the crystallization of lava lakes thermal convection driven by the kinetic undercooling of solidification can produce compositional and textural variations in an initially uniform lava flow that is cooled predominantly from above we show that such kinetic undercooling is sufficient to drive convection at high rayleigh numbers even in shallow lava lakes we then employ a theoretical model that includes the effects of convection at high rayleigh number to make predictions of the complete evolution of the lava we show that predictions of the rate of growth of solid crust at the surface of the lake do not differ much from predictions made by ignoring effects due to convection however convective motions do shorten the time for complete solidification because when they are driven by kinetic undercooling there is internal crystallization in addition to that occurring near the cooled upper boundary of the lava this important effect which is absent from purely conductive models predicts stratification and zonation of the lava in agreement with field observations we also examine the effect of taking into account the heat transfer to the country rock below the lava lake and determine how the evolution of the lava lake varies with the viscosity of the lava

shallow magma transport for the 2002 3 mt etna eruption inferred from thermal infrared surveys abstract the 26 october 2002 28 january 2003 eruption of mt etna volcano was characterised by lava effusion and by an uncommon explosivity along a 1 km long eruptive fissure on the southern upper flank of the volcano the intense activity promoted rapid growth of cinder cones and several effusive vents analysis of thermal images recorded throughout the eruption allowed investigation of the distribution of vents along the eruptive fissure and of the nature of explosive activity the spatial and temporal distribution of active vents revealed phases of dike intrusion expansion geometric stabilization and drainage these phases were characterised by different styles of explosive activity with a gradual transition from fire fountaining through transitional phases to mild strombolian activity and ending with non explosive lava effusion here we interpret the mechanisms of the dike emplacement and the eruptive dynamics according to changes in the eruptive style vent morphology and apparent temperature variations at vents detected through thermal imaging this is the first time that dike emplacement and eruptive activity have been tracked using a handheld thermal camera and we believe that its use was crucial to gain a detailed understanding of the eruptive event

u and th series disequilibria in coastal infill sediments from praia da rocha algarve region portugal a contribution to the study of late quaternary weathering and erosion u and th series disequilibria observed in a sequence of infill sediments from praia da rocha southern portugal were used in combination with geochemical and particle size data to investigate sediment provenance with a view to resolving the late quaternary weathering and erosion history of the algarve region and the stratigraphy of coastal karstic exposures of the faro quarteira fq formation the red infill units can be distinguished from the brown and buff units on the basis of their lower residual u and th concentrations their differing post depositional histories as revealed by u and th series disequilibria in sequentially extracted sediment phases and their greater degree of sediment processing hence the buff and brown infill units appear to be derived locally from weathering of the miocene limestone whilst the red infill may be linked to large scale mass movement of the fq formation from further inland but south of silves during the late pleistocene this sequence of events confirms a close association between the formation of karst topography and infilling by gravitational slumping debris flow and fluvial activity and hence accounts for the complex three stage sediment provenance of the infill material

loki io a periodic volcano loki is the most powerful volcano in the solar system it has been observed to be in continuous though variable activity since 1979 synthesis of more than a decade of groundbased data suggests that loki eruptions are cyclic with a 540 day period application of a simple lava cooling model to temperatures in loki patera and eruption start and end times implies that brightenings are due to a resurfacing wave propagating across the patera the data are most consistent with lava lake overturn but resurfacing by lava flows cannot be ruled out a porosity gradient in the lake crust could cause lava lake overturn to occur periodically on the timescale observed

improved remote sensing estimates of lava flow cooling a case study of the 1991 1993 mount etna eruption infrared radiance data acquired by the landsat thematic mapper tm provide information regarding the thermal state of active lavas which can be used to estimate flow surface temperatures and thus lava cooling saturation of one or both of tm s short wave infrared swir wavebands has meant however that previous studies of lava flow cooling have approximated what is almost certainly an n thermal component flow surface temperature distribution where n 1 with a single pixel integrated temperature pit we show that the high sensitivity of tm s swir wavebands to the small amount of high temperature e g 1000 c material exposed in hot fractures within the flows cooler e g 200 c surface crust results in the calculation of pits that are higher than the temperature of this crust which is usually the dominant radiative component this causes heat loss from such pixels to be overestimated we present adaptations that allow more realistic heat loss estimates to be produced using tm data by assuming that a second high temperature component contributes to the radiance measured from saturated pixels and by defining an appropriate range for the temperature of the lava crust by analyzing a suite of five tm images acquired during the 1991 1993 eruption of mount etna we present more realistic estimates of how this flow cooled as well as results that show how the flow regime of the lava evolved over time the methods we present will continue to be of use as although the next generation of high spatial resolution sensors such as the landsat 7 enhanced thematic mapper plus etm and the terra advanced space borne thermal emission and reflection radiometer aster will be less susceptible to saturation than tm the problem will still persist

lava lake surface characterization by thermal imaging erta ale volcano ethiopia the project sviluppo di sistemi di monitoraggio dipartimento di protezione civile di regione sicilia ingv catania section italy the leverhulme trust the bbc and the ethiopian air force

reactivation of stromboli s summit craters at the end of the 2007 effusive eruption detected by thermal surveys and seismicity this paper was partially supported by a grant to s c project ingv dpc paroxysm v2 03 2008 2010 funded by the istituto nazionale di geofisica e vulcanologia and by the italian civil protection

rheological properties of paraffin as an analogue material for viscous crustal deformation the rheological stratification induced by temperature variations within the crust requires analogue materials with temperature sensitive viscosity to properly simulate the change of mechanical properties with depth rheological calibration experiments on commercial paraffin wax with melting point of 53 1 c show that this material is a nonlinear fluid 1 6 n 2 1 for homologous temperatures t tm 0 70 and an approximately newtonian fluid 1 0 n 1 3 for t tm 0 70 the decrease in the stress exponent n is probably associated with the phase transition of paraffin effective viscosity values are strongly temperature dependent varying by nine orders of magnitude from 1010 to 10 pa s in the temperature range between 30 and 52 c the rheological properties of paraffin make this material useful for modelling crustal rheology and tectonic processes when linear dimensions and time scale down by a factor of 106 and 1011 respectively

mechanism of energy transfer in the lava lake of niragongo zaire 1959 1977 abstract heat and mass transfer rates were studied at the niragongo lava lake during two expeditions directed by h tazieff in 1959 and 1972 the results of this study are as follows heat is transferred to the surface of the lake by the movement of lava gas discharge is a result and not the cause of convection the chemical composition of the gases and magma has changed very little between 1959 and 1972 whereas the mass and energy outputs differ by an order of magnitude in 1977 a catastrophic explosion seems to have been caused by tectonic factors stopping the slow convection of magma under the volcano and hence reducing surface manifestations in the form of the lava lake and escaping fumarolic and magmatic gases the gas discharge was in tons day 1 5000 for h2o 11 000 for co2 1000 for so2 in 1959 and in 1972 7700 for h2o 180 000 for co2 and 23 000 for so2 these values correspond to an energy transfer of 0 9 109 w in 1959 and 16 109 w in 1972

global warming may have slowed down the deep conveyor belt of a marginal sea of the northwestern pacific japan sea weakening of the abyssal circulation conveyor belt in the japan sea during the 20th century is deduced from the decreasing trend of bottom dissolved oxygen o2 this trend indicates a shortened o2 supply caused by too inactive conveyor belt to compensate for biological o2 consumption at the bottom of the sea recent climatic changes during the winter season in the northern japan sea may play a significant role in prohibiting the formation of surface seawater dense enough to sink to the bottom it is predicted that the japan sea bottom water will become anoxic within a few hundred years as it was in the last glacial maximum

scaling of columnar joints in basalt 1 we describe field work analysis and modeling of columnar joints from the columbia river basalt group this work is focused on the regions around the grand coulee snake river and columbia gorge which form parts of this unusually homogeneous and very large sample of columnar basalt we examine in detail the scaling relationship between the column width and the size of the striae and relate these quantitatively to thermal and fracture models we found that the column radius and stria size are proportional to each other and inversely proportional to the cooling rate of the lava near a flow margin our results put observational constraints on diffusive thermal models of joint formation deeper than a few meters into a colonnade our measurements are consistent with a simple advection diffusion model of two phase convective cooling within the joints regardless of the direction of cooling this model allows an accurate comparison of igneous columnar jointing and joints due to desiccation in laboratory analog systems we also identify a new length scale in which wavy columns can appear in some colonnades the mechanisms leading to the wavy columns are likely related to those underlying similar wavy cracks in 2 d analog systems

the application of uranium series disequilibrium concepts to sediment yield determination the determination of uranium series disequilibria in fluvial environments is proposed as a method of calculating catchment mass balances the technique is based on two main principles firstly 234u is more mobile than 238u especially during the early stages of weathering secondly uranium is far more mobile than either thorium or protactinium consequently teaching during weathering results in the loss of the uranium found in the fresh rock leaving the two immobile daughters behind the ratio of uranium carried by sediment to that dissolved us uw can therefore be determined from river water and sediment isotopic activity ratios fluxes of uranium can then be calculated from average concentrations in the water and the associated sediment from which a sediment yield can be inferred the witham catchment in lincolnshire has been used to test the proposed method a us uw ratio of between 5 and 7 is determined and a sediment yield of 2 51 2 12 tonnes yr 1 km 2 is proposed although some problems concerning environmental chemistry have arisen the validity of the approach is confirmed by the close correspondence between the results obtained and those inferred by earlier workers using more conventional methods

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

monitoring the cooling of the 1959 kīlauea iki lava lake using surface magnetic measurements lava lakes can be considered as proxies for small magma chambers offering a unique opportunity to investigate magma evolution and solidification repeated magnetic ground surveys over more than 50 years each show a large vertical magnetic intensity anomaly associated with k lauea iki crater partly filled with a lava lake during the 1959 eruption of k lauea volcano island of hawai i the magnetic field values recorded across the k lauea iki crater floor and the cooling lava lake below result from three simple effects the static remnant magnetization of the rocks forming the steep crater walls the solidifying lava lake crust and the hot but shrinking paramagnetic non magnetic lens 540 c we calculate 2d magnetic models to reconstruct the temporal evolution of the geometry of this non magnetic body its depth below the surface and its thickness our results are in good agreement with the theoretical increase in thickness of the solidifying crust with time using the 2d magnetic models and the theoretical curve for crustal growth over a lava lake we estimate that the former lava lake will be totally cooled below the curie temperature in about 20 years this study shows the potential of magnetic methods for detecting and monitoring magmatic intrusions at various scales

