tomography of seismo radio wave source regions for predicting imminent earthquakes abstract to detect a seismo electromagnetic effect in a noisy land area or a deep sea area two methods are proposed in the land area a steel casing pipe inserted in a deep borehole has been used as the linear element of a monopole antenna this method is shown to be very effective in rejecting atmospherics in the deep sea area man made noise and atmospherics can be attenuated by using insulated cables extended along the seabed as a dipole antenna or a loop antenna taking advantage of the seismo radio wave propagating directly through the earth s crust a tomography is proposed to describe a three dimensional intensity distribution of seismo radio wave sources by receiving the wave at four or more points simultaneously to predict precisely an earthquake of magnitude seven or more

the 2009 2010 eruption of gaua volcano vanuatu archipelago eruptive dynamics and unsuspected strong halogens source gaua a little known volcano in the northern part of vanuatu archipelago went through a long term eruptive activity between september 2009 and july 2010 the eruption started by a phreatic to phreatomagmatic activity which progressively shifted into a magmatic discharge the first eruptive phase involved the hydrothermal system in place the latter was likely influenced by seawater seepage leading to the formation of anhydrite magma involved hereafter this opening phase is of basaltic andesite and basaltic trachyandesite composition high k calc alkaline series typical of the northern part of the vanuatu archipelago the 2009 2010 activity discharged at least 184 kt of so2 and a significant amount of halogens 72 kt cl and 217 kt f such halogen releases indicate that gaua is a strong source of halogens into the atmosphere high and sustained amount of f discharges are known to induce health issues and should not be ignored on gaua island during this eruption the quiescent and voluminous lake letas was slightly affected by the eruption nevertheless the hydrothermal discharge point into the lake situated on the southeastern part of mt garet appeared to be relatively active at this particular location rock forming elements leached out from volcanic rock by acid fluids released by the new intrusion of magma were discharged along with anions into lake letas this release has triggered localized chemistry changes in the lake we speculate that this discharge has also disturbed the bottom water in a limited perimeter remobilizing reduced fe to the surface and subsequently triggering the change in the water color by fe oxidation

turbulent heat flux in the upper ocean under sea ice turbulence data from three arctic drift station experiments demonstrate features of turbulent heat transfer in the oceanic boundary layer time series analysis of several w t records shows that heat and momentum flux occur at nearly the same scales typically by turbulent eddies of the order of 10 20 m in horizontal extent and a few meters in vertical extent probability distribution functions of w t have large skewness and kurtosis where the latter confirms that most of the flux occurs in intermittent events with positive and negative excursions an order of magnitude larger than the mean value an estimate of the eddy heat diffusivity in the outer ekman part of the boundary layer based on measured heat flux and temperature gradient during a diurnal tidal cycle over the yermak plateau slope north of fram strait agrees reasonably well with the eddy viscosity with values as high as 0 15 m2 s 1 an analysis of measurements made near the ice ocean interface at the three stations shows that heat flux increases with both temperature elevation above freezing and with friction velocity at the interface it also reveals a surprising uniformity in parameters describing the heat and mass transfer e g the thickness of the transition sublayer from a modified version of the yaglom kader theory is about 10 cm at all three sites despite nearly a fivefold difference in the under ice roughness z0 which ranges from approximately 2 to 9 cm a much simplified model for heat and mass transfer at the ice ocean interface suggested by the relative uniformity of the heat transfer coefficients at the three sites is outlined

southern ocean buoyancy forcing of ocean ventilation and glacial atmospheric co2 ocean circulation and dynamics can alter atmospheric co2 concentrations numerical modelling suggests that shifts in surface buoyancy loss and the location of upwelling can sequester co2 in the southern ocean during glacial periods

the 1995 1998 eruption of the soufriere hills volcano montserrat wi eruption of the soufriere hills volcano began on 18 july 1995 after three years of elevated seismic activity four months of increasingly vigorous phreatic activity culminated in mid november 1995 with the initiation of dome growth growth rates increased unevenly through early march 1996 with fluctuations on time scales from hours to months since march 1996 gravitational collapse of the unstable dome flank has affected an ever increasing area with pyroclastic flows surges and ashfalls major collapse of the eastern flank on 17 september 1996 resulted in a sub plinian explosive eruption later that day by february 1997 the dome had outgrown the confines of the crater and begun to spill into the surrounding valleys a large collapse on 25 june 1997 caused pyroclastic flows and surges on the northern flanks and resulted in the only deaths of the eruption in august september and october 1997 vulcanian explosions followed further collapses on the western and northern flanks the largest event of the eruption occurred on 26 december 1997 with failure of the southwestern flank of the volcano producing a debris avalanche and large dome collapse pyroclastic flows dome growth ceased in early march 1998 but residual volcanic activity has continued and consists of ash venting mild explosions and dome collapse pyroclastic flows

physical and biological regulation of the soft tissue carbon pump 1 we examine the relationship between aeolian iron deposition ocean circulation and atmospheric co2 in the context of a global ocean circulation and biogeochemistry model with a coupled atmospheric reservoir of co2 in common with previous models we find only a small reduction of atmospheric pco2 in response to an enhanced aeolian iron source consistent with last glacial maximum conditions we show this to be due to a combination of limiting factors including control of deep ocean iron concentrations by complexation to an organic ligand regional compensation in changes to export production and the maintenance of high preformed nutrient concentrations in deep water formation regions we also demonstrate a significant sensitivity of atmospheric pco2 to changes in the residual mean overturning circulation of the southern ocean dominated by its regulation of the accumulation of biogenic carbon in the deep ocean although it is not enough to explain the full drawdown of pco2 to glacial levels a reduction in overturning can lead to significant reduction in atmospheric pco2 providing mechanistic basis for the control by vertical mixing inferred from box models

chronology and products of the 2000 eruption of miyakejima volcano japan lateral migration of magma away from miyakejima volcanic island japan generated summit subsidence associated with summit explosions in the summer of 2000 an earthquake swarm beneath miyakejima began on the evening of 26 june 2000 followed by a submarine eruption the next morning strong seismic activity continued under the sea from beneath the coast of miyakejima to a few tens of kilometers northwest of the island summit eruptive event began with subsidence of the summit on 8 july and both explosions and subsidence continued intermittently through july and august the most intense eruptive event occurred on 18 august and was vulcanian to subplinian in type ash lofted into the stratosphere fell over the entire island and abundant volcanic bombs were erupted at this time another large explosion took place on 29 august this generated a low temperature pyroclastic surge which covered a residential area on the northern coast of the island the total volume of tephra erupted was 9 3 106 m3 dre much smaller than the volume of the resulting caldera 6 108 m3 migration of magma away from miyakejima was associated with crustal extension northwest of miyakejima and coincident shrinkage of miyakejima island itself during july august 2000 this magma migration probably caused stoping of roof rock into the magma reservoir generating subsurface cavities filled with hydrothermal fluid and or magmatic foam and formation of a caldera oyama caldera at the summit interaction of hydrothermal fluid with ascending magma drove a series of phreatic to phreatomagmatic eruptions it is likely that new magma was supplied to the reservoir from the bottom during waning stage of magma s migration resulting in explosive discharge on 18 august the 18 august event and phreatic explosions on 29 august produced a conduit system that allowed abundant so2 emission as high as 460 kg s 1 after the major eruptive events were over at the time of writing inhabitants of the island about 3 000 have been evacuated from miyakejima for more than 3 years

streaming potential measurements 1 properties of the electrical double layer from crushed rock samples the potential has been inferred from streaming potential measurements with crushed rock samples as a function of ph and electrolyte concentration for various salts the value obtained for crushed fontainebleau sandstone at ph 5 7 and a kcl solution with a resistivity of 400 m is 40 5 mv where the error is dominated by sample to sample variations the sensitivity of the potential to the electrolyte resistivity for kcl is given experimentally by f 0 23 0 014 where f is the electrolyte resistivity the point of zero charge pzc is observed for ph 2 5 0 1 and the potential is positive for ph pzc for ph 5 the variations of the potential with ph can be approximated by ph 5 7 1 0 068 0 004 ph 5 7 for f 100 m the potential has been observed to be sensitive to the valence of the ions and is approximately reduced by the charge of the cation unless specific adsorption takes place like in the case of al 3 the experimental results are well accounted for by a three layer numerical model of the electrical double layer and the parameters of this model can be evaluated from the experimental data the sensitivity of the potential to the rock minerals has also been studied the potential obtained for granitic rocks is comparable to that obtained for fontainebleau sandstone but can be reduced by a factor of 2 4 for sandstones containing significant fractions of carbonates or clay to take into account the effect of the chemical composition of the electrolyte a chemical efficiency is defined as the ratio of the potential to the potential measured for kcl this chemical efficiency is measured to be 80 for typical groundwater but can be as low as 40 for a water with a high dissolved carbonate content the set of empirical laws derived from our measurements can be used to assess the magnitude of the streaming potentials expected in natural geophysical systems

