low pressure differentiation of tholeiitic lavas as recorded in segregation veins from reykjanes iceland lanzarote canary islands and masaya nicaragua segregation veins are common in lava sheets and result from internal differentiation during lava emplacement and degassing they consist of evolved liquid most likely replaced by gas filter pressing from a 50 crystallised host lava pairs of samples host lavas and associated segregation veins from the reykjanes peninsula iceland lanzarote canary islands and the masaya volcano nicaragua show extreme mineralogical and compositional variations mgo in host lava segregation veins and interstitial glass ranges from 8 10 wt 3 6 wt and to less than 0 01 wt respectively these samples allow the assessment of the internal lava flow differentiation mechanism since both the parental and derived liquid are known in addition to the last magma drops in the form of late interstitial glasses the mineralogical variation mass balance calculated from major and trace element composition and transitional metal partition between crystals and melts are all consistent with fractional crystallisation as the dominant differentiation mechanism the interstitial glasses are highly silicic sio2 70 80 wt and represent a final product of high degree 75 97 fractional crystallisation of olivine tholeiite at a pressure close to one atmosphere the tholeiitic liquid line of decent and the composition of the residual melts are governed by the k2o na2o of the initial basaltic magma the granitic minimum is reached if the initial liquid has a high k2o na2o whereas trondhjemitic composition is the final product of magma with low initial k2o na2o

total co2 output from vulcano island aeolian islands italy 1 total co2 output from fumaroles soil gas bubbling gas discharges and water dissolved gases discharged from the island was estimated for vulcano island italy the co2 emission from fumaroles from the la fossa summit crater was estimated from the so2 crater output while co2 discharged through diffuse soil emission was quantified on the basis of 730 measurements of co2 fluxes from the soil of the island performed by using the accumulation chamber method the results indicate an overall output of 500 t day 1 of co2 from the island the main contribution to the total co2 output comes from the summit area of the la fossa cone 453 t day 1 with 362 t day 1 from crater fumaroles and 91 t day 1 from crater soil degassing the release of co2 from peripheral areas is 20 t day 1 by soil degassing palizzi and istmo areas mainly an amount comparable to both the contribution of water dissolved co2 6 t day 1 as well as to seawater bubbling co2 4 t day 1 measured in the istmo area presented data september 2007 refer to a period of moderate solphataric activity when the fumaroles temperature were 450 c and gas water molar ratio of fumaroles was up to 0 16 the calculated total co2emission allows the estimation of the mass release and related thermal energy from the volcanic hydrothermal system

dynamics of outgassing and plume transport revealed by proximal unmanned aerial system uas measurements at volcan villarrica chile volcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing and on geological timescales constitute an important source of volatiles to the earth s atmosphere measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geochemical cycles however significant gaps remain in our global inventories of volcanic emissions particularly for co2 which requires proximal sampling of a concentrated plume for those volcanoes where the near vent region is hazardous or inaccessible unmanned aerial systems uas provide a robust and effective solution to proximal sampling of dense volcanic plumes in extreme volcanic environments here we present gas compositional data acquired using a gas sensor payload aboard a uas flown at volcan villarrica chile we compare uas derived gas timeseries to simultaneous crater rim multi gas data and uv camera imagery to investigate early plume evolution so2 concentrations measured in the young proximal plume exhibit periodic variations that are well correlated with the concentrations of other species by combining molar gas ratios co2 so2 1 48 1 68 h2o so2 67 75 and h2o co2 45 51 with the so2 flux 142 17 t day from uv camera images we derive co2 and h2o fluxes of 150 t day and 2850 t day respectively we observe good agreement between time averaged molar gas ratios obtained from simultaneous uas and ground based multi gas acquisitions however the uas measurements made in the young less diluted plume reveal additional short term periodic structure that reflects active degassing through discrete audible gas exhalations

