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

volcanic tremor at mt etna italy preceding and accompanying the eruption of july august 2001 the july 17 august 9 2001 flank eruption of mt etna was preceded and accompanied by remarkable changes in volcanic tremor based on the records of stations belonging to the permanent seismic network deployed on the volcano we analyze amplitude and frequency content of the seismic signal we find considerable changes in the volcanic tremor which mark the transition to different styles of eruptive activity e g lava fountains phreatomagmatic activity strombolian explosions in particular the frequency content of the signal decreases from 5 hz to 3 hz at our reference station etf during episodes of lava fountains and further decreases at about 2 hz throughout phases of intense lava emission the frequency content and the ratios of the signal amplitude allow us to distinguish three seismic sources i e the peripheral dike which fed the eruption the reservoir which fed the lava fountains and the central conduit based on the analysis of the amplitude decay of the signal we highlight the migration of the dike from a depth of ca 5 km to about 1 km between july 10 and 12 after the onset of the effusive phase the distribution of the amplitude decay at our stations can be interpreted as the overall result of sources located within the first half kilometer from the surface although on a qualitative basis our findings shed some light on the complex feeding system of mt etna and integrate other volcanological and geophysical studies which tackle the problem of magma replenishment for the july august 2001 flank eruption we conclude that volcanic tremor is fundamental in monitoring mt etna not only as a marker of the different sources which act within the volcano edifice but also of the diverse styles of eruptive activity

spectroscopic evidence for a lava fountain driven by previously accumulated magmatic gas the eruption of mount etna in 2000 was notable for an exceptional series of 64 periodic lava fountains propelling lava fragments to heights of up to 900 metres it has been difficult to determine which of two suggested sources of power gas release from the magma itself during its rapid ascent or a build up of pressure from gas accumulated at depth is the driving force for these dramatic jets but one of the etna fountains provided volcanologists with the opportunity to use remote sensing not that remote see picture on the following page to determine the infrared spectra of the gas phase this revealed the chemical composition of the gas that powered this fountain as consistent with an origin in an accumulated gas layer lava fountains are spectacular continuous gas jets propelling lava fragments to heights of several hundred metres which occasionally occur during eruptions of low viscosity magmas1 2 3 4 5 whether they are generated by the effervescent disruption of fast rising bubbly melt2 3 4 5 or by the separate ascent of a bubble foam layer accumulated at depth6 7 still remains a matter of debate8 no field measurement has yet allowed firm discrimination between these two models a key insight into the origin of lava fountains may be gained by measuring the chemical composition of the driving gas phase this composition should differ markedly depending on whether the magma degassing occurs before or during eruption9 10 here we report the analysis of magmatic gas during a powerful 250 600 m high lava fountain measured with fourier transform infrared spectroscopy11 12 13 14 on mount etna sicily the abundances of volcanic gas species determined from absorption spectra of lava radiation reveal a fountain gas having higher co2 s and s cl ratios than other etnean emissions14 15 16 17 18 and which cannot derive from syn eruptive bulk degassing of etna basalt19 20 instead its composition suggests violent emptying of a gas bubble layer previously accumulated at about 1 5 km depth below the erupting crater

composite ground deformation pattern forerunning the 2004 2005 mount etna eruption 1 after the end of the 2002 2003 eruption mount etna activity was characterized only by gentle degassing at the summit craters and some earthquake swarms suddenly an eruption started on 7 september 2004 in complete absence of summit crater volcanic activity seismicity or seismic tremor and ground deformation this is the first time that magma poured out passively without preeruptive and coeruptive volcanic and or geophysical phenomena the primary key to understanding this event is represented by the ground deformation pattern recorded through gps measurements during the year before the eruption the ground deformation shows inflation superimposed by a predominant eastward movement of the eastern sector at a rate never observed before in a noneruptive period the images from satellite radar interferometry confirmed this pattern the deformation field clearly shows that the maximum tension in the eastern sector of the volcano caused the opening of the eruptive fracture which favored the silent pouring out of already resident magma

