novel retrieval of volcanic so2 abundance from ultraviolet spectra projects i firb miur simulazione dei flussi lavici con gli automi cellulari n rbau01rmz4 002 ii sviluppo di sistemi di monitoraggio funded by dipartimento di protezione civile della regione sicilia ingv istituto nazionale di geofisica e vulcanologia sezione di catania italy iii eu funded sixth framework programme project 18354 novac iv leverhulme trust fellowship

ash erupted during normal activity at stromboli aeolian islands italy raises questions on how the feeding system works ash fallout collected during 4 days of sampling at stromboli confirms that a crystal rich hp degassed magma erupts during the strombolian explosions that are characteristic of the normal activity of this volcano we identified 3 different types of juvenile ash fragments fluidal spongy and dense which formed through different mechanisms of fragmentation of the low viscosity physically heterogeneous in terms of the size and spatial distribution of bubbles shoshonitic magma a small amount less than 3 vol of volatile rich magma with low porphyricity lp erupted as highly vesicular ash fragments has been collected together with the hp magma during normal strombolian explosions laboratory experiments and the morphological textural and compositional investigations of ash fragments reveal that the lp ash is fresh and not recycled from the last paroxysm 15 march 2007 we suggest that small droplets of lp magma are dragged to the surface by the time variable but persistent supply of deep derived co2 rich gas bubbles this coupled ascent of bubbles and lp melts is transient and does not perturb the dynamics of the hp magma within the shallow reservoir this finding provides a new perspective on how the stromboli volcano works and has important implications for monitoring strategies

source mechanisms of explosions at stromboli volcano italy determined from moment tensor inversions of very long period data 1 seismic data recorded in the 2 30 s band at stromboli volcano italy are analyzed to quantify the source mechanisms of strombolian explosions during september 1997 to determine the source centroid location and source mechanism we minimize the residual error between data and synthetics calculated by the finite difference method for a point source embedded in a homogeneous elastic medium that takes topography into account two source centroids are identified each representative of the distinct event types associated with explosive eruptions from two different vents the observed waveforms are well reproduced by our inversion and the two source centroids that best fit the data are offset 220 and 260 m beneath and 160 m northwest of the active vents the source mechanisms include both moment tensor and single force components the principal axes of the moment tensor have amplitude ratios 1 1 2 which can be interpreted as representative of a crack if one assumes the rock matrix at the source to have a poisson ratio n 1 3 a value appropriate for hot rock both imaged cracks dip 60 to the northwest and strike northeast southwest along a direction parallel to the elongation of the volcanic edifice and a prominent zone of structural weakness as expressed by lineaments dikes and brittle structures for our data set the volume changes estimated from the moments are 200 m 3 for the largest explosion from each vent together with the volumetric source is a dominantly vertical force with a magnitude of 10 8 n consistent with the inferred movement of the magma column perched above the source centroid in response to the piston like rise of a slug of gas in the conduit index terms 7215 seismology earthquake parameters 7280 seismology volcano seismology 8419 8414 volcanology eruption mechanisms keywords very long period seismicity moment tensor inversions eruption mehanics

unusual lapilli tuff ejecta erupted at stromboli during the 15 march 2007 explosion shed light on the nature and thermal state of rocks forming the crater system of the volcano abstract textural and mineralogical study of high temperature angular blocks erupted during the stromboli explosion of 15 march 2007 was used to make inferences on the nature and thermal state of rocks forming the subsurface of the volcano summit crater terrace the studied ejecta consist of lapilli tuff that formed as a result of the transformation and high temperature induration sintering of the basaltic scoriae lapilli and ash originally accumulated as loose tephra during the current activity of the volcano the main processes leading to the tephra transformation were investigated through microstructural observations mineral and glass analyses sem eds and emp analyses investigations revealed that subsolidus reactions and partial melting of the tephra occurred at temperatures higher than 600 c and under variable fo 2 conditions from qfm to hm buffering curves in some blocks evidence of high t reheating and partial melting at the expense of secondary hydrothermal minerals was also observed in order to track the subsolidus reheating history of the basaltic pyroclasts a detailed study of the pseudomorphic phases and reactions after olivine driven by iron oxidation under high t conditions was performed the observed mineralogical transformation suggests that the lapilli tuff material originating from the burial of tephra routinely accumulated by persistent strombolian explosions within the crater terrace were in some cases altered by the circulation of acidic fluids and were in any case reheated due to isotherm rise forced by high heat flux and gas streaming delivered by the underlying magma system it is worth noting that the ejection of these unusual volcanic lithotypes was possible because a few days before the 15 march 2007 event the craters were clogged with lapilli tuff material that slid into the crater bottom between 7 and 9 march findings of this study suggest that the scattered permanently active vents and shallow conduits of stromboli are surrounded sideways and underneath the crater terrace by a fairly large volume of high temperature rocks with variable degree of compaction sintering up to partially melted such a spectrum of rock types is in good agreement with the conceptual model of prominent thermal zoning all around sideway and upwards the active magmatic system we speculate that continuous migration upwards of isotherms led to transformation and partial melting of the normal strombolian tephra