the structure dynamics and chemical composition of noneruptive plumes from mount st helens 1980 1988 abstract from may 1980 to september 1988 more than 1000 fixed wing aircraft flights were made with a correlation spectrometer to measure the sulfur dioxide flux from mount st helens volcano these flights also provided valuable data on the structure and dynamics of noneruptive plumes emanating from mount st helens during 1980 and part of 1981 an infrared spectrometer was also used to measure carbon dioxide emission rates at distances up to 25 km from mount st helens plume widths can range up to 20 km or more with width thickness ratios from 3 to about 30 maximum sulfur dioxide concentrations in these plumes depend on wind speed and are typically under 5 ppm and usually 1 ppm or less close examination of the plume data reveals that the characteristics of quiescent plumes from mount st helens are strongly affected by certain meteorological conditions such as thermal and wind stratification in the troposphere as well as by the topography of the volcano

determining the three dimensional structure of a volcanic plume using unoccupied aerial system uas imagery abstract this study presents a photogrammetric method for 3d reconstruction of a volcanic plume outline to retrieve its spatial properties a dataset of sequential multi view images was collected using a drone mounted camera for a small scale volcanic plume emitted from volcan pacaya guatemala a space carving algorithm has been applied to estimate the plume shape top height volume and drift direction the complete method workflow is presented herein including data capture camera projection image segmentation and model reconstruction the process applied is considered the simplest approach to reconstruct a 3d plume model from sequential imagery whilst accounting for scene evolution within a probabilistic framework the algorithm is sensitive to the method of image segmentation scene resolution and number of images used with unquantifiable uncertainty in the estimated plume volume due to the lack of ground truth data this proof of concept investigation confirms that 3d quantification of volcanic plume geometry can be achieved using uas based photogrammetry and shows promising results for a new method of measuring volcanic source parameters to validate and adjust dispersion models of volcanic plumes

airborne measurements of volcanic gas composition during unrest at kuchinoerabujima volcano japan airborne measurements of volcanic gas composition using an unmanned aerial vehicle uav and cessna aircraft were conducted at kuchinoerabujima volcano japan between 2014 and 2016 because eruptions occurred in august 2014 may 2015 and june 2015 access to the summit crater was limited because of the risk of sudden eruption such that airborne measurements were the only viable method to measure the volcanic gas composition multi gas and alkali filter pack measurements were made on the leeward side of the crater and around the crater using the cessna and uav respectively observations using the uav could measure the dense plume and quantify the gas species of h2o co2 so2 h2s h2 hcl and hf while the observations using the cessna could measure only the diluted plume and quantify co2 so2 h2s and h2 the seven airborne observations enabled us to monitor variations in the volcanic gas composition over the observation period the so2 h2s ratio decreased from 10 to 1 9 the h2o so2 ratio h2 so2 ratio and apparent equilibrium temperatures aet estimated using the volcanic gas composition increased after the 2014 eruption the decrease in the so2 h2s ratio might be attributed to changes in the pressure of degassing magma and interactions with the hydrothermal system the airborne methods presented here highlight the utility of using light aircrafts to safely conduct volcanic gas measurements during periods of volcanic unrest when traditional ground based methods are not possible

balloon borne measurement of the aerosol size distribution from an icelandic flood basalt eruption we present in situ balloon borne measurements of aerosols in a volcanic plume made during the holuhraun eruption iceland in january 2015 the balloon flight intercepted a young plume at 8 km distance downwind from the crater where the plume is 15 min of age the balloon carried a novel miniature optical particle counter loac light optical aerosol counter which measures particle number concentration and size distribution in the plume alongside a meteorological payload we discuss the possibility of calculating particle flux by combining loac data with measurements of sulfur dioxide flux by ground based uv spectrometer doas the balloon passed through the plume at altitude range of 2 0 3 1 km above sea level a s l the plume top height was determined as 2 7 3 1 km a s l which is in good agreement with data from infrared atmospheric sounding interferometer iasi satellite two distinct plume layers were detected a non condensed lower layer 300 m thickness and a condensed upper layer 800 m thickness the lower layer was characterized by a lognormal size distribution of fine particles 0 2 m diameter and a secondary coarser mode 2 3 m diameter with a total particle number concentration of around 100 cm 3 in the 0 2 100 m detection range the upper layer was dominated by particle centered on 20 m in diameter as well as containing a finer mode 2 m diameter the total particle number concentration in the upper plume layer was an order of magnitude higher than in the lower layer we demonstrate that intercepting a volcanic plume with a meteorological balloon carrying loac is an efficient method to characterize volcanic aerosol properties during future volcanic eruptions balloon borne measurements could be carried out easily and rapidly over a large spatial area in order to better characterize the evolution of the particle size distribution and particle number concentrations in a volcanic plume

