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

antarctic cryogenic sediments biotic and inorganic facies of ice shelf and marine based ice sheet environments abstract cryogenic sediments defined as marine deposits that form in association with ice icebergs sea ice ice shelves or marine based ice sheets are widespread in high latitude regions existing models for cryogenic depositional processes are of limited utility because of 1 lack of direct observational data 2 reliance on older land exposed sections from which inferential conclusions have been drawn 3 employment of inadequate glaciologic and oceanographic concepts and 4 failure to incorporate adequately information on the biotic content of these deposits as a first step toward developing a synthetic model for cryogenic deposition we relate glaciologic sedimentologic and biotic processes of the modern ice shelf and marine based ice sheet environments using data from antarctic continental shelves the principal deposit beneath grounded marine based ice sheets is lodgement till which often contains reworked and fragmented fossil material this till is identical in all important sedimentologic respects with terrestrial lodgement deposits marine lodgement tills commonly form geographically extensive sheets which are restricted to continental shelf sites and which may be differentiated from other cryogenic deposits by their high degree of compaction and reworked fossils waterlain till may form beneath grounded ice in areas where debris melting out of the glacier sole falls through a thin water layer up to a few m between the ice and its bed waterlain till usually lacks fossil material unless the source material for the subglacial debris is fossiliferous and is less compact than lodgement till deposition beneath large polar ice shelves e g ross filchner ronne is largely restricted to a zone probably km in width near the grounding line in this zone a complex of primary and secondary cryogenic deposits including waterlain till ice shelf rafted detritus isrd flow till slumps etc is likely to interfinger processes controlling this deposition include local basal conditions of the ice sheet and ice shelf freezing or melting presence or absence of subglacial outflow marine currents and tidal action sediment supply long and short term grounding line movement sea floor topography and water depth deposition of isrd is limited elsewhere beneath these large ice shelves because high surface accumulation rates cause downward particle paths for ice and debris thus most debris is released soon after passing the grounding line biotic activity beneath ice shelves declines rapidly in diversity and abundance between the calving margin and grounding line deposition rates seaward of the calving margin are much higher than beneath the large ice shelves here icebergs derived from outlet glaciers and ice streams that terminate directly in the sea may carry significant loads of subglacial englacial or superglacial debris which is released by a variety of mechanisms as the icebergs melt this ice rafted detritus mixes with biotic material from planktonic organisms as it falls through the water column to form compound ibrd if currents are present in the water column or at the seafloor sorting may occur to form residual ibrd on shallow banks grounded icebergs carrying subglacial debris may melt in situ forming iceberg till and iceberg ploughing of sediment may form iceberg turbate both these deposits may be difficult to distinguish from lodgement till but both are restricted to areas with modern water depths less than 450 m

three dimensional effects causing artifacts in two dimensional cross borehole electrical imaging summary cross borehole electrical resistance tomography ert experiments utilize downhole electrodes typically placed in a borehole filled with material of contrasting resistivity to the host rock the circular geometry of the boreholes is three dimensional and inversion routines are typically two dimensional because of the resistivity contrast artifacts in the form of borehole inversion effects develop in the resistivity images other 3d effects resulting in inversion artifacts are shadow effects caused by use of a 2d code to invert data from a 3d body located outside the image plane in both cases the inversion model misrepresents the spatial change in voltages as a corresponding spatial change in resistivity borehole inversion effects and shadow effects result as the forward solver attempts to resolve the discrepancy in the voltages for numerous electrode pairs into a meaningful resistivity distribution borehole inversion effects are shown to be related to the resistivity contrast between the borehole fill and the host medium and to borehole diameter borehole inversion effects do not materialize with small diameter boreholes e g 0 1 m when the fill resistivity contrast is one order of magnitude or less however a borehole fill resistivity contrast of two orders of magnitude causes artifacts in the form of sheaths near the boreholes and a conductive artifact between the boreholes larger diameter borehole e g 0 2 m induce significant borehole inversion effects with as little as one order of magnitude fill resistivity contrast the general resistivity patterns are similar for the borehole inversion effects however the artifacts are amplified as resistivity contrast and or borehole diameter increase these results are significant because borehole inversion effects may mask a target heterogeneity or an artifact may be confused for an anomaly resulting in improper actions for site characterizations or remediation strategies suggestions of best practices for experimental design to prevent or minimize borehole inversion effects include minimizing borehole diameter minimizing borehole fill resistivity contrast measuring and inputting the resistivity of the borehole fill water into the model and inverting changes in resistivity for time lapse ert data shadow effects are shown to be related directly to the distance of the target heterogeneity out of the image plane our results show that shadow effects become insignificant when the target is between 3 and 5 m outside the 10 m wide image plane because the size of the target and resistivity contrast of the target to the host rock are site specific variables the actual distance at which shadow effects become insignificant will vary from site to site to reduce misinterpretations by shadow effects reduce the dipole length of the four electrode measurements and supplement data from other well pairs and or other methods

volatile induced magma differentiation in the plumbing system of mt etna volcano italy evidence from glass in tephra of the 2001 eruption mount etna volcano was shaken during the summer 2001 by one of the most singular eruptive episodes of the last centuries for about 3 weeks several eruptive fractures developed emitting lava flows and tephra that significantly modified the landscape of the southern flank of the volcano this event stimulated the attention of the scientific community especially for the simultaneous emission of petrologically distinct magmas recognized as coming from different segments of the plumbing system a stratigraphically controlled sampling of tephra layers was performed at the most active vents of the eruption in particular at the 2 100 m cal and at the 2 550 m lag scoria cones detailed scanning electron microscope and energy dispersive x ray spectrometer sem eds analyses performed on glasses found in tephra and comparison with lava whole rock compositions indicate an anomalous increase in ti fe p and particularly of k and cl in the upper layers of the lag sequence mass balance and thermodynamic calculations have shown that this enrichment cannot be accounted for by classical differentiation processes such as crystal fractionation and magma mixing the analysis of petrological features of the magmas involved in the event integrated with the volcanological evolution has evidenced the role played by volatiles in controlling the magmatic evolution within the crustal portion of the plumbing system volatiles constituted of h2o co2 and cl complexes originated from a deeply seated magma body dbm their upward migration occurred through a fracture network possibly developed by the seismic swarms during the period preceding the event in the upper portion of the plumbing system a shallower residing magma body abt had chemical and physical conditions to receive migrating volatiles which hence dissolved the mobilized elements producing the observed selective enrichment this volatile induced differentiation involved exclusively the lowest erupted portion of the abt magma due to the low velocity of volatiles diffusion within a crystallizing magma body and or to the short time between volatiles migration and the onset of the eruption furthermore the increased amount of volatiles in this level of the chamber strongly affected the eruptive behavior in fact the emission of these products at the lag vent towards the end of the eruption modified the eruptive style from classical strombolian to strongly explosive

link between major flank slip and 2002 2003 eruption at mt etna italy 1 the 2002 2003 etna eruption is studied through earthquake distributions and surface fracturing in september 2002 earthquake induced surface rupture sinistral offset 0 48 m occurred along the e w striking pernicana fault pf on the ne flank in late october a flank eruption accompanied further 0 77 m surface rupturing reaching a total sinistral offset of 1 25 m the deformation then propagated for 18 km eastwards to the coastline sinistral offset 0 03 m and southwards along the nw se striking timpe dextral offset 0 04 m and later trecastagni faults dextral offset 0 035 m seismicity 4 km bsl on the e flank accompanied surface fracturing fault plane solutions indicate an overall ese wnw extension direction consistent with ese slip of the e flank also revealed by ground fractures a three stage model of flank slip is proposed inception september earthquake climax accelerated slip and eruption and propagation e and s migration of the deformation

