sulfur dioxide from nevado del ruiz volcano colombia total flux and isotopic constraints on its origin abstract nevado del ruiz volcano has been releasing extraordinarily large volumes of sulfur dioxide gas from its arenas crater since september 1985 and probably since the renewal of volcanic activity began in late 1984 the combined release from eruptive and passive flux has been approximately 3 4 1 0 10 6 metric tons in the four years after november 1984 this value combined with data of others on pre eruption sulfur content of the magma allows the calculation of a minimum required volume of magma of 0 92 km 3 consideration of the continued high flux and typical ratios of erupted to degassed magma indicate that the true minimum volume of magma involved is probably at least 4 6 9 2 km 3 a systematic study of the various species of sulfur in the volcanic plume and the hydrothermal system has provided a characterization of the geochemistry and sulfur isotopic variation consideration has been given to five potential sources of the sulfur dioxide dissolution of subvolcanic evaporites remobilization and oxidation of native sulfur within summit crater fumaroles large scale release from the hydrothermal system by reduction of sulfate or water rock interaction assimilation and oxidation of a pre existing sulfide deposit and magmatic volatiles the data are most realistically explained by the passage of magmatic gas through the hydrothermal system with some disproportionation of sulfur dioxide to produce the high sulfate content and low ph of the waters this model is also most consistent with the distribution of acid sulfate chloride hot springs high chloride and fluoride content of the hydrothermal waters sulfide deposition within the volcanic pile and the transient increase in sulfate content of the acid sulfate chloride hot springs that reached a maximum approximately one year after the november 1985 eruption the magmatic model is in apparent conflict with the absence of general deformation from the time that data began to be collected about one week before the eruption until the time this manuscript was finalized september 1989 although this conflict cannot be resolved with certainty it is noted that the absence of deformation is only an indication of the lack of magma movement not of the absence of magma an alternative magmatic model considers the available geological data and proposes that the system is related to a large scale caldera in this model the degassing is related to a long term process of exsolution of magmatic volatiles from a large volume of crystallizing magma left from the construction of modern ruiz this model can better explain the combined geological and geophysical data as well as the geochemical and isotopic data the nature of the degassing data at ruiz is interesting because it is an example of an explosive eruption cycle in which the gas flux is actually dominated by passive release the nature of the degassing allows us to hypothesize that some major change in the system occurred in april may 1986 and to predict that the present high flux can be expected to last for another decade

material balance in alpine orogeny recent geophysical data are combined with older information for an updated picture of alpine kinematics using semiquantitative considerations of material balance in the alps a conventional pile of thin peel nappes is disrupted by a central longitudinal system of steep faults and steeply limbed folds both affecting disharmoniously the entire edifice of otherwise flat lying nappes it is particularly from late tertiary phases of deformation that structures of the second type the insubric system with the insubric line and the belt of late alpine windows acquired prominence for the present aspect of the alps these late structures formed as a dextrally transpressive intracontinental branch of the africa europa plate boundary mostly between areas of extension early motions in the late cretaceous to the late eocene were probably responsible for at least half of the 300 km dextral displacement required for the palinspastic restoration of the inner west carpathians and the dinarides during oligocene extension the late alpine batholiths intruded in a belt roughly along the insubric line while deep crustal and lithospheric roots were destroyed in the latest oligocene to middle miocene the adriatic plate moved dextrally to the west along the insubric transfer fault from its frontal insubric indenter a lower crust upper mantle flake probably first obducted in the cretaceous was detached and wedged into the penninic nappes of the western alps bird s head of the ivrea body both the northern and the southern transfer faults of the insubric indenter were disrupted and inactivated by late miocene to later events the giudicarie and neo north apennine events instead of the inactivated insubric fault the windows belt of en echelon folds assumed the role of dextral transpression all of these successive zones of motion are entangled in the ligurian knot largely hidden under the sea or young sediments a large part of the pre alpine crust and practically the whole mantle were subducted only in some cases were high pressure rocks of shallow continental origin re obducted the lithospheric root of the neo alps is largely contained in a vertical slab under the alps but some parts seem to have been removed and others disharmonically displaced with respect to the surface structures

an evaluation of volcanic cloud detection techniques during recent significant eruptions in the western ring of fire we examined recent volcanic cloud events in the western pacific and indonesian area to validate the performance of remote sensing techniques used to support the international airways volcano watch iavw five events were considered during which eruptions from eight volcanoes injected ash into the upper troposphere or lower stratosphere for one of the eruptions at miyakejima japan at least five aircraft encountered volcanic ash clouds and the cost to three operators alone exceeded us 12 000 000 in aircraft repairs diversions and lost operating time we performed reverse absorption and pattern analysis using gms 5 vissr modis and avhrr data and we examined toms so2 and aerosol index data surface based observations pilot reports and dispersion model output our results verify that the introduction of reverse absorption using the geostationary gms 5 platform significantly enhanced our capacity to monitor volcanic ash clouds in the region in one case we tracked an eruption cloud for approximately 80 h the primary impediment to remote monitoring is the presence of overlying cloud or substantial amounts of ice within the volcanic clouds toms data showed success in identifying volcanic clouds during these conditions but was limited by the infrequency of observations more effective future operation of the iavw relies on developing complementary methods of volcanic cloud remote sensing and greatly increasing the amount and quality of available surface and air observations including observations of precursor activity an understanding of the likely future limitations of remote sensing techniques will aid in the refining of iavw procedures

source constraints of tungurahua volcano explosion events the most recent eruptive cycle of tungurahua volcano began in may 2004 and reached its highest level of activity in july 2004 this activity cycle is the last one of a series of four cycles that followed the reawakening and major eruption of tungurahua in 1999 between june 30 and august 12 2004 three temporary seismic and infrasonic stations were installed on the flanks of the volcano and recorded over 2 000 degassing events the events are classified by waveform character and include explosion events the vast majority spanning three orders of pressure amplitudes at 3 5 km from the vent 0 1 180 pa jetting events and sequences of repetitive infrasonic pulses called chugging events travel time analysis of seismic first arrivals and infrasonic waves indicates that explosions start with a seismic event at a shallow depth 200 m followed 1 s later by an out flux of gas ash and solid material through the vent cluster analysis of infrasonic signals from explosion events was used to isolate four groups of similar waveforms without apparent correlation to event size location or time the clustering is thus associated with source mechanism and probably spatial distribution explosion clusters do not exhibit temporal dependence

lithospheric stress states predicted from long term tectonic models influence of rheology and possible application to taiwan abstract the long term stress state of the lithosphere results from a combination of boundary forces surface loads and tractions from mantle flow here we have employed a numerical technique which allows for the self consistent treatment of the interaction between the lithosphere and mantle and takes into account the deformation of the free surface we have used this to study lithospheric dynamics in order to gain insights on the present day conditions of stress and deformation of the lithosphere our numerical approach takes the observed topography and far field plate velocities as input and computes the resultant deformation as a function of the rheological stratification our model application is inspired by taiwan tectonics stress data and earthquake focal mechanisms indicate that the upper crust in taiwan may be predominantly under compression the recent pingtung earthquake in 12 26 2006 however suggests that the sub moho mantle lithosphere under southern taiwan may be under extension if this earthquake indeed represents the local state of stress this raises the question as to why extension and compression can occur simultaneously in this region for addressing this issue we have performed a number of numerical simulations in which we studied the effects of rheological stratification boundary conditions and geometry on the stress state and lithospheric dynamics we have employed both layered viscosity models and models in which we use laboratory based non newtonian and temperature dependent creep laws results show that the rheological stratification plays an important role in lithospheric deformation the relatively hot lithospheric thermal state in taiwan makes it likely that part of the lower crust is relatively weak which results in decoupling from surface near deformation with deformation at depth bending of a subducting slab underneath taiwan causes an extensional stress state in the sub moho mantle lithosphere whereas the collision of the philippine sea plate with the eurasian margin is responsible for a compressional state of stress in the crust it is demonstrated that models with a weak lower crust are also in reasonable agreement with available gps data as well as with constraints on uplift rates from long term geodynamic modelling studies

stress state in the cuu long and nam con son basins offshore vietnam abstract the results presented in this paper are the first published estimates of the complete stress tensor in the cuu long and nam con son basins offshore vietnam we analysed in situ stress and pore pressure fields in the sedimentary formations using data from petroleum exploration and production wells to evaluate the stress state in these basins the data were obtained from the seafloor to 4300 m burial depth and include both hydrostatic and overpressured sections minimum horizontal stresses were obtained from extended leak off tests and mini fracture tests maximum horizontal stresses were estimated from drilling induced fracture parameters and borehole breakout widths in twelve wells using rock properties measured in the laboratory or estimated empirically from wireline logs seven data points are located in sediments and seventeen data points in igneous basement rocks at depths greater than 3000 m the estimated magnitudes of h are 70 110 of the v magnitudes considering the errors in the stress magnitude estimates their relative magnitudes suggest that a borderline normal strike slip stress regime presently exists in normally pressured sequences of the nam con son and cuu long basins of the twenty four data points twenty have effective stress ratios at a critical stress state for faulting on the assumption that there are faults present that are optimally oriented for failure with friction coefficients of 0 5 the results suggest that the stress state in these basins is generally critical

large scale crustal heterogeneities and lithospheric strength in cratons abstract the rheology and thermal structure of the continental lithosphere are intimately linked in old cratons the effective elastic thickness of the lithosphere has been estimated by various spectral inverse methods based on the correlation between topography and gravity anomalies estimates vary within a very large range from 40 km to 120 km depending on the method used in this paper we use forward models to account for lateral variations in mechanical properties and their effect on the equivalent elastic thickness eet of the lithosphere from these models which allow brittle elastic ductile rheologies and mechanical discontinuities faults we have calculated the strain stress distributions and displacement fields vertical integration of the stress permits a local determination of the effective elastic thickness the computed displacements were used to calculate related bouguer and free air gravity anomalies and compare them with the observations the analysis is applied to the 2000 ma kapuskasing uplift in the superior province of the canadian shield where the presence of a high density block in the upper crust is due to the upthrusting of midcrustal rocks along a major thrust fault the study shows that the stability of this structure on geologic time scales requires a strong lower crustal rheology a cold geotherm and the fault to be healed this study also shows that because of stress dependence of the non linear rheology crustal heterogeneities may cause significant 40 local reductions of the lithospheric strength away from the kapuskasing structure the average strength of the lithosphere remains high eet 100 km conventional methods for estimating the elastic thickness would not resolve such local strength reductions in cratons but would predict depending on the method used highly overestimated or instead underestimated eet

