preliminary sensitivity study of eruption source parameters for operational volcanic ash cloud transport and dispersion models a case study of the august 1992 eruption of the crater peak vent mount spurr alaska abstract ash clouds are one of the major hazards that result from volcanic eruptions once an eruption is reported volcanic ash transport and dispersion vatd models are used to forecast the location of the ash cloud these models require source parameters to describe the ash column for initialization these parameters include eruption cloud height and vertical distribution particle size distribution and start and end time of the eruption further if downwind concentrations are needed the eruption mass rate and or volume of ash need to be known upon notification of an eruption few constraints are typically available on many of these source parameters recently scientists have defined classes of eruption types each with a set of pre defined eruption source parameters esp we analyze the august 18 1992 eruption of the crater peak vent at mount spurr alaska which is the example case for the medium silicic eruption type we have evaluated the sensitivity of two of the esp the grain size distribution gsd and the vertical distribution of ash on the modeled ash cloud hysplit and puff vatd models are used to simulate the ash clouds from the different sets of source parameters we use satellite data processed through the reverse absorption method as reference for computing statistics that describe the modeled to observed comparison with the grain size distribution the three options chosen 1 an estimated distribution based on past eruption studies 2 a distribution with finer particles and 3 the national oceanic and atmospheric administration hysplit gsd have little effect on the modeled ash cloud for the initial vertical distribution both linear uniform concentration throughout the vertical column and umbrella shapes were chosen for hysplit the defined umbrella distribution no ash below the umbrella apparently underestimates the lower altitude portions of the ash cloud and as a result has a worse agreement with the satellite detected ash cloud compared to that with the linear vertical distribution for this particular eruption the puff model with a poisson function to represent the umbrella cloud gave similar results as for a linear distribution both having reasonable agreement with the satellite detected cloud further sensitivity studies of this eruption as well as studies using the other source parameters are needed

synthetic signatures of volcanic ash cloud particles from x band dual polarization radar weather radar retrieval in terms of detection estimation and sensitivity of volcanic ash plumes is dependent not only on the radar system specifications but also on the range and ash cloud distribution the minimum detectable signal can be increased for a given radar and ash plume scenario by decreasing the observation range and increasing the operational frequency and also by exploiting possible polarimetric capabilities for short range observations in proximity of the volcano vent a compact portable system with relatively low power transmitter may be evaluated as a suitable compromise between observational and technological requirements this paper starting from the results of a previous study and from the aforementioned issues is aimed at quantitatively assessing the optimal choices for a portable x band system with a dual polarization capability for real time ash cloud remote sensing the physical electromagnetic model of ash particle distributions is systematically reviewed and extended to include nonspherical particle shapes vesicular composition silicate content and orientation phenomena the radar backscattering response at x band is simulated and analyzed in terms of self consistent polarimetric signatures for ash classification purposes and correlation with ash concentration for quantitative retrieval aims an x band radar system sensitivity analysis to ash concentration as a function of radar specifications range and ash category is carried out in trying to assess the expected system performances and limitations

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

observations of volcanic clouds in their first few days of atmospheric residence the 1992 eruptions of crater peak mount spurr volcano alaska abstract satellite so2 and ash measurements of mount spurr s three 1992 volcanic clouds are compared with ground based observations to develop an understanding of the physical and chemical evolution of volcanic clouds each of the three eruptions with ratings of volcanic explosivity index three reached the lower stratosphere 14 km asl but the clouds were mainly dispersed at the tropopause by moderate to strong 20 40 m s tropospheric winds three stages of cloud evolution were identified first heavy fallout of large 500 m pyroclasts occurred close to the volcano 25 km from the vent during and immediately after the eruptions and the cloud resembled an advected gravity current second a much larger highly elongated region marked by a secondary mass maximum occurred 150 350 km downwind in at least two of the three events this was the result of aggregate fallout of a bimodal size distribution including fine 25 m ash that quickly depleted the solid fraction of the volcanic cloud for the f

estimating volcanic ash hazard in european airspace abstract the widespread disruption of european air traffic in late april 2010 during the eruption of eyjafjallajokull showed the importance of early assessment of volcanic hazard from explosive eruptions in this study we focus on the short term hazard of airborne ash from a climatological perspective focusing on eruptions on iceland by studying eruptions of different intensity and frequency we estimate the overall probability that ash concentration levels considered hazardous to aviation are exceeded over different parts of europe the method involves setting up a range of eruption scenarios based on the eruptive history of icelandic volcanoes and repeated simulation of these scenarios for 2 years worth of meteorological data simulations are conducted using meteorological data from the era interim reanalysis set which is downscaled using the weather research and forecasting wrf model the weather data are then used to drive the lagrangian particle dispersion model flexpart wrf for each of the eruption scenarios a set of threshold values commonly used in volcanic ash advisories are used to analyze concentration data from the dispersion model we see that the dispersion of ash is highly dominated by the mid latitude westerlies and mainly affect northern uk and the scandinavian peninsula the occurrence of high ash levels from icelandic volcanoes is lower over continental europe but should not be neglected for eruptions when the release rate of fine ash m is in the order of 10 7 kg s 1 or higher there is a clear seasonal variation in the ash hazard during the summer months the dominating dispersion direction is less distinct with some plumes extending to the northwest and greenland in contrast during the winter months the strong westerly winds tend to transport most of the emissions eastwards the affected area of a winter time eruption is likely to be larger as high concentrations can be found at a further distance downwind from the volcano effectively increasing the probability of hazardous levels of ash reaching the european continent the concentration thresholds for aviation which were adopted after the eyjafjallajokull eruption in 2010 have strong influence on the hazard estimates for weaker eruptions but is less important for larger eruptions thus ash forecasts for weaker eruptions are likely more uncertain in comparison to larger eruptions

hydrometeor enhanced tephra sedimentation constraints from the 18 may 1980 eruption of mount st helens 1 uncertainty remains on the origin of distal mass deposition maxima observed in many recent tephra fall deposits in this study the link between ash aggregation and the formation of distal mass deposition maxima is investigated through reanalysis of tephra fallout from the mount st helens 18 may 1980 msh80 eruption in addition we collate all the data needed to model distal ash sedimentation from the msh80 eruption cloud four particle size subpopulations were present in distal fallout with modes at 2 2 4 2 5 9 and 8 3 settling rates of the coarsest subpopulation closely matched predicted single particle terminal fall velocities sedimentation of particles 100 m was greatly enhanced predominantly through aggregation of a particle subpopulation with modal diameter 5 9 0 2 19 3 m mammatus on the msh80 cloud provided a mechanism to transport very fine ash particles with predicted atmospheric lifetimes of days to weeks from the upper troposphere to the surface in a matter of hours in this mechanism ash particles initiate ice hydrometeor formation high in the troposphere subsequently the volcanic cloud rapidly subsides as mammatus develop from increased particle loading and cloud base sublimation rapid fallout occurs as the cloud passes through the melting level in a process analogous to snowflake aggregation aggregates sediment en masse and form the distal mass deposition maxima observed in many recent volcanic ash fall deposits this work provides a data resource that will facilitate tephra sedimentation modeling and allow model intercomparisons

rock magnetic properties of the fine grained sediment on the outer shelf of the east china sea implication for provenance the rock magnetic properties of surface sediments from the fine grained depositional area on the outer shelf of the east china sea an area surrounded by sands were investigated with a view to providing information on the sediment provenance multiple magnetic parameters such as magnetic susceptibility anhysteretic remanent magnetization saturation remanent magnetization sirm coercivities of sirm and s ratios relative abundance of low coercivity magnetic minerals were measured for all 179 surface samples and partial representative samples were examined for their magnetic hysteresis parameters temperature dependence of magnetic susceptibility and x ray diffraction spectra our research indicates that the magnetic mineralogy is dominated by magnetite with a small amount of hematite and is primarily of a pseudo single domain to multidomain nature with a detrital origin the magnetic concentration in the study area generally decreases to the east or southeast accompanied by magnetic particle fining to the east or northeast the geographic pattern of magnetic properties is most reasonably explained by a major source of sediment jointly from the erosion of the old huanghe river deposit and the discharge of the changjiang river the rock magnetic data facilitate understanding of the transport mechanism of fine grained sediments in the outer shelf of the east china sea

volcanic ash hazard climatology for an eruption of hekla volcano iceland abstract ash produced by a volcanic eruption on iceland can be hazardous for both the transatlantic flight paths and european airports and airspace in order to begin to quantify the risk to aircraft this study explored the probability of ash from a short explosive eruption of hekla volcano 63 98 n 19 7 w reaching european airspace transport dispersion and deposition of the ash cloud from a three hour explosive eruption with an initial plume height of 12 km was simulated using the met office s numerical atmospheric dispersion modelling environment name the model used operationally by the london volcanic ash advisory centre eruptions were simulated over a six year period from 2003 until 2008 and ash clouds were tracked for four days following each eruption results showed that a rapid spread of volcanic ash is possible with all countries in europe facing the possibility of an airborne ash concentration exceeding international civil aviation organization icao limits within 24 h of an eruption an additional high impact low probability event which could occur is the southward spread of the ash cloud which would block transatlantic flights approaching and leaving europe probabilities of significant concentrations of ash are highest to the east of iceland with probabilities exceeding 20 in most countries north of 50 n deposition probabilities were highest at scottish and scandinavian airports there is some seasonal variability in the probabilities ash is more likely to reach southern europe in winter when the mean winds across the continent are northerly ash concentrations usually remain higher for longer during summer when the mean wind speeds are lower

a study on the development of subsidence due to the extraction of 1203 slice with its associated factors around barapukuria underground coal mining industrial area dinajpur bangladesh subsidence as a result of an underground coal mine is a hazard to human life properties and environment this incidence usually occurs over a long period of time which directly or indirectly pertinent with various factors that needs to be carefully considered and systematically analyzed when exploring land subsidence in reality the relationships among factors their effects and the subsidence are crucial to have the suitable management plan for the mine induced ground subsidence around the mining area in this research primarily the development of subsidence caused by the extraction of 1203 slice has been evaluated under the profile functions and influence functions methods the results show that the calculated subsidence profile is almost trough like subsidence where the maximum amount of subsidence is about 0 89 m secondly based on this result the analysis on different factors such as the deeper coal bed 420 m depth level and higher angle of draw 42 5o show less subsidence which are 0 58 and 0 87 m respectively whereas the dip of the coal bed up to 20o does not have significant effect on subsidence in latter cases the different preceding scientific papers have been consulted and analyzed for recognizing various influencing factors of subsidence which replicate that the geology and stratigraphic configuration structural setting of the coal basin hydro geological characteristics less competent nature of overlying rock body applied mining method presence of multi coal seams ultra thicken coal seam and so on are the major factors in affecting the subsidence event in the area moreover intensive site investigations revealed similar pattern of subsidence and its associated factors around the mine

