hydrothermal element fluxes from copahue argentina a beehive volcano in turmoil copahue volcano erupted altered rock debris siliceous dust pyroclastic sulfur and rare juvenile fragments between 1992 and 1995 and magmatic eruptions occurred in july october 2000 prior to 2000 the copahue crater lake acid hot springs and rivers carried acid brines with compositions that reflected close to congruent rock dissolution the ratio between rock forming elements and chloride in the central zone of the volcano hydrothermal system has diminished over the past few years reflecting increased water rock ratios as a result of progressive rock dissolution magmatic activity in 2000 provided fresh rocks for the acid fluids resulting in higher ratios between rock forming elements and chloride in the fluids and enhanced mg fluxes the higher mg fluxes started several weeks prior to the eruption model data on the crater lake and river element flux determinations indicate that copahue volcano was hollowed out at a rate of about 20 000 25 000 m 3 yr but that void space was filled with about equal amounts of silica and liquid elemental sulfur the extensive rock dissolution has weakened the internal volcanic structure making flank collapse a volcanic hazard at copahue

birth growth and morphologic evolution of the laghetto cinder cone during the 2001 etna eruption we have undertaken detailed observations of the formation of the laghetto cinder cone a new cone that formed during a 2 week period of intense activity in piano del lago on the upper slopes of mount etna in summer 2001 we describe the events leading to the formation of a small graben the formation of pit craters on the base of the graben the onset of phreatomagmatic activity a transition to intense strombolian activity and a return to phreatomagmatic activity as the eruption came to an end we discuss the reasons for these transitions and describe the morphological development of the cone during these events arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim some of the failure planes we observed were first identified using a flir tm 695 thermal infrared camera this is the first time that infrared thermography has been used to detect instability of volcanic structures results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability

transition from mildly tholeiitic to calc alkaline suite the case of chichontepec volcanic centre el salvador central america abstract the chichontepec volcano is a plio pleistocene composite volcano that erupted lavas ranging from high alumina basalts to dacites it experienced a caldera forming paroxysmal eruption during the early pleistocene pre caldera lavas are mildly tholeiitic and they evolved mainly by low pressure crystal fractionation notwithstanding the fact that most mafic lavas low mgo high alumina basalts retain traces of polybaric evolution conversely post caldera lavas which are mainly pyroxene andesites are clearly calc alkaline having evolved by open system crystal fractionation sr nd isotopic data and trace elements characteristics indicate that the same mantle source was involved in the petrogenesis of these series modelling the afc process showed that it did not play any role in the petrogenesis of these rocks a crystal fractionation model is considered to be more relevant a slight variation in the fractionating assemblage could have caused the transition from an early mildly tholeiitic trend to a late calc alkaline one mineralogical evidence mass balance calculations and elemental chemistry support this hypothesis assuming that the greater amount of pyroxene on the liquidus is at the expense of plagioclase this would have prevented the trend in iron enrichment

diagenetic alteration of the structure and δ18o signature of palaeozoic fish and conodont apatite potential use for corrected isotope signatures in palaeoenvironmental interpretation abstract the oxygen isotopic compositions of carboniferous conodonts and fish microfossils ichthyoliths from identical samples were analysed in tandem in order to test whether these phosphatic media can be reliably used for palaeoclimatic reconstruction the structure of conodonts and of most ichthyoliths analysed are somewhat analogous to the enamel and dentine bone tissue respectively of modern mammals therefore the diagenetic susceptibilities of the taxa analysed may provide important clues to other palaeoclimatic studies utilising a variety of biogenic apatite thermal maturation indices and scanning electron microscopy were used to characterise the preservation of biogenic apatite despite a high conodont colour alteration index cai of 5 5 conodont elements appear to have been only mildly affected by diagenetic alteration in contrast ichthyoliths were commonly recrystallised and exhibited diagenetic apatitic overgrowths containing amorphous pyrolytic carbon interpreted as indicating that at least some overgrowth material derived from the original biogenic apatite diagenetic alteration has resulted in ichthyolith 18 o values being systematically lower by on average 2 9 1 0 3 relative to conodont apatite conodont samples yielded regionally correlatable isotope values which can be interpreted in terms of more palaeoenvironmentally sensible palaeotemperatures relative to ichthyolith values densely crystalline enamel like conodont elements are interpreted as the more robust phosphatic medium to preserve original isotopic compositions the strong correlation r 0 8 of the 18 o values of the more structurally pristine conodont and commonly recrystallised ichthyolith apatite indicates that i despite diagenetic lowering of absolute isotope values original palaeoenvironmental records may be preserved and ii diagenetic overprinting may result in a stable offset and therefore be correctable locally

