forecasting seismic scenarios on etna volcano italy through probabilistic intensity attenuation models a bayesian approach abstract in this paper we apply a probabilistic procedure to model the attenuation of the macroseismic intensity in the mt etna region which allows estimating probabilistic seismic scenarios starting from the local earthquake catalogue we select a dataset of 47 events having epicentral intensity i0 from vi to ix x ems and update the model parameters previously achieved for italy according to the bayesian paradigm for each class of epicentral intensity i0 we then estimate the probability distribution of the intensity at a site conditioned on the epicentre site distance through a binomial beta model under the assumption of a point seismic source and isotropic decay circular the mode of the distribution is taken as the expected intensity is at that site since the strongest earthquakes show a preferential propagation of shaking along the fault strike and a rapid decrease in the perpendicular direction we also consider the anisotropic decay elliptical of the intensity due to a linear source finite fault we therefore transform the plane so that the ellipse has the length of the fault rupture as maximum axis and its strike as azimuth is changed into a circle with fixed diameter then we apply the probabilistic model obtained for the isotropic case to the modified data the entire calculation procedure is implemented in the software proscen which given the location and the epicentral intensity and eventually the fault parameters of the earthquake to be simulated generates the probabilistic seismic scenario according to the isotropic and anisotropic models of attenuation the results can be plotted on grid maps representing 1 the intensity that can be exceeded with a fixed probability or 2 the probability of exceeding a fixed intensity value the first representation may also find application in seismic monitoring at etna volcano in order to produce real time intensity shakemaps based on the instrumental parameters calculated by the automatic earthquake processing system

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

compositions and taxonomy of 15 unusual carbonaceous chondrites abstract we used instrumental neutron activation analysis and petrography to determine bulk and phase compositions and textural characteristics of 15 carbonaceous chondrites of uncertain classification acfer 094 type 3 0 ungrouped cm related belgica 7904 mildly metamorphosed anomalous cm like chondrite possibly a member of a new grouplet that includes wisconsin range wis 91600 dhofar 225 and yamato 86720 dar al gani dag 055 and its paired specimen dag 056 anomalous reduced cv3 like dag 978 type 3 ungrouped dominion range 03238 anomalous magnetite rich co3 1 elephant moraine 90043 anomalous magnetite bearing co3 graves nunataks 98025 type 2 or type 3 ungrouped grosvenor mountains gro 95566 anomalous cm2 with a low degree of aqueous alteration hammadah al hamra hah 073 type 4 ungrouped possibly related to the coolidge loongana c l 001 grouplet lewis cliff lew 85311 anomalous cm2 with a low degree of aqueous alteration northwest africa 1152 anomalous cv3 pecora escarpment pca 91008 anomalous metamorphosed cm queen alexandra range 99038 type 2 ungrouped sahara 00182 type 3 ungrouped possibly related to hah 073 and or to c l 001 and wis 91600 mildly metamorphosed anomalous cm like chondrite possibly a member of a new grouplet that includes belgica 7904 dhofar 225 and y 86720 many of these meteorites show fractionated abundance patterns especially among the volatile elements impact volatilization and dehydration as well as elemental transport caused by terrestrial weathering are probably responsible for most of these compositional anomalies the metamorphosed cm chondrites comprise two distinct clusters on the basis of their 17o values approximately 4 for pca 91008 gro 95566 dag 978 and lew 85311 and approximately 0 for belgica 7904 and wis 91600 these six meteorites must have been derived from different asteroidal regions

lunar meteorites from oman abstract sixty named lunar meteorite stones representing about 24 falls have been found in oman in an area of 10 7 103 km2 in southern oman lunar meteorite areal densities average 1 g km 2 all lunar meteorites from oman are breccias although two are dominated by large igneous clasts a mare basalt and a crystalline impact melt breccia among the meteorites the range of compositions is large 9 32 al2o3 2 5 21 1 feo 0 3 38 g g 1 sm and 1 to 22 5 ng g 1 ir the proportion of nonmare lunar meteorites is higher among those from oman than those from antarctica or africa omani lunar meteorites extend the compositional range of lunar rocks as known from the apollo collection and from lunar meteorites from other continents some of the feldspathic meteorites are highly magnesian high mgo mgo feo compared with most similarly feldspathic apollo rocks two have greater concentrations of incompatible trace elements than all but a few apollo samples a few have moderately high abundances of siderophile elements from impacts of iron meteorites on the moon all lunar meteorites from oman are contaminated to various degrees with terrestrial na k p zn as se br sr sb ba u carbonates or sulfates the contamination is not so great however that it seriously compromises the scientific usefulness of the meteorites as samples from randomly distributed locations on the moon

linking so2 emission rates and seismicity by continuous wavelet transform implications for volcanic surveillance at san cristobal volcano nicaragua san cristobal volcano is the highest and one of the most active volcanoes in nicaragua its persistently high activity during the past decade is characterized by strong degassing and almost annual vei 1 2 explosions which present a threat to the local communities following an eruption on 8 september 2012 the intervals between eruptions decreased significantly which we interpret as the start of a new eruptive phase we present here the results of semi continuous so2 flux measurements covering a period of 18 months obtained by two scanning uv doas instruments installed as a part of the network for observation of volcanic and atmospheric change project and the results of real time seismic amplitude measurements rsam data our data comprise a series of small to moderately explosive events in december 2012 june 2013 and february 2014 which were accompanied by increased gas emissions and seismicity in order to approach an early warning strategy we present a statistical method for the joint analysis of gas flux and seismic data by using continuous wavelet transform and cross wavelet transform xwt methods this analysis shows that the xwt coefficients of so2 flux and rsam are in good agreement with the occurrence of eruptive events and thus may be used to indicate magma ascent into the volcano edifice such multi parameter surveillance efforts can be useful for the interpretation and surveillance of possible eruptive events and could thus be used by local institutions for the prediction of upcoming volcanic unrest

using lake sediment archives to improve understanding of flood magnitude and frequency recent extreme flooding in northwest uk we present the first quantitative reconstruction of palaeofloods using lake sediments for the uk and show that for a large catchment in nw england the cluster of devastating floods from 1990 to present is without precedent in this 558 year palaeo record our approach augments conventional flood magnitude and frequency fmf analyses with continuous lake sedimentary data to provide a longer term perspective on flood magnitude recurrence probabilities the 2009 flood the largest in 558 years had a recurrence interval larger 1 2 200 year than revealed by conventional flood estimation using shorter duration gauged single station records 1 1 700 year flood rich periods are non stationary in their correlation with climate indices but the 1990 2018 cluster is associated with warmer northern hemisphere temperatures and positive atlantic multidecadal oscillation monitored records rarely capture the largest floods and our palaeoflood series shows for this catchment such omissions undermine evaluations of future risk our approach provides an exemplar of how to derive centennial palaeoflood reconstructions from lakes coupled well with their catchments around the world

three dimensional spectral analysis of compositional heterogeneity at arruntia crater on 4 vesta using dawn fc abstract we introduce an innovative three dimensional spectral approach three band parameter space with polyhedrons that can be used for both qualitative and quantitative analyzes improving the characterization of surface compositional heterogeneity of 4 vesta it is an advanced and more robust methodology compared to the standard two dimensional spectral approach two band parameter space the dawn framing camera fc color data obtained during high altitude mapping orbit resolution 60 m pixel is used the main focus is on the howardite eucrite diogenite hed lithologies containing carbonaceous chondritic material olivine and impact melt the archived spectra of heds and their mixtures from relab hoserlab and usgs databases as well as our laboratory measured spectra are used for this study three dimensional convex polyhedrons are defined using computed band parameter values of laboratory spectra polyhedrons based on the parameters of band tilt r0 92 m r0 96 m mid ratio r0 75 m r0 83 m r0 83 m r0 92 m and reflectance at 0 55 m r0 55 m are chosen for the present analysis an algorithm in idl programming language is employed to assign fc data points to the respective polyhedrons the arruntia region in the northern hemisphere of vesta is selected for a case study because of its geological and mineralogical importance we observe that this region is eucrite dominated howarditic in composition the extent of olivine rich exposures within an area of 2 5 crater radii is 12 larger than the previous finding thangjam g et al 2014 meteorit planet sci 49 1831 1850 lithologies of nearly pure cm2 chondrite olivine glass and diogenite are not found in this region although there are no unambiguous spectral features of impact melt the investigation of morphological features using fc clear filter data from low altitude mapping orbit resolution 18 m pixel suggests potential impact melt features inside and outside of the crater our spectral approach can be extended to the entire vestan surface to study the heterogeneous surface composition and its geology

earthquake activity related to the 1991 eruption of the hekla volcano iceland the 1991 eruption of the hekla volcano started unexpectedly on 17 january no long term precursory seismicity was observed the first related activity was a swarm of small earthquakes that began approximately half an hour before the eruption intensive seismicity both earthquakes and volcanic tremor accompanied the violent onset of the eruption almost 400 events up to ml magnitude 2 5 were recorded during the first few hours during the later phases of the eruption the earthquake activity was modest and the main volcano related seismic signal was the persistent volcanic tremor the tremor died away together with the eruption on 11 march and hekla was seismically quiet until the beginning of june 1991 when a sudden swarm of numerous small shallow earthquakes occurred this activity is atypical for hekla and is interpreted to be a failed attempt to resume the eruption

interpretation of si concentrations in lake sediments three case studies the biogenic si concentration in a sediment can be determined as the non detrital si concentration by normalization of the total si concentration with al this procedure is based upon the assumptions that 1 that al exists predominantly in detrital i e minerogenic particles and 2 that biogenic si mainly diatom frustules is the dominating non detrital si phase this paper focuses on the reasons for the variations of the non detrital si concentration in these lake sediments data from three lakes are presented representing three principally different cases regarding the si concentration the processes controlling the concentrations of detrital and non detrital si are discussed

particle size fractionation of titanium and zirconium during weathering and pedogenesis of granitic rocks in nw spain abstract titanium and zr were analyzed in 10 weathering and pedogenetic soil profiles developed on granitic rocks from nw spain concentrations were obtained by xrf and the ti and zr bearing minerals were studied by petrographical sem and eds analysis both elements were measured in rock bulk soil and granulometric fractions sand 2000 50 m silt 50 2 m clay titanium concentrations in the rock varied between 0 5 and 4 2 g kg 1 and zr concentrations from 52 to 173 mg kg 1 concentrations in bulk soil for the different horizons remain almost unchanged and are strongly related to the element content of the parent rock in some epipedons ti content is relatively lower than that of the underlying horizons due to a dilution effect caused by the high organic matter content and the addition of fresh minerals from erosion upslope the mineralogical study revealed that zr is present exclusively in zircons while ti occurs in rutile ilmenite and titanite but mainly as a structural component of the biotite regarding the particle size fractions both elements behave differently zirconium is enriched in the silt fraction of all soil horizons with concentrations up to 5 times that of the parent rock while ti is enriched in the silt up to 5 times and clay fractions up to 12 times of the solum horizons and depleted in the sand fraction of the a horizons these results indicate that zr concentrations are mainly controlled by the abundance of zircons in the rock and their physical detachment from the host minerals upon weathering ti mainly depends on the release from the structure of biotites through chemical weathering and its reprecipitation as neoformed mineral phases this physicochemical fractionation of ti and zr in soils bears important implications for studies on soil genesis continuity of soil profiles and the calculation on enrichment factors which are based on the conservative behaviour of both elements