new geochemical insights into volcanic degassing magma degassing plays a fundamental role in controlling the style of volcanic eruptions whether a volcanic eruption is explosive or effusive is of crucial importance to approximately 500 million people living in the shadow of hazardous volcanoes worldwide studies of how gases exsolve and separate from magma prior to and during eruptions have been given new impetus by the emergence of more accurate and automated methods to measure volatile species both as volcanic gases and dissolved in the glasses of erupted products the composition of volcanic gases is dependent on a number of factors the most important being magma composition and the depth of gas melt segregation prior to eruption this latter parameter has proved difficult to constrain in the past yet is arguably the most critical for controlling eruptive style spectroscopic techniques operating in the infrared have proved to be of great value in measuring the composition of gases at high temporal resolution such methods when used in tandem with microanalytical geochemical investigations of erupted products are leading to better constraints on the depth at which gases are generated and separated from magma a number of recent studies have focused on transitions between explosive and effusive activity and have led to a better understanding of gas melt segregation at basaltic volcanoes other studies have focused on degassing during intermediate and silicic eruptions important new results include the recognition of fluxing by deep derived gases which buffer the amount of dissolved volatiles in the melt at shallow depths and the observation of gas flow up permeable conduit wall shear zones which may be the primary mechanism for gas loss at the cusp of the most explosive and unpredictable volcanic eruptions in this paper i review current and future directions in the field of geochemical studies of volcanic degassing processes and illustrate how the new insights are beginning to change the way in which we understand and classify volcanic eruptions

electrochemical sensing of volcanic gases we report here the development and application of a compact geochemical nose incorporating electrochemical sensors for gas measurements in volcanic plumes a novel element of the instrument design is the arrangement of the sensors in a parallel array that enables near simultaneous exposure and fast response data analysis methods were developed that utilise the multi sensor output currents to extract gas mixing ratio abundances and eliminate cross sensitivities use of filter methods is demonstrated to remove baseline drift or instrument noise we introduce a new approach for analysis of measurements from sensors that have a slower response time e g hcl and apply this model to estimate hcl so2 ratios we deployed the sensor system at aso volcano japan detecting emissions from its fumarole field hot crater lake and a mixed plume we measured so2 h2s co and hcl ranging in abundance from 102 104 ppbv neither no2 nor cl2 were detected for the fumarolic gases molar ratios were measured as follows h2s so2 is 0 15 h2 so2 0 25 co so2 0 02 hcl so2 0 1 the crater lake plume s h2s so2 is 0 03 the compositions are discussed in terms of degassing equilibria and plume chemistry our instrument design represents a cost effective low power and highly portable system that can be readily adapted for operational surveillance of volcanic gases