comparing oxygen isotope records of silurian calcite and phosphate δ18o compositions of brachiopods and conodonts oxygen isotope compositions of silurian calcitic brachiopod shells from gotland are compared with those of phosphatic inarticulate brachiopod shells and conodonts from identical stratigraphic horizons the 18ophosphate values of inarticulate brachiopod shells vary widely 13 0 to 17 5 v smow and are significantly lower than those of coeval conodont samples 17 5 to 19 5 v smow conodont samples from individual beds have homogenous 18ophosphate values with variations close to the analytical precision 0 2 together with a significant correlation of conodont 18ophosphate and articulate brachiopod shell 18ocarbonate values r 0 85 this observation suggests that primary marine oxygen isotope compositions are better preserved in conodont apatite than in inarticulate brachiopod shell apatite however with decreasing 18ocarbonate values the 18ophosphate values of conodonts are higher than expected for theoretical isotopic equilibrium with brachiopod calcite different habitats of conodonts and brachiopods cannot account for the observed offset in 18o because both organisms were thriving on a broad shallow marine carbonate platform whereas 18ophosphate values of silurian conodonts are close to 18ophosphate values of modern and mesozoic tropical biogenic apatites most silurian calcitic brachiopod shells from gotland are depleted in 18o when compared to modern or mesozoic brachiopods we therefore suggest that silurian conodonts from gotland record paleotemperature and 18o of silurian sea water more faithfully than coeval calcitic brachiopod shells

the late frasnian kellwasser horizons of the harz mountains germany two oxygen deficient periods resulting from different mechanisms in the harz mountains germany three late devonian sections aeketal huhnertal and kellwassertal were analyzed for major and trace element concentration the inorganic geochemical data were used to determine the environmental conditions associated with the deposition of the two late frasnian black kellwasser horizons in a submarine rise environment low ti al and zr al values and slight enrichment in nutrient and organic matter related trace elements e g ba cu and ni suggest that the kellwasser horizons were deposited during two periods of minimum detrital input but relatively elevated primary production enrichments in u v and mo in both black kellwasser horizons and values of redox indices including u th v cr and ni co indicate oxygen restricted conditions prevailed during the late frasnian times under oxygen depleted conditions reductive diagenesis caused precipitation of iron sulphides such as pyrite that are observed with sem however variations in major and trace element concentrations are not similar in the two kellwasser horizons particularly regarding redox markers the lower kellwasser horizon seems to be more o2 depleted than the upper kellwasser horizon in some german sections on the basis of these results we propose that the two kellwasser horizons are not caused by identical conditions the lower kellwasser horizon results from increased primary productivity enhanced by land derived nutrient loading and which triggered the anoxic conditions recorded in drowned platform setting in contrast the upper kellwasser horizon results from the onset of oxygen impoverished bottom water in the deepest part of the ocean due to episodic water stratification during maximum frasnian flooding oxygen depleted water may have impinged shallower environment during the linguiformis transgressive pulse nutrients would have been released from organic matter decay under reducing conditions and brought up to the photic zone during episodic water mixing