siderophile and other geochemical constraints on mixing relationships among hed meteoritic breccias we have used neutron activation and electron probe fused bead techniques to analyze the bulk major and trace element compositions of 104 named hed meteorites about 100 102 distinct meteorites depending upon pairings including 32 polymict eucrites 30 howardites and six diogenites most were not previously analyzed for siderophile trace elements many not even for major elements our typical sample was 350 mg and in some cases two separate chips were analyzed as a test of meteorite heterogeneity meteorites with extraordinary compositions include bluewing 001 an unequilibrated eucrite that is rich in ti sm and other incompatible elements y 791192 a cumulate dominated polymict eucrite and lew 87002 an oddly sm rich howardite dominated by a ferroan variety of diogenite the eucrite diogenite mixing ratio is the single most important factor determining the compositions of polymict heds but wide ranges in eucrite incompatible element contents in diogenite cr and v contents and in sc contents of both eucrites and diogenites make for diversity among the polymict heds as our new siderophile data help to show the common practice of describing the entire class of howardites as regolith breccias is erroneous most howardites are fragmental breccias showing no sign of origin from true in the lunar sense i e soil like near surface regolith howardites are highly diverse in ni content often remarkably ni poor compared to lunar regolith breccias however the few 8 howardites with between 300 and 1200 lg g ni consistently show some combination of other traits suggestive of regolith origin most importantly all four cases or five if we include malvern which appears to have been altered by annealing of howardites known to have enrichments in solar wind noble gases belong to the 300 lg g ni group in many cases an abundance of glasses particularly in spheroidal or turbid brown form provides additional evidence for regolith origin we propose that the important subset of howardites that are regolith breccias be formally distinguished by the designation regolithic howardite apart from high siderophile levels the regolithic howardites are compositionally distinctive in having al2o3 consistently near 8 9 wt corresponding to a eucrite diogenite mixing ratio of precisely 2 1 assuming the heds are reasonably representative of the ancient i e pre vestoid launch surface of vesta this clustering of regolith composition is difficult to explain unless most of the ancient diogenite component was brought to the surface in a single early episode i e probably a single great impact after which smaller scale cratering with no further major excavations of diogenite until the vestoid forming event efficiently homogenized the surface such a single excavation model may also help to explain why diogenites in marked contrast with eucrites are seldom polymict and why al2o3 poor diogenite dominated howardites consistently lack major siderophile enrichments the low siderophile contents of polymict eucrites are most enigmatic possibly in the hedasteroidal context low collision velocities etc only materials blended by multiple impacts consistently acquire major enrichments in siderophile elements 2009 elsevier ltd all rights reserved

long term observation of volcanic tremor on stromboli volcano italy a synopsis the features of seismic activity on stromboli are discussed and compared in terms of their relationship with the main changes of volcanic activity from 1990 to 1993

infrasound reveals transition to oscillatory discharge regime during lava fountaining implication for early warning 1 we present the analysis of 4 million infrasonic signals which include 39 episodes of lava fountains recorded at 5 5 km from the active vents we show that each eruptive episode is characterized by a distinctive trend in the amplitude waveform and frequency content of the acoustic signals reflecting different explosive levels lava fountain starts with an 93 min long violent phase of acoustic transients at 1 25 hz repeating every 2 5 s infrasound suddenly evolves into a persistent low frequency quasi monochromatic pressure oscillation at 0 4 hz we interpret this shift as induced by the transition from the slug discrete strombolian to churn flow sustained lava fountain regime that is reflecting an increase in the gas discharge rate we calculate that infrasonic transition can occur at a gas superficial velocity of 76 m s and it can be used to define infrasonic based thresholds for an efficient early warning system

seismo acoustic evidence for an avalanche driven phreatic eruption through a beheaded hydrothermal system an example from the 2012 tongariro eruption abstract the 6 august 2012 te maari eruption comprises a complex eruption sequence including multiple eruption pulses a debris avalanche that propagated 2 km from the vent and the formation of a 500 m long arcuate chasm located 300 m from the main eruption vent the eruption included 6 distinct impulses that were coherent across a local infrasound network marking the eruption onset at 11 52 18 all times utc an eruption energy release of 3 1012 j was calculated using a body wave equation for radiated seismic energy a similar calculation based on the infrasound record shows that 90 of the acoustic energy was released from three impulses at onset times 11 52 20 20 of total eruption energy 11 52 27 50 and 11 52 31 20 these energy impulses may coincide with eyewitness accounts describing an initial eastward directed blast followed by a westward directed blast and a final vertical blast pre eruption seismic activity includes numerous small unlocatable micro earthquakes that began at 11 46 50 two larger high frequency earthquakes were recorded at 11 49 06 and 11 49 21 followed directly by a third earthquake at 11 50 17 the first event was located within the scarp based on an arrival time location from good first p arrival times and probably represents the onset of the debris avalanche the third event was a tornillo characterised by a 0 8 hz single frequency resonance and has a resonator attenuation factor of q 40 consistent with a bubbly fluid filled resonator this contrasts with a similar tornillo event occurring 2 5 weeks earlier having q 250 1000 consistent with a dusty gas charged resonator we surmise from pre eruption seismicity and the observed attenuation change that the debris avalanche resulted from the influx of fluids into the hydrothermal system causing destabilisation and failure the beheaded hydrothermal system may have then caused depressurisation frothing of the remaining gas charged system leading to the onset of explosive activity

the frontier mountain meteorite trap antarctica the frontier mountain blue ice field is an important antarctic meteorite trap which has yielded 472 meteorite specimens since its discovery in 1984 remote sensing analyses and field campaigns from 1993 to 1999 have furnished new glaciological data on ice flow ice thickness bedrock topography ice ablation and surface mass transport by wind along with detailed descriptions of the field situation at the trap this solid set of data combined with an updated meteorite distribution map and terrestrial ages available from literature allows us to better describe the nature of the concentration mechanism in particular we observe that the meteorite trap forms in a blue ice field 1 located upstream of an absolute and a shallow sub ice barriers 2 characterized by compressive ice flow with horizontal velocities decreasing from 100 to 10 cm year on approaching the obstacle 3 undergoing mean ablation rates of 6 5 cm year 4 nourished by a limited snow accumulation zone extending 20 km upstream of the blue ice area we also draw the following conclusions 1 the origin of the meteorite trap can be explained according to the present day glaciological situation 2 the meteorite concentration develops according to the general principles of the ice flow model 3 the accumulation model can be described as stagnant ice or slow moving ice against an absolute and submerged barriers according to the descriptive schemes present in literature 4 the frontier mountain ice field is an effective trap for meteorites weighing more than 200 g for smaller masses the combination of wind and glacial drift may remove meteorites in less than a few tens of thousands of years 5 although the activation age of the frontier mountain trap is not yet constrained we infer that one of the most important findsites may be as old as 50 ka predating the last glacial maximum

the antarctic achondrite grove mountains 021663 an olivine rich winonaite abstract the grove mountains grv 021663 meteorite was collected from the grovemountains region of antarctica the meteorite is composed primarily of olivine fa 5 4 orthopyroxene fs 4 7 wo 3 0 chromian diopside en 53 6 fs 2 4 wo 44 troilite kamacite andplagioclase ab 74 5 or 4 an 21 5 minor phases include schreibersite and k feldspar themeteorite is highly weathered w3 and weakly shocked s2 we determine a whole rockoxygen isotopic composition of d 18 o 7 50 d 17 o 3 52 comparisons of these datawith other primitive achondrites have resulted in the reclassi cation of this meteorite as amember of the winonaite group the occurrences of troilite metal and schreibersite in grv021663 indicate that these minerals were once completely molten euhedral inclusions ofpyroxene within plagioclase further suggest that these may have crystallized from a silicatemelt while the depletion of plagioclase metal and troilite indicates that grv 021663 couldrepresent a residuum following partial melting on its parent asteroid trace elementdistributions in silicate minerals do not however con rm this scenario as with otherwinonaite meteorites the formation of grv 021663 probably relates to brecciation andmixing of heterogeneous lithologies followed by varying degrees of thermal metamorphismon the parent body asteroid peak metamorphic conditions may have resulted in localizedpartial melting of metal and silicate mineralogies but our data are not conclusive introductionthe primitive achondrite meteorites winonaites arecharacterized by having chondritic mineralogies andchemical compositions but achondritic recrystallized textures for the most part they are ne to mediumgrained equigranular rocks some samples however contain what appear to be relic chondrules e g pontlyfni mt morris wisconsin and northwest africa nwa 1463 benedix et al 1998 2003 their oxidationstates are intermediate between those of enstatite and hchondrites and feni fes veins that constitute the rstpartial melts of a chondritic precursor material arecommon see figs 1a and 2a meteorites of this groupare primarily composed of orthopyroxene olivine diopside plagioclase troilite fe ni alloy and minoramounts of chromite and phosphate in addition theymay contain characteristic accessory minerals such asalabandite daubree lite schreibersite benedix et al 1998 amphibole is reported in at least one sample hammadah al hamra hah 193 floss et al 2007 there are several attributes that collectivelydistinguish the winonaites from other achondritemeteorite groups such as 1 highly reduced mineralassemblage s 2 distinct oxygen isotopic compositions 3 the abundance and distribution of metal s andtroilite and 4 characteristic accessory mineralogies benedix et al 1998 winonaites may derive from a1329

the transition from summit to flank activity at mt etna sicily italy inferences from the petrology of products erupted in 2007 2009 abstract mt etna is an active basaltic volcano where both flank and summit eruptions take place in recent decades the south east summit crater sec has in particular been characterized by episodic eruptions consisting of recurrent lava fountains associated with lava flow emissions and lasting from a few weeks to months recent volcanic activity shows that if there is a transition from an episodic summit eruption to a flank eruption then this usually takes place while the last paroxysm of the episodic eruption is still underway by contrast the 2007 08 episodic eruption at sec was followed by the 2008 09 flank activity which started three days after the conclusion of the last paroxysm coinciding with the strong earthquake m 7 9 in sichuan china whose perturbations were recorded by the monitoring network of mt etna we therefore investigated the transition from a summit episodic eruption at sec to flank activity utilizing a petrologic study of the products erupted from 2007 to 2009 integrated with literature data the compositional variability of the products may largely be explained by a mixing between an evolved magma stored in the sec reservoir and a more primitive magma which intrudes it in the studied period the most significant episodes of magma recharge occurred before the onset of the 2007 08 episodic eruption and during the 2008 09 flank activity more precisely before june 2008 according to previous studies the seven paroxysms of the 2007 08 episodic eruption at sec have been interpreted as resulting from the disruption of a foam layer at the top of the sec reservoir which was rebuilt before each subsequent episode the transition from the 2007 08 episodic eruption at sec to the 2008 09 flank activity was essentially triggered by the sichuan earthquake which caused a variation of dynamic stress it caused the volatile exolution the pressurization of sec stored magma and the consequent fracturing of the surrounding rocks where magma intruded to then be erupted during the 2008 09 flank activity