saline tracer visualized with three dimensional electrical resistivity tomography field scale spatial moment analysis 1 cross well electrical resistivity tomography ert was used to monitor the migration of a saline tracer in a two well pumping injection experiment conducted at the massachusetts military reservation in cape cod massachusetts after injecting 2200 mg l of sodium chloride for 9 hours ert data sets were collected from four wells every 6 hours for 20 days more than 180 000 resistance measurements were collected during the tracer test each ert data set was inverted to produce a sequence of 3 d snapshot maps that track the plume in addition to the ert experiment a pumping test and an infiltration test were conducted to estimate horizontal and vertical hydraulic conductivity values using modified moment analysis of the electrical conductivity tomograms the mass center of mass and spatial variance of the imaged tracer plume were estimated although the tomograms provide valuable insights into field scale tracer migration behavior and aquifer heterogeneity standard tomographic inversion and application of archie s law to convert electrical conductivities to solute concentration results in underestimation of tracer mass such underestimation is attributed to 1 reduced measurement sensitivity to electrical conductivity values with distance from the electrodes and 2 spatial smoothing regularization from tomographic inversion the center of mass estimated from the ert inversions coincided with that given by migration of the tracer plume using 3 d advective dispersion simulation the 3 d plumes seen using ert exhibit greater apparent dispersion than the simulated plumes and greater temporal spreading than observed in field data of concentration breakthrough at the pumping well

mid cenozoic record of glaciation and sea level change on the margin of the victoria land basin antarctica the mssts 1 drill hole in western mcmurdo sound provides the earliest physical record thus far for antarctic cenozoic glaciation the hole penetrated 227 m of muddy marine glacial sediment containing scattered pebble and cobble size clasts including seven diamictite beds deposited from grounded ice during glacial advances a diatom based chronology refined by paleomagnetic stratigraphy for the interval below 116 m subbottom indicates sediment accumulation from 29 ma to about 24 ma sediment texture and paleoecology of diatoms and foraminifers indicate nearshore sedimentation on a wave dominated shelf the oldest strata record a significant shallowing of water depth culminating in ice grounding at around 28 ma and a deepening at 25 ma that may be glacioeustatic

assessing subglacial processes from diatom fragmentation patterns reconstructing the size and glacial style of past ice sheet advances requires interpreting complex glacial sedimentary facies we use diatoms a major component of antarctic continental shelf deposits to infer the physical conditions under which these deposits were emplaced the degree of diatom fragmentation and the presence of diatoms of varying stratigraphic age in glacial sediments provide means to qualitatively gauge glacial mixing and transport here we report an experimentally calibrated index of diatom fragmentation that provides a simple but objective method of assessing the degree of subshearing imparted on marine glacial sedimentary deposits by using a ring shear device to subject diatomaceous sediment to stresses comparable to those beneath the ross ice streams we quantitatively assess patterns of diatom comminution resulting from compaction and from progressive shear stress elongate pennate diatoms are found to break disproportionately to discoid centric diatoms when subjected to shear stress thus a simple ratio of unbroken centric to pennate diatoms provides a reliable gauge of past shearing comparison of ring shear results with a suite of previously analyzed sediments that represent a variety of glacial glacial marine and hemipelagic settings of the ross sea and subglacial ross embayment demonstrates that this index can be employed for estimating relative subglacial stresses in this setting

cenozoic marine sedimentation and ice volume variation on the east antarctic craton recycled cretaceous and cenozoic marine microfossils have been recovered from samples of the pliocene sinus formation samples were collected from outcrops in the reedy beardmore and ferrar glacier areas of the transantarctic mountains between lat 77 and 86 s the glaciogene sediments contained diatoms foraminifera calcareous nannoplankton silicoflagellates radiolarians sponge spicules palynomorphs and ostracodes of late cretaceous paleocene eocene late oligocene late miocene and pliocene age this suggests the presence of open marine basins on the east antarctic craton during late mesozoic and cenozoic time the apparent absence of early oligocene and early through middle and earliest late miocene assemblages suggests either that marine regression exposed the basin floors or that ice filled the basins during these times the high elevation setting of sirius formation outcrops suggests one of two hypotheses for their origin 1 they are in situ pliocene glaciomarine deposits that were uplifted 1 750 2 500 m with the transantarctic mountains to their present elevation 2 the sirius formation deposits are a mixture of derived sediments stripped from sub ice intracratonic basins and subsequently redeposited by ice flowing up the inland slope of the transantarctic mountains we favor the second hypothesis with transport to sites sometime within the past 3 m y

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

early pliocene marine sediments coastline and climate of east antarctica we record the first onshore late tertiary fossiliferous marine deposit from the 8000 km long coastline of east antarctica glaciomarine sediments containing abundant diatoms and molluscs were deposited in shallow waters off an open coast during the early pliocene 4 5 3 5 ma and are now exposed less than 15 m above sea level on marine plain in the vestfold hills lat 68 359s long 78 009e marine diatoms suggest early pliocene as the most probable age of the sediments fossil sand wedges show that the deposit was above sea level at least briefly before it was covered with water and subsequently capped with glaciomarine till the coastline at the time of deposition of the marine sediments is inferred to have been close to but farther inland than that of today the ice margin may have been 50 km farther inland considerably reducing the ice volume of antarctica climate at the time of deposition was interglacial and perhaps warmer than the present

the morphology of ice streams a b and c west antarctica and their environs airborne radar soundings of the ice sheet surface made in 1984 1985 together with elevations measured by oversnow traverses between 1957 and 1964 have been used to produce a surface elevation map of ice streams a b and c and much of the region around them the flight positions and elevations were tied to many ground control stations whose positions in three dimensions were fixed by satellite tracking ice thicknesses were also measured along the flight lines but have not yet been mapped the surfaces of active ice streams a and b exhibit a longitudinal ridgetrough topography of uncertain origin prominent surface valleys are associated with most but not all of their marginal shear zones there is a deep subglacial trough beneath the grid northeastern side of ice stream a that connects to the subglacial trough beneath reedy glacier the boundary between ice streams bl and b2 the two tributaries of ice stream b persists as a suture zone for 250 km downstream from their merger ice stream bl overlies a relatively deep subglacial trough that continued under the corresponding part of ice stream b until it disappears close to the grounding line between ice streams bl and b2 there is a complex zone containing several regions of undisturbed ice separated by bands of disturbed ice which suggest to us that rafts of ice are being incorporated into the ice streams the previously reported negative mass balance for the drainage system of ice stream b may arise from the expansion of the ice stream into the interior of the west antarctic ice sheet crevasse bands at some places on ridge ab together with high glacial velocities reported elsewhere also suggest this expansion close to the ross ice shelf ice stream b widens into a nearly flat area where the mean surface slope is only 3 5 10 4 and the surface elevations are only a few tens of meters above hydrostatic equilibrium inactive ice stream c differs from active ice streams a and b in surficial and basal characteristics no elongated ridges and troughs are observed instead the ice stream surface exhibits several terraces including some maxima and minima in elevation radar sounding reveals areas where basal echoes are strong and steady indicating subglacial water alternating with areas of weaker echoes with short fading lengths calculations indicate that the strong reflections require a water layer at least several centimeters to several meters thick depending on the electrical conductivity of the water due to reversals in the surface slope the hydrologic potential gradient changes sign several times along ice stream c which implies that subglacial water should collect in some locations

sedimentation beneath ice shelves the view from ice stream b abstract ice shelf development is favored by rapid flow of cold ice from outlet glaciers or ice streams into protected embayments with localized high spots basal melting of ice shelves is rapid near the ice front and may occur near the grounding line ice from outlet glaciers may contain significant englacial debris that is deposited as a dropstone diamicton in regions of basal melting englacial debris is sparse or absent in ice streams evidence from ice stream b draining into the ross ice shelf of west antarctica suggests that the rapid ice velocity arises from deformation of a several meter thick water saturated basal till layer that is eroding an unconformity on sediments beneath and that has deposited a till delta tens of meters thick and tens of kilometers long at the grounding line sea level fall would cause conveyor belt recycling of this till delta and grounding line advance across the ross sea to the edge of the continental shelf forming an ice sheet with a low ice stream profile resting on a several meter thick deforming till layer eroding an unconformity the modern ross sea is characterized by a regional unconformity overlain by a diamicton of probable latest pliocene pleistocene age measuring several meters to tens of meters thick we hypothesize that this diamicton is a deformed glacial till and that the ross sea sediments record one or more expansions of the till lubricated west antarctic ice sheet to the edge of the continental shelf

