co2 emissions related to the yellowstone volcanic system 2 statistical sampling total degassing and transport mechanisms a stratified adaptive sampling plan was designed to estimate co2 degassing in yellowstone national park and was applied in the mud volcano thermal area the stratified component of the sampling design focused effort in thermal areas and the adaptive component in high flux regions yet neither sampling technique biased the estimate of total degassing both diffuse soil fluxes up to 30 000 g m 2d 1 and emission rates from thermal vents up to 1 7 108 mol yr 1 were measured in thermal areas soil fluxes observed in most nonthermal regions were similar to values reported for conifer forests 15 g m 2 d 1 however through adaptive sampling high flux vegetated sites were identified in mud volcano that likely would not have been found if sampling was focused in obvious thermal or altered regions a simple model applied to flux measurements suggests that 40 of the analyzed measurements were dominated by possible advective transport and 30 by diffusive transport isotopic signatures of soil co2 generally suggest a deep origin 13c 2 3 to 0 0 in thermal areas and biogenic origin 13c 20 5 in nonthermal low flux areas vent emissions accounted for 32 63 of the total degassing observed at mud volcano 2 4 to 4 0 109 mol yr 1 the largest source of error in the estimation of total degassing factor of 2 resulted because the population distribution of thermal feature emissions was indeterminate total co2 emissions at mud volcano are comparable to other hydrothermal regions worldwide suggesting that the yellowstone volcanic system is likely a large contributor to global volcanic metamoohic hydrothermal vmh emissions

nannoplankton successions in the northern red sea during the last glaciation 60 to 14 5 ka bp reactions to climate change abstract due to its restricted connection with the indian ocean the desert enclosed red sea is extremely sensitive to global sea level changes and thus ideally suited for paleoceanographic studies of what occurred during the last glaciation the understanding of its glacial history is however still limited a serious obstacle to obtain satisfactory paleoecological information has been the rarity of microfossil proxy species caused by high salinities here we present a continuous and well dated calcareous nannoplankton record from the northern red sea covering the interval from 60 14 5 ka bp our investigation shows that the composition of the calcareous nannoplankton community varied between 32 ka bp and 14 5 ka bp in response to rapid environmental changes which are closely correlated to climatic fluctuations described from the north atlantic region heinrich events h3 h2 and h1 are dominated by emiliania huxleyi gephyrocapsa oceanica and especially gephyrocapsa ericsonii are abundant between h3 h2 and h2 h1 a less pronounced response of the calcareous nannoplankton to the high latitudinal climatic oscillations is documented prior to 32 ka bp suggesting that a strong atmospheric coupling between the northern red sea and the north atlantic realm was established in the late marine isotope stage 3 in contrast to the previously held view of a sea level related salinity increase as the major cause for changes of the plankton communities within the glacial red sea we interpret the documented variations as being caused by local hydrographic changes under the atmospheric control from the extratropics temperature changes and especially variations of the water stratification appear to be critical selective factors for the calcareous nannoplankton composition

sensitivity studies of the red sea eddies using adjoint method the topography data is derived from general bathymetric chart of the oceans gebco https www gebco net the open boundary conditions are extracted from the estimating the circulation and climate of the ocean ecco product https ecco jpl nasa gov products the data supporting the analysis presented here can be found at figshare https figshare com articles data for 2018jc014531r 7243184 the research reported in this manuscript is supported by king abdullah university of science and technology kaust and made use of the resources of the supercomputing laboratory and computer clusters at kaust

troposphere planetary boundary layer interactions and the evolution of ocean surface density lessons from red sea corals a time series of oxygen isotope d18o measurements of a coral from the northern red sea rs is presented and used as a direct proxy for water surface density rs with a relatively constant subsurface density the generated surface density time series closely tracks water mass formation variability two positive and two negative high amplitude rs anomalies are studied and associated atmospheric and oceanic data are analyzed to understand large scale ocean atmosphere processes the dominant process is lower tropospheric subsidence it dries the boundary layer bl increases surface evaporation and rs and ultimately drives water mass formation the main cause of the subsidence is a temperature increase along the principal axis of the rs from the eastern mediterranean to the convergence zone cz 188 228n the increase entails isentropes sloping down to the southeast crossing pressure surfaces due to their tilt with nearly adiabatic flow along the principal axis air parcels move roughly along the sloped isentropes toward ever increasing pressure that is they subside the subsidence supplies the northern rs bl with upstream air from higher altitudes where humidity is low thus drying the bl the resultant high evaporation north of 258n with low evaporation minus precipitation south of 228n depresses sea levels in the northern rs and thus drives the rs thermohaline circulation and controls water mass formation excluded from the presented picture but probably very important is mixing with the hot dry air of the surrounding deserts

size segregation during aeolian saltation on sand dunes recent monte carlo computer simulations have modelled the local geometric mechanism by which mixed populations of differently sized particles order themselves when shaken such that larger particles rise at the expense of the smaller this process called size segregation is distinct from the mechanism of sifting where smaller particles fall between the interstices of larger particles size segregation is applied here to the sand grain populations found on the surfaces of dunes which are involved in a sorting process driven by the wind we present data from four barchan dunes located in the eastern province of saudi arabia a simple model is used to demonstrate that size segregation driven by saltation impacts is energetically plausible at the wind velocities typically encountered on dune surfaces laboratory tests which support this model are also discussed

mediterranean moisture source for an early holocene humid period in the northern red sea paleosalinity and terrigenous sediment input changes reconstructed on two sediment cores from the northernmost red sea were used to infer hydrological changes at the southern margin of the mediterranean climate zone during the holocene between approximately 9 25 and 7 25 thousand years ago about 3 per thousand reduced surface water salinities and enhanced fluvial sediment input suggest substantially higher rainfall and freshwater runoff which thereafter decreased to modern values the northern red sea humid interval is best explained by enhancement and southward extension of rainfall from mediterranean sources possibly involving strengthened early holocene arctic oscillation patterns and a regional monsoon type circulation induced by increased land sea temperature contrasts we conclude that afro asian monsoonal rains did not cross the subtropical desert zone during the early to mid holocene

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

on the branching of the kuroshio west of kyushu trajectories of satellite tracked surface drifters released in the continental margin area west of kyushu indicate a separation of the inshore side of the kuroshio that appears to form the beginning of the tsushima current the trajectories also indicate an anticyclonic sense of circulation in the area between the separated branch and the eastward directed kuroshio main stream consistent with long term geomagnetic electrokinetograph measurements of surface currents which show a broad southward flow along the west kyushu coast a theory is put forth that ties together these observed flow features in the theory the incidence is considered of an inertial current upon a step rise in topography characterized by a step depth of h0 to simulate the west kyushu coastal bathymetry in an f plane two layered inviscid ocean with a quiescent lower layer the inertial current is of a constant potential vorticity f h where h h0 is the undisturbed upper layer depth and is bounded inshore by a free streamline along which the upper layer depth is a constant hc h the steady state downstream configuration of a separation branch and a deflected main stream along the step is connected to the upstream approach current through the consideration of the constancy of the bernoulli function and the conservation of potential vorticity and mass in the immediate neighborhood of the incidence a complicated flow region is anticipated in which recirculation is featured and an anticyclonic gyre is expected further onto the step the volume integrated balance of along step momentum of the constant potential vorticity flow allows the determination of the angle the branch current makes with the step as a function of the angle of incidence and two depth ratios hc h and h0 h the bifurcation quotient defined as the ratio of the branch current transport to that of the approach current is found to be also such a function except it is independent of the incidence angle these functions yield results that are qualitatively in agreement with the observed bifurcation of the kuroshio west of kyushu that gives rise to the tsushima current

millennial scale variability in red sea circulation in response to holocene insolation forcing in order to assess how insolation driven climate change superimposed on sea level rise and millennial events influenced the red sea during the holocene we present new paleoceanographic records from two sediment cores to develop a comprehensive reconstruction of holocene circulation dynamics in the basin we show that the recovery of the planktonic foraminiferal fauna after the younger dryas was completed earlier in the northern than in the central red sea implying significant changes in the hydrological balance of the northern red sea region during the deglaciation in the early part of the holocene the environment of the red sea closely followed the development of the indian summer monsoon and was dominated by a circulation mode similar to the current summer circulation with low productivity throughout the central and northern red sea the climatic signal during the late holocene is dominated by a faunal transient event centered around 2 4 ka bp its timing corresponds to that of north atlantic bond event 2 and to a widespread regionally recorded dry period this faunal transient is characterized by a more productive foraminiferal fauna and can be explained by an intensification of the winter circulation mode and high evaporation the modern distribution pattern of planktonic foraminifera reflecting the prevailing circulation system was established after 1 7 ka bp