dynamics of a lava fountain revealed by geophysical geochemical and thermal satellite measurements the case of the 10 april 2011 mt etna eruption 1 geophysical tilt seismic tremor and gravity signals geochemical crater so2flux and infrared satellite measurements are presented and discussed to track the temporal evolution of the lava fountain episode occurring at mt etna volcano on 10 april 2011 the multi disciplinary approach provides insight into a gas rich magma source trapped in a shallow storage zone inside the volcano edifice this generated the fast ascending gas magma dispersed flow feeding the lava fountain and causing the depressurization of a deeper magma storage satellite thermal data allowed estimation of the amount of erupted lava which summed to the tephra volume yielded a total volume of erupted products of about 1 106 m3 thanks to the daylight occurrence of this eruptive episode the so2 emission rate was also estimated showing a degassing cycle reaching a peak of 15 000 mg d 1 with a mean daily value of 5 700 mg d 1 the so2 data from the previous fountain episode on 17 18 february to 10 april 2011 yielded a cumulative degassed magma volume of about 10 5 106 m3 indicating a ratio of roughly 10 1 between degassed and erupted volumes this volumetric balance differently from those previously estimated during different styles of volcanic activities with long term years recharging periods and middle term weeks to months effusive eruptions points toward the predominant role played by the gas phase in generating and driving this lava fountain episode

the origin of the fluid mud layer in lake apopka florida since it switched from a macrophyte dominated state to a turbid algal dominated state in 1947 lake apopka has developed a layer of flocculent sediments with characteristics of fluid mud covering most of the lakebed and averaging 47 cm in thickness in 1996 waves in this large shallow lake frequently resuspend the upper portion of the fluid mud and frustrate programs designed to decrease the trophic state we tested two hypotheses for its origin one that the fluid mud layer represents the buildup of organic materials that had accumulated since 1947 the other that it was derived primarily by the liquefaction of the underlying macrophyte derived consolidated sediments we examined 1 changes in the mean depth of the lake relative to changes in fluid mud thickness 2 210 pb dating of the sediments 3 organic matter budget for the lake 4 inorganic particle budget for the lake and 5 chemical markers of sediments produced during the macrophyte stage biogenic silica from sponges long chain n alkanes from macrophytes and 13 c in the fluid mud the evidence indicates that a major portion of the fluid mud can be attributed to the liquefaction of underlying consolidated sediments that were produced during the macrophyte stage of the lake it follows that the fluid mud layer is less a direct consequence of eutrophication than a consequence of enhanced wave action on the lakebed following the loss of macrophyte dominance in this lake

magma storage eruptive activity and flank instability inferences from ground deformation and gravity changes during the 1993 2000 recharging of mt etna volcano abstract a long recharging period characterized mount etna volcano during 1993 2000 before the main explosive effusive 2001 and 2002 2003 flank eruptions the joint analysis of ground deformation and gravity data over the recharge period reveals that different phenomena occurred within etna s plumbing system and clearly indicates two phases spanning 1993 1997 and 1997 2000 respectively the first phase was characterized by magma storage and accumulation at an intermediate depth 2 6 km below sea level which provoked overall inflation and positive gravity changes during the second phase the magma started to rise and intrude at shallower levels favoring the movement of the unstable eastern flank which accelerated its sliding toward the east the shallower magma accumulation also caused the gas exsolution associated with increasing explosive activity at the summit craters negative gravity changes were detected during this phase the gravity measurements independent of the same result obtained by geochemical studies suggest that only 20 30 of the magma volumes supplied in the plumbing system were then erupted the complex dynamics of rising magma beneath mount etna makes ground deformation and gravity measurements complementary being able to detect different effects of magma emplacements beneath the surface our results also highlight how the joint use of ground deformation and gravity observations may be crucial in identifying the nature and rate of an impending period of volcanic eruptions