new insights into magma dynamics during last two eruptions of mount etna as inferred by geochemical monitoring from 2002 to 2005 two distinct eruptive events characterize the volcanic activity at mount etna during the 2002 to 2005 period we identified signals of magma ascent preceding these eruptions by geochemical monitoring of both chemical composition and he isotope ratio of gas emissions from five locations in the peripheral area of the volcano the geochemical signals are interpreted using the models proposed by caracausi et al 2003a 2003b and allow identification of episodes of magma ascent and estimation of the pressures of degassing magma as observed for the 2001 eruption caracausi et al 2003b magma ascent probably triggered the onset of the 2002 2003 eruption and minor events of magma ascent were observed between may and december 2003 in contrast to the previous two eruptions the 2004 2005 eruption was not preceded by significant geochemical signals of volcanic unrest suggesting that this eruption was mainly triggered by the failure of the upper portion of the volcanic edifice under the magmatic hydrostatic pressure in the conduits high 3he 4he ratio revealed new volatile rich magma accumulation the 2002 2003 eruption was preceded by a much shorter period of new magma accumulation from deep levels of the feeding system few minor signals of magma migration were detected at some of the sites during the months preceding the 2004 2005 eruption suggesting that the degassed 3he depleted magma resident in the volcanic conduits was not replaced by new volatile rich magma this is in agreement with the lack of explosive activity during the 2004 2005 eruption and with petrologic observations that the parent magma probably erupted in 2000 and 2001 new geochemical signals of magma ascent from the deep reservoir have been identified since june 2005 indicating that the volcanic activity of mount etna is evolving toward new pre eruptive conditions

direct current and self potential monitoring of an evolving plume in partially saturated fractured rock abstract hole surface and hole hole mise a la masse malm measurements and surface self potential sp measurements were taken over a 173 day period during an 8 well radial injection tracer experiment in partially saturated fractured columbia river basalt a potassium chloride tracer stream was injected into the fractured basalt and was energized directly for the malm experiments the constant concentration tracer solution was injected for 76 days above a perched water table at an average rate of 10 07 l day tracer injection was followed by a 34 day period of tap water injection and a 63 day drainage period the associated changes in potential distributions and sp s over time indicate that an asymmetrical vadose zone plume evolved in the fractured basalt hole surface and sp measurements were used to track the lateral evolution of the tracer plume however there was some noise and variability in the sp data the hole hole measurements helped delineate the depth of preferential tracer migration in the fractured basalt

borehole cylindrical noise during hole surface and hole hole resistivity measurements drilled boreholes generally are the only feasible means to access the subsurface for the emplacement of downhole electrodes for most hole hole and hole surface resistivity experiments however the very existence of the borehole itself creates the potential for significant noise due to the inevitable conductivity contrast that develops between the borehole walls and the formation borehole cylindrical noise develops whenever a current source is placed in a drilled borehole borehole geometries may range from nearly perfect cylinders to highly irregular rugose holes in consolidated rock to relatively minor collapsed disturbed zones in caving sediments boreholes in non caving formations generally are filled with artificial conductive materials to afford crucial electrical continuity between downhole electrodes and the borehole walls filled boreholes form cylindrically shaped heterogeneities that create significant noise due to preferential current flow up and down the conductive columns selected conditions are simulated with a finite difference model to illustrate the significance of borehole cylindrical noise on hole hole and hole surface mise a la masse electrical potentials near a current electrode mise a la masse electrical potentials measured during a field tracer experiment also are presented these measurements are used to illustrate significant errors may develop in the interpretation of apparent resistivity estimates out to a distance of several meters from the current source if borehole cylindrical noise is not recognized and accounted for in the analysis of electrical potential data

relationship between the flank sliding of the south east crater mt etna italy and the paroxysmal event of november 16 2006 over the last 2 years the south east crater sec at mt etna italy has been characterised by the intermittent emission of lava flows often accompanied by paroxysmal episodes with violent strombolian activity and or lava fountains one of the most intense and intriguing episodes occurred on november 16 2006 during strombolian and effusive activity from the very top of the sec at the eastern base of the crater a violent and short lasting outburst generated a 300 m high eruptive curtain of finely fragmented magma and steam which collapsed in a few seconds giving rise to a small but significant pyroclastic flow the paroxysm was preceded by progressive sliding of the eastern flank of the sec edifice which led to the formation of a large niche previously published models explain the outburst as due to rapid vaporisation of water contained in sediments on contact with hot lava flowing along the flank of the sec or alternatively to gravitational collapse of a destabilised portion of the eastern flank of the crater however several lines of evidence suggest that these models do not adequately explain the paroxysm which we propose was associated with the explosive emission of magma during the rapid opening of an ese wnw oriented fracture at the eastern base of the sec moreover geochemical data of the products associated with this episode show that they are the most primitive and gas rich among those erupted during the entire 2006 period we suggest that the paroxysm of november 16 2006 which occurred at base of the sec was a magma outburst due to rapid ground fracturing related to a drop in confining pressure upon the underlying dyke consequent to the sliding of the eastern flank of the sec cone specifically the unloaded shallow portion of the feeding dyke did not restrain the arrival of a new batch of gas rich magma which worked its way out by fracturing the base of the niche at its weakest point this paroxysm appears significant because it reveals the potential development of syn eruptive dynamics acting directly on the uppermost portion of the plumbing system which is able to generate pyroclastic flows even on basaltic volcanoes such as mount etna

the 2004 2005 etna eruption implications for flank deformation and structural behaviour of the volcano the development of the 2004 2005 eruption at etna italy is investigated by means of field surveys to define the current structural state of the volcano in 2004 2005 a fracture swarm associated with three effusive vents propagated downslope from the se summit crater towards the se such a scenario is commonly observed at etna as a pressure increase within the central conduits induces the lateral propagation of most of the dikes downslope nevertheless some unusual features of this eruption slower propagation of fractures lack of explosive activity and seismicity oblique shear along the fractures suggest a more complex triggering mechanism a detailed review of the recent activity at etna enables us to better define this possible mechanism in fact the nw se trending fractures formed in 2004 2005 constitute the southeastern continuation of a n s trending fracture system which started to develop in early 1998 to the east of the summit craters the overall 1998 2005 deformation pattern therefore forms an arcuate feature whose geometry and kinematics are consistent with the head of a shallow flank deformation on the e summit of etna similar deformation patterns have also been observed in analogue models of deforming volcanic cones in this framework the 2004 2005 eruption was possibly induced by a dike resulting from the intersection of this incipient fracture system with the se crater a significant acceleration of this flank deformation may be induced by any magmatic involvement the central conduit of the volcano is presently open constantly buffering any increase in magmatic pressure and any hazardous consequence can be expected to be limited a more hazardous scenario may be considered with a partial or total closing of the central conduit in this case magmatic overpressure within the central conduit may enhance the collapse of the upper eastern flank triggering an explosive eruption associated with a landslide reaching the eastern lower slope of the volcano