process modeling studies of physical mechanisms of the formation of an anticyclonic eddy in the central red sea surface drifters released in the central red sea during april 2010 detected a well defined anticyclonic eddy around 23 n this eddy was 45 60 km in radius with a swirl speed up to 0 5 m s the eddy feature was also evident in monthly averaged sea surface height fields and in current profiles measured on a cross isobath shipboard ctd adcp survey around that region the unstructured grid finite volume community ocean model fvcom was configured for the red sea and process studies were conducted to establish the conditions necessary for the eddy to form and to establish its robustness the model was capable of reproducing the observed anticyclonic eddy with the same location and size diagnosis of model results suggests that the eddy can be formed in a red sea that is subject to seasonally varying buoyancy forcing with no wind but that its location and structure are significantly altered by wind forcing initial distribution of water stratification and southward coastal flow from the upstream area momentum analysis indicates that the flow field of the eddy was in geostrophic balance with the baroclinic pressure gradient forcing about the same order of magnitude as the surface pressure gradient forcing

long time variation of soil co2 fluxes at the summit crater of vulcano italy here we report the first continuous data of geochemical parameters acquired directly from the active summit crater of vulcano this approach provides a means to better investigate deep geochemical processes associated with the degassing system of vulcano island in particular we report on soil co2 fluxes from the upper part of vulcano a closed conduit volcano from september 2007 to october 2010 large variations in the soil co2 and plume so2 fluxes order of magnitude coinciding with other discontinuous geochemical parameters co2 concentrations in fumarole gas and physical parameters increase of shallow seismic activity and fumarole temperatures have been recorded the results from this work suggest new prospects for strengthening geochemical monitoring of volcanic activity and for improving the constraints in the construction of a geochemical model this being a necessary condition to better understand the functioning of volcanic systems

new perspectives on volcano monitoring in a tropical environment continuous measurements of soil co2 flux at piton de la fournaise la reunion island france detecting renewal of volcanic activity is a challenging task and even more difficult in tropical settings continuous measurements of soil co2 flux were carried out at the piton de la fournaise volcano during 2013 2016 since this site is in the tropics periods of heavy rainfall are in the norm measurements covered volcanic unrest after a hiatus of 3 5 years we find that while temperature has the strongest effect extreme rainfall causes short term noise when corrected and filtered from the environmental influence soil co2 time series permit to detect a major deep magmatic event during march april 2014 three months before the first eruption of the new activity phase correlation with geophysical datasets allow timing of further stages of upward fluid ascent our study validates soil co2 flux monitoring in tropical environments as a valuable tool to monitor magma transfer and to enhance understanding of volcano unrest down to the lithospheric mantle

modes of subsurface intermediate and deep water renewal in the red sea a linear box model of the red sea is presented the model which inverts hydrographic and 3he data for the main features of the width integrated circulation is able to describe a large part of the seasonal and annual mean circulation by combining and reconciling major elements of current theories of the red sea circulation available flow measurements and tracer data the model provides a unified conceptual framework for the understanding of the circulation of the red sea the model forms deep water in the extreme north in two modes as first suggested by cember 1988 the convective mode renews the bottom water at an annual mean rate of 0 04 sv in the winter the isopycnal mode water renews the uppermost part of the deep water mass it flows to the south along the bottom of the pycnocline at an annual mean rate of 0 02 0 04 sv a new feature in the model s near surface circulation scheme is the ventilation of the thermocline in the winter at a mean rate of 0 04 sv also from the extreme north there is also a middepth return flow to the north at an annual mean rate of 0 07 sv this flow has been suggested but never rigorously quantified before

a coral oxygen isotope record from the northern red sea documenting nao enso and north pacific teleconnections on middle east climate variability since the year 1750 a 245 year coral oxygen isotope record from the northern red sea ras umm sidd egypt 28 n in bimonthly resolution is presented the mean annual coral 18o signal apparently reflects varying proportions of both sea surface temperature and 18oseawater variability in conjunction with instrumental observations of climate the coral record suggests for interannual and longer timescales that colder periods are accompanied by more arid conditions in the northern red sea but increased rainfall in the southeastern mediterranean whereas warmer periods are accompanied by decreased rainfall in the latter and less arid conditions in the northern red sea a 70 year oscillation of probably north atlantic origin dominates the coral time series interannual to interdecadal variability is correlated with instrumental indices of the north atlantic oscillation nao the el nino southern oscillation enso and north pacific climate variability the results suggest that these modes contributed consistently to middle east climate variability since at least 1750 preferentially at a period of 5 7 years

multicentennial scale hydrological changes in the black sea and northern red sea during the holocene and the arctic north atlantic oscillation 1 paleoenvironmental proxy data for ocean properties eolian sediment input and continental rainfall based on high resolution analyses of sediment cores from the southwestern black sea and the northernmost gulf of aqaba were used to infer hydroclimatic changes in northern anatolia and the northern red sea region during the last 7500 years pronounced and coherent multicentennial variations in these records reveal patterns that strongly resemble modern temperature and rainfall anomalies related to the arctic oscillation north atlantic oscillation ao nao these patterns suggest a prominent role of ao nao like atmospheric variability during the holocene beyond interannual to interdecadal timescales most likely originating from solar output changes

chemical features and isotopic composition of gaseous manifestations on vulcano island aeolian islands italy an interpretative model of fluid circulation abstract between 1987 and 1995 gases were sampled from various manifestations on vulcano island including various fumaroles at la fossa crater and baia di levante and diffuse soil gas emissions in several areas which are characterized by high c02 fluxes since the end of 1987 volcanic activity has increased considerably showing a marked rise in temperature 300 c in 1987 to 670 c in december 1992 and in output of steam from crater fumaroles in addition variations have been observed in the chemical and isotopic compositions of gases and thermal waters which can be attributed to an increased inflow of deeper fluids the isotopic composition of fumarolec steam seems to be the result of mixing processes between a positive endmember of deep origin d 10 15 18o 6 8 and two endmembers of meteoric origin with different oxygen shifts variations observed in the c02 isotopic composition suggest that all sampled manifestations are fed by a single deep source which may be magmatic such a source would be characterized by the 613cco2 values of high temperature fumaroles 13cco2 0 these values are noticeably more positive than those generally attributed to magmatic gases 13cco2 5 8 implying crustal contamination processes of the magma the observed decrease in 18oco2 values of the crater fumaroles from 20 in 1978 to between 12 and 15 in 1993 1994 was probably caused by two different processes the first is a reduction of the enrichment factor between c02 and h2o which is related to the increased temperature of the gases and the second is a mixing with more negative waters of meteoric origin finally c02 addition or removal processes caused by interactions between deep gases and shallow hydrothermal waters are likely to be responsible for the different chemical and isotopic compositions of gaseous emissions in the vulcano porto area and the crater fumaroles

volatiles and energy released by purace volcano total co2 output of purace volcano colombia was estimated on the basis of fluids discharged by fumaroles soil gases and dissolved carbon species in the aquifer the soil co2 emission was computed from a field survey of 512 points of co2 soil flux measurements at the main degassing areas of purace volcano the co2 flux from purace s plume was estimated using an indirect method that used the so2 plume flux and co2 so2 ratio of the main high temperature fumarole the total output of co2 was estimated at 1500 t day the main contribution of co2 comes from the plume summit degassing and from soil degassing that emit 673 and 812 t day respectively the contributions of summit and soil degassing areas are comparable indicating an intermediate degassing style partitioned between closed and open conduit systems the estimated water vapor discharge as derived from the chemical composition of the fumaroles the h2o co2 ratio and the so2 plume flux allowed calculation of the total thermal energy fumarolic soil degassing and aquifer released from the purace volcanic system this was 360 mw

high resolution onshore seismic imaging of complex volcanic structures an example from vulcano island italy 1 detailed seismic images of subsurface structures of volcanic calderas are fundamental to improve the structural and volcanological knowledge of these high risk volcanoes however high quality seismic data are difficult to obtain in volcanic areas especially on shore we report the results of a high resolution seismic profiling of the western sector of la fossa caldera vulcano island italy using a high resolution vibrating source and both alternative acquisition and processing techniques we were able to overcome most of the inconvenience caused by volcanic lithotypes this study provides the subsurface distribution of volcanic deposits as well as the recognition of some significant intracaldera structures we located a parasitic vent or hyaloclastite mound buried under la fossa caldera which is dissipating co2 in an area where earthquakes have been recorded at about 1 km depth furthermore the deformation pattern found at the southernmost part of the profile is consistent with a caldera collapse after a dome intrusion the results suggest that the use of high resolution vibrating sources combined with alternative seismic acquisition techniques and nonconventional processing could help to recover detailed information on the shallow structures of volcanic areas

