soil radon and elemental mercury distribution and relation to magmatic resurgence at long valley caldera the response of a large geothermal system to magmatic resurgence was analyzed by a survey of soil gas radon and elemental mercury at 600 sites in the silicic long valley caldera california the broad geochemical anomaly over the caldera has superimposed on it a small zone of pronounced radon enrichment and mercury depletion coincident with the surface projection of a postulated dike of rising magma soil gas geochemistry studies can complement traditional geophysical and geodetical methods in the evaluation of potential volcanic eruption hazards

fault location by radon and mercury detection at an active volcano in nicaragua the masaya caldera complex nicaragua with the active crater santiago fig 1 is the site of present day basaltic volcanism1 2 some of the faults that bound the caldera and lie within it can be located geologically others are postulated a possible older caldera rim lies to the south of the present margin to investigate whether one can identify faults in this environment of active volcanism concentrations of radon and mercury in the regolith were determined at 232 selected points in and adjacent to the caldera higher concentrations of hg0 or rn or both occurred over 75 of the known structures studied some hitherto suspected structures were confirmed while others were not lack of a chemical signature may be ascribed to the absence of a structure inappropriate sampling sites post fault lava cover or other sealing of the structure we show here how the use of rn and hg0 determinations has helped in structural analysis at this active volcano

outburst floods from glacial lake missoula abstract the pleistocene outburst floods from glacial lake missoula known as the spokane floods released as much as 2184 km3 of water and produced the greatest known floods of the geologic past a computer simulation model for these floods that is based on physical equations governing the enlargement by water flow of the tunnel penetrating the ice dam is described the predicted maximum flood discharge lies in the range 2 74 106 13 7 106 m3 sec 1 lending independent glaciological support to paleohydrologic estimates of maximum discharge

radon surveys and real time monitoring at stromboli volcano influence of soil temperature atmospheric pressure and tidal forces on 222rn degassing abstract we used a network of stations to perform systematic radon surveys at stromboli volcano the time series of periodic measurements show that monthly average 222rn emissions reflect changes in volcanic activity and exhibit increasing trends prior and during the last major eruptive cycles maps of radon emissions indicate that diffuse degassing is operative at stromboli volcano concentrated degassing essentially occurs in the summit area and within a sector proximal to the two major ne trending faults these sites were chosen for deploying the two real time stations that are currently operating at stromboli in these devices the 222rn electronic dosimeters are connected to a radiomodem for wireless data transfer to a receiving station at the volcano observatory radon activity soil temperature and atmospheric pressure data are sampled and instantaneously transferred via web so that they can be checked remotely collected time series reveal an overall inverse correlation between radon emissions and seasonal temperature variations radon emissions in sectors of diffuse degassing are modulated by tidal forces as well radon activities recorded at the summit station located along the fracture zone where the gas flux is concentrated are positively correlated with changes in atmospheric pressure and confirm the occurrence of the atmospheric stack effect we finally emphasize that real time radon monitoring is an innovative technique that may be systematically applied in volcano surveillance

insights into fluid circulation across the pernicana fault mt etna italy and implications for flank instability article i nfo we conducted geophysical geochemical measurements on a 2k m n s profile cutting across the pernicana fault one of the most active tectonic features on the ne flank of mt etna the profile passes from the unstable e flank of the volcano to the south to the stable n flank and significant fluctuations in electrical resistivity self potential and soil gas emissions co2 rn and th are found the detailed multidisciplinary analysis reveals a complex interplay between the structural setting uprising hydrothermal fluids meteoric fluids percolating downwards ground permeability and surface topography in particular the recovered fluid circulation model highlights that the southern sector is heavily fractured and faulted allowing the formation of convective hydrothermal cells although the existence of a hydrothermal system in a volcanic area does not surprise these results have great implications in terms of flank dynamics at mt etna indeed the hydrothermal activity interacting with the pernicana fault activity could enhance the flank instability our approach should be further extended along the full extent of the boundary between the stable and unstable sectors of etna for a better evaluation of the geohazard in this active tectonic area