discrete monitoring of chemical parameters in ground waters of mt etna volcano 2000 2006 abstract three sites of groundwater captation on mt etna volcano namely currone ilice and pavone were sampled systematically for six years from 2000 to 2006 for the determination of the major ionic composition of water the monitored sites were chosen among those most representative of the geochemical characteristics of the groundwater systems of the volcano the period studied was characterized by several strong eruptions of mt etna both at its summit craters and along its flanks the overall composition of the waters sampled at currone and ilice falls in the group of bicarbonate alkaline earth compositions whereas those from pavone show a bicarbonate alkaline composition in all sites however some samples show input of chlorine sulfate alkaline waters likely due to interaction between fresh groundwater and either acidic waters from so2 polluted rainwater more evident at pavone or geothermal brines more evident at currone significant temporal variations affected in a more or less marked way all of the parameters measured at the three sites basic statistical correlations among the parameters at each site allowed to discover a general coherent temporal behavior of all major ions dissolved in mt etna s ground waters factor analysis allowed showing up to three main groups of parameters with similar temporal behavior depending on the site a first group was explained by interaction between volcanic ground waters and geothermal fluids a second group was related with leaching of the host volcanic rocks by co2 rich volcanic water a third group was explained as due to input of plume so2 derived sulfate through water recharge using normal probability plots for each parameter at the three sites it was possible to reveal different geochemical populations explained as background anomalous values and possibly outliers plotting the temporal patterns of all the monitored parameters versus the concurrent eruptive episodes at mt etna we discovered significant correlations that although with different intensity and rate depending on the parameter and on the site highlighted several geochemical processes induced by interaction between cold groundwater and magmatic hydrothermal fluids mostly following changes in the ground permeability of the volcanic pile these processes seemed to be enhanced during periods of shallow magma accumulation inside of the volcano that preceded summit or flank eruptions occurred at mt etna during the monitored period

long term record of co2 degassing along mt etna s flanks and its relationship with magma dynamics and eastern flank instability a record of soil co2 flux data on the lower flanks of mt etna measured from 1989 to 2008 is discussed in the framework of multidisciplinary observations including seismicity ground deformations and flank instability a huge increase in soil co2 fluxes appears to be related to the dynamics of magma ascent in the upper portions of the volcano 0 3 km and the intrusion of dykes along the southern rift as mainly observed before the 1991 93 eruption even after the 1991 93 eruption the recharge of the shallow central reservoir was accompanied by a long term increase in soil co2 degassing mainly in the southwestern area the 2001 eruption marked dramatic changes in the areal distribution of seismicity the deformation pattern and the soil co2 degassing indeed while the soil co2 degassing showed background values in the southwestern area it progressively increased in the eastern sector and along the pernicana fault this has been related to the marked sliding of the eastern flank since the 2002 03 eruption and the associated seismicity this study provides evidence that the extent of soil co2 degassing on the lower flanks of mt etna is controlled by 1 the volume of involved magma 2 the intrusion of dykes in the upper parts of the volcano and 3 fault movement and seismicity this implies that different degassing structures must be monitored simultaneously when attempting to understand the behavior of the volcano as a whole

geochemical pattern classification of recent volcanic products from mt etna italy based on kohonen maps and fuzzy clustering we present the application of a classification method based on kohonen maps and fuzzy clustering to geochemical analyses of volcanic products erupted on mt etna from 1995 to 2005 based on 13 major and trace elements the classification allows a new way to visualize distinct compositional features of magma both considering long period as well as single eruptive events such as in 2001 and 2002 03 flank eruptions products of the various vents do not necessarily form homogeneous groups but show clear trends of chemical evolution with time using a convenient color code the graphical visualization of the results in just a single picture allows the rapid identification of the compositional features of each sample and their comparison with all the products analyzed in the 10 year long time span this single picture accounts for the mutual interactions of the 13 components avoiding shortcomings of classical low dimensional plots where components relevant for the discrimination have to be found in a priori study of many diagrams on the basis of the synoptic information provided by pattern classification we identify links between the products of different eruptive vents which deliver a reliable picture of a multifaceted plumbing system in agreement with geochemical and geophysical evidence reported in literature the analysis of the 13 dimensional data set using the kohonen maps and fuzzy clustering simultaneously turned out to be straightforward and easy accordingly the results of this application will be useful also as a contextual data set for new data in future ongoing eruptive episodes

low pressure crystallization paths of h2o saturated basaltic hawaiitic melts from mt etna implications for open system degassing of basaltic volcanoes melt inclusions indicate that the basaltic hawaiitic magmas from mt etna sicily contained up to 2 3 wt h2o dissolved in the melt prior to eruption the effect of h2o degassing during magma ascent has been experimentally constrained between 1135 and 1009 c for ph2o ptotal varying from 800 to 270 bars the starting material was a primitive hawaiitic lava sample mgo 7 1 wt representative of the less evolved lava emitted at mt etna experiments were conducted in tzm pressure vessels with ag70pd30 capsules in order to minimize the feo loss at temperatures of 1135 1090 c ph2o 800 bars with ninio and fmq buffers olivine fo83 80 is the liquidus phase in equilibrium with a residual hawaiitic melt mg 0 60 0 57 cao al2o3 0 82 salitic pyroxene begins to crystallize at 1075 c plagioclase at 1025 c and at 1009 c the magma is 33 5 crystallized with olivine ca rich pyroxene and plagioclase 16 60 24 at ph2o 270 bars fmq buffer olivine fo79 3 80 and salitic pyroxene are the main liquidus phases between 1100 and 1090 c they are in equilibrium with hawaiitic melts mg 0 51 cao al2o3 0 73 at 1070 c the experimental charges are highly crystallized 51 5 with olivine fo70 salite and plagioclase an78 4 76 3 in 14 44 42 relative proportions increasing the water content of hawaiitic basaltic magmas expands the stability field of the olivine relative to the other phases lowers the crystallization temperatures of pyroxene and plagioclase and results in the development of a more an rich plagioclase when compared to the natural samples these results support a model of early and moderate crystallization of olivine from etnean primitive hawaiitic magmas containing close to 2 5 wt h2o with nno oxygen buffering conditions at low pressure ph2o ptotal we propose a model of crystallization driven by decompression and water degassing during the emplacement of magma in the volcanic pile itself and possibly concomitant with the opening of fractures

interpretation of sediment cores from the ross ice shelf site j 9 antarctica stratigraphical interpretations of sediments beneath the ross ice shelf antarctica are derived from 58 short gravity cores up to 1 22 m in length taken by webb and brady through an ice access hole at the ross ice shelf risp site j 9 82 22 s 168 38 w during the austral summers of 1977 and 1978 some scientific reports on microfossil groups of diatoms1 2 foraminifera3 and silicoflagellates4 have interpreted the sedimentary succession as in situ and of miocene age webb5 has also reported reworked clasts of cretaceous foraminifera brady and martin2 suggested that the pollen assemblage within the cores similar to a reported oligocene flora6 may have reflected a remnant of this flora living in the miocene but wrenn7 has shown that these pollen have probably been reworked however kellogg and kellogg s8 diatom based pleistocene age determinations for sediment exposed on the sea floor at site j9 relies on misquoted data from published literature and on misinterpreted taxonomy evidence is presented here that supports an earlier proposal that miocene sediments crop out on the present sea floor

elemental and isotope covariation of noble gases in mineral phases from etnean volcanics erupted during 2001 2005 and genetic relation with peripheral gas discharges abstract during 2001 2005 mount etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents which involved at least two types of magma with different degrees of evolution we investigated the ratios and abundances for noble gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products we confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases while pyroxene can suffer diffusive he loss both the minerals also experience noble gas air contamination after eruption helium isotopes of the products genetically linked to the two different magmas fall in the isotopic range typical of the etnean volcanism this result is compatible with the metasomatic process that the etnean mantle is undergoing by fluids from the ionian slab during the last ten kyr as previously inferred by isotope and trace element geochemistry significant differences were also observed among olivines of the same parental magma that erupted throughout 2001 2005 with 3he 4he ratios moving from about 7 0 ra in 2001 volcanites to 6 6 ra in 2004 2005 products changes in he abundances and isotope ratios were attributed to variations in protracted degassing of the same magma bodies from the 2001 to the 2004 2005 events with the latter lacking any contribution of undegassed magma the decrease in 3he 4he is similar to that found from measurements carried out every fifteen days during the same period in gases discharged at the periphery of the volcano to our knowledge this is the first time that such a comparison has been performed so in detail and provides strong evidence of the real time feeding of peripheral emissions by magmatic degassing

electrical resistivity imaging of hydrologic flow through surface coal mine valley fills with comparison to other landforms surface coal mining has altered land cover near surface geologic structure and hydrologic processes of large areas in central appalachia usa these alterations are associated with changes in water quality such as elevated total dissolved solids which is usually measured via its surrogate specific conductance sc the sc of valley fill effluent streams is a function of fill construction methods materials and age yet hydrologic studies that relate these variables to water quality are sparse due to the difficulty of conducting traditional hydrologic studies in mined landscapes we used electrical resistivity imaging eri to visualize the subsurface geologic structure and hydrologic flow paths within a valley fill eri is a noninvasive geophysical technique that maps spatiotemporal changes in resistivity of the subsurface we paired eri with artificial rainfall experiments to track infiltrated water as it moved through the valley fill results indicate that eri can be used to identify subsurface geologic structure and track advancing wetting fronts or preferential flow paths our results suggest that the upper portion of the fill contains significant fines whereas the deeper profile is primarily large rocks and void spaces water tended to pond on the surface of compacted areas until it reached preferential flow paths where it appeared to infiltrate quickly down to 15 m depth in 75 min eri applications can improve understanding of how fill construction techniques influence subsurface water movement and in turn may aid in the development of valley fill construction methods to reduce water quality effects