fusion characteristics of volcanic ash relevant to aviation hazards the fusion dynamics of volcanic ash strongly impacts deposition in hot parts of jet engines in this study we investigate the sintering behavior of volcanic ash using natural ash of intermediate composition erupted in 2012 at santiaguito volcano guatemala a material science procedure was followed in which we monitored the geometrical evolution of cylindrical shaped volcanic ash compact upon heating from 50 to 1400 c in a heating microscope combined morphological mineralogical and rheological analyses helped define the evolution of volcanic ash during fusion and sintering and constrain their sticking potential as well as their ability to flow at characteristic temperatures for the ash investigated 1240 c marks the onset of adhesion and flowability the much higher fusibility of ash compared to that of typical test sands demonstrates for the need of a more extensive fusion characterization of volcanic ash in order to mitigate the risk posed on jet engine operation

a multidisciplinary effort to assign realistic source parameters to models of volcanic ash cloud transport and dispersion during eruptions during volcanic eruptions volcanic ash transport and dispersion models vatds are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind those models use input parameters called eruption source parameters such as plume height h mass eruption rate duration d and the mass fraction m63 of erupted debris finer than about 4 or 63 m which can remain in the cloud for many hours or days observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected moreover observed plume height may change during an eruption requiring rapid assignment of new parameters this paper reports on a group effort to improve the accuracy of source parameters used by vatds in the early hours of an eruption we do so by first compiling a list of eruptions for which these parameters are well constrained and then using these data to review and update previously studied parameter relationships we find that the existing scatter in plots of h versus yields an uncertainty within the 50 confidence interval of plus or minus a factor of four in eruption rate for a given plume height this scatter is not clearly attributable to biases in measurement techniques or to well recognized processes such as elutriation from pyroclastic flows sparse data on total grain size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions 0 01 and large silicic ones 0 5 we classify eleven eruption types four types each for different sizes of silicic and mafic eruptions submarine eruptions brief or vulcanian eruptions and eruptions that generate co ignimbrite or co pyroclastic flow plumes for each eruption type we assign source parameters we then assign a characteristic eruption type to each of the world s 1500 holocene volcanoes these eruption types and associated parameters can be used for ash cloud modeling in the event of an eruption when no observational constraints on these parameters are available

increasing magnetic susceptibility of the suspended particles in yangtze river and possible contribution of fly ash abstract the magnetic properties of soil have been increasingly applied as a rapid and economic way to monitor environment pollution sediments from a growing islet in the lower reach of yangtze river as well as the suspended particles in the surrounding river water were used to identify anthropogenic influence on the magnetic susceptibility ms of the yangtze river sediment results show that newly deposited sediments in 2004 have significantly higher ms 150 10 8 m3 kg 1 on average than that of the ancient deposit 50 10 8 m3 kg 1 scanning electron microscope sem of the extracted magnetic particles from newly deposited sediments and fly ash samples indicates large contribution of fly ash for the samples with elevated ms dependence of ms on grain size is evident which enable calculation of the ms of suspended particles from river sediment a value of 32 10 8 m3 kg 1is inferred for the suspended particles in ancient yangtze river the records from 2004 to 2010 indicate progressive increase in the ms of the suspended particles in yangtze river from 67 to 96 10 8 m3 kg 1 which is much higher than that of the ancient mass balance calculation based on the increasing ms suggests that at least 7 of the fly ash produced within the catchment of yangtze river was released into the environment

the 2005 eruption of kliuchevskoi volcano chronology and processes derived from aster spaceborne and field based data abstract kliuchevskoi volcano located on the kamchatka peninsula of eastern russia is one of the largest and most active volcanoes in the world its location and diversity of eruption styles make satellite based monitoring and characterization of its eruptive activity essential in 2005 the kamchatka volcano emergency response team kvert first reported that seismic activity of kliuchevskoi increased above background levels on 12 january kamchatka volcanic eruption response team kvert report 2005 kliuchevskoi volcano 14 january through 13 may 2005 http www avo alaska edu activity avoreport php view kam info id month january year 2005 cited january 2007 by 15 january kliuchevskoi entered an explosive effusive phase which lasted for five months and produced basaltic lava flows lahar deposits and phreatic explosions along its northwestern flank we present a comparison between field observations and multispectral satellite image data acquired by the advanced spaceborne thermal emission and reflection radiometer aster instrument in order to characterize the eruptive behavior the aster instrument was targeted in an automated urgent request mode throughout the eruption timeline in order to collect data at the highest observation frequency possible brightness temperatures were calculated in all three aster wavelength regions during lava flow emplacement the maximum lava flow brightness temperatures calculated from the 15 m pixel visible near infrared vnir data were in excess of 800 c the shortwave infrared swir data were radiometrically and geometrically corrected normalized to the same gain settings and used to estimate an eruptive volume of 2 35 10 2 km 3 at the summit these data were also used to better constrain errors arising in the thermal infrared tir data due to sub pixel thermal heterogeneities based on all the aster data the eruption was separated into three phases an initial explosive phase 20 january 31 january an explosive effusive phase 1 february 8 march and a subsequent cooling phase decorrelation stretch dcs images of the tir data also suggested the presence of silicate ash so 2 and water vapor plumes that extended up to 300 km from the summit the aster rapid response program provided important multispectral moderate spatial resolution information that was used to detect and monitor the eruptive activity of this remote volcano which can be applied to other eruptions worldwide

three dimensional time varying large surface displacements in coal exploiting areas revealed through integration of sar pixel offset measurements and mining subsidence model abstract underground mining activities usually induce large surface displacements thus causing serious safety hazards and potential ecological damage the capability of conventional interferometric synthetic aperture radar insar to monitor tectonic movements volcanic eruptions and city subsidence has been fully demonstrated but its application to mining subsidence is limited because of the failure caused by localized surface displacements with strong spatial gradients in this paper a new method is presented to utilize sar pixel offset tracking ot with a single pair of sar images to resolve three dimensional 3d large surface displacements caused by underground coal mining coal mining subsidence theory is utilised to analytically separate the vertical and horizontal components this method is applied to the daliuta coal mining area in shaanxi province china where a dense gps network is available results show the rms differences of ot derived displacements against gps in both horizontal and vertical directions are in the sub centimeter level in addition a prediction of mining induced ground movements is performed with the support vector regression algorithm and rms differences of 12 4 13 1 and 14 4 cm are observed compared to gps in the vertical easting and northing directions respectively the framework demonstrated in this paper is not only able to derive the evolution of the 3d large surface displacements with multi temporal sar images in a single geometry but also has a potential for short term predication which can provide early warnings and promote strategic decision making for engineering management in the process of coal mining

the influences of mining subsidence on the ecological environment and public infrastructure a case study at the haolaigou iron ore mine in baotou china the scope and extent of mine subsidence caused by exploitation of metal ores are usually low however in some cases owing to such factors as special geological conditions in ore body backward mining technology and unsound management systems exploitation of metal ores would also lead to a large area of mine subsidence causing great damages to the mining environment and infrastructure a serious mine subsidence happened in january 2007 at the haolaigou iron ore mine has caused a huge collapse pit on the earth s surfaces this provides a suitable place to study the influence of mine subsidence based on former research results a 3d geological model is constructed using the rock model software developed by authors group based on in situ geological conditions the range of orebody mining and the physical and mechanical parameters of rock and soil mass were determined by inverse analysis creep analysis of the collapse pit was also performed furthermore the elastoplastic and creep of the secondary collapse were computed and the final range of the collapse pit was predicted finally the influences of mining subsidence on the ecological environment and public infrastructure are discussed and control measures were proposed the results indicate that the collapse pit would not affect the road even if creep is considered however the secondary collapse would influence the road so the collapse pit should be dealt with as soon as possible

researches on detection of 3 d underground cave based on tem technique because of unreasonable coal mining in china there are many unknown underground caves and the inhabited environment of humans is threatened by many geologic hazards such as cracking of the buildings ground subsidence etc to make the coal companies aware of the harmfulness of these hazards it is urgent to determine the reasons for the hazards in this paper transient electromagnetic method tem is used to detect the ground resistance caves instead of the time consuming and expensive direct drilling survey numerical results of the 3 d synthetic model and real field survey data are given the results showed that the tem method can be used to detect a complicated air filled underground 3 d cave and coincide with the results of direct drilling survey

a review of tephra transport and dispersal models evolution current status and future perspectives abstract tephra transport models try to predict atmospheric dispersion and sedimentation of tephra depending on meteorology particle properties and eruption characteristics defined by eruption column height mass eruption rate and vertical distribution of mass models are used for different purposes from operational forecast of volcanic ash clouds to hazard assessment of tephra dispersion and fallout the size of the erupted particles a key parameter controlling the dynamics of particle sedimentation in the atmosphere varies within a wide range largest centimetric to millimetric particles fallout at proximal to medial distances from the volcano and sediment by gravitational settling on the other extreme smallest micrometric to sub micrometric particles can be transported at continental or even at global scales and are affected by other deposition and aggregation mechanisms different scientific communities had traditionally modeled the dispersion of these two end members volcanologists developed families of models suitable for lapilli and coarse ash and aimed at computing fallout deposits and for hazard assessment in contrast meteorologists and atmospheric scientists have traditionally used other atmospheric transport models dealing with finer particles for tracking motion of volcanic ash clouds and eventually for computing airborne ash concentrations during the last decade the increasing demand for model accuracy and forecast reliability has pushed on two fronts first the original gap between these different families of models has been filled with the emergence of multi scale and multi purpose models second new modeling strategies including for example ensemble and probabilistic forecast or model data assimilation are being investigated for future implementation in models and or modeling strategies this paper reviews the evolution of tephra transport and dispersal models during the last two decades presents the status and limitations of the current modeling strategies and discusses some emergent perspectives expected to be implemented at operational level during the next few years improvements in both real time forecasting and long term hazard assessment are necessary to loss prevention programs on a local regional national and international level

integrated satellite observations of the 2001 eruption of mt cleveland alaska abstract satellite data were the primary source of information for the eruption of mt cleveland alaska on 19 february and 11 and 19 march 2001 multiple data sets were used pre syn and post eruption to mitigate the hazard and determine an eruption chronology the 19 february eruption was the largest of the three resulting in a volcanic cloud that formed an arc over 1000 km long moved to the ne across alaska and was tracked using satellite data over more than a 50 h period the volcanic cloud was concurrently detected on the goes avhrr and modis data at various times and their respective signals compared all three sensors detected a cloud that had a very similar shape and position but there were differences in their areal extent and internal structural detail goes data showed the largest volcanic cloud in terms of area probably due to its oblique geometry modis bands 31 and 32 which are comparable to goes and avhrr thermal infrared wavelengths were the least effective single channels at detecting the volcanic cloud of those investigated modis bands 28 29 31 and 32 modis bands 28 and 29 detected the largest volcanic clouds that could easily be distinguished from weather clouds of the split window data modis bands 29 minus band 32 detected the largest cloud but the band 31 minus band 32 data showed the volcanic cloud with the most internal structural detail the puff tracking model accurately tracked the movement and predicted the extent and shape of this complex cloud even into areas beyond satellite detection numerous thermal anomalies were also observed during the eruption on the twice daily avhrr data and the high spatial resolution landsat data the high resolution radarsat data showed that the avhrr thermal anomalies were due to lava and debris flow features and a newly formed fan along the west coast of the island field observations and images from a hand held forward looking infrared radiometer flir showed that the flow features were a a lava debris flows and a warm debris fan along the west coast real time satellite data were the primary tool used to monitor the eruption track changes and to mitigate hazards high resolution data even though coverage is infrequent were critical in helping to identify volcanic processes and to compile an eruption chronology