tectonic evolution of a continental collision zone a thermomechanical numerical model we model evolution of a continent continent collision and draw some parallels with the tectonic evolution of the himalaya we use a large scale visco plasto elastic thermomechanical model that has a free upper surface accounts for erosion and deposition and allows for all modes of lithospheric deformation for quartz olivine rheology and 60 mm yr convergence rate the continental subduction is stable and the model predicts three distinct phases during the phase 1 120 km or 6 of shortening deformation is characterized by back thrusting around the suture zone some amount of delaminated lower crust accumulates at depth during phase 2 120 km 420 km or 6 22 of shortening this crustal root is exhumed medium to high grade rocks along a newly formed major thrust fault this stage bears similarities with the period of coeval activity of the main central thrust and of the south tibetan detachment between 20 16 myr ago during phase 3 420 km or 22 of shortening the crust is scraped off from the mantle lithosphere and is incorporated into large crustal wedge deformation is localized around frontal thrust faults this kinematics should produce only low to medium grade exhumation this stage might be compared with the tectonics that has prevailed in the himalaya over the last 15 myr allowing for the formation of the lesser himalaya the experiment is conducted at constant convergence rate which implies increasing compressive force considering that this force is constant in nature this result may be equivalent to a slowing down of the convergence rate as was observed during the india asia collision

ecuadorian andes volcanism a review of late pliocene to present activity abstract this article provides background information about ecuador s general volcanic setting as an introduction to the numerous articles in this special issue of the journal dealing with the many facets of ecuadorian volcanism it also provides a brief description of ecuador s physiography as well as its geodynamic setting a comprehensive bibliography is included as a guide to further reading the ecuadorian andes contain at least 20 volcanoes active during the holocene several reach altitudes of 5000 to 6000 m and are glacier clad eleven have erupted in pre columbian and historic times and have greatly affected local populations and caused fatalities

satellite based constraints on explosive so2 release from soufriere hills volcano montserrat 1 numerous episodes of explosive degassing have punctuated the 1995 2009 eruption of soufriere hills volcano shv montserrat often following major lava dome collapses we use ultraviolet uv and infrared ir satellite measurements to quantify sulfur dioxide so2 released by explosive degassing which is not captured by routine ground based and airborne gas monitoring we find a total explosive so2 release of 0 5 tg which represents 6 of total so2 emissions from shv since july 1995 the majority of this so2 0 4 tg was vented following the most voluminous shv dome collapses in july 2003 and may 2006 based on our analysis we suggest that the so2 burden measured following explosive disruption of lava domes depends on several factors including the instantaneous lava effusion rate dome height above the conduit and the vertical component of directed explosions space based so2 measurements merit inclusion in routine gas monitoring at shv and other dome forming volcanoes

deep seismic reflection profiling in the swiss alps explosion seismology results for line nfp 20 east in september 1986 a 120 km long seismic line was recorded through the swiss alps the line traverses major units involved in thin and thick skinned alpine tectonics our preliminary interpretation indicates that 1 lithologic boundaries such as basement cover contacts although severely deformed during the alpine orogeny can be identified on the seismic sections 2 the top of the aar massif an external basement massif extends deep into the alpine orogen 3 the upper and lower parts of the crust are more or less transparent but are separated by a swarm of reflectors at mid crustal level 4 these mid crustal reflectors might be related to trapped fluids from alpine metamorphism and 5 the moho appears as a bright reflection that steepens from the north toward the south and terminates abruptly near the center of the alpine chain perhaps because of alpine deformation

evaluation of sulfur dioxide emissions from explosive volcanism the 1982 1983 eruptions of galunggung java indonesia abstract galunggung volcano java awoke from a 63 year quiescence in april 1982 and erupted sporadically through january 1983 during its most violent period from april to october the cikasasah volcano observatory reported 32 large and 56 moderate to small eruptions from april 5 through september 19 the total ozone mapping spectrometer toms carried on nasa s nimbus 7 satellite detected and measured 24 different sulfur dioxide clouds an estimated 1730 kilotons kt of so2 were outgassed by these explosive eruptions the trajectories and rapid dispersion rates of the so2 clouds were consistent with injection altitudes below the tropopause an additional 300 kt of so2 were estimated to have come from 64 smaller explosive eruptions based on the detection limit of the toms instrument for the first time an extended period of volcanic activity was monitored by remote sensing techniques which enabled observations of both the entire so2 clouds produced by large explosive eruptions using toms and the relatively lower levels of so2 emissions during non explosive outgassing using the correlation spectrometer or cospec based on cospec measurements from august 1982 to january 1983 and on the relationship between explosive and non explosive degassing approximately 400 kt of so2 were emitted during non explosive activity the total sulfur dioxide outgassed from galunggung volcano from april 1982 to january 1983 is calculated to be 2500 kt 30 from both explosive and non explosive activity while galunggung added large quantities of sulfur dioxide to the atmosphere its sporadic emissions occurred in relatively small events distributed over several months and reached relatively low altitudes and are unlikely to have significantly affected aerosol loading of the stratosphere in 1982 by volcanic activity

a crustal scale cross section of the south western alps combining geophysical and geological imagery a geotransect across the south western alps from the pelvoux massif external french alps to the dora maira massif internal italian alps through the monviso ophiolitic complex was investigated in the framework of the geo france 3d alpes programme a new interpretative crustal scale section across the south western alps is proposed combining geological and geophysical 2d 3d data the apulian mantle i e the ivrea body might be divided into two rigid pieces separated by the downward prolongation of the penninic frontal thrust these mantle indenters drive the decoupling of the european crust beneath the high to ultra high pressure metamorphic nappes the deep structure results from the stacking of crustal slices extracted from the european lithosphere the proposed struc tural model provides a basis for discussing the evidence of the crustal scale partitioning of the current strain pattern as well as the location of the seismicity

observation of so2 degassing at stromboli volcano using a hyperspectral thermal infrared imager abstract thermal infrared tir imaging is a common tool for the monitoring of volcanic activity broadband cameras with increasing sampling frequency give great insight into the physical processes taking place during effusive and explosive event while fourier transform infrared ftir methods provide high resolution spectral information used to assess the composition of volcanic gases but are often limited to a single point of interest continuing developments in detector technology have given rise to a new class of hyperspectral imagers combining the advantages of both approaches in this work we present the results of our observations of volcanic activity at stromboli volcano with a ground based imager the telops hyper cam lw when used to detect emissions of sulfur dioxide so2 produced at the vent with data acquired at stromboli volcano italy in early october of 2015 we have developed an innovative technique based on a curve fitting algorithm to quickly extract spectral information from high resolution datasets allowing fast and reliable identification of so2 we show in particular that weak so2 emissions such as inter eruptive gas puffing can be easily detected using this technology even with poor weather conditions during acquisition e g high relative humidity presence of fog and or ash then artificially reducing the spectral resolution of the instrument we recreated a variety of commonly used multispectral configurations to examine the efficiency of four qualitative so2 indicators based on simple brightness temperature difference btd our results show that quickly changing conditions at the vent including but not limited to the presence of summit fog render the establishment of meaningful thresholds for btd indicators difficult building on those results we propose recommendations on the use of multispectral imaging for so2 monitoring and routine measurements from ground based instruments

a comparison of so 2 retrieval techniques using mini uv spectrometers and aster imagery at lascar volcano chile the advanced spaceborne thermal emission and reflection radiometer aster is a useful tool for detecting low quantities of sulfur dioxide at passively degassing volcanoes such as lascar volcano chile two mini uv spectrometers muses were used to make transects of lascar volcano s sulfur dioxide plume on december 7 2004 during a coordinated overpass of aster so2 burdens were retrieved using the thermal infrared channels of the acquired aster image this allowed for a direct comparison between the two methods in order to validate the aster so2 retrieval the results were extremely encouraging with aster deriving so2 fluxes within the range of fluxes obtained by the muse

rheology and strength of the lithosphere abstract mechanical properties of lithosphere are of primary importance for interpretation of deformation at all spatial and time scales from local scale to large scale geodynamics and from seismic time scale to billions of years depending on loading conditions and time scale lithosphere exhibits elastic brittle plastic or viscous ductile properties as can be inferred from rock mechanics data a large part of the long term lithospheric strength is supported in the ductile or ductile elastic regime while it also maintains important brittle strength yet at short seismic time scale s the entire lithosphere responds in elastic brittle elastic regime even though rock mechanics experiments provide important insights into the rheological properties of the lithosphere their conditions e g time scales strain rates temperature and loading conditions are too far from those of real earth therefore these data cannot be reliably extended to geological time and spatial scales strain rates 10 17 to 10 13 s 1 without additional parameterization or validation based on geological time scale observations of large scale deformation for the oceanic lithosphere the goetze and evan s brittle elastic ductile yield strength envelopes yses were validated by geodynamic scale observations such as the observations of plate flexure however oceanic lithosphere behavior in subduction zones and passive continental margins is strongly conditioned by the properties of the continental counterpart whose rheology is less well understood for continents and continental margins the uncertainties of available data sources are greater due to the complex structure and history of continental plates for example in a common continental rheology model dubbed jelly sandwich the strength mainly resides in crust and mantle while in some alternative models the mantle is weak and the strength is limited to the upper crust we address the problems related to lithosphere rheology and mechanics by first reviewing the rock mechanics data te flexure and ts earthquake data and long term observations such as folding and subsidence data and then by examining the physical plausibility of various rheological models for the latter we review the results of thermo mechanical numerical experiments aimed at testing the possible tectonic implications of different rheology models in particular it appears that irrespective of the actual crustal strength the models implying weak mantle are unable to explain either the persistence of mountain ranges for long periods of time or the integrity of the subducting slabs although there is certainly no single rheology model for continents the jelly sandwich is a useful first order model with which to parameterize the long term strength of the lithosphere it is concluded that dry olivine rheology laws seem to represent well the long term behavior of mantle lithosphere in oceans margins and continents as to the continent and margin crust rheology analysis of the results of thermo mechanical models and of te data based on the most robust variants of flexural models suggests that continental plates with te 30 50 smaller than their theoretical mechanical thickness hm i e te 20 60 km should be characterized by a weak lower or intermediate crustal rheology enabling mechanical decoupling between crust and mantle older plates such as cratons are strong due to crust mantle coupling and specific properties of the cratonic mantle lithosphere