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

evidence for a recent change in the shallow plumbing system of mt etna italy gas geochemistry and structural data during 2001 2005 abstract we analyzed crater so 2 fluxes from mt etna together with soil co 2 effluxes from the volcano s flanks in the period from 2001 to 2005 between the 2001 and 2002 2003 eruptions persistently low values of both parameters suggest that no new gas rich magma was accumulating at shallow depth 2 sin eruptive fluxes during the two eruptions indicated sudden decompression of an un degassed magma rising along newly formed eccentric conduits in november 2003 soil co 2 data indicate migration of gas rich magma from deep 10 km to shallow 2 fluxes a similar behavior was observed also during and after the following 2004 2005 eruption this degassing style matches a period of increased structural instability of the volcanic edifice caused by acceleration of spreading that affected both its eastern and southern flanks spreading could have triggered progressively deeper depressurization in the central conduit inducing release of the more soluble gas so 2 first and then of co 2 contrary to what was observed before the 2001 eruption this suggests that the edifice has depressurized promoting ascent of fresh magma and increasing permeability favouring release of co 2 flux by integrating geochemical and structural data previous degassing models developed at mt etna have been updated to advance the understanding of eruptive events that occurred in recent years

organic carbon in sediments underlying the ross ice shelf abstract percentages mean 0 36 and 13c values mean 25 4 vs pdb for organic carbon in 13 samples in the top meter of sediments of miocene age underlying the ross ice shelf at site j9 indicate organic carbon deposition during the miocene much like that of recent time i e a mixture of organic carbon rich polar diatom ooze with 13c signature of about 27 and older kerogen contained in indurated shale fragments with percent and 13c of about 0 1 and 22 respectively

2001 flank eruption of the alkali and volatile rich primitive basalt responsible for mount etna s evolution in the last three decades abstract since the early 1970s enhanced eruptive activity of mount etna has been accompanied by selective geochemical changes in erupted lavas among which a gradual increase of alkalis whose origin is still debated here we provide further insight into the origin of this recent evolution based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase poor primitive basalt that was extruded during a highly explosive flank eruption in july august 2001 two types of lava were erupted simultaneously along a n s fracture system trachybasalts from the upper vents 2950 2700 m were simply drained out by fracturing of the central volcanic conduit they are identical to summit crater lavas and contain mg poor olivines fo 70 72 with evolved and volatile poor melt inclusions that represent late stage crystallisation during shallow open conduit degassing in contrast plagioclase poor basalt 80 of total extruded through the lower vents 2550 2100 m derived from lateral dyke intrusion of a more primitive and volatile rich magma across the sedimentary basement this primitive melt is best preserved in rare fo 82 4 80 5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent its high dissolved contents of h 2 o 3 4 wt co 2 0 11 to 0 41 wt s 0 32 wt cl 0 16 wt and f 0 094 wt point to its closed system ascent from 400 to 250 mpa 12 to 6 5 km depth b s l however the predominance of euhedral olivine phenocrysts with common reverse zoning cores fo 76 78 and rims fo 78 80 and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting the few preserved inclusions in these olivines indicate pre eruptive storage of that magma body at about 5 km depth b s l in coherence with seismic data we propose that the 2001 flank eruption resulted from gradual overpressuring of etna s shallow plumbing system due to the influx of volatile rich primitive basalt that may have begun several months in advance we find that this basalt is much richer in alkalis 2 0 wt k 2 o and has higher s cl 2 0 but lower cl k and cl f ratios than all pre 1970s etnean lavas 1 4 wt k 2 o s cl 1 5 as further exemplified by melt inclusions in entrained olivine xenocrysts combining these new observations with previously published data we argue that the 2001 basalt represents a new alkali rich basic end member feeding mt etna only few amount of which had previously been extruded during a 1974 peripheral eruption and more recently during brief paroxysmal summit events over the last three decades this new magma has progressively mixed with and replaced the former k poorer trachybasalts filling the plumbing system leading to extrusion of gradually more primitive and alkali richer lavas its geochemical singularities cannot result from shallow crustal contaminations instead they suggest the involvement of an alkali richer but cl poorer arc type component during recent magma genesis beneath etna

continuous tracking of volcanic tremor at mount etna italy summary using data from two dense array of short period seismometers we analyse the kinematic properties of volcanic tremor preceding and accompanying the 2004 2005 eruption of etna volcano italy results from slowness analyses indicate the action of at least two distinct sources the first dominates the pre eruptive period and is likely associated with the main plumbing system feeding the summit and southeast craters following the onset of the eruption secondary directions of wave arrival encompass the eruptive fissures located on the lower eastern flank of the southeast crater nonetheless significant energy radiation from this latter source was also occurring prior to the onset of the lava effusion likely suggesting the presence of a resident magma batch in agreement with independent petrologic and geochemical data

petrology of lavas from the 2004 2005 flank eruption of mt etna italy inferences on the dynamics of magma in the shallow plumbing system 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

cooling and crystallization of lava in open channels and the transition of pāhoehoe lava to a ā samples collected from a lava channel active at kilauea volcano during may 1997 are used to con strain rates of lava cooling and crystallization during early stages of flow lava erupted at near liquidus tem peratures f1150 7c cooled and crystallized rapidly in upper parts of the channel glass geothermometry indi cates cooling by 12 14 7c over the first 2 km of trans port at flow velocities of 1 2 m s this translates to cooling rates of 22 50 7c h cooling rates this high can be explained by radiative cooling of a well stirred flow consistent with observations of non steady flow in proximal regions of the channel crystallization of plag ioclase and pyroxene microlites occurred in response to cooling with crystallization rates of 20 50 per hour crystallization proceeded primarily by nucleation of new crystals and nucleation rates of f10 4 cm 3 s are similar to those measured in the 1984 open channel flow from mauna loa volcano there is no evidence for the large nucleation delays commonly assumed for plagioclase crystallization in basaltic melts possibly a reflection of enhanced nucleation due to stirring of the flow the transition of the flow surface morphology from pahoehoe to a aoccurred at a distance of 1 9 km from the vent at this point the flow was thermally stratified with an interior temperature of f1137 7c and crystallinity of f15 and a flow surface tempera ture of f1100 7c and crystallinity of f45 a afor mation initiated along channel margins where crust was continuously disrupted and involved tearing and clotting of the flow surface both observations suggest that the transition involved crossing of a rheological threshold we suggest this threshold to be the develop ment of a lava yield strength sufficient to prevent vis cous flow of lava at the channel margin we use this concept to propose that a aformation in open chan nels requires both sufficiently high strain rates for con tinued disruption of surface crusts and sufficient groundmass crystallinity to generate a yield strength equivalent to the imposed stress in hawai i where lava is typically microlite poor on eruption these combined requirements help to explain two common observations on a aformation a a aflow fields are generated when effusion rates are high thus promoting crustal disruption and b under most eruption conditions lava issues from the vent as pahoehoe and changes to a aonly after flowing some distance thus permitting sufficient crystallization

