object oriented classification of a high spatial resolution spot5 image for mapping geology and landforms of active volcanoes semeru case study indonesia the present work explores the object oriented classification ooc of high spatial resolution hsr satellite panchromatic imagery for mapping the geology of the persistently active semeru volcano and its ring plain east java indonesia a panchromatic spot5 image and a digital elevation model dem have been used to identify geologic units structures landforms and deposits the panchromatic image was georeferenced and enhanced using histogram equalization the enhanced image was segmented into polygons using the envifx exelis software the polygons were delineated and classified on the basis of spectral panchromatic hues and textures topographic slope elevation information and geologic geomorphic processes the validity of classification was evaluated by interpreting google earth images aerial photographs and limited field observations the classification consists of three hierarchical levels across the volcanic area of about 745 km2 the first operational spatial level includes seven large volcano domains based on the spectral content of the volcanic tectonic and lithological structures and principal catchments the second operational level based on contextual relationships topography drainage network vegetation cover type stratigraphy and slope dynamics encompasses 20 geological units that range between 30 and 80 km2 in area among the units the third operational level distinguishes as many as 47 geomorphological sub units 0 25 25 km2 according to slope gradient deposit type mass wasting process and weathering the resulting map provides a detailed pattern of geologic and geomorphic features unlike previous geologic maps that identified only 11 stratigraphic units we show that the high spatial resolution panchromatic spot5 scene can help to safely map the geology and landforms of persistently active volcanoes such as semeru we have applied the ooc technique on one hsr geoeye panchromatic image to map another active volcano merapi in central java after considerable geomorphic changes due to the large eruption in 2010

influence of cone morphology on dykes stromboli italy abstract the island of stromboli represents the emerged part of a 2 6 km high composite volcano elongated in a ne direction over the period 100 13 ka bp the morphological evolution of the volcano was characterised by a series of summit caldera collapses between major building phases from 13 ka bp onward a series of large lateral collapses occurred northwestwards in one sector of the cone the results of the field study of the total 94 dyke population is discussed in this paper they show that during the last 100 ka the majority of dykes were injected with a nnegssw to ene wsw strike along a ne sw weakness zone crossing the volcano summit this is interpreted as a volcanic rift the geometry of which is controlled by regional tectonic stresses dykes injected prior to 13 ka bp at lower altitudes are generally steeper than those injected at higher elevations after 13 ka bp dykes were injected along the ne sw weakness zone and parallel and close to the margins of the earliest sector collapse at dips of 20 80 inclined towards the collapse depression i suggest that this is linked to unbuttressing of the collapse depression or to seaward gravity instability of the depression infill deposits extensive emplacement of long dykes along the ne sw weakness zone occurred only when the volcano regained a conical shape some of the dykes emplaced close to the original surface of the cone bent to assume a dip direction parallel to the local slope i propose that this local change of dyke geometry can be explained by the direct influence of the free surface of the cone leading to a rotation of the least principal stress which assumes an orientation perpendicular to the slope

monitoring volcano slope instability with synthetic aperture radar a review and new data from pacaya guatemala and stromboli italy volcanoes abstract volcano slope instability manifests in many forms ranging from steady state to punctuated movement or shallow erosion to deep seated spreading the interplay of gravity magmatic or hydrothermal fluids and often active tectonics on a volcanic edifice results in complex spatial and temporal variations in deformation kinematics while this makes the recognition assessment and monitoring of volcano slope instability challenging advancements in synthetic aperture radar sar technology have significantly accelerated our knowledge of instability phenomena and our ability to assess their hazards this review discusses the applications and challenges of sar imagery to various slope instabilities at volcanoes around the world sar amplitude images are powerful tools for mapping areas of geomorphological changes these snapshots can be combined using interferometric sar insar to create multi temporal deformation maps that provide unique information on the evolution of slope failures space borne insar has become an economic way to detect changes at volcanoes at very high resolution ground based insar gbinsar can produce frequent sar images on the order of seconds to minutes propelling insar from monitoring to surveillance and early warning applications however interpreting insar derived ground deformation signals related to volcano slope instability is still challenging deformation from magma rise or variations in hydrothermal systems may be inseparable from persistent deep seated flank motion similarly shallow or localized ground motion may occur in overlap with thermal contraction or subsidence of newly emplaced lava or tephra deposits if triggered to failure landslides can vary over several magnitudes from small volume rock falls that pose only a localized hazard to large volume debris avalanches capable of travelling tens of kilometers away from the source these collapses can have cascading hazards if accompanied by directed blasts or tsunamis emphasizing the need for continued advancement of our understanding of these events and their consequences to highlight the utility of sar for measuring and monitoring mass movement two case studies of stromboli italy and pacaya guatemala volcanoes are discussed in detail where recent instability events persistent volcanic activity and ground truth constraints have resulted in excellent case histories in applying sar imagery to understand these potentially hazardous slope instabilities

new geophysical insight into the dynamics of stromboli volcano italy abstract a 56 hour gravity sequence recorded in the crater area of stromboli volcano is presented data were acquired during a period of normal strombolian activity high frequency gravity anomalies up to 20 gal t tens of seconds are observed comparison with independent data reveals that these changes reflect the response of the gravimeter excited by seismic waves during strombolian explosions correlated changes in the energy distribution over time appear in the continuous wavelet transforms of gravity and rms tremor but over different scales corresponding to periods centered at about 50 and 25 min for gravity and tremor respectively we infer that the rate of fresh magma supply to the shallow feeding system controls the energy distribution over time of the coupled components in gravity and rms tremor signals in particular the gravity signal with an average amplitude of 1 2 gal could be induced by temporary accumulations at shallow depth of the volatiles discharged by quiescent degassing changes in the rate of explosions from the summit craters correlate with changes in the amplitude of the coupled gravity and volcanic tremor oscillations implying that even though the slug genesis process behind the explosions occurs at deeper levels it is also controlled by the rate of gas rich magma supply from below negative gravity anomalies of about 20 gal over intervals of some hours are also observed separated by intervals of about 24 h they could be induced by increases in magma vesicularity in the uppermost part of the conduit plexus a view supported by i changes in the time space distribution of tremor amplitudes and ii increases in spattering activity from a summit vent both occurring during the development of the negative gravity anomalies the processes behind mild strombolian explosions do not trigger measurable gravity changes nevertheless the slug ascent before a major explosion could induce a precursory gravity signal

lithospheric and upper mantle structure of southern tibet from a seismological passive source experiment fifteen seismic stations were operated with about 20 km spacing in southern tibet across the zangbo suture the collision zone between india and asia between may and october 1994 as part of the international deep profiling of tibet and the himalaya project indepth ii for wide angle recording of the controlled source experiment and for passive earthquake recording in addition a dense deployment 4 km spacing of stations within the german depth profiling of tibet and the himalayas gedepth project also recorded a number of teleseismic earthquakes the third data source used in this study is the records of the permanent broadband station at lhasa teleseismic records have been obtained in sufficient quantity and quality to derive an image of the structure of the lithosphere and upper mantle from p to s converted phases important results are as follows the moho at 70 80 km and a second discontinuity at 50 60 km depth are observed over the entire profile south and north of the zangbo suture the data from the gedepth dense array enable the detection of inclined structures penetrating the crust at the zangbo suture a pronounced low velocity zone exists north of the zangbo suture at about 10 20 km depth the locations of the upper mantle discontinuities at 410 and 660 km depth are in agreement with the global reference model iasp91 kennett 1991 over a large region of the himalaya and southern tibet

sound velocities of majorite garnet and the composition of the mantle transition region the composition of the mantle transition region characterized by anomalous seismic wave velocity and density changes at depths of approximately 400 to 700 km has remained controversial some have proposed that the mantle transition region has an olivine rich pyrolite composition whereas others have inferred that it is characterized by pyroxene and garnet rich compositions piclogite because the sound velocities in pyrolite estimated from laboratory data are substantially higher than those seismologically observed although the velocities of the olivine polymorphs at these pressures wadsleyite and ringwoodite have been well documented those of majorite another significant high pressure phase in the mantle transition region with realistic mantle compositions have never been measured here we use combined in situ x ray and ultrasonic measurements under the pressure and temperature conditions of the mantle transition region to show that majorite in a pyrolite composition has sound velocities substantially lower than those of earlier estimates owing to strong nonlinear decreases at high temperature particularly for shear wave velocity we found that pyrolite yields seismic velocities more consistent with typical seismological models than those of piclogite in the upper to middle parts of the region except for the potentially larger velocity jumps in pyrolite relative to those observed at a depth of 410 km in contrast both of these compositions lead to significantly low shear wave velocities in the lower part of the region suggesting possible subadiabatic temperatures or the existence of a layer of harzburgite rich material supplied by the subducted slabs stagnant at these depths

failure of volcano slopes magmatic intrusions can initiate and sustain massive and catastrophic volcano collapse their role is twofold involving both driving and resisting forces first flank stability is diminished by magmastatic and magma overpressures and steepened slopes that accompany intrusion second excess pore pressures in potential failure zones can be generated as a result of intrusion related mechanical or thermal straining of the rock fluid medium pressurized retrograde boiling in high level magma chambers or hydrothermal fluid circulation also earthquakes may aid collapse through inertial forces and shaking induced pore pressure generation these excess pore pressures reduce the sliding resistance as shown for wedge shaped slide blocks for selected cases the destabilizing influence of mechanically induced pore pressures is maximized as the intruded width or corresponding overpressure of the intrusion is increased the destabilizing influence of thermally induced pore pressures is conditioned by the seve

moho geometry and upper mantle images of northeast india 1 images of the crust and mantle beneath northeast india obtained by 2d migration of 1000 broadband p receiver functions clearly trace a northward dipping moho from the himalayan foredeep reaching depths up to 50 km further north beneath the himalayan convergence zone also these images reveal presence of largely coherent 410 km and 660 km discontinuities that conform to the iasp91 model marginal variations in the depth of the 410 km interface are observed that appear region specific the thickness of the mantle transition zone does not deviate significantly from a global average of 250 km interestingly our results reveal consistent presence of a signal from an interface around 300 km origin of such a boundary known as x discontinuity and unrelated to the lehmann discontinuity is discussed possible presence of the x discontinuity from the indian region is reported here for the first time