235u fission tracks and238u series disequilibria as a means to study recent mobilization of uranium in archaean pyritic conglomerates uranium transport in archaean sediments was investigated by means of two carefully selected suites of variably weathered sediment samples from different localities of the pongola supergroup kaapvaal craton south africa u remobilization on a micron to meter scale was analyzed using u fission track micromapping and spectrometry bulk measurements these studies were supported by ore microscopy neutron activation analysis and spectrometry by combining particle track technique and spectrometry detailed information is obtained on the u transport history of weathered surface samples a simple model of u redistribution processes in geologic systems based on238u series disequilibria is developed and applied to the samples investigated some implications for radiometric field methods are discussed

the occurrence vesiculation and solidification of dense blue glassy pahoehoe dense blue glassy pahoehoe occurs on the lower kalapana flow field of hawaii as limited breakouts at the base of tumuli and pressure rises or in localized depressions dense blue glassy pahoehoe differs from the more abundant spongy pahoehoe in that it has a distinctive silvery blue color a poorly vesiculated glassy outer selvage and lower extrusion temperature 10 c cooler the color of blue glassy pahoehoe may be attributed to the concentration of iron and magnesium at the surface whereas the golden color of the spongy pahoehoe is possibly the result of fluorine enrichment the outer margin of the dense pahoehoe consists of three layers developed in response to an increased cooling rate toward the surface the outer glass selvage is less than 1 cm thick containing minor amounts of chromite olivine plagioclase and augite inside the glassy rind is a 5 mm thick transition zone characterized by increasing numbers and sizes of quenched plagioclase crystals and augite clusters the interior of dense blue glassy pahoehoe is largely crystalline crystal size distribution csd theory demonstrates that the formation and textures of plagioclase pyroxene and oxides are related to the cooling rates growth rates g and nucleation rates j present in each layer of the dense pahoehoe in contrast to the outer selvage the crystalline interior typically contains numerous large coalesced vesicles as compared to the evenly vesiculated spongy pahoehoe the enigmatic contrast between the poorly vesicular outer glassy selvage and the vesicular interior has been attributed to both lower and higher vapor contents of the dense pahoehoe the higher density lower extrusion temperatures degassed outer glassy selvage well developed crystalline interior and fluorine deficient surface of dense blue glassy as compared to spongy pahoehoe indicate that blue glassy pahoehoe was stagnant long enough to exsolve considerable vapor in the lava tube system before extrusion

lava lakes on io observations of io s volcanic activity from galileo nims during the 2001 fly bys abstract galileo s near infrared mapping spectrometer nims obtained its final observations of io during the spacecraft s fly bys in august i31 and october 2001 i32 we present a summary of the observations and results from these last two fly bys focusing on the distribution of thermal emission from io s many volcanic regions that give insights into the eruption styles of individual hot spots we include a compilation of hot spot data obtained from galileo voyager and ground based observations at least 152 active volcanic centers are now known on io 104 of which were discovered or confirmed by galileo observations including 23 from the i31 and i32 io fly by observations presented here we modify the classification scheme of keszthelyi et al 2001 j geophys res 106 e12 33 025 33 052 of io eruption styles to include three primary types promethean lava flow fields emplaced as compound pahoehoe flows with small plumes 200 km high plumes and rapidly emplaced flow fields and a new style we call lokian that includes all eruptions confined within paterae with or without associated plume eruptions thermal maps of active paterae from nims data reveal hot edges that are characteristic of lava lakes comparisons with terrestrial analogs show that io s lava lakes have thermal properties consistent with relatively inactive lava lakes the majority of activity on io based on locations and longevity of hot spots appears to be of this third type this finding has implications for how io is being resurfaced as our results imply that eruptions of lava are predominantly confined within paterae thus making it unlikely that resurfacing is done primarily by extensive lava flows our conclusion is consistent with the findings of geissler et al 2004 icarus this issue that plume eruptions and deposits rather than the eruption of copious amounts of effusive lavas are responsible for io s high resurfacing rates the origin and longevity of islands within ionian lava lakes remains enigmatic

the thermal signature of volcanic eruptions on io and earth abstract we investigate a spectrum based technique to identify the style of active volcanic eruptions on jupiter s moon io thermal remote sensing of io has had to rely primarily on low spatial resolution data similar to low spatial resolution satellite data applied to detecting and charting the temporal evolution of terrestrial hot spots these terrestrial analyses use data from sensors designed to monitor the weather and sea surface temperature on io such low spatial resolution data are used to classify eruption styles modes of emplacement by means of several criteria related to the temporal evolution of the infrared spectrum associated with the eruptive activity at each hot spot which we term thermal signature we find that the ratio of the emission at 2 and 5 m and how this ratio changes with time is often diagnostic of eruption style even in low spatial resolution data tests using thermal data for terrestrial ground truth cases show that our classification system is valid on earth the results of our analysis can be used to aid in the design of future space based instruments that can be used for volcano monitoring on io as well as earth

stability of lava lakes a physical model of a generic lava lake system is developed we derive the requisite conditions for the existence of an equilibrium lava lake in which magmastatic pressure at the base of the conduit balances the pressure in the underlying magmatic reservoir the stability of this lava lake system is tested by investigating the response of the system to perturbation we develop a graphical method based on the system s pressure depth profile to predict the subsequent behaviour of the system despite the simplicity of the modelled system we find a broad behavioural spectrum initially the rise of bubbles through the magma is ignored in this case both stable long lived lava lakes and unstable lakes that are prone to sudden draining are predicted the stability of the system is shown to be controlled by lake conduit geometry the solubility and gas expansion laws and the magma s volatile content we show that an unstable lake must collapse to a new stable equilibrium subsequent recharge of the system by for example conduit overturn would promote a return to the original equilibrium giving rise to cyclic behaviour such a mechanism is consistent with lava lake behaviour during the 1983 1984 pu u o o eruption of kilauea when the rise of bubbles through the magma is considered our model predicts that stable lakes must drain over time we therefore deduce that persistently degassing stable lava lakes such as those observed at mt erebus antarctica and mauna ulu kilauea hawaii must have an effective conduit convection mechanism or an exogenous supply of bubbles from depth

crustal deformation at the sumatran subduction zone revealed by coral rings analyses of coral rings grown in the interval 1970 1997 reveal a geographically distinct pattern of interseismic uplift off sumatra s western coast at distances less than 110 km from the sumatran trench coral reefs are submerging as fast as 5 mm y at 130 and 180 km distance from the trench they are emerging at similar rates we suggest that a locked or partially locked patch located above 30 km depth on the upper surface of the subducting oceanic plate generates this pattern

cooling rate of an active hawaiian lava flow from nighttime spectroradiometer measurements a narrow band spectroradiometer has been used to make nighttime measurements of the phase 50 eruption of pu u o o on the east rift zone of kilauea volcano hawaii on february 19 1992 a ger spectroradiometer was used to determine the cooling rate of an active lava flow this instrument collects 12 bit data between 0 35 to 3 0 m at a spectral resolution of 1 5 nm thirteen spectra of a single area on a pahoehoe flow field were collected over a 59 minute period 21 27 22 26 hst from which the cooling of the lava surface has been investigated a two component thermal mixing model flynn 1992 applied to data for the flow immediately on emplacement gave a best fit crustal temperature of 768 c a hot component at 1150 c and a hot radiating area of 3 6 of the total area over a 52 minute period within the time interval between flow resurfacings the lava flow crust cooled by 358 c to 410 c at a rate that was as high as 15 c min 1 our observations have significance both for satellite observations of active volcanoes and for numerical models of the cooling of lava flows during their emplacement

uranium series disequilibrium in river sediments and waters the significance of anomalous activity ratios abstract samples of river water suspended and bottom sediments from the fenland catchment system draining into the wash u k have been analysed for the longer lived u th series radionuclides 238u 234u 230th and 232th the aim of this work was to assess the effects of open system phase transfer on the u series disequilibria observed in the river waters and sediments and to investigate the controls exerted on this phase transfer by the hydrological regime two important aspects of the u series radionuclide mobilisation in this modern river system have been observed 1 u series radionuclides are in a continuous state of flux between river sediments and river water and 2 u sorption on sediment particles is seasonably variable sequential extraction of whole sediments revealed that the u series isotopic characteristics of the ion exchangeable organic bound carbonate amorphous fe mn oxyhydroxides and crystalline fe mn oxides are controlled to a significant degree by the acquisition of u isotopes from the aqueous phase during summer when surface run off and river discharges are generally low the u isotope acquisition by sediment particles results in anomalously high234u 238u activity ratios 1 this is of importance for studies which rely upon the isotopic and elemental separation of u series radionuclides in the weathering system i e mass balance weathering rate and sediment yield assessments

total grain size distribution of an intense hawaiian fountaining event case study of the 1959 kīlauea iki eruption the 1959 eruption of k lauea iki on the island of hawai i is a principal example of powerful hawaiian fountaining over 36 days including repose periods 16 fountaining episodes created a small cone a downwind tephra blanket of approximately 0 003 km3 and a lava lake of about 0 04 km3 volume during the explosive activity the maximum fountain heights reached 600 m based on a dataset of more than 450 tephra grain size samples we present both a total grain size distribution tgsd of the entire downwind tephra deposit and also tgsds for two eruptive subunits the opening and the closing stages the opening stage was characterized by persistent fountaining over a period of 8 days with fountain heights averaging 100 m in contrast the closing stage was characterized by two short hours long but powerful fountaining episodes up to 600 m the significantly different fountaining intensities are reflected in the characteristics of the tgsds for the closing stages we link bimodality of tgsds to periods of simultaneous deposition of ballistics and fallout from the convective cloud both of which are a function of the maximum fountain height the 1959 k lauea iki case study presents a well constrained set of tgsd data linked with hawaiian style fountaining of two contrasting intensities and can be used as a valuable reference point for eruption source parameters in future modeling of pyroclast dispersal during hawaiian fountaining eruptions