soil222rn pulse during the initial phase of the june august 1995 eruption of cerro negro nicaragua the june august 1995 eruption of cerro negro a small volume basaltic cinder cone in nicaragua provided a unique opportunity to quantify 222rn degassing from soils in response to explosive volcanic activity 222rn was monitored at 29 stations using electrostatically charged teflon 222rn detectors distributed north and southeast of the volcano a pulse of elevated 222rn degassing occurred early in the eruption along a 1 km long zone extending at least 750 m beyond the base of the cinder cone observation of this 222rn pulse shows that large changes in soil 222rn concentration can occur simultaneously at widely separated stations in response to even comparatively small volume intrusions and volcanic eruptions frequent 222rn sampling at multiple stations provides a sense of the magnitude time scales and area affected by convective gas transport during volcanic eruptions

the degassing character of a young volcanic center cerro negro nicaragua cerro negro volcano is a young basaltic cinder cone which is part of the nicaraguan volcanic arc eruptive activity at cerro negro is characterized by explosive strombolian to subplinian eruptions driven by volatile rich basaltic magma ascending rapidly from various crustal depths 15 to 6 km resulting in the onset of precursory activity only 30 min before an eruption in this paper we present a comprehensive degassing characterization of the volcano over a 4 year period aimed at improving our understanding of the magmatic plumbing network and its relationship with regional tectonics a total of 124 individual soil gas samples were collected between 2010 and 2013 and analyzed for stable carbon isotopes 13c from co2 high temperature fumaroles were sampled for 18o d and 3he 4he isotope analysis and major degassing zones were mapped using soil co2 flux measurements gases at cerro negro are characterized by a strong 3he 4he mantle signature 6 3 to 7 3 ra magmatic 13c ratios 2 3 to 3 0 meteoric 18o and d ratios and stable co2 fluxes 31 t d 1 the lack of 13c fractionation and an increase in the relative mantle component from 2002 to 2012 suggest that the volatile flux at cerro negro originates from the mantle and ascends to the surface via a series of crustal fractures that act as permeable conduits despite the lack of new eruptions the hydrothermal system of cerro negro continues to evolve due to seasonal inputs of meteoric water slope failures that expose and bury sites of active degassing and bursts of regional seismicity that have the potential to open up new conduits for gas release as well as magma continuing geophysical and geochemical monitoring of the main edifice and the recently formed south zone is essential as the volcano remains overdue to erupt

comparative analysis of continuous radon sensors in underground environments four different continuous radon 222rn detection systems have been compared in underground environments namely three subhorizontal tunnels excavated for groundwater exploitation within observational uncertainties all sensors detected the same concentrations of radon in the air of the tunnels regardless of the methodology used to measure this radioactive gas in this sense the choice of continuous long term radon monitoring sensors in underground tunnels is constrained by factors such as robustness of the instrumentation power supply and cost rather than the sensitivity of the detection methodology this is particularly important for the monitoring of radon in the context of seismo volcanic surveillance where the harsh environmental conditions of the monitoring sites and the absence of electrical power supply are key factors to take into account

high co2 levels in boreholes at el teide volcano complex tenerife canary islands implications for volcanic activity monitoring emissions of co2 have been known for more than a hundred years as fumarolic activity at the terminal crater of el teide volcano and as diffuse emissions at numerous water prospection drillings in the volcanic island of tenerife large concentrations of co2 10 in volume have been found inside galleries long horizontal tunnels excavated for water mining however co2 concentrations of only 2900 ppm have been observed at the surface of the central region of the island las canadas del teide caldera in this work we analysed co2 concentrations in the subsurface of las canadas caldera in an attempt to study the vertical distribution of carbon dioxide and in particular the low emissions at the surface this has been done through a series of 17 vertical profiles in two deep boreholes excavated in the caldera we found high levels of co2 varying in time from 13 vol up to 40 vol in different profiles directly above the water table while no significant concentrations were detected above the thermal inversion that takes places in both boreholes at approximately 100 m from the water table water analyses also showed high dissolved co2 levels in equilibrium with the air and an average 13c value in dic of 4 7 pdb apparently induced by fast co2 degassing in the bicarbonated water