on the sources formation and circulation of red sea deep water red sea deep water is renewed from sources in the far north of the red sea upwelling of deep water throughout the basin maintains the sharp pycnocline with its base near the depth of the sill at bab el mandeb before now deep water renewal was thought to occur mainly by means of convective deep water formation in the north which renews the bottom water and gives rise to a southward flowing bottom current carbon 14 and 3he data from the geosecs indian ocean expedition lead to the identification of an additional volumetrically larger mode of northern deep water formation in which new deep water is injected immediately beneath the pycnocline this mode of deep water formation to be called the isopycnal mode also gives rise to a southward flowing current in this case at the top of the deep water mass geosecs data also demonstrate the existence at intermediate depths in the deep water of a return flow to the north the surface history in the nuclear era of the 14c in the deep water source region was reconstructed by direct radiocarbon measurements on annual growth bands of corals calculation then shows that new deep water forms in the convective mode at a rate of 0 05 0 01 sverdrup sv expressed as if the flow were continuous and is due principally to processes occurring in the mouth of the gulf of suez the injection beneath the pycnocline of new deep water formed in the isopycnal mode is 0 11 0 02 sv this new deep water appears to originate mainly in the extreme open northern red sea the gulf of aqaba makes a modest but significant contribution to both modes the total deep water renewal rate is about 0 16 sv yielding a bulk deep water residence time of about 36 years oxygen consumption in the deep water shows approximately exponential decrease of consumption rate with depth as expected on geological and geophysical grounds hydrographically significant fluxes of heat and salt from the sea floor into the red sea deep water are discernible in the hydrography helium 3 flux from the sea floor into the deep water is about 69 1 stp year

the evolution of a dynamic geological system the support of a gis for geochemical measurements at the fumarole field of vulcano italy abstract the island of vulcano aeolian arc southern italy has displayed several periods of volcanic unrest since the end of the last eruption 1890 we report here results obtained from a long term survey concerning variations of both the steam output and the exhaling surface area at the summit crater fumarolic field of la fossa the field measurements analysed in a geographical information system gis show a highly dynamic volcanic system in which deep variations in the geochemistry and the temperature of the released fluids were accompanied by fluctuations in the mass output of steam and the topography of the crater field the use of a gis facilitated digitized reconstructions of maps of the crater field in addition to analysis of the steam flux data the fumarolic field expanded its surface area from 50 m 2 in 1983 to more than 2400 m 2 in 1995 accompanied by an increase in steam output from 152 to about 1400 tonnes per day the possibility that the observed phenomena are related to volcano tectonic activity and to magma uprising is taken into consideration

temporal variations in air permeability and soil co2 flux in volcanic ash soils island of vulcano italy air permeability is a major physical factor affecting the advective transport of a gas through the soil and variations in this parameter can strongly influence the emission of endogenous gases from the soil to the atmosphere in this paper we illustrated a new and simple method for measuring in situ air permeability based on the measurement of air pressure inside a special probe inserted into the soil the method was designed and developed primarily to study the relationship between air permeability and the soil co2 flux in an active volcanic area the method was used for continuous monitoring of the air permeability at two different locations on the island of vulcano at the same time the values of the atmospheric pressure temperature rain and volumetric water content of the soil were also acquired to investigate their effect on soil air permeability and soil co2 flux the results showed that during the monitoring period soil air permeability exhibited minor variations at each site while larger variations in the soil co2 flux were recorded the effect of soil air permeability on soil co2 flux was negligible at both sites whereas a strong dependence of soil co2 flux on volumetric water content and on atmospheric pressure was found furthermore the variation in air permeability recorded at both sites was much lower than that predicted using some well known predictive models showing that the relationship among different soil transport parameters is more complex in real field conditions than would be expected by semiempirical models

impact of late quaternary environmental changes on deep sea benthic foraminiferal faunas of the red sea abstract fluctuations in abundance diversity and species composition of benthic foraminifera from two sites of the northern and southern red sea indicate strong variability of deep sea ecosystems during the last four glacial to interglacial cycles in total five and four different benthic foraminiferal assemblages have been identified in the northern core and southern core respectively comparison with recent faunas from the red sea and adjacent oceans allowed the reconstruction of temporal changes in deep water ventilation salinity and food availability at the seafloor generally the abundance of infaunal and miliolid taxa increase during glacial intervals indicating increased organic matter fluxes oxygen decrease and salinity increase in deep waters during these times these fluctuations are attributed to enhanced oxygen consumption rates and temporarily reduced deep water formation in the northern red sea during glacial intervals the recorded environmental changes are a reflection of both high and low latitude climate changes the northern red sea is mainly influenced by glacio eustatic sea level fluctuations that control deep water formation rates and by mid latitude climate changes of the mediterranean region that control surface productivity in contrast deep sea ecosystem variability of the southern red sea is additionally influenced by low latitude climate changes attributed to the ne monsoon intensity that drives the inflow of nutrient rich surface waters from the gulf of aden these results demonstrate the high sensitivity of deep sea ecosystems of the red sea to both global and regional climate changes

physical and biological characteristics of the winter summer transition in the central red sea the central red sea crs lies between two distinct hydrographic and atmospheric regimes in the southern red sea seasonal monsoon reversal regulates the exchange of water between the red sea and the indian ocean in the northern red sea intermediate and occasionally deep water are formed during winter to sustain the basin s overturning circulation highly variable mesoscale eddies and the northward flowing eastern boundary current ebc determine the physical and biogeochemical characteristics of the crs ship based and glider observations in the crs between march and june 2013 capture key features of the transition from winter to summer and depict the impact of the eddy activity on the ebc flow less saline and relatively warmer water of indian ocean origin reaches the crs via the ebc initially an anticyclonic eddy with diameter of 140km penetrating to 150m depth with maximum velocities up to 30 35 cm s 1 prevails in the crs this anticyclonic eddy appears to block or at least redirect the northward flow of the ebc dissipation of the eddy permits the near coastal northward flow of the ebc and gives place to a smaller cyclonic eddy with a diameter of about 50km penetrating to 200m depth by the end of may as the northerly winds become stronger and persistent throughout the basin characteristic of the summer southwest monsoon wind regime the ebc and its associated lower salinity water became less evident replaced by the saltier surface water that characterizes the onset of the summer stratification in the crs

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

the episodic and abrupt geochemical changes at la fossa fumaroles vulcano island italy and related constraints on the dynamics structure and compositions of the magmatic system abstract herein we report on the chemical and isotopic c h o and he compositions of the fluids from la fossa crater fumaroles of vulcano from 1999 to 2010 consistent with records obtained since the end of the 1980s our data show that the geochemical features of the fumarole system have experienced several episodes of remarkable change each lasting no more than a few months typical signatures of these short term anomalies are large increments in co 2 n 2 and he concentrations coupled to increased 13 c 12 c isotopic ratios but their meaning remains widely debated within a model of fumarolic fluids based on mixing between hydrothermal and magmatic endmembers we have developed a novel approach to constrain chemical he co 2 and n 2 he and isotopic 13 c 12 c d h and 3 he 4 he ratios of the magmatic endmember during the short term anomalies although much of the geochemical variability in fumaroles results from changes in mixing proportions the magmatic fluid unquestionably shows significant variations in time the magmatic he co 2 n 2 he 13 c 12 c and 3 he 4 he values throughout 1988 1996 differed from those feeding the anomaly at the end of 2004 early clues of the new magmatic fluid appeared in 1998 1999 far from any short term anomaly whereas new and old magmatic fluids coexisted after 2004 we quantitatively prove that the detected geochemical changes are consistent with the degassing path of a magma having a latitic composition and suggest the presence of two magma ponding levels at slightly different pressures where bubble melt decoupling can occur the different he isotope compositions at these levels suggest low hydraulic connectivity typical of a complex reservoir with dike and sill structures in this framework the short term geochemical anomalies are probably due to gas accumulation at the top of magma bodies followed by massive escape or activation of new degassing levels in the reservoir for which the stress field almost certainly plays a key role such a scenario explains the observed increases in both fumarole output and shallow high frequency seismicity due to increased pore pressure during the anomalies while being consistent with the concomitant absence of any deep seismicity or ground deformation eventually related to magma movement

time series analysis of high temperature fumaroles monitored on the island of vulcano aeolian archipelago italy abstract the exhalation activity at the la fossa cone vulcano island aeolian archipelago italy has been ongoing for more than 1 century many of the monitored geochemical and geophysical parameters have showed transient variations of energy release the time series analyses of fumarole temperatures presented in this paper enabled the sequence of observations to be defined and information from different monitoring stations to be integrated the motion of fluids feeding the fumaroles of the la fossa cone is driven by the thermal and kinetic energies that balance the seismic and volcanic forces active in the region and the temperatures of the fumaroles reflect the local response of the hydrothermal system to these forces during a 14 year period of observation from 1998 to 2012 fumarole temperatures showed various trends but also cyclic variations characterized by sharp increases the repetition of these variations during periods with different trends indicates that no physical variation occurred from the hydrothermal source to the surface during the analyzed period and after each periodic geochemical crisis the previous thermal conditions were restored although the continuous monitoring of high temperature fumaroles was limited to only a few sites the observed trends characterized the most important fumaroles in the area of vulcano island an evaluation of thermal energy release based on these spatially discrete measurements would be a speculative exercise in thermodynamics but the analyses of the recorded data represent a step forward in interpreting the signals from ongoing volcanic activity and in assessing the seismic risk