the 7 september 2008 vulcanian explosion at stromboli volcano multiparametric characterization of the event and quantification of the ejecta this paper was partially supported by a research project project ingv dpc paroxysm v2 03 2007 2009 funded by istituto nazionale di geofisica e vulcanologia and by the italian civil protection

bed load effects on hydrodynamics of rough bed open channel flows the extent to which turbulent structure is affected by bed load transport is investigated experimentally using a nonporous fixed planar bed comprising mixed sized granular sediment with a d50 of 1 95 mm three different sizes of sediment d50 0 77 1 99 and 3 96 mm were fed into the flow at two different rates 0 003 and 0 006 kg m s and subsequently transported as bed load particle image velocimetry piv was used to determine the turbulence characteristics over the fixed bed during clear water and sediment feed cases mean longitudinal flow velocities at any given depth were lower than their clear water counterparts for all but one of the mobile sediment cases the exception was with the transport of fine grains at the higher feed rate in this case longitudinal mean flow velocities increased compared to the clear water condition the coarse grains tended to augment bed roughness but fine grains saturated the troughs and interstices in the bed topography effectively causing the influence of bed irregularities to be smoothed the piv technique permitted examination of both temporal and spatial fluctuations in flow variables therefore many results are presented in terms of double averaged quantities in temporal and spatial domains in particular the form induced stress which arises from spatially averaging the reynolds averaged navier stokes equations and is analogous to the reynolds turbulent stress contributed between 15 and 35 of the total measured shear stress in the roughness layer flow around protrusive roughness elements produced a significant proportion of the turbulent kinetic energy shear production suggesting that this process is highly intermittent near rough beds

major eruptive style changes induced by structural modifications of a shallow conduit system the 2007 2012 stromboli case stromboli is known for its mild persistent explosive activity from the vents located within the summit crater depression at the uppermost part of the sciara del fuoco sdf depression effusive activity lava flows at this volcano normally occurs every 5 15 years involving often the opening of eruptive fissures along the sdf and more rarely overflows from the summit crater between the end of the 2007 effusive eruption and december 2012 the number of lava flows inside and outside the crater depression has increased significantly reaching a total of 28 with an average of 4 8 episodes per year an open question is why this activity has become so frequent during the last 6 years and was quite rare before in this paper we describe this exceptional activity and propose an interpretation based on the structural state of the volcano changed after the 2002 2003 and even more after the 2007 flank effusive eruption we use images from the stromboli fixed cameras network as well as ground photos plume so2 and co2 fluxes released by the summit crater and continuous fumarole temperature recording to unravel the interplay between magma supply structural and morphology changes and lava flow output our results might help forecast the future behaviour and hazard at stromboli and might be applicable to other open conduit volcanoes

dynamics of strombolian explosions inferences from field and laboratory studies of erupted bombs from stromboli volcano strombolian activity is characterized by repeated low energy explosions and is named after the volcano where such activity has persisted for around 2000 years i e stromboli aeolian islands italy stromboli represents an excellent laboratory where measurements of such explosions can be made from safe but close distances during a field campaign in 2008 two 15 cm diameter bombs were quenched and collected shortly after a normal explosion the bombs were characterized in terms of their textural chemical rheological and geophysical signatures the vesicle and crystal size distribution of the samples coupled with the glass chemistry enabled us to quantify variations in the degassing history and rheology of the magma resident in the shallow i e in last 250 m of conduit length the different textural facies observed in these bombs showed that fresh magma was mingled with batches of partially to completely degassed oxidized high crystallinity high viscosity evolved magma this magma sat at the top of the conduit and played only a passive role in the explosive process the fresh microlite poor vesiculated batch however experienced a response to the explosive event by undergoing rapid decompression integration of geophysical measurements with sample analyses indicates that popular bubble bursting models may not fit this case we suggest that the degassed magma forms a plug or rheological layer at the top of the conduit through which the fresh magma bursts in this model we need to consider the paradox of a slug ascending too fast through a magma of varying viscosity and yield strength