rainwater and ash leachate analysis as proxies for plume chemistry at soufriere hills volcano montserrat chloride and sulphate concentrations in rainwater and water soluble leachates from volcanic ash samples track the compositions of gas emissions at the soufriere hills volcano montserrat from 1996 to 2001 there are both systematic spatial and temporal variations in the chloride sulphate ratio expressed as the equivalent hcl so2 mass ratio in rainwater and ash leachates temporal variations reflect changes in eruption rate and eruptive style mass ratios of hcl so2 in ash leachates correspond closely with those obtained by open path fourier transform infrared op ftir spectroscopy and reflect changes in volatile emissions throughout the eruption both leachate and op ftir spectroscopic analyses show mass ratios of hcl so2 1 during dome growth and hcl so2 1 during non eruptive periods the hcl so2 mass ratios in rainwater samples from 1996 and 1997 show temporal variations that correlate with changes in extrusion rate the hcl so2 ratios in plume affected rainwater and ash leachates from june and july 2001 correlate positively with increasing rockfall energy and with increasing eruption rate prior to a dome collapse event the hcl so2 mass ratios in water soluble ash leachates and rainwater samples collected at the same time and from the same sites are linearly correlated with rainwater hcl so2 ratios systematically two to three times higher than ash leachate ratios spatial patterns of rainwater ph and hcl so2 in rainwater and ash leachates are principally influenced by the proximity of the sampling sites to the active dome and to the typical pattern of dispersion of the plume by tropospheric winds these results demonstrate that rainwater chemistry and ash leachate analysis provides a useful indicator of volcanic activity and represents a valuable supplement to volcano surveillance efforts

sustaining persistent lava lakes observations from high resolution gas measurements at villarrica volcano chile active lava lakes as the exposed upper part of magmatic columns are prime locations to investigate the conduit flow processes operating at active degassing volcanoes persistent lava lakes require a constant influx of heat to sustain a molten state at the earth s surface several mechanisms have been proposed to explain how such heat transfer can operate efficiently these models make contrasting predictions with respect to the flow dynamics in volcanic conduits and should result in dissimilar volatile emissions at the surface here we look at high frequency so2 fluxes plume composition thermal emissions and aerial video footage from the villarrica lava lake in order to determine the mechanism sustaining its activity we found that while fluctuations are apparent in all datasets none shows a stable periodic behaviour these observations suggest a continuous influx of volatiles and magma to the villarrica lava lake we suggest that ascending volatile rich and descending degassed magmas are efficiently mixed within the volcanic conduit resulting in no clear periodic oscillations in the plume composition and flux we compare our findings to those of other lava lakes where equivalent gas emission time series have been acquired and suggest that gas flux magma viscosity and conduit geometry are key parameters determining which flow mechanism operates in a given volcanic conduit the range of conduit flow regimes inferred from the few studied lava lakes gives a glimpse of the potentially wide spectrum of conduit flow dynamics operating at active volcanoes

glacial ocean circulation and stratification explained by reduced atmospheric temperature earth s climate has undergone dramatic shifts between glacial and interglacial time periods with high latitude temperature changes on the order of 5 10 c these climatic shifts have been associated with major rearrangements in the deep ocean circulation and stratification which have likely played an important role in the observed atmospheric carbon dioxide swings by affecting the partitioning of carbon between the atmosphere and the ocean the mechanisms by which the deep ocean circulation changed however are still unclear and represent a major challenge to our understanding of glacial climates this study shows that various inferred changes in the deep ocean circulation and stratification between glacial and interglacial climates can be interpreted as a direct consequence of atmospheric temperature differences colder atmospheric temperatures lead to increased sea ice cover and formation rate around antarctica the associated enhanced brine rejection leads to a strongly increased deep ocean stratification consistent with high abyssal salinities inferred for the last glacial maximum the increased stratification goes together with a weakening and shoaling of the interhemispheric overturning circulation again consistent with proxy evidence for the last glacial the shallower interhemispheric overturning circulation makes room for slowly moving water of antarctic origin which explains the observed middepth radiocarbon age maximum and may play an important role in ocean carbon storage

air sea disequilibrium of carbon dioxide enhances the biological carbon sequestration in the southern ocean 1 sinking and subduction of organic material removes carbon from the surface ocean and stores it in inorganic form after remineralization the wind driven upwelling of deep waters notably in the southern ocean counteracts the biological carbon sequestration by returning excess carbon from the abyss potentially releasing it back to the atmosphere numerical models have shown that significant fraction of the excess carbon in the antarctic surface water is not degassed to the atmosphere but reenters into the deep ocean due to the incomplete air sea equilibration effectively increasing the efficiency of biological carbon storage in the deep ocean we develop a simple theory to consider the controls on this effect the theory predicts a strong coupling between biological carbon sequestration and air sea disequilibrium expressed as a linear relationship between the biological carbon pump and the degree of supersaturation in the deep ocean sensitivity experiments with a three dimensional ocean biogeochemistry model support this prediction and demonstrate that the disequilibrium pump almost doubles the efficiency of biological carbon sequestration relative to the effect of nutrient utilization

major ion bulk deposition around an active volcano mt etna italy bulk atmospheric deposition of major cations na k ca mg and anions cl f so4 were measured at 15 sites around an active volcano mount etna from 2001 to 2003 their composition indicates several natural sources among which deposition of plume derived volcanogenic gas compounds is prevalent for f cl and s plume derived acidic compounds are also responsible for the prevailing acidic composition of the samples collected on the summit of the volcano ph in the 2 45 5 57 range cation species have complex origin including deposition of plume volcanogenic ash and aerosols and soil dust wind re suspension of either volcanic or carbonate sedimentary rocks

experimental measurement of electromagnetic emissions possibly related to earthquakes in japan recent observations in the ussr appear to suggest that wide band electromagnetic radiation occurs just prior to earthquakes to apply this phenomenon to earthquake prediction measurements have been carried out at the sugadaira space radiowave observatory in japan under the ussr japan cooperation program in 1980 the recorded noise level at 81 khz is comparatively quiet throughout the day and night however about one half hour before the main shock of a magnitude 7 earthquake at 0733 ut on march 31 1980 the instrument recorded an anomalous amplitude increase to 15 db higher than the normal level vlf data recorded synoptically at sugadaira suggest that unusual impulsive radiation at frequencies below 1 5 khz also occurred shortly before the earthquake similar 81 khz emissions were observed prior to magnitude 5 and 6 earthquakes on september 25 1980 and january 28 1981

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

observation of the eruption sequence and formation process of a temporary lava lake during the june august 2015 mt raung eruption indonesia using high resolution and high frequency satellite image datasets abstract from june to august 2015 mt raung located at the east end of java indonesia erupted effusively with strombolian activity at the intra caldera cinder cone the effused lava from the base of the cone entirely buried the caldera floor with a lava bed and ultimately formed a temporary lava lake in this study details of the eruption sequence and formation process of the temporary lava lake are analyzed based on a series of high resolution images combined with the high frequency thermal observation results of himawari 8 the volume of effused lava was also estimated using a digital elevation model aster gdem based on the lava bed bathymetry in the caldera and lava bed distribution at several points over the course of the eruption the total effusion volume was estimated to be 7 5 107 m3 and the average effusion rate was 1 4 106 m3 day the activity consisted of four stages the precursory stage was characterized by low level thermal anomalies which are thought to result from high temperature spots at the bottom of several pits formed in the buried vent probably due to magma head partial exposure or gas emission pulses 1 and 2 were effusive stages that formed the lava bed the pattern recognized in the time series variation of thermal anomalies was confirmed to reflect the lava effusion rate using the volumes estimated in this study the lava bed is divided into the lower and upper lava groups which were generated in pulses 1 and 2 respectively except for the fine lobes formed around the margin of the lower lava group the terminal stage also showed low level thermal anomalies most likely caused by gas emissions the intra caldera cone grew to approximately 100 m higher than its initial height by mid august and then collapsed into the conduit at the end of the terminal stage the lava bed increased in thickness through lobe multi layering and later through the addition of lava directly from the vent into the lava bed interior over the course of the lava bed growth the bed outline nearly matched the caldera contours uplift of the lava bed surface caused lateral fluidization of the bed and molten lava was extruded at the bed margins forming fine lobes this process enlarged the zone of fine lobes around the lava bed thus the lava bed growth resulted in the appearance of a lava lake in the middle of pulse 1 a small amount of hot material was thrown onto the slope beyond the caldera rim in the future the caldera floor uplift caused by this activity approximately 49 m will increase the risk of erupted material ejection outside the caldera in a comparison with the 2013 15 nishinoshima eruption which was a similar effusive eruption mt raung was shown to have predominantly large lobes over most of the lava bed while in nishinoshima narrow medium scale lobes occupied the majority of the surface this may be attributed to the high effusion rate of lava for mt raung which was approximately seven times higher on average than the lava effusion rate for nishinoshima