conclusion recommendations and findings of the red seed working group red seed stands for risk evaluation detection and simulation during effusive eruption disasters and combines stakeholders from the remote sensing modelling and response communities with experience in tracking volcanic effusive events the group first met during a three day long workshop held in clermont ferrand france between 28 and 30 may 2013 during each day presentations were given reviewing the state of the art in terms of a volcano hot spot detection and parameterization b operational satellite based hot spot detection systems c lava flow modelling and d response protocols during effusive crises at the end of each presentation set the four groups retreated to discuss and report on requirements for a truly integrated and operational response that satisfactorily combines remote sensors modellers and responders during an effusive crisis the results of collating the final reports and follow up discussions that have been on going since the workshop are given here we can reduce our discussions to four main findings 1 hot spot detection tools are operational and capable of providing effusive eruption onset notice within 15 min 2 spectral radiance metrics can also be provided with high degrees of confidence however if we are to achieve a truly global system more local receiving stations need to be installed with hot spot detection and data processing modules running on site and in real time 3 models are operational but need real time input of reliable time averaged discharge rate data and regular updates of digital elevation models if they are to be effective the latter can be provided by the radar photogrammetry community 4 information needs to be provided in an agreed and standard format following an ensemble approach and using models that have been validated and recognized as trustworthy by the responding authorities all of this requires a sophisticated and centralized data collection distribution and reporting hub that is based on a philosophy of joint ownership and mutual trust while the next chapter carries out an exercise to explore the viability of the last point the detailed recommendations behind these findings are detailed here

a laboratory analog study of the surface morphology of lava flows extruded from point and line sources abstract in laboratory experiments designed to model lava flow processes liquid polyethylene glycol wax is forced through either a small hole or a long narrow slit onto the base of a tank of cold water where it spreads laterally while cooling and solidifying at its surface we observe the surface structure of the flow and its dependence on the flow rate thermal conditions and basal roughness in each case solidification of a crust during spreading gives rise to a number of different surface morphologies each of which forms under a restricted range of conditions the dominant morphologies referred to as pillows rifts transverse folds and marginal levees correspond to features observed on natural lava flows results for radial spreading over a rough base and for spreading in two directions from the line source over both smooth and rough bases complement those reported earlier for radial spreading of solidifying wax from a point source on a smooth base together they indicate a robust dependence of morphology on the distance from the vent at which solid crust begins to form this distance is in turn determined by the extrusion rate the rheology of the liquid wax or magma the reduced gravity the magnitude of the surface heat flux and the amount of cooling required to solidify the flow surface the results also indicate factors influencing the distribution of crust and its deformation and may provide a means by which observations of surface morphology can be used to place constraints on the emplacement conditions of lava flows

the geochemistry of water near a surficial organic rich uranium deposit northeastern washington state u s a abstract the chemistry of three stream three spring and six near surface waters in the vicinity of a holocene organic rich uranium deposit is described with particular emphasis on the chemistry of u results characterize the solution behavior of uranium as u bearing water interacts with relatively undecomposed surficial organic matter of the measured major and trace chemical species only u is consistently highly enriched 17 318 ppb relative to reported values for regional waters or to literature values for waters in largely granitic terrains r mode factor analysis of the chemical data suggests that most u is present in a soluble form but that some u is also associated with fine suspended particulates of clay organic matter or hydrous oxides calculations that apply thermodynamic data to predict u speciation in solution indicate the relative importance of uranyl carbonate and uranyl phosphate complexes analysis of more finely filtered samples 0 05 m vs 0 45 m and direct radiographic observations using fission track detectors suspended in the waters indicate the presence of some uraniferous particulate matter application of existing thermodynamic data for uranous and uranyl bearing minerals indicates that all waters are undersaturated with u minerals as long as ambient eh 0 1 v if coexisting surface and near surface waters are sufficiently oxidizing initial fixation of u in the deposit should be by a mechanism of adsorption alternatively more reducing conditions may prevail in deeper pore waters of the organic rich host sediments perhaps leading to direct precipitation or diagenetic formation of u4 minerals a 234 u 238 u alpha activity ratio of 1 08 0 02 in a spring issuing from a hillslope above the deposit suggests a relatively soluble source of u in contrast higher activity ratios of 234 u 238 u 1 3 in waters in contact with the uraniferous valley fill sediments suggest differences in the nature of interaction between groundwater and the local u rich source rocks

gas driven lava lake fluctuations at erta ale volcano ethiopia revealed by modis measurements the long lived lava lake of erta ale volcano ethiopia is remotely monitored by moderate resolution imaging spectroradiometers modis installed on satellites the normalised thermal index nti wright et al remote sens environ 82 135 155 2002 is shown to be proportional to the volume of the lava lake based on visual observations the lava lake s variable level can be plausibly related to a stable foam i e a mixture composed of densely packed non coalescing bubbles in suspension within a liquid this foam is trapped at the top of the magma reservoir and its thickness changes in response to the gas flux feeding the foam being successively turned on and off the temporal evolution of the foam thickness and the resulting variation of the volume of the lava lake is calculated numerically by assuming that the gas flux feeding the foam initially constant and homogeneous since december 9 2002 is suddenly stopped on december 13 2002 and not restarted before may 2003 the best fit between the theoretical foam thickness and the level of the lava lake deduced from the nti provides an estimate of both the reservoir radius 155 170 m and the gas flux feeding the foam 5 5 10 3 7 2 10 3 m 3 s 1 when existing this is in agreement with previous estimates from acoustic measurements bouche et al earth planet sci lett 295 37 48 2010 the very good agreement between the theoretical foam thickness and that deduced from modis data shows for the first time the existence of a regime based on the behaviour of a stable foam whose spreading towards the conduit wide conduit condition can explain the long lived activity our predictive model which links the gas flux at the vent to the foam spreading could potentially be used on any volcano with a long lived activity the underlying gas flux and the horizontal surface area of the magma reservoir can then be deduced by combining modelling to continuous measurements of gas flux the lava lake when high often shows regular rise and fall of its level we have recognised a minimum of 26 very well marked cycles between january 2001 and december 13 2002 corresponding to a typical return time of 10 8 2 3 days and a gas volume of 8 3 105 2 0 105 m 3 this corresponds to a gas volume fraction in the reservoir equal to 0 023 0 063 the yearly gas flux estimated between december 13 2002 and september 27 2004 varies between 2 3 10 6 and 5 9 10 6 m 3 s 1 at the depth of the reservoir the long time series provided by infra red sensors mounted on satellites could be used on any persistent volcano to detect potential periodic variations in the level of lava lakes or lava columns providing that the vent has a funnel shape as often and is sufficiently large

excess bottom222rn profiles and their implications in the northwestern pacific ocean abstract vertical profiles of excess bottom 222 rn and potential temperature were measured at 23 stations in the northwestern pacific ocean the rn profiles were classified into the following three types quasi exponential type e benthic boundary layer type b and horizontally disturbed type h the ratio among types e b and h was approximately 2 3 1 an apparent vertical eddy diffusivity k was calculated by applying a one dimensional diffusion model to the rn profiles of types e and b type e had k values ranging from 15 to 180 cm 2 s 1 average 70 cm 2 s 1 as to type b k values for the benthic boundary layer 4 5 260 cm 2 s 1 average 120 cm 2 s 1 were always more than an order of magnitude larger than those for the upper layer 0 2 35 cm 2 s 1 average 7 cm 2 s 1 indicating more active vertical mixing in the benthic boundary layer than in the upper layer rn profiles were measured in regions where the bottom topography is known it was verified that the occurrence of type h related closely with local bottom topographic features accompanied by lateral transient supply of rn rich or rn poor water a couple of rn profiles at the same location measured at time intervals of several years were compared with each other for three locations the general characteristics of rn profiles were shown to remain unaltered with time while the fine structure of rn profiles may have short term variations caused by local bottom topography and fluctuations of bottom current as indicated in type h

multiparametric study of the february april 2013 paroxysmal phase of mt etna new south east crater european fp7 med suv mediterranean supersite volcanoes grant number 308665 european research council european fp7 fp 2007 2013 erc grant number 279802 sigma sistema integrato di sensori in ambiente cloud per la gestione multirischio avanzata

multi instrument remote and in situ observations of the erebus volcano antarctica lava lake in 2005 a comparison with the pele lava lake on the jovian moon io abstract the stable persistent active lava lake at erebus volcano ross island antarctica provides an excellent thermal target for analysis of spacecraft observations and for testing new technology in the austral summer of 2005 visible and infrared observations of the erebus lava lake were obtained with sensors on three space vehicles terra aster modis aqua modis and eo 1 hyperion ali contemporaneous ground based observations were obtained with hand held infrared cameras this allowed a quantitative comparison of the thermal data obtained from different instruments and of the analytical techniques used to analyze the data both with and without the constraints imposed by ground truth from the thermal camera data in december 2005 the main erebus lava lake ray lake had an area of 820 m2 surface colour temperatures ranged from 575 k to 1090 k with a broad peak in the distribution from 730 k to 850 k total heat loss was estimated at 23 5 mw the flux density was 29 kw m 2 mass flux was estimated at 64 to 93 kg s 1 the best correlation between thermal emission and emitting area was obtained with aster which has the best combination of spatial resolution and wavelength coverage especially in the thermal infrared the high surface temperature of the lava lake means that hyperion data are for the most part saturated uncertainties introduced by the need to remove incident sunlight cause the thermal emission from the hyperion data to be a factor of about two greater than that measured by hand held thermal camera modis also over estimated thermal output from the lava lake by the same factor of two because it was detecting reflected sunlight from the rest of the pixel area the measurement of the detailed temperature distribution on the surface of an active terrestrial lava lake will allow testing of thermal emission models used to interpret remote sensing data of volcanism on io where no such ground truth exists although the erebus lava lake is four orders of magnitude smaller than the lava lake at pele on io the shape of the integrated thermal emission spectra are similar thermal emission from this style of effusive volcanism appears to be invariant excess thermal emission in most pele spectra compared to erebus at short wavelengths

holocene alluviation in the algarve southern portugal the case for an anthropogenic cause abstract finding a causal mechanism to account for observed phases of valley alluviation in the mediterranean region and southern europe during the holocene has been a subject of debate for more than 20 years three possible causes have been suggested regional climatic change anthropogenic induced erosion and the crossing of intrinsic thresholds within fluvial systems so that deposition rather than erosion is favoured in this paper we report investigations carried out in the algarve region southern portugal where past research is interpreted as suggesting a climatic cause mapping and sedimentological investigations of holocene sediments within three major valleys in this region are reported together with the association of these deposits with artifacts a roman moorish mill and bands of charcoal chemical as well as physical sedimentological interpretation was carried out on the deposits we also report the results of a detailed investigation and reconstruction of the land use and settlement history of the area and show that episodes of valley alluviation coincide in time with phases of intensive agriculture and clearance within the catchments of these valleys whereas episodes of valley erosion coincide with episodes of relative stability whilst recognizing that temporal correlations are not necessarily causal we argue that in this area anthropogenic forcing of phases of holocene alluviation is the preferred mechanism