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

environmental influences on soil co2 degassing at furnas and fogo volcanoes sao miguel island azores archipelago abstract since october 2001 four soil co 2 flux stations were installed in the island of sao miguel azores archipelago at fogo and furnas quiescent central volcanoes these stations perform measurements by the accumulation chamber method and as the gas flux may be influenced by external variables the stations are equipped with several meteorological sensors multivariate regression analysis applied to the large datasets obtained allowed observing that the meteorological variables may influence the soil co 2 flux oscillations from 18 to 50 5 at the different monitoring sites additionally it was observed that meteorological variables mainly soil water content barometric pressure wind speed and rainfall play a different role in the control of the gas flux depending on the selected monitoring site and may cause significant short term spike like fluctuations these divergences may be potentially explained by the porosity and hydraulic conductivity of the soils topographic effects drainage area and different exposure of the monitoring sites to the weather conditions seasonal effects are responsible for long term oscillations on the gas flux before a reliable application of soil co 2 flux to seismic and or volcanic monitoring it is important to recognize those environmental influences on the gas flux in addition understanding the external meteorological influences on the gas flux may be important for the public health risk assessment since meteorological parameters may cause also significant indoor co 2 increases in a house at furnas village in furnas volcano caldera the values detected reached percentages as high as 20 8 due to significant decreases in the barometric pressure

climatic changes in the northern red sea during the last 22 000 years as recorded by calcareous nannofossils 1 we present a high resolution record of calcareous nannofossils from the northern red sea for the last 22 kyr extreme conditions with enhanced salinities during the last glacial maximum are characterized by high values of gephyrocapsa ericsonii the dominance of emiliania huxleyi in heinrich event 1 indicates a climatic cooling favoring the bloom of opportunistic species the calcareous nannofossils record a two step onset of the postglacial humid climate punctuated by the younger dryas both steps show an early oligotrophic phase dominated by florisphaera profunda and gladiolithus flabellatus and a subsequent fertile phase characterized by e huxleyi the younger dryas is described by high values of gephyrocapsa oceanica indicating an increased mixing of the water column in the late holocene repetitive increases in abundance of f profunda and g flabellatus reflect restricted oligotrophic conditions caused by the high aridity following the holocene humid period

volcanic steam output directly measured in fumaroles the observed variations at vulcano island italy between 1983 and 1987 the mass of steam emitted by the fumaroles of the crater of vulcano aeolian islands italy was evaluated by using a direct measuring method measurements were effected with this method between 1983 and 1987 in nine field campaigns the results of which are given in this paper the steam flux measurements were performed by an instrument expressly designed for steam condensation the estimates of the thermal energy transported daily by the steam gave values of up to 10e12 j the sharp variations in the total mass outputs recorded in 1984 and 1985 are here interpreted as being a consequence of the probable accumulation of fluid pressure at depth during the evolution of volcanic activity the different results obtained from the various areas of the fumarolic field during the evolutionary phases have led to the hypothesis that different subsystems exist that feed the fumaroles and that their activity is triggered by volcano tectonics this method can be applied in the evaluation of both fumarolic steam and thermal energy outputs and therefore it is particularly useful in geothermal exploration in the evaluation of the environmental impact of volcanic degassing and in the forecasting of volcanic eruptions the evaluation of the steam output is also useful for quantifying the release of other gaseous species and giving univocal interpretations regarding their variations in concentrations furthermore this direct method provides a new way of calibrating the flux estimates effected by other telemetric techniques lidar cospec etc

in situ permeability measurements based on a radial gas advection model relationships between soil permeability and diffuse co2 degassing in volcanic areas in this paper we have developed a new method for measuring in situ soil permeability which is based on the theory of radial gas advection through an isotropic porous medium the method was tested in the laboratory and at several locations on the island of vulcano aeolian islands italy it consists of a special device which generates a gas source at a depth of 50 cm and it permits measurement of the relative induced pressure in nearby soil at different depths the characteristic error of the method was less than 10 furthermore soil permeability measurements were carried out in the island of vulcano during different periods of the year between may 2000 and june 2001 a strong decrease in permeability in the upper layers of the soil during and after rainfall was noted with very poor correlations between the spatial distributions of soil co2 flux and shallow soil permeability

seasonal overturning circulation in the red sea 1 model validation and summer circulation the overturning circulation in the red sea exhibits a distinct seasonally reversing pattern and is studied using high resolution mit general circulation model simulations in the first part of this study the vertical and horizontal structure of the summer overturning circulation and its dynamical mechanisms are presented from the model results the seasonal water exchange in the strait of bab el mandeb is successfully simulated and the structures of the intruding subsurface gulf of aden intermediate water are in good agreement with summer observations in 2011 the model results suggest that the summer overturning circulation is driven by the combined effect of the shoaling of the thermocline in the gulf of aden resulting from remote winds in the arabian sea and an upward surface slope from the red sea to the gulf of aden set up by local surface winds in the red sea in addition during late summer two processes associated respectively with latitudinally differential heating and increased salinity in the southern red sea act together to cause the reversal of the contrast of the vertical density structure and the cessation of the summer overturning circulation dynamically the subsurface northward pressure gradient force is mainly balanced by vertical viscosity resulting from the vertical shear and boundary friction in the strait of bab el mandeb unlike some previous studies the three layer summer exchange flows in the strait of bab el mandeb do not appear to be hydraulically controlled

seismic events at vulcano italy during 1988 1992 abstract a classification of seismic events is proposed that originate on vulcano aeolian islands southern tyrrhenian sea and adjacent regions into four broad classes 1 shocks that exhibit single peaked spectra 2 typical earthquakes with distinct p and s phases 3 irregular shaped events with ill defined to undetectable s phases and 4 long period events with dominant frequency peak less than 2 hz a hypothesis is put forward that the shocks occurring within the volcanic cone of la fossa are mainly related to intense fumarolic activity of high temperature more than 650 c in october 1992 estimation of seismic energy release within two distinct sectors one including la fossa cone the other external to it during 1988 1992 has been developed in order to evaluate the level of seismic activity of the system over the time here analysed the rate of seismic energy density release at la fossa was 4 71 1014 erg km 2 yr 1 that is significantly larger than that of the surrounding areas furthermore the energy partition estimate indicates that within la fossa seismic energy release associated with rock failure processes is on the whole about 3 6 times larger than that of fluid driven shocks the latter appear to be concentrated at rather shallow depths 400 1000 m where geochemical analyses and geothermal surveys indicate the sealing action of hydrothermal minerals estimated b values of the gutenberg richter magnitude frequency relation range between 0 81 0 27 and 1 45 0 29 within la fossa whereas a value around 1 6 has been calculated for the external sector the comparison between data presented in this paper and those from recent geophyical and geochemical investigations shows that appreciable increments in the rate of seismicity are accompanied with significant modifications in the chemistry of fumarolic gases and in the ground deformation pattern recorded at the base of the active cone

cluster analysis of soil co2 data from mt etna italy reveals volcanic influences on temporal and spatial patterns of degassing soil co2 concentration data were collected periodically from july 2001 to june 2005 from sampling site grids in two areas located on the lower flanks of mt etna volcano paterno and zafferana etnea santa venerina cluster analysis was performed on the acquired data in order to identify possible groups of sites where soil degassing could be fed by different sources in both areas three clusters were recognised whose average co2 concentration values throughout the whole study period remained significantly different from one another the clusters with the lowest co2 concentrations showed time averaged values ranging from 980 to 1 170 ppm vol whereas those with intermediate co2 concentrations showed time averaged values ranging from 1 400 to 2 320 ppm vol and those with the highest concentrations showed time averaged values between 1 960 and 55 430 ppm vol we attribute the lowest co2 concentrations largely to a biogenic source of co2 conversely the highest co2 concentrations are attributed to a magmatic source whereas the intermediate values are due to a variable mixing of the two sources described above the spatial distribution of the co2 values related to the magmatic source define a clear direction of anomalous degassing in the zafferana etnea santa venerina area which we attribute to the presence of a hidden fault whereas in the paterno area no such oriented anomalies were observed probably because of the lower permeability of local soil time series analysis shows that most of the variations observed in the soil co2 data from both areas were related to changes in the volcanic activity of mt etna seasonal influences were only observed in the time patterns of the clusters characterised by low co2 concentrations and no significant interdependence was found between soil co2 concentrations and meteorological parameters the largest observed temporal anomalies are interpreted as release of co2 from magma batches that migrated from deeper to shallower portions of etna s feeder system the pattern of occurrence of such episodes of anomalous gas release during the observation period was quite different between the two studied areas this pattern highlighted an evident change in the mechanism of magma transport and storage within the volcano s feeder system after june 2003 interpreted as magma accumulation into a shallow 8 km depth reservoir