so2 bro ratios studied in five volcanic plumes abstract the distribution of bromine monoxide bro and sulphur dioxide so2 was measured by ground based max doas scattered light multi axis differential optical absorption spectroscopy in the plume of five volcanoes soufriere hills volcano on montserrat in may 2002 masaya volcano in nicaragua in march 2003 etna volcano on sicily in september october 2003 and august october 2004 stromboli volcano in italy in september 2003 and villarica in chile in november 2004 maximum slant column densities scds of several 1014 molecules cm2 of bro were observed bromine monoxide sulphur dioxide ratios of 10 0 10 4 0 8 10 4 4 8 10 4 2 1 10 4 2 1 10 4 and 1 3 10 4 were found in the plumes of soufriere hills masaya etna 2003 etna 2004 stromboli and villarica respectively causes for the differences in the bro so2 ratios for the various volcanic sites are discussed

antarctic sea ice control on ocean circulation in present and glacial climates in the modern climate the ocean below 2 km is mainly filled by waters sinking into the abyss around antarctica and in the north atlantic paleoproxies indicate that waters of north atlantic origin were instead absent below 2 km at the last glacial maximum resulting in an expansion of the volume occupied by antarctic origin waters in this study we show that this rearrangement of deep water masses is dynamically linked to the expansion of summer sea ice around antarctica a simple theory further suggests that these deep waters only came to the surface under sea ice which insulated them from atmospheric forcing and were weakly mixed with overlying waters thus being able to store carbon for long times this unappreciated link between the expansion of sea ice and the appearance of a voluminous and insulated water mass may help quantify the ocean s role in regulating atmospheric carbon dioxide on glacial interglacial timescales previous studies pointed to many independent changes in ocean physics to account for the observed swings in atmospheric carbon dioxide here it is shown that many of these changes are dynamically linked and therefore must co occur

h2o and halogen f cl br behaviour during shallow magma degassing processes abstract degassing paths of silicic h2o rich magmas during explosive plinian and dome forming eruptions may be represented in simple evolution diagrams relating the residual volatile content of the melt to the volume ratio of gas over melt vg vl these parameters are measurable in erupted magma fragments they are used for interpreting the h2o and halogen contents determined in a series of variously degassed volcanic clasts from the 650 y b p eruption at mt pelee martinique fwi which is characterized by the succession of a dome extrusion and a plinian activity h2o degassing of plinian pumice clasts are modeled by an equilibrium closed system evolution which allows to calculate the partition coefficients of halogen between the aqueous fluid and the rhyolitic melt d v l i 1 for f 10 1 5 for cl and 3 7 1 for br at around 900 c the strong increase of the dv li values of cl and br during dome extrusion is explained by an open system degassing model with a simultaneous crystallization of the melt some significant br enrichments relative to cl in dome fragments are attributed to interactions with an hydrothermal fluid close to seawater in composition the models allow calculation of cl and br contents of aqueous fluids generated by the different degassing paths cl contents are 0 5 mol l for closed system evolution and vary between 0 2 and 1 mol l during open system evolutions these fluids are able to extract significant amounts of chloride complexed metals and silica from the magma during dome forming eruptions they also may generate mineralization of the wall rocks or the rising dome itself e g silica precipitation which may seal the volcanic system and be responsible for the dome explosivity and the transition from dome forming to plinian eruptive style the cl br ratio of initial melts of p1 eruption 250 is much lower than the basaltic and exospheric ratios 400 suggesting that strong cl br fractionation may occur during the production or the differentiation of subduction related magmas

pre and syn eruptive geochemistry of volcanic gases from soufriere hills of montserrat west indies soufriere hills fumaroles contained magma derived volatiles before and during the eruption initiated in 1995 but also preserved a typical and quite steady hydrothermal composition chemical changes due to increased boiling and a greater input of oxidizing magmatic gas occurred only at galway s soufriere the most active fumarolic field hydrothermal buffering of the fumaroles has been favoured by their remote location 1 2 km from the eruptive vents and by a preferential degassing of the uprising magma through intrusive conduits under the crater high temperature 720 c gas collected from the extruding lava dome in feb 1996 was chemically and isotopically representative of the magmatic gas stream its composition allows assessment of average eruptive fluxes of h2o co2 and hcl which require the degassing of only 2 5 3 times more magma than erupted

modelling reactive halogen formation and ozone depletion in volcanic plumes in this paper we present a purpose built model plumechem to simulate the reactive halogen chemistry in plumes from persistently degassing volcanoes the model includes photolytic gas phase and aqueous phase chemical reactions and dispersion of the plume into the background atmosphere we investigate how high temperature chemistry close to the vent believed to enhance plume nox hox brox and clox affects bro formation in the downwind plume plumechem simulations initialised using output from thermodynamic calculations at 1000 c with atmospheric magmatic gas ratio 0 1 above the compositional discontinuity are in good quantitative agreement with observations of bro so2 and also provide a mechanism whereby clo and oclo may be formed in the plume the model reproduces the observed magnitudes and rates of increase of bro so2 at several volcanoes the hbr content of the initial plume is shown to be an important control in determining the bro so2 ratio and ozone depletion in the downwind plume the model simulates conversion of nox to hno3 and destruction of ozone in the plume providing an explanation for observed elevated hno3 in volcanic plumes and in agreement with an in plume observation of depleted ozone the predicted ozone depletion was locally and regionally significant for three different volcanic plume compositions therefore we present a new model of volcanic plume chemistry supported by observations of volcanic bro and hno3 which identifies hbr emission as a key determinant in ozone depletion by volcanoes

field strength variations of lf radio waves prior to earthquakes in central italy abstract the electric field strength of the lf radio broadcasting rmc principality of monaco which operates at 216 khz has been recorded since january 1991 by two receivers in central italy during the monitoring period we observed two evident attenuations of the field strength in one receiver with durations of 6 10 days the geomagnetic and ionospheric observations carried out in the same time interval do not seem able to explain the attenuation of the radio signal an analysis of the seismic activity occurring in the area between transmitter and receiver has revealed that some days after the attenuations the energy released by earthquakes reaches a maximum the observed attenuation might therefore be precursors of earthquakes we also checked meteorological conditions and found that advections of warm air occurred during both the two anomalous periods it seems possible that these conditions can help the action of preseismic effects in generating irregularities in the vertical gradient of the tropospheric radio refractivity able to produce defocusing of lf radiobroadcast propagation

representation of convective plumes by vertical adjustment open ocean deep water formation involves the interplay of two dynamical processes plumes 1 km wide driven by upright convection and geostrophic eddies 5 km wide driven by baroclinic instability numerical twin experiments are used to address two questions about the plumes can they be represented by a simple mixing process in large scale models if so is it important that the mixing occurs over a finite time tmix or would instantaneous mixing produce the same effect on large scale properties in numerical simulations which resolve the geostrophic eddies we represent the plumes with a slow convective adjustment algorithm which is broadly equivalent to an enhanced vertical diffusivity of density in statically unstable regions the diffusivity depends on tmix the mixing timescale the fidelity of the plume parameterization is then evaluated by comparison with plume resolving simulations of open ocean deep convection integral properties of the plumes such as the temperature census of the convected water and the strength of the rim current that encircles the convecting region are all accurately reproduced by the slow adjustment scheme the importance of choosing an appropriate finite value for tmix is explored by setting tmix 12 hours in some experiments in accordance with scaling considerations and tmix 0 in others corresponding to instantaneous adjustment the conventional assumption in the case of convection into a moderately or strongly stratified ocean the behavior does not significantly depend on tmix however in neutral conditions the slow adjustment does improve the parametric representation our experiments confirm the picture of plumes homogenizing the water column over a time tmix