soil gas radon emissions and volcanic activity at el hierro canary islands the 2011 2012 submarine eruption 1 soil gas radon 222rn and thoron 220rn activities have been continuously measured during the period of the recent volcanic unrest that occurred at el hierro canary islands at two different monitoring stations namely hie02 and hie03 significant increases in soil 222rn activity and 222rn 220rn ratio from the soil were observed at both stations prior to the 2011 2012 submarine eruption off the coast of el hierro showing the highest increases before the eruption onset and before the occurrence of the strongest seismic event m 4 6 statistical analysis showed that the long term temporal trend of filtered radon data matched closely that of seismic energy release during the volcanic unrest the observed increases of 222rn are related to the rock fracturing processes seismic activity and the magmatic co2 outflow increase as observed in hie03 station

changing mercury anomalies in long valley california indication for magma movement or seismic activity mercury anomalies in soils in geothermal areas form as a result of vapor transport comparison of the hg distribution of long valley measured in 1975 and again in 1982 indicates that a new hg anomaly formed in the inyo crater zone in the intervening period two models can explain this new anomaly 1 geothermal water has reached shallow levels as a result of increased permeability created by seismic activity or 2 addition of a co sub 2 rich magnetic vapor to the geothermal system at depth caused vapor exsolution in zones where it did not occur before if the hg anomaly in the inyo crater zone is related to the addition of magmatic vapors the site of the new anomaly may overlie young intruding magma 26 references 5 figures

soil gas emanations as precursory indicators of volcanic eruptions field measurements conducted on several active volcanoes in italy the lesser antilles and indonesia demonstrate the common occurrence of diffuse soil gas emanations from the volcanic piles at distances from active craters or fumarolic zones these emanations consist essentially of carbon dioxide and rare gases and their genetic link with crater fumaroles and or magma degassing at depth can be verified both chemically and isotopically we emphasize here the potential use of these fluids for continuous volcano monitoring and eruption forecasting

radon mapping automatic measurements and extremely high 222rn emissions during the 2002 2007 eruptive scenarios at stromboli volcano abstract we report additional radon data collected at stromboli during 2002 2007 the whole data set of periodic measurements has been systematically analyzed to retrieve the values of background threshold and anomaly for all the stations of the network maps of radon concentrations in space and time correlate with changes in volcanic activity higher radon emissions are essentially concentrated at summit stations and may also affect some stations located onto the summit eastern sector of the cone along the n60 e fracture zone as well as two stations placed at the ne edge of sciara del fuoco most of these stations are well above their threshold values during effusive eruptions namely 2002 2003 and 2007 due to the progressive structural adjustment of the volcano edifice coupled with the opening and resetting of the fracture network a two year long timeseries of automatic 222 rn measurements 2005 2007 was analyzed together with local environmental parameters and selected geophysical data on seismic tremor and infrasonic puffing the data show good correlation between radon and the latter parameters particularly during periods of high strombolian activity march april 2006 and before the onset of the february 27 2007 lava effusion with radon emissions being well above 20 000 bq m 3 extremely high radon emissions up to 1 7 10 6 bq m 3 were recorded along the fractures of the sw crater during the first two months of the 2002 2003 effusive eruption very high radon emissions up to 470 000 bq m 3 for 222 rn and 780 000 bq m 3 for 220 rn respectively were also detected by the automatic measurements at the summit station during june 20 early july 2007 i e just prior to the resuming of the strombolian activity at summit craters these data give us the opportunity to estimate the relative depths of the summit fractures during fracturing being constrained between 200 and 310 m this is in good agreement with the hypocentral depths of the so called hybrid events and the source of the very long period seismic signals vlp localized at a depth of about 500 m a s l below the upper central part of the sciara del fuoco

variations on the concentration of 222rn in the subsurface of the volcanic island of tenerife canary islands 1 a simple theoretical model based on the assumption that radon is transported by molecular diffusion combined with advective flow induced by barometric pressure is used to investigate radon exhalation at three subsurface monitoring sites in the volcanic island of tenerife canary islands the model is intended to filter out all known contributions to radon flux in an attempt to find potential precursory signals of seismic and or volcanic activity for the period of observations 1 december 2000 to 1 april 2001 variations on radon concentration predicted by the model were in good agreement with those measured confirming they were induced by atmospheric pressure changes