review of the evolution of geochemical monitoring networks and methodologies applied to the volcanoes of the aeolian arc italy abstract fluids discharged from volcanic systems are the direct surface manifestation of magma degassing at depth and provide primary insights for evaluating the state of volcanic activity we review the geochemical best practice in volcanic surveillance based to a huge amount of monitoring data collected at different active volcanoes using both continuous and discontinuous approaches the targeted volcanoes belong to the aeolian arc located in the tyrrhenian sea italy and they have exhibited different activity states during the monitoring activities reported here la fossa cone on vulcano island has been in an uninterrupted quiescent stage characterized by variable solfataric activity in contrast stromboli island has shown a persistent mild explosive activity episodically interrupted by effusive eruptions in 1985 2002 2007 and 2014 panarea island which is the summit of a seamount rising from the seafloor of the southern tyrrhenian sea showed only undersea fluid release the only observable clues of active volcanism at panarea island have been impulsive changes in the undersea fluid release with the last submarine gas burst event being observed in november 2002 the geochemical monitoring and observations at each of these volcanoes has directly involved the volcanic plume and or the fumarole vents thermal waters and diffuse soil degassing depending on the type of manifestations and the level of activity encountered through direct access to the magmatic samples when possible and the collection of as much observable data related to the fluid release as possible the aim has been i to verify the thermodynamic equilibrium condition ii to discern among the possible hydrothermal magmatic marine and meteoric sources in the fluid mixtures iii to develop models of the fluid circulation supported by data iv to follow the evolution of these natural systems by long term monitoring and v to support surveillance actions related to defining the volcanic risk and the evaluation and possible mitigation of related hazards the examples provided in this review article show the close relationships among data analysis interpretation and modeling we particularly focus on describing the fieldwork procedures since any theoretical approach must always be verified and supported by field data rather than just by experiments controlled in laboratory indeed the natural systems involve many variables producing effects that cannot be neglected the monitored volcanic systems have been regarded as natural laboratories and all of the activities have focused on both volcanological research and surveillance purposes in order to ensure that these two goals have overlapped an appendix is also included that explains the scientific approach to the systematic activities regarding geochemical monitoring of volcanic activity

accurately measuring volcanic plume velocity with multiple uv spectrometers a fundamental problem with all ground based remotely sensed measurements of volcanic gas flux is the difficulty in accurately measuring the velocity of the gas plume since a representative wind speed and direction are used as proxies for the actual plume velocity there can be considerable uncertainty in reported gas flux values here we present a method that uses at least two time synchronized simultaneously recording uv spectrometers flyspecs placed a known distance apart by analyzing the time varying structure of so2 concentration signals at each instrument the plume velocity can accurately be determined experiments were conducted on k lauea usa and masaya nicaragua volcanoes in march and august 2003 at plume velocities between 1 and 10 m s 1 concurrent ground based anemometer measurements differed from flyspec measured plume speeds by up to 320 this multi spectrometer method allows for the accurate remote measurement of plume velocity and can therefore greatly improve the precision of volcanic or industrial gas flux measurements

co2 output discharged from stromboli island italy abstract total co 2 output from soil gas and plume discharged from the stromboli island was estimated the co 2 emission of the plume emitted from the active crater was estimated on the basis of the so 2 crater output and c s ratio while co 2 discharged through diffuse soil emission was quantified on the basis of 419 measurements of co 2 fluxes from the soil of the whole island performed by using the accumulation chamber method the results indicate an overall output of 416 t day 1 of co 2 from the island the main contribution to the total co 2 output comes from the summit area 396 t day 1 with 370 t day from the active crater and 26 t day 1 from the pizzo sopra la fossa soil degassing area the release of co 2 from peripheral areas is 20 t day 1 by soil degassing scari area mainly the result of the soil degassing survey confirms the persistence of the highest co 2 degassing areas located on the north east crater side and scari area

collecting field data in volcanic landscapes using small uas suas drones abstract the last several years have seen a very rapid increase in the development and availability of unmanned aerial vehicles systems uav or uas more commonly called drones uas are remotely operated aerial vehicles that can be fixed wing planes helicopters or aerial systems with multiple propellers small versions of uas here called suas in particular have become so prevalent that they can be easily purchased at general retail stores this paper seeks to review and summarize the use of suas in volcanic research given their size low cost and relative durability suas provide a light weight tool platform that is easy to transport to field locations quick to set up and easy to launch and control they require very little launch and recovery space because of these characteristics suas are useful in collecting immediate and real time aerial data especially in remote inaccessible dynamic and or hazardous volcanic environments in volcanic areas suas have been used for mapping sample collection thermal imaging magnetic surveys slope stability studies and as platforms for sensors to measure outgassing of co 2 and so 2 they are also becoming invaluable for real time hazard assessment during and after an eruption they are however limited by their flight time which is greatly affected by wind speeds since they are predominately made of plastic they are also impacted by the high thermal temperatures found in active volcanic areas which can degrade their structure and performance with continued technological improvement however suas have the potential to dramatically improve our ability to collect field data because of additional natural technological and legal challenges related to their use it is critical that users be aware of and adhere to all national and local laws associated with suas

