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1.
Wendy K. Stovall B. F. Houghton A. J. L. Harris D. A. Swanson 《Bulletin of Volcanology》2009,71(3):313-318
Lava lakes are found at basaltic volcanoes on Earth and other planetary bodies. Density-driven crustal foundering leading
to surface renewal occurs repeatedly throughout the life of a lava lake. This process has been observed and described in a
qualitative sense, but due to dangerous conditions, no data has been acquired to evaluate the densities of the units involved.
Kīlauea Iki pit crater in Hawai`i houses a lava lake erupted during a 2 month period in 1959. Part of the surface of the Kīlauea
Iki lake now preserves the frozen record of a final, incomplete, crustal-overturn cycle. We mapped this region and sampled
portions of the foundering crust, as well as overriding and underlying lava, to constrain the density of the units involved
in the overturn process. Overturn is driven by the advance of a flow front of fresh, low-density lava over an older, higher
density surface crust. The advance of the front causes the older crust to break up, founder, and dive downwards into the lake
to expose new, hot, low-density lava. We find density differences of 200 to 740 kg/m3 between the foundering crust and over-riding and under-lying lava respectively. In this case, crustal overturn is driven
by large density differences between the foundering and resurfacing units. These differences lead, inevitably, to frequent
crustal renewal: simple density differences between the surface crust and underlying lake lava make the upper layers of the
lake highly unstable.
Work originally presented at the American Geophysical Union Fall Meeting in San Francisco, California on December 11, 2007. 相似文献
2.
Wendy K. Stovall Bruce F. Houghton Julia E. Hammer Sarah A. Fagents Don A. Swanson 《Bulletin of Volcanology》2012,74(2):441-455
The 1959 summit eruption of Kīlauea volcano produced the highest recorded Hawaiian fountain in Hawai‘i. Quantitative analysis
of closely spaced samples from the final two high-fountaining episodes of the eruption result in a fine-scale textural study
of pyroclasts and provide a record of postfragmentation processes. As clast vesicularity increases, the vesicle number density
decreases and vesicle morphology shifts from small and round to larger and more irregular. The shift in microtexture corresponds
to greater degrees of postfragmentation expansion of clasts with higher vesicularity. We suggest the range of clast morphologies
in the deposit is related to thermal zonation within a Hawaiian fountain where the highest vesicularity clasts traveled in
the center and lowest traveled along the margins. Vesicle number densities are greatest in the highest fountaining episode
and therefore scale with intensity of activity. Major element chemical analyses and fasciculate crystal textures indicate
microlite-rich zones within individual clasts are portions of recycled lava lake material that were incorporated into newly
vesiculating primary melt. 相似文献
3.
Deposits from episode 1 of the 1969–1974 Mauna Ulu eruption of Kīlauea provide an exceptional opportunity to study processes of low intensity Hawaiian fissure fountains. Episode 1 lava flows passed through dense forest that had little impact on flow dynamics; in contrast, the pattern of spatter preservation was strongly influenced by the forest (through the formation of tree molds) and the preexisting topography. A low, near-continuous spatter rampart is present upwind and upslope, on the north side of the fissure. Most of the pyroclastic products, however, fell downwind to the south of the fissure, but little was preserved due to two processes: (1) incorporation of proximal spatter in rheomorphic lava flows 10–20?m from the vents, and (2) the downslope transport of cooler spatter falling on top of these flows beyond 20?m from vent. The lava flow field itself shows a complex history. Initially, discharge from the fissure exceeded the transport capacity of the southern drainage pathways, and lava ponded dynamically to a maximum height of 4?m for 40–120?min, until fountains began to decline. During declining discharge, lava flowed both southward away from the fissure and increasingly back into the vents. There is a clear “lava-shed” or delineation between where lava drained northwards back into the fissure, and where it continued flowing to the south. The 1969 deposits suggest that care is needed when products of less well-documented eruptions are analyzed, as postdepositional transport of spatter may preclude the formation of classic paired (symmetrical) ramparts. 相似文献
4.