multiparametric approach in investigating volcano hydrothermal systems the case study of vulcano aeolian islands italy seismic activity ground deformation and soil and fumarole temperatures acquired during 2004 2007 at vulcano aeolian islands are analysed and the time relations among the different time series are discussed changes in temperature of fumarolic gases took place during four anomalous periods november 2004 march 2005 october 2005 february 2006 august october 2006 july december 2007 at the same time as an increasing number of volcano seismic events in particular the temperatures at high temperature vents and at steam heated soil ranged in time from 180 to 440 c and from 20 to 90 c respectively the maximum daily number of volcano seismic events was 57 reached during the second anomalous period this seismicity characterised by focal depth generally lower than 1 km below sea level b s l and composed of different kinds of events associated to both resonance and shear failure processes is related to the shallow dynamics of the hydrothermal system during the analysed period very few volcano tectonic earthquakes took place and tilt recordings showed no sharp or important changes in light of such observations the increases in both temperature and volcano seismic events number were associated to increases in the release of gas from a deep and stable magma body without magma intrusions within the shallow hydrothermal system indeed a greater release of gas from depth leads to increased fluid circulation that can promote increases in volcano seismic events number by both fracturing processes and resonance and vibration in cracks and conduits the different trends observed in the measured geochemical and geophysical series during the anomalous periods can be due to either time changes in the medium permeability or a changing speed of gas release from a deep magma body finally all the observed variations together with the changing temporal distribution of the different seismic event kinds suggest that the hydrothermal system at vulcano can be considered unsteady and dynamic

on the crossover of boundary currents in an idealized model of the red sea the west to east crossover ofboundarycurrents has been seen in mean circulationschemes fromseveral past models of the red sea this study investigates the mechanisms that produce and control the crossover in an idealized eddy resolving numerical model of the red sea the authors also review the observational evidence and derive an analytical estimate for the crossover latitude the surface buoyancy loss increases northward in the idealized model and the resultant mean circulation consists of an anticyclonic gyre in the south and a cyclonicgyreinthenorth in themidbasin thenorthwardsurfaceflow crossesfromthewestern boundarytothe eastern boundary numerical experiments with different parameters indicate that the crossover latitude of the boundary currents changes with f0 b and the meridional gradient of surface buoyancy forcing in the analytical estimate which is based on quasigeostrophic b plane dynamics the crossover is predicted to lie at the latitude where the net potential vorticity advection including an eddy component is zero various terms in the potential vorticity budget can be estimated using a buoyancy budget a thermal wind balance and a parameterization of baroclinic instability

multiple hazards and paths to eruptions a review of the volcanic system of vulcano aeolian islands italy abstract vulcano is one of the 7 volcanic islands and 6 seamounts forming the aeolian volcanic district italy vulcano has a long eruptive record and its last eruption 1888 90 originated the definition of the vulcanian eruptive style like most volcanic islands vulcano generates many potentially interconnected hazards determining a potentially high risk here we review the state of knowledge on its geology eruptive activity historical accounts structural setting geophysical and geochemical surveillance and available hazard quantifications in order to have an updated picture of the state knowledge on volcanic hazard we follow a prototypal reviewing scheme based on three standardized steps i review of the volcanic system ii review of available eruptive and non eruptive hazard quantifications iii development of a conceptual interpretative model we find that while a rather vast literature is dedicated to the volcanic system of vulcano and the reconstruction of past events few quantitative hazard assessments exist in addition the range of natural variability considered for each hazard is potentially underestimated e g limited range of considered eruption magnitude and style and of vent position as it is the potential effect of multi hazard impact the developed conceptual model for the feeding system provides a synthetic picture of the present knowledge about the system as emerged from the review in addition it allows for the identification of potential paths to eruption and provides a first order link among the main hazards this review provides an up to date snapshot of existing knowledge on volcanic hazard at vulcano on which to build future hazard quantifications as well as to support present and future decision making

investigating the deepest part of a volcano plumbing system evidence for an active magma path below the western flank of piton de la fournaise la reunion island abstract peripheral diffuse degassing of co 2 from the soil occurs across the western flank of piton de la fournaise volcano la reunion island indian ocean along a narrow zone in this area carbon isotopic analysis on soil gas samples highlights significant mixing between magmatic and organic end members the zones with the strongest magmatic signature highest 13 c overlap spatial distribution of hypocenters recorded shortly before and during volcano reactivation and allow discriminating a n135 degassing lineament with a minimum length of 11 km and 140 20 m width such orientation is in accordance with that of an old dyke network along the rift zone and with n120 130 and n140 155 lineaments related to the inheritance of oceanic lithosphere structures our findings show that this n135 lineament represents a preferential magmatic pathway for deep magma transfer below the volcano flank moreover spatial distributions of recent eccentric cones indicate a well founded possibility that future eruptions may by pass the shallow plumbing system of the central area of the volcano taking a lateral pathway along this structure our results also confirm that piton de la fournaise activity is linked to a laterally shifted plumbing system and represent a major improvement in identifying the main high risk area on the densely populated western flank of the volcano

climatological coastal jet collision intermediate water formation and the general circulation of the red sea the authors present climatologies of a numerical model of the red sea focusing on the dynamics of winter intermediate water formation northward flowing boundary currents are identified as the major dynamical elements at the northern boundary the eastern current follows the geometry eventually turning back to the south at 268n and the western wall the two boundary currents collide at the collision site the denser eastern current subducts under the western boundary current the subduction forces the western boundary current eastward into the interior convection communicates the surface fluxes to the downwelled plume and intermediate water forms the estimated rate 0 11 sv sv 106 m3 s21 agrees with previous estimates the authors identify basin scale sea surface tilt to the north due to variable thermohaline forcings as the key dynamical variable the resultant geostrophic eastward cross channel flow interacts with the boundaries and creates upwelling and surface topography spatial patterns that drive the coastal jets upwelling induced vortex stretching dominates the vorticity balance and governs the separation of the western boundary current from the western wall the process ceases in the summer

preservation of siliceous microplankton in surface sediments of the northern red sea abstract we studied the siliceous microplankton assemblages mainly diatoms from plankton tows mesh size 20 m and surface sediment samples collected along a n s transect in the northern red sea 28 21 n in addition we analyzed differences similarities between plankton and sediment assemblages within a brine filled basin the southern basin of the shaban deep and compared these assemblages with those from outside the brine plankton samples revealed the overwhelming dominance of diatoms over other siliceous groups diatoms accounted for ca 97 of all biosiliceous particles at 120 20 m vs 2 9 silicoflagellates and 0 4 radiolarians and ca 94 at 200 120 m vs 4 5 silicoflagellates and 1 6 radiolarians in general a marine warm water tropical subtropical diatom assemblage characterizes the plankton samples representatives of the nitzschia bicapitata group are by far the most abundant contributors at both depth intervals average 43 ranging from ca 30 in the north to ca 60 in the south biogenic opal content in non brine surface sediments is very low below 0 2 wt sio2 and concentration of siliceous microorganisms is also low and of the order of 5 103 104 microorganisms g 1 dry sediment diatoms are the main contributors to the opal signal in the 20 40 m fraction while they share dominance with radiolarians in the 40 m fraction total diatom concentrations average 1 2 104 valves g 1 in the 20 40 m fraction and 4 103 valves g 1 in the 40 m fraction robust taxa of warm water affinity alveus marinus azpeitia neocrenulata azpeitia nodulifera and roperia tesselata characterize the surface sediments in contrast biogenic opal content in brine surface sediment samples is much higher than in the non brine samples ranging from 2 8 to 3 8 wt sio2 and concentration of siliceous microorganisms is 3 4 orders of magnitude higher in addition here diatoms dominate the opal signal the taxa found in these samples are a mixture of non brine and plankton samples and fragile forms e g n bicapitata group neodelphineis indica are well preserved in these sediments thus brine sediments in this region seem to offer a great potential for palaeoenvironmental studies