uv camera measurements of fumarole field degassing la fossa crater vulcano island abstract the uv camera is becoming an important new tool in the armory of volcano geochemists to derive high time resolution so2 flux measurements furthermore the high camera spatial resolution is particularly useful for exploring multiple source so2 gas emissions for instance the composite fumarolic systems topping most quiescent volcanoes here we report on the first so2 flux measurements from individual fumaroles of the fumarolic field of la fossa crater vulcano island aeolian island which we performed using a uv camera in two field campaigns in november 12 2009 and february 4 2010 we derived 0 5 hz so2 flux time series finding fluxes from individual fumaroles ranging from 2 to 8 7 t d 1 with a total emission from the entire system of 20 t d 1 and 13 t d 1 in november 2009 and february 2010 respectively these data were augmented with molar h2s so2 co2 so2 and h2o so2 ratios measured using a portable multigas analyzer for the individual fumaroles using the so2 flux data in tandem with the molar ratios we calculated the flux of volcanic species from individual fumaroles and the crater as a whole co2 684 t d 1 and 293 t d 1 h2s 8 t d 1 and 7 5 t d 1 and h2o 580 t d 1 and 225 t d 1

phase equilibria constraints on relations of ore bearing intrusions with flood basalts in the noril sk region russia phase equilibria analysis has been performed to elucidate whether ore bearing noril sk and poorly mineralized lower talnakh type intrusions are co magmatic with the extremely ni cu and pges depleted and not depleted flood basalts respectively the parental magma of the intrusions is classified as silica undersaturated olivine basalt whereas that of the flood basalts is assigned to silica saturated tholeiite the plutonic equivalent of the former parental magma is olivine gabbro or melagabbro whereas the latter is gabbronorite phase equilibria relations clearly show that these two types of magmas cannot be co magmatic as there is no way to derive one liquid from another by fractional crystallization this provides no support for the current model considering the noril sk type intrusions as exit conduits for a great volume of volcanic magma which lost most of its chalcophile elements in the shallow settling chambers on its way to surface the association of a large volume of chalcophile element depleted basalts with the very sulfide rich intrusions in the noril sk region is most likely coincidental and cannot therefore be used as a regional criterion when prospecting for the noril sk type sulfides deposits in other flood basalts provinces

carbon dioxide degassing by advective flow from usu volcano japan magmatic carbon dioxide co2 degassing has been documented before the 31 march 2000 eruption of usu volcano hokkaido japan six months before the eruption an increase in co2 flux was detected on the summit caldera from 120 september 1998 to 340 metric tons per day september 1999 followed by a sudden decrease to 39 metric tons per day in june 2000 3 months after the eruption the change in co2 flux and seismic observations suggests that before the eruption advective processes controlled gas migration toward the surface the decrease in flux after the eruption at the summit caldera could be due to a rapid release of co2 during the eruption from ascending dacitic dikes spreading away from the magma chamber beneath the caldera

droplets and bubbles solidification of sulphide rich vapour saturated orthocumulates in the norilsk talnakh ni cu pge ore bearing intrusions