beni m hira a new chondritic l6 meteorite fall from tunisia the beni m hira meteorite fell on january 8 2001 in southeastern tunisia this is only the fifth observed fall from tunisia on the basis of mineralogical petrographic and geochemical data the stone can be classified as an l6 chondrite of shock stage s5

processes of flood triggered detrital layer deposition in the varved lake mondsee sediment record revealed by a dual calibration approach a succession of 23 sub millimetre to maximum 12 mm thick mostly flood triggered detrital layers deposited between 1976 and 2005 was analysed in 12 varved surface sediment cores from meso scale peri alpine lake mondsee applying microfacies and high resolution micro x ray fluorescence analyses detailed intrabasin comparison of these layers enabled identification of i different source areas of detrital sediments ii flood triggered sediment flux and local erosion events and iii seasonal differences of suspended flood sediment distribution within the lake basin additional calibration of the detrital layer record with river discharge and precipitation data reveals different empirical thresholds for flood layer deposition for different parts of the basin at proximal locations detrital layer deposition requires floods exceeding a daily discharge of 40 m3 s 1 whereas at a location 2 km more distal an hourly discharge of 80 m3 s 1 and at least 2 days of discharge above 40 m3 s 1 are necessary furthermore we observe a better correlation between layer thickness and flood amplitude in the depocentre than in distal and proximal areas of the basin although our results are partly site specific the applied dual calibration approach is suitable to precisely decipher flood layer formation processes and thereby improve the interpretation of long flood time series from lake sediments

multiple coincident eruptive seismic tremor sources during the 2014 2015 eruption at holuhraun iceland we analyze eruptive tremor during one of the largest effusive eruptions in historical times in iceland 2014 15 holuhraun eruption seismic array recordings are compared with effusion rates deduced from moderate resolution imaging spectroradiometer modis recordings and ground video monitoring data and lead to the identification of three coexisting eruptive tremor sources this contrasts other tremor studies that generally link eruptive tremor to only one source usually associated with the vent the three sources are i a source that is stable in back azimuth and shows bursts with ramp like decrease in amplitude at the beginning of the eruption we link it to a process below the open vents where the bursts correlate with the opening of new vents and temporary increases in the lava fountaining height ii a source moving by a few degrees per month while the tremor amplitude suddenly increases and decreases back azimuth and slowness correlate with the growing margins of the lava flow field whilst contact with a river led to fast increases of the tremor amplitude iii a source moving by up to 25 southwards in 4 days that cannot be related to any observed surface activity and might be linked to intrusions we therefore suggest that eruptive tremor amplitudes energies are used with caution when estimating eruptive volumes effusion rates or the eruption explosivity as multiple sources can coexist during the eruption phase our results suggest that arrays can monitor both the growth of a lava flow field and the activity in the vents

failed eruptions revealed by pattern classification analysis of gas emission and volcanic tremor data at mt etna italy during the spring of 2007 paroxysmal activity occurred at the southeast crater of mt etna always associated with sharp rises in the amplitude of the volcanic tremor activity ranged from strong strombolian explosions to lava fountains coupled with copious emission of lava flows and tephra during inter eruptive periods recurrent seismic unrest episodes were observed in the form of temporary enhancements of the volcanic tremor amplitude but they did not culminate in eruptive activity here we present the results of an analysis of these inter eruptive periods by integrating seismic volcanic tremor in soil radon plume so2 flux and thermal data so2 flux and thermal radiation are envisaged as the smoking gun and certifying that changes in seismic or radon data can be considered as volcanogenic short term changes were investigated by pattern classification based on kohonen maps and fuzzy clustering on volcanic tremor radon and ambient parameters pressure and temperature our results unveil failed eruptions between february and april 2007 that are explained as ascending magma batches which triggered repeated episodes of gas pulses and rock fracturing but that failed to reach the surface

continuous soil radon monitoring during the july 2006 etna eruption 1 continuous soil radon monitoring was carried out near the southeast crater sec of mt etna during the 10 day july 2006 strombolian effusive eruption this signal was compared with simultaneously acquired volcanic tremor and thermal radiance data the onset of explosive activity and a lava fountaining episode were preceded by some hours with increases in radon soil emission by 4 5 orders of magnitude which we interpret as precursors minor changes in eruptive behavior did not produce significant variations in the monitored parameters the remarkably high radon concentrations we observed are unprecedented in the literature we interpret peaks in radon activity as due primarily to microfracturing of uranium bearing rock these observations suggest that radon measurements in the summit area of etna are strongly controlled by the state of stress within the volcano and demonstrate the usefulness of radon data acquisition before and during eruptions citation neri m b behncke m burton g galli s giammanco e pecora e privitera and d reitano 2006 continuous soil radon monitoring during the july 2006 etna eruption geophys res lett 33 l24316 doi 10 1029 2006gl028394

analysis of phreatic events at ruapehu volcano new zealand using a new som approach abstract we apply self organising maps som to assess the low level seismic activity prior to small scale phreatic events at ruapehu volcano new zealand the som approach allows an automatic pattern recognition virtually independent from a priori knowledge volcanic tremor spectra are randomly presented to the network in a competitive iterative training process followed by a hierarchical clusterization of the som nodes spectra are then projected ordered by time to clusters on the map a coherent time evolution of the data through the clusters can highlight the existence of different regimes and the transitions between them two ruapehu events were examined a phreatic event on 4 october 2006 which displaced the crater lake producing a 4 m high wave on the lake edge and the more energetic 25 september 2007 phreatic eruption the som analysis provides a classification of tremor spectral patterns that clusters into three regimes that we label by colours the pattern for both eruptions is consistent with a pre eruption spectral pattern including enhanced spectral energy in the range of 4 to 6 hz labelled green tremor this gives way to spectra having broader energy between 2 and 6 hz the so called red tremor just prior to the eruption the post eruption pattern includes spectral peaks at generally lower frequencies of 2 to 4 hz the so called blue tremor clusterization into only three groups yields highly non unique solutions which cannot explain the variety of processes operating at ruapehu over long time periods regardless the approach highlights noteworthy similarities that may be explained by a pattern of slow pressurisation under a hydrothermal or magmatic seal green followed by seal failure red and subsequent de pressurisation blue for the two events studied although the application shown here is limited we think it demonstrates the power of this classification approach

seasonal controls on sediment transport and deposition in lake ohau south island new zealand implications for a high resolution holocene palaeoclimate reconstruction laminated sediments in lake ohau mackenzie basin new zealand offer a potential high resolution climate record for the past 17 kyr such records are particularly important due to the relative paucity of detailed palaeoclimate data from the southern hemisphere mid latitudes this paper presents outcomes of a study of the sedimentation processes of this temperate lake setting hydrometeorological limnological and sedimentological data were collected over a 14 month period between 2011 and 2013 these data indicate that seasonality in the hydrometeorological system in combination with internal lake dynamics drives a distinct seasonal pattern of sediment dispersal and deposition on a basin wide scale sedimentary layers that accumulate proximal to the lake inflow at the northern end of the lake form in response to discrete inflow events throughout the year and display an event stratigraphy in contrast seasonal change in the lake system controls accumulation of light winter and dark summer laminations at the distal end of the lake resulting in the preservation of varves this study documents the key processes influencing sediment deposition throughout lake ohau and provides fundamental data for generating a high resolution palaeoclimate record from this temperate lake

shock metamorphism of ordinary chondrites a revised petrographic classification of progressive stages of shock metamorphism of ordinary chondrites is proposed six stages of shock s1 to s6 are defined based on shock effects in olivine and plagioclase as recognized by thin section microscopy the characteristic shock effects of each shock stage are s1 unshocked sharp optical extinction of olivine s2 very weakly shocked undulatory extinction of olivine s3 weakly shocked planar fractures in olivine s4 moderately shocked mosaicism in olivine s5 strongly shocked isotropization of plagioclase maskelynite and planar deformation features in olivine and s6 very strongly shocked recrystallization of olivine sometimes combined with phase transformations ringwoodite and or phases produced by dissociation reactions s6 effects are always restricted to regions adjacent to melted portions of a sample which is otherwise only strongly shocked in stages s3 to s6 localized melting results from stress and temperature peaks which locally deviate from the equilibration shock pressure due to differences in shock impedance these melting effects are a opaque melt veins shock veins b melt pockets with interconnecting melt veins c melt dikes and d troilite metal deposits in fractures based on a critical evaluation of data from shock recovery experiments a shock pressure calibration for the six shock stages is proposed which defines the s1 s2 s2 s3 s3 s4 s4 s5 and s5 s6 transitions at 5 5 10 15 20 30 35 and 45 55 gpa respectively whole rock melting and formation of impact melt rocks or melt breccias occurs at about 75 90 gpa the symbol for the shock stage may be used in combination with the symbol for the petrologic type to abbreviate the complete classification of a chondrite e g h5 s3 we propose this new shock classification and pressure calibration system to replace previous systems which are out of date with respect to the pressure calibration nominally restricted to l chondrites and based on incomplete and in part illdefined sets of shock effects we have classified seventy six ordinary chondrites using the new classification system and conclude the following 1 1 shock effects and the sequence of progressively increasing degrees of shock metamorphism are very similar in h l and ll groups differences in the frequency distribution of shock stages are relatively minor e g l chondrites appear to have the largest fraction with stages s5 and s6 this suggests that the collisional histories of the h l and ll parent bodies were similar 2 2 petrologic type 3 chondrites are deficient in stages s4 to s6 and with increasing petrologic type the frequency of stages s4 to s6 increases we suggest that the more porous and volatile rich type 3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type volatiles trapped in pores cause shock induced dispersal of the shocked and melted material into small particles which are not expected to survive as meteorites 3 3 stage s3 is the most abundant in nearly all petrologic types 4 4 at shock pressures in excess of about 35 gpa s5 and s6 4he and 40ar are almost completely lost pressures below 10 gpa s1 and s2 do not cause noble gas losses

shock features in iron nickel metal and troilite of l group ordinary chondrites shock metamorphic features in opaque minerals feni metal and troilite of 22 l chondrites have been studied petrographically and geochemically in an attempt to establish a connection between the present silicate based shock classification scheme stoffler et al 1991 and the peak shock and postshock thermal history recorded in these minerals unshocked to weakly shocked s1 s3 l chondrites contain feni metal and troilite that display textures related to normal slow cooling they may also contain rare disequilibrium shock features which suggest localized departures from equilibrium shock conditions above shock stage s3 selected melting of feni metal and troilite produces melt droplets whose composition and abundance correspond to the maximum equilibrium shock state achieved by the sample at these higher shock levels the abundance of other shock induced features such as polycrystalline kamacite sheared and fizzed troilite coarse grained pearlitic plessite polycrystalline troilite and polymineralic melt veins serve as textural criteria that can be used to establish peak shock conditions minimum postshock temperatures obtained from analyses of plessite components show a systematic increase in temperature with an increase in shock stage thereby providing additional information about the postshock thermal histories of l chondrites at the highest shock levels recorded in l chondrites s6 and above melting and chemical homogenization of feni metal produces flattened ni profiles that may partially to completely obscure any evidence for an earlier slow cooling history all of these features serve as aids for shock classifying l chondrites as well as for quantifying minimum peak temperatures that resulted during shock metamorphism