synthesizing multi sensor multi satellite multi decadal datasets for global volcano monitoring abstract owing to practical limitations less than half of earth s 1400 subaerial volcanoes have no ground monitoring and few are monitored consistently earth observing satellite missions provide global and frequent measurements of volcanic activity that are closing these gaps in coverage we compare databases of global satellite detections of ground deformation 1992 2016 so2 emissions 1978 2016 and thermal features 2000 2016 that together include 306 volcanoes each database has limitations in terms of spatial and temporal resolution but each technique contributed 45 86 unique detections of activity that were not detected by other techniques integration of these three databases shows that satellites detected 102 volcanic activities per year before the year 2000 and 103 activities per year after the year 2000 we find that most of the 54 erupting volcanoes without satellite detections are associated with low volcano explosivity index eruptions and note that many of these eruptions 71 97 135 occurred in the earliest decades of remote sensing pre 2000 when detection thresholds were high from 1978 to 2016 we conduct a preliminary analysis of the timing between the onset of satellite detections of deformation n 154 episodes n 71 volcanoes thermal features n 16 544 episodes n 99 volcanoes and so2 emissions n 1495 episodes n 116 volcanoes to eruption start dates we analyze these data in two ways first including all satellite detected volcanic activities associated with an eruption and second by considering only the first satellite detected activity related to eruption in both scenarios we find that deformation is dominantly pre eruptive 47 and 57 whereas available databases of thermal features and so2 emissions utilizing mainly low resolution sensors are dominantly co eruptive 88 and 76 for thermal features 97 and 96 for so2 emissions

mechanisms of continental subduction and exhumation of hp and uhp rocks abstract we discuss possible scenarios of continental collision and their relation to mechanisms of exhumation of hp and uhp rocks inferred from thermo mechanical numerical models accounting for thermo rheological complexity of the continental lithosphere due to this complexity mechanisms of continental convergence are versatile and different in many aspects from those that control oceanic subduction elucidating these mechanisms from conventional observations is difficult and requires additional constraints such as those derived from petrological data indeed exhumation of hp uhp rocks is an integral part of convergent processes and burial exhumation dynamics inferred from metamorphic p t t paths provides strong constraints on the collision scenarios metamorphic rocks also play an active role due to their contrasting physical properties rheology density fluid transport capacity numerical thermo mechanical experiments suggest that hp uhp exhumation can only be produced in subduction contexts as well as that long lasting 10 myr continental subduction can only occur in case of cold strong lithospheres t moho t e 50 km and of relatively high convergence rates 3 5 cm yr 1 in this case high density uhp material in the crustal part of subduction interface provides additional pull on the slab and is not always exhumed to the surface in case of slower convergence and or weaker lithosphere t e 1 is generally sufficient to drive continental subduction during the first several myr of convergence but pertinent subduction requires faster convergence rates 3 5 cm yr 1 we suggest that most continental orogenic belts could have started their formation from continental subduction but this process has been generally limited in time

continental lithosphere folding in central asia part ii constraints from gravity and topography abstract periodical sub parallel fold like structures observed in the western gobi have two characteristic dominant wavelengths of approximately 50 and 300 360 km we explain these observations in terms of independent quasi viscous folding of the crustal and upper mantle parts of the lithosphere due to horizontal transpressional stresses in central asia induced by the collision with the indian plate we derive a model for the mechanical response of the continental lithosphere to horizontal stresses for a rheologically layered plate with non newtonian power law rheology overlying a low viscosity asthenosphere the differentiation in the effective viscosity and thickness of the strong upper crust and upper mantle lithosphere along with the presence of a low viscosity lower crust between them leads to their partial decoupling during compressional deformation these features result in the appearance of different wavelengths of the folds in the western gobi region we derive simple semi analytical estimates for the dominant wavelengths and rates of growth of surface undulations constrained by data from experimental rock mechanics topography and gravity

mechanical characterization of limestone from sound velocity measurement the aim of this research was to establish correlations between different physical properties sound velocity vp bulk density and open porosity p0 and mechanical properties compressive strength rc tensile strength rt static elasticity modulus e0 and poisson s ratio i i of limestones the first step of the work consisted in an experimental campaign on limestone cores drilled from a gothic building in paris eight cores were extracted from the monument and tested in the laboratory secondly the experimental results were added to those proposed by 14 authors in the international scientific literature and all of these data were analyzed using the generalized least squares method so that correlation curves could be suggested seven correlations are proposed rc vp rc vp p0 e0 rc i i vp rt rc finally the dispersion of the results led to an estimated confidence level of 90 according to statistical considerations highlights we carried out an experimental physical and mechanical campaign on limestones cores correlations between different physical and mechanical properties are established dispersion of results led to an estimated confidence level according to statistical considerations

retrieval and intercomparison of volcanic so2 injection height and eruption time from satellite maps and ground based observations abstract syneruptive gas flux time series can in principle be retrieved from satellite maps of so 2 collected during and immediately after volcanic eruptions and used to gain insights into the volcanic processes which drive the volcanic activity determination of the age and height of volcanic plumes are key prerequisites for such calculations however these parameters are challenging to constrain using satellite based techniques here we use imagery from omi and gome 2 satellite sensors and a novel numerical procedure based on back trajectory analysis to calculate plume height as a function of position at the satellite measurement time together with plume injection height and time at a volcanic vent location we applied this new procedure to three etna eruptions 12 august 2011 18 march 2012 and 12 april 2013 and compared our results with independent satellite and ground based estimations we also compare our injection height time series with measurements of volcanic tremor which reflects the eruption intensity showing a good match between these two datasets our results are a milestone in progressing towards reliable determination of gas flux data from satellite derived so 2 maps during volcanic eruptions which would be of great value for operational management of explosive eruptions

thermal deformation and degassing remote sensing time series ce 2000 2017 at the 47 most active volcanoes in latin america implications for volcanic systems

multi decadal satellite measurements of global volcanic degassing abstract satellite instruments have been providing measurements of global volcanic emissions of sulfur dioxide so 2 since 1978 based on observations in the ultraviolet uv infrared ir and microwave spectral bands we review recent advances in satellite remote sensing of volcanic gases focusing on increased instrument sensitivity to tropospheric so 2 emissions and techniques to determine volcanic plume altitude a synthesis of 36 years of global uv ir and microwave satellite measurements yields an updated assessment of the volcanic so 2 flux to the upper troposphere and lower stratosphere utls between 1978 and 2014 1 2 tg yr the present availability of multiple uv and ir satellite so 2 products provides increased confidence in calculated so 2 loadings for many eruptions we examine the temporal and latitudinal distribution of volcanic so 2 emissions and reassess the relationship between eruptive so 2 discharge and eruption magnitude finding a first order correlation between so 2 emission and volcanic explosivity index vei but with significant scatter based on the observed so 2 vei relation we estimate the fraction of eruptive so 2 emissions released by the smallest eruptions 0 48 tg yr which is not recorded by satellite observations a detailed breakdown of the sources of measured so 2 emissions reveals intuitively expected correlations between eruption frequency so 2 loading and volcanic degassing style we discuss new constraints on e folding times for so 2 removal in volcanic plumes and highlight recent measurements of volcanic hydrogen chloride hcl injections into the utls an analysis of passive volcanic emissions of so 2 detected in ozone monitoring instrument omi so 2 data since 2004 provides new insight into the location and stability of the dominant sources of volcanic so 2 over the past decade since volcanic so 2 emissions constitute a random highly variable perturbation to the atmosphere climate system continued monitoring of volcanic so 2 emissions from space by multiple uv and ir instruments to extend the current multi decadal record is essential and near global geostationary measurements of so 2 may be available by the end of the current decade

neogene to ongoing normal faulting in the inner western alps a major evolution of the late alpine tectonics 1 widespread brittle extension occurs in the internal zones of the southwestern alps forming a dense fault network which overprints the compressional structures the extension has been followed by transcurrent motions in terms of paleostress this extension is radial to the belt close to the crustal penninic front and multidirectional in the eastern part of the internal zones the paleostress field of the strike slip phase is coherent with the extensional one and compatible with dextral shear along longitudinal faults globally we propose that the internal zones of the southwestern alps underwent a single neogene transtensive tectonic regime to strengthen our structural results the current tectonics has been analyzed using seismotectonic tools this approach allowed the recognition of several active faults moreover the ongoing tectonics is coherent with the observed brittle deformation the fault network controls the present day seismicity the combined seismotectonic and structural approaches give coherency and continuity from the neogene to ongoing extensional tectonics in the southwestern alps in the framework of the whole western alps a synthesis of our results with neotectonic related data allowed us to provide an accurate map of the neogene to present kinematics of the belt extension which appears as a major feature of the internal zones has been coeval with the propagation of thrusts in the outer zones during neogene times the geodynamic processes which rule this major tectonic evolution of the belt remain a matter of debate

modvolc near real time thermal monitoring of global volcanism modvolc is a non interactive algorithm developed at the hawaii institute of geophysics and planetology higp that uses low spatial resolution 1 km pixel size infrared satellite data acquired by the moderate resolution imaging spectroradiometer modis to map the global distribution of volcanic thermal anomalies in near real time modvolc scans the level 1b modis data stream on a pixel by pixel basis for evidence of pixel and sub pixel sized high temperature radiators once a hot spot has been identified its details location emitted spectral radiance time satellite observation geometry are written to ascii text files and transferred via ftp to higp from where the results are disseminated via the internet http modis higp hawaii edu in this paper we review the underlying principles upon which the algorithm is based before presenting some of the results and data that have been obtained since its inception we show how modvolc reliably detects thermal anomalies at a large number of persistently and sporadically active volcanoes that encompass the full range of common eruptive styles including erebus antarctica colima mexico karymsky kamchatka popocatepetl mexico etna italy and nyiragongo democratic republic of congo amongst others we also present a few cautionary notes regarding the limitations of the algorithm and interpretation of the data it provides