evidences of volcanic unrest on high temperature fumaroles by satellite thermal monitoring the case of santa ana volcano el salvador on october 1st 2005 santa ana volcano el salvador underwent a vei 3 phreatomagmatic eruption after approximately one century of rest casualties and damages to some of the local infrastructures and surrounding plantations were followed by the evacuation of the nearby communities the analysis of modis moderate resolution imaging spectroradiometer infrared data reveals that the main explosion was preceded by a one year long thermal unrest associated to the development of a fumaroles field located at the western rim of the summit crater lake by combining space based thermal flux and ground based measurements seismicity sulfur emissions and lake temperatures we suggest that the activity observed at santa ana between 2004 and 2005 was driven by the gradual intrusion of an undegassed magma body at a very shallow depth magma injection induced thermal anomalies associated with sustained degassing from the fumaroles field and promoted the interaction between the magmatic hydrothermal system and the overlying water table this process culminated into the vei 3 phreatomagmatic eruption of october 2005 that strongly modified the shallow structure of the crater area the subsequent three years long activity resulted from self sealing of the fracture system and by the opening of a new fracture network directly connecting the deeper hydrothermal system with the crater lake our results show that satellite based thermal data allow us to detect the expansion of the high temperature fumarolic field this may precede an explosive eruption and or a lava dome extrusion in particular we show that thermal records can be analyzed with other geochemical i e so2 emissions and geophysical seismicity data to track a shallow magmatic intrusion interacting with the surrounding hydrothermal system this provides a remarkable support for volcano monitoring and eruption forecasting particularly in remote areas where permanent ground data acquisition is hazardous expensive and difficult

first study of the heat and gas budget for sirung volcano indonesia with at least four eruptions over the last 20 years sirung is currently one of the more active volcanoes in indonesia however due to its remoteness very little is known about the volcano and its hyperacid crater lake we report here on the first measurements of gas and heat emissions from the volcano notable is the substantial heat loss from the crater lake surface amounting to 220 mw in addition 17 gg of so2 representing 0 8 of indonesian volcanic so2 contribution into the atmosphere 11 gg of h2s 17 gg of co2 and 550 gg of h2o are discharged into the atmosphere from the volcano annually the volatiles degassed from sirung magmas are subjected to hydrothermal fluid rock interactions and sulfide depositions initiated by the disproportionation of so2 these processes lead to distinct gas compositions and changing lake water chemistry in the sub craters and the main crater lake however the occurrence of so2 rich fluids and strong gas flux appear to highlight a rapid fluid transfer to surface avoiding re equilibration with lower temperature rocks fluids in the conduits

anomalous emissions of so2 during the recent eruption of santa ana volcano el salvador central america santa ana volcano in western el salvador central america had a phreatic eruption at 8 05 am local time on october 1 2005 101 years after its last eruption however during the last one hundred years this volcano has presented periods of quiet degassing with fumarolic activity and an acidic lake within its crater this paper presents results of frequent measurements of so2 degassing using the minidoas differential optical absorption spectroscopy system and a comparison with the volcanic seismicity prior to the eruption during and after the eruption vehicle measurements of so2 flux were taken every hour during the first nine days of the eruption and daily after that the period of time reported here is from august to december 2005 three periods of degassing are distinguished pre eruptive eruptive and post eruptive periods the intense activity at santa ana volcano started in july 2005 during the pre eruptive period up to 4306 and 5154 ton day of so2 flux were recorded on october 24 and september 9 2005 respectively these values were of the same order of magnitude as the recorded values just after the october 1st eruption 2925 ton day at 10 01 am hourly measurements of so2 flux taken during the first nine days after the main eruptive event indicate that explosions are preceded by an increase in so2 flux and that this parameter reaches a peak after the explosion took place this behavior suggests that increasing accumulation of exsolved magmatic gases occurs within the magmatic chamber before the explosions increasing the pressure until the point of explosion a correlation between so2 fluxes and rsam real time seismic amplitude measurements is observed during the complete sampling period periodic fluctuations in the so2 and rsam values during the entire study period are observed one possible mechanism explaining these fluctuations it that convective circulation within the magmatic chamber can bring fresh magma periodically to shallow levels allowing increasing degasification and then decreasing degasification as the batch of magma lowers its gas content becomes denser and sinks to give space to a new magma pulse these results illustrate that the measurements of so2 flux can provide important warning signals for incoming explosive activity in active volcanoes

