monitoring volcano slope instability with synthetic aperture radar a review and new data from pacaya guatemala and stromboli italy volcanoes abstract volcano slope instability manifests in many forms ranging from steady state to punctuated movement or shallow erosion to deep seated spreading the interplay of gravity magmatic or hydrothermal fluids and often active tectonics on a volcanic edifice results in complex spatial and temporal variations in deformation kinematics while this makes the recognition assessment and monitoring of volcano slope instability challenging advancements in synthetic aperture radar sar technology have significantly accelerated our knowledge of instability phenomena and our ability to assess their hazards this review discusses the applications and challenges of sar imagery to various slope instabilities at volcanoes around the world sar amplitude images are powerful tools for mapping areas of geomorphological changes these snapshots can be combined using interferometric sar insar to create multi temporal deformation maps that provide unique information on the evolution of slope failures space borne insar has become an economic way to detect changes at volcanoes at very high resolution ground based insar gbinsar can produce frequent sar images on the order of seconds to minutes propelling insar from monitoring to surveillance and early warning applications however interpreting insar derived ground deformation signals related to volcano slope instability is still challenging deformation from magma rise or variations in hydrothermal systems may be inseparable from persistent deep seated flank motion similarly shallow or localized ground motion may occur in overlap with thermal contraction or subsidence of newly emplaced lava or tephra deposits if triggered to failure landslides can vary over several magnitudes from small volume rock falls that pose only a localized hazard to large volume debris avalanches capable of travelling tens of kilometers away from the source these collapses can have cascading hazards if accompanied by directed blasts or tsunamis emphasizing the need for continued advancement of our understanding of these events and their consequences to highlight the utility of sar for measuring and monitoring mass movement two case studies of stromboli italy and pacaya guatemala volcanoes are discussed in detail where recent instability events persistent volcanic activity and ground truth constraints have resulted in excellent case histories in applying sar imagery to understand these potentially hazardous slope instabilities

high resolution stalagmite climate record from the yucatan peninsula spanning the maya terminal classic period the decline of the classic maya civilization was complex and geographically variable and occurred over a 150 year interval known as the terminal classic period tcp c e 800 950 paleoclimate studies based on lake sediments from the yucatan peninsula lowlands suggested that drought prevailed during the tcp and was likely an important factor in the disintegration of the classic maya civilization the lacustrine evidence for decades of severe drought in the yucatan peninsula however does not readily explain the long 150 year socio political decline of the classic maya civilization here we present a new absolute dated highresolution stalagmite 18o record from the northwest yucatan peninsula that provides a much more detailed picture of climate variability during the last 1500 years direct calibration between stalagmite 18o and rainfall amount offers the first quantitative estimation of rainfall variability during the terminal classic period our results show that eight severe droughts lasting from 3 to 18 years occurred during major depopulation events of classic maya city states during these droughts rainfall was reduced by 52 to 36 the number and short duration of the dry intervals help explain why the tcp collapse of the mayan civilization occurred over 150 years

dissolved helium isotope ratios in ground waters a new technique based on gas water re equilibration and its application to stromboli volcanic system here a new technique for the determination of dissolved he isotope ratios in ground waters is presented this method is based on the extraction and subsequent equilibrium of dissolved gases in an added host gas phase ultra pure n2 is placed in glass flasks 250 cc containing water samples that were hermetically sealed after their collection after shaking in an ultrasonic bath for 10 min an aliquot of the separated gas phase was removed from the flask for ms analysis 3he 4he ratios are measured by using a modified double collector mass spectrometer vg 5400 tft helium and ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air standard measured by a quadrupole mass spectrometer qms vg quartz using he and ne equilibrium partitioning coefficients it is possible to calculate the amount of gas originally dissolved in the water the technique was tested on both air saturated waters asw and thermal waters from stromboli aeolian islands south italy the results of which confirmed good reproducibility 5 and accuracy 3 of the data the method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas the isotope ratios for dissolved he gave values of 4 06 4 23 ra which are significantly higher than those previously reported in the literature 3 0 3 5 and 2 9 ra and that measured at the fumarole 3 09 ra suggesting a newer and higher isotopic signature for the volcanic system the proposed method appears to be a useful tool in the determination of 3he 4he ratios in ground water systems especially when free gases are not available or are dangerous to collect