seismic observations of splitting of the mid transition zone discontinuity in earth s mantle the transition zone of earth9s mantle is delineated by globally observed discontinuities in seismic properties at depths of about 410 and 660 kilometers here we investigate the detailed structure between 410 and 660 kilometers depth by making use of regional stacks of precursors to the ss phase the previously observed discontinuity at about 520 kilometers depth is confirmed in many regions but is found to be absent in others there are a number of regions in which we find two discontinuities at about 500 and 560 kilometers depth an effect which can be interpreted as a splitting of the 520 kilometer discontinuity these observations provide seismic constraints on the sharpness and observability of mineralogical phase transitions in the mantle transition zone

what controls sheet intrusion in volcanoes structure and petrology of the stromboli sheet complex italy abstract a multidisciplinary study has been conducted on 109 intrusive sheets of stromboli the relation between sheet injection conditions with the magmatic and structural variations of the volcano and the parameters governing the preferential intrusion geometry inside the volcano in a time perspective have been determined during its subaerial activity the last 100 ka stromboli experienced periods of extrusive growth and sheet intrusions alternated to caldera and lateral collapses of the nw sciara del fuoco flank the sheet intrusions similar to the extrusive rocks span a large compositional range from calc alkaline to potassic through high k calc alkaline and shoshonitic series the most evolved compositions of the effusive rocks however have not been found as intrusions whereas some mafic and basic magmas of sheets were never erupted the repeated time change of location of the intrusions from strombolicchio to the ne sw trend passing trough the inferred paleostromboli summit cone and the southern flank could represent the expression of the shift of the magma chamber towards the southeast and the subsequent onset of a clear ne sw elongated magma chamber located along the main stromboli weakness zone the stromboli evolution in the last 100 ka has been characterized by the persistent n 10 55 e intrusion direction which reflects the influence of the edifice s state of stress on the magma feeding paths after 13 ka ago sheets mainly intruded along to the sector collapse scarps in a circum amphitheatre geometry which has been demonstrated to be influenced by the new cone morphostructure and not by different magma rheological characters

upper mantle seismic shear discontinuities of the pacific 1 shear wave impedance discontinuities are inventoried for eight paths connecting circum pacific earthquakes with seismic stations on hawaii and oahu in addition to the transition zone discontinuities we observe a consistent impedance decrease at a depth of 80 km that marks the transition from the fast seismic lid to the low velocity zone the interval over which this transition occurs is less than 30 km the requisite impedance decrease ascribed almost entirely to diminished velocities in the low velocity zone exceeds predictions for peridotite chemistries of appropriate lithospheric age in all cases the transition is better matched by lithosphere of roughly half of the true age four paths show clear evidence of the x discontinuity an impedance increase of 3 8 near 300 km depth the only viable explanations would require extensive eclogite or basalt depleted mantle in the upper mantle of the western pacific the impedance contrast of the 410 km discontinuity which depends on the modal fraction of mantle olivine does not signal the presence of either although a mixture of the two remains a possibility we find no evidence of a low velocity layer atop of the 410 km discontinuity if present it is either consistently thin 15 km highly variable in thickness topography in excess of 60 km or has little impedance contrast 2 3 with overlying mantle the apparent absence of melt atop the 410 km discontinuity an intermittent and weak 520 km discontinuity and a thinned transition zone are consistent with relatively dry conditions in the deep upper mantle of the central pacific

seismic evidence for accumulated oceanic crust above the 660 km discontinuity beneath southern africa 1 high pressure assemblages of subducted oceanic crust are denser than the normal upper mantle but less dense than the uppermost lower mantle thus subducted oceanic crust may accumulate at the base of the upper mantle direct observational evidence for this hypothesis however remains elusive we present an analysis of a negative polarity shear wave converted from compressional wave at a seismic discontinuity near 570 600 km depth beneath southern africa the negative polarity of the converted phase indicates a 2 2 0 2 s velocity decrease with depth at the seismic discontinuity this velocity reduction is associated however with a low velocity contrast at the 660 km discontinuity the exsolution of ca perovskite in former oceanic crust at depth greater than 600 km and the associated small volume fraction of ringwoodite are plausible explanations for the apparent paradox between the negative velocity discontinuity and the low velocity contrast at the 660 km discontinuity

flank instability of stromboli volcano aeolian islands southern italy integration of gb insar and geomorphological observations abstract stromboli is characterized by frequent explosions of variable energy and periodically interrupted by more energetic blasts emitting large volumes of material the pressurization of a volatile poor high porphyritic magma column that is gas recharged by the deep seated volatile rich low porphyritic magma precedes such events and produces deformations on the nw flank of the volcano sciara del fuoco by integrating geomorphological observations with long term displacements from ground based interferometric radar since december 2007 we identified two landslides whose movements are strongly related with volcanic activity movement patterns obtained through a novel long term analysis of gb insar data permitted us to hypothesize the type of movement and depth for both landslides furthermore their position allowed us to affirm that the effusive vent formed in 2007 at 400 m a s l was the result of the deflection of a feeder dike caused by landslide fractures thus showing the important role of geomorphological discontinuities in volcanic environments

preferential detection of the lehmann discontinuity beneath continents we perform a global survey for the presence of the lehmann discontinuity using 20 000 long period ss precursors this data set is highly sensitive to upper mantle reflectors and the coverage is more complete than in previous studies our survey indicates that the lehmann discontinuity is a local feature that is observed under continents more than twice as often as it is observed under oceans we observe significant variations in travel times and waveforms associated with this shallow mantle reflector indicating its complexity and lateral depth variations little signal is detected on the continent scale stacks of the ss precursors which provides further evidence for the intermittent and variable nature of the lehmann discontinuity

ground based insar reveals conduit pressurization pulses at stromboli volcano at stromboli volcano southern italy only few minor precursors gas output have been identified for major strombolian explosions we use ground based interferometric synthetic aperture radar gbinsar technology to monitor the displacement rate of the summit area of stromboli we analysed the 2009 2011 period the analysis of the displacement rate has been performed by dividing the summit zone monitored by the gbinsar into three regions corresponding to the edge of the crater area 1 and 2 and to the slope of the ne crater 3 pulses of rapid expansion of sector 3 of variable duration and amplitude appear in coincidence with periods of intense activity that include lava flows and major explosions we associate this expansion with the pressurization of the magma column that is recharged by deep derived gas promoting the onset of major explosion dominated activity

decrypting geophysical signals at stromboli volcano italy integration of seismic and ground based insar displacement data we present the integration of seismic and ground based interferometric synthetic aperture radar system gbinsar displacement data at stromboli volcano ground deformation in the area of summit vents is positively correlated with both seismic tremor amplitude and cumulative amplitudes of very long period vlp signals associated with strombolian explosions changes in vlp amplitudes precede by a few days the variations in ground deformation and seismic tremor we propose a model where the arrival of fresh gas rich magma from depth enhances gas slug formation promoting convection and gas transfer throughout the conduit system at the shallowest portion of the conduit an increase in volatile content causes a density decrease expansion of the magmatic column and augmented degassing activity which respectively induce inflation of the conduit and increased tremor amplitudes the temporal delay between increase of vlp and tremor amplitudes conduit inflation can be interpreted in terms of the different timescales characterizing bulk gas transfer versus slug formation and ascent

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

the cretaceous sedimentary history of the pindos basin greece the cretaceous sedimentary rocks of the pindos zone in western greece document the evolution of a tethyan deep water basin new sedimentological and micropalaeontological studies reveal a complex basin history siliceous sediments with abundant radiolaria and organic rich facies prevailed up to the early late cretaceous within the sediment starved pre middle cenomanian marked black shale levels appear that are probably linked to oceanic anoxic events at the change from the late early to the early middle cenomanian the sedimentary regime altered abruptly the early late cretaceous is characterized by major calcareous redepositional events orbitoline horizons and often associated siliciclastic turbidite deposition submarine fan environments in the late late cretaceous carbonate supply increased rapidly resulting in the evolution of a carbonate slope and basin plain setting pelagic and allodapic limestones recorded basinwide blooms in planktonic foraminifera elevata event and a polyphase redepositional history that is interpreted to reflect the sensitivity of the basin to the tectonic evolution of apulia

phase transformations in subducted oceanic crust and buoyancy relationships at depths of 600 800 km in the mantle abstract phase transformations in a representative oceanic crust composition morb have been studied at pressures up to 28 gpa at 1200 c and 1500 c using a multi anvil apparatus the assemblage of majorite casio 3 rich perovskite stishovite which is displayed by the morb composition at pressures above 20 gpa was found to transform further into an assemblage containing a new aluminous phase at pressures above 25 gpa this al phase has a complex composition and is also relatively sodium rich its x ray diffraction pattern is similar to that observed for mgal 2 o 4 calcium ferrite type and is tentatively indexed on the basis of an orthorhombic cell yielding a zero pressure density of 3 87 2 g cm 3 majorite garnet was found to remain as the most abundant phase at the highest pressure studied 28 gpa and does not appear likely to transform to perovskite until pressures exceed 29 30 gpa these results imply that the basaltic crust component of subducted oceanic lithosphere would be 0 1 0 2 g cm 3 less dense than surrounding mantle pyrolite between the depths of 660 800 km thereby confirming an earlier hypothesis of anderson moreover the underlying layer of harzburgite would be 0 05 g cm 3 less dense than pyrolite throughout most of this depth interval these buoyancy relationships contribute to a barrier which impedes and may sometimes prevent the entry of slabs into the lower mantle