the 15 march 2007 paroxysm of stromboli video image analysis and textural and compositional features of the erupted deposit on 15 march 2007 a paroxysmal event occurred within the crater terrace of stromboli in the aeolian islands italy infrared and visible video recordings from the monitoring network reveal that there was a succession of highly explosive pulses lasting about 5 min from at least four eruptive vents initially brief jets with low apparent temperature were simultaneously erupted from the three main vent regions becoming hotter and transitioning to bomb rich fountaining that lasted for 14 s field surveys estimate the corresponding fallout deposit to have a mass of 1 9 107 kg that coupled with the video information on eruption duration provides a mean mass eruption rate of 5 4 105 kg s textural and chemical analyses of the erupted tephra reveal unexpected complexity with grain size bimodality in the samples associated with the different percentages of ash types juvenile lithics and crystals that reflects almost simultaneous deposition from multiple and evolving plumes juvenile glass chemistry ranges from a gas rich low porphyricity end member typical of other paroxysmal events to a gas poor high porphyricity one usually associated with low intensity strombolian explosions integration of our diverse data sets reveals that 1 the 2007 event was a paroxysmal explosion driven by a magma sharing common features with large scale paroxysms as well as with ordinary strombolian explosions 2 initial vent opening by the release of a pressurized gas slug and subsequent rapid magma vesiculation and ejection which were recorded both by the infrared camera and in the texture of fallout products and 3 lesser paroxysmal events can be highly dynamic and produce surprisingly complex fallout deposits which would be difficult to interpret from the geological record alone

the 2009 paroxysmal explosions at stromboli italy magma mixing and eruption dynamics three small scale paroxysmal explosions also called major explosions interrupted ordinary mild strombolian activity at stromboli on may 3 november 8 and 24 2009 products were largely confined to the summit area except in the november 24 event during which coarse pumiceous lapilli reached the coast emission of crystal poor pumice closely mingled with crystal rich products characterized the three events the textural and chemical study of minerals and glassy matrices revealed that the two end members are mingled together physically in the may 3 and november 24 pumice whereas november 8 products contain heterogeneous glass with intermediate compositions derived from chemical mixing between crystal rich and crystal poor magmas we here discuss the different degrees of interaction between the two magmas in the three explosions in terms of magma dynamics during small scale paroxysms

the stromboli 2002 tsunamigenic submarine slide characteristics and possible failure mechanisms 1 on 30 december 2002 a major instability event deeply involving the submarine slope occurred on the sciara del fuoco on the western flank of stromboli volcano in the aeolian islands tsunami waves with a maximum runup of over 10 m in stromboli were generated having a measurable impact as far as the sicily coast just 10 months before the event a multibeam bathymetry had been collected in the area down to 1000 m of depth a repetition of the survey after the slide allowed the unique opportunity to verify the occurrence of a large submarine slide and to define volumes involved and morphology generated by the event through the comparison of the preevent and postevent bathymetric grids a morphological characterization of the slope before and after the submarine landslide is presented showing how the preexisting features interacted with the slide event in controlling the instability mechanisms of the submarine failure are discussed on the basis of the geometrical characters of the landslide event structural and stratigraphic setting of the submerged slope and geotechnical considerations on the behavior of slope material