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

the meteorite collection at museo di storia naturale pisa university italy the historical meteorite collection of museo di storia naturale pisa university is presented in this catalog dating back to at least 1860 the collection currently as of june 2003 contains 30 specimens of 26 individual meteorites representing about 50 kg of extraterrestrial material the collection includes 2 carbonaceous chondrites 12 ordinary chondrites 1 achondrite 4 stony iron meteorites and 7 iron meteorites including three remarkable specimens the main mass of bagnone 48 kg the fourth largest mass of quenggouk 717 5 g and a large nearly complete individual of the siena showerfall 318 8 g

hydrological thresholds and basin control over paleoflood records in lakes the scarcity of long term hydrological data is a barrier to reliably determining the likelihood of floods becoming more frequent and or intense in a warmer world lake sediments preserve characteristic event layers offering the potential to develop widely distributed and unique chronologies of historical floods inferring flood magnitude remains a greater challenge previously overcome in part by analyzing sharply laminated polar or alpine sequences here we demonstrate an approach to obtain flood frequency and magnitude data from an unexploited resource the largely visually homogeneous organic sediments that typify most temperate lakes the geochemical composition and end member modeling of sediment trap and adjacent short core particle size data for brotherswater northwest england discriminates the signature of infrequent coarse grained flood deposits from seasonal and longer term allogenic enhanced discharge and sediment supply during winter and autogenic summer productivity thermal mixing depositional processes comparing the paleoflood reconstruction to local river discharges shows that hydrological thresholds censor event signature preservation with 4 yr recurrence intervals detectable in delta proximal sediments declining to 9 yr in the lake center event threshold discharge and process characterization are essential precursors to discerning flood magnitude from sediment archives implementation of our approach in globally prevalent temperate lakes offers a vast unique repository of long term hydrological data for hydrologists climate modelers engineers and policy makers addressing future flood risks

seismic activity related to the 2000 eruption of the hekla volcano iceland the 2000 hekla eruption took place from february 26 to march 8 its seismic expressions were a swarm of numerous small earthquakes related to its onset and low frequency volcanic tremor that continued throughout the eruption a swarm of small earthquakes was observed some 80 min before the onset of the eruption and the size of the events increased with time low frequency volcanic tremor with a characteristic frequency band of 0 5 1 5 hz and dominant spectral peak s at 0 7 0 9 hz became visible at 18 19 gmt on february 26 marking the onset of the eruption the tremor amplitude rose quickly and was very high in the beginning of the eruption however it soon began to decrease after about an hour in general the seismic activity related to the 2000 hekla eruption was very similar to what was observed in the previous eruption in 1991 based on knowledge gained from seismicity and strain observations from 1991 this was the first time that a hekla eruption was predicted

contrasting triggering mechanisms of the 2001 and 2002 2003 eruptions of mount etna italy abstract mount etna produced two significant eruptions in 2001 and 2002 2003 which we have analysed using geological seismic and deformation data these eruptions showed some similarities such as the activating of two magmatic plumbing systems central lateral and eccentric but they differed in their triggering mechanisms while the 2001 eruption was largely the result of the emplacement of a n s eccentric dike independent from the central conduits consistent with e w regional extension the 2002 2003 eruption occurred in response to a major flank slip on the eastern and southeastern sides of the volcano this is demonstrated by the spatial and temporal distribution of seismicity and deformation preceding and accompanying the two eruptions during the months prior to the 2001 eruption most epicenters were concentrated on the southern flank at depths of 5 15 km below sea level during the 4 days before the eruption earthquake hypocenters migrated to shallower levels from 5 km bsl upward indicating the emplacement of the eccentric dike this is confirmed by the patterns of ground fracturing observed in the field and deformation documented by electronic distance measurements edm in contrast the months before the 2002 2003 eruption were characterised by shallower seismicity mainly concentrated along the active faults bordering the slipping flank sector flank slip accelerated in september 2002 and a second more vigorous acceleration of flank slip occurred on 26 27 october 2002 accompanying the opening of eruptive vents the very short 2 h seismic crisis preceding the onset of eruptive activity stands in neat contrast with the 4 days of intense seismicity before the 2001 eruption subsequently flank slip deformation extended all over the eastern and southeastern flanks of the volcano causing serious damage in this sector the events of 2001 2003 can be seen as a continuous chain of intimately interacting processes including regional tectonics magma accumulation and eruption and flank instability in this scenario the 2001 eruption led to increased flank instability that subsequently accelerated and culminated with the massive flank slip which in turn facilitated the 2002 2003 eruption this sequence of events points to a long term feedback mechanism between magmatism and flank instability at etna

accessory silicate mineral assemblages in the bilanga diogenite a petrographic study the petrographic relationships in diogenites between orthopyroxene and minor phases such as chromite troilite diopside plagioclase and silica are often obscured by the intense brecciation that characterizes these meteorites although brecciated bilanga preserves numerous clasts displaying primary textural relations between orthopyroxene and these minor phases that are large enough to analyze by electron microprobe in this study we focus on the distribution composition and origin of the minor phases in bilanga to provide new insights into the crystallization and metamorphic history of these rocks the samples examined consist mainly of orthopyroxene grains plus five types of assemblages containing diopside a fe rich phase chromite troilite and or fe ni metal plagioclase silica we interpret type 1 assemblages as being remnants of intercumulus melt trapped in the interstices between orthopyroxene grains after crystal settling in a magma chamber type 2 assemblages appear to have formed by heterogeneous exsolution during thermal metamorphism type 3 assemblages are believed to be remnants of other assemblages that have been shocked melted and rapidly recrystallized by impact events type 4 assemblages consist of veins that also appear to have formed from trapped intercumulus melt regions of silica rich mesostasis type 5 appear to be larger patches of more evolved intercumulus melt that have been significantly affected by late stage impact melting finally large clasts containing plagioclase diopside are interpreted to be exotic fragments of a different but possibly related rock type incorporated in the bilanga breccia

stable oxygen and carbon isotopes of carbonates in lake sediments as a paleoflood proxy lake sediments are increasingly explored as reliable paleoflood archives in addition to established flood proxies including detrital layer thickness chemical composition and grain size we explore stable oxygen and carbon isotope data as paleoflood proxies for lakes in catchments with carbonate bedrock geology in a case study from lake mondsee austria we integrate high resolution sediment trapping at a proximal and a distal location and stable isotope analyses of varved lake sediments to investigate flood triggered detrital sediment flux first we demonstrate a relation between runoff detrital sediment flux and isotope values in the sediment trap record covering the period 2011 2013 ce including 22 events with daily hourly peak runoff ranging from 10 24 m3 s 1 to 79 110 m3 s 1 the three to ten fold lower flood triggered detrital sediment deposition in the distal trap is well reflected by attenuated peaks in the stable isotope values of trapped sediments next we show that all nine flood triggered detrital layers deposited in a sediment record from 1988 to 2013 have elevated isotope values compared with endogenic calcite in addition even two runoff events that did not cause the deposition of visible detrital layers are distinguished by higher isotope values empirical thresholds in the isotope data allow estimation of magnitudes of the majority of floods although in some cases flood magnitudes are overestimated because local effects can result in too high isotope values hence we present a proof of concept for stable isotopes as reliable tool for reconstructing flood frequency and although with some limitations even for flood magnitudes less

hazards from pyroclastic density currents at mt etna italy abstract despite the recent recognition of mount etna as a periodically violently explosive volcano the hazards from various types of pyroclastic density currents pdcs have until now received virtually no attention at this volcano large scale pyroclastic flows last occurred during the caldera forming ellittico eruptions 15 16 ka ago and the risk of them occurring in the near future is negligible however minor pdcs can affect much of the summit area and portions of the upper flanks of the volcano during the past 20 years small pyroclastic flows or base surge like vapor and ash clouds have occurred in at least 8 cases during summit eruptions of etna four different mechanisms of pdc generation have been identified during these events 1 collapse of pyroclastic fountains as in 2000 and possibly in 1986 2 phreatomagmatic explosions resulting from mixing of lava with wet rock 2006 3 phreatomagmatic explosions resulting from mixing of lava with thick snow 2007 4 disintegration of the unstable flanks of a lava dome like structure growing over the rim of one of the summit craters 1999 all of these recent pdcs were of a rather minor extent maximum runout lengths were about 1 5 km in november 2006 and march 2007 and thus they represented no threat for populated areas and human property around the volcano yet events of this type pose a significant threat to the lives of people visiting the summit area of etna and areas in a radius of 2 km from the summit craters should be off limits anytime an event capable of producing similar pdcs occurs the most likely source of further pdcs in the near future is the southeast crater the youngest most active and most unstable of the four summit craters of etna where 6 of the 8 documented recent pdcs originated it is likely that similar hazards exist in a number of volcanic settings elsewhere especially at snow or glacier covered volcanoes and on volcano slopes strongly affected by hydrothermal alteration