paroxysmal activity at stromboli lessons from the past the persistent normal activity of stromboli is occasionally interrupted by sudden and highly energetic explosive events called strombolian paroxysms these phenomena together with landslide generated tsunamis represent the most hazardous manifestations of present day volcanic activity at stromboli the most recent paroxysms on 5 april 2003 and 15 march 2007 have drawn attention to these energetic events because they significantly threatened inhabitants and tourists historical accounts and field evidence indicate however that even larger paroxysms in terms of volume dispersal of products and intensity of explosive phenomena occurred in the recent past during these paroxysms incipiently welded spatter deposits mantled the north and south rims of the sciara del fuoco down to low elevations extending much farther than the similar deposits from recent observed events 5 april 2003 and 15 march 2007 in order to identify characterize and discriminate among products of these outstanding spatter forming eruptions more than 50 stratigraphic sections were measured and sampled stratigraphic sedimentological and radiometric 14c data indicate that only two paroxysms produced spatter that reached very low elevations and inhabited areas the first occurred in the 16th century and the last in ad 1930 analysis of texture and deposit components reveals that the early phases of the two eruptions were driven by distinctly different eruptive dynamics both identified paroxysms are at least one order of magnitude greater than any similar event observed by monitoring systems at stromboli these two large paroxysms were the most powerful volcanic events at stromboli in the last eighteen centuries

deformation of stromboli volcano italy during the 2007 eruption revealed by radar interferometry numerical modelling and structural geological field data abstract the activity of stromboli volcano is characterized by very low energy explosions occurring every 10 15 min throwing out lava above the crater rim during 2007 the volcano showed an anomalous activity in which new effusive vents developed 27 february and 9 march and a major explosion took place on 15 march this paper presents an integrated study based on a structural geological field survey interferometric radar monitoring and numerical modelling on the deformations of the upper nw flank of the volcano sciara del fuoco sdf the field survey carried out during the 2007 events shows the development of mainly ne striking fissures and fractures on the northern part of the upper sdf in january 2007 the ground based synthetic aperture radar gb insar installed on the flank of the sdf showed a progressive acceleration of movement on the ne crater preceding the eruption of 27 february 2007 by the first half of february the acceleration also involved the upper portion of the sdf and on 27 february the eruption started with the opening of new vents and deformation rates higher than the measurement capability of the radar device on 8 9 march 2007 the gb insar highlighted the formation of a bulge on the nw sector of the sdf preceding the opening of an additional vent to understand the deformation pattern recorded during the eruption a numerical simulation was carried out by using the flac 3d code based on the integration of all the data the deformations observed in the pre effusive phase before 27 february seem to be related to the intrusion of a sw ne striking dyke the bulging recorded before the 9 march vent opening is instead to be associated with the intrusion of a sub horizontal sill

significance of radiolarian age data to the mesozoic tectoni and sedimentary evolution of the northern pindos mountains greece radiolarians were extracted from siliceous sediments of the northern pindos mountains in an attempt to establish the chronology of tectonic and stratigraphic events related to the evolution of the pindos ocean basin three separate phases of siliceous sedimentation were identified i mid late triassic ii mid late jurassic and iii mid late cretaceous the first two phases are also known from the pindos and sub pelagonian zones of southern and central greece and elsewhere in the dinarides andhellenides however the occurrence of cretaceous radiolarites in the west central tethyan region is somewhat unusual field observations suggest thatfrom the mid late triassic through to the mid jurassic radiolarites were deposited on volcanic basement or were interbedded with sediments associated with the late rifting spreading stages in the development of the pindos ocean radiolarites of mid late jurassic age are commonly interbedded with clastic sediments of ophiolitic derivation this coincides with a phase of significant compression within the hellenides which caused intra oceanic deformation of the pindos ophiolite the ophiolite was subsequently emplaced onto the margin of the pelagonian microcontinent in latest jurassic time kim meridgian early tithonian as evidenced by transgressive marine carbonates however the pindos basin survived in reduced form until the early tertiary allowing radiolarites to accumulate again within cretaceous post tectonic clastic sequences

subaerial submarine evidence of structures feeding magma to stromboli volcano italy and relations with edifice flank failure and creep abstract structural field data including parameters of 109 sheets strike mostly n10 55 e average dip angle mostly 70 90 average thickness two peaks at 1 2 m and 4 2 m and of 14 eruptive fissures and vents as well as bathymetric and numerical data suggest that stromboli experienced the development of a volcanic rift zone across the cone summit with a tendency to widen towards the lower submarine flanks during the last 100 ka inside this rift zone intrusive sheets mostly strike ne and become more abundant more steeply dipping and thicker on approaching the rift axis this rift persistence reflects the edifice s state of stress with a nw se horizontal least principal stress on the magma intrusion paths after 13 ka ago sheets mainly intruded with a horseshoe shaped geometry in plan view along the boundaries of the northwestern unstable volcano flank where four main lateral collapses occurred during the last 13 ka they also intruded with a ne strike across the volcano summit and the northeastern volcano flank the horseshoe shaped geometry is influenced by the lateral creep of the volcano flank which provides space for intrusion along the transtensional boundaries of the unstable sector where thinner sheets were emplaced when the collapse depression was filled up by new deposits ne striking thicker dykes emplaced across the northwestern volcano flank indicating a rapid re establishment of regional tectonic forces across the cone unbuttressing due to the present sciara del fuoco depression and ongoing flank creeping can account for intrusions also inside the sciara del fuoco the latter in 2007

onset of the persistent activity at stromboli volcano italy stromboli known worldwide as the lighthouse of the mediterranean is commonly believed to have been in a state of persistent activity for the past 2000 2500 years however historical sources older than 1000 a d are not accurate enough to assess if the activity of the volcano was exactly the same as we see at present in order to attempt to identify the onset of the present eruptive regime and assess if it has been maintained with the same characteristics through time stratigraphic and radiometric studies of the recent tephra deposits were undertaken up to 4 m deep stratigraphic trenches dug at a height of approximately 500 m on the ne flank of the volcano exposed a conformable tephra pile containing charcoal fragments one of the most interesting finds was the discovery of a 7 cm thick weathered bed rich in organic matter thin palaeosol approximately 3 m below the surface the sequence underneath the palaeosol consists of decimetre thick lapilli fallout beds alternating with ash deposits bearing small charcoals with calibrated ages of between the fourth century b c and the first century a d the sequence above the palaeosol is charcoal free and consists of coarse ash deposits with discrete centimetre thick lapilli fallout beds composed of crystal poor golden pumice and subordinate crystal rich black scoriae similar to scoria pumice pairs emitted during the more energetic explosions of the present day activity the data collected indicate that between the third and seventh centuries a d after a period of quiescence the activity resumed with an eruptive style identical to the present one we conclude that the lighthouse of the mediterranean actually began its activity in a period much later than previously thought

sinkhole monitoring and early warning an experimental and successful gb insar application abstract sinkholes represent a natural risk that may hit catastrophically without clearly detectible precursors however they are often overlooked by people and administrators therefore sinkhole monitoring and associated early warnings constitute important research topics but currently only a few papers about sinkhole prediction can be found in this paper an experience of sinkhole monitoring and early warning with gb insar is described the latter is a highly precise instrument that is able to produce displacement maps with metric spatial resolution the described activities were carried out on elba island central italy where karstified limestone set off the occurrence of nine sinkholes since 2008 all within less than 3000 m2 causing major damage to an important road and many indirect losses in 1 year of monitoring two deforming areas were detected and the point where a sinkhole was about to propagate to the street level was predicted thus permitting the preventive closure of the road the deformation area was larger than the hole generated by the sinkhole thus showing a subsidence that continued for a prolonged time even after the cavity was filled up the occurrence of a 1 5 m wide sinkhole undetected by the gb insar also showed the lower detection limit of the instrument

geochemical evidence of the renewal of volcanic activity inferred from co2 soil and so2 plume fluxes the 2007 stromboli eruption italy on 27 february 2007 a new eruption occurred on stromboli which lasted until 2 april it was characterized by effusive activity on the sciara del fuoco and by a paroxysmal event 15 march this crisis represented an opportunity for us to refine the model that had been developed previously 2002 2003 eruption and to improve our understanding of the relationship between the magmatic dynamics of the volcano and the geochemical variations in the fluids in particular the evaluation of the dynamic equilibrium between the volatiles co2 and so2 released from the magma and the corresponding fluids discharged from the summit area allowed us to evaluate the level of criticality of the volcanic activity one of the major accomplishments of this study is a 4 year database of summit soil co2 flux on the basis of which we define the thresholds low medium high for this parameter that are empirically based on the natural volcanological evolution of stromboli the so2 fluxes of the degassing plume and the co2 fluxes emitted from the soil at pizzo sopra la fossa are also presented it is noteworthy that geochemical signals of volcanic unrest have been clearly identified before during and after the effusive activity these signals were found almost simultaneously in the degassing plume so2 flux and in soil degassing co2 flux at the summit although the two degassing processes are shown to be clearly different the interpretation of the results will be useful for future volcanic surveillance at stromboli

integration between ground based and satellite sar data in landslide mapping the san fratello case study abstract the potential use of the integration of psi persistent scatterer interferometry and gb insar ground based synthetic aperture radar interferometry for landslide hazard mitigation was evaluated for mapping and monitoring activities of the san fratello landslide sicily italy intense and exceptional rainfall events are the main factors that triggered several slope movements in the study area which is susceptible to landslides because of its steep slopes and silty clayey sedimentary cover in the last three centuries the town of san fratello was affected by three large landslides developed in different periods the oldest one occurred in 1754 damaging the northeastern sector of the town in 1922 a large landslide completely destroyed a wide area in the western hillside of the town in this paper the attention is focussed on the most recent landslide that occurred on 14 february 2010 in this case the phenomenon produced the failure of a large sector of the eastern hillside causing severe damages to buildings and infrastructures in particular several slow moving rotational and translational slides occurred in the area making it suitable to monitor ground instability through different insar techniques ps insar permanent scatterers sar interferometry techniques using ers 1 ers 2 envisat radarsat 1 and cosmo skymed sar images were applied to analyze ground displacements during pre and post event phases moreover during the post event phase in march 2010 a gb insar system able to acquire data continuously every 14 min was installed collecting ground displacement maps for a period of about three years until march 2013 through the integration of space borne and ground based data sets ground deformation velocity maps were obtained providing a more accurate delimitation of the february 2010 landslide boundary with respect to the carried out traditional geomorphological field survey the integration of gb insar and psi techniques proved to be very effective in landslide mapping in the san fratello test site representing a valid scientific support for local authorities and decision makers during the post emergency management