deep flow field in the japan east sea as deduced from direct current measurements abstract the mean flows and variability in the abyssal japan east sea are investigated on the basis of direct current observation data the distribution of the mean flow vectors indicates relatively strong cyclonic circulations along the basin periphery and sluggish flows in the interior region strong mean flows of faster than 6 0 cm s 1 are found at the western edge in the yamato and ulleung basins considered to be the western boundary currents in each basin the similarity between the distributions of the mean flow vectors in the upper 400 1000 m and lower layers 1000 m bottom indicates common circulation patterns throughout the water column of the proper water progressive vector diagrams show meandering curves with clockwise and anticlockwise turns due to the passing of mesoscale eddies since a dominant background flow is absent in the basin interior the ratio of eddy kinetic energy to the mean flow kinetic energy reaches more than 50 in the interior region this indicates that the flows observed in the interior region are comparable to those in the basin periphery even though the mean flow is generally weak spectral analysis has revealed that tidal fluctuations are prevailing in the ulleung basin while they are absent in the yamato and japan basins though the inertial oscillation is dominant in all of the basins this indicates that the tidal energy from the east china sea is confined within the ulleung basin suggesting the barrier effect of the yamato rise and the oki spur significant energy peaks are also found in the 2 5 and 5 10 day period bands in the yamato basin the former variation represents the shelf wave activity trapped on the basin edge and the latter is due to eddy migrations associated with the tsushima current

effects of a volcanic plume on thermal imaging data ground based thermal imaging is becoming an increasingly important tool for volcano surveillance however the impact of volcanic plumes on quantitative measurements of surface temperature has not been previously evaluated here we use a radiative transfer model to simulate gas primarily h2o and so2 and aerosol absorptions over the path between a thermal camera and a heat source on stromboli volcano italy a ftir spectrometer was used to quantify path amounts of gases likely to be encountered when making thermal measurements of the active craters we find that when using a camera sensitive from 7 5 to 13 mu m underestimates of similar to 400 k may be produced when viewing a source with an actual temperature of 1200 k cameras that operate between 3 and 5 mu m are somewhat less susceptible to these errors

io loki patera as a magma sea 1 we develop a physical model for loki patera as a magma sea we calculate the total volume of magma moving through the loki patera volcanic system every resurfacing cycle 540 days and the resulting variation in thermal emission the rate of magma solidification at times reaches 3 106 kg s 1 with a total solidified volume averaging 100 km3 yr 1 a simulation of gas physical chemistry evolution yields the crust porosity profile and the timescale when it will become dense enough to founder in a manner consistent with observations the loki patera surface temperature distribution shows that different areas are at different life cycle stages on a regional scale however there can be coordinated activity indicated by the wave of thermal change which progresses from loki patera s sw quadrant toward the ne at a rate of 1 km d 1 using the observed surface temperature distribution we test several mechanisms for resurfacing loki patera finding that resurfacing with lava flows is not realistic only the crustal foundering process is consistent with observations these tests also discovered that sinking crust has a heat deficit which promotes the solidification of additional magma onto the sinking plate bulking up in the limiting case the mass of sinking material can increase to a mass of 3 times that of the foundering plate with all this solid matter sinking there is a compensating upward motion in the liquid magma this can be in excess of 2 m yr 1 in this manner solid liquid convection is occurring in the sea

radiative temperature measurements at kupaianaha lava lake kilauea volcano hawaii field spectroradiometer data in the wavelength range of 0 4 2 5 m and spectral resolution of 1 5 nm have been used to compute the radiative temperature of the surface of kupaianaha lava lake kilauea volcano hawaii two sets of observations a total of 120 spectra were made on october 12 1987 and january 23 1988 when the lava lake was in a period of active overturning the area of the surface for which temperatures were measured was 0 23 0 55 m2 two numerical models of two and three components have been used to match the measured radiant flux ratios and to describe the surface of the lava pond in terms of radiant area and temperature three stages of activity on the lake surface are identified stage 1 characterized by magma fountaining and overturning events exhibited the hottest crustal temperatures 180 572 c and the largest fractional hot areas 10 3 stage 1 average flux densities were 2 2 104 w m2 the highest recorded for the three stages of activity on either day the largest radiative area of fresh magma was 29 at 1100 c while cooling from magmatic temperatures to newly formed crust at 790 c took place in a matter of seconds stage 2 marked by rifting events between plates of crust exhibited crustal temperatures between 100 and 340 c with fractional hot areas at least an order of magnitude lower than those found for stage 1 average flux densities calculated for three examples of stage 2 activity were 5 3 103 w m2 stage 3 which was quiescent periods when the lake was covered by a thick crust dominated the activity of the lake both temporally and spatially over 90 of the time the characteristic crustal temperature of stage 3 was 80 345 c with most solutions near 200 300 c and fractional hot areas of 10 5 of the viewing area average flux densities for stage 3 were 4 9 103 w m2 for many stage 3 examples a two component model was sufficient to describe the spectral data however for almost all of the stage 1 and 2 examples and the remainder of the stage 3 examples a three component model was required these determinations of lava temperature and radiant area have relevance for satellite and airborne measurements of the thermal characteristics of active volcanoes and indicate that temporal variability of the thermal output of lava lakes occurs on the time scale of seconds to minutes

the effect of multiple pre existing weaknesses on formation and evolution of faults in extended sandbox models abstract high resolution three dimensional seismic data show that fault distribution and evolution in rift basins can be very complicated and inconsistent with the classic model of fault formation and propagation fault development in the presence of multiple pre existing weaknesses is still not clearly studied trying to understand the role of multiple pre existing weaknesses in sand models two series of experiments were prepared in the first series of models the mechanical properties of pre existing weaknesses were the same but their orientations were different whereas in the second series of models both mechanical properties and orientations were different the basic characteristics of fault formation and evolution in a rift basin revealed by the models are as follows 1 weakness reactivated faults faults that formed directly along and above the pre existing weaknesses and weakness related faults faults which are not located above the pre existing weaknesses but have similar orientation form much earlier than weakness unrelated faults the order of formation of different weakness reactivated faults is determined by the relative reactivation tendency factors fa of the weaknesses 2 weakness reactivated faults and weakness related faults develop mainly along or parallel to pre existing weaknesses in contrast weakness unrelated faults develop nearly perpendicular to the extension direction 3 a complicated fault system can form during a single extension phase in the presence of multiple pre existing weaknesses and 4 the mode of fault formation and propagation and the increase in length and number of faults have close ties to the nature of pre existing weaknesses fault displacement and length do not have a power law relationship for the majority of faults and there is no unique relationship for different kinds of faults in addition to providing new insights to the formation of complex fault systems the experiment results presented here could be reasonably explained using the reactivation tendency theory they can also be applied to the complicated fault system in rift basin

a frozen record of density driven crustal overturn in lava lakes the example of kīlauea iki 1959 lava lakes are found at basaltic volcanoes on earth and other planetary bodies density driven crustal foundering leading to surface renewal occurs repeatedly throughout the life of a lava lake this process has been observed and described in a qualitative sense but due to dangerous conditions no data has been acquired to evaluate the densities of the units involved k lauea iki pit crater in hawai i houses a lava lake erupted during a 2 month period in 1959 part of the surface of the k lauea iki lake now preserves the frozen record of a final incomplete crustal overturn cycle we mapped this region and sampled portions of the foundering crust as well as overriding and underlying lava to constrain the density of the units involved in the overturn process overturn is driven by the advance of a flow front of fresh low density lava over an older higher density surface crust the advance of the front causes the older crust to break up founder and dive downwards into the lake to expose new hot low density lava we find density differences of 200 to 740 kg m3 between the foundering crust and over riding and under lying lava respectively in this case crustal overturn is driven by large density differences between the foundering and resurfacing units these differences lead inevitably to frequent crustal renewal simple density differences between the surface crust and underlying lake lava make the upper layers of the lake highly unstable

hawaiian fissure fountains 1 decoding deposits episode 1 of the 1969 1974 mauna ulu eruption deposits from episode 1 of the 1969 1974 mauna ulu eruption of k lauea provide an exceptional opportunity to study processes of low intensity hawaiian fissure fountains episode 1 lava flows passed through dense forest that had little impact on flow dynamics in contrast the pattern of spatter preservation was strongly influenced by the forest through the formation of tree molds and the preexisting topography a low near continuous spatter rampart is present upwind and upslope on the north side of the fissure most of the pyroclastic products however fell downwind to the south of the fissure but little was preserved due to two processes 1 incorporation of proximal spatter in rheomorphic lava flows 10 20 m from the vents and 2 the downslope transport of cooler spatter falling on top of these flows beyond 20 m from vent the lava flow field itself shows a complex history initially discharge from the fissure exceeded the transport capacity of the southern drainage pathways and lava ponded dynamically to a maximum height of 4 m for 40 120 min until fountains began to decline during declining discharge lava flowed both southward away from the fissure and increasingly back into the vents there is a clear lava shed or delineation between where lava drained northwards back into the fissure and where it continued flowing to the south the 1969 deposits suggest that care is needed when products of less well documented eruptions are analyzed as postdepositional transport of spatter may preclude the formation of classic paired symmetrical ramparts

pleistocene and holocene geomorphological development in the algarve southern portugal abstract a detailed chronological framework for pleistocene and holocene geomorphology and landscape evolution in the algarve is proposed with regards to the pleistocene attention has focused on the origin dating and stratigraphy of the ludo formation subsuming the classifications of earlier writers it is now proposed that during the pliocene a marine transgression occurred across a tectonically controlled basin that was constrained by the mountains of the algarve interior to the north fluvial sands were then deposited in a regressive phase during the late pliocene early pleistocene while braided streams operating under semi arid conditions subsequently laid down sands and gravels in the middle and upper pleistocene lying unconformably over the ludo formation is an alluvial deposit odiaxere gravels and loule sands of late pleistocene early holocene date that is found within the river valleys of the algarve in the early holocene ca 10 000 ca 7000 bp and early late holocene ca 5000 ca 3000 bp the situation in the algarve was one of climatic amelioration i e warmer and wetter conditions rising sea levels vegetation colonization soil development and towards the end of this period trenching of the odiaxere gravels and loule sands from ca 3000 bp evidence is abundant that humans became important geomorphological agents either acting on their own or in combination with climatic factors from around 5000 bp conditions became dryer and between ca 3000 bp and ca 700 bp clearance of land by pre roman roman and especially islamic agricultural settlers caused widespread erosion and the deposition of extensive spreads of topsoil dominated sediment within river valleys i e the holocene terrace and in coastal estuaries a period followed up to 1900 ce when agricultural practices were less damaging to the soil erosion was reduced and the holocene terrace together with coastal and estuarine deposits was incised in the past century and under increased human pressure renewed erosion is in evidence in the interior valleys and at the coast