melt inclusion record of the conditions of ascent degassing and extrusion of volatile rich alkali basalt during the powerful 2002 flank eruption of mount etna italy 1 two unusual highly explosive flank eruptions succeeded on mount etna in july august 2001 and in october 2002 to january 2003 raising the possibility of changing magmatic conditions here we decipher the origin and mechanisms of the second eruption from the composition and volatile h2o co2 s cl content of olivine hosted melt inclusions in explosive products from its south flank vents our results demonstrate that powerful lava fountains and ash columns at the eruption onset were sustained by closed system ascent of a batch of primitive volatile rich 4 wt basaltic magma that rose from 10 km depth below sea level bsl and suddenly extruded through 2001 fractures maintained opened by eastward flank spreading this magma the most primitive for 240 years probably represents the alkali rich parental end member responsible for etna lavas evolution since the early 1970s few of it was directly extruded at the eruption onset but its input likely pressurized the shallow plumbing system several weeks before the eruption this latter was subsequently fed by the extrusion and degassing of larger amounts of the same but slightly more evolved magma that were ponding at 6 4 km bsl in agreement with seismic data and with the lack of preeruptive so2 accumulation above the initial depth of sulphur exsolution 3 km bsl we find that while ponding this magma was flushed and dehydrated by a co2 rich gas phase of deeper derivation a process that may commonly affect the plumbing system of etna and other alkali basaltic volcanoes

an investigation into shallow borehole tiltmeters shallow borehole tiltmeters are frequently used for ground deformation monitoring in volcanic areas where they are usually installed within a few meters of the surface a major problem concerns the noise affecting the installation at shallow depth where large tilt and strain are caused by temperature effects the long term stability of these instruments and the best shallow depth of installation in terms of best cost benefit are the crucial points we conducted an experiment in order to compare the signals of three shallow borehole electronic tiltmeters installed in the same place at different depths we verified the signal reliability in revealing the long term slow deformation and looked into the reduction of the temperature effects with depth we present three years of data and discuss the limits and the advantages of the different installation depths

feeding system and magma storage beneath mt etna as revealed by recent inflation deflation cycles 1 ground deformation at mt etna detected by three gps surveys carried out in 2004 2005 and 2006 is analyzed the data set encompasses the 2004 2005 eruptions and foreruns those of 2006 a wide deflation of the entire volcano was detected from 2004 to 2005 accompanying the 2004 2005 eruption conversely an evident inflation phase from 2005 to 2006 followed this eruption and preceded the 2006 one in both cases the deflation inflation cycle was accompanied by a continuous seaward motion of the eastern flank we inverted both data sets 2004 2005 deflation and 2005 2006 inflation using an optimization algorithm based on the genetic algorithm ga in order to detect the ground deformation sources the wide contraction measured during the eruption reveals the drainage of a sill shaped magma reservoir located by data inversions at a depth of about 4 5 km b s l the pressurizing source modeled for the 2005 2006 time interval indicates a refilling of the shallower near vertical plumbing system of the volcano this could indicate a change in the geometry of the feeding system active after the 2004 2005 eruption with a new and shallower magma storage that could have enabled the resumption of volcanic activity that was observed at summit craters in 2006 these results improve the imaging of the plumbing system of mt etna volcano

the exceptional activity and growth of the southeast crater mount etna italy between 1996 and 2001 between 1971 and 2001 the southeast crater was the most productive of the four summit craters of mount etna with activity that can be compared on a global scale to the opening phases of the pu u k paianaha eruption of k lauea volcano hawai i the period of highest eruptive rate was between 1996 and 2001 when near continuous activity occurred in five phases these were characterized by a wide range of eruptive styles and intensities from quiet non explosive lava emission to brief violent lava fountaining episodes much of the cone growth occurred during these fountaining episodes totaling 105 events many showed complex dynamics such as different eruptive styles at multiple vents and resulted in the growth of minor edifices on the flanks of the southeast crater cone small pyroclastic flows were produced during some of the eruptive episodes when oblique tephra jets showered the steep flanks of the cone with hot bombs and scoriae fluctuations in the eruptive style and eruption rates were controlled by a complex interplay between changes in the conduit geometry including the growth of a shallow magma reservoir under the southeast crater magma supply rates and flank instability during this period volume calculations were made with the aid of gis and image analysis of video footage obtained by a monitoring telecamera between 1996 and 2001 the bulk volume of the cone increased by 36 106 m3 giving a total 1971 2001 volume of 72 106 m3 at the same time the cone gained 105 m in height reaching an elevation of about 3 300 m the total dre volume of the 1996 2001 products was 90 106m3 this mostly comprised lava flows 72 106 m3 erupted at the summit and onto the flanks of the cone these values indicate that the productivity of the southeast crater increased fourfold during 1996 2001 with respect to the previous 25 years coinciding with a general increase in the eruptive output rates and eruption intensity at etna this phase of intense summit activity has been followed since the summer of 2001 by a period of increased structural instability of the volcano marked by a series of important flank eruptions