39ar 40ar ages and origin of excess 40ar in martian shergottites we report new 39ar 40ar measurements on 15 plagioclase pyroxene and or whole rock samples of 8 martian shergottites all age spectra suggest ages older than the meteorite formation ages as defined by sm nd and rb sr isochrons employing isochron plots only los angeles plagioclase and possibly northwest africa nwa 3171 plagioclase give ages in agreement with their formation ages isochrons for all shergottite samples reveal the presence of trapped martian 40ar 40arxs which exists in variable amounts in different lattice locations some 40arxs is uniformly distributed throughout the lattice resulting in a positive isochron intercept and other 40arxs occurs in association with k bearing minerals and increases the isochron slope these samples demonstrate situations where linear ar isochrons give false ages that are too old after subtracting 40ar that would accumulate by 40k decay since meteorite formation and small amounts of terrestrial 40ar all young age samples give similar 40arxs concentrations of 1 2 x 10 6 cm 3 g but a variation in k content by a factor of 80 previously reported nasa johnson space center data for zagami shergotty yamato y 000097 y 793605 and queen alexandra range que 94201 shergottites show similar concentrations of 40arxs to the new meteorite data reported here similar 40arxs in different minerals and meteorites cannot be explained as arising from martian atmosphere carried in strongly shocked phases such as melt veins we invoke the explanation given by bogard and park 2008 for zagami that this 40arxs in shergottites was acquired from the magma similarity in 40arxs among shergottites may reveal common magma sources and or similar magma generation and emplacement processes

annually resolved lake record of extreme hydro meteorological events since ad 1347 in ne iberian peninsula abstract we present an annual reconstruction of extreme rainfall events interpreted from detrital layers and turbidites interbedded within a varved sediment record since the 14 th century in montcortes lake ne spain 1027 m a s l clastic microfacies intercalated within the biochemical calcite varves were characterized and their depositional dynamics interpreted using high resolution geochemical and sedimentological analyses annual number of detrital layers was compared against instrumental records of extreme daily rainfalls providing minimum rainfall thresholds and return periods associated to the identified types of clastic microfacies non continuous detrital layers were deposited during rainfall events higher than 80 mm 2 year return period while graded detrital layers and turbidites were associated with higher magnitude rainfall events 90 mm and 4 year return period the frequency distribution of extreme hydro meteorological events is not stationary and its pattern coincides with historical floods from the nearby segre river high frequency of heavy rainfalls occurred during the periods ad 1347 1400 and ad 1844 1894 a lower frequency of heavy rainfall was found during the periods ad 1441 1508 1547 1592 1656 1712 1765 1822 and 1917 2012 the 20 th century stands out as the longest interval within the studied period of very low number of extreme rainfall events variability in extreme rainfall events prior to the 20 th century is in phase with solar activity suggesting a mechanistic link in mid latitude atmospheric circulation patterns that ceased during the 20 th century

shock metamorphism of enstatite chondrites abstract we have extended the shock metamorphism classification scheme of stoffler et al 1991 to account for shock effects in orthopyroxene and applied it to sixty enstatite chondrites orthopyroxene exhibits the following sequence of progressive shock effects shock stage s1 unshocked sharp optical extinction s2 very weakly shocked undulose extinction s3 weakly shocked development of clinoenstatite lamellae parallel to 100 s4 moderately shocked weak mosaicism s5 strongly shocked strong mosaicism as in the stoffler et al 1991 scheme stage s5 is characterized principally by the solid state transformation of crystalline plagioclase into maskelynite most el3 chondrites exhibit foliations caused by impact deformation of chondrules and metal particles el5 and el6 chondrites are all shock stage s2 because opaque veins are rare in s2 ordinary chondrites it is plausible that the centimeter size kamacite veins in atlanta and blithfield and the 1 6 cm long oldhamite rich vein in jajh deh kot lalu all el6 formed when their hosts were shocked to s3 s5 levels because removal of shock stage s3 s5 features including repair of shock damaged orthopyroxene requires levels of metamorphism comparable to those experienced by petrologic type 5 to 6 chondrites we infer that proto el6 material was shocked to s3 s5 levels prior to peak metamorphism and shocked again to stage s2 after metamorphism overall enstatite chondrites appear to have suffered greater shock damage than ordinary and carbonaceous chondrites

itqiy a metal rich enstatite meteorite with achondritic texture itqiy is a unique coarse grained metal rich enstatite meteorite that was found in the western sahara and consists of two rocks together weighing 4 72 kg which are both completely coated with fusion crust we report results from our electron microprobe and instrumental neutron activation analysis techniques itqiy consists of subhedral equigranular millimeter sized enstatite 25 vol of millimeter sized kamacite and a few tiny intergrowths of sulfides and kamacite relic chondrules are absent pyroxene fs0 2 is chemically similar to enstatite in el chondrites but the metal is closer in composition to that in eh chondrites sulfides resemble those in e chondrites but their compositions are distinct from those in both el and eh chondrites itqiy clearly formed under very reducing conditions but it does not appear to have formed from eh or el chondrites two thermal events can be distinguished silicate compositions including rare earth element abundances indicate loss of partial melt and slow cooling heterogeneous sulfides indicate a subsequent reheating and quenching event which may have been due to shock as many enstatite grains show shock stage s3 features

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

the classification of seismo volcanic signals using hidden markov models as applied to the stromboli and etna volcanoes the aim of this work is to apply the hidden markov model hmm method to recognise seismic signals belonging to different active volcanoes we use data obtained from two field surveys carried out in 1997 and 1999 at stromboli and etna respectively for stromboli we used two types of seismic signals for recognition purposes strombolian explosions and background seismic noise whilst for etna we used volcanic tremors and tremor bursts we initially proceeded to visually identify the signals and to segment the data to obtain a model for each event class we then applied these models separately to each volcano dataset finally combining both datasets as a test of the portability of the system the method analyses the seismograms and compares the characteristics of the data to a number of pre defined event classes if a signal is present the method detects its occurrence and produces a classification we observed that to obtain reliable results a careful and adequate segmentation process is crucial and that each signal type must be represented by its own specific model once we had built this model the success level of the system was high the success rates obtained indicated that the method was fully able to detect isolate and identify signals from raw seismic data these results imply that once an adequate training process has been used this method is particularly appropriate for work in real time as well as concurrently with the data acquisition system

the zaklodzie enstatite meteorite mineralogy petrology origin and classification the zaklodzie meteorite was found in september 1998 about 40 km west of zamo c in southeast poland macroscopic and microscopic observations in transmitted and reflected light microprobe analyses cathodoluminescence images and x ray diffraction data show that the meteorite is composed of clino and orthoenstatite two generations of feldspars relict olivine forsterite a polymorph of sio2 apparently cristobalite and opaque minerals fe ni alloy kamacite and taenite troilite schreibersite graphite and sulfide mg mn fe s which is probably keilite the texture is fine to inequigranular of cumulate type locally intergranular the mgs fes thermometer indicates that the sulfides crystallized at 580 600 oc thus the zaklodzie meteorite formed by the nearly complete melting of an enstatite chondrite protolith probably at 4 4 ga the process was likely caused by the decay of the 26al nuclide in the planetesimal interior the second stage of its evolution which could have happened at 2 1 ga involved partial re melting of most fusible components probably due to collision with another body the structure composition and origin of the meteorite and its relation to the parent rock indicate that zaklodzie may represent a primitive enstatite achondrite

sediment source and hydroclimatic inferences from glacial lake sediments the postglacial sedimentary record of lillooet lake british columbia lillooet river drains 3850 km2 of partly glacier covered terrain before entering lillooet lake in the southern coast mountains of british columbia the elongated lake covers an area of 21 km2 and forms a deep basin with water depths to 137 m acoustic profiling of the subbottom and sampling of the surface sediments reveals that total sediment thickness varies from 30 m in the north half of the lake near lillooet delta and then declines to less than 16 m in the south up valley ice retreat approximately 11 000 years bp resulted in conformable sediments in the main lake indicative of turbidity currents off lillooet delta which infilled and flattened the underlying surface a sill which separates the main and south basins prevents the down lake progression of turbidity currents resulting in conformable deposits indicative of rain out i e settling processes only a major acoustic reflector at about 6 9 m below the modern sediment surface is associated with a well dated volcanic eruption and sediment yield event in the upper basin at 2400 years bp modern glaciolacustrine deposition forms varves which accumulate at a rate of up to 28 mm year 1 in the north and decline to less than 0 9 mm year 1 in the south the occurrence of two sediment runoff regimes one average and the other extreme leads to distinct differences in varve sedimentology and varve thickness de coupling the two signals using sedimentary evidence alone cannot be done consistently so a sediment yield runoff relation for the lake r2 41 contains considerable noise an annual sediment accumulation chronology covering the last 125 years shows a much higher frequency of extreme runoff sediment yield events during the post 1940 interval this parallels a documented change in climate of the region after 1945 and suggests that a longer varve chronology would provide a good high resolution proxy record of hydroclimatic variations

the origin of alteration orangettes in dhofar 019 implications for the age and aqueous history of the shergottites the shergottites are the largest group of martian meteorites and the only group that has not been found to contain definitive evidence of martian aqueous alteration given recent reports of current liquid water at the surface of mars this study aimed to investigate in detail the possibility of martian phyllosilicate within shergottite dhofar 019 optical and scanning electron microscopy followed by transmission electron microscopy confirmed the presence of alteration orangettes with a layered structure consisting of poorly ordered mg phyllosilicate and calcite these investigations identified maskelynite dissolution followed by mg phyllosilicate and calcite deposition within the dissolution pits as the method of orangette production the presence of celestine within the orangette layers the absence of shock dislocation features within calcite and the mg rich nature of the phyllosilicate all indicate a terrestrial origin for these features on dhofar 019

geochronology and physical context of oldowan site formation at kanjera south kenya oldowan sites in primary geologic context are rare in the archaeological record here we describe the depositional environment of oldowan occurrences at kanjera south kenya based on field descriptions and granulometric analysis excavations there have recovered a large oldowan artefact sample as well as the oldest substantial sample of archaeological fauna the deposits at kanjera south consist of 30 m of fluvial colluvial and lacustrine sediments magneto and bio stratigraphy indicate the kanjera south member of the kanjera formation was deposited between 2 3 and 1 92 million years ago ma with 2 0 ma being a likely age for the archaeological occurrences oldowan artefacts and associated fauna were deposited in the colluvial and alluvial silts and sands of beds ks 1 to ks 3 in the margins of a lake basin field descriptions and granulometric analysis of the sediment fine fraction indicates sediments from within the main archaeological horizon were emplaced as a combination of tractional and hyperconcentrated flows with limited evidence of debris flow deposition this style of deposition is unlikely to significantly erode or disturb the underlying surface and therefore promotes preservation of surface archaeological accumulations hominins were repeatedly attracted to the site locale and rapid sedimentation minimal bone weathering and an absence of bone or artefact rounding further indicate that fossils and artefacts were quickly buried

aspects of the validation of magnetic remanence in meteorites meteorite magnetic records constitute physical evidence of processes acting during early solar system evolution consequently the validation of these records is important in meteorite research the first step in the validation process should be the rem value the rem value is the ratio of natural remanence nrm to saturation remanent magnetization imparted by a 1 t magnetic field sirm the rem values range over 3 to 4 orders of magnitude for stony meteorites and for chondrules from allende c3v s1 bjurbole l4 s1 and chainpur ll3 s1 meteorites the rem values computed from published nrm and sirm data identify many orders of magnitude range in the rem values including rem values 100 10 3 these data suggest a dependence for the nrm intensity on the curatorial location from which the sample was obtained any earth rock acquiring thermoremanent magnetization trm in the geomagnetic field has a restricted range in rem mostly between 5 and 50 10 3 the exception being the mineral hematite in the multidomain size range the only terrestrial samples with rem much greater than 100 10 3 are those struck by lightning the rem value provides a physical basis for recognition between valid records and those that might be contaminated the isothermal remanence acquisition ra curve is presented as a contamination curve that allows an indication of the level of magnetic field contamination required to give the computed rem rm sirm value in the case of the bjurbole and chainpur chondrules with rem values 100 10 3 the ra curve indicates that unrealistically large contamination magnetic fields would be required to give rem values greater than 100 10 3 this would suggest contamination other than by a hand magnet that is normally available to an experimenter this would require an explanation that would involve large magnetic fields during chondrule formation or some extraordinary remanence acquisition mechanism that remains to be described magnetic contamination experiments using 80 and 40 mt magnets demonstrate that the rem values and extent of modification of the magnetic vector record are mineralogy dependent and this is mostly related to the amount and characteristics of the mineral tetrataenite the complexity of the meteorite records suggest validation of the record as a first step the rem value is the first physical statement that can be made in this validation