sangay volcano ecuador structural development present activity and petrology abstract sangay 5230 m the southernmost active volcano of the andean northern volcanic zone nvz sits 130 km above a 32 ma old slab close to a major tear that separates two distinct subducting oceanic crusts southwards quaternary volcanism is absent along a 1600 km long segment of the andes three successive edifices of decreasing volume have formed the sangay volcanic complex during the last 500 ka two former cones sangay i and ii have been largely destroyed by sector collapses that resulted in large debris avalanches that flowed out upon the amazon plain sangay iii being constructed within the last avalanche amphitheater has been active at least since 14 ka bp only the largest eruptions with unusually high plinian columns are likely to represent a major hazard for the inhabited areas located 30 to 100 km west of the volcano however given the volcano s relief and unbuttressed eastern side a future collapse must be considered that would seriously affect an area of present day colonization in the amazon plain 30 km east of the summit andesites greatly predominate at sangay there being few dacites and basalts in order to explain the unusual characteristics of the sangay suite highest content of incompatible elements except y and hree of any nvz suite low y and hree values in the andesites and dacites and high nb la of the only basalt found a preliminary five step model is proposed 1 an enriched mantle in comparison with an morb source or maybe a variably enriched mantle at the site of the sangay prior to quaternary volcanism 2 metasomatism of this mantle by important volumes of slab derived fluids enriched in soluble incompatible elements due to the subduction of major oceanic fracture zones 3 partial melting of this metasomatized mantle and generation of primitive basaltic melts with nb la values typical of the nvz which are parental to the entire sangay suite but apparently never reach the surface and subordinate production of high nb la basaltic melts maybe by lower degrees of melting at the periphery of the main site of magma formation that only infrequently reach the surface 4 afc processes at the base of a 50 km thick crust where parental melts pond and fractionate while assimilating remelts of similar basaltic material previously underplated producing andesites with low y and hree contents due to garnet stability at this depth 5 low pressure fractionation and mixing processes higher in the crust both an enriched mantle under sangay prior to volcanism and an important slab derived input of fluids enriched in soluble incompatible elements two parameters certainly related to the unique setting of the volcano at the southern termination of the nvz apparently account for the exceptionally high contents of incompatible elements of the sangay suite in addition the low cr ni values of the entire suite another unique characteristic of the nvz also requires unusual fractionation processes involving cr spinel and or clinopyroxene either in the upper mantle or at the base of the crust

present day vertical isostatic readjustment of the western alps revealed by numerical modelling and geodetic and seismotectonic data the active tectonics of the western alps reveals contrasting regimes ongoing extension at the heart of the chain and transpression compression at its external sectors the active processes currently affecting this region are still a matter of debate the classical models proposed in the literature invoke eurasia adria plate collision counterclockwise motion of the adria micro plate slab retreat of the subducted continental lithosphere and slab detachment more recently several authors prefer the hypothesis of tectonics driven by isostasy buoyancy forces to better understand the influence of these processes on the velocity strain and stress fields at the surface and in the crust we developed 2d viscoelastic numerical models along a vertical cross section perpendicular to the western alps we run our models with different driving forces in order to investigate one by one the geodynamic processes proposed in the literature results are compared with available geodetic geological and seismotectonic data in order to bring into coincidence model predictions and observations an important vertical isostatic readjustment must be included in the modelling together with a slight horizontal compression 0 5 mm year 1 probably due to africa eurasia convergence we show that the subduction process in this alpine region is likely to be dead and that buoyancy forces may be dominating the present day tectonics the geological society of london 2010

a simple inversion method for determining optimal dispersion model parameters from satellite detections of volcanic sulfur dioxide a simple inversion scheme for optimizing volcanic emission dispersion model parameters with respect to satellite detections is presented in this paper in this scheme multiple dispersion model simulations obtained by varying relevant model parameters are created and compared against satellite detections using pattern correlation as a measure of model agreement with observations it is shown that the scheme is successful in inferring emission source parameters such as those describing the vertical extent of the nascent sulfur dioxide emissions in the november 2010 mount merapi eruption in java indonesia these optimal parameter values then become a basis for improved forecasts of the transport of volcanic emissions

new lava lake at nyamuragira volcano revealed by combined aster and omi so2 measurements we report recent satellite measurements of the so2 emissions from the virunga volcanic group vvg which comprises the very active nyamuragira and nyiragongo volcanoes combining high time resolution data from the uv operating omi ozone monitoring instrument with high ground resolution data from the ir operating aster advanced spaceborne thermal emission and reflection radiometer we show that 1 the so2 emissions from the vvg have increased severalfold since the end of the last eruption of nyamuragira 2 nyamuragira which used to have very low intereruptive emissions of so2 before this eruption is now contributing to 60 to 90 of the combined emissions measured by omi considering the eruptive history of nyamuragira the evidence from previous research for the existence of a shallow magma chamber and the detection of isolated thermal anomalies since april 2014 we conclude that a deep seated lava lake has formed in the n pit of nyamuragira s caldera

characterization of a proposed palaeoproterozoic suture in the crust beneath the curnamona province australia abstract we use constrained forward and inverse modeling of bouguer gravity data to investigate a regional positive gravity anomaly that defines but is not confined to the eastern margin of the curnamona province best fit results imply that the positive gravity values are sourced from a relatively dense terrane 0 04 mg m 3 with respect to surrounding crust located at middle crustal levels 16 27 km depth which is likely dismembered and offset into discrete slivers by later tectonism consideration of pre 1500 ma plate reconstructions of the australian continent correlates this terrane with an interpreted buried suture in the mount isa inlier of northern australia where allochthonous crust was amalgamated to the australian margin at ca 2 20 1 85 ga bouguer gravity forward and inverse modeling also delineates a shallow west dipping crustal scale structure that possibly represents a primary boundary between precambrian basement of australia and the eastern fold belts accreted to the precambrian margin during the palaeozoic

daily monitoring of ecuadorian volcanic degassing from space we present daily measurements of sulfur dioxide so2 emissions from active volcanoes in ecuador and southern colombia between september 2004 and september 2006 derived from the ozone monitoring instrument omi on nasa s eos aura satellite omi is an ultraviolet visible spectrometer with an unprecedented combination of spatial and spectral resolution and global coverage that permits daily measurements of passive volcanic degassing from space we use non interactive processing methods to automatically extract daily so2 burdens and information on so2 sources from the omi datastream maps of monthly average so2 vertical columns retrieved by omi over ecuador and s colombia are also used to illustrate variations in regional so2 loading and to pinpoint sources the dense concentration of active volcanoes in ecuador provides a stringent test of omi s ability to distinguish so2 from multiple emitting sources our analysis reveals that tungurahua reventador and galeras were responsible for the bulk of the so2 emissions in the region in the timeframe of our study with no significant so2 discharge detected from sangay at galeras and reventador we conclude that omi can detect variations in so2 release related to cycles of conduit sealing and degassing which are a critical factor in hazard assessment the omi so2 data for reventador are the most extensive sequence of degassing measurements available for this remote volcano which dominated regional so2 production in june august 2005 at tungurahua the omi measurements span the waning stage of one eruptive cycle and the beginning of another and we observe increasing so2 burdens in the months prior to explosive eruptions of the volcano in july and august 2006 cumulative so2 loadings measured by omi yield a total of 1 16 tg so2 emitted by volcanoes on mainland ecuador s colombia between september 2004 and september 2006 as much as 95 of this so2 may originate from non eruptive degassing approximate apportionment of the total so2 loading indicates that 40 originated from tungurahua with 30 supplied by both reventador and galeras these measurements of volcanic so2 degassing in ecuador confirm omi s potential as an effective economical and risk free tool for daily monitoring of so2 emissions from hazardous volcanoes

how does micropetrography help us to understand the permeability and poromechanical behaviour of a rock many poromechanical studies of rocks give little regard to the micropetrographic observation of their constituents the aim of this study is to show how such a detailed study can help understand and provide more precision on the poromechanical behaviour of the material the rock studied here is an oolitic limestone micropetrography reveals the nature of the constituents calcite mostly in the form of fine grained micrite their abundance their organization micrite organized in ooids linked by a calcitic cement small sized highly connected isotropic porosity scarce unconnected porosity and the structure of the rock global isotropy small heterogeneities due to sedimentological phenomena no microcracks micropetrography completes the information obtained by poromechanics in that it allows the observation of elements deduced from macroscopical tests the aim of this paper is to show the effect of microporosity on permeability and flow in a rock where microporous grains are in contact with each other

a comparison of satellite and ground based measurements of so2 emissions from tungurahua volcano ecuador satellite measured so2 mass loadings and ground based measurements of so2 emission rate are not directly comparable with 40 differences between mean emissions reported by each technique from tungurahua volcano ecuador during late 2007 numerical simulations of postemission processing and dispersal of tungurahua s so2 emissions enable more effective comparison of ground and satellite based so2 data sets reducing the difference between them and constraining the impact of plume processing on satellite so2 observations ground based measurements of so2 emission rate are used as the model input and simulated so2 mass loadings are compared to those measured by the ozone monitoring instrument omi the changing extent of so2 processing has a significant impact on daily variation in so2 mass loading for a fixed volcanic emission rate however variations in emission rate at tungurahua are large suggesting that overall volcanic source strength and not subsequent processing is more likely to be the dominant control on atmospheric mass loading so2 emission rate estimates are derived directly from the omi observations using modeled so2 lifetime good agreement is achieved between both observed and simulated mass loadings 21 and satellite derived and ground measured so2 emission rates 18 with a factor of 2 improvement over the differences found by simple direct comparison while the balance of emission source strength and postemission processing will differ between volcanoes and regions under good observation conditions and where so2 lifetime is 24 hours satellite based sensors like omi may provide daily observations of so2 mass loading which are a good proxy for volcanic source strength

gravity modelling along the ecors crop vertical seismic reflection profile through the western alps abstract new gravity data from 500 stations and results from all previous surveys on the western alps are used to compile a detailed profile along the ecors crop vertical seismic profile the bouguer anomaly consists of two approximately two dimensional regional features namely a wide negative anomaly occurring on the central part of the belt and the pronounced positive anomaly of the geophysical ivrea zone at the border between the alps and the po plain the results of a wide angle seismic campaign and the preliminary line drawing from the vertical seismic have been the main constraints for the modelling of the anomaly two models are proposed their common feature is a piling up of the crust upper mantle units in the penninic zone of maximum crustal thickness as well as in the ivrea zone the contribution of the apulian lower crust to the positive anomaly is greater than formerly suggested several hypotheses are put forward for the zones where reasonable seismic information is available as an illustration of the uncertainties surrounding their geological interpretation the density models are consistent with the hypothesis of lithospheric accretionary processes for the collision between the european and apulian plates