continuous monitoring of soil co2 flux on mt etna the 2004 2005 eruption and the role of regional tectonics and volcano tectonics 1 the soil co2 flux on mt etna as recorded by the etnagas network an automatic system for measuring soil co2 flux and meteorological parameters started to increase strongly about 5 months prior to the onset of the 2004 2005 eruption and decreased a few months before the end of the eruption time delays in the occurrences of anomalies in soil co2 flux at different sites in the geochemical network constrain the relationship between soil co2 flux distributions and the tectonic framework of etna volcano the anomalies observed before the 2004 2005 eruption support the intrusion of new undegassed magma into the upper feeding system of the volcano 20 km below sea level magma subsequently rose slowly in the volcano conduits thereby triggering the onset of the 2004 2005 eruption the time delays in the occurrences of anomalies in combination with spectral analysis indicate the importance of tectonic and volcanotectonic structures in driving the ascent of deep gases within the crust moreover greatest amplitude pulsations of the low frequency components of the co2 flux signals were correlated with the paroxystic activities of the 2004 2005 eruption this study confirms that co2 flux variation is a useful indicator for volcanic activity in the surveillance of the mt etna and similar basaltic volcanoes

temporal evolution of long period seismicity at etna volcano italy and its relationships with the 2004 2005 eruption abstract between december 2004 and august 2005 more than 50 000 long period events lp accompanied by very long period pulses vlp were recorded at mt etna encompassing the effusive eruption which started in september 2004 the observed activity can be explained by the injection of a gas slug formed within the magmatic column into an overlying cavity filled by either magmatic or hydrothermal fluids thus triggering cavity resonance although a large number of lp events exhibit similar waveforms before the eruption they change significantly during and after the eruption we study the temporal evolution of the lp vlp activity in terms of the source movement change of the waveforms temporal evolution of the dominant resonance frequencies and the source q factor and changes in the polarization of the signal the lp source locations before and after the eruption respectively do not move significantly while a slight movement of the vlp source is found the intensity of the lp events increases after the eruption as well as their dominant frequency and q factor while the polarization of the signals changes from predominantly transversal to pure radial motion although in previous studies a link between the observed lp activity and the eruption was not found these observations suggest that such a link was established at the latter end of the eruptive sequence most likely as a consequence of a reestablishment of the pressure balance in the plumbing system after it was undermined due to the discharge of large amounts of resident magma during the eruption based on the polarization properties of the signal and geological setting of the area a fluid filled crack is proposed as the most likely source geometry the spectral analysis based on the autoregressive models sompi is applied to the signals in order to analyse the resonance frequencies and the source q factors the results suggest water and basalt at low gas volume fraction as the most likely fluids involved in the source process using theoretical relations for the slow waves radiated from the fluid filled crack we also estimate the crack size for both fluids respectively

pleistocene sediments beneath the ross ice shelf we report here the results of new micropalaeontological studies of sediments collected from beneath the ross ice shelf at risp site j9 82 22 s 168 38 w risp sediments hold the key to understanding the history of the west antarctic ice sheet dynamics of marine based ice sheets sedimentation processes that operate beneath ice shelves and perhaps the early glacial history of antarctica risp sediments were formerly assigned an age of late middle miocene on the basis of their diatom flora our diatom analyses do not support this age assignment diatoms in risp cores are of mixed ages ranging from miocene to late quaternary thus indicating that the sediments record a history of reworking the most recent of which could have occurred no earlier than late pleistocene these results support our previous work with ross sea sediments but throw considerable doubt on a recent hypothesis concerning miocene palaeogeographical evolution of the ross sea region

intrusion of eccentric dikes the case of the 2001 eruption and its role in the dynamics of mt etna volcano abstract the 2001 eruption represents one of the most studied events both from volcanological and geophysical point of view on mt etna this eruption was a crucial event in the recent dynamics of the volcano marking the passage from a period march 1993 june 2001 of moderate stability with slow continuous flank sliding and contemporaneous summit eruptions to a period july 2001 to present of dramatically increased flank deformations and flank eruptions we show new gps data and high precision relocation of seismicity in order to demonstrate the role of the 2001 intrusive phase in this change of the dynamic regime of the volcano gps data consist of two kinematic surveys carried out on 12 july a few hours before the beginning of the seismic swarm and on 17 july just after the onset of eruptive activity a picture of the spatial distribution of the sin eruptive seismicity has been obtained using the hypodd relocation algorithm based on the double difference dd technique modeling of gps measurements reveals a southward motion of the upper southern part of the volcano driven by a nnw sse structure showing mainly left lateral kinematics precise hypocenter location evidences an aseismic zone at about sea level where the magma upraise was characterized by a much higher velocity and an abrupt westward shift revealing the existence of a weakened or ductile zone these results reveal how an intrusion of a dike can severely modify the shallow stress field triggering significant flank failure in 2001 the intrusion was driven by a weakened surface which might correspond to a decollement plane of the portion of the volcano affected by flank instability inducing an additional stress testified by gps measurements and seismic data which led to an acceleration of the sliding flanks

science at the policy interface volcano monitoring technologies and volcanic hazard management this paper discusses results from a survey of volcanologists carried out on the volcano listserv during late 2008 and early 2009 in particular it examines the status of volcano monitoring technologies and their relative perceived value at persistently and potentially active volcanoes it also examines the role of different types of knowledge in hazard assessment on active volcanoes as reported by scientists engaged in this area and interviewees with experience from the current eruption on montserrat conclusions are drawn about the current state of monitoring and the likely future research directions and also about the roles of expertise and experience in risk assessment on active volcanoes while local knowledge is important it must be balanced with fresh ideas and expertise in a combination of disciplines to produce an advisory context that is conducive to high level scientific discussion

volcano surveillance using infrared cameras abstract volcanic eruptions are commonly preceded accompanied and followed by variations of a number of detectable geophysical and geochemical manifestations many remote sensing techniques have been applied to tracking anomalies and eruptive precursors and monitoring ongoing volcanic eruptions offering obvious advantages over in situ techniques especially during hazardous activity whilst spaceborne instruments provide a distinct advantage for collecting data remotely in this regard they still cannot match the spatial detail or time resolution achievable using portable imagers on the ground or aircraft hand held infrared camera technology has advanced significantly over the last decade resulting in a proliferation of commercially available instruments such that volcano observatories are increasingly implementing them in monitoring efforts improved thermal surveillance of active volcanoes has not only enhanced hazard assessment but it has contributed substantially to understanding a variety of volcanic processes drawing on over a decade of operational volcano surveillance in italy we provide here a critical review of the application of infrared thermal cameras to volcano monitoring following a summary of key physical principles instrument capabilities and the practicalities and methods of data collection we discuss the types of information that can be retrieved from thermal imagery and what they have contributed to hazard assessment and risk management and to physical volcanology with continued developments in thermal imager technology and lower instrument costs there will be increasing opportunity to gather valuable observations of volcanoes it is thus timely to review the state of the art and we hope thereby to stimulate further research and innovation in this area