the geological significance of manganese distribution in jurassic cretaceous rocks of the pindos basin peloponnese greece abstract the jurassic mid cretaceous radiolarite series of the pindos zone of the peloponnese is a deep water sediment sequence it comprises jurassic red mudstones siliceous mudstones and ribbon bedded cherts and cretaceous red mudstones siliceous mudstones cherts calc turbidites and terrigenous turbidites bedded manganese ores occur both in cherty calc turbidites and ribbon bedded cherts in order to determine the origin of mn enrichment the transition element geochemistry and mineralogy has been determined for sediment samples from seven representative sections of the radiolarite series representing an along and across strike section of the pindos basin smectite and palygorskite are the principal clay minerals with lesser mica sepiolite and chlorite fe al ratios in jurassic rocks are close to values in continental detritus but increase upwards to the middle cretaceous nevertheless the association of volcanic rocks with jurassic sediments is circumstantial evidence that the minor mn enrichment is the result of hydrothermal processes the hypothesis that high fe al in cretaceous sediments is due to ophiolitic detritus is untenable in the peloponnese where sediment is derived from sources lacking ophiolites the fe enrichment must therefore result from hydrothermal processes which may be related to formation of oceanic crust in the pindos arvi zones mn concentrations are associated with diagenetic cherts at the top of calc turbidites in these settings mn correlates positively with ca and negatively with fe suggesting that the concentration of beds of ore is diagenetic

a ubiquitous low velocity layer at the base of the mantle transition zone global stacks of receiver functions clearly exhibit the upper mantle stratification besides the most prominent seismic discontinuities such as the moho and the 410 and 660 km discontinuities a negative discontinuity is detected at a depth of 600 km indicating a low velocity layer at the base of the mantle transition zone the slant slack technique helps to identify the primary conversions from the multiple reverberations presence of the negative 600 km discontinuity underneath both continent and ocean island stations where the crustal thickness significantly differs also precludes the possible cause of crustal reverberations we conclude that the negative 600 km discontinuity could be a global feature possibly resulted from accumulation of ancient subducted oceanic crust the x discontinuity at 300 km depth is also observed in our global stacks which can be explained by the coesite stishovite phase transformation

sea level changes an integrated approach sea level changes an integrated approach in october 1985 sepm sponsored a four day conference entitled sea level changes an integrated approach the purpose of the conference was to provide a forum for an interdisciplinary exchange of ideas on sea level changes and to provide an opportunity for integrating various types of evidence in approaching unresolved issues the conference was successful in bringing together scientists from industry academia and government representing all of the major geosciences disciplines presentations of many new papers plus significant releases of data that were previously held proprietary provided fertile ground for discussion this much cited volume represents the best of the material presented at the conference includes the early vail chart

partitioned tectonic shortening with emphasis on outcrop scale folding and flattening pindos fold and thrust belt peloponnese greece shortening estimates for fold thrust belts seldom take into consideration outcrop scale folding especially folding related to prethrusting layer parallel shortening lps and flattening the pindo

the 15 march 2007 explosive crisis at stromboli volcano italy assessing physical parameters through a multidisciplinary approach basaltic volcanoes are dominated by lava emission and mild explosive activity nevertheless many basaltic systems exhibit from time to time poorly documented and little understood violent explosions a short lived multiblast explosive crisis paroxysmal explosion occurred on 15 march 2007 during an effusive eruptive crisis at stromboli italy the explosive crisis which started at 20 38 14 ut had a total duration of 5 min the combined use of multiparametric data collected by the permanent instrumental networks seismic acoustic and thermal records and a field survey carried out immediately after the event enabled us to constrain the eruptive dynamics and quantify physical parameters the eruption consisted of three major pulses in the first lithic blocks and ash were ejected at speeds of 100 155 m s and 130 210 m s respectively the high solid load of the eruptive jet resulted in the partial collapse of the column with the formation of a small volume pyroclastic density current the second 12 s long pulse emitted 2 2 2 7 107 kg of tephra mass discharge rate 1 9 2 3 106 kg s forming a 3 km high convective plume dispersing tephra up to the west coast and a dilute density current with limited dispersal downslope of the craters a final 30 s long phase formed a scoria flow with a volume of 1 5 1 7 104 m3 mass discharge rate 5 9 6 7 105 kg s a total runout of 200 m and a velocity of 45 m s the total gas volume involved in the explosion was 1 3 1 9 104 m3 with an initial overpressure of 7 9 0 4 mpa we compared the 15 march 2007 event with historical paroxysms in particular with that of 5 april 2003 which was remarkably similar

broadband array observations of the 300 km seismic discontinuity 1 intermittent seismic discontinuities near 250 300 km depth beneath south america and the pacific basin are detected with high resolution seismic array methods that use ss and pp precursors recorded at the high lava plains seismic experiment and the earthscope transportable array the transformation of coesite to stishovite in an eclogite rich mantle composition produces a seismic discontinuity near 300 km depth lateral changes in basalt fraction of the upper mantle will thus produce an intermittent seismic discontinuity the sensitivity of the precursors to intermittent seismic structure is addressed using an axisymmetric finite difference model of wave propagation in the mantle these numerical experiments find that the precursors are sensitive to structures 500 km in lateral extent and that the observations of this discontinuity are plausibly tied to lateral variations in basaltic composition of the upper mantle related to dynamics such as plumes and subduction

a case history of paroxysmal explosion at stromboli timing and dynamics of the april 5 2003 event abstract on april 5 2003 stromboli volcano italy produced the most violent explosion of the past 50 years the event was exceptionally well documented thanks to the presence on the island of several scientists and a large number of instruments deployed over the preceding months to monitor the effusive eruption that began in december 2002 integration of visual documentation deposit features and geophysical data allowed an accurate reconstruction of the explosive event and its dynamics the eruption consisted of a 8 min long explosive event which evolved through four phases whose timing was precisely recorded by an infrared thermometer located about 450 m from the summit crater phases 2 and 3 lasted 39 and 42 s respectively both had an impulsive character were responsible for ejecting almost the entire mass of the pyroclastic products phases 1 and 4 represented respectively a short lived precursory event and a waning tale during phase 2 meter sized ballistic blocks were launched with velocities of 170 m s to altitudes of up to 1400 m above the craters these fell on the volcano flanks and on the village of ginostra about 2 km distant from the vent a vertical jet rose above the craters which developed to feed a convective plume that reached a height of up to 4 km the calculated mass of the phase 2 fallout deposit and mass discharge rate were 1 1 1 4 108 kg and 2 8 3 6 106 kg s respectively during phase 3 a scoria flow deposit with an estimated volume of 0 9 1 1 104 m3 was erupted from the same vent that fed the ongoing sustained lava flow the average mass discharge rate for this phase was 2 5 3 1 105 kg s products emitted during phases 2 and 3 consisted of lithic and fresh magmatic material in similar proportions the juvenile fraction consisted of a deep originated almost aphyric highly vesicular pumice mingled with a shallow derived crystal rich moderately vesicular scoria similarities with the eruption dynamics of other historical paroxysms at stromboli makes the april 5 2003 explosion representative of these highly energetic events that constitute the most hazardous volcanic phenomena at stromboli volcano

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

the 2002 2003 eruption of stromboli italy evaluation of the volcanic activity by means of continuous monitoring of soil temperature co2 flux and meteorological parameters 1 from december 2002 to july 2003 stromboli volcano was characterized by a new effusive stage of eruption after a period of extraordinary strombolian activity signals recorded in two continuous monitoring stations during the eruption which have already been presented in very recent papers evidenced anomalies in the co2 flux just before the onset of the eruption a more detailed analysis carried out on the data subset acquired during the eruption integrated by daily field observations of the scientific personnel working at the volcanological observatory in stromboli showed that co2 flux and soil temperature are strictly related to volcanic events furthermore the relative minima and maxima of the two parameters showed a strong correlation with wind speed and direction this fact was especially true at the summit station whereas at the coastal sites seasonal and meteorological effects masked the volcanic signal the analysis of the wind data particularly the relationships between wind speed and direction air and soil temperature and local circulation of atmospheric air masses revealed that during the eruption in the summit area of stromboli air movements were not only related to atmospheric circulation but were also significantly affected and in certain cases caused by volcanic activity this conclusion was reached by observing several anomalies such as the discrepancies in the wind direction between the two stations higher air temperatures at the summit site and inversion of direction for wind before and after the reopening of the conduit in a major explosion on 5 april 2003 the relationships found between volcanic activity soil temperatures co2 fluxes and wind speed and direction indicate that soil temperature measurements in an open conduit volcano such as in this case could be used to monitor the level of volcanic activity along with co2 flux furthermore the possible volcanic origin of a peculiar type of air circulation identified in the summit area of stromboli suggests that the separation between volcanic and atmospheric signals might not be obvious requiring monitoring over a wide area rather than a single location