environmental magnetism as a dating proxy for recent overbank sediments of peri industrial regions in the czech republic and uk abstract twenty five floodplain sediment profiles from seven rivers in eastern czech republic and three in north west england were collected to examine the hypothesis that magnetic enhancement in recent sediments is predominantly of anthropogenic origin and that magnetic parameters can be used as a dating proxy reflecting changes in intensity of industry sources over time natural sources of magnetic enhancement were excluded and anthropogenic enhancement was identified as exhibiting elevated values of lf arm sirm sirm and s ratios with low values of fd magnetic spherules typically formed through fossil fuel combustion processes were observed by scanning electron microscopy sem in these sediments to assess the potential of magnetic parameters as a chronometer the approach was compared with frequently used dating techniques concentrations of heavy metals and 137 cs the floodplain profiles were divided to three groups according to the characteristics of their trends with depth in magnetic parameters lf in particular and the suitability of magnetic properties as a dating proxy group 1 which included the majority of the profiles exhibited magnetic enhancement in the upper part of its profiles and a single maximum in lf this group exhibited a clear suitability for our proposed magnetic dating as the magnetic record reflected the industrial history of the region and was aligned with the chronologies of the other dating techniques profiles magnetically enhanced throughout their depth and lacking any clear trend comprised group 2 here a mineral magnetic approach to dating was limited as the magnetic signal was diluted by a high sedimentation rate or impacted by local anthropogenic factors all profiles from england were included in group 3 because their magnetic depth profiles were influenced by natural sources of magnetic particles or specific sedimentary conditions and a longer industrial history and thus needed an individual interpretation however they still reflected the regional deposition history of industrial sources of ferrimagnetic particles overall magnetic parameters proved to be an efficient dating proxy with potential for recently aggrading rivers

weather radar observations of the hekla 2000 eruption cloud iceland the hekla eruption cloud on 26 27 february 2000 was the first volcanic cloud to be continuously and completely monitored advecting above iceland using the c band weather radar near the keflavik international airport real time radar observations of the onset advection and waning of the eruption cloud were studied using time series of ppi plan position indicator radar images including vmi normal echotop and cappi level 2 displays the reflectivity of the entire volcanic cloud ranges from 0 to 60 dbz the eruption column above the vent is essentially characterised by vmi normal and cappi level 2 values 30 dbz due to the dominant influence of lapilli and ash tephra on the overall reflected signal the cloud generated by the column was advected downwind to the north northeast it is characterised by values between 0 and 30 dbz and the persistence of these reflections likely result from continuing water condensation and freezing on ash particles echotop radar images of the eruption onset document a rapid ascent of the plume head with a mean velocity of 30 to 50 m s 1 before it reached an altitude of 11 12 km the evolution of the reflected cloud was studied from the area change in pixels of its highly reflected portions 30 dbz and tied to recorded volcanic tremor amplitudes the synchronous initial variation of both radar and seismic signals documents the abrupt increase in tephra emission and magma discharge rate from 18 20 to 19 00 utc on 26 february from 19 00 the 45 dbz and 30 45 dbz portions of the reflected cloud decrease and disappear at about 7 and 10 5 h respectively after the eruption began indicating the end of the decaying explosive phase the advection and extent of the reflected eruption cloud were compared with eyewitness accounts of tephra fall onset and the measured mass of tephra deposited on the ground during the first 12 h differences in the deposit map and volcanic cloud radar map are due to the fact that the greater part of the deposit originates by fallout off the column margins and from the base of the cloud followed by advection of falling particle in lower level winds

a statistical approach to evaluate the tephra deposit and ash concentration from puff model forecasts abstract in this paper we present a new statistical approach which provides tephra deposit load and ash concentration using puff a lagrangian model widely used to forecast volcanic ash dispersal during volcanic crisis we perform a parametric study in order to analyze the influence of each input parameter on model outputs for this test we simulate two eruptive scenarios similar to the 2001 scenario 1 and 1998 scenario 2 etna eruptions using high resolution weather data and a domain of 170 170 km results show that for both scenarios we are able to calculate the tephra deposit load and ash concentration but the use of millions of particles is required specifically up to 33 and 220 millions of particles were necessary to accurately predict the tephra deposit and ash concentration in air respectively this is approximately two orders of magnitude larger than the values typically considered running puff the parametric study shows that the horizontal diffusion coefficient the time step of the simulations the topography and the standard deviation of the particle distribution greatly affect the model outputs we also validate the model by best fit procedures results show a good comparison between field data of the 2001 etna eruption and puff simulations being inside 5 and 1 5 times the observed data comparable with results of eulerian models this work will allow to reliably outline the areas of contaminated airspace using puff or any other lagrangian model in order to define the no fly zone and ensure the safety aviation operations as required after the eyjafjallajokull eruption

fingerprinting upland sediment sources particle size specific magnetic linkages between soils lake sediments and suspended sediments accelerated erosion of fine grained sediment is an environmental problem of international dimensions erosion control strategies and targeting of mitigation measures require robust and quantitative identification of sediment sources here we use magnetic fingerprinting to characterize soils and examine their affinity with and contribution to suspended sediments transported within two subcatchments feeding bassenthwaite lake northwest england a high resolution soil magnetic susceptibility survey was made using a field susceptometer zh instruments sm400 probe combining the spatial and vertical down profile soil magnetic data a subset of soil profiles was selected for detailed laboratory based magnetic remanence analyses the magnetic properties of the catchment soils are highly particle size dependent magnetic analyses were performed on the 31 63 m fraction for particle size specific comparison both with the suspended sediments and lake sediments fuzzy cluster analysis groups the soil magnetic data into six clusters apparently reflecting variations in parent material and horizon type with three magnetically hard soils as unclassified outliers examination of the cluster affinity of the soils suspended sediments and lake sediments indicates that topsoils of the upper newlands valley and subsoils around keskadale beck are a major source of the newlands beck suspended load and the recent post nineteenth century sediments in the deep lake basin older lake sediments show strong affinity with a small number of the derwent suspended sediments and one of the glenderamackin soils a large number of derwent suspended sediments show no affinity with any of the soils or lake sediments instead forming a coherent discrete and statistically unclassified group possibly resulting from mixing between the magnetically hard subsoils of the medium to high altitude glenderamackin and troutbeck areas and softer lower altitude glenderamackin soils the lack of any affinity of these suspended sediments with the lake sediments may indicate deposition along the derwent flood plain and or in the shallow delta of lake bassenthwaite particle size specific magnetic fingerprinting is thus shown to be both highly discriminatory and quantitatively robust even within the homogeneous geological units of this catchment area such a methodological approach has important implications for small large scale catchment management where sources of sediment arising from areas with uniform geology have been difficult to determine using other approaches such as geochemical or radionuclide analyses

impacts of coal mining subsidence on the surface landscape in longkou city shandong province of china coal mining subsidence is a common human geological disaster that was particularly conspicuous in china it seriously restricts the sustainable development of mining areas and it not only damages land resources but also triggers a series of ecological and environmental problems that may result in social and economic issues this report studied the coal mining subsidence area of longkou in shandong province and uses digital elevation data dem of the mining area before subsidence in 1978 as the baseline elevation through image algorithms we obtained coal mining subsidence region data for 1984 1996 2000 and 2004 and with spatial data sources of the same period of tm etm and spot5 remote sensing images bp artificial neural network bpnn classification is used to extract surface landscape information in the subsidence area with the support of gis technology superimposing subsidence area on the surface landscape using the largest landscape ecology patch index landscape shape index landscape condensation index and the index of landscape distribution report analyzes the mining landscape changes before and after subsidence this study also carries on exploratory research with the landscape changes thereby providing a scientific basis for integrated prevention and treatment

geochemistry of large river suspended sediments silicate weathering or recycling tracer this study focuses on the major and trace element composition of suspended sediments transported by the world s largest rivers its main purpose is to answer the following question is the degree of weathering of modern river borne particles consistent with the estimated river dissolved loads derived from silicate weathering in agreement with the well known mobility of elements during weathering of continental rocks we confirm that river sediments are systematically depleted in na k ba with respect to the upper continental crust for each of these mobile elements a systematics of weathering indexes of river borne solids is attempted a global consistency is found between all these indexes important variations in weathering intensities exist a clear dependence of weathering intensities with climate is observed for the rivers draining mostly lowlands however no global correlation exists between weathering intensities and climatic or relief parameters because the trend observed for lowlands is obscured by rivers draining orogenic zones an inverse correlation between weathering intensities and suspended sediment concentrations is observed showing that the regions having the highest rates of physical denudation produce the least weathered sediments finally chemical and physical weathering are compared through the use of a simple steady state model we show that the weathering intensities of large river suspended sediments can only be reconciled with the silicate derived dissolved load of rivers by admitting that most of the continental rocks submitted to weathering in large river basins have already suffered previous weathering cycles a simple graphical method is proposed for calculating the proportion of sedimentary recycling in large river basins finally even if orogenic zones produce weakly weathered sediments we emphasize the fact that silicate chemical weathering rates and hence co2 consumption rates by silicate weathering are greatly enhanced in mountains simply because the sediment yields in orogenic drainage basins are higher hence the parameters that control chemical weathering rates would be those that control physical denudation rates

assessment of the influencing factors on subsidence at abandoned coal mines in south korea this study deals with the characteristics of subsidence and the relationships between the subsidence factors over abandoned coal mines in south korea the subsidence factors that were investigated were the dip angle and thickness of the coal bed mining depth depth of subsidence and subsidence area in 548 cases of subsidence that occurred throughout the country a close relationship between the type of subsidence and mining method was identified there was an intimate relation between the depth of subsidence and the dip angle of the coal bed while the subsidence area proved to be in proportion to the thickness of the coal bed and mining depth and was in inverse proportion to the dip angle of the coal bed