thermal evolution of the crater lake of copahue volcano with aster during the last quiescence period between 2000 and 2012 eruptions abstract active crater lakes are the surface expression of volcanic activity at the top of complex magmatic hydrothermal systems the volcanic and hydrothermal system copahue is one of the most important active systems in argentina it lies at the border of argentina and chile and is very important since the copahue and caviahue towns are very close and constitute important touristic resources including a ski center the aim of this work is to improve the temperature register of the volcano and contribute towards a better understanding of the thermal behavior of the system during the quiescence period between the 2000 and 2012 eruptions the surface temperature of the crater lake was estimated by using the normalized emissivity method nem on 70 images acquired by the advanced spaceborne thermal emission and reflection radiometer aster and we combined them with field measurements in order to capture the fundamental variations of the system the analysis allowed the identification of two different thermal periods i january 2001 august 2003 and ii december 2004 november 2011 characterized by temperature ranges of 43 50 c and 30 45 c respectively beyond these ranges temperature anomalies or moments of high temperature variability occurred which corresponded to surface expressions of volcanic activity in august 2004 the lake froze almost completely whereas in march 2012 peak temperatures were recorded however a significant drop in temperature prior to the eruption of december 22 2012 was observed which might constitute a characteristic feature of the system furthermore the crater lake of copahue volcano is classified as a lake of high activity the observations and interpretations presented constitute a useful baseline and a significant contribution towards a better understanding of the functioning of the volcano the mitigation of volcanic hazards and the identification of volcanic unrest

crater lake temperature changes of the 2005 eruption of santa ana volcano el salvador central america a sudden eruption at santa ana occurred on 1 october 2005 producing an ash and gas plume to a height in excess of 10 km above the volcano several days before thermal infrared images of the crater provided precursory signals of the eruption a significant increase in the extent and intensity of the fumarolic field inside the crater rim and of the surface temperature of the crater s lake was observed changes in energy input was also estimated to explain the increase in lake temperature based on energy mass balance calculations

record of climate driven morphological changes in 376 ma devonian fossils the lower and upper kellwasser horizons represent two anoxic events that mark the mass extinction at the frasnian famennian f f boundary among other groups conodont animals were severely affected but the genus palmatolepis survived with a complete turnover at the f f boundary here the fine morphological variations of the genus palmatolepis and the sea surface temperature evolution are quantified in two f f boundary sections using morphometrics and oxygen isotopic composition of apatite respectively in accordance with other f f sections the isotope records show two positive excursions of 1 during the lower and upper kellwasser anoxic events the conodont shape and the oxygen isotopic composition of the genus palmatolepis are significantly correlated within the frasnian and famennian stages suggesting a strong environmental influence on the morphology of the feeding apparatus of the conodont animal we propose that the morphological differences are linked to changes in the trophic position of palmatolepis enhanced organic carbon burial which is supported by global positive carbon isotope excursions in inorganic and organic carbon during both the lower and upper kellwasser events altered the primary biomass production and thus the subsequent nutrient supply to higher trophic levels while the carbon and oxygen isotopic shifts are of similar amplitude during lower and upper kellwasser events the variation of the shape of palmatolepis during the upper kellwasser i e the f f boundary is more pronounced than during the lower kellwasser

dynamic fluid recycling at laguna caliente poas costa rica before and during the 2006 ongoing phreatic eruption cycle 2005 10

self potential modeling from primary flows this paper discusses a new method for the investigation of self potentials sp based on induced current sources the induced current sources are due to divergences of the convection current which is driven in turn by a primary flow either heat or fluid as a result of using this approach there is a shift in emphasis toward the vector flow field and its interaction with current cross coupling structure when compared with the total potential approach of nourbehecht 1963 which emphasized the primary flow potential and the voltage cross coupling this shift in emphasis is advantageous because it is analogous to the actual physical processes for example fluid flow in the ground gives rise to drag convection currents and the interaction of the convection currents with the electrical structure gives rise to the electrical potentials sp this simple physical picture should aid in developing a better intuitive understanding of the generation of sp effects the convective current approach is easily ada

late devonian carbon isotope stratigraphy and sea level fluctuations canning basin western australia the upper devonian reef complexes of the canning basin contain some of the world s best exposed continuous stratigraphic sections through the frasnian famennian boundary the facies distribution and composition of these reef complexes record interactions among sea level changes sediment supply ocean chemistry and paleoecology changes in relative sea level produced spatial shifts in reef platform development and regional changes in sediment supply that can be correlated across facies boundaries using a combination of sequence stratigraphy biostratigraphy and carbon isotope stratigraphy during the lowstand interval below the frasnian famennian boundary the reef margin advanced down the reef slope in shallow water environments and siliciclastics locally dominated in the marginal slope environment compilation of a broad late frasnian to early famennian sequence stratigraphic framework for the canning basin demonstrates that transgressive intervals correlate to positive carbon isotopic excursions within the basin these isotopic shifts also can be correlated to time equivalent positive carbon isotopic excursions reported from transgressive intervals in europe thus the late frasnian transgressions in the canning basin were primarily eustatic rather than tectonic in origin and positive carbon isotopic signatures of the kellwasser horizons are globally correlative c 2002 elsevier science b v all rights reserved