shrimp ionprobe dating of short lived proterozoic tectonic cycles in the northern arunta inlier central australia structural and metamorphic evidence from low p high t metamorphic terranes within the northern arunta inlier central australia indicates that two discrete tectonic cycles affected the region each cycle was associated with compressive deformation coincident with peak granulite facies metamorphism and granite intrusion shrimp u th pb analysis of zircons from early syn and late tectonic granitoids allows the age of the two tectonic cycles to be directly measured the age of the first cycle d1 is determined by emplacement of the mount stafford granite dated at or before 1818 15 ma after the first two foliations of the cycle had formed but before the axial plane cleavage associated with later upright folding the regional extent of this tectono magmatic event is confirmed by an emplacement age of 1818 8 ma measured on the large discordant harverson granite 40 km away the second cycle d2 consisted of four distinct deformation stages d2a 2d the ages of which are constrained by 1785 1775 ma old early syn and late tectonic granitoids the warimbi granite emplaced at or before 1785 22 ma and the granitic protolith to the napperby gneiss inferred to be 1780 10 ma pre date or formed during the earliest foliation s2a zircon considered to have grown at peak granulite facies metamorphic conditions during generation of the dominant s2b foliation gives an age of 1774 6 ma in the possum creek charnockite leucogranite in the napperby gneiss which post dates s2b and large scale upright nw se trending f2d folds yields an age of 1775 12 ma and confirms that the entire tectonic cycle d2a 2d formed in a rapid 10 ma period younger zircons which formed at 1659 6 ma in the napperby gneiss cannot be related to any local structural event but are similar in age to a major magmatic metamorphic episode in the southern arunta black and shaw 1992 150 km away they may be the peripheral manifestation of that event further zircon growth at 1600 ma in the napperby gneiss and possum creek charnockite was caused by hydrothermal fluid fluxing associated with post tectonic pegmatite emplacement these dykes were deformed by amphibolite facies retrograde shear zones ion probe dating of zircon stratigraphy from the granitoids has confirmed the discrete successive tectonic cycles identified by earlier structural and metamorphic studies for the northern arunta inlier at least those cycles or orogenies are associated with short lived 10 ma thermal pulses related to granite magmatism not prolonged thermal perturbations spanning 100 ma or more cf dirks and wilson 1990 dirks and hand 1991 such short lived pulses are intimately associated with granite intrusion and may be a general feature of low p high t metamorphism

stromboli 2007 eruption deflation modeling to infer shallow intermediate plumbing system 1 during the effusive phase of the stromboli 2007 eruption the gps and tilt stations recorded small but significant changes which for the first time at this volcano clearly indicated a deflation we modeled the deflation inferring a depressurizing vertically elongated source with centre under the volcano edifice about 2 8 km below sea level the model whose position is above the magma source region inferred by petrological studies and the associated rapid deflation suggest a near free pathway for magma ascent from this source to the upper shallow conduit

dyke emplacement and related hazard in volcanoes with sector collapse the 2007 stromboli italy eruption in february 2007 two effusive vents opened along the flank of sciara del fuoco depression at stromboli the summit craters collapsed obstructing the central conduit choking the vents and increasing the deformation within sciara del fuoco here a new vent opened releasing the excess magmatic pressure the eruption continued after a summit explosion until april the vents were fed by laterally propagating dykes vent location is similar to that of the 2002 2003 eruption that eruption was fed by dykes triggering landslides which in turn produced a tsunami however the 2007 eruption did not develop landslides suggesting that their triggering also depends on other factors i e magmatic pressure

the 2007 eruption of stromboli volcano insights from real time measurement of the volcanic gas plume co2 so2 ratio abstract the recent eruption of stromboli in february april 2007 offered a unique chance to test our current understanding of processes driving the transition from ordinary persistent strombolian to effusive activity and the ability of instrumental geophysical and geochemical networks to interpret and predict these events here we report on the results of two years of in situ sensing of the co 2 so 2 ratio in stromboli s volcanic gas plume in the attempt to put constraints on the trigger mechanisms and dynamics of the eruption we show that large variations of the plume co 2 so 2 ratio range 0 9 26 preceded the onset of the eruption since december 2007 interrupting a period of relatively steady and low ratios time averaged ratio 4 3 lasting from at least may to november 2006 by contrasting our observations with numerical simulations of volcanic degassing at stromboli derived by use of an equilibrium saturation model we suggest that the pre eruptive increase of the ratio reflected an enhanced supply of deeply derived co 2 rich gas bubbles to the shallow plumbing system this larger than normal ascent of gas bubbles was likely sourced by a 1 3 km deep gas melt separation region probably a magma storage zone and caused faster convective overturning of magmas in the shallow conduit an increase in the explosive rate and in seismic tremor and finally the collapse of the la sciara del fuoco sector triggering the effusive phase the high co 2 so 2 ratios up to 21 observed during the effusive phase and particularly in the days and hours before a paroxysmal explosion on march 15 2007 indicate the persistence of the same gas source and suggest that de pressurization of the same 1 3 km deep magma storage zone could have been the trigger mechanism for the paroxysm itself

