, Montserrat 总被引：1，自引：0，他引：1
Peter J. Baxter Robin Boyle Paul Cole Augusto Neri Robin Spence Giulio Zuccaro 《Bulletin of Volcanology》2005,67(4):292-313
We investigated the impacts on buildings of three pyroclastic surges that struck three separate villages on 25 June, 21 September and 26 December, 1997, during the course of the andesitic dome building eruption of the Soufrière Hills Volcano, Montserrat, which began on 18 July, 1995. A detailed analysis of the building damage of the 26 December event was used to compare the findings on the flow and behaviour of dilute pyroclastic density currents (PDCs) with the classical reports of PDCs from historical eruptions of similar size. The main characteristics of the PDC, as inferred from the building damage, were the lateral loading and directionality of the current; the impacts corresponded to the dynamic pressure of the PDC, with a relatively slow rate of rise and without the peak overpressure or a shock front associated with explosive blast; and the entrainment of missiles and ground materials which greatly added to the destructiveness of the PDC. The high temperature of the ash, causing the rapid ignition of furniture and other combustibles, was a major cause of damage even where the dynamic pressure was low at the periphery of the current. The vulnerability of buildings lay in the openings, mainly windows, which allowed the current to enter the building envelope, and in the flammable contents, as well as the lack of resistance to the intense heat and dynamic pressure of some types of vernacular building construction, such as wooden chattel houses, rubble masonry walls and galvanised steel-sheet roofs. Marked variability in the level of damage due to dynamic pressure (in a range 1–5 kPa, or more) was evident throughout most of the impact area, except for the zone of total loss, and this was attributable to the effects of topography and sheltering, and projectiles, and probably localised variations in current velocity and density. A marked velocity gradient existed from the outer part to the central axis of the PDC, where buildings and vegetation were razed to the ground. The gradient correlated with the impacts due to lateral loading and heat transfer, as well as the size of the projectiles, whilst the temperature of the ash in the undiluted PDC was probably uniform across the impact area. The main hazard characteristics of the PDCs were very consistent with those described by other authors in the classic eruptions of Pelée (1902), Lamington (1951) and St Helens (1980), despite differences in the eruptive styles and scales. We devised for the first time a building damage scale for dynamic pressure which can be used in research and in future volcanic emergencies for modelling PDCs and making informed judgements on their potential impacts. Editorial responsibility: T. Druitt 相似文献
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After decades of repose, Puyehue-Cordón Caulle Volcano (Chile) erupted in June 2011 following a month of continuously increasing seismic activity. The eruption dispersed a large volume of rhyolitic tephra over a wide area and was characterized by complex dynamics. During the initial climactic phase of the eruption (24–30 h on 4–5 June), 11–14-km-high plumes dispersed most of the erupted tephra eastward towards Argentina, reaching as far as the Atlantic Ocean. This first eruptive phase was followed by activity of lower intensity, leading to the development of a complex stratigraphic sequence, mainly due to rapid shifts in wind direction and eruptive style. The resulting tephra deposits consist of 13 main layers grouped into four units. Each layer was characterized based on its dispersal direction, sedimentological features, and on the main characteristics of the juvenile fraction (texture, density, petrography, chemistry). The lowest part of the eruptive sequence (Unit I), corresponding to the tephra emitted between 4 and 5 June, is composed of alternating lapilli layers with a total estimated volume of ca. 0.75 km3; these layers record the highest intensity phase, during which a bent-over plume dispersed tephra towards the southeast-east, with negligible up-wind sedimentation. Products emitted during 5–6 June (Unit II) signaled an abrupt shift in wind direction towards the north, leading to the deposition of a coarse ash deposit in the northern sector (ca. 0.21 km3 in volume), followed by a resumption of easterly directed winds. A third phase (Unit III) began on 7 June and resulted in tephra deposits in the eastern sector and ballistic bombs around the vent area. A final phase (Unit IV) started after 15 June and was characterized by the emission of fine-grained white tephra from ash-charged plumes during low-level activity and the extrusion of a viscous lava flow. Timing and duration of the first eruptive phases were constrained based on comparison of the dispersal of the main tephra layers with satellite images, showing that most of the tephra was emitted during the first 72 h of the event. The analyzed juvenile material tightly clusters within the rhyolitic field, with negligible chemical variations through the eruptive sequence. Textural observations reveal that changes in eruption intensity (and consequently in magma ascent velocity within the conduit) and complex interactions between gas-rich and gas-depleted magma portions during ascent resulted in vesicular clasts with variable degrees of shear localization, and possibly in the large heterogeneity of the juvenile material. 相似文献