rheological and geodynamic controls on the mechanisms of subduction and hp uhp exhumation of crustal rocks during continental collision insights from numerical models while subduction of crustal rocks is increasingly accepted as a common scenario inherent to convergent processes involving continental plates and micro continents its occurrence in each particular context as well as its specific mechanisms and conditions is still debated the presence of ultra high pressure uhp terranes is often interpreted as a strong evidence for continental subduction subduction of continental crust since the latter is seen as the most viable mechanism of their burial to uhp depths yet if one admits nearly lithostatic pressure conditions in the subduction interface or channel the presumed links of continental subduction to exhumation of high and ultra high pressure hp uhp units also remain a subject of controversy despite the fact that recent physically consistent thermo mechanical numerical models of convergent processes suggest that subduction can create specific mechanisms for uhp exhumation we hence review and explore possible scenarios of subduction of continental crust and their relation to exhumation of hp and uhp rocks as inferred from last generation of thermo mechanical numerical models accounting for thermo rheological complexity and structural diversity of the continental lithosphere the inferences from these models are matched with the petrology data in particular with p t t paths allowing for better understanding of subtleties of both subduction and burial exhumation mechanisms numerical models suggest that exhumation and continental subduction are widespread but usually transient processes that last for less than 5 10 myr while long lasting 10 15 myr subduction can take place only in rare cases of fast convergence of cold strong lithospheres e g india the models also show that tectonic heritage can play a special role in subduction exhumation processes in particular when thicker continental terrains are embedded in subducting oceanic plate exhumation of uhp terranes results in the formation of versatile metamorphic belts and domes and in series of slab roll back and exhumation events with remarkably different p t t records

thermo mechanical approach to validation of deep crustal and lithospheric structures inferred from multidisciplinary data application to the western and northern alps current multidisciplinary studies confront the difficult problem of validation and verification of internal compatibility of geophysical and geological data of different nature quality and origin our geodynamic approach exploits the natural interdependence between the data related to different physical properties of geological structures density rheology temperature stress using the latter as input for a thermo mechanical finite element model we can verify whether the inferred properties and geometries i are mechanically stable ii require rheologically consistent stresses strains realistic thermal conditions etc and 3 will evolve in a geologically realistic way in the future this mechanically balanced approach is tested on the alpine orogen ecors and nfp20 profiles in the framework of the geofrance 3d programme the results suggest a number of corrections and adjustments that can be made to existing seismically and gravity predicted geometries of structures such as the ivrea body and those of the depleted subducted crust

fumarole plume and diffuse co 2 emission from sierra negra caldera galapagos archipelago measurements of visible and diffuse gas emission were conducted in 2006 at the summit of sierra negra volcano galapagos with the aim to better characterize degassing after the 2005 eruption a total so2 emission of 11 2 t day 1 was derived from miniature differential optical absorption spectrometer mini doas ground based measurements of the plume emanating from the mini azufral fumarolic area the most important site of visible degassing at sierra negra volcano using a portable multigas system the h2s so2 co2 so2 and h2o so2 molar ratios in the mina azufral plume emissions were found to be 0 41 52 2 and 867 9 respectively the corresponding h2o co2 and h2s emission rates were 562 394 and 3 t day 1 respectively the total output of diffuse co2 emissions from the summit of sierra negra volcano was 990 85 t day 1 with 605 t day 1 being released by a deep source the diffuse to plume co2 emission ratio was about 1 5 mina azufral fumaroles released gasses containing 73 6 mol of h2o the main noncondensable components amounted to 97 4 mol co2 1 5 mol so2 0 6 mol h2s and 0 35 mol n2 the higher h2s so2 ratio values found in 2006 as compared to those reported before the 2005 eruption reveal a significant hydrothermal contribution to the fumarolic emissions 3he 4he ratios measured at mina azufral fumarolic discharges showed values of 17 88 0 25 ra indicating a mid ocean ridge basalts morb and a galapagos plume contribution of 53 and 47 respectively

a coupled hydro mechanical model for simulation of gas migration in host sedimentary rocks for nuclear waste repositories abstract in a deep geological repository dgr for nuclear wastes several mechanisms such as waste form degradation and corrosion could lead to gas generation the produced gas can potentially overpressurize the repository alter the hydraulic and mechanical properties of the host rock and affect the long term containment function of the natural host rock and engineered barriers thus the understanding of the gas migration within the host rock and engineered barriers and the associated potential impacts on their integrity is important for the safety assessment of a dgr in this paper a coupled hydro mechanical model for predicting and simulating the gas migration in sedimentary host rock is presented a detailed formulation coupling moisture liquid water and water vapor and gas transfer in a deformable porous medium is given the model takes into account the damage controlled fluid gas water flow as well as the coupling of hydraulic and mechanical processes e g stress deformation the model also considers the coupling of the diffusion coefficient with mechanical deformation as well as considers the modification of capillary pressure due to the variation of permeability and porosity the prediction capability of the developed model is tested against laboratory scale and in situ experiments conducted on potential host sedimentary rocks for nuclear waste disposal the model predictions are in good agreement with the experimental results the numerical simulations of the laboratory and field gas injection tests provide a better understanding of the mechanisms of gas migration and the potential effects of excessive gas pressure on the host sedimentary rocks this research work has allowed us to identify key features related to gas generation and migration that are considered important in the long term safety assessment of a dgr in sedimentary host formations

degassing patterns of tungurahua volcano ecuador during the 1999 2006 eruptive period inferred from remote spectroscopic measurements of so2 emissions this paper presents the results of 7 years aug 1999 oct 2006 of so2 gas measurements during the ongoing eruption of tungurahua volcano ecuador from 2004 onwards the operation of scanning spectrometers has furnished high temporal resolution measurements of so2 flux enabling this dataset to be correlated with other datasets including seismicity the emission rate of so2 during this period ranges from less than 100 to 35000 tonnes day t d with a mean daily emission rate of 1458 t d and a standard deviation of 2026 t d average daily emissions during inferred explosive phases are about 1 75 times greater than during passive degassing intervals the total amount of sulfur emitted since 1999 is estimated as at least 1 91 mt mostly injected into the troposphere and carried westwards from the volcano our observations suggest that the rate of passive degassing at tungurahua requires so2 exsolution of an andesitic magma volume that is two orders of magnitude larger than expected for the amount of erupted magma two possible and not mutually exclusive mechanisms are considered here to explain this excess degassing gas flow through a permeable stagnant magma filled conduit and gas escape from convective magma overturning in the conduit we have found that real time gas monitoring contributes significantly to better eruption forecasting at tungurahua because it has provided improved understanding of underlying physical mechanisms of magma ascent and eruption

in situ measurements of tropospheric volcanic plumes in ecuador and colombia during tc4 a nasa dc 8 research aircraft penetrated tropospheric gas and aerosol plumes sourced from active volcanoes in ecuador and colombia during the tropical composition cloud and climate coupling tc 4 mission in july august 2007 the likely source volcanoes were tungurahua ecuador and nevado del huila colombia the tc 4 data provide rare insight into the chemistry of volcanic plumes in the tropical troposphere and permit a comparison of so 2 column amounts measured by the ozone monitoring instrument omi on the aura satellite with in situ so 2 measurements elevated concentrations of so 2 sulfate aerosol and particles were measured by dc 8 instrumentation in volcanic outflow at altitudes of 3 6 km estimated plume ages range from 2 h at huila to 22 48 h downwind of ecuador the plumes contained sulfate rich accumulation mode particles that were variably neutralized and often highly acidic a significant fraction of supermicron volcanic ash was evident in one plume in plume o 3 concentrations were 70 80 of ambient levels downwind of ecuador but data are insufficient to ascribe this to o 3 depletion via reactive halogen chemistry the tc 4 data record rapid cloud processing of the huila volcanic plume involving aqueous phase oxidation of so 2 by h 2o 2 but overall the data suggest average in plume so 2 to sulfate conversion rates of 1 2 h 1 so 2 column amounts measured in the tungurahua plume 0 1 0 2 dobson units are commensurate with average so 2 columns retrieved from omi measurements in the volcanic outflow region in july 2007 the tc 4 data set provides further evidence of the impact of volcanic emissions on tropospheric acidity and oxidizing capacity

merapi 2010 eruption chronology and extrusion rates monitored with satellite radar and used in eruption forecasting abstract despite dense cloud cover satellite borne commercial synthetic aperture radar sar enabled frequent monitoring of merapi volcano s 2010 eruption near real time interpretation of images derived from the amplitude of the sar signals and timely delivery of these interpretations to those responsible for warnings allowed satellite remote sensing for the first time to play an equal role with in situ seismic geodetic and gas monitoring in guiding life saving decisions during a major volcanic crisis our remotely sensed data provide an observational chronology for the main phase of the 2010 eruption which lasted 12 days 26 october 7 november 2010 unlike the prolonged low rate and relatively low explosivity dome forming and collapse eruptions of recent decades at merapi the eruption began with an explosive eruption that produced a new summit crater on 26 october and was accompanied by an ash column and pyroclastic flows that extended 8 km down the flanks this initial explosive event was followed by smaller explosive eruptions on 29 october 1 november then by a period of rapid dome growth on 1 4 november which produced a summit lava dome with a volume of 5 10 6 m 3 a paroxysmal vei 4 magmatic eruption with ash column to 17 km altitude destroyed this dome greatly enlarged the new summit crater and produced extensive pyroclastic flows to 16 km radial distance in the gendol drainage and surges during the night of 4 5 november the paroxysmal eruption was followed by a period of jetting of gas and tephra and by a second short period 12 h of rapid dome growth on 6 november the eruption ended with low level ash and steam emissions that buried the 6 november dome with tephra and continued at low levels until seismicity decreased to background levels by about 23 november our near real time commercial sar documented the explosive events on 26 october and 4 5 november and high rates of dome growth 25 m 3 s 1 an event tree analysis for the previous 2006 merapi eruption indicated that for lava dome extrusion rates 1 2 m 3 s 1 the probability of a large 1872 scale eruption was 10 consequently the order of magnitude greater rates in 2010 along with the explosive start of the eruption on 26 october the large volume of lava accumulating at the summit by 4 november and the rapid and large increases in seismic energy release deformation and gas emissions were the basis for warnings of an unusually large eruption by the indonesian geological agency s center for volcanology and geologic hazard mitigation cvghm and their volcano research and technology development center bpptk in yogyakarta warnings that saved thousands of lives

rheology of the lithosphere selected topics we review recent results concerning the rheology of the lithosphere with special attention to the following topics 1 the flexure of the oceanic lithosphere 2 deformation of the continental lithosphere resulting from vertical surface loads and forces applied at plate margins 3 the rheological stratification of the continents 4 strain localization and shear zone development and 5 strain induced crystallographic preferred orientations and anisotropies in body wave velocities we conclude with a section citing the 1983 1986 rock mechanics literature by category