large scale magmatic layering in the main zone of the bushveld complex and episodic downward magma infiltration the bellevue drillcore intersects 3 km of main and upper zone cumulates in the northern limb of the bushveld complex main zone cumulates are predominately gabbronorites with localized layers of pyroxenite and anorthosite some previous workers using bulk rock major trace and isotopic compositions have suggested that the main zone crystallized predominantly from a single pulse of magma however density measurements throughout the bellevue drillcore reveal intervals that show up section increases in bulk rock density which are difficult to explain by crystallization from a single batch of magma wavelet analysis of the density data suggests that these intervals occur on length scales of 40 to 170 m thus defining a scale of layering not previously described in the bushveld complex upward increases in density in the main zone correspond to upward increases in modal pyroxene producing intervals that grade from a basal anorthosite with 5 pyroxene to gabbronorite with 30 40 pyroxene we examined the textures and mineral compositions of a 40 m thick interval showing upwardly increasing density to establish how this type of layering formed plagioclase generally forms euhedral laths while orthopyroxene is interstitial in texture and commonly envelops finer grained and embayed plagioclase grains minor interstitial clinopyroxene was the final phase to crystallize from the magma plagioclase compositions show negligible change up section average an62 with local reverse zoning at the rims of cumulus laths average increase of 2 mol in contrast interstitial orthopyroxene compositions become more primitive up section from mg 57 to mg 63 clinopyroxene similarly shows an up section increase in mg pyroxene compositions record the primary magmatic signature of the melt at the time of crystallization and are not an artefact of the trapped liquid shift effect combined the textures and decoupled mineral compositions indicate that the upward density increase is produced by the downward infiltration of noritic magma into a previously emplaced plagioclase rich crystal mush fresh noritic magma soaked down into the crystallizing anorthositic mush partially dissolving plagioclase laths and assimilating fe enriched pore melt the presence of multiple cycles showing upward increases in density in the bellevue drillcore suggests that downward magma infiltration occurred episodically during crystallization of the main zone

features of lava lake filling and draining and their implications for eruption dynamics lava lakes experience filling circulation and often drainage depending upon the style of activity and location of the vent features formed by these processes have proved difficult to document due to dangerous conditions during the eruption inaccessibility and destruction of features during lake drainage k lauea iki lava lake k lauea hawai i preserves many such features because lava ponded in a pre existing crater adjacent to the vent and eventually filled to the level of and interacted with the vent and lava fountains during repeated episodes a cyclic pattern of lake filling to above vent level followed by draining back to vent level preserved features associated with both filling and draining field investigations permit us to describe the characteristic features associated with lava lakes on length scales ranging from centimeters to hundreds of meters in a fashion analogous to descriptions of lava flows multiple vertical rinds of lava coating the lake walls formed during filling as the lake deepened and lava solidified against vertical faces drainage of the lake resulted in uneven formation of roughly horizontal lava shelves on the lakeward edge of the vertical rinds the shelves correlate with stable staggered lake stands shelves either formed as broken relict slabs of lake crust that solidified in contact with the wall or by accumulation accretion and widening at the lake surface in a dynamic lateral flow regime thin upper lava shelves reflect an initially dynamic environment in which rapid lake lowering was replaced by slower and more staggered drainage with the formation of thicker more laterally continuous shelves at all lava lakes experiencing stages of filling and draining these processes may occur and result in the formation of similar sets of features

identification of variable convective regimes at erta ale lava lake abstract during february 17 19 2002 we collected a combined thermal and seismic data set for persistent lava lake activity at erta ale volcano ethiopia these data indicate that the lake cycled between periods characterized by low 0 01 0 08 m s 1 and high 0 1 0 4 m s 1 surface velocities typically lasting tens to hundreds of minutes these periods of high and low velocity motion define periods of vigorous and sluggish convection respectively spectral analysis revealed that vigorous convection periods were characterized by high frequencies and energies in the thermal data and an increased presence of high frequency energy in the seismic data the data show that vigorous periods were characterized by formation of hot short lived plastic crusts and sluggish periods by cooler longer lived brittle crusts here the higher transit velocity across the lake surface from upwelling zones of crust formation to downwelling zones of crust destruction during the vigorous periods decreases the crust lifetime this in turn decreases the total cooling and thickening experienced by a plate of crust moving across the lake surface two scenarios can be envisaged to explain such convection cycles the first relates variable convection rates to changes in the volume flux and rheology of magma entering the lake in the second cyclic convection is set up by the generation of convective instabilities within the lake in this case cooling of a surface layer generates a slow moving viscous increasingly dense convection layer at the lake surface which is consumed and replaced during overturn

excess 222rn profiles in the bottom layer of the japan sea and their implication for bottom water dynamics abstract vertical profiles of excess radon 222 222 rn half life 3 82 days in bottom seawaters between 8 and 780 m above the seafloor were measured in the japan sea a semi closed deep marginal sea in the northwest pacific ocean all of the profiles observed at three locations two profiles in the japan basin and one in the yamato basin show curious zigzag patterns with 222 rn maxima and minima in contrast to a generally known steady state profile of 222 rn exponentially decreasing with the distance above the bottom the observed 222 rn profiles demonstrate the existence of horizontal supplies of 222 rn enriched waters in the bottom layer of the japan sea with timescales as short as the half life of 222 rn probably in relation with the interaction between bottom currents and topographic features

radiometric fingerprinting of sediments on the dutch german and danish coasts concentrations of natural radionuclides in the heavy mineral fraction of coastal sands have been shown in earlier work to be distinctly different for two regions along the dutch coast because these two regions have different source areas it was concluded that concentrations of natural radionuclides in the heavy mineral fraction of coastal sediments represent a radiometric fingerprint this fingerprint is considered to be a sensitive tool for identifying sediments of different provenance to further investigate this assumption samples were collected along the north sea and baltic coasts of the netherlands germany and denmark as an extension of the earlier work in the present investigation we find that two additional source areas may be identified using the radiometric fingerprint the four regions correspond with glacial terranes of saalian and weichsellian age and the present day watersheds of the elbe and rhine river systems

the heartbeat of the volcano the discovery of episodic activity at prometheus on io the temporal signature of thermal emission from a volcano is a valuable clue to the processes taking place both at and beneath the surface the galileo near infrared mapping spectrometer nims observed the volcano prometheus on the jovian moon io on multiple occasions between 1996 and 2002 the 5 micron m brightness of this volcano shows considerable variation from orbit to orbit prometheus exhibits increases in thermal emission that indicate episodic though non periodic effusive activity in a manner akin to the current pu u o o kupaianaha afterwards referred to as the pu u o o eruption of kilauea hawai i the volume of material erupted during one prometheus eruption episode defined as the interval from minimum thermal emission to peak and back to minimum from 6 november 1996 to 7 may 1997 is estimated to be 0 8 km3 with a peak instantaneous volumetric flux effusion rate of 140 m3 s 1 and an averaged volumetric flux eruption rate of 49 m3 s 1 these quantities are used to model subsurface structure magma storage and magma supply mechanisms and likely magma chamber depth prometheus appears to be supplied by magma from a relatively shallow magma chamber with a roof at a minimum depth of 2 3 km and a maximum depth of 14 km this is a much shallower depth range than sources of supply proposed for explosive possibly ultramafic eruptions at pillan and tvashtar as prometheus type effusive activity is widespread on io shallow magma chambers containing magma of basaltic or near basaltic composition and density may be common this analysis strengthens the analogy between prometheus and pu u o o at least in terms of eruption style even though the style of eruption appears to be similar effusive emplacement of thin insulated compound pahoehoe flows the scale of activity at prometheus greatly exceeds current activity at pu u o o in terms of volume erupted area covered and magma flux whereas the estimated magma chamber at prometheus dwarfs the pu u o o magma chamber it fits within expectations if the pu u o o chamber were scaled for the greater volumetric flux and lower gravity of io recent volumetric eruption rates derived from galileo data for prometheus were considerably smaller than the rate that produced the extensive flows formed in the 17 years between the voyager and galileo missions these smaller eruption rates coupled with the fact that flows are not expanding laterally may mean that the immediate heat source that generates the prometheus plume is simultaneously running out of available volatiles and the thermal energy that drives mobilization of volatiles this raises the question of whether the current prometheus eruption is in its last throes

infrared monitoring of volcanoes by satellite sensors on future satellite platforms will be used routinely for volcano monitoring with infrared channels offering the potential to detect and measure temperatures of features such as lava bodies and fumarole fields this is possible even though the surface temperature distributions associated with such phenomena are typically inhomogeneous at the pixel scale so long as simplifying assumptions can be made to test the applicability of the technique we have carried out field studies of a range of volcanic thermal manifestations using portable infrared thermometers rock surface temperatures around fumarolic vents exhibit greater stability with time than those associated with actively degassing lava bodies but in both cases volcanogenic fumes can significantly attenuate the emitted infrared radiation the scale of the temporal variability at a given wavelength dictates the quantitative value of isolated satellite 9snapshots9 if more spectral channels in the infrared were available on remote sensing platforms then more components of the surface temperature distribution could be extracted from the data imaging spectrometry offers the greatest flexibility although data processing including correction for atmospheric effects would present difficulties

thorium uranium disequilibrium dating of late quaternary ferruginous concretions and rinds radioactive ferruginous nodules from the alligator rivers uranium province northern territory australia were systematically examined by optical microscopy xrd alpha and fission track autoradiography and analysed for u th ra and major stable elements correlation of autoradiographs with microscopic structure and analyses of selective extractions confirmed that u and th were strongly associated with fe oxides fission track autoradiography showed no concentration gradient evidence for postdepositional leaching of uranium strong acid leaching studies showed that irreversibly adsorbed u and authigenic 234u and 230th but not 226ra are quantitatively retained by accumulated oxide oxyhydroxide correlation of the groundwater activity ratio with oxidic 234u 238u activity ratios indicated the latter was radiogenically consistent with oxidic 230th 234u activity ratios 1 dense accumulated fe mn oxide matrices are apparently capable of forming radiogenic closed systems in respect of the 230u 234u 230th decay set 234u 238u and 230th 234u activity ratios were used to derive similar mean ages of rinds for four nodules in the same horizon th u ages were also determined using a th index detrital correction method previously used for impure carbonates of pedogenic fe mn accumulations having background concentrations of u and th from other locations in australia these ages were compared with tl and 14c ages of the host sediments the comparisions suggest that th u dating could be used to age indurated layers of fe mn oxides in soil horizons 350 ka old