reactive halogens bro and oclo detected in the plume of soufriere hills volcano during an eruption hiatus volcanic plumes are sites of dynamic chemistry involving halogen gases here we present new data on the relative abundances of so2 bro and oclo gases emitted from soufriere hills volcano shv they were collected during an eruptive hiatus but during sustained degassing at this halogen rich volcano by comparison with data from a previous study during an eruptive phase and application of the data and modeling of villemant et al 2008 we suggest that after consideration of errors either the rate of hbr conversion to bro is variable ranging from 30 to 15 and or the relative partitioning of cl and br into the gas phase from the melt changes according to eruptive activity we examine the potential implications of this for fluid melt partitioning and compare our results with data from the experimental literature our work contributes toward understanding the controls on the bro so2 ratio for volcano monitoring purposes the changes in plume chemistry with regard to bromine at the onset of lava extrusion may be large and rapid oclo was detected in the plume at shv for the first time this species has only previously been detected in emissions from mount etna using ground based methods and from puyehue cordon caulle using satellite based methods no hcho or noy species were detected in the spectra

the 12 900 years bp laacher see eruption estimation of volatile yields and simulation of their fate in the plume we estimated the volatile emissions of the 12 900 years bp eruption of laacher see volcano germany using a modified petrological method glass inclusions in phenocrysts and matrix glasses sampled over the laacher see tephra profile were analysed by synchrotron x ray fluorescence microprobe and electron microprobe to obtain the emitted masses of halogens sulphur and water these data were used to initialize the numerical plume model atham in order to investigate the fate of volcanic gases in the plume and to estimate volatile masses injected into the stratosphere the scavenging efficiency of each volatile component depends on its interactions with both liquid water and ice we found a scavenging efficiency of c 5 for the sulphur species and of only c 30 for hydrogen halides despite their high water solubility our simulations showed that the greatest fraction of hydrometeors freeze to ice due to the fast plume rise and great height of the eruption column for the dry atmospheric conditions of the laacher see eruption the amount of liquid water was not sufficient to completely scavenge hcl and hbr so that a large proportion could reach the stratosphere

oceanic isopycnal mixing by coordinate rotation abstract current numerical models of oceanic circulation differentiate between the eddy diffusion and viscosity transport along the geopotential horizontal and vertical directions only in order to model the effect of anisotropic turbulence as diffusive transport along and across density surfaces the isopycnal mixing tensor has been transformed from a diagonal second rank tensor in the isopycnal coordinate system to a tensor containing off diagonal elements in the geopotential coordinate system

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

volcanic craters pit craters and high level magma feeding systems of a mafic island arc volcano ambrym vanuatu south pacific

etna 2004 2005 an archetype for geodynamically controlled effusive eruptions 1 the 2004 05 eruption of etna was characterised by outpouring of degassed lava from two vents within valle del bove after three months of eruption lava volumes were estimated to be between 18 5 and 32 106 m3 with eruption rate between 2 3 and 4 1 m3 s petrological analyses show that magma is resident in the shallow plumbing system emplaced during the last south east crater activity so2 flux data show no increase at the onset of the eruption and so2 hcl ratios in gas emitted from the eruptive fissure are consistent with a degassed magma no seismic activity was recorded prior to eruption unlike eruptions observed since the 1980 s the purely effusive nature of this eruption fed by a degassed resident magma and the fracture dynamics suggest that magmatic overpressure played a limited role in this eruption rather lateral spreading of etna s eastern flank combined with general inflation of the edifice triggered a geodynamically controlled eruption

geochemistry vs seismo tectonics along the volcanic new hebrides central chain southwest pacific abstract compositional variations major and trace element of pleistocene to present rocks along the volcanic new hebrides central chain southwest pacific are presented and discussed using a new set of analyses we focus in particular on the anomalous mg k lile and lree rich and al and si poor character of the basalts from aoba and santa maria volcanoes and to a lesser extent from ambrym volcano all located in the area where the d entrecasteaux zone collides with the arc in addition we note a compositional transition from normal arc basalts to boninite related high mg andesites at the southern termination of the nhcc the peculiar composition of the rocks of the volcanoes facing the d entrecasteaux zone has traditionally been related more or less directly to the collision subduction occurring in this area we present an alternative hypothesis of a strong geochemical anomaly under santa maria and aoba volcanoes unrelated to this collision in this model a westward and upward invasion of dupal type enriched mantle corroborated by the pattern of intermediate seismicity occurs under this part of the arc in strong contrast to the usual pacific type morb mantle source present under all other volcanoes of the nhcc such a dupal type source may explain the anomalous geochemistry of the resulting volcanic products

experimental constraints on the origin of chlorine emissions at the soufriere hills volcano montserrat experimental study of cl solubility in a rhyolitic melt composition corresponding to the phenocryst free matrix of the recently erupted soufriere hills andesite provides insights into the origin of cl emitted to the atmosphere during the eruption the experiments were done at 25 250 mpa 860 890 c and they involved equilibration of the estimated matrix composition 71 wt sio2 molar na2o k2o al2o3 0 6 with a cl rich aqueous fluid or aqueous fluid hydrosaline brine the cl concentrations in glasses from the experimental run products 0 48 0 68 wt cl are significantly higher than those observed in natural matrix glasses 0 20 wt cl and melt inclusions 0 30 0 07 wt cl these results indicate that if the pre eruptive montserrat magma was vapour saturated the vapour phase would have been cl poor and there was not a co existing hydrosaline brine this interpretation based on cl solubility data is supported by the observed coincidence between remote sensing measurements of cl emissions as hcl and petrological estimates of cl emissions based on the volume of magma extruded and cl contents of melt inclusions and matrix glasses with correction for groundmass crystallization during ascent the cl emissions during the soufriere hills eruption are thus proposed to simply reflect syn eruptive degassing of magma during ascent

depletion rates of sulfur dioxide in tropospheric volcanic plumes the tropospheric sulfur cycle has been closely studied from the standpoint of anthropogenic emissions but less so with respect to volcanic sources we document here evidence for wide variation in lifetimes of volcanic so2 in the troposphere at one extreme our observations of the plume associated with the lavadome eruption of soufriere hills volcano montserrat suggest loss of gaseous so2 at rates exceeding 10 3 s 1 while this efficent so2 depletion reflects unusual environmental factors published measurements for mount etna s plume approach these rapid rates in such cases source strengths of so2 must significantly exceed apparent fluxes measured several kilometres downwind this implies that meteorological and geographic factors as well as volcanic degassing rates should be considered in the interpretation of fluxes of so2 measured beyond source vents with ramifications for volcano monitoring and eruption prediction furthermore since most calculations of global volcanic fluxes of sulfur and other species to the troposphere are based on extrapolation of so2 flux data they may underestimate true source strengths finally we consider that fast sulfur chemistry may also prevail in convecting eruption columns resulting in partial tropospheric scrubbing of sulfur from stratosphere bound plumes

variations of cl f and s in mount etna s plume italy between 1992 and 1995 this study investigates data on the cl f and s concentrations of plume filter samples collected between 1992 and 1995 from mount etna the samples were collected during eruptive and noneruptive activity and show fairly constant cl f ratios but wide variation in the cl s ratios the determination of the cl f ratio between 5 and 14 allows an estimate of f degassing to be derived that ranges from 10 to 30 of the initial f content of the magma the variation in the cl s ratio fits an empirical two stage degassing model where gas with high cl s ratio is discharged during quiescient degassing and gas with low cl s ratios is discharged during eruptive degassing the typical permanent degassing occurs from a depth at which chlorine exsolution exceeds sulfur exsolution cl s 1 the opposite of this behavior is observed during eruptive periods when significant sulfur degassing occurs because magma degasses at near atmospheric pressure cl s 0 1 the cl s ratio in the plume characterizing the type of degassing has the potential to be a useful geochemical tool for monitoring the volcano

radio emission associated with rock fracture possible application to the great chilean earthquake of may 22 1960 stress induced piezoelectric fields produce freely propagating electromagnetic radiation when microscopic rock fractures occur in quartz bearing rocks a laboratory study is presented which shows that electromagnetic emissions are produced when microfractures occur in westerly granite a detailed model is presented for the emission process which allows an estimate of the total radiated power from an individual microfracture on the basis of these results a case is presented that an unusual radio emission seen on several widely separated radio astronomy receivers in the northern hemisphere on may 16 1960 was due to a stress induced microfracture along the chilean fault this radio event occurred 6 days prior to the great chilean earthquake of may 22 1960 and may have been a precursor to one of the largest earthquakes of this century

seismic electromagnetic signals sems explained by a simulation experiment using electromagnetic waves abstract the propagation characteristics of seismic electromagnetic signals sems both at an ultra low frequency ulf and at a very low frequency vlf are discussed based on a model experiment of propagation of electromagnetic em waves in the earth s crust and atmospheric waveguide a granite slab and two aluminium plates simulated the earth s crust ionosphere and underground conductive layer respectively the greek archipelago was modeled using a geographical map with the ocean covered by aluminium foil the intensity of em waves transmitted from a model hypocenter was mapped to investigate the influence of the ocean the propagation of vlf waves over the long distance was obtained while that of ulf indicated the exponential decay from the epicenter this experiment considered waveguides might explain the ocean s effect on the selectivity and the long distance propagation of sems presumably including seismic electric signals ses in the van method