the paleoenvironmental significance of spatial distributions of grain size in groundwater recharged lakes a case study in the hinterland of the badain jaran desert northwest china for lakes in desert hinterlands that are not recharged by river runoff sediment input solely comes from wind transport while the processes of sediment transport and deposition in these lakes differ significantly from those with river discharge the spatial distribution of sediment grain size in these groundwater recharged lakes remains largely unknown moreover whether the grain size distribution in these lake sediments can be used as a proxy in the study of past climatic change and environmental evolution studies is unclear in this study five lakes with a range of surface areas that had no runoff recharge were selected from the hinterland of the badain jaran desert of northwestern china and a total of 108 samples of lake surface sediments were collected to examine the spatial distribution of grain size moreover an end member modeling algorithm was used to calculate end members from all grain size measurements our results showed that both the median and mean grain sizes in the lake sediments decreased from the nearshore to the offshore deep water zone however the lowest median and mean grain sizes were not found in the center of the lakes in contrast to lakes recharged by surface runoff the median grain size of sediment in the lake center was negatively correlated with lake level and thus could help reveal lake evolution at low resolutions moreover em1 and em2 were interpreted as wind transported sediment and sediment perturbed by lake waves after wind transport respectively the modal grain size of em1 varied slightly between lakes while changes in the modal grain size of em2 were related to lake area given the positive relationship found between em2 content and lake level changes in the em2 content can serve as a rough indicator of lake level fluctuations at low temporal resolutions

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

discriminating seismic events of the llaima volcano chile based on spectrogram cross correlations abstract the surveillance of active volcanoes around the world has become a critical security issue for many countries requiring a continuous monitoring of seismic signals by analyzing such signals we intend to understand volcanic activities e g explosions eruptions and depressurization and take decisions to reduce the effects and damages to the economy and society of nearby regions active volcanoes constantly produce signals which may then be characterized as data streams making impractical the presence of specialists to monitor and label every activity to overcome this drawback we present a new and straightforward approach to discriminate volcano seismic signals using spectrogram cross correlations spcc in conjunction with the k nearest neighbors algorithm a supervised machine learning strategy experiments were performed on signals collected from the llaima volcano chile and results confirmed the ability of our approach to discriminate events with a sensitivity over 95 for three out of the five classes considered

detecting imminent eruptive activity at mt etna italy in 2007 2008 through pattern classification of volcanic tremor data abstract volcano monitoring aims at the recognition of changes in instrumentally observable parameters before hazardous activity in order to alert governmental authorities among these parameters seismic data in general and volcanic tremor in particular play a key role recent major explosive eruptions such as okmok aleutians and chaiten chile in 2008 and numerous smaller events at mt etna italy have shown that the period of premonitory seismic activity can be short only a few hours which entails the necessity of effective automatic data processing near on line here we present a synoptic pattern classification analysis based on self organizing maps and fuzzy cluster analysis which is applied to volcanic tremor data recorded during a series of paroxysmal eruptive episodes and a flank eruption at etna in 2007 2008 in total eight episodes were analyzed in six of these significant changes in the dynamic regime of the volcano were detected up to 9 h prior to the onset of eruptive activity and long before changes in volcanic tremor amplitude and spectral content became evident in classical analysis in two cases the state transition was

fall classification and cosmogenic records of the sabrum ll6 chondrite the petrographic and chemical characteristics of a fresh indian meteorite fall at sabrum are described its mean mineral composition is defined by olivine fa31 4 orthopyroxene fs25 1 wo2 0 clinopyroxene wo45en45 6fs9 4 and plagioclase an10 6ab83 6or5 8 the meteorite shows moderate shock features which indicate that it belong to the s4 category based on mineralogical and chemical criteria the meteorite is classified as ll6 brecciated veined chondrite several cosmogenic radioisotopes 46sc 7be 54mn 22na and 26al noble gas he ne ar kr and xe nitrogen isotopes and particle tracks density have been measured concentrations of cosmogenic 21ne and 38ar indicate that its cosmic ray exposure is 24 8 ma small amounts of trapped kr and xe consistent with petrologic class 5 6 are present the track density in olivines is found to be 1 3 0 3 x 10 6 cm 2 activities of most of the short lived isotopes are lower than those expected from solar cycle variation 22na 26al 1 12 0 02 is found to be significantly anomalous being approximately 25 lower than expected from the climax neutron monitor data these results indicate that the cosmic ray flux during the terminal segment of the meteoroid orbit was low the activities of 26al and 60co and the track density indicate small meteoroid size with radius 15 cm

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

a new dyke intrusion style for the mount etna may 2008 eruption modelled through continuous tilt and gps data after a recharge phase that began in 2007 on 13 may 2008 a new eruption started on mt etna volcano the final intrusion was very fast accompanied by a violent seismic swarm and marked by ground deformation recorded at permanent tilt and gps stations the violence of the eruptive event generated concern that the eruptive fissures might propagate downslope towards populated areas the ground deformation modelling explains both the mechanism of the intrusion as well as the attempt of the dyke to propagate in the shallower part of the northern sector of the volcano we show that the 2008 intrusion was characterized by a mechanism which is new and different to the ones modelled in previous eruptions following the path of the central conduit in the first part of the intrusion below 1 6 km and then breaking off towards the east in the last shallow part

cross correlation analysis of seismic and volcanic data at mt etna volcano italy seismic data from the mvt sln sesmic station located 7 km from the summit area of mt etna volcano which has been operating steadily for the last two decades have been analysed together with the volcanic activity during the same period cross correlation techniques are used to investigate possible relationships between seismic and volcanic data and to evaluate the statistical significance of the results a number of significant correlations have been identified showing that there is an evident relation between seismic events and flank eruptions and a less clear relation with summit activity which appears more linked to tremor rather than to the low frequency events particularly interesting are the low frequency events whose rate of occurrence increases starting from 17 to 108 days prior to the onset of the flank activity and are candidates for a useful precursor on the other hand a tendency towards the increase in both the duration and the occurrence rate of transients in the volcanic tremor was observed before the onset of summit eruptions as a result of this study different stages in the volcanic activity of mt etna represented by changes in the characteristics of the recorded seismic phenomena are identified

unsupervised neural analysis of very long period events at stromboli volcano using the self organizing maps we have implemented a method based on an unsupervised neural network to cluster the waveforms of very long period vlp events associated with explosive activity at the stromboli volcano southern italy stromboli has several active vents in the summit area producing together more than 200 explosions day we applied this method to investigate the relationship between each vent and its associated vlp explosive waveform we selected 147 vlp events recorded between november and december 2005 when digital infrared camera recordings were available from a visual inspection of the infrared camera images we classified the vlps on the basis of which vent produced each explosion we then applied the self organizing map som an unsupervised neural technique widely applied in data exploratory analysis to cluster the vlps on the basis of their waveform similarity our analysis demonstrates that the most recurrent vlp waveforms are usually generated by the same vent some exceptions occurred however in which different waveforms are associated with the same vent as well as different vents generating similar waveforms this suggests that the geometry of the upper conduit vent system plays a role in shaping the recurring vlp events whereas occasional modest changes in the source process dynamics produce the observed exceptions

spectro temporal features applied to the automatic classification of volcanic seismic events abstract feature extraction and selection are very relevant processes in the design of automatic classifiers in the context of volcanic seismic signal classification most of the features presented in the literature have been extracted separately from a single domain such as time or frequency however spectrograms which combine time and frequency information are widely used by experts during the classification of manual seismic events this paper proposes to evaluate the performance of classifiers trained with features extracted from the spectro temporal domain individually or combined with other conventional features the parameters were extracted from the spectrogram based on a curve which combines the high energy components and the frequency bandwidth information through the duration of the event the tests were performed at the llaima volcano and seismic events were classified into four classes long period tremor volcano tectonic and tectonic using a database of signals recorded between the years 2009 and 2017 the main achievements of this study were the reduction of more than 70 of the error and false positive rates and also a reduction of approximately 30 of the number of features compared with a baseline established in previous studies thus the inclusion of spectro temporal information was considered relevant to complement the conventional features and to support classification

petrogenesis of acapulcoites and lodranites a shock melting model abstract acapulcoites are modeled as having formed by shock melting cr like carbonaceous chondrite precursors the degree of melting of some acapulcoites was low enough to allow the preservation of 3 6 vol relict chondrules shock effects in acapulcoites include veins of metallic fe ni and troilite polycrystalline kamacite fine grained metal troilite assemblages metallic cu and irregularly shaped troilite grains within metallic fe ni while at elevated temperatures acapulcoites experienced appreciable reduction because graphite is present in some acapulcoites and lodranites it seems likely that carbon was the principal reducing agent reduction is responsible for the low contents of olivine fa 4 14 mol and low ca pyroxene fs 3 13 mol in the acapulcoites the observation that in more than two thirds of the acapulcoites the fa value is lower than the fs value in contrast to the case for equilibrated ordinary chondrites the low feo mno ratios in acapulcoite olivine 16 18 compared to 32 38 in equilibrated h chondrites the relatively high modal orthopyroxene olivine ratios e g 1 7 in monument draw compared to 0 74 in h chondrites and reverse zoning in some mafic silicate grains lodranites formed in a similar manner to acapulcoites but suffered more extensive heating loss of plagioclase and loss of an fe ni s melt acapulcoites and lodranites experienced moderate post shock annealing presumably resulting from burial beneath material of low thermal diffusivity the annealing process repaired damaged olivine crystal lattices lending acapulcoites and lodranites the appearance of unshocked i e shock stage s1 rocks any high pressure phases that may have formed during initial shock reverted to their low pressure polymorphs during annealing some samples were subsequently shocked again several acapulcoites reached shock stage s2 levels alh 84190 reached s3 and the lodranite mac 88177 reached s5