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

water and dissolved gas geochemistry at coatepeque ilopango and chanmico volcanic lakes el salvador central america abstract coatepeque on the e slope of santa ana volcano ilopango inside ilopango caldera and chanmico associated with san salvador volcano are volcanic lakes in el salvador showing a thermocline at a relatively shallow depth from 30 to 40 m from 20 to 40 m and from 5 to 15 m depth respectively and anoxic conditions below 33 24 and 4 m depth respectively the na cl composition of the coatepeque and ilopango lakes displaying tds values up to 1226 and 1216 mg l respectively is likely due to hydrothermal fluids that feed these two lakes as also confirmed by cl br molar ratios 650 high as b li and si contents and cl so42 ratio 1 the mg2 hco3 water composition of lake chanmico whose tds values were between 566 and 856 mg l suggests water rock interaction processes with mafic ultramafic rocks variably affected by serpentinization processes which produced high mg2 si and b concentrations waters at depth were characterized by the presence of co2 from an extra lacustrine source as suggested by 13c co2 values significantly less negative than those typically related to biogenic processes albeit this gas was found in smaller quantities when compared to those recorded in other meromictic lakes hosted in quiescent volcanic systems e g lake kivu in drc monticchio albano and averno lakes in italy hule and rio cuarto lakes in costa rica lake pavin in france the occurrence of ch4 whose concentrations in lake chanmico were up to two orders of magnitude higher than those recorded in coatepeque and ilopango lakes suggests bacterial methanogenesis

a scale interaction study on east asian cyclogenesis using a general circulation model coupled with an interactively nested regional model this study newly developed the interactively nested climate model incl using a general circulation model gcm interactively nested with a regional atmospheric model ram one interactive experiment with finer ram topography and another with coarser topography as well as offline versions of each experiment were performed to investigate the effects of subsynoptic scale eddies and subsynoptic scale mountains in northeast asia on the larger scale climate using the gcm with t42 atmosphere and the ram with 40 km mesh size in the incl system the subsynoptic scale eddy effect restrictively increased synoptic scale eddy activity within the ram domain in contrast subsynoptic scale mountains had the effect of robust anticyclonic circulation around the sea of japan and effectively forced larger scale circulation the effect was positively fed back to the mean field and amplified the anticyclonic circulation accompanied by suppressed storm activity in northeast asia the results suggest that subsynoptic scale mountains affect not only subsynoptic scale eddies but also the global climate

volcano surveillance using infrared cameras abstract volcanic eruptions are commonly preceded accompanied and followed by variations of a number of detectable geophysical and geochemical manifestations many remote sensing techniques have been applied to tracking anomalies and eruptive precursors and monitoring ongoing volcanic eruptions offering obvious advantages over in situ techniques especially during hazardous activity whilst spaceborne instruments provide a distinct advantage for collecting data remotely in this regard they still cannot match the spatial detail or time resolution achievable using portable imagers on the ground or aircraft hand held infrared camera technology has advanced significantly over the last decade resulting in a proliferation of commercially available instruments such that volcano observatories are increasingly implementing them in monitoring efforts improved thermal surveillance of active volcanoes has not only enhanced hazard assessment but it has contributed substantially to understanding a variety of volcanic processes drawing on over a decade of operational volcano surveillance in italy we provide here a critical review of the application of infrared thermal cameras to volcano monitoring following a summary of key physical principles instrument capabilities and the practicalities and methods of data collection we discuss the types of information that can be retrieved from thermal imagery and what they have contributed to hazard assessment and risk management and to physical volcanology with continued developments in thermal imager technology and lower instrument costs there will be increasing opportunity to gather valuable observations of volcanoes it is thus timely to review the state of the art and we hope thereby to stimulate further research and innovation in this area