distinguishing sediments from the yangtze and yellow rivers china a mineral magnetic approach the yellow river and the yangtze river contribute 10 of the global fluvial sediment flux to the oceans proper characterization of the sediments of the two rivers is critical to the knowledge of their fate in the marginal seas of the west pacific ocean magnetic measurements have been made on bulk sediments as well as on separated particle size fractions of representative samples from the yellow and yangtze river estuaries with the purpose of providing an efficient means of differentiating both groups of river sediments from each other we found that on average the yangtze river estuary sediments have relatively higher ferrimagnetic mineral contents and ferrimagnetic to antiferromagentic ratios compared with the yellow river estuary sediments a diagram of saturated isothermal remanent magnetization sirm versus the demagnetization parameter s 100 can clearly distinguish sediments from the two rivers detailed magnetic measurements carried out on particle size fractions provide additional confirmation

operational prediction of ash concentrations in the distal volcanic cloud from the 2010 eyjafjallajokull eruption 1 during the 2010 eruption of eyjafjallajokull improvements were made to the modeling procedure at the met office uk enabling peak ash concentrations within the volcanic cloud to be estimated in this paper we describe the ash concentration forecasting method its rationale and how it evolved over time in response to new information and user requirements the change from solely forecasting regions of ash to also estimating peak ash concentrations required consideration of volcanic ash emission rates the fraction of ash surviving near source fall out and the relationship between predicted mean and local peak ash concentrations unresolved by the model to validate the modeling procedure predicted peak ash concentrations are compared against observations obtained by ground based and research aircraft instrumentation this comparison between modeled and observed peak concentrations highlights the many sources of error and the uncertainties involved despite the challenges of predicting ash concentrations the ash forecasting method employed here is found to give useful guidance on likely ash concentrations predicted peak ash concentrations lie within about one and a half orders of magnitude of the observed peak concentrations a significant improvement in the agreement between modeled and observed values is seen if a buffer zone accounting for positional errors in the predicted ash cloud is used sensitivity of the predicted ash concentrations to the source properties e g the plume height and the vertical distribution of ash at the source is assessed and in some cases seemingly minor uncertainties in the source specification have a large effect on predicted ash concentrations

volcanic ash concentration during the 12 august 2011 etna eruption mount etna in italy is one of the most active volcanoes in the world and an ideal laboratory to improve volcano ash monitoring and forecasting during the volcanic episode on 12 august 2011 an eruption column rose up to several kilometers above sea level asl and the volcanic plume dispersed to the southeast from the video surveillance system we were able to estimate variations in the column height peak value of 9 5 0 5 km above sea level with time we derived the time varying discharge rate peak value of 60 m3 s 1 and determined the ash concentration using a volcanic ash dispersal model the modeled ash concentration was compared with lidar measurements using different particle effective radius and differences are within the error bars volcanic ash concentrations range from 0 5 to 35 5 10 3 g m 3 the comparison highlights that to improve volcanic ash forecasting during volcanic crises it is necessary to take into account the time varying discharge rate of explosive eruptions

investigating the use of the saharan dust index as a tool for the detection of volcanic ash in seviri imagery abstract despite the similar spectral signatures of ash and desert dust relatively little has been done to explore the application of dust detection techniques to the problem of volcanic ash detection the saharan dust index sdi is routinely implemented for dust monitoring at some centres and could be utilised for volcanic ash detection with little computational expense thereby providing a product that forecasters already have some familiarity with to complement the suite of existing ash detection tools we illustrate one way in which the index could be implemented for the purpose of ash detection by applying it to three scenes containing volcanic ash from the 2010 eyjafjallajokull eruption iceland and the 2011 eruption of puyehue chile it was also applied to an image acquired over etna in january 2011 where a volcanic plume is clearly visible but is unlikely to contain any ash these examples demonstrate the potential of the sdi as a tool for ash monitoring under different environmental and atmospheric conditions in addition to presenting a valuable qualitative product to aid monitoring this work includes a quantitative assessment of the detection skill using a manually constructed expert ash mask the optimum implementation of any technique is likely to be dependent on both atmospheric conditions and on the properties of the imaged ash which is often unknown in a real time situation here we take advantage of access to a truth rarely available in a real time situation and calculate an ash mask based on the optimum threshold for the specific scene which is then used to demonstrate the potential of the sdi the sdi mask is compared to masks calculated from a simplistic implementation of the more traditional split window method again exploiting our access to the truth to set the most appropriate threshold for each scene and to a probabilistic method that is implemented without reference to the truth and which provides useful insights into the likely cloud ash contamination of each pixel since the sensitivity of the sdi and split window methods to the tailored thresholds was not tested such tailoring is unlikely to be possible in a real situation this study presents the maximum anticipated skill for the sdi in the context of the maximum skill anticipated for the split window method although both are likely to be lower in a real time situation the results for the sdi are comparable to those of the other methods with a true skill score of 80 02 for the eyjafjallajokull night time scene compared to 88 81 and 46 63 for the split window and probabilistic method respectively and 90 06 for the eyjafjallajokull day time scene compared to 97 61 and 56 96 for the puyehue image the sdi resulted in a true skill score of 74 85 while the split window approach achieved 99 62 these results imply that the sdi which is already implemented operationally at some centres for dust detection could be a useful complement to existing ash monitoring techniques

geology and coal bed methane resource potential of the gondwana barapukuria coal basin dinajpur bangladesh abstract with an area of 5 16 km2 the barapukuria coal deposit is one of the five largest gondwana coal basins in bangladesh and is located in the north west of the country close to the towns of dinajpur and saidpur the existence of the basin was initially indicated by a negative gravity anomaly in oil and gas exploration exploration for the deposit was commenced by the geological survey of bangladesh gsb with seven surface boreholes that confirmed the existence of a significant coal deposit the deposit occurs as an asymmetrical synclinal structure with an axis striking approximately n s the deposit is limited to the east by a large normal fault which has displaced archaean metamorphics against the gondwana sediments the coal bearing sediments are comprised of gondwana permian age sandstones siltstones subordinate carbonaceous shales and six correlated coal seams the gondwana sediments are unconformably overlain by tertiary and quaternary deposits against which the coal seams are successively subcropped to the west within the structural limits of the basin approximately 377 mt coal in situ has been quantified in the six coal seams that range in depth from 118 to 518 m below surface due to the synclinal nature of the deposit the upper coal seams designated i to v occur over diminishing areal extent with decreasing depth the principal seam of interest is the lowermost seam vi with a variable thickness across the deposit from 22 m in the northern part of the deposit to more than 42 m in the southern and eastern areas development of the barapukuria mine the country s first coal mine commenced in 1996 with the construction of two vertical shafts coal production from seam vi began in 2005 and continues at the present time seam vi coal is high volatile b bituminous rank about 34 mt of coal has been estimated as recoverable resources utilising descensional multi slice longwall mining the mine design and development have been severely constrained by adverse seam gradients and the presence of the overlying water bearing tertiary dupi tila sediments the potential of coal bed methane extraction has been investigated as an alternative to underground mining the study considers the barapukuria deposit in terms of its geological structure geothermal gradient and the rank porosity and permeability of the coal seams as determined by several phases of exploration of the area the methane content of the bituminous coal at barapukuria varies within the range 6 51 12 68 m3 t representing a potential resource of more than 5 gm3 of gas

the 1989 1990 eruption of redoubt volcano alaska impacts on aircraft operations abstract the december 1989 june 1990 eruption of redoubt volcano affected commercial and military air operations in the vicinity of anchorage alaska these effects were due to the direct impact of volcanic ash on jet aircraft as well as to the rerouting and cancellations of flight operations owing to eruptive activity between december and february five commercial jetliners were damaged from ash encounters the most serious incident took place on december 15 1989 when a boeing 747 400 aircraft temporarily lost power of all four engines after encountering an ash cloud as the airplane descended for a landing in anchorage while there were no injuries to passengers the damage to engines avionics and aircraft structure from this encounter is estimated at 80 million four additional encounters between jet aircraft and redoubt ash clouds occurred in the anchorage area on december 15 and 16 1989 and february 21 1990 none resulted in engine failure two additional encounters took place on december 17 1989 when jet airliners encountered the redoubt cloud over west texas at the time of these encounters the cloud was up to 55 hours old and had traveled in excess of 2 900 nautical miles 5 300 km following the december 15 encounters anchorage international airport remained open however most airline companies canceled operations for up to several days as communications between federal agencies and airlines improved and as a better understanding of the nature and behavior of ash rich eruption clouds was achieved most airlines resumed normal service by early january 1990 the resulting loss of revenue at anchorage international airport during several months following the eruption is estimated to total 2 6 million the impact on general aviation and military operations consisted mostly of cancellation and rerouting of flights

improving volcanic ash cloud detection by a robust satellite technique abstract automated and reliable satellite based techniques are strongly required for volcanic ash cloud detection and tracking in fact volcanic ash clouds pose a serious hazard for air traffic and the synoptic and possibly frequent coverage offered by satellites can provide exciting opportunities for monitoring activities as well as for risk mitigation purposes a new avhrr based technique for improved automatic detection of volcanic clouds by means of multi temporal analysis of historical long term satellite records has been recently proposed the technique basically rests on the robust avhrr techniques rat approach which is an innovative strategy of satellite data analysis devoted to a former characterisation of the measured signal in terms of expected value and natural variability and a further recognition of signal anomalies by an automatic unsupervised change detection step in this work an extension of this method to nighttime observations is presented by using thermal infrared information coming from avhrr bands centred approximately at 3 5 11 0 and 12 0 m results achieved for two recent eruptive events of mount etna occurred in may 2000 and in july 2001 seem to be encouraging showing clear improvements in terms of ash detection sensitivity as well as in terms of false alarms reduction the technique performance is also evaluated by comparison with the traditional split window brightness temperature difference method this exercise revealed a general improvement obtained by the proposed approach even though some common problems still remain unsolved the main merits of such an approach are its intrinsic self adaptability to different environmental natural observational conditions and its natural exportability also to different satellite sensors the results here presented show the benefits of such a technique especially when different observational conditions time of pass seasonal period atmospheric moisture solar illumination volcanic cloud composition satellite angles of view etc are considered the future prospects also in terms of possible operational scenarios coming from the implementation of such an approach on the new generation of satellite sensors like for example seviri aboard meteosat second generation platform are also discussed