Small (1–3 mm), hollow spherules of hexahydrite have been collected falling out of the magmatic gas plume downwind of Kīlauea’s
summit vent. The spherules were observed on eight separate occasions during 2009–2010 when a lake of actively spattering lava
was present ~150–200 m below the rim of the vent. The shells of the spherules have a fine bubbly foam structure less than
0.1 mm thick, composed almost entirely of hexahydrite [MgSO4·6H2O] Small microspherules of lava (<5 μm across) along with mineral and rock fragments from the magmatic plume adhered to the
outside of the hexahydrite spherules. Phase relationships and the particulate matter in the magmatic plume indicate that the
spherules originated as a bubbly solution injected into and mixed with the magmatic plume. The most likely mechanism for production
of hexahydrite spherules is boiling of MgSO4-saturated meteoric water in the walls of the conduit above the surface of the lava lake. Solfataric sulfates may thus be
recycled and reinjected into the plume, creating particulates of sulfate minerals that can be distributed far from their original
source. 相似文献
5.
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
6.
C. C. Heliker M. T. Mangan T. N. Mattox J. P. Kauahikaua R. T. Helz 《Bulletin of Volcanology》1998,59(6):381-393
The Pu'u 'Ō'ō-Kūpaianaha eruption on the east rift zone of Kīlauea began in January 1983. The first 9 years of the eruption
were divided between the Pu'u 'Ō'ō (1983–1986) and Kūpaianaha (1986–1992) vents, each characterized by regular, predictable
patterns of activity that endured for years. In 1990 a series of pauses in the activity disturbed the equilibrium of the eruption,
and in 1991, the output from Kūpaianaha steadily declined and a short-lived fissure eruption broke out between Kūpaianaha
and Pu'u 'Ō'ō. In February 1992 the Kūpaianaha vent died, and, 10 days later, eruptive episode 50 began as a fissure opened
on the uprift flank of the Pu'u 'Ō'ō cone. For the next year, the eruption was marked by instability as more vents opened
on the flank of the cone and the activity was repeatedly interrupted by brief pauses in magma supply to the vents. Episodes
50–53 constructed a lava shield 60 m high and 1.3 km in diameter against the steep slope of the Pu'u 'Ō'ō cone. By 1993 the
shield was pockmarked by collapse pits as vents and lava tubes downcut as much as 29 m through the thick deposit of scoria
and spatter that veneered the cone. As the vents progressively lowered, the level of the Pu'u 'Ō'ō pond also dropped, demonstrating
the hydraulic connection between the two. The downcutting helped to undermine the prominent Pu'u 'Ō'ō cone, which has diminished
in size both by collapse, as a large pit crater formed over the conduit, and by burial of its flanks. Intervals of eruptive
instability, such as that of 1991–1993, accelerate lateral expansion of the subaerial flow field both by producing widely
spaced vents and by promoting surface flow activity as lava tubes collapse and become blocked during pauses.
Received: 1 July 1997 / Accepted: 23 October 1997 相似文献
7.
David A. Clague Jonathan T. Hagstrum Duane E. Champion Melvin H. Beeson 《Bulletin of Volcanology》1999,61(6):363-381
The tube-fed pāhoehoe lava flows covering much of the northeast flank of Kīlauea Volcano are named the 'Ailā'au flows. Their
eruption age, based on published and six new radiocarbon dates, is approximately AD 1445. The flows have distinctive paleomagnetic
directions with steep inclinations (40°–50°) and easterly declinations (0°–10°E). The lava was transported ∼40 km from the
vent to the coast in long, large-diameter lava tubes; the longest tube (Kazumura Cave) reaches from near the summit to within
several kilometers of the coast near Kaloli Point. The estimated volume of the 'Ailā'au flow field is 5.2±0.8 km3, and the eruption that formed it probably lasted for approximately 50 years. Summit overflows from Kīlauea may have been
nearly continuous between approximately AD 1290 and 1470, during which time a series of shields formed at and around the summit.
The 'Ailā'au shield was either the youngest or the next to youngest in this series of shields. Site-mean paleomagnetic directions
for lava flows underlying the 'Ailā'au flows form only six groups. These older pāhoehoe flows range in age from 2750 to <18,000
BP, and the region was inundated by lava flows only three times in the past 5000 years. The known intervals between eruptive
events average ∼1600 years and range from ∼1250 years to >2200 years. Lava flows from most of these summit eruptions also
reached the coast, but none appears as extensive as the 'Ailā'au flow field. The chemistry of the melts erupted during each
of these summit overflow events is remarkably similar, averaging approximately 6.3 wt.% MgO near the coast and 6.8 wt.% MgO
near the summit. The present-day caldera probably formed more recently than the eruption that formed the 'Ailā'au flows (estimated
termination ca. AD 1470). The earliest explosive eruptions that formed the Keanakāko'i Ash, which is stratigraphically above
the 'Ailā'au flows, cannot be older than this age.