microbial mounds prior to the frasnian famennian mass extinctions hantang guilin south china late frasnian mounds of the yunghsien formation guilin south china developed as part of the guilin platform mostly in reef flat and platform margin settings microbial mounds in platform margin settings at hantang about 10 km west of guilin contain frasnian biota such as stachyodes and kuangxiastraea and thus occur below the frasnian famennian mass extinction boundary platform margin facies were dominated by microbes algae and receptaculitids massive corals and stromatoporoids are not common and rarely show reef building functions as they did in givetian time the margin mounds are composed of brachiopod receptaculitid cementstone and a variety of boundstones that contain rothpletzella renalcis thrombolite and stromatolite other microbial communities include girvanella izhella ortonella and wetheredella solenoporoid algae are abundant locally zebra structures and neptunian dykes are well developed at some intervals pervasive early cementation played an important role in lithification of the microbial boundstones and rudstones frasnian reefs of many regions of the world were constructed by stromatoporoids and corals although a shift to calcimicrobe dominated frameworks occurred before the famennian however the exact ages of many frasnian margin outcrops are poorly constrained owing to difficulties dating shallow carbonate facies the hantang mounds represent a microbe dominated reef building community with rare skeletal reef builders consistent with major late devonian changes in reef composition diversity and guild structure occurring before the end of the frasnian a similar transition occurred in the canning basin of western australia but coeval successions in north america western europe and the northern urals are either less well known or represent different bathymetric settings the transition in reef building style below the frasnian famennian boundary is documented here in the two best exposed successions on two continents which may have been global set in the larger context of late devonian and mississippian microbial reef building the hantang mounds help to demonstrate that controls on microbial reef communities differed from those on larger skeletal reef biota calcimicrobes replaced stromatoporoids as major reef builders before the frasnian famennian extinction event and increasing stromatoporoid diversity towards the end of the famennian did not result in a resurgence of skeletal reef frameworks calcimicrobes dominated margin facies through the famennian but declined near the devonian carboniferous boundary stromatolite and thrombolite facies which occurred behind the mound margin at hantang rose to dominate mississippian shallow water reef frameworks with only a minor resurgence of the important frasnian calcimicrobe renalcis in the visean when well skeletonized organisms corals also became volumetrically significant frame builders again

thermal precursors in satellite images of the 1999 eruption of shishaldin volcano shishaldin volcano unimak island alaska began showing signs of thermal unrest in satellite images on 9 february 1999 a thermal anomaly and small steam plume were detected at the summit of the volcano in short wave thermal infrared avhrr advanced very high resolution radiometer satellite data this was followed by over 2 months of changes in the observed thermal character of the volcano initially the thermal anomaly was only visible when the satellite passed nearly directly over the volcano suggesting a hot source deep in the central crater obscured from more oblique satellite passes the zenith angle needed to see the anomaly increased with time presumably as the thermal source rose within the conduit based on this change an ascent rate of ca 14 m per day for the thermal source was estimated until it reached the summit on around 21 march it is thought that strombolian activity began around this time the precursory activity culminated in a sub plinian eruption on 19 april ejecting ash to over 45 000 ft 13 700 m the thermal energy output through the precursory period was calculated based on geometric constraints unique to shishaldin these calculations show fluctuations that can be tied to changes in the eruptive character inferred from seismic records and later geologic studies the remote location of this volcano made satellite images a necessary observation tool for this eruption to date this is the longest thermal precursory activity preceding a sub plinian eruption recorded by satellite images in the region this type of thermal monitoring of remote volcanoes is central in the efforts of the alaska volcano observatory to provide timely warnings of volcanic eruption and mitigate their associated hazards to air traffic and local residents