coal mining impacts on water environs around the barapukuria coal mining area dinajpur bangladesh the present research makes an effort towards awareness of the impact of underground coal mining on water environment around the barapukuria coal mining area dinajpur by direct field investigation questionnaire survey and laboratory analysis for this research the three foremost errands have been mulled over which are the water level data analysis for 10 years from 2001 to 2011 ground water major parametric analysis and the questionnaire survey on the availability of ground water before and after coal mining operation the results of field and laboratory analysis show that the characteristics and concentrations of all the major physical and chemical parameters such as ph ec temperature hco3 no3 so4 2 cl na k mg2 ca2 and fe total are still tolerable for all purposes and also within the standard limit on the other hand the questionnaire survey and water level data analysis confirm almost similar results regarding the depletion of water level the water level has depleted more than 5 m from 2001 to 2011 therefore currently the availability of ground water is normal in the rainy and winter seasons but is slight problematic in the dry season where ground water was available at all times prior to coal mining in the area from these scenarios it is comprehensible that the ground water level moves downwards than earlier because of the excess pumping of water from the mine area besides the natural recharge condition is not enough and somewhere breaks off while some of the mines out areas are subsided consequently the upper part of the water bearing formations aquifer loses its porous and permeable properties resulting water recharging problem which is directly responsible for depleting the ground water level over the area moreover the water levels will also decline relative to the location depth recharge and discharge conditions of the mine both aerially and vertically while there is a typical relationship between the depth of mining and static water level which is water levels will decline more as the mine goes deeper therefore taking into account the current ground water condition and the depth of barapukuria coal mine this research implied that the water level will deplete more in day coming and the water crisis will be more for future thus this research recommends a sustainable guideline for long term planning and also suggests that regular monitoring with time to time more detail qualitative and quantitative assessments of water bodies in the area

use of goes thermal infrared imagery for eruption scale measurements soufriere hills montserrat goes two band ir data are used to estimate the magnitude of small eruption clouds 107 metric tonnes of total ash 105 tonnes of fine 1 25 m in diameter ash and 5 15 km asl the method is demonstrated on clouds from soufriere hills volcano montserrat in 1997 99 the clouds in early 1999 were much smaller were generally emplaced lower in the atmosphere and contained an order of magnitude less fine ash than 1997 clouds generated during the most intense phase of the eruption to date although goes has an excellent capability for large eruption clouds its use for smaller eruptions like montserrat highlights several shortcomings including atmospheric water vapor and instrument noise in spite of these shortcomings goes time series data can measure differences in intensity of eruptions and be of particular value in monitoring where ground based observations are sparse

simulations of tephra dispersal from the 1991 explosive eruptions of hudson volcano chile abstract the 1991 explosive eruptions of hudson volcano in southern chile produced 2 7 km 3 dense rock equivalent of basalt and trachyandesite tephra during the period august 8 15 the initial basaltic phase phase i august 8 9 produced a maximum column height of 12 km above sea level asl and tephra fallout was directed to the north and northeast by the prevailing winds the paroxysmal trachyandesitic phase phase ii august 12 15 involved at least three separate events with a maximum 18 km high asl eruption column inferred from satellite temperature data during the initial 24 h of this phase the plume was advected almost directly south before swinging towards the east as the wind changed direction the plume was ultimately directed to the southeast and stayed relatively fixed at this bearing for the remainder of the eruption these temporal variations in the main dispersal direction during the earlier stages of the phase ii eruption produced a much wider overall deposit than would be expected from a plume with a relatively fixed transport direction e g latter stages of phase ii the lagrangian ash tracking model puff was utilized to simulate the 1991 explosive eruptions and was able to successfully reproduce the aerial distribution and temporal evolution of the plumes the optimal agreement between the observed and simulated plumes occurs when the highest concentration of ash particles coincides with the tropopause a height that is typically lower than the maximum observed column heights for the 1991 eruptions gravitational settling of the laterally spreading umbrella region e g pinatubo 1991 may result in the concentration of ash at this level this may account for differences in column height estimates between ground or satellite based and lithic based models the plume associated with the paroxysmal phase august 12 15 1991 produced a multilayered deposit composed of alternating layers of fine ash and pumice lapilli the highly stratified nature of the fall deposit is likely the result of multiple eruptive events coupled with a time varying wind field a strongly changing wind direction that occurred during the earlier stages of the paroxysmal eruption could have produced variations in the dominant grain size being deposited between fine ash and pumice lapilli during individual eruptive sequences

improved prediction and tracking of volcanic ash clouds abstract during the past 30 years more than 100 airplanes have inadvertently flown through clouds of volcanic ash from erupting volcanoes such encounters have caused millions of dollars in damage to the aircraft and have endangered the lives of tens of thousands of passengers in a few severe cases total engine failure resulted when ash was ingested into turbines and coating turbine blades these incidents have prompted the establishment of cooperative efforts by the international civil aviation organization and the volcanological community to provide rapid notification of eruptive activity and to monitor and forecast the trajectories of ash clouds so that they can be avoided by air traffic ash cloud properties such as plume height ash concentration and three dimensional ash distribution have been monitored through non conventional remote sensing techniques that are under active development forecasting the trajectories of ash clouds has required the development of volcanic ash transport and dispersion models that can calculate the path of an ash cloud over the scale of a continent or a hemisphere volcanological inputs to these models such as plume height mass eruption rate eruption duration ash distribution with altitude and grain size distribution must be assigned in real time during an event often with limited observations databases and protocols are currently being developed that allow for rapid assignment of such source parameters in this paper we summarize how an interdisciplinary working group on eruption source parameters has been instigating research to improve upon the current understanding of volcanic ash cloud characterization and predictions improved predictions of ash cloud movement and air fall will aid in making better hazard assessments for aviation and for public health and air quality

circumpolar transport of a volcanic cloud from hekla iceland 1 hekla volcano iceland erupted on 17 august 1980 and emplaced a sulfur dioxide so2 cloud into the north polar stratosphere at a maximum altitude of 15 km the so2 is tracked using satellite data from the ultraviolet uv nimbus 7 total ozone mapping spectrometer n7 toms and the infrared ir high resolution infrared radiation sounder hirs 2 on the noaa tiros operational vertical sounder tovs platform the eruption emitted 0 5 0 7 tg of so2 which later split into three distinct clouds one of which circled the north pole at the perimeter of an atypically persistent arctic cyclone for six days impacting airspace on three continents separate clouds drifted across eastern russia alaska and canada maximum so2 columns derived from toms and hirs 2 accurately define the volcanic cloud s path and fit trajectories produced by the noaa hybrid single particle lagrangian integrated trajectory hysplit model providing confidence in the model when combined with the so2 measurements trajectory altitudes derived from hysplit provide robust estimates of the altitudes of the so2 clouds 8 15 km which would be elusive using either the satellite data or the trajectory model in isolation near coincident spectrally discrete uv and ir retrievals are compared in the volcanic cloud and indicate good agreement between toms and hirs 2 so2 columns for pixels with similar viewing geometry hekla eruptions which follow a pattern of early explosive venting of volcanic gases with significant stratospheric injection could play a role in promoting arctic ozone loss depending on the phase of the north atlantic oscillation during the eruption

near source doppler radar monitoring of tephra plumes at etna over the last twenty years mount etna has produced more than one hundred explosive events ranging from light ash emissions to violent sub plinian eruptions significant hazards arise from tephra plumes which directly threaten air traffic and generate fallout affecting surrounding towns and infrastructures we describe the first radar system named voldorad 2b fully integrated into a volcano instrumental network dedicated to the continuous near source monitoring of tephra emissions from etna s summit craters this 23 5 cm wavelength pulsed doppler radar is operated in collaboration between the observatoire de physique du globe de clermont ferrand opgc and the istituto nazionale di geofisica e vulcanologia osservatorio etneo ingv oe since 2009 probed volumes inside the fixed northward pointing conical beam total about 1 5 km in length covering the summit craters which produced all recent tephra plumes the backscattered power related to the amount of particles crossing the beam and particle along beam velocities are recorded every 0 23 s providing a proxy for the tephra mass eruption rate radar raw data are transmitted in real time to the volcano monitoring center of ingv oe in catania and are used to automatically release alerts at onset and end of eruptive events processed radar parameters are also made available from the voldorad database online http voldorad opgc fr in addition to eruptive crater discrimination by range gating relative variations of eruption intensity can be tracked including through overcast weather when other optical or infrared methods may fail to provide information short lived dense ash emissions can be detected as illustrated for weak ash plumes from the bocca nuova and new south east craters in 2010 the comparison with thermal images suggests that the front mushroom of individual ash plumes holds the largest particles coarse ash and small lapilli and concentrations at least within the first hundred meters for these short lived ash plumes the highest particle mass flux seems to occur typically within the first 10 s we also analyze data from the first lava fountain generating an ash and lapilli plume on 12 january 2011 that initiated a series of 25 paroxysmal episodes of the new south east crater until april 2012 we illustrate the pulsating behavior of the lava fountain and show that vertical velocities reached 250 m s 1 with brief peaks exceeding 300 m s 1 leading to mean and maximum tephra fluxes dre of 185 and 318 m3 s 1 with peaks exceeding 380 m3 s 1 respectively and a total volume of pyroclasts emitted during the lava fountain phase of 1 3 106 m3 finally we discuss capacities and limits of the instrument along with future work aimed at providing source term inputs to tephra dispersal models in order to improve hazard assessment and risk mitigation at etna

dam triggered organic carbon sequestration makes the changjiang yangtze river basin china a significant carbon sink worldwide dam building in large river basins has substantially altered the carbon cycle by trapping much of the riverine transported particulate organic carbon poc in terrestrial reservoirs here we take the changjiang yangtze river basin in which 50 000 dams were built over the past 50 years as an example to evaluate the effect of dam building on poc sequestration we report the characteristics elemental composition radiocarbon and stable carbon isotopic compositions and raman spectra of bulk poc in the lower changjiang from october 2007 to september 2008 and we estimate the poc sequestration induced by dam building since the 1950s for the changjiang basin using radiocarbon measurements we quantify the fraction of biospheric poc pocbio and petrogenic poc pocpetro in changjiang poc over the study period around 25 of the changjiang poc is radiocarbon dead pocpetro the remaining is pocbio with a mean radiocarbon age of 3 5 kyr studies on the east china sea ecs shelf along with an oxidation experiment suggest that prior to dam building the changjiang pocbio was significantly oxidized in the ecs margin in contrast high preservation of poc is observed in changjiang reservoirs combining our poc data with hydrometric data sets our study indicates that over the past five decades dam building may have largely shifted the changjiang poc burial site from the ecs margin to terrestrial reservoirs this shift in burial site preserved labile pocbio that would have been oxidized suggesting a new temporary carbon sink we estimate that dam building in the changjiang has sequestered 4 9 1 9 megatons pocbio every year since 2003 approximately 10 of the global riverine poc burial flux to the oceans