stratovolcano growth by co eruptive intrusion the 2008 eruption of tungurahua ecuador 1 volcanic edifices are constructed by a combination of erupted material and internal growth we use the l band satellite alos to produce insar measurements at tungurahua volcano ecuador we find a maximum of 17 5 cm of uplift on the upper western flank between december 2007 and march 2008 coincident with an eruption in february 2008 the deformation can be modeled using an ellipsoidal or sill like source within the edifice the models require an elongated aspect ratio with a length of 4 6 km the intruded volume of 1 2 106 m3 is roughly equivalent to the bulk erupted volume of 1 5 106 m3 and together the values are roughly equal to the long term magma flux the question remains whether this uplift is permanent thus contributing to the internal growth of the edifice or temporary in which case the magma will be released in a future eruption

evaluation of redoubt volcano s sulfur dioxide emissions by the ozone monitoring instrument abstract the 2009 eruption of redoubt volcano alaska provided a rare opportunity to compare satellite measurements of sulfur dioxide so2 by the ozone monitoring instrument omi with airborne so2 measurements by the alaska volcano observatory avo herein we 1 compare omi and airborne so2 column density values for redoubt s tropospheric plume 2 calculate daily so2 masses from mount redoubt for the first three months of the eruption 3 develop simple methods to convert daily measured so2 masses into emission rates to allow satellite data to be directly integrated with the airborne so2 emissions dataset 4 calculate cumulative so2 emissions from the eruption and 5 evaluate omi as a monitoring tool for high latitude degassing volcanoes a linear correlation r2 0 75 is observed between omi and airborne so2 column densities omi daily so2 masses for the sample period ranged from 60 1 kt on 24 march to below detection limit with an average daily so2 mass of 6 7 kt the highest so2 emissions were observed during the initial part of the explosive phase and the emissions exhibited an overall decreasing trend with time omi so2 emission rates were derived using three methods and compared to airborne measurements this comparison yields a linear correlation r2 0 82 with omi derived emission rates consistently lower than airborne measurements the comparison results suggest that omi s detection limit for high latitude springtime conditions varies from 2000 to 4000 t d cumulative so2 masses calculated from daily omi data for the sample period are estimated to range from 542 to 615 kt with approximately half of this so2 produced during the explosive phase of the eruption these cumulative masses are similar in magnitude to those estimated for the 1989 90 redoubt eruption strong correlations between daily omi so2 mass and both tephra mass and acoustic energy during the explosive phase of the eruption suggest that omi data may be used to infer relative eruption size and explosivity further when used in conjunction with complementary datasets omi daily so2 masses may be used to help distinguish explosive from effusive activity and identify changes in lava extrusion rates the results of this study suggest that omi is a useful volcano monitoring tool to complement airborne measurements capture explosive so2 emissions and provide high temporal resolution so2 emissions data that can be used with interdisciplinary datasets to illuminate volcanic processes

micromechanical modeling of the effective elastic properties of oolitic limestone a new micromechanical approach to analytical modeling of oolitic limestone is proposed limestone is modeled as a multiphase composite consisting of sparry calcite matrix spherical oolitic inhomogeneities oblate spheroidal pores of aspect ratio 0 2 and concave pores in the shape of superspheres the concavity factor is the key parameter affecting overall properties maxwell s homogenization scheme is used to calculate effective bulk and shear moduli of this multiphase composite as functions of total porosities the results are in good agreement with experimental data available in the literature

determination of the main hydraulic and poro elastic properties of a limestone from bourgogne france this study is a part of a large experimental program intended to characterise the effects of increasing temperature upon the hydraulic and poro mechanical behaviour of a limestone from anstrude france methods of measurement as well as experimental devices designed by our laboratory are presented and commented on permeability values measured on six different samples either with gas or ethanol clearly show that the results obtained with the two fluids are virtually identical as soon as the gas measurements are corrected for the klinkenberg effect as the permeability is not very sensitive to confining pressure variation it can be assumed that the intact rock is slightly cracked this is confirmed with microscopic observations as well as poro elastic property measurements concerning the latter various ways of obtaining their values are presented and compared they include drained and undrained bulk modulus biot and skempton coefficients and biot modulus the consistency between these parameters is finally highlighted and demonstrates that the classical theory of poro elasticity hold very well for such a rock which is almost monomineralic with quite a high porosity

lithospheric wedging in the western alps inferred from the ecors crop traverse the ecors crop traverse integrates vertical and wide angle seismic reflection gravity and magnetic studies along a 190 km profile across the western alps the combination of geophysical and geologic data constrains the deep structure along the traverse although alternative models are not excluded the model that best fits the data of crustal accretion implies that after the consumption of the piemontese ocean continental collision proceeded by lithospheric wedging of the subducting european continental foreland in the internal zones further shortening may have been achieved by an unknown amount of penetrative deformation and by back thrusting

pre eruptive physical conditions of el reventador volcano ecuador inferred from the petrology of the 2002 and 2004 05 eruptions abstract a petrological study of the eruptive products of el reventador allowed us to infer the magmatic processes related to the 2002 and 2004 05 eruptions of this andesitic stratovolcano on november 3 2002 el reventador experienced a highly explosive event which was followed by emplacement of two lava flows in november december 2002 silica contents range from 62 to 58 wt sio2 for the november 3 pyroclastic deposits to 58 56 and 54 53 wt sio2 for the successive lava flows in november 2004 eruptive activity resumed supplying four new lava flows 56 54 wt sio2 between november 2004 and august 2005 volatile contents in matrix glasses and glass inclusions from the november 3 pyroclastic deposits allow us to estimate the total amount of so2 and hcl released into the atmosphere during the paroxysmal phase i e 80 kt of so2 and 280 kt of hcl pre eruptive pressure temperature conditions of the magmas range from 300 to 150 mpa and 1000 c with high water contents 5 wt we propose the existence of an andesitic magma body located at 7 12 km depth that is frequently intruded by more primitive hydrous magmas from a deeper source the initial crystallization of amphibole from the hydrous primitive magma seems typical of el reventador as well as the historically recurrent and regular periods of eruptive activity lasting several years this eruptive behaviour coupled with the fractionation and mixing processes inferred from the 2002 and 2004 05 petrologic data suggest that deep magmatic recharge at el reventador is frequent and is probably responsible for the high frequency of eruptions

space and ground based measurements of sulphur dioxide emissions from turrialba volcano costa rica remotely sensed measurements of sulphur dioxide so2 emitted by turrialba volcano costa rica are reported for the period september 2009 january 2011 these measurements were obtained using images from advanced spaceborne thermal emission and reflexion radiometer ozone monitoring instrument and a ground based uv camera these three very different instruments provide flux measurements in good agreement with each other which demonstrate that they can be integrated for monitoring so2 fluxes fluxes from turrialba increased fourfold in january 2010 following a phreatic explosion that formed a degassing vent in the w crater of turrialba since then the so2 flux has remained high 30 50 kg s but seems to be showing a slowly decreasing trend we interpret this evolution as the start of open vent degassing from a recently intruded magma body the opening of the degassing vent decreased the confining pressure of the magma body and allowed the gases to bypass the hydrothermal system

a model of vulcanian eruptions at galeras volcano colombia abstract a series of six vulcanian eruptions at galeras volcano colombia occurred during 1992 1993 these eruptions followed the emplacement of a lava dome in late 1991 which was accompanied by cooling crystallizing and partial solidification of the column of magma plugging the conduit five of the eruptions were preceded by episodes of monochromatic long period seismicity suggesting cyclic pressurization of the magma the quiescent intervals between eruptions generally decreased with each successive eruption we propose a model of gas release from magma into confined stationary pore spaces by 5 10 crystallization of anhydrous minerals causing repeated overpressurization of the magmatic system using initial lithostatic pressures of 20 100 mpa 800 3900 m depth gas buildup by crystallization indicates overpressures of 3 17 mpa which is the approximate fracture criterion for a magma chamber our galeras data suggest two models of pressurization 1 gas exsolution may have occurred at similar depths but with progressively smaller overpressures being developed before each successive eruption according to this model the comparatively long quiescent periods between the first eruptions resulted in relatively large amounts of gas exsolution from the magma and accumulation in pore spaces whereas the shorter quiescent periods for the later eruptions exsolved less gas the decrease in overpressure with time may have resulted from progressive fracturing of partly solidified magma during the eruptions which progressively decreased the tensile strength and increased the permeability of the magma 2 since overpressures are smaller at shallower depths for a given amount of crystallization the first eruptions of 1992 1993 were caused by gas exsolution at shallow depths while the last eruptions having shorter quiescent intervals resulted from a greater amount of gas exsolution at greater depths in this case the rate of gas exsolution varied as a function of depth the two scenarios for pressurization may be combined into a more general model involving edifice weakening and the development of a shallow hydrothermal system from continued degassing of the magma plug as weakening of the edifice formed an extensive system of fractures the shallow hydrothermal system deepened due to meteoric water input and magmatic degassing with time a greater number of fractures were filled and partly sealed by hydrothermal minerals at progressively deeper levels as a result the source of the overpressure also deepened with time

ice cap melting and low viscosity crustal root explain the narrow geodetic uplift of the western alps more than 10 years of geodetic measurements demonstrate an uplift rate of 1 3 mm yr of the high topography region of the western alps by contrast no significant horizontal motion has been detected two uplift mechanisms have been proposed 1 the isostatic response to denudation responsible for only a fraction of the observed uplift and 2 the rebound induced by the wurmian ice cap melting which predicts a broader uplifting region than the one evidenced by geodetic observations using a numerical model to fit the geodetic data we show that a crustal viscosity contrast between the foreland and the central part of the alps the latter being weaker with a viscosity of 1021 pa s is needed the vertical rates are enhanced if the strong uppermost mantle beneath the moho is interrupted across the alps therefore allowing a weak vertical rheological anomaly over the entire lithosphere

correlations between so2 flux and long period seismicity at galeras volcano the 14 january 1993 eruption of galeras volcano in colombia which killed six scientists and three tourists1 was followed by a larger eruption on 23 march 19932 both eruptions were preceded by episodes of long period seismicity the source of long period seismic events has been modelled extensively3 8 as the resonance within a fluid filled crack induced by pressure transients in the fluid5 7 here we use the so2 flux from galeras volcano measured remotely to infer the degassing history during the episode of long period events preceding the 23 march eruption so2 flux and long period seismicity have been monitored separately elsewhere to forecast volcanic activity9 13 our results show how the combination and correlation of the two methods can be used to interpret the movement of gases from the magma body to the surface and to monitor the pressure buildup leading to an eruption at explosive volcanoes