multiple sector collapses at stromboli volcano italy how they work this paper demonstrates that four large sector collapses have affected the nw flank of the stromboli volcano in the past 13 ka alternating with growth phases in order to contribute to the evaluation of the critical conditions which trigger lateral collapses a reconstruction of the geometry of each collapse of the volcano edifice in the four stages that preceded the relative collapse events is also presented and a computation of the landslide volume this reconstruction is based on new field data plotted in three dimensions prior to the initial 13 ka collapse the volcano was 1125 100 m high above sea level the collapse had a volume of 2 23 0 87 km3 whereas the pre collapse volcano volume was 218 8 7 7 km3 the next edifice that failed was 900 70 m high a s l the collapse volume was 1 0 54 km3 with a precollapse volcano volume of 201 4 5 4 km3 the edifice then grew to 1000 60 m a s l the third collapse had a volume of 1 08 0 39 km3 and occurred within a volcano with a volume of 209 1 4 6 km3 this was followed by a new growth phase followed by the last collapse with a volume of 0 73 0 22 km3 the volcano volume was about the same as the present one the present active crater zone is at 780 m a s l in the first three collapses sliding surfaces cut the main magma conduit in the last collapse the upper scarp coincided with the conduit location dyking along a main ne trending weakness zone across the volcano summit exerted a lateral force for collapse inception the decrease of the landslide volumes with the age and the concentric scarps of the four collapses suggest that the younger sliding planes tended to become more superficial and to decrease the areal extent this is interpreted as due to a successively weaker eruptive products from dominantly lavas to dominantly pyroclastics and b the feedback effects between collapses and dykes that injected along the lateral segments of the first collapse slide plane

ubiquitous low velocity layer atop the 410 km discontinuity in the northern rocky mountains receiver functions from three 30 station iris passcal small aperture arrays 2 15 km station spacing operated for 10 months each in the northern rocky mountains show a ubiquitous negative polarity p to s conversion just preceding the 410 km discontinuity arrival data from the three arrays were sorted into nw se and sw back azimuth quadrants and stacked to form nine quadrant stacks remarkably the negative polarity arrival npa is apparent in 8 of the 9 quadrant stacks with 7 of the 8 having well correlated waveforms each quadrant stack also contains clear p to s conversions from the 410 and 660 km discontinuities moveout analysis shows that all the major phases display the correct moveout for forward scattered p s phases the waveshapes for the seven similar npa 410 km discontinuity arrivals are modeled with a five parameter double gradient slab model that is parameterized as follows a top gradient thickness and shear velocity decrease a constant velocity layer bottom gradient thickness and shear velocity increase model misfit is assessed via a grid search over the model space using a reflectivity code to calculate synthetic seismograms model likelihood is determined by calculating 1 and 2 d marginal probability density functions pdf for the five parameters the 1 d marginals display a range of peak values although significant overlap is observed for the top gradient thickness and its associated velocity decrement from the peak value of the summary pdf we find the top velocity gradient to be sharp 6 4 km and the shear velocity decrement to be large 8 9 vs defining an effective thickness of the low velocity layer as the mean layer thickness plus half the mean gradient thicknesses the 410 low velocity layer thickness is found to be 22 km a review of changes in the physical state required to match our new 410 lvl constraints suggests that the water filter model remains an operative hypothesis to test

from obduction to continental collision new data from central greece the aim of this paper is to contribute to deciphering the evolutionary history of the hellenides by the study of a large sector of the chain located between the front of the ophiolitic units and the external zones classically attributed to the continental margin of adria in particular the tectonic units located in boeotia a key area located in central greece at the boundary between the internal and external hellenides were studied from structural stratigraphic and biostratigraphic points of view addressing the main debated aspects concerning the origin of the ophiolite nappe s the tectonic evolution of the hellenic orogen was revised with a particular emphasis on the period between obduction and continental collision new findings were compared with consolidated data concerning the main metamorphic events recorded in the more internal hellenides geochemistry and age of the ophiolites and main stratigraphic constraints obtained in other sectors of the belt finally a new reconstruction of the tectonic evolution of this area was introduced and in the context of the dispute concerning the origin of the ophiolitic belts as a possible record of multiple oceanic basins we put forward for consideration a single ocean tectonic model spanning from triassic up to tertiary times and valid for the whole hellenic albanian sector

a new classification of the turkish terranes and sutures and its implication for the paleotectonic history of the region abstract the turkish part of the tethyan realm is represented by a series of terranes juxtaposed through alpine convergent movements and separated by complex suture zones different terranes can be defined and characterized by their dominant geological background the pontides domain represents a segment of the former active margin of eurasia where back arc basins opened in the triassic and separated the sakarya terrane from neighbouring regions sakarya was re accreted to laurasia through the balkanic mid cretaceous orogenic event that also affected the rhodope and strandja zones the whole region from the balkans to the caucasus was then affected by a reversal of subduction and creation of a late cretaceous arc before collision with the anatolian domain in the eocene if the anatolian terrane underwent an evolution similar to sakarya during the late paleozoic and early triassic times both terranes had a diverging history during and after the eo cimmerian collision north of sakarya the kure back arc was closed during the jurassic whereas north of the anatolian domain the back arc type oceans did not close before the late cretaceous during the cretaceous both domains were affected by ophiolite obduction but in very different ways north directed diachronous middle to late cretaceous melange obduction on the jurassic sakarya passive margin senonian synchronous southward obduction on the triassic passive margin of anatolia from this it appears that the izmir ankara suture currently separating both terranes is composite and that the passive margin of sakarya is not the conjugate margin of anatolia to the south the cimmerian taurus domain together with the beydaglari domain part of the larger greater apulian terrane were detached from north gondwana in the permian during the opening of the neotethys east mediterranean basin the drifting cimmerian blocks entered into a soft collision with the anatolian and related terranes in the eo cimmerian orogenic phase late triassic thus suturing the paleotethys at that time the taurus plate developed foreland type basins filled with flysch molasse deposits that locally overstepped the lower plate taurus terrane and were deposited in the opening neotethys to the south these olistostromal deposits are characterized by pelagic carboniferous and permian material from the paleotethys suture zone found in the mersin melange the latter as well as the antalya and mamonia domains are represented by a series of exotic units now found south of the main taurus range part of the mersin exotic material was clearly derived from the former north anatolian passive margin huglu type series and re displaced during the paleogene this led us to propose a plate tectonic model where the anatolian ophiolitic front is linked up with the samail baer bassit obduction front found along the arabian margin the obduction front was indented by the anatolian promontory whose eastern end was partially subducted continued slab roll back of the neotethys allowed anatolian exotics to continue their course southwestward until their emplacement along the taurus southern margin mersin and up to the beydaglari promontory antaya mamonia in the latest cretaceous paleocene the supra subduction ocean opening at the back of the obduction front troodos type ocean was finally closed by eocene north south shortening between africa and eurasia this brought close to each other cretaceous ophiolites derived from the north of anatolia and those obducted on the arabian promontory the latter were sealed by a maastrichtian platform and locally never affected by alpine tectonism whereas those located on the eastern anatolian plate are strongly deformed and metamorphosed and affected by eocene arc magmatism these observations help to reconstruct the larger frame of the central tethyan realm geodynamic evolution

seismic imaging of upper mantle structure with new evidence for a 520 km discontinuity stacked images of long period seismic data reveal many phases some not previously observed which are caused by reflections and conversions at discontinuities in the earth s upper mantle these images support the existence of discontinuities at 410 520 and 660km depth but no evidence is found for a significant interface at 220 km

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

unusually large magmatic co2 gas emissions prior to a basaltic paroxysm 1 the low intensity activity of basaltic volcanoes is occasionally interrupted by short lived but energetic explosions which whilst frequently observed are amongst the most enigmatic volcanic events in nature the combination of poorly understood and deep challenging to measure source processes make such events currently impossible to forecast here we report increases in quiescent degassing co2 emissions 10 000 t day prior to a powerful explosive event on stromboli volcano on 15 march 2007 we interpret such large co2 flux as being sourced by passive gas leakage from a deeply 4 km stored magma whose depressurization possibly caused by the onset of an effusive eruption on 28 february 2007 was the explosion trigger our observations suggest that continuous co2 flux monitoring may allow anomalously large explosions to be accurately forecast at basaltic volcanoes

stability of a collapsing volcano stromboli italy limit equilibrium analysis and numerical modelling abstract stromboli is an active island volcano belonging to the aeolian archipelago italy in the last 13 ka it experienced four lateral collapses affecting its northwestern flank with its most recent volcanic crisis december 2002 associated with landslides and related tsunami events this paper presents the first stability analysis of the stromboli volcanic edifice the main input is the geotechnical model of the volcano defined on the basis of stratigraphical lithological material properties and structural data collected from in situ surveys and laboratory tests two dimensional stability analysis was performed by limit equilibrium methods lem and finite difference modelling flac 4 0 code mainly focusing on the subaerial part of stromboli s nw flank sciara del fuoco the variability of the safety factor was studied by deterministic sensitivity and probabilistic analysis focusing on the effect of external forces such as magma pressure and seismicity as potential triggering mechanisms of lateral collapse the lem analyses were developed considering a maximum depth of 150 350 m for the sliding surface to which correspond collapse volumes of 95 000 185 000 m 3 m respectively the study shows that without external forces the investigated rock mass is stable and that the tectonic seismicity of the area alone does not destabilize the studied slope on the contrary magma pressure in dykes can represent a destabilizing factor numerical modelling results are concordant with those from lem in addition the simulation reveals that deformations and superficial landslides preannounce and contribute to retrogressive plasticization and maybe to failure surface deepening shallow submarine landslides represent a possible triggering mechanism and the landslide events of 30 december 2002 consistently fit the simulated evolution flac has revealed to be a useful tool for modelling such a complex system it allowed to calibrate the response of the geotechnical model test the validity of the assumptions simulate the stress strain evolution and prepare a possible model for future scenarios