near real time forecasting of lava flow hazards during the 12 13 january 2011 etna eruption we are grateful to eumetsat for seviri data to nasa for modis data and tonoaafor avhrr data the authors thank one anonymous reviewer and v acocella for their helpful and constructive comments this study was performed with the financial support from the v3 lava project ingv dpc 2007 2009 contract

relationship between tremor and volcanic activity during the southeast crater eruption on mount etna in early 2000 1 the southeast crater of mount etna italy was characterized by a violent eruptive activity between 26 january and 24 june 2000 this activity produced 64 lava fountain episodes with repose periods from 3 hours to 10 days we estimated a volume of about 15 20 106 m3 lava and at least 2 3 106 m3 of tephra we compared the paroxysmal volcanic activity to its associated seismic signature the high number of events highlighted a strict correlation between tremor and volcanic activity seismic and volcanic characteristics such as the frequency of occurrence the duration of lava fountains and the associated tremor energy suggested the subdivision of the studied period into two stages separated by the 20 february event combining volcanic with seismic data we observed some useful relationships among lava fountain height sustained column height and reduced displacement in addition we found that the entire episode was well correlated with the duration of the amplitude increase computing the tremor energy linked to each event the total energy associated with lava fountains episodes results in 76 of the energy released during the whole period finally the different ratios among the overall spectral amplitude of the seismic signals of the stations located at different altitudes suggested to us the elaboration of a simple qualitative model to explain the dynamic behavior of the tremor source during the whole episode

explosive activity at mt etna summit craters and source modeling by using high precision continuous tilt we investigated the relationships between modelled strain produced by explosive activity through a volcanic conduit observed paroxystic episodes on mt etna and high precision continuous tilt signals recorded during such events from the tilt monitoring network the tilt changes detected during two different explosive episodes were compared with those calculated from analytical models of ground deformation in order to constrain source properties the july 22 1998 subplinian explosion from voragine crater produced small tilt changes order of 0 5 1 5 rad recorded over the entire volcano edifice implying a small storage at nearly 2 5 km below sea level the 1998 2000 period was characterized by tens of spectacular lava fountains from the south east crater very small tilt change 0 1 rad was recorded by a single station on the high north eastern flank of mt etna and indicated the action of a limited and shallow conduit with 1 5 1 9 km depth these results provide a contribution to better infer the shallow plumbing system beneath mt etna

factors influencing the height of hawaiian lava fountains implications for the use of fountain height as an indicator of magma gas content the heights of lava fountains formed in hawaiian style eruptions are controlled by magma gas content volume flux and the amounts of lava re entrainment and gas bubble coalescence theoretical models of lava fountaining are used to analyse data on lava fountain height variations collected during the 1983 1986 pu u o o vent of kilauea volcano hawaii the results show that the variable fountain heights can be largely explained by the impact of variations in volume flux and amount of lava re entrainment on erupting magmas with a constant gas content of 0 32 wt h2o however the gas content of the magma apparently declined by 0 05 wt during the last 10 episodes of the eruption series and this decline is attributed to more extensive pre eruption degassing due to a shallowing of the sub vent feeder dike it is concluded that variations in lava fountain height cannot be simply interpreted as variations in gas content as has previously been suggested but that fountain height can still be a useful guide to minimum gas contents where sufficient data are available on eruptive volume fluxes and extent of lava entrainment greatly improved estimates can be made of magma gas content from lava fountain height