distribution and provenance of recycled palynomorphs in surficial sediments of the ross sea antarctica abstract quantitative analysis of surficial sediments in the ross sea has shown that the highest densities of recycled palynomorphs occur in a region in the southeast immediately north of the ross ice shelf in the vicinity of roosevelt island there spores and pollen of late cretaceous to early tertiary age predominate eocene dinoflagellates and rare palaeozoic spores are also present in the western half of the ross sea densities of recycled palynomorphs are lower but relative frequencies of palaeozoic types are higher on the continental shelf the palynomorphs have been recovered in equal abundance from sediments identified as basal tills and compound glaci marine sediments comparison of the observed patterns of distribution with patterns of ice flow in the ross ice shelf shows a clear correlation between the high palynomorph densities in the southeastern ross sea and discharge from ice streams d and e geophysical information from aeromagnetic and radio echo sounding surveys in the catchment areas of these ice streams suggests the most likely source for the recycled palynomorphs to be in a region of subdued topography inland of the present grounding line in the marie byrd land sector of the ross ice shelf extending probably not further east than 130 w this region probably represents a continuation of the easternmost ross sea basin the presence of marine eocene sediments there attested to by dinoflagellates in the recycled assemblages accords with suggestions of a late mesozoic cenozoic opening of the ross sea the observed patterns of palynomorph distribution reflect input from ice drainage areas in both east and west antarctica the preservation of sediments of differing provenance in distinct areas on the sea floor probably indicates processes of meltout of debris near the grounding line of the ross ice shelf during past phases of expansion marine bottom currents have not significantly redistributed the recycled microfossils

vertical and lateral propagation of radial dikes inferred from the flow direction analysis of the radial dike swarm in komochi volcano central japan dikes with lateral and outward intrusion directions named l type dike and dikes with vertical and upward intrusion directions v type dike are recognized in a radial dike swarm of komochi volcano japan by the combined analysis of the preferred orientations of deformed vesicles and anisotropy of magnetic susceptibility ams intrusion directions of magmas were examined for 41 dike outcrops among them 19 dikes were classified as l type dike and 15 dikes were as v type the l type dikes distribute over the area of the dike swarm radiating from the central conduit which is named daikokuiwa stock and the v type dikes occur mainly in the peripheral portion of the volcano the l type dikes are characterized with evolved whole rock compositions similar to those of rocks consisting of the central conduit whereas the v type dikes have less fractionated composition and are enrich in mafic phenocryst as compared to the l type dikes the outward intrusion directions of the l type dikes and their petrological similarity to the rock of the central conduit indicate that these dikes intruded from the shallow part of the central conduit where the magmas underwent fractional crystallization and degassing the petrological characteristics of the v type dikes suggest that the less fractionated magma intruded directly from a magma chamber in which mafic phenocryst crystals accumulated the larger dike thickness and higher magnetic foliation of the v type dike as compared to the l type dike indicate higher magmatic overpressure which was possibly result of the direct connection to the pressurized magma chamber and vertical growth of the dikes with buoyant magma solidification of the central conduit is favorable for the accumulation of internal excess pressure in the magma chamber to break the wall rock fissure eruptions independent of the central conduit have occurred in many volcanoes and these fissure eruptions might be fed by the dikes directly propagated from the deeper magma chamber

the borehole fluid effect in electrical resistivity imaging fluid that fills boreholes in crosswell electrical resistivity investigations provides the necessary electrical contact between the electrodes and the rock formation but it is also the source of image artifacts in standard inversions that do not account for the effects of the boreholes the image distortions can be severe for large resistivity contrasts between the rock formation and borehole fluid and for large borehole diameters we have carried out 3d finite element modeling using an unstructured grid approach to quantify the magnitude of borehole effects for different resistivity contrasts borehole diameters and electrode configurations relatively common resistivity contrasts of 100 1 and borehole diameters of 10 and 20 cm yielded for a bipole length of 5 m apparent resistivity underestimates of approximately 12 and 32 when using ab mn configurations and apparent resistivity overestimates of approximately 24 and 95 when usingam bn configurations effects are generally more severe at shorter

the electrical field in a borehole with a casing the electric field on the borehole axis in the presence of a casing can be divided into three zones the near intermediate and far zones within the intermediate zone determination of the second derivative of the potential allows me to define the formation resistivity outside the casing the electric field at large distances from the borehole has a radial direction that provides a sufficient depth of investigation in this direction the measurement requires knowledge of the casing conductance application of transmission line theory is based on the fact that the electric field in the formation is radial within the intermediate zone resulting in the conclusion that the vertical resolution of such a measurement would depend only upon the spacing of the electrodes required to estimate the second derivative of the potential

effects of well casing on potential field measurements using downhole current sources1 a mathematical formulation for the electric potential from point current sources coaxial with a metal casing has been obtained the excitation caused by the axial point sources will produce currents in the pipe by assuming that the pipe can be divided into many cylindrical ring segments with constant axially directed current the solution of the fields inside and outside the pipe can be formulated in an integral form the integral equation applied to the segmented pipe yields a set of simultaneous linear equations which are solved for the currents in the pipe these are then used to calculate the potentials anywhere outside the pipe in the medium this solution has been used to study the distribution of the potentials in a half space for a single current source at and beyond the bottom of a finite length of casing for a casing 0 1 m in radius and 0 006 m in wall thickness with a conductivity of 106 s m in a half space of 10 2 s m it was found that only in a region very near the pipe does the pipe exert substantial influence on the fields of a point source 100 casing diameters beyond the end of the pipe it appears that cross hole resistivity surveys can be implemented without corrections for the casing if the source is located at least 50 100 casing diameters beyond the end of the casing hole to surface surveys are much more affected by the pipe for a pipe source separation of 100 casing diameters the surface measurements must not be closer than a half pipe length for a 5 or less field distortion

magma dynamics in the shallow plumbing system of mt etna as recorded by compositional variations in volcanics of recent summit activity 1995 1999 describe the reactivation and the successive evolution of the shallow plumbing system of mt etna between the end of the largest flank eruption of the last three centuries 1991 1993 and the subterminal eruption from south east crater sec which occurred between february and mid november 1999 our analysis is based on observations of the volcanic activity and petrological studies of the erupted volcanics bulk rock mineral and glass compositions have been determined for more than 80 samples erupted from the four summit craters between october 1995 and february 1999 these data allow us to recognise significant compositional variations among the products of different craters in particular volcanics produced between 1995 and 1999 by bocca nuova bn voragine vor and north east crater nec show limited compositional variations and are similar to those observed during recent eruptions e g 1991 93 more primitive magmas have been produced during the more vigorous fire fountains episodes on the contrary the south east crater produced slightly more differentiated volcanics than those of the other summit craters following its reactivation november 1996 until the end of 1998 whole rock compositions of products from this crater show low cao al 2 o 3 whereas interstitial glasses have lower mgo and higher alkali contents than those from the other craters however since the beginning of 1999 and just before the start of the subterminal eruption from sec the volcanics erupted from this crater progressively changed in composition becoming similar to those of the other craters this trend indicates that within the conduits of the summit craters distinct thermal and fluid dynamical regimes can evolve controlling the cooling and crystallisation of etna magmas

interpretation of sediment cores from the ross ice shelf site j 9 antarctica reply by thomas b kellogg davida e kellogg interpretation of sediment cores from the ross ice shelf site j 9 antarctica reply by thomas b kellogg davida e kellogg

diagenesis of sediments beneath the ross ice shelf and their sedimentary history micropalaeontological studies of sediment cores collected from beneath the ross ice shelf antarctica give conflicting stratigraphical interpretations the diatom flora initially indicated an in situ succession of later middle miocene age1 2 which was supported by the occurrence of benthic foraminifera3 however subsequent diatom analyses record the presence of flora with mixed ages mostly miocene but also pliocene and pleistocene throughout both of the two lithological units present in the cores these flora are taken to indicate repeated reworking which most recently occurred no earlier than the late pleistocene4 these contrasting views have since been re affirmed5 6 our studies of sediment geochemistry show self consistent patterns in organic carbon organic nitrogen and sulphur diagenesis which suggest a recent in situ origin at least for the upper unit