hydroacoustic noise precursors of the 1990 eruption of kelut volcano indonesia abstract the results of a hydroacoustic monitoring experiment in the kelut crater lake indonesia prior to its 1990 eruption are presented with the benefit of hindsight indeed the underwater noise levels in three widely separated frequency bands together with the lake water temperature was radio transmitted and almost continuously recorded from a period of quiescence of the volcano till the onset of its 10 february 1990 eruption which destroyed the monitoring buoy the comparative analysis of the noise variations in the three bands together with seismic and temperature data have shed light on the mechanisms underlying the pre eruptive activity the three acoustic levels had shown conspicuous yet distinctive changes prior to the eruption acoustic level in the low frequency 1 50 hz band which increased one year before the resumption of seismic activity and the lake warming up is interpreted as the result of boiling at depth the source of high acoustic level in the audiometric 500 5000 hz range is clearly the bubbling of volcanic gases occurring as a strong convective column in the middle of the lake from the variations of this audiometric level we have estimated that the degassing rate in the lake increased by a hundred fold during the pre eruptive period variations of ultrasonic 20 100 khz frequency acoustic level seem to be related with pressure and thermal changes within the hydrothermal system and its rock matrix beneath the lake in conclusion this experiment demonstrates the potential of hydroacoustic monitoring as an early warning system at crater lake volcanoes

conodont sr ca and δ18o record seawater changes at the frasnian famennian boundary abstract the oxygen isotopic composition 18 o p and strontium calcium sr ca p ratios have been measured in late devonian conodonts palmatolepis sp from contemporaneous sections at coumiac france and m rirt morocco the sequences encompass two anoxic horizons the lower kellwasser lkw and upper kellwasser ukw events with the top of the ukw coinciding with the mass extinction at the frasnian famennian boundary the genus palmatolepis survived the faunal crisis but exhibited plastic responses to the environmental changes which are recorded in the evolution of shape during the anoxic events the present study demonstrates that shape 18 o p and sr ca p values of conodonts are correlated in both localities excluding diagenesis as the driving process for the measured 18 o p and sr ca p values the conodonts 18 o p and sr ca p values are correlated in both localities and distributed into either a pre crisis and crisis group using the relationships between the 18 o p and sr ca p values we estimate that the variation of the seawater sr ca ratio during the frasnian famennian mass extinction was of about 20 its initial value this drastic decrease of the seawater sr ca ratio is discussed in the light of the reef demise that occurred during the faunal crisis

volcanology 2020 how will thermal remote sensing of volcanic surface activity evolve over the next decade abstract volcanological remote sensing spans numerous techniques wavelength regions data collection strategies targets and applications attempting to foresee and predict the growth vectors in this broad and rapidly developing field is therefore exceedingly difficult however we attempted to make such predictions at both the american geophysical union agu meeting session entitled volcanology 2010 how will the science and practice of volcanology change in the coming decade held in december 2000 and the follow up session 10 years later looking backward and forward volcanology in 2010 and 2020 in this summary paper we assess how well we did with our predictions for specific facets of volcano remote sensing in 2000 the advances made over the most recent decade and attempt a new look ahead to the next decade in completing this review we only consider the subset of the field focused on thermal infrared remote sensing of surface activity using ground based and space based technology and the subsequent research results this review keeps to the original scope of both agu presentations and therefore does not address the entire field of volcanological remote sensing which uses technologies in other wavelength regions e g ultraviolet radar etc or the study of volcanic processes other than the those associated with surface mostly effusive activity therefore we do not consider remote sensing of ash gas plumes for example in 2000 we had looked forward to a golden age in volcanological remote sensing with a variety of new orbital missions both planned and recently launched in addition exciting field based sensors such as hand held thermal cameras were also becoming available and being quickly adopted by volcanologists for both monitoring and research applications all of our predictions in 2000 came true but at a pace far quicker than we predicted relative to the 2000 2010 timeframe the coming decade will see far fewer new orbital instruments with direct applications to volcanology however ground based technologies and applications will continue to proliferate and unforeseen technology promises many exciting possibilities that will advance volcano thermal monitoring and science far beyond what we can currently envision

using crater lake chemistry to predict volcanic activity at poas volcano costa rica monitoring of crater lake chemistry during the recent decline and disappearance of the crater lake of poas volcano revealed that large variations in so4 cl f cl and mg cl ratios were caused by the enhanced release of hcl vapor from the lake surface due to increasing lake temperature and solution acidity variation in the concentration of polythionic acids h2sxo6 x 4 6 was the most reliable predictor of renewed phreatic eruptive activity at the volcano exhibiting sharp decreases three months prior to the initiation of phreatic eruptions in june 1987 polythionic acids may offer a direct indicator of changing subsurface magmatic activity whereas chloride based element ratios may be influenced by surface volatilization of hcl and subsequent recycling of acidic fluids in crater lake volcanoes