volcanic tremor location during the 2004 mount etna lava effusion 1 a lava emission started at mt etna italy on 7 september 2004 neither earthquake seismicity heralded or accompanied the opening of the fracture field from which the lava poured out nor volcanic tremor changed in amplitude and frequency content at the onset of the effusive activity to highlight long term changes we propose a method for the location of the tremor source based on a 3d grid search using the amplitude decay of the seismic signal from january to november 2004 we find the centroid of the tremor source within a zone close to and partially overlapped with the summit craters pre effusive phase which extended up to 2 km south of them effusive phase the depths are of between 1698 and 2387 m a s l we hypothesize the lava effusion stemmed from a degassed magma body although we find evidence of temporary magma overpressure conditions such as those documented on 25 september

the initial phases of the 2008 2009 mount etna eruption a multidisciplinary approach for hazard assessment accepted for publication in journal of geophysical research copyright 2010 american geophysical union

lava effusion rate definition and measurement a review measurement of effusion rate is a primary objective for studies that model lava flow and magma system dynamics as well as for monitoring efforts during on going eruptions however its exact definition remains a source of confusion and problems occur when comparing volume flux values that are averaged over different time periods or spatial scales or measured using different approaches thus our aims are to 1 define effusion rate terminology and 2 assess the various measurement methods and their results we first distinguish between instantaneous effusion rate and time averaged discharge rate eruption rate is next defined as the total volume of lava emplaced since the beginning of the eruption divided by the time since the eruption began the ultimate extension of this is mean output rate this being the final volume of erupted lava divided by total eruption duration whether these values are total values i e the flux feeding all flow units across the entire flow field or local i e the flux feeding a single active unit within a flow field across which many units are active also needs to be specified no approach is without its problems and all can have large error up to 50 however good agreement between diverse approaches shows that reliable estimates can be made if each approach is applied carefully and takes into account the caveats we detail here there are three important factors to consider and state when measuring giving or using an effusion rate first the time period over which the value was averaged second whether the measurement applies to the entire active flow field or a single lava flow within that field and third the measurement technique and its accompanying assumptions

evidence of deep magma degassing and ascent by geochemistry of peripheral gas emissions at mount etna italy assessment of the magmatic reservoir pressure 1 five gas discharges in the area of mount etna volcano italy and in the near hyblean plateau have been monitored since 1996 all the emissions displayed low contributions from crustal fluids whereas magmatic gases were the main component selective dissolution of these gases into hydrothermal aquifers has been recognized and modeled allowing us to calculate the original composition of the magma released gases the inferred composition of the magmatic gases exhibits synchronous variations of he ne and he co2 ratios which are coherent with the magma degassing process on the basis of numerical simulations of volatile degassing from etnean basalts we have computed the initial and final pressures of the magma batches feeding the emissions we thus can define the levels of the etna plumbing system where magmas are stored pressure values were around 360 and 160 mpa for initial and final stages respectively meaning related depths of about 10 and 3 km below sea level matching those obtained by geophysical investigations for the deep and shallow magma reservoirs in addition we have been able to recognize episodes of magma migration from the deeper reservoir toward the shallow one an important magma injection into the shallow storage volume was detected during the onset of the 2001 eruption 17 july no further injection had taken place during this period until september 2001 providing a possible reason for the quick exhaustion of the eruption in view of this we suggest that the sampled emissions are a powerful geochemical tool to investigate the etna s plumbing system and its magma dynamics as well as the development of eruptive events

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

multidisciplinary investigation on a lava fountain preceding a flank eruption the 10 may 2008 etna case a multidisciplinary approach integrating a wide data set ranging from bulk rock compositions of the erupted products to volcanic tremor long period events and tilt and gravity signals is used to investigate the source depth and magma dynamics of the 10 may 2008 lava fountain at southeast crater sec of mount etna the investigation was undertaken in the framework of the previous 2007 explosive activity as well as the subsequent effusive eruption beginning 13 may 2008 and lasting up to july 2009 all the data concur in indicating that the 10 may lava fountain was generated by the fragmentation of a foam layer trapped at the top of a shallow reservoir about 1500 1700 m below the summit of sec the shift from the episodic strombolian lava fountain activity occurring in 2007 at sec to the more powerful 10 may 2008 lava fountain is explained by the intrusion of a new more primitive magma into the shallow reservoir data also indicate that an attempted magma intrusion east of the summit area occurred during the 10 may fire fountain this event caused the fracturing and weakening of the surrounding rocks and created a preferential pathway for the penetration of the magma that only 3 days later started to feed the 2008 2009 effusive eruption