Received: 10 October 1998 / Accepted: 12 May 1999 相似文献
8.
During the 2018 eruption of Kīlauea Volcano, Hawai'i, scientists relied heavily on a conceptual model of explosive eruptions triggered when lava-lake levels drop below the water table. Numerical modeling of multiphase groundwater flow and heat transport revealed that, contrary to expectations, liquid water inflow to the drained magma conduit would likely be delayed by months to years, owing to the inability of liquid water to transit a zone of very hot rock. The summit of Kīlauea subsequently experienced an ∼2-month period of consistent repeated collapses, and the crater now extends below the equilibrium position of the water table. Liquid water first emerged into the deepened crater in late July 2019. The timing of first appearance of liquid water (about 14 months postcollapse) and the rate of crater lake filling (currently ∼27 kg/s) were well-predicted by the numerical modeling done in late spring 2018, which forecast liquid inflow after 3 to 24 months at rates of 10 to 100 kg/s. A second-generation groundwater model, reflecting the current crater geometry, forecasts lake filling over the next several years. The successful 2018 to present forecasts with both models are based on unadjusted in situ permeability estimates (1 to 6 × 10−14 m2) and water-table elevations (600 to 800 m) from a nearby research drillhole and geophysical surveys. Important unknowns that affect the reliability of longer-term forecasts include the equilibrium water-table geometry, the rate of evaporation from the hot and growing crater lake (currently ∼29,000 m2 at 70-80 °C), and heterogenous permeability changes caused by the 2018 collapse. 相似文献
9.
Culturally significant oral tradition involving Pele, the Hawaiian volcano deity, and her youngest sister Hi'iaka may involve the two largest volcanic events to have taken place in Hawai'i since human settlement: the roughly 60-year-long ‘Ailā’au eruption during the 15th century and the following development of Kīlauea's caldera. In 1823, Rev. William Ellis and three others became the first Europeans to visit Kīlauea's summit and were told stories about Kīlauea's activity that are consistent with the Pele–Hi'iaka account and extend the oral tradition through the 18th century. Recent geologic studies confirm the essence of the oral traditions and illustrate the potential value of examining other Hawaiian chants and stories for more information about past volcanic activity in Hawai‘i. 相似文献
10.
Mt. Etna, in Sicily (Italy) is well known for frequent effusive and explosive eruptions from both its summit and flanks. South-East
Crater (SE Crater), one of the four summit craters, has been the most active in the last 20 years and often produces episodic
lava fountains over periods lasting from a few weeks to months. The most striking of such eruptive phases was in 2000. Sixty
four lava fountains, separated by quiescent intervals and sometimes associated with lava overflows, occurred that year between
January and June, a time period during which we consider the volcano to have been in episodic eruption. This paper presents
mainly results of petrochemical investigations carried out on both tephra and lavas collected during a number of the lava
fountain episodes in 2000. The new data have been integrated with volcanological and seismic information in order to correlate
the features of the eruptive activity with magma-gas dynamics in the plumbing system of SE Crater. The main findings allow
us to characterise the 2000 episodic eruption in the framework of the recent SE Crater activity. In particular, we infer that
the onset of the 2000 eruption was triggered by the ascent of new, more primitive and volatile-rich magma that progressively
intruded into the SE Crater reservoir, where it mixed with the resident, more evolved magma. Furthermore, we argue that the
2000 SE Crater lava fountains largely resulted from the instability of a foam layer accumulated at the top of the underlying
reservoir and rebuilt prior to each episode, in agreement with the collapsing foam model for lava fountains. 相似文献
11.