morphological and structural changes at the merapi lava dome monitored in 2012 15 using unmanned aerial vehicles uavs abstract dome building volcanoes undergo rapid and profound topographic changes that are important to quantify for the purposes of hazard assessment however as hazardous lava domes often develop on high altitude volcanoes that exhibit steep sided topography it is challenging to obtain direct field access and thus to analyze these morphological and structural changes merapi volcano in indonesia is a type example of such a volcano as soon after its 2010 eruption a new lava dome developed this dome was partially destroyed during six distinct steam driven explosions that occurred between 2012 and 2014 here we investigate the topographic and structural changes associated with these six steam driven explosions by comparing close range photogrammetric data obtained before and after these explosions to accomplish this we performed two uav campaigns in 2012 and 2015 by applying the structure from motion sfm technique we are able to construct three dimensional point clouds assess their quality by comparing them to a terrestrial laser scanning tls dataset and generate high resolution digital elevation models dems and photomosaics the comparison of these two dems and photomosaics reveals changes in topography and the appearance of fractures in the 2012 dataset we find a dense fracture network striking to the nnw sse in the post eruptive 2015 dataset we see that this nnw sse fracture trend is much more strongly expressed we also detect the formation of aligned and elongated explosion craters which are associated with the removal of over 200 000 m3 of dome material most of which 70 was deposited outside the crater region therefore this study suggests that the locations of the steam driven explosions at merapi volcano were controlled by the reactivation of preexisting structures moreover some of the newly developed and reactivated fractures delineate a block on the southern slope of the dome which could become structurally unstable and potentially lead to rock avalanche hazards this study therefore demonstrates the significance of characterizing structural fingerprints during the development of lava domes and exemplifies the value of topographic and fracture mapping which is becoming increasingly feasible when using uavs even on high and steep stratovolcanoes

volatile emissions from the crater and flank of oldoinyo lengai volcano tanzania as a comparison to airborne infrared ir flux measurements ground based sampling of fumarole and soil gases was used to characterize the quiescent degassing of co2 from oldoinyo lengai volcano aerial and ground based measurements are in good agreement 75 of the aerially measured co2 flux at lengai 0 05 0 06 1012 mol yr 1 or 6000 7200 tonnes co2 d 1 can be attributed to seven large crater vents in contrast to etna and vulcano island where 15 50 of the total co2 flux emanates diffusely through the volcanic flanks diffuse emissions were measured only within 500 m of the crater rim at lengai contributing 2 of the total flux the lack of extensive flank emissions may reflect the dimensions of the magma chamber and or the lack of a shallow fluid flow system thermodynamic restoration of fumarole analyses shows that gases are the most co2 rich and h2o poor reported for any volcano containing 64 74 co2 24 34 h2o 0 88 1 0 h2 0 1 0 4 co and 0 1 h2s hcl hf and ch4 volatile emissions of s cl and f at oldoiyno lengai are estimated as 4 5 1 5 and 1 0 107 mol yr 1 respectively accuracy of the airborne technique was also assessed by measuring the c emission rate from a coal burning power plant co2 fluxes were measured within 10 near the plant however poor resolution at increased distances caused an underestimation of the flux by a factor of 2 the relatively large co2 fluxes measured for alkaline volcanoes such as oldoinyo lengai or etna may indicate that midplate volcanoes represent a large yet relatively unknown natural source of co2

computed tomography reconstruction of so2 concentration distribution in the volcanic plume of miyakejima japan by airborne traverse technique using three uv spectrometers 1 we present here a new method for measuring the so2 concentration distribution in a volcanic plume cross section by using the airborne traverse technique with three uv spectrometers and calculating a computed tomography ct reconstruction our observation requires only one traverse and is as easy as conventional measurements of so2 flux the plume is traverse scanned using three uv spectrometers aligned at three different zenith angles and a ct technique initially designed for air pollutant monitoring was improved by using akaike s bayesian information criterion abic we applied this method to a volcanic plume at 10 km downwind from the caldera of miyakejima volcano in aug 2004 the results of the application show that the profile of the plumes significantly changed in only a matter of a few minutes due to the flexibility and ease of the observation procedure this method is widely applicable to various fields and shows promise in volcanic gas monitoring