the 5 april 2003 vulcanian paroxysmal explosion at stromboli volcano italy from field observations and thermal data abstract the 5 april 2003 paroxysmal explosion at stromboli volcano was one of the strongest explosive events of the last century it occurred while the effusive eruption begun on 28 december 2002 and finished on 22 july 2003 was still on going and the summit craters of the volcano were obstructed in this paper we present a reconstruction of the sequence of events based on thermal and visual images collected from helicopter before during and immediately after the paroxysm one month before the blast ash emission and temperature increase at the bottom of the summit craters were observed an increasing amount of juvenile components in the emitted ash during march suggested that the magma level within the crater was rising accordingly hot degassing vents at the bottom of the summit craters were not persistent and the craters remained almost entirely obstructed by talus accumulation until the paroxysm occurred three minutes before the explosion we recorded a significant increase in temperature inside crater 1 accompanied by a thicker gas plume thirty two seconds before the blast reddish ash was emitted from crater 1 the paroxysm produced a vulcanian explosion that opened the feeder conduit obstructed for over three months the blast was accompanied by a shock wave recorded by the ingv seismic network at 07 13 37 gmt explosions with hot material started from crater 1 and after 15 s propagated to crater 3 about 100 m away the velocity of ejecta was 80 m s 1 and increased when the eruptive plumes from both craters merged together during the vulcanian phase an eruptive column rose 1 km above the top of the volcano and explosions continued mainly at crater 3 the paroxysm lasted about 9 min with bombs up to 4 m wide falling on the village of ginostra on the west flank of the island and destroying two houses this event signalled the start of the declining phase of the effusive eruption suggesting that the feeder conduit was returning to its former steady conditions with open vents and continuous mild strombolian activity

the ground based insar monitoring system at stromboli volcano linking changes in displacement rate and intensity of persistent volcanic activity stromboli volcano aeolian archipelago southern italy experienced an increase in its volcanic activity from late december 2012 to march 2013 when it produced several lava overflows major strombolian explosions crater wall collapses pyroclastic density currents and intense spatter activity an analysis of the displacement of the ne portion of the summit crater terrace and the unstable nw flank of the volcano sciara del fuoco depression has been performed with a ground based interferometric synthetic aperture radar gbinsar by dividing the monitored part of the volcano into five sectors three in the summit vents region and two in the sciara del fuoco changes in the displacement rate were observed in sectors 2 and 3 field and thermal surveys revealed the presence of an alignment of fumaroles confirming the existence of an area of structural discontinuity between sectors 2 and 3 high displacement rates in sector 2 are interpreted to indicate the increase in the magmastatic pressure within the shallow plumbing systems related to the rise of the magma level within the conduits while increased displacement rates in sector 3 are connected to the lateral expansion of the shallow plumbing system the increases and decreases in the displacement rate registered by the gbinsar system in the upper part of the volcano have been used as a proxy for changes in the pressure conditions in the shallow plumbing system of stromboli volcano and hence to forecast the occurrence of phases of higher intensity volcanic activity

evidence of a dyke sheet intrusion at stromboli volcano inferred through continuous tilt a tiltmeter installed in the northern sector of the island of stromboli aeolian archipelago tyrrhenian sea recorded a co seismic offset at the time of the main shock ml 3 7 of the 7 november 1994 swarm located 5 km north of the island during the three months following this event a transient tilt anomaly which was interpreted as due to a lateral intrusion and modelled through a dyke sheet dislocation was recorded the tilt data were used in an analytical inversion based on a propagating tensile source with length and width increasing in time the final result is consistent with the tectonic and structural framework of the volcano area