monitoring and modeling ice rock avalanches from ice capped volcanoes a case study of frequent large avalanches on iliamna volcano alaska abstract iliamna is an andesitic stratovolcano of the aleutian arc with regular gas and steam emissions and mantled by several large glaciers iliamna volcano exhibits an unusual combination of frequent and large ice rock avalanches in the order of 1 10 6 m 3 to 3 10 7 m 3 with recent return periods of 2 4 years we have reconstructed an avalanche event record for the past 45 years that indicates iliamna avalanches occur at higher frequency at a given magnitude than other mass failures in volcanic and alpine environments iliamna volcano is thus an ideal site to study such mass failures and its relation to volcanic activity in this study we present different methods that fit into a concept of 1 long term monitoring 2 early warning and 3 event documentation and analysis of ice rock avalanches on ice capped active volcanoes long term monitoring methods include seismic signal analysis and space and airborne observations landsat and aster satellite data was used to study the extent of hydrothermally altered rocks and surface thermal anomalies at the summit region of iliamna subpixel heat source calculation for the summit regions where avalanches initiate yielded temperatures of 307 to 613 k assuming heat source areas of 1000 to 25 m 2 respectively indicating strong convective heat flux processes such heat flow causes ice melting conditions and is thus likely to reduce the strength at the base of the glacier we furthermore demonstrate typical seismic records of iliamna avalanches with rarely observed precursory signals up to two hours prior to failure and show how such signals could be used for a multi stage avalanche warning system in the future for event analysis and documentation space and airborne observations and seismic records in combination with srtm and aster derived terrain data allowed us to reconstruct avalanche dynamics and to identify remarkably similar failure and propagation mechanisms of iliamna avalanches for the past 45 years simple avalanche flow modeling was able to reasonably replicate iliamna avalanches and can thus be applied for hazard assessments hazards at iliamna volcano are low due to its remote location however we emphasize the transfer potential of the methods presented here to other ice capped volcanoes with much higher hazards such as those in the cascades or the andes

observations of mt etna volcanic ash plumes in 2006 an integrated approach from ground based and polar satellite noaa avhrr monitoring system abstract mt etna in sicily italy is one of the world s most frequent emitters of volcanic plumes during the last ten years etna has produced copious tephra emission and fallout that have damaged the inhabited and cultivated areas on its slopes and created serious hazards to air traffic recurrent closures of the catania international airport have often been necessary causing great losses to the local economy recently frequent episodes of ash emission lasting from a few hours to days occurred from july to december 2006 necessitating a look at additional monitoring techniques such as remote sensing the combination of a ground monitoring system with polar satellite data represents a novel approach to monitor etna s eruptive activity and makes etna one of the few volcanoes for which this surveillance combination is routinely available in this work ash emission information derived from an integrated approach based on comparing ground and noaa avhrr polar satellite observations is presented this approach permits us to define the utility of real time satellite monitoring systems for both sporadic and continuous ash emissions using field data visible observations collection of tephra samples and accounts by local inhabitants the duration and intensity of most of the tephra fallout events were evaluated in detail and in some cases the order of magnitude of the erupted volume was estimated the ground data vs satellite data comparison allowed us to define five different categories of etna volcanic plumes according to their dimensions and plume height taking into account wind intensity using frequent and good quality satellite data in real time this classification scheme could prove helpful for investigations into a possible correlation between eruptive intensity and the presence and concentration of ash in the volcanic plume the development and improvement of this approach may constitute a powerful warning system for civil protection thus preventing unnecessary airport closures

provenance and climate changes inferred from magnetic properties of the sediments from the lower yangtze river china during the last 130 years abstract it is essential to have a clear scientific view on paleoclimate change and its potential environmental and socio economic impacts for the prediction of future climate change fluvial sediment is one of the best archives for the investigations of high resolution environmental variability and anthropogenic impacts on catchment over the last hundreds or even thousands years anthropocene in this study we examine magnetic properties of a 130 year fluvial sediment profile from an island in the main channel of the lower yangtze mainstream which aims to determine the connections between modern observational data and paleoclimate signals from sediments sediments from the upper yangtze river is characterized by high concentration of magnetite which is different from the middle reach the difference of magnetic properties allows us to trace particles in the lower reach back to upstream of the yangtze river climate change that reconstructed from physical properties of sediment susceptibility and mean grain size is comparable to those records in historical documents which provides a possible way to obtain precise ages the calibrated sedimentation rate reflects long term variation of flood drought events over the catchment which is dominantly controlled by the climate circulation of pacific the enhanced human impacts since 1950s especially in the mid lower reaches are observed therefore riverine sediment not only contains paleoclimate information but also reflects human activities

sensitivity analysis for the gis based mapping of the ground subsidence hazard near abandoned underground coal mines ground subsidence around abandoned underground coal mines can cause much loss of life and property we analyze factors that can affect ground subsidence around abandoned mines in jeongahm in kangwon do by sensitivity analysis in geographic information system gis spatial data for the subsidence area topography and geology and various ground engineering data were collected and used to make a factor raster database for a ground subsidence hazard map to determine the importance of extracted subsidence related factors frequency ratio model and sensitivity analysis were employed sensitivity analysis is a method for comparing the combined effects of all factors except one sensitivity analysis and its verification showed that using all factors provided 91 61 accuracy the best accuracy was achieved by not considering the groundwater depth 92 77 and the worst by not considering the lineament 85 42 the results show that the distance from the lineament and the distance from the drift highly affected the occurrence of ground subsidence and the groundwater depth land use and rock mass rating had the least effects thus we determined causes of ground subsidence in the study area and this information could help in the prediction of ground subsidence in other areas

estimation of the 2002 mount etna eruption cloud radiative forcing from meteosat 7 data abstract on 27th october 2002 after 15 months of small activity the mount etna located on the island of sicily italy 37 73 n 15 00 e erupted undergoing one of its most vigorous eruptions in years during a few days europe s highest and most active volcano hurled lava and spewed significant amounts of ash and trace gases into the atmosphere the smoke and ash plume originating from the volcano stretched from the sicily to the north african coast the plume from the volcano has been identified and tracked using half hourly meteosat 7 visible infrared and water vapor imagery in order to estimate the radiative forcing produced by the introduction of the volcanic cloud in a previously clear sky our results indicate that while the volcanic cloud has introduced a well discernable radiative perturbation the magnitude of the shortwave volcanic forcing appears in the range of the one introduced by large clouds above the mediterranean sea by contrast the perturbation generated in the longwave spectrum at the top of the atmosphere is larger than the one introduced by large meteorological clouds

an experimental simulation of volcanic ash deposition in gas turbines and implications for jet engine safety abstract the protracted grounding of commercial aircraft throughout europe due to the eyjafjallajokull volcanic eruption in iceland april 2010 has alerted the public to the potential dangers of aircraft encounters with ash clouds one of the most serious issues is the failure of jet turbines due to the deposition of molten silicate ash particles on hot turbine components in this study we highlight the influence of volcanic ash composition crystal glass ratio and resulting bulk viscosity on the interaction of ash particles with hot turbine blades and vanes a range of volcanic materials are used to simulate ash melting during transport through the combustor and deposition on a turbine blade of nickel superalloy material commonly used for the hot components in jet engines the results show how on blade accumulation of molten particles can lead to efficient adhesion wetting and subsequent rapid accumulation of further molten material in some circumstances in other cases particles form a cinder like layer or entirely bounce off the blade any deposits will disrupt the air flow in the turbine clog the cooling system and eventually cause the engine to stall however the cinder deposits can be removed in our experiments as well as in flight for a real engine by shutting off the heat source allowing the deposit to quench and dislodge by thermal stress cracking however this currently recommended airplane safety procedure will not work for more basaltic melts which wet the blade surface more efficiently our experiments demonstrate how the nature of the incoming ash particle strongly influences the type of deposit formed the important parameters being bulk ash composition crystal proportion and particle size

direct injection of water vapor into the stratosphere by volcanic eruptions while theoretical studies show that water vapor wv can be directly injected into the stratosphere during a volcanic eruption few observations of such a phenomenon exist the microwave limb sounder observed stratospheric injection of wv following the 2015 calbuco eruption lower stratospheric mixing ratios exceeded 10 ppmv for a few days downwind of the injection location plume transport is confirmed by back trajectory modelling due to the short duration and limited spatial extent of the enhancement climatic impact is expected to be negligible this letter provides spatiotemporal analysis of a volcanogenic pulse of lower stratospheric wv as it dispersed the inferred mass of stratospheric wv from this eruption of 2 mt and the rapid evanescence of the enhancement is similar to what has been observed for other eruptions suggesting that injection by moderately explosive eruptions is not an effective mechanism for large scale stratospheric hydration

evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 eyjafjallajokull eruption using lidar observations and name simulations 1 the eyjafjallajokull volcano in iceland erupted explosively on 14 april 2010 emitting a plume of ash into the atmosphere the ash was transported from iceland toward europe where mostly cloud free skies allowed ground based lidars at chilbolton in england and leipzig in germany to estimate the mass concentration in the ash cloud as it passed overhead the uk met office s numerical atmospheric dispersion modeling environment name has been used to simulate the evolution of the ash cloud from the eyjafjallajokull volcano during the initial phase of the ash emissions 14 16 april 2010 name captures the timing and sloped structure of the ash layer observed over leipzig close to the central axis of the ash cloud relatively small errors in the ash cloud position probably caused by the cumulative effect of errors in the driving meteorology en route result in a timing error at distances far from the central axis of the ash cloud taking the timing error into account name is able to capture the sloped ash layer over the uk comparison of the lidar observations and name simulations has allowed an estimation of the plume height time series to be made it is necessary to include in the model input the large variations in plume height in order to accurately predict the ash cloud structure at long range quantitative comparison with the mass concentrations at leipzig and chilbolton suggest that around 3 of the total emitted mass is transported as far as these sites by small 100 m diameter ash particles

aviation response to a widely dispersed volcanic ash and gas cloud from the august 2008 eruption of kasatochi alaska usa 1 the extensive volcanic cloud from kasatochi s 2008 eruption caused widespread disruptions to aviation operations along pacific oceanic canadian and u s air routes based on aviation hazard warnings issued by the national oceanic and atmospheric administration u s geological survey the federal aviation administration and meteorological service of canada air carriers largely avoided the volcanic cloud over a 5 day period by route modifications and flight cancellations comparison of time coincident goes thermal infrared tir data for ash detection with ozone monitoring instrument omi ultraviolet data for so2 detection shows congruent areas of ash and gas in the volcanic cloud in the 2 days following onset of ash production after about 2 5 days the area of so2 detected by omi was more extensive than the area of ash indicated by tir data indicating significant ash depletion by fall out had occurred pilot reports of visible haze at cruise altitudes over canada and the northern united states suggested that so2 gas had converted to sulfate aerosols uncertain about the hazard potential of the aging cloud airlines coped by flying over under or around the observed haze layer samples from a nondamaging aircraft encounter with kasatochi s nearly 3 day old cloud contained volcanic silicate particles confirming that some fine ash is present in predominantly gas clouds the aircraft s exposure to ash was insufficient to cause engine damage however slightly damaging encounters with volcanic clouds from eruptions of reventador in 2002 and hekla in 2000 indicate the possibility of lingering hazards associated with old and or diffuse volcanic clouds