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Flank instability and collapse are observed at many volcanoes. Among these, Mt. Etna is characterized by the spreading of its eastern and southern flanks. The eastern spreading area is bordered to the north by the E–W-trending Pernicana Fault System (PFS). During the 2002–2003 Etna eruption, ground fracturing along the PFS migrated eastward from the NE Rift, to as far as the 18 km distant coastline. The deformation consisted of dextral en-echelon segments, with sinistral and normal kinematics. Both of these components of displacement were one order of magnitude larger (~1 m) in the western, previously known, portion of the PFS with respect to the newly surveyed (~9 km long) eastern section (~0.1 m). This eastern section is located along a pre-existing, but previously unknown, fault, where displaced man-made structures give overall slip rates (1–1.9 cm/year), only slightly lower than those calculated for the western portion (1.4–2.3 cm/year). After an initial rapid motion during the first days of the 2002–2003 eruption, movement of the western portion of the PFS decreased dramatically, while parts of the eastern portion continued to move. These data suggest a model of spreading of the eastern flank of Etna along the PFS, characterized by eruptions along the NE Rift, instantaneous, short-lived, meter-scale displacements along the western PFS and more long-lived centimeter-scale displacements along the eastern PFS. The surface deformation then migrated southwards, reactivating, one after the other, the NNW–SSE-trending Timpe and Trecastagni faults, with displacements of ~0.1 and ~0.04 m, respectively. These structures, along with the PFS, mark the boundaries of two adjacent blocks, moving at different times and rates. The new extent of the PFS and previous activity over its full length indicate that the sliding eastern flank extends well below the Ionian Sea. The clustering of seismic activity above 4 km b.s.l. during the eruption suggests a deep décollement for the moving mass. The collected data thus suggests a significant movement (volume >1,100 km3) of the eastern flank of Etna, both on-shore and off-shore.Editorial responsibility: R. Cioni 相似文献
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Marie-Christine Gerbe Alain Gourgaud Olgeir Sigmarsson Russell S Harmon Jean-Louis Joron Ariel Provost 《Bulletin of Volcanology》1992,54(4):284-298
Pyroclastic deposits from the 1982–1983 eruption of Galunggung volcano (Java, Indonesia) reflect preeruptive magmatic evolution which is of interest because of: (1) its duration of nine months, compared to a few hours or days for most historical eruptions; (2) the diversity of eruptive styles, from ash and scoria flows to phreatomagmatic explosions, and to the strombolian activity that marked the end of the eruption; and (3) the progressive variation in chemical composition with time, from andesite (58 wt.% SiO2) to high-Mg basalt (47 wt.% SiO2). The 1982–1983 Galunggung basalts are rather primitive: 10 to 12 wt% MgO, 180 to 200 ppm Ni and 550 to 700 ppm Cr. Despite the presence of about 40% phenocrysts, they may represent the most primitive basalts recognized in western Java. Basalts contain phenocrysts of olivine (Fo90-80), diopside-salite, and plagioclase (An95-75). Andesites contain plagioclase (An80–60), augite, hypersthene (En67-64), and titanomagnetite. The distribution of mineral compositions in each petrographic type is nearly unimodal, although scarce plagioclase and olivine xenocrysts have been observed. Abundance of gabbroic cumulates associated with the pyroclastic flows and evolution of mineral compositions from high-Mg basalts to andesites support crystal fractionation as the main differentiation mechanism, although magma mixing of basaltic andesite and andesite cannot be excluded. Major and trace element trends, which display rough decreases of MgO, CaO, Ni, Cr with increasing degree of differentiation and also linear positive correlations of hygromagmaphile elements, are compatible with both processes. However, some discrepancies are observed between major and trace element modelling, which may be explained to some extent by the influence of in situ crystallization and/or magma mixing. The constancy of 143Nd/144Nd (0.51286±3), 230Th/232Th (0.65±0.02), Th/U (4.08±0.07) ratios, and to a lesser extent 18O values (+5.8 to +6.4 % SMOW) and 87Sr/86Sr ratios (0.70440 to 0.70468) is compatible with a magmatic evolution through fractional crystallization without significant crustal contamination. Nevertheless low-18O and high 87Sr/86Sr values in basaltic andesites may be due to the introduction of meteoric fluids into the Galunggung magma. 相似文献
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Event-stratigraphy of a caldera-forming ignimbrite eruption on Tenerife: the 273 ka Poris Formation 总被引：1，自引：1，他引：0