time space variation of volcano seismic events at la fossa vulcano aeolian islands italy new insights into seismic sources in a hydrothermal system we investigated the relationship between volcano seismic events recorded at la fossa crater of vulcano aeolian islands italy during 2004 2006 and the dynamics of the hydrothermal system during the period of study three episodes of increasing numbers of volcano seismic events took place at the same time as geothermal and geochemical anomalies were observed these geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids three classes of seismic events long period high frequency and monochromatic events characterised by different spectral content and various similarity of the waveforms have been recognised these events clustered mainly below la fossa crater area at depths of 0 5 1 1 km b s l were space distributed according to the classes based on their features we can infer that such events at vulcano are related to two different source mechanisms 1 fracturing processes of rocks and 2 resonance of cracks or conduits filled with hydrothermal fluid in the light of these source mechanisms the increase in the number of events at the same time as geochemical and geothermal anomalies were observed was interpreted as the result of an increasing magmatic component of the hydrothermal fluids implying an increase of their flux indeed such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids increased pore pressures gave rise to fracturing processes while the increased fluid flux favoured resonance and vibration processes in cracks and conduits finally a gradual temporal variation of the waveform of the hybrid events one of the subclasses of long period events was observed likely caused by heating and drying of the hydrothermal system

hydraulic interpretation of direct velocity measurements in the bab al mandab abstract acoustic doppler current profiler velocity measurements in the bab al mandab during the period june 1995 march 1996 are used to assess the hydraulic character of the exchange flow the strait is 150 km long and contains two distinct geometrical choke points the hanish sill and perim narrows the authors use a three layer approximation of the monthly mean velocity and density structure at the sill and narrows to calculate the phase speeds of the first and second internal long gravity waves the first second mode is generally characterized by in phase out of phase motions of the two interfaces the calculations take cross strait topographic variations into consideration by using a piecewise linear representation of the actual bottom the resulting phase speeds are used to determine whether the flow is subcritical supercritical or critical with respect to the first and second modes subcritical supercritical means that the two wave pairs corresponding to a given mode propagate in opposite

arctic oscillation signature in a red sea coral we show that the winter time series of the ras umm sidd coral oxygen isotope record from the northern red sea approximately 28 n is linked to the arctic oscillation phenomenon the northern hemisphere s dominant mode of atmospheric variability until now the detection of this mode which is most prominent in winter in proxy climate records was difficult due to the lack of a clear seasonality in most paleoclimatic archives the results suggest that northern red sea corals can provide information about the low frequency variability of the northern hemisphere winter circulation during the pre instrumental period

mapping fumarolic fields in volcanic areas a methodological approach based on the case study of la fossa cone vulcano island italy abstract changes in the activity state of a volcano can be inferred by monitoring the steam flux from fumarolic fields in terms of 4d x y z time variations in temperature and extension of the zone during the last decades several studies in this field have been conducted worldwide and at vulcano island italy in particular both direct and remotely sensed measurements have been used for identifying thermally anomalous areas but the possible role of the hydrothermal alteration of volcanic products producing a sealing effect that obscures the surface thermal evidence of fumarolic activity have never been explored the novelty of the present study carried out at la fossa cone vulcano island was the integration of direct and remotely sensed temperature measurements with the evaluation of soil permeability for the precise mapping of areas where shallow hydrothermal circulation could occur even in the absence of surface evidence the main results of this study concern the role of a coating found on rock surfaces and regolith in introducing mapping errors especially during diachronic temperature surveys based on remotely sensed measurements

long term monitoring on a closed conduit volcano a 25 year long time series of temperatures recorded at la fossa cone vulcano island italy ranging from 250 c to 520 c abstract the longest record of temperature data from an active volcano in southern italy is presented the dataset comes from continuous monitoring of fumarole temperatures from the la fossa cone of vulcano aeolian islands running from 1991 to 2016 the discussion includes an empirical approach based on a large number of direct measurements at vulcano island geochemical monitoring of the uprising fluids allows detection of the surface effects of perturbation in the state variables of the buried hydrothermal and magmatic systems the presented datasets show that fumaroles changing temperatures which are related to surface heat flow are useful indicators over the past 25 years the combined effects of runoff and chemo physical alterations were negligible on the output temperature of the earliest monitored fumaroles the maximum recorded variation was 298 c measured in the ground very close to the steaming vents at a depth of 0 5 m repetition of output temperature values occurred after 19 years in the same position the time variations suggest a cyclic characteristic although more years are needed to register the complete cyclic modulation a combination of minor cyclical variations has also been registered in the fumarole output the minor cycles appeared in this long series of data after 1995 and they can be interpreted as one of the surface effects of temporary departures from a stationary state assumed for the system feeding the la fossa area in this sector of the mediterranean area the steady state pressure field as well as the steady state temperature gradients can be perturbed either by magmatism or by seismo tectonic processes related to regional dynamics this long term monitoring allowed comparisons of many temperature subsets with other validated geochemical and geophysical data series and highlighted common source mechanisms accounting for endogenous processes changes in the magma source and or seismo tectonic activity have been the primary causes of the time variations the collected data show the effectiveness of the geochemical approach for following the heat flow changes that originated from a deep source in real time even though an estimation of magmatic and or hydrothermal energy release cannot be retrieved by surface temperature monitoring alone

joint analysis of electric and gravimetric data for volcano monitoring application to data acquired at vulcano island southern italy from 1993 to 1996 abstract understanding the dynamics of volcanic hydrothermal systems is a key factor for discriminating between magmatic and hydrothermal nature of the sources responsible for the unrest phenomena observed in active volcanic areas numerous studies of geophysical data monitoring in volcano geothermal districts has indeed proven that close relationships exist between the volcanic and hydrothermal fluid circulation and the anomalous geophysical signals observed at the ground surface in this paper a simultaneous analysis that integrates resistivity and gravity data is suggested as a useful tool to infer a consistent conceptual model of hydrothermal volcanic systems and their evolution an application of the proposed analysis to repeated resistivity and gravity measurements performed on vulcano island aeolian archipelago sicily southern italy is presented with the aim of gaining information on the dynamics of the volcanic hydrothermal system the examined period ranges from december 1993 to september 1996 when significant changes in chemical properties temperatures and emission rates of la fossa crater fumaroles were observed all indicating an increase in the flux of hot deep magmatic gases the results of our analysis which refers to a profile located at the foot of the northwest flank of la fossa cone suggest that underground cyclic water to vapour transformations govern the shallow hydrothermal system dynamics generally described by a negative correlation between the monitored resistivity and gravity data the occurrence of positive correlations between the two analysed parameters could be ascribed to volcanic dynamics which would mask the normal hydrological and hydrothermal system behaviour

an innovative method for continuous measurement of soil co2 flux abstract herein we present a method for continuous measurement of soil co 2 flux that is completely new and distinct from existing instruments the foremost difference is that instead of using an infrared gas analyser irga the new device measures soil co 2 flux by means of a simple pressure sensor measuring pressure transients inside a closed polymeric tube inserted into the soil this allows continuous measurements even in soil placed in environments that could potentially damage irga in addition due to the innovative operating principle measurements of soil co 2 flux can be effortlessly performed also in strongly harsh weather conditions theoretical equations were derived for calculating soil co 2 flux solely using measured transient values the reliability of the equations was rigorously tested with a variety of experiments continuous measurements over four months acquired in a high emission area on the island of vulcano compared favourably with the data obtained using an established method

seasonal overturning circulation in the red sea 2 winter circulation author posting 0american geophysical union 2014 this article is posted here by permission of american geophysical union for personal use not for redistribution the definitive version was published in journal of geophysical research oceans 119 2014 2263 2289 doi 10 1002 2013jc009331

spatial domain analysis of carbon dioxide from soils on vulcano island implications for co2 output evaluation abstract the carbon dioxide emissions of volcanoes have been targeted as effective contributors of co 2 to the atmosphere however different sources can be effective and active at the same time in the generation and release of co 2 in volcanic zones since isotopic fingerprinting of co 2 allows the precise identification of different sources coupling carbon isotope and co 2 flux measurements enables the evaluation of the mass contribution of each source to the carbon dioxide emissions this paper accounts for the first extensive spatial analysis of coupled measurements of carbon isotopologues of co 2 in the soil gases and co 2 fluxes discharged by soils on vulcano island an innovative method has been designed tested and fine tuned in the laboratory to measure 13 c co 2 values directly in field using a new type of laser based isotopologues analyzer namely a deltaray thermo fisher scientific the method can be used to determine the carbon isotope composition across the full range of co 2 concentrations in the soil gases 0 100 vol these data have been combined with measurements of the co 2 contents in the soil gases to distinguish co 2 from deep origins from co 2 of biogenic origin in the inhabited area of vulcano porto the method of evaluating the amount of deep origin co 2 in the soil gases is widely applicable in volcanic and geothermal zones for evaluation and monitoring purposes for both gas and volcanic hazards

diffuse co2 soil degassing and co2 and h2s concentrations in air and related hazards at vulcano island aeolian arc italy ingv dpc programme project v5 diffuse degassing in italy airplane firb project of the italian ministry of the university and research