alteration characteristics of granite contact zone and treatment measures for inrush hazards during tunnel construction a case study abstract several large scale mud and water inrush events occurred during excavation of the denghuazhai tunnel at a depth of 175 m in the contact zone between geodic granite and tuff by analyzing the inrush process the characteristics of the inrush hazards such as high pressure abundant water high mud and sand content and strong destructive power were revealed in addition the inrush hazards were intermittent uncertain and sudden an intrusive contact zone between geodic granite and tuff was revealed by regional geological investigation large scale alteration occurred both in geodic granite and tuff near the contact zone petrographic analyses indicated that alteration to albite sericite and kaolinite occurred in geodic granite and alteration to quartz and montmorillonite took place in tuff gradually toward the contact zone furthermore the changes were gradational within and between various alteration grades the closer to the contact zone the higher degree of alteration the less the primary minerals including quartz k feldspar and plagioclase the more the secondary minerals such as sericite and clay minerals tests on porosity saturated water content and uniaxial compressive strength indicated that alteration led to significant deterioration of physical and mechanical properties of rocks except for silicified tuff especially for the zonal clay in the central area of contact zone the physical and mechanical properties were poor and obvious swelling disintegration and argillation were observed tunnel excavation triggered swelling disintegration and argillation of clay leading to several large scale inrush events in terms of treatment of inrush hazards first of all a comprehensive exploration method based on petrographic analyses geophysical detection and borehole drilling was established according to the alteration characteristics so as to identify the scale and composition of the altered zone the principle of consolidation before removal was adopted to deal with the inrush deposits for breach sealing and reinforcement energy release and stress reduction during tunnel construction and regular drainage during operation were achieved by dewatering measures namely drainage supplemented by sealing water drainage and solids remaining reinforcement measures including full face curtain grouting and double layer pipe sheds were adopted to reinforce and seal the highly disturbed rock and soil in advance finally technical measures including bench excavation enhancement of support stiffness and timely installation of secondary support were employed to effectively prevent large deformation in disturbed rock masses with the above measures the left and right tunnels of the denghuozhai tunnel have passed through the altered zone successfully

constraining the sulfur dioxide degassing flux from turrialba volcano costa rica using unmanned aerial system measurements abstract observed sulfur dioxide so 2 mixing ratios onboard unmanned aerial systems uas during march 11 13 2013 are used to constrain the three day averaged so 2 degassing flux from turrialba volcano within a bayesian inverse modeling framework a mesoscale model coupled with lagrangian stochastic particle backward trajectories is used to quantify the source receptor relationships at very high spatial resolutions i e 2 variations when using a first order closure non local planetary boundary layer pbl scheme the optimized so 2 degassing fluxes vary from 0 59 0 37 to 0 83 0 33 kt d 1 depending on the pbl scheme used these fluxes are in good agreement with ground based gas flux measurements and correspond to corrective scale factors of 8 12 to the posteruptive so 2 degassing rate in the aerocom emission inventory the maximum a posteriori solution for the so 2 flux is highly sensitive to the specification of prior and observational errors and relatively insensitive to the so 2 loss term and temporal averaging of observations our results indicate relatively low degassing activity but sustained sulfur emissions from turrialba volcano to the troposphere during march 2013 this study demonstrates the utility of low cost small uas platforms for volcanic gas composition and flux analysis

measurement of volcanic so2 fluxes with differential optical absorption spectroscopy abstract measurements of volcanic sulphur dioxide fluxes are important indicators of volcanic activity and are crucial to understanding the impacts of volcanic emissions upon the environment and climate for more than thirty years correlation spectrometers cospecs have provided valuable service in this respect however given the vintage and operational costs of these devices research groups and volcano observatories have recently begun using state of the art lightweight compact and inexpensive usb2000 ultraviolet spectrometers as a replacement technology with differential absorption spectroscopy so2 concentration retrievals in order to widen the dissemination of the latter approach an overview of this methodology is given here covering hardware protocols and the use of freely available software written for this purpose