influence of particle aggregation on deposition of distal tephra from the may 18 1980 eruption of mount st helens volcano the may 18 1980 eruption of mount st helens msh produced an extensive ashfall deposit in washington idaho and montana with a minumum volume of 0 55 km3 tephra an unusual feature of the deposit is the occurrence of a second thickness maximum 325 km ene of msh near ritzville washington grain size and component abundance analysis of samples along the main dispersal axis indicates that ash in this region is very fine grained mean size 22 m poorly sorted polymodal and rich in glass shards and pumice fragments a computer simulation of ash fallout from an atmospherically dispersed eruption plume was developed to evaluate various hypotheses for the origin of the distal ash characteristics particularly the thickness versus distance relationship the model was constrained by observations of the eruption column height elevation of major ash transport lateral spreading of the eruption plume and atmospheric wind structure in the vicinity of msh results of different simulations indicate that the second thickness maximum cannot be attributed to either decreased wind velocities over central washington or injection of fine ash above the horizontal wind velocity maximum near the tropopause for the model to fit the observed characteristics of the deposit significant particle aggregation of ash finer than 63 m must be invoked the best fit occurs when ash less than 63 m is aggregated into particles several hundred microns in diameter with a settling velocity of 0 35 m s support for this process comes from the observation and collection of fragile ash clusters of similar size which fell at pullman washington during the may 18 eruption sorem 1982 the premature fallout of fine ash as particle aggregates is a fundamental process in the origin of the grain size characteristics variations in component abundances and thickness versus distance relationship of the may 18 msh ash fall deposit

temporal and spatial variations in magnetic properties of suspended particular matter in the yangtze river drainage and their implications abstract as the largest river of china the yangtze river transports large amounts of sediments to the adjacent oceans provenance of these ancient marine sediments can only be deciphered when the source to sink process of modern sediments in the yangtze river is fully understood many methods have been used to study the provenance of river sediment and an environmental magnetic method is applied in this study because of its fast nondestructive advantages magnetic properties of suspended particulate matter spm along the yangtze river were measured to provide a holistic understanding about magnetic properties of sediments in this river and its controlling factors the results indicate that the dominant magnetic mineral in spm is magnetite with a small contribution of hematite and goethite significant spatial variation was observed in most of the magnetic parameters which primarily reflects the distribution of major geologic units along the drainage area of the river anthropogenic influences are also recorded in the magnetic parameters the three gorges dam results in a dramatic decrease of magnetic minerals in the downstream reaches since its construction in 2003 in addition small variations in magnetic properties of spm are found along water depth together with a clear seasonal shift at datong station this seasonal variation of magnetic properties of spm is driven by variability in both hydrology and source contributions this complicates the use of magnetic parameters for provenance studies magnetic properties of sediments in rivers are capable of tracing provenance areas but caution must be taken into account

aster watches the world s volcanoes a new paradigm for volcanological observations from orbit onboard nasa terra spacecraft is one of the most sophisticated earth observing instruments ever flown the advanced spaceborne thermal emission and reflection radiometer aster created as part of a joint project between the japanese ministry of economy trade and industry and nasa this instrument consists of three independent bore sighted telescopes with 14 channels in the visible near infrared and thermal infrared regions capable of being pointed up to 22 5 off nadir in addition there is an additional backward looking visible channel telescope for stereo photogrammetric observations the spatial resolutions are 15 m pixel in the visible 30 m pixel in the near ir and 90 m pixel at thermal wavelengths and the swath width is 60 km aster instrument offers unprecedented opportunities for observing volcanoes and their activity from low earth orbit it is the purpose of this short paper to introduce aster to the volcanological community highlight its capabilities advantages and limitations and to show some examples of aster data and related analyses we will also explain how users can readily access aster data

early evolution of a stratospheric volcanic eruption cloud as observed with toms and avhrr this paper is a detailed study of remote sensing data from the total ozone mapping spectrometer toms and the advanced very high resolution radiometer avhrr satellite detectors of the 1982 eruption of el chichon mexico the volcanic cloud atmosphere interactions in the first four days of this eruption were investigated by combining ultraviolet retrievals to estimate the mass of sulfur dioxide in the volcanic cloud krueger et al 1995 with thermal infrared retrievals of the size optical depth and mass of fine grained 1 10 m radius volcanic ash wen and rose 1994 our study provides the first direct evidence of gravitational separation of ash from a stratospheric gas rich plinian eruption column and documents the marked differences in residence times of volcanic ash and sulfur dioxide in volcanic clouds the eruption column reached as high as 32 km carey and sigurdsson 1986 and was injected into an atmosphere with a strong wind shear which allowed for an observation of the separation of sulfur dioxide and volcanic ash the upper more sulfur dioxide rich part of the cloud was transported to the west in the stratosphere while the fine grained ash traveled to the south in the troposphere the mass of sulfur dioxide released was estimated at 7 1 109 kg with the mass decreasing by approximately 4 1 day after the peak the mass of fine grained volcanic ash detected was estimated at 6 5 109 kg amounting to about 0 7 of the estimated mass of the ash which fell out in the mapped ash blanket close to the volcano over the following days 98 of this remaining fine ash was removed from the volcanic cloud and the effective radius of ash in the volcanic cloud decreased from about 8 m to about 4 m

volcanic ash model verification using a klyuchevskoi eruption satellite imagery of volcanic ash is used to verify the air resources laboratory arl time dependent three dimensional volcanic ash forecast transport and dispersion vaftad model vaftad forecasts are included in volcano hazards alert messages issued as an aid to aircraft operations for ash clouds that reach flight levels of 6 km or higher and may drift hundreds to thousands of kilometers from an explosive volcanic eruption vaftad is run by users connected through internet to a workstation at arl using screen prompted input and is applicable globally model output gives charts of the forecast ash cloud which are phone faxed back to the user and made available for public distribution over various weather information distribution systems and internet volcanic ash model verification is essential for interpreting ash cloud forecasts and applying them for decision making the vaftad model verification is detailed using a september 1994 eruption of the klyuchevskoi volcano on kamchatka peninsula in eastern russia both the downwind extent of the ash cloud along the main flow axis and the ash cloud width perpendicular to the main flow axis seen on satellite imagery compared remarkably well with the vaftad calculations that used eruption source information and archived meteorological analyses as model input

detecting the footprint of a longwall mine panel claimed to infringe on a permit boundary at the soma darkale coalfield manisa turkey using surface fractures and microgravity measurements a coal mine panel claimed to infringe on a permit boundary or to create an hazard after subsidence has been the subject of lawsuits we study at the soma darkale coalfield manisa turkey the footprint of a lignite coal mine panel at a depth of about 150 200 m by mapping all of the surface fractures we could observe and by developing a post subsidence density model that we verified through gravity measurements with positive bouguer anomaly with the analysis of the fracture map and the gravity data we were able to identify the footprint of a mine panel from the effect of the anomalous mass due to denser overburden material filling up the space after the extraction of less dense lignite whereas using empirical methods like the so called limit line approach to evaluate the extent of the area where mining can have subsidence induced surface fracturing one could not recognize for certain infringement of permit boundaries the orientations of the fractures we mapped at the ground surface the bouguer gravity map and a test borehole indicated the presence and dimensions of a coal panel in dispute the presented approach based on gravity method and fracture observations may be an example to help settle conflicts related to the position of the longwall mine panel

magnetic properties of sediments from major rivers aeolian dust loess soil and desert in china abstract the continent of china delivers huge terrigenous sediments to the east asian marginal seas and northwest pacific ocean by riverine and aeolian inputs which exerts a great impact on marine sedimentation primary productivity and biogeochemical cycle in this study magnetic properties of the sediments from the changjiang and huanghe river systems were investigated in order to provide potential provenance tracers besides the top soil from the loess plateau taklimakan desert sand and dust storm particles were comparatively studied to reveal the controls of magnetic properties in various depositional environments the changjiang sediment is characterized by the highest concentration of magnetic minerals and the largest variations for most magnetic parameters while the huanghe sediment has much lower content of magnetic minerals the loess soil sediment yields the highest frequency dependent susceptibility fd while the aeolian dust has similar magnetic susceptibility but higher saturation isothermal remnant magnetization and lower anhysteretic remnant magnetization arm the desert sand has the lowest values of all magnetic parameters indicating the lowest ferrimagnetic mineral concentration with coarser grain size the magnetic properties of the changjiang sediments are primarily determined by the diversity of lithology in its large drainage basin while the sediment grain size basically accounts for the variation of magnetic parameters in the huanghe sediment the gradual increase of fd towards the lower reaches suggests it may potentially indicate grain size fractionation in the catchments although some magnetic parameters can apparently discriminate the origins of fluvial and aeolian sediments reliable magnetic proxy for distinguishing sediment origins in marine environment can only be established if hydrodynamic differentiation and post depositional diagenetic alteration of magnetic minerals are fully understood

spatial distribution of volcanic ash deposits of 2011 puyehue cordon caulle eruption in patagonia as measured by a perturbation in ndvi temporal dynamics abstract volcanic ash fallout is a recurrent environmental disturbance in forests arid and semi arid rangelands of patagonia south america the ash deposits over large areas are responsible for several impacts on ecological processes agricultural production and health of local communities public policy decision making needs monitoring information of the affected areas by ash fallout in order to better orient social economic and productive aids the aim of this study was to analyze the spatial distribution of volcanic ash deposits from the eruption of puyehue cordon caulle in 2011 by identifying a sudden change in the normalized difference vegetation index ndvi temporal dynamics defined as a perturbation located in the time series we applied a sparse wavelet transform using the basis pursuit algorithm to ndvi time series obtained from the moderate resolution image spectroradiometer modis sensor to identify perturbations at a pixel level the spatial distribution of the perturbation promoted by ash deposits in patagonia was successfully identified and characterized by means of a perturbation in ndvi temporal dynamics results are encouraging for the future development of a new platform in combination with data from forecasting models and tracking of ash cloud trajectories and dispersion to inform stakeholders to mitigate impact of volcanic ash on agricultural production and to orient public intervention strategies after a volcanic eruption followed by ash fallout over a wide region

effects of mining subsidence on masonry buildings in zonguldak hard coal region in turkey gallerias are the underground constructed results of mining as these space in underground layers collapse horizontal and vertical ground movements occur and movement which may reach the earth s surface are known as mining subsidence the result of underground displacement may cause surface ground movement which can be detrimental to masonry buildings especially in hard coal regions thorough familiarity with general and regional characteristics of an affected area can assist reduction of the effects zonguldak and the nearby settlement area with a population of 300 000 constitute the centre of a hard coal basin where extensive mining has a history extending through 160 years mining constitutes the main economic activity in this region and consequently influences every aspect of life this study s intent is to identify the effects of mining subsidence on masonry buildings in the mining area of kozlu zonguldak turkey and illustrate them with selected images of damaged masonry buildings also included are satellite and mining galleria images