degassing dynamics of basaltic lava lake at a top ranking volatile emitter ambrym volcano vanuatu arc persistent lava lakes are rare on earth and provide volcanologists with a remarkable opportunity to directly investigate magma dynamics and degassing at the open air ambrym volcano in vanuatu is one of the very few basaltic arc volcanoes displaying such an activity and voluminous gas emission but whose study has long remained hampered by challenging accessibility here we report the first high temporal resolution every 5 s measurements of vigorous lava lake degassing inside its 300 m deep benbow crater using op ftir spectroscopy our results reveal a highly dynamic degassing pattern involving i recurrent 100 200 s short period oscillations of the volcanic gas composition and temperature correlating with pulsated gas emission and sourced in the upper part of the lava lake ii a continuous long period 8 min modulation probably due to the influx of fresh magma at the bottom of the lake and iii discrete co2 spike events occurring in coincidence with the sequential bursting of meter sized bubbles which indicates the separate ascent of large gas bubbles or slugs in a feeder conduit with estimated diameter of 6 1 m this complex degassing pattern measured with unprecedented detail and involving both coupled and decoupled magma gas ascent over short time scales markedly differs from that of quieter lava lakes at erebus and kilauea it can be accounted for by a modest size of benbow lava lake and its very high basalt supply rate 20 m3 s 1 favouring its rapid overturn and renewal we verify a typical basaltic arc signature for ambrym volcanic gas and based on contemporaneous so2 flux measurements we evaluate huge emission rates of 160 gg d 1 of h2o 10 gg d 1 of co2 and 8 gg d 1 of total acid gas so2 hcl and hf during medium activity of the volcano in 2008 such rates make ambrym one of the three most powerful volcanic gas emitters at global scale whose atmospheric impact at local and regional scale may be considerable

a global synthesis of lava lake dynamics abstract active lava lakes represent a variety of open vent volcanism in which a sizable body of lava accumulates at the top of the magma column constrained by the vent and or crater geometry the longevity of lava lakes reflects a balancing of cooling and outgassing occurring at the surface and input of hot and gas rich magma from below due to their longevity and relative accessibility lava lakes provide a natural laboratory for studying fundamental volcanic processes such as degassing convection and cooling this article examines all seven lakes that existed at the time of writing in 2018 located in the pacific antarctica africa and south and central america these lakes span all tectonic environments and a range of magma compositions we focus on analysis of the lake surface motion using image velocimetry which reveals both similarities and contrasts in outgassing and lake dynamics when comparing the different lakes we identify two categories of lake behavior organized erta ale nyiragongo k lauea after 2011 and erebus and chaotic villarrica masaya marum this division does not map directly to lake size viscosity gas emission rate or temperature instead when examined together we find that the lakes follow a linear relationship between average surface speed and the ratio of total gas flux to lake surface area this relationship points to the combined importance of both flux and lake size in addition to the total volume of gas emission and suggests that a shared deep mechanism controls the supply of heat and gas to all lakes on the other hand the differences between chaotic and organized lakes highlight the important role of the geometry of the conduit lake transition which superimposes a shallow signal on that of the deep circulation the spatial patterns of surface motion we document suggest that the release of gas bubbles at chaotic lakes is more efficient i e bubbles are less likely to be retained and recycled compared with organized lakes in addition the data presented here indicate that the solidified crust of organized lakes plays a role in regulating convection and outgassing in lava lakes

the southern ocean at the last glacial maximum a strong sink for atmospheric carbon dioxide analysis of satellite ocean color sea surface temperature and sea ice cover data reveals consistent patterns between biological production iron availability and physical forcings in the southern ocean the consistency of these patterns in conjunction with information on physical conditions during the last glacial maximum lgm enables estimates of export production at the lgm the lgm southern ocean experienced increased wind speeds colder sea surface and atmospheric temperatures increased deposition of atmospheric dust and a greatly expanded winter sea ice cover these variations had strong effects on southern ocean ecology and on air sea fluxes of co2 the seasonal ice zone siz was much larger at the lgm 30 million km2 than at present 19 million km2 the antarctic polar front pf likely marked the northern boundary of this expanded siz throughout the southern ocean as it does today in the drake passage region a large northward shift in the position of the pf during glacial times is unlikely due to topographic constraints north of the pf the increased flux of aeolian dust during glacial times altered phytoplankton species composition and increased export production and as a result this region was a stronger sink for atmospheric co2 than in the modern ocean south of the pf interactions between the biota and sea ice strongly influence air sea gas exchange over seasonal timescales the combined influence of melting sea ice and increased aeolian dust flux with its associated iron increased both primary and export production by phytoplankton over daily monthly timescales during austral spring summer resulting in a strong flux of co2 into the ocean heavy ice cover would have minimized air sea gas exchange over much of the rest of the year thus an increased net flux of co2 into the ocean is likely during glacial times even in areas where annual primary production declined we estimate that export production in the southern ocean as a whole was increased by 2 9 3 6 gt c yr 1 at the lgm relative to the modern era altered seasonal sea ice dynamics would further increase the net flux of co2 into the ocean thus the southern ocean was a strong sink for atmospheric co2 and contributed substantially to the lowering of atmospheric co2 levels during the last ice age

laboratory measurements anomalous 0 1 0 5 hz streaming potential under geochemical changes implications for electrotelluric precursors to earthquakes streaming potentials resulting from flow of various salt solutions in rock were measured on saturated sediments fontainebleau sandstones the streaming potential v was found to be proportional to the driving pore pressure p pulses of amplitude 15 40 mv in the frequency range of 0 1 to 0 5 hz were observed when the conductivity of the injected water was decreased and the fluid flow rate was relatively low corresponding to a darcian velocity of 17 to 30 cm h the amplitudes of these pulses are 47 to 133 of the corresponding steady components of the v values such geochemically induced effects may possibly be responsible for the frequency signals from 0 1 to 0 5 hz that were sometimes observed before an earthquake

linking glacial interglacial states to multiple equilibria of climate glacial interglacial cycles are often described as an amplified global response of the climate to perturbations in solar radiation caused by oscillations of earth s orbit however it remains unclear whether internal feedbacks are large enough to account for the radically different glacial and interglacial states here we provide support for an alternative view glacial interglacial states are multiple equilibria of the climate system which exist for the same external forcing we show that such multiple equilibria resembling glacial and interglacial states can be found in a complex coupled general circulation model of the ocean atmosphere sea ice system the multiple states are sustained by ice albedo feedback modified by ocean heat transport and are not caused by the bi stability of the ocean s overturning circulation in addition expansion contraction of the southern hemisphere ice pack over regions of upwelling regulating outgassing of co 2 to the atmosphere is the primary mechanism behind a large pco 2 change between states

monitoring so2 emission at the soufriere hills volcano implications for changes in eruptive conditions correlation spectrometer measurements of sulfur dioxide so2 emission rates during the current eruption of the soufriere hills volcano montserrat have contributed towards identifying different phases of volcanic activity so2 emission rate has increased from 550 td 1 6 4 kgs 1 after july 1996 with the uncertainty associated with any individual measurement ca 30 significantly enhanced so2 emission rates have been identified in association with early phreatic eruptions 800 td 1 9 3 kgs 1 and episodes of vigorous dome collapse and pyroclastic flow generation 900 to 1500 td 1 10 4 to 17 4 kgs 1 so2 emission rate has proved a useful proxy measurement for magma production rate observed so2 emission rates are significantly higher than those inferred from analyses of glass inclusions in phenocrysts implying the existence of a s rich magmatic vapour phase

the relationship between degassing and ground deformation at soufriere hills volcano montserrat we examine the correlations between so2 emission rate seismicity and ground deformation in the month prior to the 25 june 1997 dome collapse of the soufriere hills volcano montserrat during this period the volcano exhibited a pattern of cyclic inflation and deflation with an 8 14 h period we find that so 2 emission rates measured by cospec correlate with the amplitude of these tilt cycles and that higher rates of so 2 emission were associated with stronger ground deformation and enhanced hybrid seismicity within tilt cycles degassing peaks coincide with maximum deformation gradients increases in the amount of gas in the magma conduit feeding the dome probably due to increases in volatile content of ascending magma volume can account for the observed increases in tilt amplitude hybrid seismicity and so2 emission rate q 2000 elsevier science b v all rights reserved