uranium isotopes in rivers estuaries and adjacent coastal sediments of western india their weathering transport and oceanic budget the two major river systems on the west coast of india narbada and tapti their estuaries and the coastal arabian sea sediments have been extensively studied for their uranium concentrations and 238u238u activity ratios the 238u concentrations in the aqueous phase of these river systems exhibit a strong positive correlation with the sum of the major cations na k mg ca and with the hco3 ion contents the abundance ratio of dissolved u to the sum of the major cations in these waters is similar to their ratio in typical crustal rocks these findings lead us to conclude that 238u is brought into the aqueous phase along with major cations and bicarbonate the strong positive correlation between 238u and total dissolved salts for selected rivers of the world yield an annual dissolved 238u flux of 0 88 1010g yr to the oceans a value very similar to its removal rate from the oceans 1 05 1010g yr estimated based on its correlation with hco3 contents of rivers in the estuaries both 238u and its great grand daughter 234u behave conservatively beyond chlorosities 0 14 g l these data confirm our earlier findings in other indian estuaries the behavior of uranium isotopes in the chlorosity zone 0 02 0 14 g l was studied in the narbada estuary in some detail the results though not conclusive seem to indicate a minor removal of these isotopes in this region reexamination of the results for the gironde and zaire estuaries martin et al 1978a and b also appear to confirm the conservative behavior of u isotopes in unpolluted estuaries it is borne out from all the available data that estuaries beyond 0 14 g l chlorosities act neither as a sink nor as a source for uranium isotopes the behavior in the low chlorosity zones warrants further detailed investigation a review of the uranium isotope measurements in river waters yield a discharge weighted average 238u concentration of 0 22 g l with a 234u238u activity ratio of 1 20 0 06ismissing the residence time of uranium isotopes in the oceans estimated from the 238u concentration and the 234u238u a r of the rivers yield conflicting results the material balance of uranium isotopes in the marine environment still remains a paradox if the disparity between the results is real then an additional 234u flux of about 0 25 dpm cm2 103 yr into the oceans about 20 of its river supply is necessitated

formation of bands and ridges on europa by cyclic deformation insights from analogue wax experiments 1 we perform a set of analogue wax experiments aimed at understanding the processes and conditions that lead to lineament formation on europa we heat a layer of wax from below and cool it from above so that a solid layer of wax forms above a molten layer simulating either the liquid ocean or the actively convecting part of the ice shell the solid layer of wax is then deformed periodically simulating the cyclic strain caused by tides or by the satellite s nonsynchronous rotation we find that the formation and morphology of lineaments that develop in the solid wax layer are governed by two main dimensionless parameters the ratio of the cooling timescale for the solid layer to the deformation timescale and the dilation quotient which is defined as the magnitude of net extension during one cycle of deformation divided by the amplitude of the periodic deformation for 1 features form that qualitatively resemble bands and ridge complexes on europa we conclude that diurnal tides may be responsible for the formation of bands on europa if the conducting layer of ice is a few hundred meters thick and is underlain by a convecting layer of ice features resembling double ridges can form if the ice shell has a thickness of a few kilometers and periodic strains are caused by europa s nonsynchronous rotation

what can crystal size distributions and olivine compositions tell us about magma solidification processes inside kilauea iki lava lake hawaii abstract lava lakes offer the opportunity to investigate magma solidification and can be considered as a proxy for small magma chambers here we present olivine compositions and crystal size distributions csds from scoria and drill core samples from kilauea iki lava lake which formed during the 1959 eruption of kilauea volcano hawaii three chemically distinct olivine populations were distinguished in the basis of their forsterite fo content 1 a high fo population fo86 90 2 an intermediate fo population fo78 82 and 3 a minor low fo population fo74 78 populations 1 and 2 both have deformed and undeformed crystals the third population may be the result of rejuvenation olivine in the lower 60 m of lake has a less fo rich composition and more crystals are deformed the csd analysis yields estimates of the average olivine residence time 1 60 years the shape of the olivine csds is fairly uniform with respect to depth curved csds are considered to be evidence of hybrid populations partly or totally involving crystal or magma mixing the turndown at the smallest sizes of most foundered crust and lake csds may be the result of coarsening making this process active both before and after eruption our csd modelling does not support significant crystal settling and overall convection in the lava lake although small advective currents are known to have occurred the olivine vertical stratification cannot be an original feature which is consistent with supposed strong stirring of the lake magma due to intense activity over the 17 eruptive phases it is also possible that independent basal feeding of the lake during the eruption may be needed to explain fully features of the chemical and mineralogical stratification

thermal radiance observations of an active lava flow during the june 1984 eruption of mount etna the thermal budget of an active lava flow observed on 20 june 1984 from the southeast crater of mount etna sicily italy was analyzed from data taken by the landsat thematic mapper the thematic mapper images constitute one of the few satellite data sets of sufficient spatial and spectral resolution to allow calibrated measurements on the distribution and intensity of thermal radiation from active lava flows using radiance data from two reflective infrared channels we can estimate the temperature and areas of the hottest parts of the active flow which correspond to hot 500 c fractures or zones at the flow surface using this technique we estimate that only 10 20 of the total radiated thermal power output is emitted by hot zones or fractures which constitute less than 1 of the observed surface area generally it seems that only where hot fractures or zones constitute greater than about 1 of the surface area of the flow will losses from such features significantly reduce internal flow temperatures using our radiance observations as boundary conditions for a multicomponent thermal model of flow interior temperature we infer that for the parts of this flow subject to analysis the boundary layer and flow thickness effects dominate over radiant zones in controlling the depression of core temperature

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

sediment yield determination using uranium series radionuclides the case of the wash and fenland drainage basin eastern england abstract water and sediment samples were collected from the fenland drainage basin to assess the fluvial contribution to the sediment budget of the wash on the east coast of england using the uranium series disequilibrium found in the products of the weathering system river sediment and water the ratio of material carried in solid form to that dissolved u s u w was assessed and the total flux of weathered material sediment yield was quantified the results show that the u s u w ratio is controlled to a degree by catchment geology and hydrology and that there is a marginal seasonal increase from between 3 28 3 95 and 4 60 0 44 summer mean and weighted mean to between 5 35 3 05 and 6 07 0 63 winter mean and weighted mean the best estimate of annual sediment flux from the fenland to the wash is between 2800 and 17 700 tonnes yr 1 equivalent to a rate of 0 22 1 42 tonnes km 2 yr 1 this is lower than previous estimates for the region but reinforces the argument that sediment reworking within the wash and erosion of the adjacent coasts and sea beds are important sources of sediment for the intertidal flats and salt marshes

volcano monitoring using short wavelength infrared data from satellites data from remote sensing satellites operating in the short wavelength infrared can be used to measure temperatures of about 150 c and above the gain settings of the landsat thematic mapper tm sensors are such that to record pixel integrated temperatures from 150 c to over 1000 c requires the use of several spectral bands if the radiant source occupies less than a whole pixel as is the case for fumaroles or a crusted lava surface with incandescent cracks then the pixel integrated temperature is less than the actual surface temperature of the hot areas and appears to be different at each wavelength by determining pixel integrated temperature in two spectral bands we can estimate both the temperature and size of hot areas which occupy less than a complete pixel in some cases our observations provide the only available data on the state of activity of a particular volcano in others they support and refine field observations our landsat tm data reveal otherwise unobserved precursor and subsequent activity related to the september 1986 eruption of lascar volcano chile and supplement other data on the march 1986 eruption of augustine volcano alaska they also indicate the continued presence of lava lakes at erta ale ethiopia in the absence of any ground based observations and document minor eruptive activity at mount erebus antarctica landsat multispectral scanner data have been used to measure the variation in temperature along a lava flow on sierra negra galapagos islands which occurred in 1979

diapirism on triton a record of crustal layering and instability cantaloupe terrain on neptune s large icy satellite triton comprises an organized cellular pattern of noncircular dimples that structurally and geologically most closely resemble salt diapirs exposed on earth the mean separation of these cells is 47 km modeling of the cells as compositionally driven diapirs suggests that cantaloupe terrain forms by gravity driven overturn within an ice crust about 20 km thick with a maximum viscosity of 10 exp 22 pa s these diapirs probably formed as a result of a density inversion in a layered crust composed partly of ice phases other than water ice

morphological features and processes in the central algarve rocky coast south portugal morphological features along the algarve rocky coast south portugal are identified and described with an emphasis on shore platforms and notches the contributions of processes such as wave attack chemical weathering and bioerosion to sculpting the shore platforms are discussed the preferential localization of shore platforms on sites exposed to waves and the lack of significant chemical weathering point to wave erosion as the first order factor in platform formation whilst bioerosion bioprotection lithology and geological structure determine platform morphological variations in addition platforms above the present intertidal zone appear to have a polygenetic evolution being inherited from former sea level highstands and currently undergoing chemical weathering the occurrence of notch features is independent of the degree of exposure to waves but they mostly occur where the substratum is sand hydrostatic pressure appears to be an important factor in the formation of marine caves in the more sheltered sites

the yield strength of subliquidus basalts experimental results yield strength is an important property of particle fluid suspensions in basaltic lavas that crystallize during flow emplacement the onset of yield strength may result in threshold transitions in flow behavior and flow surface morphology however yield strength crystallinity relations are poorly known particularly in geologic suspensions where difficulties of experimental and field measurements have limited data acquisition in the subliquidus temperature range here we describe two complementary experimental approaches designed to examine the effect of particle shape on the low shear yield strength of subliquidus basalts the first involves melting cubes of holocrystalline basalt samples with different initial textures to determine the temperature crystallinity at which these samples lose their cubic form these experiments provide information on the minimum crystal volume fractions 0 20 0 35 required to maintain the structual integrity of the cube the second set of experiments uses suspensions of corn syrup and neutrally buoyant particles to isolate the effect of particle shape on yield strength development from these experiments we conclude that the shape is important in determining the volume fraction range over which suspensions exhibit a finite yield strength as anisotropic particles may orient during flow the effect of particle shape will be controlled by the orientation distribution of the constituent particles we find that the so called excluded volume can be used to relate results of experiments on anisotropic particles to those of suspensions of spherical particles recent measurements of yield strength onset in basaltic melts at crystal volume fractions near 0 25 are consistent with our observations that crystal frameworks develop at low to moderate crystal volume fractions when crystals are anisotropic e g plagioclase we further suggest that conditions leading to yield strength onset at low crystallinities include rapid cooling increased crystal anisotropy heterogeneous nucleation which promotes extensive crystal clustering and large cluster anisotropy and static conditions random crystal orientations