electrochemical sensors applied to pollution monitoring measurement error and gas ratio bias a volcano plume case study there is an increasing scientific interest in the use of miniature electrochemical sensors to detect and quantify atmospheric trace gases this has led to the development of multi gas systems applied to measurements of both volcanic gas emissions and urban air pollution however such measurements are subject to uncertainties introduced by sensor response time a critical issue that has received limited attention to date here a detailed analysis of output from an electrochemical so2 sensor and two h2s sensors contrasting in their time responses and cross sensitivities demonstrates how instrument errors arise under the conditions of rapidly fluctuating by dilution gas abundances leading to scatter and importantly bias in the reported gas ratios in a case study at miyakejima volcano japan electrochemical sensors were deployed at both the crater rim and downwind locations thereby exposed to rapidly fluctuating and smoothly varying plume gas concentrations respectively discrepancies in the h2s so2 gas mixing ratios derived from these measurements are attributed to the sensors differing time responses to so2 and h2s under fluctuating plume conditions with errors magnified by the need to correct for so2 interference in the h2s readings development of a sensor response model that reproduces sensor t90 behaviour the time required to reach 90 of the final signal following a step change in gas abundance during calibration enabled this measurement error to be simulated numerically the sensor response times were characterised as so2 sensor t90 13 s h2s sensor without interference t90 11 s and h2s sensor with interference t90 20 s to h2s and 32 s to so2 we show that a method involving data integration between periods of episodic plume exposure identifiable in the sensor output yields a less biased h2s so2 ratio estimate than that derived from standard analysis approaches for the miyakejima crater rim dataset this method yields highly correlated h2s and so2 abundances r2 0 99 and the improved crater rim data analysis combined with downwind measurements yields h2s so2 0 11 0 01 our analysis has significant implications for the reliance that can be placed on multi gas derived gas ratios whether for volcanological or other purposes in the absence of consideration of the complexities of sensor response times

unmanned aerial vehicle measurements of volcanic carbon dioxide fluxes i we report the first measurements of volcanic gases with an unmanned aerial vehicle uav the data were collected at la fossa crater vulcano italy during april 2007 with a helicopter uav of 3 kg payload carrying an ultraviolet spectrometer for remotely sensing the so 2 flux 8 5 mg d 1 and an infrared spectrometer and electrochemical sensor assembly for measuring the plume co 2 so 2 ratio by multiplying these data we compute a co 2 flux of 170 mg d 1 given the deeper exsolution of carbon dioxide from magma and its lower solubility in hydro thermal systems relative to so 2 the ability to remotely measure co 2 fluxes is significant with promise to provide more profound geochemical insights and earlier eruption forecasts than possible with so 2 fluxes alone the most ubiquitous current source of remotely sensed volcanic gas data

drone with thermal infrared camera provides high resolution georeferenced imagery of the waikite geothermal area new zealand abstract drones are now routinely used for collecting aerial imagery and creating digital elevation models dem lightweight thermal sensors provide another payload option for generation of very high resolution aerial thermal orthophotos this technology allows for the rapid and safe survey of thermal areas often present in inaccessible or dangerous terrain here we present a 2 2 km 2 georeferenced temperature calibrated thermal orthophoto of the waikite geothermal area new zealand the image represents a mosaic of nearly 6000 thermal images captured by drone over a period of about 2 weeks this is thought by the authors to be the first such image published of a significant geothermal area produced by a drone equipped with a thermal camera temperature calibration of the image allowed calculation of heat loss 43 12 mw from thermal lakes and streams in the survey area loss from evaporation conduction and radiation an rgb visible spectrum orthomosaic photo and digital elevation model was also produced for this area with ground resolution and horizontal position error comparable to commercially produced lidar and aerial imagery obtained from crewed aircraft our results show that thermal imagery collected by drones has the potential to become a key tool in geothermal science including geological geochemical and geophysical surveys environmental baseline and monitoring studies geotechnical studies and civil works