bedrock platforms within the ross embayment west antarctica hypotheses for ice sheet history wave erosion cenozoic extension and thermal subsidence ice penetrating radar mostly airborne and marine seismic surveys have revealed plateaus and terraces about 100 350 m below sea level beneath parts of the ross embayment including the west antarctic ice sheet the ross ice shelf and the eastern ross sea these surfaces cover many thousands of square kilometers and are separated by bedrock troughs occupied by the west antarctic ice streams prominent plateaus are under edward vii peninsula siple dome and roosevelt island marine seismic data and gravity data over the buried plateaus support an interpretation that they were caused by erosion into basement the flat and level nature of the surfaces that were formed by erosion are near the same depth over large distances and fringe the buried rugged bedrock topography of marie byrd land supports an interpretation of marine rather than glacial erosion marine seismic reflection profiles over one of the plateau remnants show it as an angular unconformity cut into gently dipping sediments of late oligocene age draped with thin flat lying sediments implying that the plateau is early miocene or younger the younger limit for plateau erosion follows from the interpretation of the mechanism erosion must predate permanent ice along the coast associated with the growth of the west antarctic ice sheet probably prior to 10 ma and possibly prior to 14 ma the plateaus along the siple coast with depths around 350 meters do not rebound to close to sea level and wave base for models of removing past and present ice load this discrepancy can be explained if ross embayment lithosphere has been cooling and subsiding since significant extension in eocene to oligocene time our interpretation requires crustal subsidence in the ross sea which in turn implies higher bedrock elevations in the past within this region higher standing topography presented an opportunity for the accumulation of local ice sheets and caused sea level fluctuation prior to late cenozoic time

maceral total organic carbon and palynological analyses of ross ice shelf project site j9 cores analyses of macerals and total organic carbon indicate that the low organic content of core sediments from ross ice shelf project site j9 has been selectively reduced further probably by postdepositional submarine oxidation palynological analysis revealed a reworked paleogene dinocyst flora of low diversity the transantarctic flora this constitutes the most southerly dinocyst flora reported thus far the antarctic distribution of the transantarctic flora supports the existence of a transantarctic strait during the paleogene the j9 sporomorph assemblage also is reworked and paleogene in age

dynamics of 2004 2005 mt etna effusive eruption as inferred from petrologic monitoring 1 from early september to early november during the 2004 2005 mt etna effusive eruption petrologic monitoring was enabled by near vent sampling of erupting lava and onsite sem eds capabilities at ingv ct significant differences in composition and temperature of lava erupted from 2920 2620 m and 2820 2320 m vents attest to variably evolved shallow magmatic conditions within a geometrically complex storage volume the petrography and glass compositions of water quenched samples indicate that the magma feeding the 2004 2005 activity was likely to have been stored in the shallow plumbing system during the 2000 and 2001 activity where it experienced volatile loss and extensive crystallization both geophysical and petrologic data suggest that this eruption was not triggered by the intrusion of a new dike from depth but it was more likely that existing shallow magma reservoirs were passively mobilized and erupted in response to edifice deformation

multiple miocene marine productivity events in west antarctica as recorded in upper miocene sediments beneath the ross ice shelf site j 9 abstract considerable debate surrounds the age and origin of sediments recovered from underneath the ross ice shelf antarctica at site j 9 although diatom biostratigraphy provides the best means of dating these sediments diatom fragmentation sediment reworking and microfossil assemblage mixing have led to conflicting interpretations regarding the age and depositional history of sediments collected as part of the ross ice shelf project r i s p our biostratigraphic approach differs from previous analyses of r i s p sediments by differentiating between microfossil assemblages recovered from the sediment matrix and from within abundant semi indurated sediment clasts diatomaceous clasts that were eroded and transported to site j 9 by glacier ice reveal the age and composition of unknown marine deposits in west antarctic interior basins in addition to rare reworked paleogene and cretaceous microfossils three distinct miocene diatom assemblages are recognized two from sediment clasts middle lower miocene and early middle miocene and a third restricted to matrix sediments middle upper miocene contrary to some published reports no microfossils unequivocally younger than middle late miocene are present other than modern subice shelf benthic foraminifera and ostracodes found in the uppermost sediments whether r i s p sediments are an in situ glacimarine deposit or a basal till is still uncertain however new data presented here support deposition by glacial marine processes during the middle late miocene an age indicated by foraminifera and the youngest diatom assemblage in r i s p pliocene and pleistocene marine sediments were probably stripped off by subsequent ice grounding events most likely in association with the ross sea unconformity reworked sedimentary clasts of diatomite suggest a highly productive open marine environment in west antarctica with intense productivity and limited glacial ice at sea level in the ross sea embayment during the middle early miocene

sediment core from beneath the amery ice shelf east antarctica suggests mid holocene ice shelf retreat the stability of floating ice shelves is an important indicator of ocean circulation and ice shelf mass balance a sub ice shelf sediment core collected during the austral summer of 2000 2001 from site am02 69 42 8 s 72 38 4 e on the amery ice shelf east antarctica contains a full and continuous record of glacial retreat the am02 core site is 80 km south of the floating ice shelf edge and contains a 0 5 m thick holocene surface layer of siliceous mud and diatom ooze of marine origin core data are supportive of sub ice shelf circulation models that predict the landward flow of oceanic water and prove that the landward transport of hemipelagic sediments occurs beneath floating ice shelves over distances of at least 80 km an increase in sea ice associated diatom deposition in the upper part of the holocene suggests that a major retreat of the amery ice shelf to at least 80 km landward of its present location may have occurred during the mid holocene climatic optimum

unravelling the magma feeding system of a young basaltic oceanic volcano abstract a multidisciplinary approach combining petrological geochemical and fluid inclusion studies with seismic monitoring data was used to build a model of the magma feeding system of pico volcano azores islands north atlantic ocean we explore how magma has ascended to the surface in the last 10 ka and how this ascent is associated with the selective activation of the three tectonic systems intersecting the volcano the deepest and most important ponding level for all ascending magmas is located at 17 3 17 7 km and corresponds to the moho transition zone mtz which marks the transition from mantle rocks to ultramafic cumulates at shallower depth ascending magmas carry 30 vol of clinopyroxene and olivine each magma ascent followed a distinct path and ponded often for a limited period ponding levels common to all feeding systems are present at 16 3 16 7 km 12 1 14 5 km 9 4 9 8 km and 7 7 8 1 km these depths mark important discontinuities where magmas formed stacked sills and evolved through fractional crystallisation dense and un decrepitated fluid inclusions show rapid ascent from the mtz along the lomba do fogo sao joao fault n150 system and along the n120 regional transtensive system despite multiple intrusions magma ponding at 5 6 6 8 km occurs where the n150 and n60 tectonic systems intersect each other here magma evolves towards plagioclase rich and is only erupted at the summit crater and subterminal vents this region is the source of the frequent microseismicity recorded at 4 to 7 km beneath the southern flank of pico volcano which might be associated with the early stages of formation of a more complex magma reservoir the local and regional tectonics are of paramount importance in the activation of the different magma feeding systems over time this new information is fundamental to improve the knowledge on the future eruptive behaviour of pico volcano and can have significant implications on the mitigation of volcanic risk this multidisciplinary approach can be applied not only to other volcanoes of the azores but also to poorly monitored oceanic volcanoes where magma ascent strongly depends on the activation of tectonic systems

magma transport and storage at mt etna italy a review of geodetic and petrological data for the 2002 03 2004 and 2006 eruptions abstract a detailed reconstruction of magma movements within the plumbing system of mt etna volcano has been made by reviewing the eruptions occurring during the october 2002 december 2006 period the availability of continuous gps data allowed detecting at least ten different ground deformation stages highlighting deflationary and inflationary episodes as well as the occurrence of a shallow dike intrusion these data have been coupled with the available petrological datasets including major trace elements and sr nd pb isotope compositions for the volcanic rocks erupted in the 2002 2006 period we identified two main magmatic reservoirs located at different depths along the plumbing system of the volcano the former is located at a depth of 7 km bsl and fed the 2001 and 2002 03 eruptions while the latter located from 3 5 to 5 5 km bsl fed the 2004 05 and 2006 eruptions petrological characteristics of emitted products have been correlated with the inflation vs deflation cycles related to the identified sources providing evidence for changes through time of the evolutionary degree of the erupted magmas along with variations in their geochemical feature finally we suggest that a modification of the deep plumbing system of the volcano might have occurred during the 2002 03 eruption as a consequence of the major seaward motion of the eastern flank of the volcano