a pronounced dry event recorded around 4 2 ka in brine sediments from the northern red sea partly laminated sediments were sampled from the brine filled anoxic shaban deep basin in the northern red sea at about 4200 cal yr bp more than two millennia of anoxic sedimentation is replaced by a sub oxic facies strongly suggesting the episodic absence of the brine at the same time stable oxygen isotopes from surface dwelling foraminifera show a sharp increase within less than 100 yr pointing to a strong positive salinity anomaly at the sea surface this major evaporation event significantly enhanced the renewal of deep water and the subsequent ventilation of the small shaban deep basin the timing and strength of the reconstructed environmental changes around 4200 cal yr bp suggest that this event is the regional expression of a major drought event which is widely observed in the neighboring regions and which strongly affected middle east agricultural civilizations

climatological evaporation seasonality in the northern red sea 1 the dynamic and thermodynamic processes that underlie the exceptionally high evaporation over the northern red sea are examined through a combination of data analysis and a simple numerical model we show that the key boundary layer dehumidifier is ageostrophic cross channel sea breezes this circulation develops semidiurnally in response to thermal gradients across the red sea s coasts because of disparate land ocean heat capacities during the summer day the thermally induced high pressure center over the red sea axis results in near surface flows from the red sea toward the neighboring deserts the strong divergence associated with these flows is maximized along the red sea axis and is accompanied by strong subsidence that suppresses boundary layer relative humidity by both reducing specific humidity and increasing temperatures because the summer nighttime reversed thermal gradients are smaller in magnitude the daytime circulation dominates over the nighttime in summer and thus dominates over the daily and seasonal means following similar reasoning we also devise a winter dehumidifier we conclude by advancing a simple means of estimating red sea evaporation under diverse paleoinsolation regimes and we show small but clear evaporation changes during the course of the holocene our estimates represent lower bounds and we plan to refine them in follow up work

organic rich sediments in brine filled shaban and kebrit deeps northern red sea the element compositions si ca and al of up to 2 1 1 ka old sediments in about 10 in long cores from the southern basin of the shaban and kebrit deeps in the northern red sea allowed a classification of major sediment types in carbonate sands and muds and siliceous oozes a feooh enriched sediment horizon and a few samples with high zn values in the kebrit core indicate a hydrothermal origin probably near the brine sea water interface with subsequent transport of hydrothermal compounds into the deep sediments high organic carbon contents up to 8 4 are positively correlated with the ba concentrations which suggests that high bioproductivity and rapid deposition c 14 dating suggests a sedimentation rate near 70 cm ka led to the formation of sapropelic sediments between 11 8 and 13 6 ka younger dryas organic petrological observations showed that the sediment organic material largely consists of 20 gm sized roundish fecal pellets intimate mixtures of organic matter and inorganic constituents and bituminite terrestrial organic matter pollens of land plants fusinite etc is very rare in the sediment cores from both deeps organic geochemical investigations of kerogens and organic extracts show that a significant hydrothermal hydrocarbon production did not occur in near surface sediments of the shaban and kebrit deeps rock eval pyrolysis of kerogens characterised the organic matter to be of type ii quality the delta c 13 values of the kerogens from the most prominent sapropel in the shaban deep indicate an enrichment of c 12 rich nutrients in the water column during postglacial sapropel formation in the younger dryas the n alkane spectra are dominated by short chain lengths between n c 15 and n c 25 prevailing n c 15 to n c 25 alkanes in low mature sediments are indicative of algal and microbial source pristane phytane ratios are generally low i to similar to 1 which suggests that anoxic conditions prevailed within the anaerobic brine filled deeps for the whole time covered by the sediments this again indicates that sapropel formation was caused by high bioproductivity in the northern red sea rather than episodic stagnation with better preservation of the organic matter long chain alkenones and sterols are the dominating compounds of the lipid fraction cholesterol contents in the sediment cores reflect phases of eukaryotes production in the water column whereas the positive correlations of dinosterol with toc and the amounts of total extract suggests that the major organic carbon source in the northern red sea during postglacial high productivity stages were dinoflagellates another important carbon source however is indicated by the occurrence of 22 29 30 trisnorhopan 21 one tnh although the formation of tnh from its precursors is not fully understood this compound probably results from microbial degradation of intact bacteriohopanepolyols bhp which can be used as indicators for bacterial abundances and phyla tnh is most likely produced at the brine sea water interface where sedimenting organic matter accumulates and if the redoxcline corresponds to the density gradient the organic matter is subjected to efficient aerobic bacterial degradation processes however during high bioproductivity stage younger dryas the redoxcline was probably higher in the water column and thus a significant tnh production at the brine sea water interface did not occur at times of sapropel formation in the northern red sea deeps c 2007 elsevier b v all rights reserved

influence of northern hemisphere climate and global sea level rise on the restricted red sea marine environment during termination i 1 we present high resolution paleoceanographic records of surface and deep water conditions within the northern red sea covering the last glacial maximum and termination i using alkenone paleothermometry stable oxygen isotopes and sediment compositional data paleoceanographic records in the restricted desert surrounded northern red sea are strongly affected by the stepwise sea level rise and appear to record and amplify well known millennial scale climate events from the north atlantic realm during the last glacial maximum lgm sea surface temperatures were about 4 c cooler than the late holocene pronounced coolings associated with heinrich event 1 2 c below the lgm level and the younger dryas imply strong atmospheric teleconnections to the north atlantic owing to the restricted exchange with the indian ocean red sea salinity is particularly sensitive to changes in global sea level paleosalinities exceeded 50 psu during the lgm a pronounced freshening of the surface waters is associated with the meltwater peaks mwp1a and mwp1b owing to an increased surface near inflow of normal saline water from the indian ocean vertical 18o gradients are also increased during these phases indicating stronger surface water stratification the combined effect of deglacial changes in sea surface temperature and salinity on water column stratification initiated the formation of two sapropel layers which were deposited under almost anoxic condition in a stagnant water body

the role of the aquifer in soil co 2 degassing in volcanic peripheral areas a case study of stromboli island italy abstract the peripheral area of stromboli island italy named scari was continuously studied between january 2009 and december 2010 data on soil co 2 flux and the partial pressure of co 2 pco 2 in equilibrium with the thermal aquifer linked to the magmatic system are presented soil co 2 fluxes range from 20 to 370 g m 2 d 1 and have been strongly affected by soil temperature variations soil co 2 flux data were filtered with respect to the soil temperature and the calculated values called residuals were considered to detect changes induced by the magmatic system the pco 2 values change in a wide range from 0 03 to 0 6 atm showing rapid variations the results of this study show that in the volcanic peripheral area the degassing process of soil co 2 is determined not only by the co 2 released directly from the magma but also by gas water interactions in the aquifer the aquifer is able to dissolve the high amount of co 2 discharged by the magmatic system moreover the residuals of co 2 flux diffused from the soil show a delay on the order of 1 month with respect to the pco 2 in equilibrium with the aquifer the soil co 2 flux is therefore not directly linked to the uprising of magmatic co 2 but instead depends on the co 2 discharged from the aquifer which buffers and modulates the volatile changes released by the magmatic system

relationships between diffuse co2 emissions and volcanic activity on the island of vulcano aeolian islands italy during the period 1984 1994 measurements of co2 flux from the ground were periodically carried out on the island of vulcano aeolian islands italy between 1984 and 1994 three high flux areas were identified at the foot of the volcanic cone la fossa either inside or very close to the main village effect of the choice of the sampling grid was evaluated a different sampling grid resulted in similar distribution patterns but with different co2 fluxes therefore the absolute estimate of the total flux from the investigated area includes a large degree of uncertainty but repeated measurements with permanent sampling sites are accurate and can detect small changes no correlation of the flux with atmospheric parameters was found at sites with high fluxes some periods characterized by high co2 fluxes were observed and a close correlation was found between the gas emissions from the ground and other geochemical and geophysical parameters such as temperature chemical composition steam and so2 flux from fumaroles seismic energy release and ground deformations the results show that major temporal variations of diffuse co2 flux are related to variations in volcanic activity

coefficients for sea surface wind stress heat flux and wind profiles as a function of wind speed and temperature surface layer coefficients for wind profiles wind stress and heat flux in typical open sea conditions are briefly reviewed businger dyer flux gradient relationships and a charnock wind stress formula fit the empirical data and are dimensionally consistent these have been solved by an iterative method and the results are presented in a tabular form suitable for climatological calculations from marine wind and temperature data