distribution of sulfur aerosol precursors in the spcz released by continuous volcanic degassing at ambrym vanuatu abstract the melanesian volcanic arc mva emits about 12 kt d 1 of sulfur dioxide so2 to the atmosphere from continuous passive non explosive volcanic degassing which contributes 20 of the global so2 emission from volcanoes here we assess from up to date and long term observations the so2 emission of the ambrym volcano one of the dominant volcanoes in the mva and we investigate its role as sulfate precursor on the regional distribution of aerosols using both satellite observations and model results at 1 1 spatial resolution from wrf chem gocart without considering aerosol forcing on clouds our model parameterizations for convection vertical mixing and cloud properties provide a reliable chemical weather representation making possible a cross examination of model solution and observations this preliminary work enables the identification of biases and limitations affecting both the model missing sources and satellite sensors and algorithms for aerosol detection and classification and leads to the implementation of improved transport and aerosol processes in the modeling system on the one hand the model confirms a 50 underestimation of so2 emissions due to satellite swath sampling of the ozone monitoring instrument omi consistent with field studies the omi irregular sampling also produces a level of noise that impairs its monitoring capacity during short term volcanic events on the other hand the model reveals a large sensitivity on aerosol composition and aerosol optical depth aod due to choices of both the source function in wrf chem and size parameters for sea salt in flexaod the post processor used to compute offline the simulated aod we then proceed to diagnosing the role of so2 volcanic emission in the regional aerosol composition the model shows that both dynamics and cloud properties associated with the south pacific convergence zone spcz have a large influence on the oxidation of so2 and on the transport pathways of volcanic species across the south pacific atmosphere for example in the tropical cloudy air the sulfate production in the aqueous phase is very efficient resulting in the formation of a large cloud of highly scattering sulfate aerosols advected horizontally to eastern indonesia in agreement with the aod feature captured by modis aqua but missed in caliop calipso lidar products model sensitivity experiments indicate that aerosol re suspension due to evaporating droplets is a significant pathway for the supply of volcanic sulfur species in the remote marine boundary layer by strongly modulating the irreversible loss due to wet scavenging this aerosol process has a similar influence on the sulfur burden as natural emission from volcanoes or biogenic sources like dimethyl sulfate dms the results emphasize the importance of mva passive degassing and spcz dynamics on the aerosol background and raise questions about potential impacts on the local climate and marine ecosystems

electromagnetic precursors to earthquakes in the ulf band a review of observations and mechanisms despite over 2 decades of international and national monitoring of electrical signals with the hope of detecting precursors to earthquakes the scientific community is no closer to understanding why precursors are observed only in some cases laboratory measurements have demonstrated conclusively that self potentials develop owing to fluid flow and that both resistivity and magnetization change when rocks are stressed however field experiments have had much less success many purported observations of low frequency electrical precursors are much larger than expectations based on laboratory results in some cases no precursors occurred prior to earthquakes or precursory signals were reported with no corresponding coseismic signals nonetheless the field experiments are in approximate agreement with laboratory measurements maximum resistivity changes of a few percent have been observed prior to some earthquakes in china but the mechanism causing those changes is still unknown anomalous electric and magnetic fields associated with fluid flow prior to earthquakes may have been observed finally piezomagnetic signals associated with stress release in earthquakes have been documented in measurements of magnetic fields

gas and particle emissions from soufriere hills volcano montserrat west indies characterization and health hazard assessment the soufriere hills volcano montserrat erupting since 18 july 1995 intensified its degassing in early 1996 with the continuing growth of the lava dome inside the summit crater during this period of increased activity between 11 and 18 march 1996 we measured gases and particles within the visible plume to determine whether at that time it posed a health risk to the population of plymouth the capital town which is 5 km southwest downwind and was then still occupied gravimetric measurements were made of total suspended particles tsp and particles having an aerodynamic diameter of less than 10 m pm10 measurements were made of sulphur dioxide so2 hydrochloric acid hcl hydrofluoric acid hf nitric acid hno3 acetic acid ch3cooh formic acid hcooh and particulate sulphate so4 2 chloride cl nitrate no3 fluoride f methanesulphonate ch3so3 acetate ch3coo formate hcoo ammonium nh4 sodium na and acidity h trace metals having human health implications chromium cr nickel ni cobalt co copper cu zinc zn arsenic as selenium se cadmium cd tin sn mercury hg and lead pb were also determined mean concentrations of hcl so2 and hf obtained in the town of plymouth were 14 0 5 9 and 0 8 ppbv respectively corresponding concentrations in the mixed plume on the crater edge were 533 168 and 22 ppbv there were no direct emissions of hno3 although nitrate was detected in coarse particles at the source higher concentrations of ch3cooh and hcooh were measured close to the crater mean tsp and pm10 were 64 and 15 g m 3 in plymouth and 455 and 47 g m 3 on the upper volcano slope aerosols were highly acidic at the source but rapidly neutralised during transport trace metals were enriched in the aerosol relative to crater surface material the concentrations of the acid gases sulphur dioxide in particular and particles were found to be too small to pose a health hazard at the time of these measurements when relatively modest volcanic activity was occurring

extraterrestrial lava lakes abstract active lava lakes are rare on earth with only ten documented examples all formed by lavas of basaltic composition and housed inside summit craters or calderas the existence of lava lakes on other planetary bodies may imply similarities in either composition or volcano tectonic settings and so has important implications for understanding the link between melt production and volcanism we review lava lakes on earth and other planets particularly active caldera like features interpreted to be currently containing active lava lakes on jupiter s moon io and features interpreted as remnants of lava lakes on venus and mars mercury and the moon do not boast the major calderas or shield volcanoes of their larger rocky neighbors partly due to a horizontally compressive tectonic regime arising from global contraction that makes it difficult to move melts through the upper crust we discuss the evidence for active lava lakes on io and show how modeling based on terrestrial lava lakes can reveal how these phenomena differ on both bodies the superficial similarities do not necessarily imply that the plumbing is similar observations of the largest lava lake on io loki patera provide insight into the nature of ionian lava lakes in general which may be more similar to eruptive episodes on the east pacific rise on earth which lead to temporary lava lakes although temporal data for io s lava lake activity are scarce studies of temporal variability of lava lakes on earth are useful for providing ground truth for comparisons future studies of earth by remote sensing and field observations and of io by both ground based observations and future missions are needed to answer many questions including why lava lakes rare on earth appear to be common on io

low frequency magnetic field measurements near the epicenter of the ms 7 1 loma prieta earthquake the authors report the results of measurements of low frequency magnetic noise by two independent monitoring systems prior to the occurrence of the m sub s 7 1 loma prieta earthquake of 17 october 1989 their measurements cover 25 narrow frequency bands in the more than six decade frequency range 0 01 hz 32 khz with a time resolution varying from a half hour in the ulf range 0 01 10 hz to one second in the elf vlf range 10 hz 32 khz the ulf system is located near corralitos about 7 km from the epicenter the elf vlf system is located on the stanford campus about 52 km from the epicenter analysis of the elf vlf system is located on the stanford campus about 52 km from the epicenter analysis of the elf vlf data has revealed no precursor activity that they can identify at this time however the ulf data have some distinctive and anomalous features first a narrow band signal appeared in the range 0 05 0 2 hz around september 12 and persisted until the appearance of the second anomalous feature which consisted of a substantial increase in the noise background starting on 5 october and covering almost the entire frequency range of the ulf system third there was an anomalousmore dip in the noise background in the range 0 2 5 hz starting one day ahead of the earthquake finally and perhaps most compelling there was an increase to an exceptionally high level of activity in the range 0 01 0 5 hz starting approximately three hours before the earthquake there do not appear to have been any magnetic field fluctuations originating in the upper atmosphere that can account for this increase further while the systems are sensitive to motion seismic measurements indicate that there were no significant shocks preceding the quake thus the various anomalous features in the data and in particular the large amplitude increase in activity starting three hours before the quake may have been magnetic precursors less

a study of anomalous underground electric field variations associated with a volcanic eruption continuous measurements of vertical subsurface geoelectric fields in the frequency range dc 0 6 hz and 1 3 khz vlf are reported anomalous field variations of the ulf band are observed a few days prior to and a month after a minor volcanic eruption of mt mihara the variations displayed essentially distorted pulses rising sharply initially gradually decreasing and then suddenly falling off the electric field variations also seem to extend to the vlf band it is felt that the anomalous electric field variations were caused by electrokinetic phenomena induced by variations of hydrothermal circulation around the crater or by variations of crack density due to volcanic activity