an unloading foam model to constrain etna s 11 13 january 2011 lava fountaining episode 1 the 11 13 january 2011 eruptive episode at etna volcano occurred after several months of increasing ash emissions from the summit craters and was heralded by increasing so2 output which peaked at 5000 megagrams day several hours before the start of the eruptive activity the eruptive episode began with a phase of strombolian activity from a pit crater on the eastern flank of the se crater explosions became more intense with time and eventually became transitional between strombolian and fountaining before moving into a lava fountaining phase fountaining was accompanied by lava output from the lower rim of the pit crater emplacement of the resulting lava flow field as well as associated lava fountain and strombolian phases was tracked using a remote sensing network comprising both thermal and visible cameras thermal surveys completed once the eruptive episode had ended also allowed us to reconstruct the emplacement of the lava flow field using a high temporal resolution geostationary satellite data we were also able to construct a detailed record of the heat flux during the fountain fed flow phase and its subsequent cooling the dense rock volume of erupted lava obtained from the satellite data was 1 2 106 m3 this was emplaced over a period of about 6 h to give a mean output rate of 55 m3 s 1 by comparison geologic data allowed us to estimate dense rock volumes of 0 85 106 m3 for the pyroclastics erupted during the lava fountain phase and 0 84 1 7 106 m3 for lavas erupted during the effusive phase resulting in a total erupted dense rock volume of 1 7 2 5 106 m3 and a mean output rate of 78 117 m3 s 1 the sequence of events and quantitative results presented here shed light on the shallow feeding system of the volcano

structural features of the 2007 stromboli eruption abstract on 27 february 2007 two ne sw and nnw sse dike fed effusive vents opened to the north at 650 and 400 m above sea level asl of the summit craters at stromboli forming a fissure parallel to the inner walls of the sciara del fuoco sdf sector collapse depression the formation of these vents was soon followed by rapid subsidence of the summit crater area this partly obstructed the central conduit temporarily choking the fissure and increasing the deformation of the upper part of sdf the reactivation of the nnw sse vent and the opening of a new vent located at 500 m asl fed by a second dike released the internal pressure and surface deformation ceased the eruption then continued again from the 400 m vent after a summit explosion on 15 march until ending in early april after a progressive decrease of magma output repeated ne sw dike intrusions have occurred in recent years close to the upper se limit of the sdf in that zone named bastimento the eruptive fractures traced the discontinuities that borders the sdf increasing the risk of triggering new sector collapse whereas the ne sw trending structures lie along the regional volcano structural trend of the aeolian arc through stromboli the nnw sse vents are oblique to this trend and may be controlled by the anomalous stress field within the unstable flank of the sdf another fundamental aspect of the 2007 eruption is the collapse of the central conduit due to the rapid and deep magma drainage linked to the opening of the 400 m vent the intrusion of dikes and development of flank vents during the 2007 eruption could possibly have triggered catastrophic landslides and related tsunami or eruptive paroxysms but the opening of new effusive vents released the internal pressures diminishing the hazard

sliding episodes during the 2002 2003 stromboli lava effusion insights from seismic volcanic and statistical data analysis 1 repeated phenomena of flank instability accompanied the 28 december 2002 to 21 july 2003 eruption of stromboli volcano the major episodes were two tsunamigenic landslides on 30 december 2002 2 d after the volcano unrest after 30 december sliding processes remodeled the area affected by slope instability we propose analyses of 565 sliding episodes taking place from december 2002 to february 2003 we try to shed light on their main seismic features and links with the ongoing seismic and volcanic activity using variogram analysis as well a characterization of the seismic signals in the time and frequency domains is presented for 185 sliding episodes their frequency content is between 1 hz and 7 hz on the basis of the dominant peaks and shape of the spectrum we identify three subclasses of signals one of which has significant energy below 2 hz low frequency signatures were also found in the seismic records of the landslides of 30 december which affected the aerial and submarine northwestern flank of the volcano accordingly we surmise that spectral analysis might provide evidence of sliding phenomena with submarine runouts we find no evidence of sliding processes induced by earthquakes additionally a negative statistical correlation between sliding episodes and explosion quakes is highlighted by variogram analysis variograms indicate a persistent behavior memory of the flank instability from 5 to 10 d we interpret the climax in the occurrence rate of the sliding processes between 24 and 29 january 2003 as the result of favorable conditions to slope instability due to the emplacement of nw se aligned dike fed vents located near the scarp of the landslide area afterward the stabilizing effect of the lava flows over the northwestern flank of the volcano limited erosive phenomena to the unstable loose slope not covered by lava