flood stratigraphies in lake sediments a review abstract records of the frequency and magnitude of floods are needed on centennial or millennial timescales to place increases in their occurrence and intensity into a longer term context than is available from gauged river flow and historical records recent research has highlighted the potential for lake sediment sequences to act as a relatively untapped archive of high magnitude floods over these longer timescales abyssal lake sediments can record past floods in the form of coarser grained laminations that reflect the capacity for river flows with greater hydrodynamic energy to transport larger particles into the lake this paper presents a framework for investigating flood stratigraphies in lakes by reviewing the conditioning mechanisms in the lake and catchment outlining the key analytical techniques used to recover flood records and highlighting the importance of appropriate field site and methodology selection the processes of sediment movement from watershed to lake bed are complex meaning relationships between measureable sedimentary characteristics and associated river discharge are not always clear stratigraphical palaeoflood records are all affected to some degree by catchment conditioning fluvial connectivity sequencing of high flows delta dynamics as well as within lake processes including river plume dispersal sediment focussing re suspension and trapping efficiency with regard to analytical techniques the potential for direct e g laser granulometry and indirect e g geochemical elemental ratios measurements of particle size to reflect variations in river discharge is confirmed we recommend care when interpreting fine resolution geochemical data acquired via micro scale x ray fluorescence xrf core scanning due to variable down core water and organic matter content altering x ray attenuation we also recommend accounting for changes in sediment supply through time as new or differing sources of sediment release may affect the hydrodynamic relationship between particle size and or geochemistry with stream power where these processes are considered and suitable dating control is obtained discrete historical floods can be identified and characterised using palaeolimnological evidence we outline a protocol for selecting suitable lakes and coring sites that integrates environmental setting sediment transfer processes and depositional mechanisms to act as a rapid reference for future research into lacustrine palaeoflood records we also present an interpretational protocol illustrating the analytical techniques available to palaeoflood researchers to demonstrate their utility we review five case studies of palaeoflood reconstructions from lakes in geographically varied regions these show how lakes of different sizes and geomorphological contexts can produce comprehensive palaeoflood records these were achieved by consistently applying site validated direct and proxy grain size measurements well established chronologies validation of the proxy process interpretation and calibration of the palaeoflood record against instrumental or historical records

seismic and infrasound signals at mt etna modeling the north east crater conduit and its relation with the 2008 2009 eruption feeding system abstract on 13 may 2008 an eruption began at mt etna from an eruptive fissure that opened on the upper eastern flank of the volcano during 12 13 may 157 infrasonic events together with the related seismic transients were collected we carried out several analyses to obtain dominant frequencies pseudospectrograms peak to peak amplitudes source locations and time lags between infrasonic and seismic events spectra of the infrasonic events show two main spectral peaks in the frequency bands 0 4 0 7 hz and 1 5 2 0 hz respectively both infrasonic and seismic events were separately located below the north east crater where no eruptive activity was observed moreover significant changes in infrasound spectral content as well as in the infrasonic seismic lags were found a few hours before the beginning of the eruption on the basis of the collected information the infrasound source mechanism was modeled as a superposition of pipe and helmholtz resonance also leading to outline the geometry of the shallower portion of the north east crater plumbing system the occurrence of these seismo infrasonic events together with other geological and geophysical evidences led us to inferring a direct link between north east crater activity and the eruptive fissure further based on variations over time of both spectral features and seismic infrasonic time lag shallowing phenomena of the free magma column inside north east crater conduit were hypothesized such an uprise of magma was likely caused by a pressure increase inside the plumbing system occurring before the beginning of the 2008 2009 eruption

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

a 1600 yr seasonally resolved record of decadal scale flood variability from the austrian pre alps we present a record of extreme spring summer runoff events for the past 1600 yr preserved in the varved sediments of lake mondsee austrian pre alps combined sediment microfacies analyses and high resolution micro x ray fluorescence element scanning allow us to identify 157 detrital event layers deposited in spring summer and to discriminate between regional flood and local debris flow deposits higher spring summer flood activity with a mean event recurrence of 3 5 yr occurred in several well confined multidecadal episodes during the dark ages cold period and medieval time a d 450 480 590 640 700 750 and 1140 1170 as well as during the early little ice age lia a d 1300 1330 and 1480 1520 in contrast lowest spring summer flood activity with an event recurrence of only 30 100 yr is observed during the medieval climate anomaly a d 1180 1300 and the coldest interval of the lia a d 1600 1700 these findings indicate a complex relationship between temperature conditions and extreme hydro meteorological events and suggest that enhanced summer mediterranean cyclogenesis triggers large scale floods in the northeast alps during climatic transitions the lake mondsee data demonstrate the climatic sensitivity of spring summer floods and prove the potential of varved sediment records to investigate the impact of changing climate boundary conditions on seasonal flood activity for pre instrumental time

the meteoritical bulletin no 84 2000 august meteoritical bulletin no 84 lists information for 1341 newly classified meteorites comprising 842 from antarctica 341 from africa 66 from australia 48 from asia including 42 from the arabian peninsula 38 from north america 4 from europe and 2 from south america information is provided for 11 recent falls bilanga devri khera djoumine guangmingshan kitchener kobe leighlinbridge sabrum songyuan tagish lake and vissannapeta 4 martian meteorites dar al gani 670 735 dhofar 019 los angeles and sayh al uhaymir 005 008 3 lunar meteorites northwest africa 032 dhofar 025 and 026 an ungrouped enstatite rich meteorite zaklodzie 11 iron meteorites and a wide variety of other interesting stony meteorites including ck cm co cr cv r enstatite and unequilibrated ordinary chondrites primitive achondrites hed achondrites ureilites and aubrites

evolution and classification of acapulcoites and lodranites from a chemical point of view we examined 15 bulk samples of the acapulcoite lodranite clan for their major minor and trace element concentrations using inaa techniques among the analyzed meteorites are 2 new acapulcoites dhofar dho 290 thiel mountains til 99002 as well as an additional acapulcoite that has been described previously only in very brief form graves nunataks gra 98028 the petrographic attributes of these 3 samples are addressed thoroughly we also include petrographic information on 2 acapulcoites from africa northwest africa nwa 725 and nwa 1058 in general our study strongly supports the widely accepted idea that acapulcoites and lodranites evolved through partial melting and melt migration of metal sulfide phases and plagioclase furthermore we concur with previous researchers that the original bimodal classification scheme for acapulcoites and lodranites proves to be too simple based on our data set we introduce an alternative extended scheme with respect to their elemental distribution patterns we distinguish 5 subtypes comprising primitive typical transitional and enriched acapulcoites on one hand and lodranites on the other the chemical distinction between the primitive typical and transitional acapulcoites is rather subtle and gradual it stands in contrast to the clear modifications observed for the signatures of the enriched acapulcoites and the lodranites the definition of subcategories basically reflects the concentrations of 2 key elements k and se we note however that the assignment of subgroups may not be exclusively inferred from elemental abundances but should also consider additional petrographic information

devri khera a new l6 chondrite the devri khera meteorite fell on 1994 october 30 in the jhalwar district of rajasthan northwestern india the texture mineralogy and mineral and bulk compositions show that devri khera is an l6 chondrite of shock facies s4

noble gases in enstatite chondrites ii the trapped component the trapped noble gas record of 57 enstatite chondrites e chondrites has been investigated basically two different gas patterns have been identified dependent on the petrologic type all e chondrites of type 4 to 6 show a mixture of trapped common chondritic rare gases q and a subsolar component range of elemental ratios for e4 6 chondrites 36ar 132xe 582 270 and 36ar 84kr 242 88 e3 chondrites usually contain q gases but also a composition with lower 36ar 132xe and 36ar 84kr ratios which we call sub q 36ar 132xe 37 0 18 0 and 36ar 84kr 41 7 18 1 the presence of either the subsolar or the sub q signature in particular petrologic types cannot be readily explained by parent body metamorphism as postulated for ordinary chondrites we therefore present a different model that can explain the bimodal distribution and composition of trapped heavy noble gases in e chondrites trapped solar noble gases have been observed only in some e3 chondrites about 30 of each group eh3 and el3 chondrites amounting to 9 of all analyzed e chondrites show the solar signature notably only one of those meteorites has been explicitly described as a regolith breccia

a multiparameter approach to volcano monitoring based on 4d analyses of seismo volcanic and acoustic signals the 2008 mt etna eruption 1 volcanic tremor and low frequency events together with infrasound signals can represent important precursory phenomena of eruptive activity because of their strict relationship with eruptive mechanisms and with fluid flows through the volcano s feeding system important variations of these seismo volcanic and infrasound signals recorded at mt etna volcano occurred both in the medium and short term before the eruption that took place on 13 may 2008 the most significant changes were observed in the frequency content and location of lp events as well as in volcanic tremor location that allowed us to track the magma pathway feeding the 2008 eruptive activity the infrasound showed three different families of events linked to the activity of the three active vents north east crater south east crater and the eruptive fissure the seismic and infrasonic variations reported corroborated by ground deformations variations help to develop a quantitative prediction and early warning system for effusive and or explosive eruptions

magnetic classification of stony meteorites 2 non ordinary chondrites a database of magnetic susceptibility measurements on different non ordinary chondrites c e r and ungrouped populations is presented and compared to our previous similar work on ordinary chondrites it provides an exhaustive study of the amount of iron nickel magnetic phases essentially metal and magnetite in these meteorites in contrast with all the other classes cm and cv show a wide range of magnetic mineral content with a two orders of magnitude variation of whether this is due to primary parent body differences metamorphism or alteration remains unclear c34 and c2 yield similar values to the ones shown by ck and cm respectively by order of increasing the classes with well grouped are r co ck ci kak cr e ch cb based on magnetism eh and el classes have indistinguishable metal content outliers that we suggest may need to have their classifications reconsidered are acfer 202 co elephant moraine eet 96026 c45 meteorite hills met 01149 and northwest africa nwa 521 ck asuka a 88198 lapaz icefield lap 031156 and sahara 98248 r values can also be used to define affinities of ungrouped chondrites and propose pairing particularly in the case of cm and cv meteorites

dhofar 081 a new lunar highland meteorite the lunar meteorite dhofar 081 found as a single fragment of 174 g in the dhofar region of oman is a shocked feldspathic fragmental highland breccia dominated by anorthosite rich lithic and mineral clasts embedded into a fine grained mostly shock melted clastic matrix major mineral phases in the bulk rock are ca rich plagioclase an96 5 99 5 pyroxene fs21 9 46 2wo3 0 41 4 and olivine fa29 3 47 8 accessory phases include fe ni metal ilmenite and ti cr rich spinel dhofar 081 contains subordinate crystalline fragments of large anorthosites intersertal impact melt rocks microporphyritic impact melt breccias dark fine grained impact melt breccias large cataclastic feldspars and irregularly shaped brown glass clasts mafic components are rare and no genuine regolith components were found in the sections studied minerals in dhofar 081 show homogeneously distributed shock features intergranular recrystallization strong fracturing and mosaicism in feldspar as well as a high density of mostly irregular fractures in pyroxene and olivine localized impact melting caused by one or several impacts led to a strong lithification based on these effects an equilibration shock pressure of about 15 20 gpa is estimated for the strongest shock event in dhofar 081 devitrification of the glassy material in the rock indicates thermal annealing after shock melting suggesting that the 15 20 gpa shock event predated the ejection event according to the concentrations of implanted solar noble gases dhofar 081 represents a polymict clastic breccia deposit with possibly a minor regolith component a similar noble gas record of dhofar 081 and macalpine hills 88104 05 suggests the possibility of a source crater pairing of both meteorites as indicated by noble gas measurements pairing of dhofar 081 with the other lunar meteorites found in oman dhofar 025 and dhofar 026 is unlikely