the pleistocene faro quarteira formation of the algarve region southern portugal abstract the quartzite dominated faro quarteira formation covers a large proportion of the coastal lowlands of the algarve southern portugal the formation has been the subject of considerable controversy in the literature and ages ranging from the late miocene to the late pleistocene have been proposed while its mode of origin has been variously ascribed to fluvial aeolian and marine processes in this paper the geomorphology of the formation is described and this information together with that gleaned from the study of sections has not only allowed a model of emplacement to be proposed but has also cast light on its likely age of deposition we conclude that the faro quarteira formation was deposited by a combination of fluvial and debris flow activity and that it represents a glacis or mountain foot accumulation eroded from the interior of the algarve sediment sources include soils weathered bedrock and possible deposits from reworked former raised shorelines a contribution of aeolian sediment in the later stages of development is also probable by means of a combination of field mapping archaeological evidence and relationships with other dated quaternary formations a late pleistocene date seems most likely with sedimentation ending between 35 000 and 40 000 bp

observations and temperatures of io s pele patera from cassini and galileo spacecraft images abstract pele has been the most intense high temperature hotspot on io to be continuously active during the galileo monitoring from 1996 2001 a suite of characteristics suggests that pele is an active lava lake inside a volcanic depression in 2000 2001 pele was observed by two spacecraft cassini and galileo the cassini observations revealed that pele is variable in activity over timescales of minutes typical of active lava lakes in hawaii and ethiopia these observations also revealed that the short wavelength thermal emission from pele decreases with rotation of io by a factor significantly greater than the cosine of the emission angle and that the color temperature becomes more variable and hotter at high emission angles this behavior suggests that a significant portion of the visible thermal emission from pele comes from lava fountains within a topographically confined lava body high spatial resolution nightside images from a galileo flyby in october 2001 revealed a large relatively cool

emplacement and inflation of pahoehoe sheet flows observations and measurements of active lava flows on kilauea volcano hawaii inflated pahoehoe sheet flows have a distinctive horizontal upper surface which can be several hundred meters across and are bounded by steep monoclinal uplifts the inflated sheet flows we studied ranged from 1 to 5 m in thickness but initially propagated as thin sheets of fluid pahoehoe lava generally 20 30 cm thick individual lobes originated at outbreaks from the inflated front of a prior sheet flow lobe and initially moved rapidly away from their source velocities slowed greatly within hours due to radial spreading and to depletion of lava stored within the source flow as the outward flow velocity decreases cooling promotes rapid crustal growth at first the crust behaves plastically as pahoehoe toes form after the crust attains a thickness of 2 5 cm it behaves more rigidly and develops enough strength to retain incoming lava thus increasing the hydrostatic head at the flow front the increased hydrostatic pressure is distributed evenly through the liquid lava core of the flow resulting in uniform uplift of the entire sheet flow lobe initial uplift rates are rapid flows thicken to 1 m in 1 2 hours but rates decline sharply as crustal thickness increases and as outbreaks occur from the margins of the inflating lobe one flow reached a final thickness of nearly 4 m after 350 hr inflation data define power law curves whereas crustal cooling follows square root of time relationships the combination of data can be used to construct simple models of inflated sheet flows as the flow advances preferred pathways develop in the older portions of the liquid cored flow these pathways can evolve into lavatube systems within a few weeks formation of lava tubes results in highly efficient delivery of lava at velocities of several kilometers per hour to a flow front that may be moving 1 2 orders of magnitude slower if advance of the sheet flow is terminated the tube remains filled with lava that crystallizes in situ rather than draining to form the cave like lava tubes commonly associated with pahoehoe flows inflated sheet flows from kilauea and mauna loa are morphologically similar to some thick icelandic and submarine sheet flows suggesting a similar mechanism of emplacement the planar sheet like geometry of flood basalt flows may also result from inflation of sequentially emplaced flow lobes rather than nearly instantaneous emplacement as literal floods of lava

cyclic spattering seismic tremor and surface fluctuation within a perched lava channel kīlauea volcano in late 2007 a perched lava channel built up to 45 m above the preexisting surface developed during the ongoing eruption near pu u cone on k lauea volcano s east rift zone the lava channel was segmented into four pools extending over a total of 1 4 km from late october to mid december a cyclic behavior consisting of steady lava level rise terminated by vigorous spattering and an abrupt drop in lava level was commonly observed in pool 1 we use geologic observations video time lapse camera images and seismicity to characterize and understand this cyclic behavior spattering episodes occurred at intervals of 40 100 min during peak activity and involved small 5 10 m high fountains limited to the margins of the pool most spattering episodes had fountains which migrated downchannel each spattering episode was associated with a rapid lava level drop of about 1 m which was concurrent with a conspicuous cigar shaped tremor burst with peak frequencies of 4 5 hz we interpret this cyclic behavior to be gas pistoning and this is the first documented instance of gas pistoning in lava well away from the deeper conduit our observations and data indicate that the gas pistoning was driven by gas accumulation beneath the visco elastic component of the surface crust contrary to other studies which attribute similar behavior to the periodic rise of gas slugs the gas piston events typically had a gas mass of about 2 500 kg similar to the explosions at stromboli with gas accumulation and release rates of about 1 1 and 5 7 kg s 1 respectively the time averaged gas output rate of the gas pistoning events accounted for about 1 2 of the total gas output rate of the east rift zone eruption

rock coast geomorphology recent advances and future research directions there have been considerable advances in rock coast research in the past decade as measured in terms of the number of active researchers and in the number of research papers being produced this review although not exhaustive highlights many of the improvements that have been made in our ability to identify and measure the processes shaping rock coasts at a range of spatial and temporal scales we review how researchers are experimenting with new techniques grappling with quantifying the effects of multiple processes on resultant landforms and exploring how well rock coast systems relate to wider geomorphological and earth science debates recent research including those in this special issue aptly demonstrate the scientific benefits that can be accrued by studying rock coasts at a variety of spatial and temporal scales by considering the effect of the wide range of processes that operate on them and by the application of new measurement techniques and approaches despite these advances there is ample scope for future research which could profit from increasing collaboration with other coastal geomorphologists and allied earth science disciplines in order to identify and quantify linkages between rock coasts and other coastal systems it is also important that new research considers how rock coasts will respond to extreme events and to risks associated with changing climate and to how rock coast geomorphology might contribute beyond coastal science to wider debates in theoretical geomorphology

lava rise plateaus and inflation pits in the mccartys lava flow field new mexico an analog for pāhoehoe like lava flows on planetary surfaces

thermal signature eruption style and eruption evolution at pele and pillan on io the galileo spacecraft has been periodically monitoring volcanic activity on io since june 1996 making it possible to chart the evolution of individual eruptions we present results of coanalysis of near infrared mapping spectrometer nims and solid state imaging ssi data of eruptions at pele and pillan especially from a particularly illuminating data set consisting of mutually constraining near simultaneous nims and ssi observations obtained during orbit c9 in june 1997 the observed thermal signature from each hot spot and the way in which the thermal signature changes with time tightly constrains the possible styles of eruption pele and pillan have very different eruption styles from september 1996 through may 1999 pele demonstrates an almost constant total thermal output with thermal emission spectra indicative of a long lived active lava lake the nims pillan data exhibit the thermal signature of a pillanian eruption style a large vigorous eruption with associated open channel or sheet flows producing an extensive flow field by orbit c10 in september 1997 the high mass eruption rate high liquidus temperature at least 1870 k eruption at pillan is the best candidate so far for an active ultramafic magnesium rich komatiitic flow on io a style of eruption never before witnessed the thermal output per unit area from pillan is however consistent with the emplacement of large open channel flows magma temperature at pele is 1600 k if the magma temperature is 1600 k it suggests a komatiitic basalt composition the power output from pele is indicative of a magma volumetric eruption rate of 250 to 340 m3 s 1 although the pele lava lake is considerably larger than its terrestrial counterparts the power and mass fluxes per unit area are similar to active terrestrial lava lakes

investigating the volcanic versus aqueous origin of the surficial deposits in eastern elysium planitia mars abstract the elysium volcanic province consists of numerous overlapping flow units and may include the youngest lava flows on mars however it is possible that these volcanic units have been modified or overprinted by aqueous processes understanding the timing of the igneous and aqueous events in this region is therefore essential for constraining the geological and environmental history of mars during the amazonian period we investigate the geologic evolution of eastern elysium planitia to determine the relationship between major units with the support of a geological map and chronological constraints from crater size frequency distributions we also evaluate the hypothesized origin of these units via volcanic fluvial and or fluvioglacial processes using a detailed facies mapping approach the study area includes the eastern cerberus fossae rahway valles and marte vallis the surficial deposits in rahway valles were formerly interpreted to be modified by fluvial and fluvioglacial processes however our facies map reveals that the surface of eastern elysium planitia includes nineteen morphologically distinct regions i e facies which are interpreted to be the products of flood lava volcanism including a p hoehoe and transitional lava flow types in contrast to previous studies which determined that rahway valles and marte vallis consist of two distinct geologic units with middle to late amazonian ages the results of this work show that the region was resurfaced by at least two volcanic flows with much younger ages of 20 0 ma and 8 8 ma furthermore by coupling results of our geologic and facies mapping with chronological constraints as well as subsurface information provided by shallow radar reflectors we show that there is an erosional unconformity located between the two youngest lava flow units in marte vallis we interpret that this unconformity was generated by a catastrophic aqueous flooding event that occurred only 8 8 20 0 ma ago this implies alternating episodes of volcanism and aqueous flooding that have continued into the geologically recent past on mars and may again occur within elysium planitia