rapid chemical evolution of tropospheric volcanic emissions from redoubt volcano alaska based on observations of ozone and halogen containing gases abstract we report results from an observational and modeling study of reactive chemistry in the tropospheric plume emitted by redoubt volcano alaska our measurements include the first observations of br and i degassing from an alaskan volcano the first study of o 3 evolution in a volcanic plume as well as the first detection of bro in the plume of a passively degassing alaskan volcano this study also represents the first detailed spatially resolved comparison of measured and modeled o 3 depletion in a volcanic plume the composition of the plume was measured on june 20 2010 using base treated filter packs for f cl br i and s at the crater rim and by an instrumented fixed wing aircraft on june 21 and august 19 2010 the aircraft was used to track the chemical evolution of the plume up to 30 km downwind 2 h plume travel time from the volcano and was equipped to make in situ observations of o 3 water vapor co 2 so 2 and h 2 s during both flights plus remote spectroscopic observations of so 2 and bro on the august 19th flight the airborne data from june 21 reveal rapid chemical o 3 destruction in the plume as well as the strong influence chemical heterogeneity in background air had on plume composition spectroscopic retrievals from airborne traverses made under the plume on august 19 show that bro was present 6 km downwind 20 min plume travel time and in situ measurements revealed several ppbv of o 3 loss near the center of the plume at a similar location downwind simulations with the plumechem model reproduce the timing and magnitude of the observed o 3 deficits and suggest that autocatalytic release of reactive bromine and in plume formation of bro were primarily responsible for the observed o 3 destruction in the plume the measurements are therefore in general agreement with recent model studies of reactive halogen formation in volcanic plumes but also show that field studies must pay close attention to variations in the composition of ambient air entrained into volcanic plumes in order to unambiguously attribute observed o 3 anomalies to specific chemical or dynamic processes our results suggest that volcanic eruptions in alaska are sources of reactive halogen species to the subarctic troposphere

internal structure of mount merapi indonesia derived from long offset transient electromagnetic data 1 a long offset transient electromagnetic lotem survey was carried out on merapi volcano indonesia in 1998 lotem data have been recorded at 41 receiver locations which cover a 10 km w e and a 15 km s n profile the signals were transmitted at four locations on the south west and north sides of merapi the data were interpreted with one dimensional 1 d inversions in addition two particular features were investigated with 3 d modeling on the south flank the magnetic field data show strong 3 d distortions consistently over the profile which can only be explained by a conductive near surface structure like a fracture filled with conductive fluids the simulation of topographic effects shows that the interpretation is not significantly affected on both profiles the most striking feature is a conductive layer of 20 m at depths of 500 1000 m below the surface and a thickness of 1 2 km the cause of the increased conductivity may be different for the summit area the intermediate zone and at the flanks below the summit in vicinity of the conduit the decrease in resistivity is produced either by hydrothermal fluids by partial melts or rocks altered by the hydrothermal system or by a combination in the intermediate zone between the conduit and the flanks either alteration or hydrothermal fluids may be the source of the conductivity increase fluids seem to be the most likely cause for the conductive layer at the flanks and the west east striking anomaly from the resistivity of the conductive layer and the typical porosity of volcanic rock we estimate fluid resistivities of 0 2 1 m

interpretation of very long period tremors at ambrym volcano vanuatu as quasi static displacement field related to two distinct magmatic sources 1 a 3 component broadband seismometer sts 2 has been deployed on the sw slope of ambrym vanuatu a large caldera volcano with two persistent lava lakes from july to november 2000 well polarized very long period tremors 18 22s vlpts occurred quite continuously whereas other seismic signal with periods of 9s 6 7s 5s 2 3 2 7s 1 95s and 1s were intermittent vlpts signals show two clearly distinct directions pointing towards the caldera polarization orientations suggest two sources the first one and the most active fits with the zone from which silicic lava flows erupted in 1986 in the central to eastern part of the caldera the second one corresponds to the active zone formed by the complex marum volcanic center and the benbow cone in the western part of the depression structure the depths are estimated between 2 7 2 9 km with respect to sea level vlpts are interpreted as the quasi static displacement field of two nondestructive sources they indicate the persistent continuing magmatic activity beneath the eastern floor of the caldera although no volcanic activity is observed in this area and the more obvious but less active corresponding to the lava lakes these data also corroborate the complex internal structure of the ambrym caldera suggested by geological data and bimodal magmatism basaltic 50 sio2 and silicic 60 sio2

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

overview of the eruption of soufriere hills volcano montserrat 18 july 1995 to december 1997 the onset of phreatic volcanic activity at the soufriere hills volcano montserrat on 18 july 1995 followed a three year period of heightened volcano seismic activity beneath the island phreatic explosions gave way to continuous eruption of juvenile andesitic magma in the form of a lava dome on or around 15 november 1995 magma production rate has varied leading to changes in eruptive style an explosive eruption on 17 september 1996 followed a period of enhanced dome growth and large scale gravitational collapses from its eastern flank increasing dome volume led to stressing and overtopping of the confining crater walls to the southwest north and west during early 1997 sustained high magma production rate since june 1997 has led to three periods of major gravitational dome collapses followed by vulcanian explosive eruptions dome growth re started immediately after the cessation of the latest of these explosive phases in october 1997 and continues as of december 1997

measurements of electric potential variation by piezoelectricity of granite from laboratory experiments we observed that unloading stress on a piece of granite induced a pulsed electric potential variation which decays exponentially with a time constant ranging from 1 5 to 4 0 s the electric potential variation depends on the magnitude and the sustaining time of applied stress indicating that the variation is due to piezoelectricity and migration of bound charges that compensate the piezoelectric polarization an apparent piezoelectric coefficient of granite was obtained to be about 1 4 10 15 c n three orders of the magnitude smaller than that of a single crystal of quartz

magma and volatile supply to post collapse volcanism and block resurgence in siwi caldera tanna island vanuatu arc v24c 04 allen s r 2005 complex spatterand pumice rich pyroclastic deposits from an andesitic caldera forming eruption the siwi pyroclastic sequence tanna vanuatu bulletin of volcanology 67

emission of electromagnetic radiation preceding the ito seismic swarm of 1989 there have been several reports1 8 of electromagnetic radiation being detected in air and or underground before large earthquakes or volcanic eruptions unfortunately such measurements are often plagued by contamination from other sources of noise we have developed an electrode system that is effective at filtering out urban and atmospheric background noise here we report the detection of anomalous electromagnetic signals several hours before the occurrence of large earthquakes near ito city japan about 150 km from the location of the electrodes we have also detected anomalous signals about one day before an undersea volcanic eruption that constituted part of the same seismic swarm near ito although the mechanism responsible for such signals is still unclear these results indicate that their monitoring could be valuable for the prediction of seismic activity

isopycnal mixing in ocean circulation models abstract a subgrid scale form for mesoscale eddy mixing on isopycnal surfaces is proposed for use in non eddy resolving ocean circulation models the mixing is applied in isopycnal coordinates to isopycnal layer thickness or inverse density gradient as well as to passive scalars temperature and salinity the transformation of these mixing forms to physical coordinates is also presented

the role of deep ocean circulation in setting glacial climates the glacial cycles of the pleistocene involve changes in the circulation of the deep ocean in important ways this review seeks to establish what were the robust patterns of deep sea water mass changes and how they might have influenced important parts of the last glacial cycle after a brief review of how tracers in the modern ocean can be used to understand the distribution of water masses i examine the data for biogeochemical circulation rate and conservative tracers during glacial climates some of the robust results from the literature of the last 30 years include a shoaled version of northern source deep water in the atlantic expanded southern source water in the abyss and deep ocean salt rather than heat stratification of the last glacial maximum lgm deep sea and several lines of evidence for slower overturning circulation in the southern deep cell we combine these observations into a new idea for how the ocean atmosphere system moves from interglacial to glacial periods across a single cycle by virtue of its influence on the melting of land based ice around antarctica cooling north atlantic deep water nadw leads to a cold and salty version of antarctic bottom water aabw this previously underappreciated feedback can lead to a more stratified deep ocean that operates as a more effective carbon trap than the modern helping to lower atmospheric co 2 and providing a mechanism for the deep ocean to synchronize the hemispheres in a positive feedback that drives the system to further cooling

pyroclastic flows generated by gravitational instability of the 1996 97 lava dome of soufriere hills volcano montserrat numerous pyroclastic flows were produced during 1996 97 by collapse of the growing andesitic lava dome at soufriere hills volcano montserrat measured deposit volumes from these flows range from 0 2 to 9 106 m flows range from discrete single pulse events to sustained large scale dome collapse events flows entered the sea on the eastern and southern coasts depositing large fans of material at the coast small runout distance 1 km flows had average flow front velocities in the order of 3 10 m s while flow fronts of the larger runout distance flows up to 6 5 km advanced in the order of 15 30 m s many flows were locally highly erosive field relations show that development of the fine grained ash cloud surge component was enhanced during the larger sustained events periods of elevated pyroclastic flow productivity and sustained dome collapse events are linked to pulses of high magma extrusion rates

locating source regions of precursory seismo electric fields and the mechanism generating electric field variations abstract electrodes consisting of a steel pipe in a deep borehole and a grounded wire surrounding the borehole were constructed to measure vertical electric fields whereas conventional electrodes measure horizontal fields three years of monitoring showed that the anomalous variations in vertical underground electric fields preceding earthquakes and volcanic eruptions are much clearer than the variations in horizontal fields the data also showed that there is much less man made noise in the vertical fields to determine whether these observed anomalies are forerunners of seismic disturbance a system developed to locate precisely the source regions of underground vertical electric fields or volcanic tremors has been continuously operated the system uses three or more time lags calculated by cross correlating the electric fields or volcanic tremors recorded at four or more monitoring stations if this system reveals the intensity distributions of the sources prediction of imminent earthquakes and volcanic eruptions will become possible to explain the mechanisms by which precursory electric field variations are generated a model is proposed in which the electric field variations are generated by earth current variations caused by increased electric conductivity in source regions before an earthquake the conductivity is increased by free electrons and positive holes created on the fresh fracture surfaces caused by microcracks that occur before rock failure in the earth s crust the model can explain precursory electrical phenomena which are observed not only in the field before an earthquake but also in the laboratory before rock failure