Karen Guihou Julien Marmain Yann Ourmières Anne Molcard Bruno Zakardjian Philippe Forget 《Ocean Dynamics》2013,63(7):793-808
The Northern current is the main circulation feature of the North-Western Mediterranean Sea. While the large-scale to mesoscale variability of the northern current (NC) is well known and widely documented for the Ligurian region, off Nice or along the Gulf of Lions shelf, few is known about the current instabilities and its associated mesoscale dynamics in the intermediate area, off Toulon. Here, we took advantage of an oceanographic cruise of opportunity, the start of a HF radar monitoring programme in the Toulon area and the availability of regular satellite sea surface temperature and chlorophyll a data, to evaluate the realism of a NEMO-based regional high-resolution model and the added value brought by HF radar. The combined analysis of a 1/64° configuration, named GLAZUR64, and of all data sets revealed the occurrence of an anticyclonic coastal trapped eddy, generated inside a NC meander and passing the Toulon area during the field campaign. We show that this anticyclonic eddy is advected downstream along the French Riviera up to the study region and disturbs the Northern current flow. This study aims to show the importance of combining observations and modelling when dealing with mesoscale processes, as well as the importance of high-resolution modelling. 相似文献
12.
13.
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
14.
M. Aulinas L. Civetta M. A. Di Vito G. Orsi D. Gimeno J. L. Férnandez-Turiel 《Bulletin of Volcanology》2008,70(7):825-840
The Pomici di Mercato (PdM, 8,010 ± 40 a), also known in the literature as Pomici Gemelle or Pomici di Ottaviano, is one of
the oldest Plinian eruptions of Somma-Vesuvius. This eruption occurred after the longest (7 ka) quiescence period of the volcano
and was followed by more than 4 ka of repose. The erupted magma is phonolitic in composition. All the products have very low
phenocrysts content (less than 3%) and show evidence of mineralogical disequilibria. They contain K-feldspar ± clinopyroxene
(salite and diopside) ± plagioclase ± garnet ± biotite ± amphibole ± apatite ± Fe-Ti oxides. Pumice fragments collected at
different stratigraphic heights are slightly less evolved and more enriched in radiogenic Sr composition upsection. The glass
composition is fairly homogeneous in single pumice fragment and among pumice fragments from different layers. Glass separated
from pumice fragments collected at different stratigraphic heights is homogeneous in the Sr-isotope composition (around a
value of 0.70717). Glass is in isotopic equilibrium with salite throughout the entire sequence and with diopside at the base
of the sequence. Diopside becomes more radiogenic upsection, reaching a value of 0.707458 ± 7, whereas feldspar is consistently
slightly less radiogenic than glass. Nd-isotope composition is fairly uniform (ca. 0.51247) through the whole sequence. The
isotopic disequilibria among glass, feldspar and diopside, together with the homogeneous isotopic composition of pumice glass
in equilibrium with salite, and the mineralogical disequilibria between plagioclase and K-feldspar, imply that most of the
diopside and plagioclase crystals are xenocrysts incorporated into the phonolitic magma during residence in a magma chamber
and/or during ascent towards the surface. The PdM Tephra are compositionally and isotopically similar to the phonolitic, first-erupted
products of the subsequent Pomici di Avellino Plinian eruption. On the basis of this similarity, we suggest that the magma
feeding both eruptions resulted from the tapping of a unique magma chamber. Prior to the PdM eruption, this chamber was formed
by a large and homogeneous phonolitic magma body. After the PdM eruption, as a consequence of new arrivals of more radiogenic
in Sr, less-differentiated magma batches, the magma chamber progressively developed a slightly stratified phonolitic uppermost
portion, capping a tephriphonolitic layer, both emitted during the subsequent Pomici di Avellino eruption. 相似文献
15.
16.
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
17.
The seismicity that accompanied the Tolbachik Fissure Eruption was recorded by additional seismic stations that were installed in the southern Klyuchevskoi Volcanic Cluster area in January to October 2013. We used broadband (0.033–50 Hz) three-component digital Guralp CMG-6TD seismometers. This temporary network provided seismicity data at a lower energy level than can be done using the regional seismograph network of Kamchatka. The processing of the resulting digital records supplied data for compiling a catalog of over 700 M L = 0–3.5 (K S = 1.5–8.5) earthquakes, which is an order of magnitude greater than the number of events located by the regional network for the same period of time. The seismicity in the area of Ploskii Tolbachik Volcano was found to concentrate mostly in spatially isolated areas during the eruption. The main isolated clusters of earthquakes were identified both in the eruption area itself and along the periphery of Ploskii Tolbachik Volcano, in the area of the Zimina volcanic massif, and in the Tolud epicenter zone; the eruption zone was not dominant in the seismicity. The region of a shallow seismicity increase beneath Ploskii Tolbachik before the eruption was not found to exhibit any increased activity during the time the temporary seismograph network was operated, which means that a seismicity inversion took place at the beginning of the eruption. We discuss the question of what the earthquake-generating features are that we have identified. 相似文献
18.