time variability of low temperature fumaroles at stromboli island italy and its application to volcano monitoring the constant and mild activity of stromboli volcano italy is occasionally interrupted by effusive events and or more energetic explosions referred to as major explosions and paroxysms which are potentially dangerous for the human community although several premonitory signals for effusive phases have been identified precursors of major explosions and paroxysms still remain poorly understood with the aim of contributing to the identification of possible precursors of energetic events this work discusses soil temperature data acquired in low temperature fumaroles at stromboli in the period 2006 2010 data analysis revealed that short term anomalies recorded in the thermal signal are potentially useful in predicting state changes of the volcano in particular sudden changes in fumarole temperatures and their hourly gradients were observed from several days to a few hours prior to fracturing and paroxysmal events heralded by peculiar waveforms of the recorded signals the qualitative interpretation is supported by a quantitative theoretical treatment that uses circuit theory to explain the time dependence of the short period temperature variations showing a good agreement between theoretical and observational data

interpretation of data from the monitoring thermal camera of stromboli volcano aeolian islands italy twenty eruptive events from the northeast crater of stromboli volcano recorded by a thermal monitoring camera in early 2004 were analysed in order to understand the eruptive dynamics selected events were chosen to be typical of explosions that characterize the steady activity of stromboli in terms of jet height and duration most of the explosions consisted of clast rich single bursts originating from the same vent inside the northeast crater conspicuous ash emission was scarce eruptions were preceded by the flashing of a perturbation wave characterized by low temperatures and an average propagation velocity of about 35 100 m s 1 this perturbation was thought to be caused by the bursting of the gas slug at the bottom of the crater and is interpreted as an air wave this was immediately followed by the expansion of a jet of hot gas and particles at a velocity of 35 75 m s 1 ejecta coarser than 138 cm appeared 1 6 2 s after the onset of the explosion moving at a variable velocity 30 60 m s 1 eruptive events were either vertical or inclined 7 13 towards the nnw this inclination is thought to be a consequence either of the morphology of the conduit following modest rock falls that partially obstructed the uppermost part of the crater or of the displacement of the internal conduit due to the explosive activity of the volcano the instability of the summit area is a further possible cause of the deformation of the conduit

contemporary total dissolved gas pressure and soil temperature anomalies recorded at stromboli volcano italy 1 soil temperature and total dissolved gas pressure tdgp data were recorded by two continuous monitoring stations on the volcano of stromboli italy between march and october 2006 during this period several tdgp and soil temperature anomalies unrelated to external causes and characterized by a similar shape and occurrence time were recorded these anomalies were interpreted as transients due to changes in the degassing regime of the volcano which was in turn related to changes in the partition ratio of the volcanic fluids between the conduit and the soil in the same period stromboli experienced an anomalous phase of volcanic and tectonic activity the close correlation found between volcano tectonic activity and variations in anomalous monitored parameters suggests that their continuous monitoring may be a useful tool for the surveillance of volcanic activity on the island

so2 flux from stromboli during the 2007 eruption results from the flame network and traverse measurements abstract so 2 fluxes emitted by stromboli during the 27th february 2nd april 2007 effusive eruption were regularly measured both by an automatic network of scanning ultraviolet spectrometers and by traverse measurements conducted by boat and helicopter the results from both methodologies agree reasonably well providing a validation for the automatic flux calculations produced by the network approximately 22 000 t of so 2 were degassed during the course of the 35 day eruption at an average rate of 620 t per day such a degassing rate is much higher than that normally observed 150 200 t d because the cross sectional area occupied by ascending degassed magma is much greater than normal during the effusion as descending degassed magma that would normally occupy a large volume of the conduit is absent we propose that the hydrostatically controlled magma level within stromboli s conduit is the main control on eruptive activity and that a high effusion rate led to the depressurisation of an intermediate magma reservoir creating a decrease in the magma level until it dropped beneath the eruptive fissure causing the rapid end of the eruption a significant decrease in so 2 flux was observed prior to a paroxysm on 15th march 2007 suggesting that choking of the gas flowing in the conduit may have induced a coalescence event and consequent rapid ascent of gas and magma that produced the explosion

three years of so2 flux measurements of mt etna using an automated uv scanner array comparison with conventional traverses and uncertainties in flux retrieval 1 sviluppo di sistemi di monitoraggio dipartimento di protezione civile della regione sicilia 2 ingv istituto nazionale di geofisica e vulcanologia sezione di catania italy 3 novac network for observation of volcanic and atmospheric change eu funded sixth framework programme project 18354 4 uk nerc national centre for earth observation via the dynamic earth and geo hazards