mapping the moho of the western alps by wide angle reflection seismics abstract a new picture of the moho beneath the western alps could be obtained using wide angle reflection seismic data this picture in addition to its increased sharpness clearly shows how the moho deepens down to the root zone of the chain 55 km a 25 30 km deep reflector with upper mantle characteristics is discovered under the brianconnais zone where it overlies the autochthonous moho this unit does not seem to connect to the so called ivrea body situated much shallower and farther into the chain it supports a hypothetical flaking of the european lithosphere beneath the western alps farther east the moho beneath the po plain is clearly mapped too with a crustal thickness increasing in steps from 25 to 35 km this p wave moho picture is compared with an s wave picture and major differences appearing in the middle crust are discussed finally the seismic response of the moho is investigated and is shown to be shifted towards low frequencies in the inner zones of the chain this could partly explain why the ecors crop vertical seismic line equipped with high frequency geophones faltered over the identification of the deep alpine moho

volcano monitoring applications of the ozone monitoring instrument the ozone monitoring instrument omi is a satellite based ultraviolet uv spectrometer with unprecedented sensitivity to atmospheric sulphur dioxide so2 concentrations since late 2004 omi has provided a high quality so2 dataset with near continuous daily global coverage in this review we discuss the principal applications of this dataset to volcano monitoring 1 the detection and tracking of large eruption clouds primarily for aviation hazard mitigation and 2 the use of omi data for long term monitoring of volcanic degassing this latter application is relatively novel and despite showing some promise requires further study into a number of key uncertainties we discuss these uncertainties and illustrate their potential impact on volcano monitoring with omi through four new case studies we also discuss potential future avenues of research using omi data with a particular emphasis on the need for greater integration between various monitoring strategies instruments and datasets

a model of degassing at galeras volcano colombia 1988 1993 galeras volcano reactivated in early 1988 as evidenced by increased seismicity gas emissions and fumarole temperatures and had a series of explosive eruptions in may 1989 during 1989 1990 the volcano was characterized by high so 2 flux reaching 5000 t metric tons day this period of strong degassing was followed by upward movement of magma july september 1991 and the emplacement of a lava dome october november 1991 since november 1991 long period seismicity and so 2 flux have decreased indicating that the conduit has partially sealed itself probably by crystallization and solidification of the magma on july 16 1992 the dome was destroyed by an explosion consistent with pressurization due to sealing and degassing in a nonporous medium continued pressurization beneath the volcano is indicated by eruptions on january 14 march 23 april 4 april 13 and june 7 1993 glass inclusion and matrix glass analyses support a hypothesis of significant magma degassing at depth in the magma chamber and in the conduit this degassing has reduced the h 2 o s and cl contents of the magma but the f content appears to have increased due to crystallization of anhydrous mineral phases and to the low fluid melt partition coefficient for f despite its degassed state galeras is currently a dangerous volcano because the sealing process forces gas saturated magma to release volatile components into confined spaces thereby causing pressurization and explosive eruptions

a thermomechanical model of exhumation of high pressure hp and ultra high pressure uhp metamorphic rocks in alpine type collision belts using a fully coupled numerical thermomechanical model handling strain localization surface processes and ultra high viscosity contrasts 11 orders of magnitude we test a number of possible mechanisms of high pressure hp low temperature lt high temperature ht exhumation in continental collision zones the model considers two end member cases low or high buoyancy of the downgoing crust the first model case predicts three levels of exhumation in the same collisional context the classical corner flow lp lt low pressure low temperature exhumation in the accretionary prism deeper 70 km hp ht exhumation for the thickened subducting crustal sedimentary wedge and ultra hp ht exhumation from the lower crustal chamber forming at the depth of 100 120 km and separated from the upper one by a narrow crustal channel the width of this channel can oscillate in the process of shortening thus controlling the quantity of the crustal material exchanged between the crustal wedge and the lower crustal chamber although both zones of crustal accumulation and the narrow channel between them resemble a vortex shaped nozzle this nozzle appears to be too soft to produce any significant overpressures from the upper crustal wedge the material is exhumed following the ascending shear flow created by the overriding plate assisted by positive buoyancy of the heated crustal material from the lower crustal chamber the material is transported upward to the upper crustal wedge by a flow induced by the asthenospheric traction and a small scale convective instability forming in the lower crustal chamber due to its heating by the overriding asthenosphere in the second modelled case of high buoyancy the latter mechanisms become dominant resulting in hyper fast exhumation of the crust to the surface accelerated or slowed subduction in case of full or partial crustal decoupling respectively and upper plate extension d 2001 elsevier science b v all rights reserved

estimating rates of decompression from textures of erupted ash particles produced by 1999 2006 eruptions of tungurahua volcano ecuador persistent low to moderate level eruptive activity of andesitic volcanoes is difficult to monitor because small changes in magma supply rates may cause abrupt transitions in eruptive style as direct measurement of magma supply is not possible robust techniques for indirect measurements must be developed here we demonstrate that crystal textures of ash particles from 1999 to 2006 vulcanian and strombolian eruptions of tungurahua volcano ecuador provide quantitative information about the dynamics of magma ascent and eruption that is difficult to obtain from other monitoring approaches we show that the crystallinity of erupted ash particles is controlled by the magma supply rate msr ash erupted during periods of high magma supply is substantially less crystalline than during periods of low magma supply this correlation is most easily explained by efficient degassing at very low pressures 50 mpa and degassing driven crystallization controlled by the time available prior to eruption our data also suggest that the observed transition from intermittent vulcanian explosions at low msr to more continuous periods of strombolian eruptions and lava fountains at high msr can be explained by the rise of bubbles through strombolian or trapping of bubbles beneath vulcanian vent capping variably viscous and crystalline magma

infrasound from tungurahua volcano 2006 2008 strombolian to plinian eruptive activity abstract strombolian to plinian activity from tungurahua volcano ecuador has been recorded by the autonomous infrasound arrays of the acoustic surveillance for hazardous eruptions ashe project since early 2006 our studies suggest that acoustic energy release during large eruptions does appear to broadly scale with eruption intensity this manuscript provides a detailed chronology and characterization of tungurahua s eruptive activity between 2006 and 2008 and demonstrates the ability to constrain source parameters of significant eruptions such as onset duration and escalation at regional distances by combining infrasound and remote sensing techniques the ashe system in ecuador automatically detected over 20 000 volcanic explosions at an array 37 km from tungurahua and was successful at notifying the onset escalation and cessation of a hazardous february 2008 eruption with a latency of 5 min elevated infrasonic energy from sustained and intense tungurahua eruptions correlates well with ash column heights and their lateral extent during the study period the spectra of these sustained explosive eruptions appear to be recurrent readily recognizable and indicative of volcanic jetting and significant atmospheric ash injection the paroxysmal plinian phase of the august 2006 eruption produced an ash cloud that extended well into the stratosphere 24 km coinciding with a shift of the dominant jetting frequency from 0 25 hz to below 0 1 hz and radiation of over 5 107 w of acoustic power transient explosions were often marked by minor or no ash release and are presumed to be more gas rich a change in the acoustic spectrum of volcanic jetting was also detected in the transition from a sustained to collapsed eruption column at the end of the july 14 2006 eruption the jetting spectrum at tungurahua during a period of sustained pyroclastic density current production changes from a typical double peaked to a single peaked spectrum suggesting remote acoustic monitoring can help ascertain the stability and dynamics of an eruptive column

first estimate of volcanic so2 budget for vanuatu island arc abstract the spatial and temporal coverage of measurements of volcanic gas emissions remains patchy however over the last decade emissions inventories have improved thanks to new measurements of some of the lesser known volcanic areas we report on one such region the vanuatu island arc in the southwest pacific for which we now have sufficient systematic observations to offer a systematic emissions inventory our new estimate is based on so 2 flux measurements made in the period 2004 2009 with ultraviolet spectroscopy techniques for the following volcanoes yasur lopevi ambrym ambae gaua and vanua lava from south to north these are the first ever measurements for lopevi gaua and vanua lava the results reveal the vanuatu arc as one of earth s prominent sources of volcanic degassing with a characteristic annual emission to the atmosphere of 3 tg of so 2 representing about 20 of hitherto published global estimates our new dataset highlights the sustained prodigious degassing of ambrym volcano whose 5 gg day 1 mean flux of so 2 represents nearly two thirds of the total budget for the vanuatu arc this confirms ambrym as one of the largest volcanic sources worldwide comparable to etna often considered as the most vigorous source of volcanic emission on earth we also report a high degassing for ambae of 2 gg day 1 so 2 representing more than 28 of the vanuatu arc budget thus 90 of the so 2 output from vanuatu is focused in the central part of the arc from ambrym and ambae where magmas originate from enriched indian type mantle and where peculiar tectonic conditions could favor high magma production rates

in situ stress state in the linxing region eastern ordos basin china implications for unconventional gas exploration and production abstract the carboniferous and permian sedimentary rocks mainly the shanxi and taiyuan formations in the linxing region eastern ordos basin china host a significant volume of unconventional gas resources coalbed methane shale gas and tight sandstone gas currently the in situ stress state is poorly understood but knowledge of this is extremely important for a range of applications such as gas exploration and production fracture stimulation and wellbore stability the maximum horizontal stress s hmax minimum horizontal stress s hmin and vertical stress s v magnitudes and the s hmax orientation in the linxing region were systematically analyzed for the first time in the present study which can provide a reference for subsequent numerical simulation and hydraulic fracturing design based on borehole breakouts and drilling induced tensile fractures interpreted from borehole imaging logs the s hmax orientation rotates from nee sww trending in the southern part to nww see trending in the northern part of the linxing region both conventional logs and extended leak off tests were used for stress magnitude determination the results revealed three types of in situ stress fields s v s hmax s hmin s hmax s v s hmin and s hmax s v s hmin and a dominant strike slip stress regime s hmax s v s hmin was found for the entire well section in the target shanxi formation and taiyuan formation in the linxing region in addition differential stress increased with depth in the linxing region which indicates that wellbore instability might be a potentially significant problem when drilling wells that are vertical or n s trending