elastic properties of hydrous ringwoodite γ phase in mg2sio4 abstract single crystal elastic properties of hydrous ringwoodite are reported for samples that were synthesized at 19 gpa and 1300 c the mg si ratio is determined to be 1 95 by epma which is slightly lower than that of ideal anhydrous ringwoodite the h 2 o content determined by sims is 2 2 wt resulting in the stoichiometry mg 1 89 si 0 97 o 4 h 0 33 the lattice parameter a 8 0786 4 a and elastic constants were determined from a single crystal with x ray diffractometry and brillouin scattering spectroscopy the crystal structure is cubic fd3m with a unit cell volume which is 0 51 larger than that of the anhydrous ringwoodite the adiabatic single crystal elastic moduli of hydrous ringwoodite in gpa are c 11 281 6 c 44 117 4 c 12 92 5 the isotropic properties of hydrous ringwoodite are k vrh 155 4 and g vrh 107 3 which are about 16 and 10 smaller than those of anhydrous ringwoodite thus hydrous ringwoodite if present drastically reduces the seismic velocity in the mantle transition zone relative to anhydrous ringwoodite in addition our results show that the anisotropy is enhanced relative to anhydrous ringwoodite using the present results we discuss the 520 km seismic discontinuity in a wet mantle transition zone

studying the 410 km and 660 km discontinuities beneath spain and morocco through detection of p to s conversions this is a contribution of the projects consolider ingenio 2010 topoiberia csd2006 00041 topomed cgl2008 03474 e bte rifsis cgl2009 09727 cgl2012 31472 and p09 rnm 5100 l bonatto benefits from a ph d jaepredoc csic grant

the rheology of crystal bearing basaltic magmas from stromboli and etna abstract our ability to forecast volcanic hazards at active volcanoes stems from our knowledge of parameters affecting eruption dynamics persistent activity displayed by basaltic volcanic systems such as etna and stromboli is governed mainly by the textural evolution and rheological properties of eruptive products here we investigate the high temperature 1131 c

characterizing high energy explosive eruptions at stromboli volcano using multidisciplinary data an example from the 9 january 2005 explosion abstract stromboli is well known for its persistent normal explosive activity consisting of intermittent mild to moderate strombolian explosions that typically occur every 10 20 min all tephras erupted during this activity usually fall back into the crater terrace and consist of volatile poor scoriae fed by highly porphyritic hp magma more occasionally large explosions or paroxysms eject a greater quantity of tephra mainly consisting of hp scoriae and pumice clasts of low porphyritic lp magma but also including large lithic blocks in addition to this activity between 2004 and 2006 high energy explosions displaying an intermediate eruptive style between that of normal and paroxysmal explosions in terms of column height duration and tephra dispersal were observed to occur at a frequency of one to eight events per year while many volcanological geochemical and geophysical studies have focused in the last few years on the two end members of activity i e normal or paroxysmal a detailed investigation on these intermediate types of events has not been carried out yet here we report of a study on the 9 january 2005 explosion one of the high energy explosions during which the main fountaining phase lasted nearly a minute causing ejection of coarse bombs up to a height of 120 m and of ash and lapilli to 200 m an accompanying ash plume rose up to 500 m at the end of the explosion we present a multidisciplinary approach that integrates the results from analysis of live camera images with compositional and textural characterization of the erupted products major element composition of glassy groundmass and 3d views of textures in the erupted scoriae support the hypothesis based on volcanological observations that this explosion falls between normal and paroxysmal activity for which we use the term intermediate by comparing the video camera images of the 9 january 2005 explosion with volcanological features of other high energy explosions that occurred at stromboli between june 2004 and october 2006 we find that three additional events can be considered intermediate explosions suggesting that this type of activity may be fairly common on this volcano the results of this study although preliminary given our limited dataset clearly indicate that the methodology used here can be successfully applied to better define the range of eruptive styles typifying the normal explosive activity potentially improving our capability of eruption forecasting and assessing volcanic hazard at stromboli

receiver function imaging of upper mantle complexity beneath the pacific northwest united states abstract small scale topographic variations on the upper mantle seismic discontinuities provide important constraints on the thermal influences of upwellings and downwellings in geodynamically complex regions subduction of the juan de fuca plate and other tectonic processes dominating the pacific northwest united states in the cenozoic involve massive thermal flux that likely result in an upper mantle that has strong 3 d temperature variations we address the interaction of such processes in the region using receiver functions to image the upper mantle seismic discontinuities at 410 and 660 km we utilized over 15 000 high quality receiver functions gathered from 294 teleseismic earthquakes recorded at 277 regional broadband seismic stations primarily those of the earthscope usarray transportable array we find the average depths of the discontinuities to be 412 km and 658 km respectively with no obvious 520 km discontinuity detected the peak to peak range is greater on the 410 than the 660 suggesting the possibility of more significant regional dynamic processes at upper mantle depths our results are not consistent with a mantle plume below central oregon in the high lava plains region our observation of a thinner transition zone beneath the western snake river plain region however is consistent with a regional increase in mantle temperatures perhaps due to either asthenospheric flow from beneath and around the southern edge of the juan de fuca plate or to vertical flow in the form of regional mantle upwelling related to the snake river plain yellowstone hotspot track further our results are not consistent with a simple subducting juan de fuca slab morphology but rather suggest similar levels of significant complexity in slab structure found by recent regional tomographic studies we find evidence for a thickened and therefore cooler mantle transition zone beneath the wallowa idaho batholith region consistent with tomographic models which suggest broad scale increased seismic velocities to transition zone depths we speculate that this region may be the location of mantle downwelling at larger scales than previously proposed

the 2014 effusive eruption at stromboli volcano italy inferences from soil co2 flux and 3he 4he ratio in thermal waters a new eruption started at stromboli on 6 august 2014 which had been preceded by 2 months of increased strombolian activity and several lava overflows from the craters the eruption was characterized by a lava effusion in sciara del fuoco from a fracture at 650 m above sea level that lasted until 13 17 november here we present the first geochemical observations of this eruption based on the soil co2 flux in the summit area and on 3he 4he ratios in the thermal waters near stromboli village we infer that this eruption was triggered by the gradual replenishment of the feeding system by a co2 and 3he rich magma at the end of 2013 and after june 2014 suggested by the increase in 3he 4he ratio before eruption which reached its highest value since 2007 we thus infer that this eruption was unusual and we finally speculate on the evolutionary scenario of posteruption

topography of the transition zone seismic discontinuities phase transformations in mantle mineralogies probably cause the transition zone seismic discontinuities nominally at 410 520 and 660 km depth thermodynamic principles govern phase transformations making them sensitive to changes in the mantle s ambient conditions through the thermodynamic response changes in temperature or composition shift the transformation to a different pressure creating topography on a level discontinuity with this use as an exploratory tool for the mantle in mind we review the basic seismological and phase equilibrium concepts underlying the detection and interpretation of the seismic wave arrivals associated with the transition zone discontinuities reviewing the evidence for and against the phase transition model we conclude that it is viable and describe how discontinuities have been and can be used to probe the physical and chemical state of the transition zone

radiative heat power at stromboli volcano during 2000 2011 twelve years of modis observations abstract twelve years of night time modis moderate resolution imaging spectroradiometer observations has been analysed to detect and quantify the radiative heat power emitted by stromboli volcano from march 2000 to september 2011 using an accurate background subtraction of the modis signal at 4 m we were able to discriminate two main regimes of thermal radiation related to different levels of volcanic activity effusive eruptions occurred on december 28 2002 and february 27 2007 radiated at an average of 186 mw with a frequency of alert detection of 50 95 conversely during the typical strombolian activity an average of 9 mw is radiated with a frequency of alert detection of 0 45 although during the effusive eruptions the radiative power is basically controlled by the lava discharge rate our results suggest that during non effusive periods strombolian regime both the intensity and the frequency of modis alerts are controlled by the height of the magmatic column feeding the activity at the surface in particular we found that a radiative power of 50 mw corresponds to a high magma column which is exposed in the vent area at the same rate in which the deeper gas rich magma is typically supplied within the feeding system of stromboli 0 3 m3 s 1 in this condition the magmatic system approaches steady state regimes above this threshold a transition from strombolian to effusive regimes may occur as shown by the detection of 50 mw 8 10 days before the onset of both the last two major flank eruptions these values were reached after 1 2 months of gradual increase of the radiative power which was likely associated the rising of the magma column within the shallowest portion of the conduit in addition our data suggest that over the years 2000 2011 several cycles of rise and fall of the magma column have occurred which however did not culminate into an effusive eruption but only into recurrent episodes of sustained spattering or fountaining and summit overflows these fluctuations has substantially increased in frequency and intensity after the 2007 eruption thus suggesting that this event has perturbed in some way the shallow plumbing system of stromboli we stress that the detection of a radiative power higher than 50 mw is a clear evidence of a very high magma column which may prelude the onset of an effusive eruption and or periods of sustained vent activity in conclusion we suggest that systematic analysis of modis data can be used to detect variations in the intensity of strombolian activity and may considerably improve volcano surveillance at stromboli as well as at other open system volcanoes

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

synthesis of the tectonic sedimentary evolution of the mesozoic early cenozoic pindos ocean evidence from the nw peloponnese greece

stagnant slab a review a stagnant slab is a subducted slab of oceanic lithosphere subhorizontally deflected above across or below the 660 km discontinuity this phenomenon has now been widely recognized beneath subduction zones around the circum pacific and in the mediterranean collaboration of seismic and electromagnetic observations mineral physics measurements and geodynamic modeling has begun to provide a consistent picture of stagnant slab

high speed imaging of strombolian explosions the ejection velocity of pyroclasts explosive volcanic eruptions are defined as the violent ejection of gas and hot fragments from a vent in the earth s crust knowledge of ejection velocity is crucial for understanding and modeling relevant physical processes of an eruption and yet direct measurements are still a difficult task with largely variable results here we apply pioneering high speed imaging to measure the ejection velocity of pyroclasts from strombolian explosive eruptions with an unparalleled temporal resolution measured supersonic velocities up to 405 m s are twice higher than previously reported for such eruptions individual strombolian explosions include multiple sub second lasting ejection pulses characterized by an exponential decay of velocity when fitted with an empirical model from shock tube experiments literature this decay allows constraining the length of the pressurized gas pockets responsible for the ejection pulses these results directly impact eruption modeling and related hazard assessment as well as the interpretation of geophysical signals from monitoring networks