on the origins of deep and bottom waters of the indian ocean the characteristics of the deep and bottom waters of the indian ocean when illustrated on potential density anomaly surfaces indicate that the waters enter from both the atlantic and pacific oceans the paths of spreading are constrained by the complex topography and characteristics are seen to be altered by exchange with the overlying and underlying water and with the sediments especially in the northern indian ocean the weddell sea contributes to the densest waters found in the western basins and the ross sea and adelie coast to the densest waters found in the eastern basins both dense water varieties are altered by and incorporated in the less dense water above initially water carried by the circumpolar current then water from the north atlantic and finally by deep water whose characteristics are derived in the northern indian ocean contact with the sediments increases the silica content of the bottom water in the southern ocean in the northern indian ocean the sediments alter the silica of the water at the bottom and together with enhanced salinity from diffusion of saline overflows from the marginal seas above imprint unique markers to the deep water that flows back to the south at middepths the series of ridges between madagascar and australia confine the flow to a series of gyres that carry characteristics from the circumpolar current equatorward and the northern indian ocean characteristics southward within the circumpolar current low oxygen deep water from the pacific is carried across the atlantic and into the indian ocean south of africa part flows around the cyclonic weddell sea gyre and part extends across the southern ocean water from another pacific source can be seen near 2000 m extending westward from the tasman sea south of aus tralia and across the indian ocean and perhaps to the aghulas current region southeast of africa in this study we show some maps of deep and bottom water characteristics of the indian ocean which may be used in a qualitative sense to infer pathways of spreading of water below a depth of about 2000 m the indian ocean has numerous ridges and basins figure 1 that severely restrict possible pathways of deep and bottom wa ter flow in the following we will begin by looking at char acteristics at the bottom of the ocean to reveal the path ways of spreading of the densest bottom waters from basin to basin then a series of six potential density anomaly surfaces at progressively shallower depths from about 4000 m up to about 2000 m will be shown to see what character istics influence the deep waters and how pathways of flow are constrained by the bathymetry of the indian ocean the choice of the specific density levels table 1 was based primarily on various property extrema shown by the 18os atlantis ii cruise 93 colored sections that accompany warren s 1981 detailed discussion of the major features of the central indian ocean between madagascar and aus tralia the sections approximately midway between antarctica and the northern indian ocean boundaries are well positioned to show features originating from both the north and the south as well as some brought into the indi an ocean by the antarctic circumpolar current the full ocean area isopycnal maps provide essential evidence on the origins and fates of features seen in the sections and

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

deep co2 release revealed by stable isotope and diffuse degassing surveys at vulcano aeolian islands in 2015 2018 abstract the partitioning of carbon dioxide co2 released by soils at vulcano island aeolian islands italy was performed by combining the co2 flux and the carbon isotope measurements based on this method the amount of co2 of volcanic origin was quantified six times during the period 2015 2018 the data analysis allowed us to establish the correlation between co2 soil degassing and changes in the contribution of volcanic fluids carbon isotope determinations were performed in situ to enhance the coverage of data collection in space and time these data were combined with both the co2 contents in the ground gases and the soil co2 flux the amount of volcanic co2 was distinguished from that of biogenic origin by implementing a three component mixing model the results of this study indicate that the increase in co2 output in september 2018 reflects the increase in volcanic gas emissions the measurement method and analysis presented in this work are sufficiently general to be applicable to the monitoring programs of active volcanoes

the significance of diatoms in the formation of laminated sediments of the shaban deep northern red sea laminated sediments spanning the last 20 000 years though not continuously in the shaban deep a brine filled basin in the northern red sea were analyzed microscopically and with backscattered electron imagery in order to determine laminae composition with emphasis on the diatomaceous component based on this detailed study we present schematic models to propose paleoflux scenarios for laminae formation at different time slices the investigated core geob 5836 2 26 12 61 n 35 21 56 e water depth 1475 m shows light and dark alternating laminae that are easily distinguishable in the mid holocene and at the end of the deglaciation 13 15 ka period light layers are mainly composed of coccoliths terrigenous material and diatom fragments while dark layers consist almost exclusively of diatom frustules monospecific or mixed assemblages the regularity in the occurrence of coccolith diatom couplets points to an annual deposition cycle where contrasting seasons and associated plankton blooms are represented diatoms fall winter deposition coccoliths summer signal we propose that for the past 15 000 years the laminations represent two season annual varves strong dissolution of carbonate with the concomitant loss of the coccolith rich layer in sediments older than 15 ka prevents us from presenting a schematic model of annual deposition however the diatomaceous component reveals a marked switch in species composition between last glacial maximum lgm sediments dominated by chaetoceros resting spores and sediments somewhat younger 18 19 ka dominated by rhizosolenia we propose that different diatom assemblages reflect changing conditions in stratification in the northern red sea strong stratification conditions such as during two meltwater pulses at 14 5 and 11 4 ka are reflected in the sediment by rhizosolenia layers while chaetoceros dominated assemblages represent deep convection conditions

dominant northern hemisphere climate control over millennial scale glacial sea level variability abstract based on a radiocarbon and paleomagnetically dated sediment record from the northern red sea and the exceptional sensitivity of the regional changes in the oxygen isotope composition of sea water to the sea level dependent water exchange with the indian ocean we provide a new global sea level reconstruction spanning the last glacial period the sea level record has been extracted from the temperature corrected benthic stable oxygen isotopes using coral based sea level data as constraints for the sea level oxygen isotope relationship although the general features of this millennial scale sea level records have strong similarities to the rather symmetric and gradual southern hemisphere climate patterns we observe in constrast to previous findings pronounced sea level rises of up to 25 m to generally correspond with northern hemisphere warmings as recorded in greenland ice core interstadial intervals whereas sea level lowstands mostly occur during cold phases corroborated by climber 2 model results the close connection of millennial scale sea level changes to northern hemisphere temperature variations indicates a primary climatic control on the mass balance of the major northern hemisphere ice sheets and does not require a considerable antarctic contribution

volcanological and petrological evolution of vulcano island aeolian arc southern tyrrhenian sea petrological and geochemical data are reported for volcanic rocks from vulcano island the subaerial volcanism 120 ka to present built up a nw se elongated composite structure affected by two intersecting multistage calderas volcanics older than 20 ka consist mostly of high k calc alkaline hkca to shoshonitic sho mafic rocks these magmas interacted significantly with the continental crust which generated variable sr isotopic ratios 0 70412 0 70520 however a major role was also played by input of parental liquids into the magma chamber which prevented further evolution of the magmas hkca sho and potassic ks rocks formed from 20 to 8 ka display a much larger range of sio2 from shoshonites to rhyolites and higher concentrations of incompatible elements with respect to the previous stage sr isotopic ratios show small variations 0 70448 0 70486 mixing of silicic and mafic liquids and fractional crystallization processes fc were the main evolutionary processes during this stage volcanics younger than 8 ka consist of sho and leucite bearing ks mafic rocks with abundant intermediate and silicic products mafic and intermediate rocks display similar incompatible element abundances and sr isotopic ratios as the previous stage volcanics whereas higher 87sr 86sr 0 70494 0 70583 are observed in some rhyolites these products originated from a complex interplay of fc crustal assimilation and magma mixing processes the most mafic rocks show increasing incompatible element abundances rb sr rb ba mg al mg ca and a decrease in large ion lithophile to high field strength element ratios passing from older hkca sho to the younger sho ks volcanics these variations suggest a shifting of magma sources from a slightly metasomatized asthenosphere fertile peridotite to a more strongly metasomatized lithospheric mantle residual peridotite time related petrological and geochemical variations have been used to develop a model for the evolution of the vulcano plumbing system

a multidisciplinary approach to the evaluation of the mechanism that triggered the cerda landslide sicily italy abstract the present paper describes a multidisciplinary approach to the evaluation of a seismically triggered landslide that occurred in the cerda area italy on september 6 2002 about 1 h after an earthquake took place in the south tyrrhenian sea the study was focused on an analysis of the role of the seismic input in triggering the landslide in view of the evidence that no other mass movement was recorded in the adjacent areas despite geological and geomorphological spatial homogeneity the studied area is located on a slope of the western flank of the fiume imera settentrionale northern sicily which is made up of clayey arenitic rocks the slope inclines gently but is not uniform due to fluvial gravitative and rainwash processes field data dealing with global positioning system gps geology geomorphology geophysics vertical electrical sounding or ves and geochemistry soil gas fluxes and composition were acquired and analysed in order to investigate the cause effect relationships between the earthquake and the mass movement the gps survey allowed us to map the ground failures that have also been classified on the basis of their kinematical meaning i e compressive distensive or transcurrent structures the geological analysis revealed outcropping rocks and tectonic structures the geomorphologic survey highlighted the presence of preexisting landslide bodies the geophysical survey detected a buried surface located at a depth of about 100 m finally the geochemical survey showed that the gas released from the displaced mass came from a shallow depth and was not related to any active fault system the abovementioned information allowed us to interpret the landslide event as a partial reactivation of a preexisting landslide body that was triggered by the earthquake