controls on acid mine water composition from the iberian pyrite belt sw spain abstract in the iberian pyrite belt ipb especially within the tinto and odiel river basins there is a large number of sources of acid mine drainages amd characterised by very extreme ph conditions and pollution levels this paper studies the main factors governing the composition of the different leachates based on ionic relationships statistically there are no differences between leachates from adits and shafts and other types of amd sources the most extreme conditions ph values near 1 35 g l of fe and 104 mg l of as are found in an area of riotinto covered by milled pyrite wastes used for the production of copper through leaching the cu and zn ore grades deduced from the leachates are in line with the usual values of the ipb which indicate a geological control in the composition of the acid mine waters the lowest so 4 cd and zn cu ratios in the acid leachates are found in the ne of the study area whereas the minimum values of so 4 ni ratios occur in the center and sw this seems to be related with the type of deposit shale hosted at the southern part of the ipb and felsic volcanoclastic hosted at the northern part although there are exceptions to this general pattern likewise the proportions of fe al mg co ni and other elements in the leachates are influenced by the mineralogy and the degree of hydrothermal alteration of each deposit the latter related with co ni ratio

high spatial resolution radon measurements reveal hidden active faults on mt etna radon emissions are frequently monitored in volcanically and tectonically active areas in order to reveal changes in soil degassing as radon acts a tracer for the more abundant co2 degassing commonly observed in such areas between july 2002 and may 2003 a series of discrete measurements of radon concentrations in soil were made with high spatial resolution similar to5 100 m in the santa venerina area on mt etna these measurements revealed well defined linear anomalies that we interpret as being caused by active faults whose higher porosity than surrounding soils allows an increased co2 flux carrying radon from beneath these faults were not visible at the surface and were therefore revealed at high spatial resolution by our radon survey our hypothesis that the positive anomalies are attributable to active faults was strengthened by the observation of concentrated damage along this geometry during the earthquakes that struck this area in late october 2003

runoff control of soil degassing at an active volcano the case of piton de la fournaise reunion island abstract airborne atmospheric and in situ soil gas analyses demonstrate that distal gas leaks are non existent at piton de la fournaise pf despite frequent eruptions airborne traverses made at a constant altitude indicated that no detectable large scale co 2 degassing occurs from the volcano in situ soil gas traverses co 2 4 he 222 rn across the active rift zones the summit crater and the caldera rims show both a lack of positive anomalies and evidence of strong depleted concentrations for he and co 2 with respect to air depletions in soil he is explained by intense rain water infiltration a more unexpected result lies in the very low co 2 concentrations down to 92 ppm in bare soils in the summit region such a depletion was not previously reported and is attributed to considerable basalt weathering operating as the result of huge runoff a model has enabled both the runoff and the co 2 consumption occurring within the basaltic layers to be calculated data obtained are consistent with values expected from large scale erosion models and with the local calculated diffusive flux of co 2 in soils the huge runoff together with the basaltic lithology of the volcano are found to be the main factor controlling the soil gas signatures at pf

origin of fumarolic fluids emitted from a nonerupting volcano radionuclide constraints at vulcano aeolian islands italy the behaviour of 210po and 222rn in hot fumaroles on the crater rim at vulcano island was studied over 12 years 1980 1992 in order to infer the origin of the fluids the decreasing activity of 222rn observed since 1985 results from the mixing of the magmatic component with shallow water a part of 222rn in the gases is emitted by the surrounding rocks and carried along by the shallow water 210po is completely volatilized at t 450 c above this temperature its activity remains unchanged with increasing temperature 210po has two different origins one is magmatic correlated with 222rn the other one is produced by the sublimates deposited in the volcanic edifice from the magmatic 210po component the volume of degassing magma is estimated to be about either 170 000 m3 or 90 000 m3 day according to the model utilized in the first case the associated degassing time is about twelve days