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

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

an analytical model for gas overpressure in slug driven explosions insights into strombolian volcanic eruptions strombolian eruptions common at basaltic volcanoes are mildly explosive events that are driven by a large bubble of magmatic gas a slug rising up the conduit and bursting at the surface gas overpressure within the bursting slug governs explosion dynamics and vigor and is the main factor controlling associated acoustic and seismic signals we present a theoretical investigation of slug overpressure based on magma static and geometric considerations and develop a set of equations that can be used to calculate the overpressure in a slug when it bursts slug length at burst and the depth at which the burst process begins we find that burst overpressure is controlled by two dimensionless parameters v which represents the amount of gas in the slug and a which represents the thickness of the film of magma that falls around the rising slug burst overpressure increases nonlinearly as v and a increase we consider two eruptive scenarios 1 the standard model in which magma remains confined to the vent during slug expansion and 2 the overflow model in which slug expansion is associated with lava effusion as occasionally observed in the field we find that slug overpressure is higher for the overflow model by a factor of 1 2 2 4 applying our model to typical strombolian eruptions at stromboli we find that the transition from passive degassing to explosive bursting occurs for slugs with volume 24 230 m 3 depending on magma viscosity and conduit diameter and that at burst a typical strombolian slug with a volume of 100 1000 m 3 has an internal gas pressure of 1 5 bars and a length of 13 120 m we compare model predictions with field data from stromboli for low energy puffers mildly explosive strombolian eruptions and the violently explosive 5 april 2003 paroxysm we find that model predictions are consistent with field observations across this broad spectrum of eruptive styles suggesting a common slug driven mechanism we propose that paroxysms are driven by unusually large slugs large v

age and significance of upper cretaceous siliciclastic turbidites in the central pindos mountains greece a significant 5 to 30 metre thick interval of siliciclastic turbidites forming the first flysch is present in the deep water succession of the pindos zone nannofossil investigations in the central parts of the pindos mountains of mainland greece indicate an assemblage of the marthasterites furcatus zone cc13 the presence of m furcatus together with common quadrum gartneri suggests that the turbidites were deposited mainly during the middle to upper part of the late turonian the siliciclastic turbidites are interpreted as deposits of a lowstand fan as a result of a pronounced short time eustatic sea level drop in the late turonian

preeruptive inflation and surface interferometric coherence characteristics revealed by satellite radar interferometry at makushin volcano alaska 1993 2000 1 pilot reports in january 1995 and geologic field observations from the summer of 1996 indicate that a relatively small explosive eruption of makushin one of the more frequently active volcanoes in the aleutian arc of alaska occurred on 30 january 1995 several independent radar interferograms that each span the time period from october 1993 to september 1995 show evidence of 7 cm of uplift centered on the volcano s east flank which we interpret as preeruptive inflation of a 7 km deep magma source v 0 022 km3 subsequent interferograms for 1995 2000 a period that included no reported eruptive activity show no evidence of additional ground deformation interferometric coherence at c band is found to persist for 3 years or more on lava flow and other rocky surfaces covered with short grass and sparsely distributed tall grass and for at least 1 year on most pyroclastic deposits on lava flow and rocky surfaces with dense tall grass and on alluvium coherence lasts for a few months snow and ice surfaces lose coherence within a few days this extended timeframe of coherence over a variety of surface materials makes c band radar interferometry an effective tool for studying volcano deformation in alaska and other similar high latitude regions

review of ten years of volcano deformations recorded by the ground based insar monitoring system at stromboli volcano a tool to mitigate volcano flank dynamics and intense volcanic activity abstract stromboli volcano southern italy is one of the most monitored volcano in the world with a surveillance network that includes a permanently sited ground based sar interferometer gbinsar this work is the review of the gbinsar data gained from the last decade of monitoring activity the analysis of the entire dataset of gbinsar measurements allowed the assessment of the deformation field of the northern part of the summit crater area and the sciara del fuoco depression in detail the main displacements recognized can be related to different factors 1 the inflation deflation respectively immediately before and after each new effusive event 2 the bulging of localized sectors of the volcano involved in the vent opening 3 the gravitational sliding of the sciara del fuoco infill 4 the movement of lava flows accelerations in this sector are related to sheet intrusions while the possibility of vent opening associated with small sliding or catastrophic flank failure are related to highly overpressurized sheets able to produce high displacement rate in the sciara del fuoco in the summit crater area the increases in the displacement rate are related to the pressurization of the shallow conduit system as the consequence of the variation in the magma level magmastatic pressure or to the lateral magma migration lateral conduit expansion or dike intrusion in response to the increase of the overpressure component fluctuations in the displacement rate in the summit crater area can be related to the magma overturning within the conduit with the increases in displacement rate during the upwelling of less dense magma while displacement rate decreases as the degassed magma column is pushed out from the conduit lava flows or overflows instead the decrease in the displacement rate without coeval lava outpouring could be related to the sink of the degassed magma due to density contrast between the gas poor and the gas charged magmas using the displacement rate in the summit crater area as a proxy for the variation in the pressure condition in conduit both magmastatic and overpressure components thresholds for the crises characterized by the occurrence of overflows eventually associated with major explosions and flank effusions eventually associated with paroxysmal explosions are identified small conduit overpressure will produce overflows sometimes associated with crater rim collapses while large magma overpressure will laterally expand the conduit forming ne sw striking sheets feeding eruptive vents at the base of the summit crater area and within the sciara del fuoco generating conditions of instability that can evolve into catastrophic collapse of the instable flank

monitoring crater wall collapse at active volcanoes a study of the 12 january 2013 event at stromboli crater wall collapses are fairly frequent at active volcanoes and they are normally studied through the analysis of their deposits in this paper we present an analysis of the 12 january 2013 crater wall collapse occurring at stromboli volcano investigated by means of a monitoring network comprising visible and infrared webcams and a ground based interferometric synthetic aperture radar the network revealed the triggering mechanisms of the collapse which are comparable to the events that heralded the previous effusive eruptions in 1985 2002 2007 and 2014 the collapse occurred during a period of inflation of the summit cone and was preceded by increasing explosive activity and the enlargement of the crater weakness of the crater wall increasing magmastatic pressure within the upper conduit induced by ascending magma and mechanical erosion caused by vent opening at the base of the crater wall and by lava fingering are considered responsible for triggering the collapse on 12 january 2013 at stromboli we suggest that the combination of these factors might be a general mechanism to generate crater wall collapse at active volcanoes

tracking morphological changes and slope instability using spaceborne and ground based sar data abstract stromboli aeolian archipelago italy is an active volcano that is frequently affected by moderate to large mass wasting which has occasionally triggered tsunamis with the aim of understanding the relationship between the geomorphologic evolution and slope instability of stromboli remote sensing information from space born synthetic aperture radar sar change detection and interferometry insar and ground based insar gbinsar was compared with field observations and morphological analyses ground reflectivity and squeesar an insar algorithm for surface deformation monitoring displacement measurements from x band cosmo skymed satellites csk were analysed together with displacement measurements from a permanent sited ku band gbinsar system remote sensing results were compared with a preliminary morphological analysis of the sciara del fuoco sdf steep volcanic flank which was carried out using a high resolution digital elevation model dem finally field observations supported by infrared thermographic surveys irt allowed the interpretation and validation of remote sensing data the analysis of the entire dataset collected between january 2010 and december 2014 covers a period characterized by a low intensity of strombolian activity this period was punctuated by the occurrence of lava overflows occurring from the crater terrace evolving downslope toward sdf and flank eruptions such as the 2014 event the amplitude of the csk images collected between february 22nd 2010 and december 18th 2014 highlights that during periods characterized by low intensity strombolian activity the production of materials ejected from the crater terrace towards the sdf is generally low and erosion is the prevailing process mainly affecting the central sector of the sdf csk squeesar and gbinsar data allowed the identification of low displacements in the sdf except for high displacement rates up to 1 5 mm h that were measured following both lava delta formation after the 2007 eruption and the lava overflows of 2010 and 2011 after the emplacement of the 2014 lava field high displacements in the central and northern portions of the sdf were recorded by the gbinsar device whereas the spaceborne data were unable to detect these rapid movements a comparison between irt images and gbinsar derived displacement maps acquired during the same time interval revealed that the observed displacements along the sdf were related to the crumbling of newly emplaced 2014 lava and of its external breccia detected slope instability after the 2014 flank eruption was related to lava accumulation on the sdf and to the difference in the material underlying the 2014 lava flow i lava flows and breccia layers related to the 2002 03 and 2007 lava flow fields in the northern sdf sector and ii loose volcaniclastic deposits in the central part of the sdf this work emphasizes the importance of smart integration of spaceborne sar derived hazard information with permanent sited operational monitoring by gbinsar devices to detect areas impacted by mass wasting and volcanic activity

recycling and re hydration of degassed magma inducing transient dissolution crystallization events at stromboli italy abstract intrusive degassing and recycling of degassed and dense magma at depth have been proposed for a long time at stromboli the brief explosive event that occurred at the summit craters on 9 january 2005 threw out bombs and lapilli that could be good candidates to illustrate recycling of shallow degassed magma at depth we present an extensive data set on both the textures and the mineral bulk rock and glassy matrix chemistry of the 9 jan products the latter have the common shoshonitic basaltic bulk composition of lavas and scoriae issued from typical strombolian activity in contrast they differ by the heterogeneous chemistry of their matrix glasses and their crystal textures that testify to crystal dissolution event s just prior magma crystallization upon ascent and eruption comparison between mineral paragenesis of the natural products and experimental phase equilibria suggest water induced magma re equilibration we propose that mineral dissolution is related to water enrichment of the recycled degassed magma via differential gas bubble transfer and to some extents its physical mixing with volatile rich magma blobs however all these features illustrate transient processes even though evidence of mineral dissolution is ubiquitous at stromboli its effect on the bulk magma chemistry is minor because of the subtle interplay between mineral dissolution and crystallization in magmas having comparable bulk chemistry