noble gases in enstatite chondrites i exposure ages pairing and weathering effects cosmic ray exposure ages calculated from cosmogenic noble gas nuclides are reported for 57 enstatite e chondrites 43 of them were measured for the first time with a total of 62 individual e chondrites literature and this data corrected for pairing the observed spectrum of ages ranges between 0 07 and 66 ma three clusters seem to develop at about 3 5 8 and 25 ma respectively since the uncertainty of ages is estimated to be 20 in contrast to 10 to 15 for ordinary chondrites and the number of examined samples is still comparatively small these peaks have to be confirmed by more measurements regarding the two subgroups eh and el chondrites no systematic trend is apparent in the distribution of cosmic ray exposure ages several e chondrites yield significantly lower 38ar ages compared to those calculated from cosmogenic 3he and 21ne for these e chondrites we suggest a reduction of cosmogenic 38ar as a result of weathering in order to prove the possible influence of terrestrial alteration on the cosmogenic noble gas record of e chondritic material we simulated terrestrial weathering in an experiment of 12 weeks duration the treatment showed that a significant amount of cosmogenic 38ar is lost on earth by the influence of water

application of support vector machine to the classification of volcanic tremor at etna italy we applied an automatic pattern recognition technique known as support vector machine svm to classify volcanic tremor data recorded during different states of activity at etna volcano italy the seismic signal was recorded at a station deployed 6 km southeast of the summit craters from 1 july to 15 august 2001 a time span encompassing episodes of lava fountains and a 23 day long effusive activity trained by a supervised learning algorithm the classifier learned to recognize patterns belonging to four classes i e pre eruptive lava fountains eruptive and post eruptive training and test of the classifier were carried out using 425 spectrogram based feature vectors following cross validation with a random subsampling strategy svm correctly classified 94 7 2 4 of the data the performance was confirmed by a leave one out strategy with 401 matches out of 425 patterns misclassifications highlighted intrinsic fuzziness of class memberships of the signals particularly during transitional phases

ca al rich inclusions in rumuruti r chondrites rumuruti chondrites r chondrites constitute a well characterized chondrite group different from carbonaceous ordinary and enstatite chondrites many of these meteorites are breccias containing primitive type 3 fragments as well as fragments of higher petrologic type ca al rich inclusions cais occur within all lithologies here we present the results of our search for and analysis of al rich objects in rumuruti chondrites we studied 20 r chondrites and found 126 ca al rich objects 101 cais 19 al rich chondrules and 6 spinel rich fragments based on mineralogical characterization and analysis by sem and electron microprobe the inclusions can be grouped into six different types 1 simple concentric spinel rich inclusions 42 2 fassaite rich spherules 3 complex spinel rich cais 53 4 complex diopside rich inclusions 5 al rich chondrules and 6 al rich spinel rich fragments the simple concentric and complex spinel rich cais have abundant spinel and based on the presence or absence of different major phases fassaite hibonite na al cl rich alteration products can be subdivided into several subgroups although there are some similarities between cais from r chondrites and inclusions from other chondrite groups with respect to their mineral assemblages abundance and size the overall assemblage of cais is distinct to the r chondrite group some ca al rich inclusions appear to be primitive e g low feo contents in spinel low abundances of na al cl rich alteration products abundant perovskite whereas others were highly altered by nebular and or parent body processes e g high concentrations of feo and zno in spinel ilmenite instead of perovskite abundant na al cl rich alteration products there is complete absence of grossite and melilite which are common in cais from most other groups cais from equilibrated r chondrite lithologies have abundant secondary ab rich plagioclase oligoclase and differ from those in unequilibrated type 3 lithologies which have nepheline and sodalite instead

the failed eruption of mt etna in december 2005 evidence from volcanic tremor analyses 1 strong changes in seismic radiation comparable to those preceding and or accompanying eruptive activity in recent years were recorded at mt etna volcano italy from november 2005 to january 2006 the amplitude of volcanic tremor peaked in mid december 2005 after a continuous slow increase from august 2005 onward during which neither effusive nor paroxysmal activity was observed by volcanologists and alpine guides during this time span the centroid locations of volcanic tremor moved toward the surface more and more clustered below the summit craters the application of pattern classification analysis based on self organizing maps and fuzzy clustering to volcanic tremor data highlighted variations in the frequency domain as well these changes were temporally associated with ground deformation variations as indicative of a mild inflation of the summit of the volcano and with a conspicuous increase in the so2 plume flux emission overall we interpret this evidence as the result of recharging of the volcanic feeder at depth 3 km below sea level during which magma did not reach the shallow plumbing system

what happens to in soil radon activity during a long lasting eruption insights from etna by multidisciplinary data analysis we analyze short to long term changes from days to months in radon rn activity measured nearby 2 km the eruptive fractures that fed a lava effusion at mt etna italy between 13 may 2008 and 6 july 2009 the n120 140 e eruptive fractures opened between 3050 and 2620 m above sea level before a dike forming intrusion fed the 14 month long lava emission our high rate data streams include rn ambient parameters barometric pressure and soil temperature and seismic data earthquakes and volcanic tremor recorded from january 2008 to july 2009 the analysis highlights repeated episodes of rock fracturing related to seismic swarms and vigorous gas pulses and peak values in rn emissions maximum 4 1x105 bq m3 on 16 november 2008 which we interpreted in a conceptual model as the response to inputs from the magmatic system during the eruption this multidisciplinary study i provides evidence of a close relationship between rn emission at a fumarole near the summit active craters and local earthquakes and ii enables exploring the important role of the volcanic source on the temporal development of the rn flux which may account for the much higher 94 m day ascent speed of the rn carrier vapor than diffusion the close location of rn probes to the active conduits along with the application of our multidisciplinary approach may shed new light on the internal dynamics of other active volcanoes worldwide

the 4 5 september 2007 lava fountain at south east crater of mt etna italy abstract continuous monitoring of paroxysmal eruptions at mt etna italy is performed from the istituto nazionale di geofisica e vulcanologia sezione di catania in recent years this activity has allowed us to study fallout deposits and track the evolution of eruptive phases this communication reports on the paroxysm that occurred in the afternoon of 4 september 2007 when a powerful lava fountain started from south east crater at the summit of etna the fountaining formed a plume up to 2 km high for almost 12 h causing abundant tephra fallout in the eastern sector of the volcano and emplacement of a thick about 4 km long clastogenic lava flow extensive area collection of tephra samples from the fallout deposit was performed within a few hours after the end of the paroxysm we calculated a total erupted volume of 3 92 4 9 10 5 m 3 and a total grain size fitted by a gaussian distribution with the mode of 0 and equal to 1 3 the total volume of the clastogenic lava flow deposit that resulted was 2 4 10 6 m 3 the systematic study of paroxysms at etna helps to better investigate etnean type lava fountains and to improve the classification of explosive activity on basaltic volcanoes

pattern recognition applied to seismic signals of llaima volcano chile an evaluation of station dependent classifiers abstract automatic pattern recognition applied to seismic signals from volcanoes may assist seismic monitoring by reducing the workload of analysts allowing them to focus on more challenging activities such as producing reports implementing models and understanding volcanic behaviour in a previous work we proposed a structure for automatic classification of seismic events in llaima volcano one of the most active volcanoes in the southern andes located in the araucania region of chile a database of events taken from three monitoring stations on the volcano was used to create a classification structure independent of which station provided the signal the database included three types of volcanic events tremor long period and volcano tectonic and a contrast group which contains other types of seismic signals in the present work we maintain the same classification scheme but we consider separately the stations information in order to assess whether the complementary information provided by different stations improves the performance of the classifier in recognising seismic patterns this paper proposes two strategies for combining the information from the stations i combining the features extracted from the signals from each station and ii combining the classifiers of each station in the first case the features extracted from the signals from each station are combined forming the input for a single classification structure in the second a decision stage combines the results of the classifiers for each station to give a unique output the results confirm that the station dependent strategies that combine the features and the classifiers from several stations improves the classification performance and that the combination of the features provides the best performance the results show an average improvement of 9 in the classification accuracy when compared with the station independent method

is a regional flood signal reproducible from lake sediments the evolution of flood activity with global warming remains uncertain to better assess flood climate relationships lake sediments are increasingly being investigated because they could provide regional flood histories long enough to cover past climate changes however site specific sedimentary processes may bias flood reconstructions the aim of this article is to investigate these effects through the reconstruction of two distinct flood records from independent neighbouring sedimentary basins of the same lake lake allos in the mediterranean french alps i e under the same climate conditions understanding of sedimentary processes is crucial in order to adapt the sampling strategy and the flood intensity proxy to each sedimentary system and thereby reconstruct a complete and reliable flood history thanks to this detailed approach the main trends of the regional flood variability can be reproduced i e periods of high flood frequency ranges of flood frequency values and timing of the most intense events in detail some differences appeared associated to the various stream capacities to erode and transport flood sediments to the lake system implying variable sensitivity of sedimentary systems in recording floods comparing regional flood records based on independent sedimentary systems from similar environments could thus be a complementary approach to assessing past flood intensity such an approach could open particularly interesting perspectives because reconstructing the long term evolution of flood intensity is a key challenge in the geosciences

a global study of volcanic infrasound characteristics and the potential for long range monitoring abstract volcanic infrasound from explosive eruptions is detectable at distances up to 1000 s of km and is often recorded on the international monitoring system ims infrasound network though infrasound produced by individual volcanoes has previously been studied more general relationships between infrasound characteristics and eruption parameters remain unclear therefore using a dataset comprising 110 events at 39 globally distributed volcanoes we assess the ability of the ims to monitor remote volcanoes and investigate whether volcanic infrasound exhibits consistent trends across a range of eruption styles and intensities acoustic pressure amplitude and frequency content of the volcanic infrasound were measured and acoustic energy was also calculated these were compared along with the maximum distance of detection for each event to the maximum plume height reported for the event which was used as a proxy for event intensity of the events investigated 62 were detected by at least one infrasound station the maximum distance at which an event was detected generally increased with the plume height and infrasound produced during the eruption of manam png in january 2005 which produced a plume which rose over 20 km above the summit was detected at a distance of 10 671 km total acoustic energy and acoustic pressure amplitude corrected for geometrical spreading increased with plume height whilst the lowest frequency present in the volcanic infrasound decreased additionally relationships seen between infrasound characteristics and eruption plume height indicate that analyses of this data alone could constrain vital estimates of plume heights for otherwise un observed eruptions taken together these findings indicate that if made available for this purpose in the future the ims infrasound network could complement existing monitoring techniques by detecting and characterising eruptions at remote volcanoes which often have no local monitoring networks