The 273 ka Poris Formation in the Bandas del Sur Group records a complex, compositionally zoned explosive eruption at Las Cañadas caldera on Tenerife, Canary Islands. The eruption produced widespread pyroclastic density currents that devastated much of the SE of Tenerife, and deposited one of the most extensive ignimbrite sheets on the island. The sheet reaches ~ 40-m thick, and includes Plinian pumice fall layers, massive and diffuse-stratified pumiceous ignimbrite, widespread lithic breccias, and co-ignimbrite ashfall deposits. Several facies are fines-rich, and contain ash pellets and accretionary lapilli. Eight brief eruptive phases are represented within its lithostratigraphy. Phase 1 comprised a fluctuating Plinian eruption, in which column height increased and then stabilized with time and dispersed tephra over much of the southeastern part of the island. Phase 2 emplaced three geographically restricted ignimbrite flow-units and associated extensive thin co-ignimbrite ashfall layers, which contain abundant accretionary lapilli from moist co-ignimbrite ash plumes. A brief Plinian phase (Phase 3), again dispersing pumice lapilli over southeastern Tenerife, marked the onset of a large sustained pyroclastic density current (Phase 4), which then waxed (Phase 5), covering increasingly larger areas of the island, as vents widened and/or migrated along opening caldera faults. The climax of the Poris eruption (Phase 6) was marked by widespread emplacement of coarse lithic breccias, thought to record caldera subsidence. This is inferred to have disturbed the magma chamber, causing mingling and eruption of tephriphonolite magma, and it changed the proximal topography diverting the pyroclastic density current(s) down the Güimar valley (Phase 7). Phase 8 involved post-eruption erosion and sedimentary reworking, accompanied by minor down-slope sliding of ignimbrite. This was followed by slope stabilization and pedogenesis. The fines-rich lithofacies with abundant ash pellets and accretionary lapilli record agglomeration of ash in moist ash plumes. They resemble phreatomagmatic deposits, but a phreatomagmatic origin is difficult to establish because shards are of bubble-wall type, and the moisture may have arisen by condensation within ascending thermal co-ignimbrite ash plumes that contained atmospheric moisture enhanced by that derived from the evaporation of seawater where the hot pyroclastic currents crossed the coast. Ash pellets formed in co-ignimbrite ash-clouds and then fell through turbulent pyroclastic density currents where they accreted rims and evolved into accretionary lapilli.Editorial Responsibility: J. Stix 相似文献
19.
The 1998 eruption of Volcan Cerro Azul, Isla Isabela, Galápagos Islands, was observed in near real-time by the Geostationary
Operational Environmental Satellite-8 (GOES-8) weather satellite. Due to the remote location of the eruption site, 3.9-μm
radiance values derived from GOES band 2 provide the best timing of the start and termination of the eruption, which occurred
on 15 Sept. and 21 Oct., respectively. Throughout the 36-day long eruption, a total of 1335 thermal infrared images were collected,
of which 851 were cloud-free and permitted the thermal anomaly to be detected. A detailed chronology including 77 separate
events was assembled from the GOES data and field observations. Numerous attributes of the eruption were observed from the
GOES data, including the sizes and dispersal of seven eruption plumes and the occurrence and timing of intra-caldera effusive
activity. The growth of a lava flow on the SE flank, the formation of smoke and volcanic haze from the flank vent, and burning
of vegetation caused by lava flows entering vegetated areas were monitored both on the ground and with the satellite data.
In most cases GOES images were processed as they were received every 30 min and were then distributed over the Internet within
minutes of reception. These data provided timely high-temporal information to field parties as well as enabled the documentation
of the eruption. The GOES observations of Cerro Azul serve as a further example of the way in which the remote sensing community
and field volcanologists can collaborate during future eruptions, and permit the temporal and spatial resolution requirements
for future satellites systems to be better defined.
Received: 27 April 1999 / Accepted: 21 February 2000 相似文献
20.
Rosa Anna Corsaro Lucia Civetta Valeria Di Renzo Lucia Miraglia 《Bulletin of Volcanology》2009,71(7):781-793
Following the 2001 and 2002–2003 flank eruptions, activity resumed at Mt. Etna on 7 September 2004 and lasted for about 6 months.
This paper presents new petrographic, major and trace element, and Sr–Nd isotope data from sequential samples collected during
the entire 2004–2005 eruption. The progressive change of lava composition allowed defining three phases that correspond to
different processes controlling magma dynamics inside the central volcano conduits. The compositional variability of products
erupted up to 24 September is well reproduced by a fractional crystallization model that involves magma already stored at
shallow depth since the 2002–2003 eruption. The progressive mixing of this magma with a distinct new one rising within the
central conduits is clearly revealed by the composition of the products erupted from 24 September to 15 October. After 15
October, the contribution from the new magma gradually becomes predominant, and the efficiency of the mixing process ensures
the emission of homogeneous products up to the end of the eruption. Our results give insights into the complex conditions
of magma storage and evolution in the shallow plumbing system of Mt. Etna during a flank eruption. Furthermore, they confirm
that the 2004–2005 activity at Etna was triggered by regional movements of the eastern flank of the volcano. They caused the
opening of a complex fracture zone extending ESE which drained a magma stored at shallow depth since the 2002–2003 eruption.
This process favored the ascent of a different magma in the central conduits, which began to be erupted on 24 September without
any significant change in eruptive style, deformation, and seismicity until the end of eruption. 相似文献