lava fountains during the episodic eruption of south east crater mt etna 2000 insights into magma gas dynamics within the shallow volcano plumbing system 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

a relation between lava discharge rate thermal insulation and flow area set using lidar data 1 a simple linear relation can be used to link time averaged discharge rate tadr and lava flow area a the relation applies to given insulation conditions as described by the characteristic flow surface temperature te and will vary from case to case depending on rheological and topographic influences on flow spreading most flows have insulation conditions that change through time modifying the relationship between tadr and area as insulation conditions evolve using lidar data we can define tadr the flow area that the discharge feeds and te allowing generation of a case specific relation to convert satellite data derived flow areas to tadr for etna s 2006 lava flow field we obtain a relation whereby tadr 5 6 10 6 a for well insulated conditions te 100 c and tadr 1 5 10 4 a for poorly insulated conditions te 600 c

patterns in the recent 2007 2008 activity of mount etna volcano investigated by integrated geophysical and geochemical observations 1 seismic deformation and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment in spite of their wide use there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques here we combine seismic volcanic tremor and long period seismicity deformation gps and geochemical volcanic gas plume co2 so2 ratios measurements in an attempt to interpret trends in the recent 2007 2008 activity of etna volcano we show that each eruptive episode occurring at the southeast crater sec was preceded by a cyclic phase of increase decrease of plume co2 so2 ratios and by inflation of the volcano s summit captured by the gps network these observations are interpreted as reflecting the persistent supply of co2 rich gas bubbles and eventually more primitive magmas to a shallow depth of 1 2 8 km asl magma storage zone below the volcano s central craters ccs overpressuring of the resident magma stored in the upper ccs conduit triggers further magma ascent and finally eruption at sec a process which we capture as an abrupt increase in tremor amplitude an upward 2800 m asl and eastward migration of the source location of seismic tremor and a rapid contraction of the volcano s summit resumption of volcanic activity at sec was also systematically anticipated by declining plume co2 so2 ratios consistent with magma degassing being diverted from the central conduit area toward sec

application of modflow for simulating groundwater flow in the trifilia karst aquifer greece karst aquifers can have a complex flow as a result of the formation of large conduits from dissolution features as a result a three dimensional finite difference groundwater flow model equivalent porous media may not apply as the dual porosity nature of karst features and the effects of turbulent flow cannot be directly simulated statistical analysis of karst hydrographs of the trifilia aquifer in greece showed the existence of a slightly karstified mass with high primary porosity that regulates the flow an equivalent porous media model was developed to simulate the trifilia karst aquifer using modflow steady state and transient state calibration gave encouraging results for the equivalent porous media approach which does not consider pipe flow or turbulence detailed hydrogeological research conducted in the area helped define the aquifer hydraulic conductivity zones and extent and flux to from the aquifer only hydraulic conductivity and specific yield were adjusted during calibration as the flux to from the system was considered known and applied as boundary conditions small mean absolute and rms piezometric head error of the model under both steady and transient state conditions were achieved

impulsive tilt variations on mount etna volcano 1990 1993 abstract this study was focussed on the analysis of the fast ground deformations impulsive anomalies recorded at the mt etna tilt array from 1990 to 1993 a period that preceded accompanied and followed the 1991 1993 eruption these fast deformations were recorded as transient anomalies ranging from a few hours to days 1 2 observed contemporaneously at several tilt stations and characterized by variations ranging from one to tens of microradians the signals evidenced volcanic dynamics characterized by tilt anomalies during the non eruptive periods 1990 1993 the pre eruptive period november december 1991 the beginning of the eruption 14 15 december 1991 and the eruption course 1992 in particular pre seismic co eruptive and co seismic anomalies were recorded during the pre eruptive period and the eruption onset in these cases interpretations of the phenomena and comparison to modelling studies are provided furthermore tilt variations affecting the global volcanic edifice were also observed one year before the eruption when they were followed by seismicity and during the eruption course without seismicity we interpreted this last class of tilt variations as due to the push of the magma uprising along the main nnw sse structure crossing mt etna

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