measuring volcanic degassing of so2 in the lower troposphere with aster band ratios we present a new method for measuring so2 with the data from the aster advanced spaceborne thermal emission and reflectance radiometer orbital sensor the method consists of adjusting the so2 column amount until the ratios of radiance simulated on several aster bands match the observations we present a sensitivity analysis for this method and two case studies the sensitivity analysis shows that the selected band ratios depend much less on atmospheric humidity sulfate aerosols surface altitude and emissivity than the raw radiances measurements with 25 relative precision are achieved but only when the thermal contrast between the plume and the underlying surface is higher than 10 k for the case studies we focused on miyakejima and etna two volcanoes where so2 is measured regularly by cospec or scanning doas the so2 fluxes computed from a series of ten images of miyakejima over the period 2000 2002 is in agreement with the long term trend of measurement for this volcano on etna we compared so2 column amounts measured by aster with those acquired simultaneously by ground based automated scanning doas the column amounts compare quite well providing a more rigorous validation of the method the so2 maps retrieved with aster can provide quantitative insights into the 2d structure of non eruptive volcanic plumes their dispersion and their progressive depletion in so2

poor scaling between elastic energy release and eruption intensity at tungurahua volcano ecuador 1 an important objective in volcanology is the quantification of eruption intensity through the study of elastic energy propagated into the atmosphere and ground to better understand the relation between elastic wave radiation and eruptive activity we deployed seismic acoustic and video instrumentation at the active tungurahua volcano ecuador in nov dec of 2004 our data show that plume expansion scales very poorly with both seismic and acoustic trace energy and only the initial amplitude of the acoustic signal is perhaps correlated with initial plume rise speeds in general the eventual size of tungurahua eruption plumes does not appear to be controlled by elevated material accelerations within the conduit which are primary influences on elastic energy radiation this result has vital implications for volcano observatories which are interested in using seismic and acoustic trace amplitudes as proxies for eruption magnitudes

thermorheological model for the european central alps brittle ductile transition and lithospheric strength a two dimensional thermorheological model of the central alps along a north south transect is presented thermophysical and rheological parameters of the various lithological units are chosen from seismic and gravity information the inferred temperature distribution matches surface heat flow and results in moho temperatures between 500 and 800 c both european and adriatic lithospheres have a jelly sandwich structure with a 15 20 km thick brittle upper crust overlying a ductile lower crust and a mantle lid whose uppermost part is brittle the total strength of the lithosphere is of the order of 0 5 1 0 1013 n m 1 if the upper mantle is dry or slightly less if the upper mantle is wet in both cases the higher values correspond to the adriatic indenter

ten years of satellite observations reveal highly variable sulphur dioxide emissions at anatahan volcano mariana islands satellite remote sensing enables continuous multiyear observations of volcanic activity in remote settings anatahan mariana islands is a remote volcano in the western north pacific available ground based measurements of sulphur dioxide so2 gas emissions at anatahan place it among thelargest volcanic so2 sources worldwide these ground based measurements however are restricted to eruptive intervals anatahan s activity since 2003 has been dominated temporally by prolonged periods of quiescence using 10 years of satellite observations from omi airs sciamachy and gome 2 we report highly variable so2 emissions within and between eruptive and quiescent intervals at anatahan we find close correspondence between levels of activity reported at the volcano and levels of so2 emissions detected from space eruptive so2 emission rates have a mean value of 6400 t d 1 but frequently are in excess of 20 000 t d 1 conversely so2 emissions during quiescent intervals are below the detection limit of space based sensors and therefore are not likely to exceed 300 t d 1 we show that while anatahan occupies a quiescent state for 85 of the past 10 years only 15 of total so2 emissions over this interval occur during quiescence with the remaining 85 released in short duration but intense syn eruptive degassing we propose that the integration of multiyear satellite data sets and activity histories are a powerful complement to targeted ground based campaign measurements in better describing the long term degassing behavior of remote volcanoes

theoretical prediction of poroelastic properties of argillaceous rocks from in situ specific storage coefficient 1 an integrated and theoretical approach is proposed to determine poroelastic properties of isotropic or transversely isotropic argillaceous rocks from conventional mechanical and hydraulic field tests it uses values of specific storage coefficient undrained elastic parameters and porosity no special hydromechanical test is required in the isotropic case a simple binomial equation is derived whereby the poroelastic properties can be rapidly obtained an application to deep argillaceous formations has shown that calculated poroelastic property values are in satisfactory agreement with direct experimental measurements in the transversely isotropic case which is more representative of sedimentary rocks the approach is generalized from a theoretical relationship between the specific storage coefficient and the anisotropic poroelastic properties nevertheless in both cases sensitivity analyses have shown that the method is very sensitive to input data especially the specific storage coefficient and the undrained mechanical parameters which have to be measured with accuracy

pyroclastic flow erosion and bulking processes comparing field based vs modeling results at tungurahua volcano ecuador pyroclastic density currents pdcs are high temperature and high velocity mixtures that threaten populations in the vicinity of many active volcanoes deciphering the cause of their remarkable mobility is essential for volcanic hazard analysis but remains difficult because of the complex processes occurring within the flows here we investigate the effect of bulking on dense pdc mobility by means of a double approach first we estimate the amount of material incorporated into scoria flows emplaced during the august 2006 eruption of tungurahua volcano ecuador for this we carry out a detailed analysis of 3d corrected digital images of well exposed scoria flow deposits componentry analysis indicates that pdc bulking occurs principally on the steep 25 upper slope of the volcano and the deposits typically comprise 40 50 wt of non juvenile i e accessory and accidental material secondly we develop a simple stress related grain by grain equation of erosion combined with two simple depth averaged geophysical mass flow models that compare the bulking mechanism to a non fluidized and a fluidized flow two behaviors based on coulomb and plastic rheologies are used to reproduce on a first order basis the 2006 tungurahua pdcs cross check comparisons between these modeled cases and the erosion pattern inferred from field based data allow us to evaluate the accuracy of our modeling assumptions regardless of the rheological regime the pdc induced erosion pattern of the 2006 tungurahua eruption can only be reproduced by fluctuations of the flow s basal shear stress during emplacement such variations are controlled by flow thinning thickening processes notably through the formation of a thick non erosive flow body that pushes a thin frictional erosive front during pdc emplacement the input volume of juvenile material as well as the thickness of the erodible layer available prior to the eruption are additional key parameters our work highlights complexities in pdc erosion and bulking processes that deserve further study in terms of hazard assessment our findings reveal that incorporation and bulking translate into increased flow mobility i e the augmented flow mass enhances both flow velocity and runout distance up to 20 these outcomes should be considered closely for hazard analysis at many other andesitic volcanoes worldwide where similar pdc events are common

deep structure of the alps what do we really know abstract in the last five decades the deep structure of the alps has been probed by every geophysical method applicable and the resulting amount of data is unmatched for any other orogen in this study an attempt is made to review the data and the proposed structural models with the aim of separating the certain from the probable and from the speculative information this can be achieved by first reviewing the theoretical resolving power and ambiguity of the applied interpretation methods and then analysing the proposed models the methods reviewed are inversion of surface wave data teleseismic and local earthquake seismic tomography near vertical reflection seismology wide angle reflection and refraction seismology and gravity modelling all information about the moho rated as certain is combined to give a moho map of the alpine area the information rated as certain and probable and additional qualitative arguments are used to discuss a crustal model of the western and central alps represented by two cross sections major structural elements in this crustal model are a thick overthrust penninic nappe system wedging at mid to lower crustal levels a discontinuous moho and strong variations along the strike of the orogen whereas the structures of the european upper crust and of the penninic nappe system are well constrained only few and isolated lower crustal structural elements are rated as certain finally the shape of the lower lithosphere in the alps is discussed by review and comparison of the results from surface wave teleseismic travel time residual and tomographic studies qualitative arguments suggest the existence of a lithospheric root or slab beneath the alps probable tomographic information suggests a south vergent european lithospheric slab beneath the southern alps and the po plain despite the considerable number of studies aimed at resolving the deepest part of alpine orogeny the available quantitative information on the sub moho structure cannot be rated as certain

first synoptic analysis of volcanic degassing in papua new guinea we report the first satellite based survey of volcanic sulphur dioxide so2 degassing in papua new guinea using ozone monitoring instrument omi data omi is sensitive to low level passive degassing these observations are useful for volcano monitoring hazard assessment particularly aviation hazard and assessment of arc geochemical budgets and are of immense value in remote regions with little ground based instrumentation such as papua new guinea we identify bagana manam rabaul ulawun and langila as the active sources of volcanic so2 in papua new guinea with bagana being the largest source we present an omi so2 time series for 2005 2008 and a total detected regional output of 1 8 109 kg so2 about 40 of emissions were released by major eruption events at manam january 2005 bagana june 2006 and rabaul october 2006 over the past century however we estimate that major explosive eruptions contribute 5 of the arc scale so2 emission budget ground based doas measurements of so2 degassing at five of papua new guinea s volcanoes are compared with our omi observations the total omi so2 output is only 20 of the total extrapolated from doas a discrepancy which we demonstrate is consistent with other volcanic arcs therefore the true total regional so2 output may be considerably higher than that detected by omi uncertainties in the omi so2 data include the effects of in plume chemical processing and dilution of so2 prior to the satellite overpass omi s reduced sensitivity to low levels of so2 in the planetary boundary layer and interference by meteorological clouds

present day stress and pore pressure fields in the cuu long and nam con son basins offshore vietnam abstract knowledge of the in situ or contemporary stress field is vital for planning optimum orientations of deviated and horizontal wells reservoir characterization and a better understanding of geodynamic processes and their effects on basin evolution this study provides the first documented analysis of in situ stress and pore pressure fields in the sedimentary formations of the cuu long and nam con son basins offshore vietnam based on data from petroleum exploration and production wells in the cuu long basin the maximum horizontal stress is mainly oriented in nnw sse to n s in the northern part and central high in the nam con son basin the maximum horizontal stress is mainly oriented in ne sw in the northern part and to n s in the central part of the basin the magnitude of the vertical stress has a gradient of approximately 22 2 mpa km at 3500 m depth minimum horizontal stress magnitude is approximately 61 of the vertical stress magnitude in normally pressured sequences the effect of pore pressure change on horizontal stress magnitudes was estimated from pore pressure and fracture tests data in depleted zone caused by fluid production and an average pore pressure stress coupling ratio s h p p obtained was 0 66 the minimum horizontal stress magnitude approaches the vertical stress magnitude in overpressured zones of the nam con son basin suggesting that an isotropic or strike slip faulting stress regime may exist in the deeper overpressured sequences