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

surge in sulphur and halogen degassing from ambrym volcano vanuatu volcanoes provide important contributions to atmospheric budgets of so2 and reactive halogens which play significant roles in atmospheric oxidative capacity and radiation however the global source strengths of volcanic emissions remain poorly constrained these uncertainties are highlighted here by the first measurements of gas emission rates from ambrym volcano vanuatu our initial airborne ultraviolet spectroscopic measurements made in january 2005 indicate fluxes of 18 270 kg s 1 of so2 and 62 110 g s 1 of bro into the atmosphere placing ambrym amongst the largest known contemporary point sources of both these species on earth we also estimate high cl and f fluxes of 8 14 and 27 50 kg s 1 respectively for this period further observations using both airborne and spaceborne remote sensing reveal a fluctuating so2 output between 2004 and 2008 with a surge in the first half of 2005 and underline the substantial contribution that a single passively degassing volcano can make to the atmospheric budget of sulfur and halogens

hcl emissions at soufriere hills volcano montserrat west indies during a second phase of dome building november 1999 to october 2000 hcl so2 mass ratios measured by open path fourier transform spectroscopy op ftir in the volcanic plume at soufriere hills volcano montserrat are presented for the second phase of dome building between november 1999 and november 2000 hcl so2 mass ratios of greater than 1 and hcl emission rates of greater than 400 t day 1 characterise periods of dome building for this volcano the data suggest that chlorine partitions into a fluid phase as the magma decompresses and exsolves water during ascent this is substantiated by a correlation between chlorine and water content in the melt derived from the geochemical analysis of plagioclase melt inclusion and matrix glasses from phase i and ii of dome growth the matrix glass from the november 1999 and march 2000 domes indicate an open system degassing regime with a fluid melt partition coefficient for chlorine of the order of 250 300 september 1997 glasses have higher chlorine contents and may indicate a switch to closed system degassing prior to explosive activity in september and october 1997 the op ftir hcl time series suggests that hcl emission rate is strongly related to changes in eruption rate and we infer an emission rate of over 13 5 kt day 1 hcl during a period of high extrusion rate in september 2000 a calculation of the hcl emission rate expected for varying extrusion rates from the open system degassing model suggests a hcl emission rate of the order of 1 4 kt day 1 is indicative of an extrusion rate of between 2 and 8 m3 s 1 monitoring of hcl at soufriere hills volcano provide a proxy for extrusion rate with changes in ratio between hcl and so2 occurring rapidly in the plume order of magnitude changes occur in hcl emission rates over the time scale of hours to days making these changes easy to detect during the day to day monitoring of the volcano mean water emission rates are calculated to range from 9 24 kt day 1 during dome building activity calculated from the predicted mass ratio of h2o hcl in the fluid at the surface and ftir derived hcl emission rates

high frequency seismo electromagnetic effects abstract electromagnetic perturbations caused by natural geophysical activity such as earthquakes and volcanic eruptions have been studied since the great alaskan earthquake in 1964 in recent years interest has been increasing because when a precursor event occurs it normally does so less than a few hours before the shock this paper presents a review of the high frequency seismo electromagnetic phenomena already observed and occurring before as well as after the shock the term high frequency is to be taken in the seismic sense i e larger than a few hertz mechanisms that might produce these seismo electromagnetic emissions will be described it is shown that at the moment a causal relationship between electromagnetic signals and seismic activity still remains to be demonstrated theoretical as well as intensive experimental studies are necessary to understand the physical processes responsible for seismo or volcano electric variations electrical resistivity variations electromagnetic effects associated with dilatance as well as electromagnetic fields generated during laboratory experiments or ionospheric disturbances

physical properties of the variations of the electric field of the earth preceding earthquakes i abstract in an earlier paper we described the physical properties of the preseismic transient variations in the electrotelluric field the present letter clarifies a few points that were not properly emphasized in our previous publications furthermore recent results like that of the destructive kalamata earthquake on september 13 1986 indicate that the duration of a preseismic electric signal may reach considerably high values lasting up to several hours

fluid flow near reservoir lakes inferred from the spatial and temporal analysis of the electric potential electric self potential sp variations have been monitored continuously from 1995 to 1998 at 14 points on a ridge separating the roselend and la gittaz reservoir lakes in the french alps the lakes have level variations of at least 50 m over yearly cycles seasonal variations of sp associated with lake level variations are observed on five points of the array for three points located on the banks of the lakes a positive correlation to the lake level variations is observed with a maximal amplitude of about 180 mv corresponding to an average response of 2 4 mv per meter of water for two points located on the bottom of each lake the correlation is negative with a maximal magnitude of about 50 mv corresponding to an average response of 1 1 mv per meter of water two independent temporary electrical arrays located on the banks of each lake confirm these measurements and allow a better spatial characterization of the sources associated with the observed sp variations in particular near the roselend lake the electrical response to lake level variations is increasing for decreasing altitude the measured sp variations are proposed to result from the electrokinetic coupling associated with a vertical groundwater flow connecting a constant pore pressure source to the bottom of the lakes numerical modeling indicates that the spatial variation of the response and the nonlinear response observed at one point can be explained by leakage currents in the conductive lake water the values of the streaming potential coefficient spc measured in the laboratory with crushed rock samples from the site range from 14 to 50 mv 0 1 mpa for an electrolyte resistivity of 40 m and are compatible to first order with the magnitude of the observed seasonal sp variations a detailed quantitative electrokinetic modeling is currently limited mainly by the poor knowledge on the contribution of electrical leakage currents and the local variability of the spc this experiment indicates that spatial and temporal variations of the electric potential are promising tools to characterize and monitor shallow groundwater flow and provide practical data for the investigation of groundwater flow associated with volcanic or tectonic activity

streaming potential in volcanic rocks from mount pelee streaming potential and electric conductivity have been measured in a laboratory on 11 consolidated samples coming from five deposits of the different evolutionary stages of mount pelde volcano the streaming potential coupling coefficient ranges from 35 to 4905 mv mpa 1 and increases with increasing permeability this increase is mainly due to the dependency of rock effective conductivity with permeability the permeability of the samples varies from 0 146x10 12 to 34x10 12 m 2 the zeta potential at ph 7 and water conductivity of 2 1x10 4 s m l is relatively small for the majority of the samples it ranges from 4 to 19 rev according to water conductivity analysis on mount pel e streaming potential coupling coetficients of 25 to 406 mv mpa 1 can be expected for this volcano

mineral disequilibrium in lavas explained by convective self mixing in open magma chambers characteristic features of many porphyritic andesite and dacite lavas are that they are rich in crystals and display a range of disequilibrium features including reversely zoned crystals resorption surfaces wide ranges of mineral compositions and minerals which are not in equilibrium with the surrounding rock matrix these features are often interpreted as evidence of the mixing of magmas of contrasting composition temperature and origin1 2 here however we propose that such features can also be caused by convection within a magma body with a single composition that is heated from below and cooled from above we describe petrological observations of andesite lava erupted at the soufriere hills volcano montserrat which indicate a heating event and the intermingling of crystals that have very different thermal histories we present experimental data on a representative groundmass composition of this lava which indicate that it is difficult to explain the calcic compositions of plagioclase overgrowth rims and microphenocrysts unless parts of the magma were at temperatures much higher than the inferred average temperature the concept of convective self mixing allows us to explain the occurrence of compositions of minerals that apparently cannot coexist under equilibrium conditions

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