volcanic eruptions prediction hazard assessment remote sensing and societal implications in volcanology the period 1991 1994 was very busy with many active volcanoes keeping pace with the higher than average frequency of eruptions about 60 70 per year recorded during the late 1970 s to the late 1980 s simkin 1993 some large and violent eruptions occurred in well populated areas but these passed without the higher death tolls caused by eruptions in the previous decade a reflection perhaps of increased volcanic hazard awareness improved prediction and monitoring and better communication between volcanologists and public officials peterson and tilling 1993 the loss of human life was limited to a little over 1000 with perhaps 750 of these attributable to the mount pinatubo eruption on luzon in the philippines many were killed by post eruption phenomena such as mudflows and by disease in the displaced populations this large eruption which had a world wide atmospheric impact dominates the picture of volcanism in the early 1990 s however significant eruptions also occurred at hudson unzen spurr redoubt hekla mayon galeras rabaul kliuchevskoi etna the most voluminous lava outpourings this century and many other volcanoes here we assess the current state of volcano monitoring and hazard awareness against a backdrop of the eruptions of the past four years and take a look at future developments stressing new techniques in the field of remote sensing

automated monitoring of high temperature volcanic features from high spatial to very high temporal resolution developments in spaceborne earth observation eo sensor technology over the last decade combined with well tested physical models and multispectral data processing techniques developed from the early 1980s have paved the way to the global monitoring of volcanoes by sensors of metric decametric kilometric and multi kilometric spatial resolution such variable geometries provide for revisit intervals ranging from about monthly at high spatial resolution in low earth orbit to less than 5 min at low spatial resolution from geostationary platforms there are currently about 20 spacecrafts available for carrying out 24 7 quantitative observations of volcanic unrest at all resolutions and as close as possible to real time we show some successful examples of synergetic eo on volcanoes on three continents from 10 different payloads automatically processed with three end to end unsupervised procedures on eight major eruptions and a lava lake between 2006 and 2014

sources of alluvium in a coastal plain stream based on radionuclide signatures from the 238u and 232th decay series ratios 226 ra 232 th 226 ra 230 th and 230 th 232 th channel alluvium indicates a transition from interfluve surface to subsoil sources during flood subsoil 34 to 91 over about 8 km and bank full stages subsoil 9 to 74 over about 12 km with distance downstream these results indicate strong coupling between hillslope and channel processes reflecting land use change from forested to agricultural concentrated in lower loco bayou this methodology shows that sediment sources can be differentiated based upon landscape placement where lithologic contrast is absent the geochemistry long halflives and fractionation of 238 u and 232 th decay series radionuclides during pedogenic and fluvial processes in humid climates suggest that these methods are applicable in a wide variety of fluvial systems index terms 1040 geochemistry isotopic composition chemistry 1803 hydrology anthropogenic effects 1815 hydrology erosion and sedimentation 1824 hydrology geomorphology 1625 keywords natural radionuclides fingerprinting alluvium source apportioning

exhumed conduit records magma ascent and drain back during a strombolian eruption at tongariro volcano new zealand field evidence from a basaltic andesite dyke preserved in the eroded wall of a scoria cone at red crater tongariro volcano new zealand records a history of up conduit magma flow during a strombolian eruption subsequent drain back and final cessation of flow the dyke intrudes pre strombolian andesite lavas and the overlying proximal basaltic andesite scoria deposits associated with contemporaneous lavas which are in turn overlain by laminated lapilli tuff and large blocks textural and kinematic evidence of ductile shear recorded in basaltic andesite at the dyke margins records magma deformation imposed by bypassing movement of magma up the centre of the conduit during the eruption whereas the basaltic andesite occupying the central part of the lowermost exposures of the dyke preserves ductile flow folds with the opposite down flow shear sense the evidence indicates that the downward magma flow followed the eruption and this draining left the central part of the dyke empty unfilled at uppermost levels we discuss the kinematic constraints in the context of the criteria for up flow of mafic magma and present the factors most likely to result in a final drain back event with reference to experimental and numerical work we propose a draining model for the end of this eruption and that magmatic drain back may feature commonly during closing stages of strombolian eruptions at mafic volcanoes drain back which leaves large cavities in a volcanic edifice could result in hazardous structural instabilities

origins and implications of zigzag rift patterns on lava lakes abstract the distinctive rift patterns observed on newly formed lava lakes are very likely a product of interaction between heat transfer cooling of lava and deformation of the solid crust in response to applied stresses one common pattern consists of symmetric zigzag rifts separating spreading plates zigzags can be characterized by two measurable parameters an amplitude a and an angle between segments that make up the zigzags similar patterns are observed in analog wax experiments in which molten wax acts as cooling and solidifying lava we perform a series of these wax experiments to find the relationship between a and the cooling rate we develop a model to explain the observed relationships is determined by a balance of spreading and solidification speeds the amplitude a is limited by the thickness of the solid wax crust theoretical predictions agree well with experimental data this enables us to scale the model to basaltic lava lakes if zigzag rifts are observed on the surface of lava lakes and if physical properties of the lava crust can be measured or inferred by other means measurements of and a make it possible to calculate crust spreading velocity and crust thickness

morphology temperature and eruption dynamics at pele abstract the pele region of io has been the site of vigorous volcanic activity from the time of the first voyager i observations in 1979 up through the final galileo ones in 2001 there is high temperature thermal emission from a visibly dark area that is thought to be a rapidly overturning lava lake and is also the source of a large sulfur rich plume we present a new analysis of voyager i visible wavelength images and galileo solid state imager ssi and near infrared mapping spectrometer nims thermal emission observations which better define the morphology of the region and the intensity of the emission the observations show remarkable correlations between the locations of the emission and the features seen in the voyager images which provide insight into eruption mechanisms and constrain the longevity of the activity we also analyze an additional wavelength channel of nims data 1 87 m which paradoxically because of reduced sensitivity allows us to estimate temperatures at the peak locations of emission measurements of eruption temperatures on io are crucial because they provide our best clues to the composition of the magma high color temperatures indicative of ultramafic composition have been reported for the pillan hot spot and possibly for pele although recent work has called into question the requirement for magma temperatures above those expected for ordinary basalts our new analysis of the pele emission near the peak of the hot spot shows color temperatures near the upper end of the basalt range during the i27 and i32 encounters in order to analyze the observed color temperatures we also present an analytical model for the thermal emission from fire fountains which should prove generally useful for analyzing similar data this is a modification of the lava flow emission model presented in howell howell r r 1997 icarus 127 394 407 adapted to the fire fountain cooling curves first discussed in keszthelyi et al keszthelyi l jaeger w milazzo m radebaugh j davies a g mitchell k l 2007 icarus 192 491 502 when applied to the i32 observations we obtain a fire fountain mass eruption rate of 5 1 10 5 kg s 1 for the main vent area and 1 4 10 4 kg s 1 for each of two smaller vent regions to the west these fire fountain rates suggest a solution to the puzzling lack of extensive lava flows in the pele region much of the erupted lava may be ejected at high speed into the fire fountains and plumes creating dispersed pyroclastic deposits rather than flows we compare gas and silicate mass eruption rates and discuss briefly the dynamics of this ejection model and the observational evidence

observations of the effect of wind on the cooling of active lava flows 1 we present the first direct observations of the cooling of active lava flows by the wind we confirm that atmospheric convective cooling processes i e the wind dominate heat loss over the lifetime of a typical pahoehoe lava flow in fact the heat extracted by convection is greater than predicted especially at wind speeds less than 5 m s and surface temperatures less than 400 c we currently estimate that the atmospheric heat transfer coefficient is about 45 50 w m 2 k 1 for a 10 m s wind and a surface temperature 500 c further field experiments and theoretical studies should expand these results to a broader range of surface temperatures and wind speeds

evidence for a lava lake on mt michael volcano saunders island south sandwich islands from landsat sentinel 2 and aster satellite imagery abstract mt michael is an active stratovolcano on saunders island in the south sandwich islands a remote oceanic island arc in the southern atlantic ocean bordering the southern ocean the arc contains the only active volcanoes in the south georgia and south sandwich islands british overseas territory yet little is known of their activity despite lava lakes being extremely rare with only a few global examples previous analyses of satellite avhrr imagery of mt michael in the 1990s showed persistent thermal anomalies not associated with magma overflowing the crater this suggested the existence of a lava lake inside mt michael s crater however their study relied on 1 km resolution imagery and there have been no long term investigations to determine if this is a persistent feature in situ observations of mt michael are extremely difficult given the location we used landsat sentinel 2 and aster satellite data to monitor activity and detect thermal anomalies within the crater persistent volcanic plumes and eruptions were identified throughout the thirty year period studied on all 15 occasions that a suitable satellite image was available a thermal anomaly within the crater was detected in the high transmissivity shortwave infrared bands swir centred on 1 65 m and 2 2 m pixel integrated surface temperatures over the crater floor yield temperatures of 284 419 c comparable to lava lakes elsewhere unmixing these temperatures using the dual band method reveals a molten lava component at basaltic temperatures 989 1279 c among a cooler crust this is the first evidence for a lava lake within mt michael from data that can resolve the crater floor and the first evidence for magmatic temperatures as thermal anomalies were detected in all images showing the crater we suggest that the lava lake is a common and persistent feature

dynamics of mount nyiragongo lava lake inferred from thermal imaging and infrasound array abstract lava lakes provide a direct observation window into processes which usually remain hidden such as magma convection and outgassing dynamics we here report a coupled analysis of thermal infrared footage and infrasound array recordings at mount nyiragongo d r congo and derive a conceptual model of the lava lake s convective system and outgassing mechanism we suggest that surface flow results from a horizontal pressure gradient at the surface of the lake driving the crust from high pressure regions where hot upwelling magma impinges the surface to low pressure regions where cold downwelling magma pulls away from the surface the ascending current of this convection cell carries gas pockets which once at the surface are dragged across the lake into downwelling sinks such sinks are characterized by persistent chaotic bubble bursting spattering whose intensity and position are tracked from infrasound array analysis fluctuations of these are observed but have not been correlated with oscillations of the lava lake level nor with the variations of surface velocities both recorded from infrared footage we also report the activity of a new eruptive vent which opened early 2016 near an inner circular fracture of the crater s third terrace we show that the vent s activity was intermittent alternating between explosive strombolian activity and effusive activity the latter produced lava flows which spread on the crater s last terrace before cascading into the active lava lake although no significant change in the lake behavior was witnessed while the new eruptive vent was active increased attention should be addressed as this new activity could reflect over pressurization of the shallow magmatic system the variety of phenomena captured by this study complements and expands observations reported at other low viscosity lava lakes chiefly kilauea hawai i and erta ale ethiopia despite nyiragongo s more vigorous convective regime where multiple convective cells can operate simultaneously we suggest that the mechanisms controlling the surface motion and outgassing are similar at all three systems pointing to generic processes governing the dynamics of low viscosity lava lakes