Daniela Mele Roberto Sulpizio Pierfrancesco Dellino Luigi La Volpe 《Bulletin of Volcanology》2011,73(3):257-278
New volcanological studies allow reconstruction of the eruption dynamics of the Pomici di Mercato eruption (ca 8,900 cal.
yr B.P.) of Somma-Vesuvius. Three main Eruptive Phases are distinguished based on two distinct erosion surfaces that interrupt
stratigraphic continuity of the deposits, indicating that time breaks occurred during the eruption. Absence of reworked volcaniclastic
deposits on top of the erosion surfaces suggests that quiescent periods between eruptive phases were short perhaps lasting
only days to weeks. Each of the Eruptive Phases was characterised by deposition of alternating fall and pyroclastic density
current (PDC) deposits. The fallout deposits blanketed a wide area toward the east, while the more restricted PDC deposits
inundated the volcano slopes. Eruptive dynamics were driven by brittle magmatic fragmentation of a phonolitic magma, which,
because of its mechanical fragility, produced a significant amount of fine ash. External water did not significantly contribute
either to fragmentation dynamics or to mechanical energy release during the eruption. Column heights were between 18 and 22 km,
corresponding to mass discharge rates between 1.4 and 6 × 107 kg s−1. The estimated on land volume of fall deposits ranges from a minimum of 2.3 km3 to a maximum of 7.4 km3. Calculation of physical parameters of the dilute pyroclastic density currents indicates speeds of a few tens of m s−1 and densities of a few kg m−3 (average of the lowermost 10 m of the currents), resulting in dynamic pressures lower than 3 kPa. These data suggest that
the potential impact of pyroclastic density currents of the Pomici di Mercato eruption was smaller than those of other Plinian
and sub-Plinian eruptions of Somma-Vesuvius, especially those of 1631 AD and 472 AD (4–14 kPa), which represent reference
values for the Vesuvian emergency plan. The pulsating and long-lasting behaviour of the Pomici di Mercato eruption is unique
in the history of large explosive eruptions of Somma-Vesuvius. We suggest an eruptive scheme in which discrete magma batches
rose from the magma chamber through a network of fractures. The injection and rise of the different magma batches was controlled
by the interplay between magma chamber overpressure and local stress. The intermittent discharge of magma during a large explosive
eruption is unusual for Somma-Vesuvius, as well as for other volcanoes worldwide, and yields new insights for improving our
knowledge of the dynamics of explosive eruptions. 相似文献
19.
Gas pistoning is a type of eruptive behavior described first at K??lauea volcano and characterized by the (commonly) cyclic rise and fall of the lava surface within a volcanic vent or lava lake. Though recognized for decades, its cause continues to be debated, and determining why and when it occurs has important implications for understanding vesiculation and outgassing processes at basaltic volcanoes. Here, we describe gas piston activity that occurred at the Pu??u ???????? cone, in K??lauea??s east rift zone, during June 2006. Direct, detailed measurements of lava level, made from time-lapse camera images captured at close range, show that the gas pistons during the study period lasted from 2 to 60?min, had volumes ranging from 14 to 104?m3, displayed a slowing rise rate of the lava surface, and had an average gas release duration of 49?s. Our data are inconsistent with gas pistoning models that invoke gas slug rise or a dynamic pressure balance but are compatible with models which appeal to gas accumulation and loss near the top of the lava column, possibly through the generation and collapse of a foam layer. 相似文献
20.
Chiara M. Petrone Eleonora Braschi Lorella Francalanci 《Journal of Volcanology and Geothermal Research》2009
The Secche di Lazzaro (SDL) phreatomagmatic activity, with the associated Neostromboli sector collapse, represents the most powerful activity of the last 6 ky at Stromboli. As revealed by its present-day activity, Stromboli is one of the most eruptive volcanoes in Italy, and flank instability, along its NW flank, is a common process. Volcano instability is often dramatised by explosive eruptions, thus it is of crucial importance to understand the linking between volcano collapse and the plumbing system itself. The possible role of pre-eruptive magmatic processes as triggers of explosive eruptions can be mainly preserved by minerals and revealed by petrochemical studies. We studied the juvenile components (scoria and pumice) of the pyroclastic deposits from the SDL phreatomagmatic activity with the aim to understand the eruption–collapse link. 相似文献