seismological insight into the kinematics of the 5 april 2003 vulcanian explosion at stromboli volcano southern italy 1 on 5 april 2003 at 07 13 gmt 09 13 local time a violent vulcanian explosion occurred at stromboli volcano at the time of the event an eruptive crisis was ongoing at the volcano with a lava flow outpouring along the sciara del fuoco flank the seismic signals related to the event were recorded by 8 permanent broadband stations and gives information about the eruption kinematics an ultra long period signal period 20 s that we interpret as the effect of the ground tilt on the broadband sensors starts about 4 min before and terminates about 1 min after the explosion on the basis of the radial pattern of tilt directions we conclude that this signal is the effect of the deformation of the volcanic edifice due to the rapid rising of a batch of magma its ejection and the magma column readjustment about 1 min before the explosion we observe an high frequency signal period 0 1 s that we believe to be related to the vesiculation of the rising batch of gas rich magma at 07 13 35 gmt a powerful very long period signal period 2 20 s marking the onset of the explosive fragmentation is recorded this is confirmed by a blast wave following few seconds later the remaining seismic signal more than 3 min shows an higher frequency content being related only to the fall of ballistic ejecta and to landslides along sciara del fuoco we propose the implementation of an early warning system for the short term forecast of such explosions based on the real time automatic detection of the tilt signals preceding such events

geomechanical characterization of the volcaniclastic material involved in the 2002 landslides at stromboli during the 2002 eruption the nw flank of stromboli volcano southern italy experienced large landslides that produced tsunami waves with a maximum runup of 10 m in height this paper focuses on the geomechanical behavior of the loose volcaniclastic layers the weakest component of the deposit forming the volcano flank tests on the coarse grained volcaniclastic soil and on the rock material forming the grains were conducted in dry conditions a feature of the subaerial slope the rock material in spite of its high porosity exhibits relatively high stiffness and strength due to the remarkable continuity of the solid skeleton accordingly the volcaniclastic soil is characterized by high shear strength during shear tests however significant grain crushing occurs which partly explains the nonlinear shear strength envelope and the strain softening associated with contractive behavior grain crushing was also found to affect compressibility and its time dependency investigated under oedometric conditions

mesozoic early tertiary passive margin evolution of the pindos ocean nw peloponnese greece abstract sediment starved deep water slope basin facies of passive margins are of particular interest as they record an interplay of processes including plate tectonic evolution elastic sediment input pelagic deposition and relative sea level change in the past insights have come from deep sea drilling of non emplaced passive margins e g eastern u s a and from preserved sequences within sutured units e g the tethyan and iapetus orogenic belts deep water passive margin successions discussed here represent an excellent example of a relatively sediment starved slope basin setting related to the margin of a microcontinent within the neotethyan ocean in the eastern mediterranean region lithologies are preserved as a series of thrust sheets formed during suturing of the neotethys ocean thrusting resulted in regular in sequence thrusting such that the original slope margin setting can be restored with confidence compared to other tethyan passive continental margin abyssal successions e g oman these sedimentary rocks retain remarkable structural coherence allowing exceptionally detailed three dimensional reconstructions of facies patterns and palaeoceanographic conditions the sedimentary successions belong to the pindos zone of western greece pindos group and comprise deep water carbonate siliciclastic and siliceous rocks ranging in age from late triassic to eocene these rocks accumulated along the western margin of a small neotethyan oceanic basin i e pindos ocean separating the continental blocks of adria apulia and pelagonia the oldest sediments comprise disrupted siliciclastic turbidites largely derived from a metamorphic source to the west and deposited on young oceanic basement from the late triassic to latest maastrichtian variable thicknesses of hemipelagic carbonate and proximal carbonate debris flows accumulated in westerly areas while mainly hemipelagic carbonate and more distal calciturbidite were deposited further east this pattern was interrupted by an extended period of siliceous radiolarian dominated sedimentation during the aalenian to tithonian jurassic from latest maastrichtian onwards progressive closure of the pindos oceanic basin is recorded by a gradual change in sediment composition from dominantly carbonate deposition supplied from the gavrovo tripolitza carbonate platform to the west to siliciclastic sediment derived from the north and east during the eocene oligocene eastward subduction of the pindos ocean resulted in deep sea sedimentary lithologies being detached from their oceanic igneous basement as an accretionary prism and emplaced westwards onto the adjacent carbonate platform ending up as a series of thin skinned thrust sheets

the upper mantle discontinuities correlated or anticorrelated the discontinuities in the earth s upper mantle at 410km and 660km are frequently considered as phase changes which are exothermic and endothermic respectively from this follows that at laterally changing temperatures both discontinuities move in opposing vertical directions that means they are negatively correlated we attempt to test this hypothesis using travel times of seismic waves converted at both discontinuities underneath seismic stations the broadband stations used are located in areas of high e g western us and low heat flow e g central asia sclater et al 1980 we observe a clear positive correlation of the conversion times of both discontinuities which can however be explained with known lateral velocity changes above 410km from the scatter of our data we conclude that the limit of a possibly existing and negatively correlated topography of the two discontinuities is about 28km this is in contrast to recently claimed observations of about 35 km anticorrelated topography in the western pacific revenaugh jordan 1991 stammler kind 1992

computation of seismic profiles from mineral physics the importance of the non olivine components for explaining the 660 km depth discontinuity the recent increasing number of experimental works leads us to review the elastic properties and mineralogical transformations of mantle minerals the updated data set is used to compute seismic profiles for two petrological models along three adiabatic temperature profiles these profiles are chosen to stress out the influence of non olivine minerals on seismic parameters and to represent cold and horizontally averaged temperature profiles of the earth s mantle in a first part starting compositions of pyrolite and piclogite and a single layer convection are assumed the results clearly point out the importance of the non olivine part of the mineralogy two scenarios are found to explain the 660 km depth discontinuity

provenance and distribution of tethyan pelagic and hemipelagic siliceous sediments pindos mountains greece abstract the broad range of time over which ribbon bedded cherts were deposited does not extend into the present marine environment and no ribbon cherts have been recovered from the sea floor by the deep sea drilling project the depositional environment of bedded cherts is difficult to determine but extra silicic impurities in the rock may offer clues about the provenance of the non biogenic component to test the usefulness of relative abundances of the extra silicic components in extracting information on the depositional environment of the chert i analyzed the major element chemistry of chert samples from a broad range of environments including ophiolite associated chert from the franciscan formation of california deep sea chert and porcellanite from the northwest pacific dsdp leg 32 shallow pelagic shelf chert nodules from the chalk of britain continental marginal basin chert from the monterey formation of california and continental marginal basin chert from the pindos zone of greece the ratios feo a12o3 tio2 a12o3 and a1 a1 fe mn were considered in detail the interpretative logic is simple but empirically supported by observations of these ratio values at different depositional environments in the pacific a1 is concentrated most highly in continental material while fe and mn are more concentrated in pelagic sediments feo a12o3 can be used to differentiate between ophiolite associated chert and chert associated only with other sediments tio2 a12o3 is not a useful indicator possibly because of the equalizing effect of widespread eolian transport the a1 a1 fe mn ratio was measured in detail in one stratigraphic section in central continental greece this ratio varied with the type of sediment admixture decreasing in value after the influx of ophiolite debris bearing sediments even when their presence was undetectable in hand sample or under petrographic microscope to help clarify the paleogeography of the main study area the pindos zone and to identify sources and dispersal patterns of extra basinal materials isopach maps of sedimentary facies of the pindos were constructed superimposed directly upon the series of imbricated thrust slices that comprise the pindos zone the maps are at best compressed pictures of the pindos sea floor persistent regional variation of facies thicknesses over time suggests the existence of several smaller depressions surrounded by submarine highs in the pindos basin

effusive to explosive transition during the 2003 eruption of stromboli volcano the persistent explosive activity of stromboli volcano italy ceased in december 2002 and correlated with the onset of a seven month long effusive eruption on the volcano flank from new vents that opened just below the summit craters we intensively monitored this effusive event collecting and interpreting in real time an extensive multiparametric geophysical data set the resulting data synergy allowed detailed insights into the conduit dynamics that drove the eruption and the transition back to the typical strombolian activity we present a direct link between gas flux magma volume flux and seismicity supporting a gas driven model whereby the balance between gas flux and gas overpressure determines whether the system will support effusive or explosive activity this insight enabled us to monitor the migration of the magma column up the conduit and to explain the onset of explosive activity

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

seismic observation of narrow plumes in the oceanic upper mantle 1 we have found seismic evidence for the existence of narrow about 200 km diameter and hot plumes in the upper mantle above the 410 km discontinuity they are located mainly under ocean islands not however under the central parts of major continents these results are obtained from comparing globally the observed travel time differences between ps conversions and ss precursors from the discontinuity at 410 km depth using published data and new observations from ocean island stations comparison of ss precursors and ps conversions however leads also to indications of significantly fewer narrow plumes in the upper mantle transition zone between 410 and 660 km depth than in the upper mantle above 410 km depth

the november 2009 paroxysmal explosions at stromboli two paroxysmal explosions occurred at stromboli volcano italy on 8 and 24 november 2009 analysis of recordings from video camera surveillance indicates that each paroxysm consisted of multiple bursts from different vents field surveys carried out within a few days after the two paroxysmal events allowed us to gather crucial data on eruptive deposits and document morphological variations occurring at the source vents integration of video analysis and field observations allowed making inferences on the eruptive dynamics of each explosive paroxysm the 24 november event in particular erupted a larger volume and coarser products dispersed further from the summit area resulting in a more hazardous event compared to the 8 november event that was largely confined to the upper part of the volcano