quantification of volcanic cloud top heights and thicknesses using a train observations for the 2008 chaiten eruption new evidence of vertically thin 10 km ash clouds from the may 2008 chaiten eruption in southern chile is presented a train remote sensors were used to measure high resolution volcanic cloud top heights vcths during the explosive phase 2 10 may 2008 of the eruption ash clouds were identified using a reverse absorption technique applied to hyperspectral measurements taken by the atmospheric infrared sounder once identified heights and thicknesses were derived from the cloud aerosol lidar with orthogonal polarization caliop instrument as these two instruments are part of the same constellation of satellites coincident retrievals are routinely possible collocation of the data allowed for detection of volcanic ash within caliop profiles using a simple thresholding algorithm vcth and thickness were derived from the caliop profiles a total of 12 vcth measurements ranging from 3 7 to 16 6 km have been derived back trajectories from the hybrid single particle lagrangian integrated trajectory dispersion model were used as a check on volcanic origin of the detected ash clouds ensemble forward trajectories were generated to demonstrate how the new data could be used to improve volcanic ash advisory center operations the findings reported here demonstrate several cases where low level ash was not recorded previously and include observations of thin ash clouds at large distances 4000 km from the volcano

failures in detecting volcanic ash from a satellite based technique abstract immediate and accurate detection of airborne volcanic ash is an operational imperative of the aviation industry especially jet aircraft ash encounters place passengers aboard these aircraft at severe risk and significantly impact via forced rerouting both the safety and profit margins of freight carriers due to their limited fuel supply moreover the airlines can suffer high economic costs for repair and replacement of equipment operational detection and tracking of volcanic ash by most national weather services has relied heavily on a split window differencing technique of thermal longwave infrared channels on currently operational satellites unfortunately prior work on volcanic ash detection has not emphasized the dynamical interaction between the erupting volcano and the effects of overlying atmospheric water vapor phreatic and phreatomagmatic water sources six volcanic ash eruptions from around the globe were chosen for study because they have wide variation in ambient atmospheric water vapor available ground and surface water and different magma types results show that the present differencing technique is not uniformly effective in properly classifying volcanic ash pixels in the satellite scene and often falsely interprets meteorological clouds as volcanic ash clouds and conversely moreover it is not always a robust early detector an operational aviation requirement seasonal variability in global integrated atmospheric water vapor coupled with the geographical distribution of currently active volcanoes suggests the concerns discussed herein with regard to six specific eruptions have applicability to the global aviation industry operational implications are discussed and a strategic proposal is presented on necessary steps to improve detection

geochemical behavior assessment and apportionment of heavy metal contaminants in the bottom sediments of lower reach of changjiang river abstract heavy metal contamination of bottom sediments of the changjiang river is widely reported however the potential source and methods of transportation of these heavy metals in the contaminated sediments is poorly defined this paper examines the correlation between heavy metals and geochemical indices including fe2o3 al2o3 total organic carbon toc and black carbon bc as well as magnetic susceptibility ms using these indices we investigate the contamination characteristics of heavy metals in the sediments by with principal component analysis pca results from 83 sediment samples collected in the lower reach of changjiang river from nanjing to shanghai show that the first principal component accounts for 52 23 of the total variance corresponding to the heavy metals co cr cu ni and zn and conservative components of fe2o3 al2o3 and toc this result indicates that heavy metal distributions are controlled by the transportation and sedimentation of fine particles which is also confirmed by particle size analysis the second principal component explains 24 81 of the variance and is dominated by cd pb and ms which collectively result chiefly from industrial and transportation activities and for ms fly ash production the third principal component accounts for 7 91 of the variance and corresponds solely to hg principal component analysis multiple linear regression pca mlr was used to estimate the contribution of the three principal components to each heavy metal pca mlr results suggest that more than 50 of co cr cu ni and zn were influenced by the particle size effect particle size effect and fly ash account for 37 1 and 27 7 of as cd and pb were mainly explained by fly ash 98 9 of hg was related to pc3 which represented black carbon bc our study indicates that the combination of geochemical and multivariable statistical methods clearly characterizes the geochemistry of heavy metals in sediment of the lower reaches of the changjiang river and suggests that power plants are the main source of heavy metal pollution

estimates of total ash content from 2006 and 2009 explosion events at bezymianny volcano with use of a regional atmospheric modeling system abstract the december 24 2006 and december 16 2009 strong explosion events at bezymianny volcano kamchatka peninsula were accompanied by extensive ash falls in proximal and medium distal area

the effect of etna volcanic ash clouds on the maltese islands abstract in this paper we have studied in depth the effect of etna volcanic ash clouds on the maltese islands research was carried out to gather information about etna s eruptions that impacted the maltese islands starting with historical eruptions dating back to the 14th century continuing to present day a statistical approach was utilized to provide tephra deposit load and ash concentration using puff a model which simulates the transport dispersion and sedimentation of volcanic ash three different eruptive scenarios that characterize etna s recent activity were considered the first scenario representing the 2001 eruption sc1 the second scenario representing the july 1998 eruption sc2 whilst the third scenario represents the recent activity in 2011 2012 sc3 we found that the time taken for the volcanic ash cloud to reach the maltese islands when the wind direction is toward the south west ranges from 4 to 6 h the probability that an etna volcanic cloud reaches malta during an eruption is about 15 per annum the now calibrated model may be now used to produce deposit load and cumulative columnar load i e summation from maximum height of volcanic cloud to ground of volcanic ash in atmosphere for the maltese area and help the aviation authorities and malta airport to make decisions during etna eruptions this will be of direct use to local communities and aviation

paleocurrent analysis for the late pleistocene holocene incised valley fill of the yangtze delta china by using anisotropy of magnetic susceptibility data abstract anisotropy of magnetic susceptibility ams analysis has been conducted on samples from borehole core cm 97 from the yangtze river changjiang incised valley fill china to determine the paleocurrent directions to help in reconstructing sedimentary paleoenvironments borehole cm 97 consists of fluvial unit 1 estuarine units 2 6 and deltaic units 7 9 sediments after the last glacial maximum in ascending order the ams results show that the paleocurrent directions for the tide dominated estuarine and deltaic sediments were westerly or northwesterly directed flood tide dominated but give no definite trend for the fluvial sediments comparison between the paleocurrent directions inferred from primary sedimentary structures and in situ ams data shows that they are in good agreement confirming the applicability of ams as a good paleocurrent indicator for sediments deposited in coastal tide dominated environments considering that these sediments were strongly tide influenced and the tidal pattern since 12 kyr bp has not changed significantly we think that the westerly or northwesterly current direction most probably resulted from flood tidal currents and the sedimentary paleoenvironment was a flood tide dominated estuary or delta additionally it has been found that downhole changes of some ams parameters including the mean magnetic susceptibility k the corrected anisotropy degree p j and the magnetic foliation f clearly mark the defined stratigraphic boundaries in the borehole this further extends the validity of ams as a good stratigraphic marker in addition to its long known credibility as a sensible paleocurrent recorder

discrimination in magnetic properties of different sized sediments from the changjiang and huanghe estuaries of china and its implication for provenance of sediment on the shelf abstract provenance discrimination of marine sediments is an important topic in marine geology although the catchments of the changjiang and huanghe rivers are regarded as the main sources of sediments on the shelves of the china sea identification of detailed sediment provenance is necessary for understanding sediment transport patterns and the paleoenvironment magnetic properties of both bulk sediment samples and different sized particles from the changjiang and huanghe estuaries are studied to discuss the origin of the sediments the results show that the sediments are dominated by ferrimagnetic magnetite with a minor content of anti ferromagnetic minerals such as hematite and a higher concentration of ferrimagnetic minerals is observed for the changjiang estuary sediments the crystal grains of ferrimagnetic minerals in the changjiang estuary are coarser than those in the huanghe estuary whereas superparamagnetic grains significantly contribute to the huanghe sediments magnetic parameters of sirm soft and arm from different sized particles present more obvious differences than these parameters from bulk particles and s 100 and s 300 for both bulk samples and different sized particles show distinct differences between the sediments from the two estuaries therefore the latter parameters are more useful to distinguish sediment origins a comparison of the magnetic properties of sediments in these two estuaries with those on the shelves of the adjacent china sea also suggests that the analysis of sediment magnetic properties is effective to identify sediment provenances

anatomy of 1986 augustine volcano eruptions as recorded by multispectral image processing of digital avhrr weather satellite data eighteen digital avhrr advanced very high resolution radiometer data sets from noaa 6 and noaa 9 polar orbiting satellites recorded between 27 march and 7 april 1986 depict the eruptive activity of augustine volcano located 280 km sw of anchorage alaska the synoptic view resolution of either 1 1 or 4 4 km frequent coverage often twice a day and multispectral coverage five bands 0 58 0 68 0 72 1 1 3 55 3 93 10 5 11 3 and 11 5 12 5 m makes the avhrr broadly applicable to analyzing explosive eruption clouds the small scale of the augustine activity column heights of 2 13 km and eruption rates of 2x106 8x107 metric tonnes day facilitated intensive multispectral study because the plumes generally covered areas within the 550x550 km area of one easily manipulated image field hourly ground weather data and twice daily radiosonde measurements from stations surrounding the volcano plus numerous volcanological observations were made throughout the eruption providing important ground truth with which to calibrate the satellite data the total erupted volume is estimated to be at least 0 102 km3 the pattern of changing eruption rates determined by satellite observations generally correlate with more detailed estimates of explosion magnitudes multispectral processing techniques were used to distinguish eruption clouds from meteorological clouds variable weather during the augustine eruption offered an opportunity to test various trial algorithms a ratio between thermal ir channels four and five served to delineate the ashbearing eruption plumes from ordinary clouds future work is needed to determine whether the successful multispectral discrimination is caused by wavelength dependent variable emission of silicate ash or reflects a spectral role of sulfuric acid aerosol in the plume

puff a high resolution volcanic ash tracking model this paper presents a volcanic ash tracking model referred to as puff the model was developed to simulate the movement of airborne ash in near real time following an eruption for the purposes of hazard warning the model tracks particles through a lagrangian formulation of advection fallout and turbulent diffusion using a random walk technique three recent eruption events are simulated using archived data avhrr images from these events are used for comparison and to validate model results

analyses of in situ airborne volcanic ash from the february 2000 eruption of hekla volcano iceland 1 a mcdonnell douglas dc 8 nasa research aircraft inadvertently flew into an airborne volcanic ash plume from the 26 february 2000 eruption of hekla volcano filter samples from the aircraft were compared with normal use and pristine clean filters using sem energy dispersive x ray spectrometer and nicolet ftir spectrophotometer analyses these analyses confirm that the dc 8 encountered airborne volcanic ash from hekla volcano this result is supported by independent onboard heated aerosol observations at the time of the encounter the analyses further demonstrate the ambiguous nature of the dual band thermal ir split window method for detecting volcanic ash from the point of view of aviation safety they also highlight the utility of in situ aircraft filter based observations of volcanic aerosols for scientific purposes