high spatio temporal resolution observations of crater lake temperatures at kawah ijen volcano east java indonesia the crater lake of kawah ijen volcano east java indonesia has displayed large and rapid changes in temperature at point locations during periods of unrest but measurement techniques employed to date have not resolved how the lake s thermal regime has evolved over both space and time we applied a novel approach for mapping and monitoring variations in crater lake apparent surface skin temperatures at high spatial 32 cm and temporal every 2 min resolution at kawah ijen on 18 september 2014 we used a ground based flir t650sc camera with digital and thermal infrared tir sensors from the crater rim to collect 1 a set of visible imagery around the crater during the daytime and 2 a time series of co located visible and tir imagery at one location from pre dawn to daytime we processed daytime visible imagery with the structure from motion photogrammetric method to create a digital elevation model onto which the time series of tir imagery was orthorectified and georeferenced lake apparent skin temperatures typically ranged from 21 to 33 c at two locations apparent skin temperatures were 4 and 7 c less than in situ lake temperature measurements at 1 5 and 5 m depth respectively these differences as well as the large spatio temporal variations observed in skin temperatures were likely largely associated with atmospheric effects such as the evaporative cooling of the lake surface and infrared absorption by water vapor and so2 calculations based on orthorectified tir imagery thus yielded underestimates of volcanic heat fluxes into the lake whereas volcanic heat fluxes estimated based on in situ temperature measurements 68 to 111 mw were likely more representative of kawah ijen in a quiescent state the ground based imaging technique should provide a valuable tool to continuously monitor crater lake temperatures and contribute insight into the spatio temporal evolution of these temperatures associated with volcanic activity

volcanic lake systematics i physical constraints volcanic lakes have a wide range of characteristics and we make an attempt to delineate the limiting physical conditions for several lake classes the ratio between heat input and heat dissipation capacity of a lake constrains the temperature for perfectly mixed steady state volcanic lakes poorly mixed lakes are also conditioned by this ratio but their temperature structure is also strongly influenced by the hydrodynamics resulting from different mechanisms of heat transfer the steady state temperatures of volcanic lakes are largely determined by the magnitude of the volcanic heat influx relative to the surface area of the lake small lakes have only a small capacity for heat dissipation and their temperature rises quickly with only small heat inputs large lakes are buffered against variations in heat input both the heat dissipation and meteoric water input into a lake are functions of lake surface area and therefore each lake water temperature demands a certain precipitation rate for mass conservation independent of lake size the results of energy mass balance modeling shows that under common atmospheric conditions most steady state volcanic lakes are unlikely to maintain a temperature in excess of 45 50 c validation of the volcanic lake model was performed using published data from yugama lake japan and the keli mutu lakes indonesia also the model was applied to 24 natural systems to provide a baseline assessment of energy fluxes under the model assumptions so future work on those systems can identify nuances in individual systems that deviate from the simple model conditions we recommend the model for use in assessing temperature variations and volcanic lake stability in settings with known physical and atmospheric conditions application of the energy mass balance calculations of model lakes provides a genetic classification scheme largely based on physical process parameters

carbon isotopic evidence for the associations of decreasing atmospheric co2level with the frasnian famennian mass extinction 1 a perturbation of the global carbon cycle has often been used for interpreting the frasnian famennian f f mass extinction however the changes of atmospheric co2 level pco2 during this interval are much debatable to illustrate the carbon cycle during f f transition paired inorganic 13ccarb and organic 13corg carbon isotope analyses were carried out on two late devonian carbonate sequences dongcun and yangdi from south china the larger amplitude shift of 13corg compared to 13ccarb and its resultant 13c 13c 13ccarb 13corg decrease indicate decreased atmospheric co2level around the f f boundary the onset ofpco2 level decrease predates that of marine regressions which coincide with the beginning of conodont extinctions suggesting that temperature decrease induced by decreased greenhouse effect of atmospheric co2might have contributed to the f f mass extinction