ash erupted during normal activity at stromboli aeolian islands italy raises questions on how the feeding system works ash fallout collected during 4 days of sampling at stromboli confirms that a crystal rich hp degassed magma erupts during the strombolian explosions that are characteristic of the normal activity of this volcano we identified 3 different types of juvenile ash fragments fluidal spongy and dense which formed through different mechanisms of fragmentation of the low viscosity physically heterogeneous in terms of the size and spatial distribution of bubbles shoshonitic magma a small amount less than 3 vol of volatile rich magma with low porphyricity lp erupted as highly vesicular ash fragments has been collected together with the hp magma during normal strombolian explosions laboratory experiments and the morphological textural and compositional investigations of ash fragments reveal that the lp ash is fresh and not recycled from the last paroxysm 15 march 2007 we suggest that small droplets of lp magma are dragged to the surface by the time variable but persistent supply of deep derived co2 rich gas bubbles this coupled ascent of bubbles and lp melts is transient and does not perturb the dynamics of the hp magma within the shallow reservoir this finding provides a new perspective on how the stromboli volcano works and has important implications for monitoring strategies

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

anomalous magmatic degassing prior to the 5th april 2003 paroxysm on stromboli 1 a major explosion occurred at stromboli on april 5 2003 being the most powerful event over a period of exceptional eruptive activity lasting from december to july here we describe results from a network of diffusive tubes set up on the stromboli s summit area aimed at a characterisation of plume composition so2 hcl hf prior to and after april 5 data analysis revealed anomalous sulphur degassing 2 3 days before the event when so2 hcl ratios 9 significantly higher than those typical of quiescent degassing 1 were recorded we interpret this exceptional plume signature as an evidence of s rich magmas ascending in the shallow plumbing system and propose high so2 hcl as a potential precursor of major explosions on the volcano the post april 5 phase was characterised by time decreasing so2 hcl and so2 hf plume ratios ascribed to declining magma feeding as a prelude to restoration of normal strombolian activity

eruptive activity at turrialba volcano costa rica inferences from 3he 4he in fumarole gases and chemistry of the products ejected during 2014 and 2015 a new period of eruptive activity started at turrialba volcano costa rica in 2010 after almost 150 years of quiescence this activity has been characterized by sporadic explosions whose frequency clearly increased since october 2014 this study aimed to identify the mechanisms that triggered the resumption of this eruptive activity and characterize the evolution of the phenomena over the past 2 years we integrate 3he 4he data available on fumarole gases collected in the summit area of turrialba between 1999 and 2011 with new measurements made on samples collected between september 2014 and february 2016 the results of a petrological investigation of the products that erupted between october 2014 and may 2015 are also presented we infer that the resumption of eruptive activity in 2010 was triggered by a replenishment of the plumbing system of turrialba by a new batch of magma this is supported by the increase in 3he 4he values observed since 2005 at the crater fumaroles and by comparable high values in september 2014 just before the onset of the new eruptive phase the presence of a number of fresh and juvenile glassy shards in the erupted products increased between october 2014 and may 2015 suggesting the involvement of new magma with a composition similar to that erupted in 1864 1866 we conclude that the increase in 3he 4he at the summit fumaroles since october 2015 represents strong evidence of a new phase of magma replenishment which implies that the level of activity remains high at the volcano this article is protected by copyright all rights reserved

major eruptive style changes induced by structural modifications of a shallow conduit system the 2007 2012 stromboli case stromboli is known for its mild persistent explosive activity from the vents located within the summit crater depression at the uppermost part of the sciara del fuoco sdf depression effusive activity lava flows at this volcano normally occurs every 5 15 years involving often the opening of eruptive fissures along the sdf and more rarely overflows from the summit crater between the end of the 2007 effusive eruption and december 2012 the number of lava flows inside and outside the crater depression has increased significantly reaching a total of 28 with an average of 4 8 episodes per year an open question is why this activity has become so frequent during the last 6 years and was quite rare before in this paper we describe this exceptional activity and propose an interpretation based on the structural state of the volcano changed after the 2002 2003 and even more after the 2007 flank effusive eruption we use images from the stromboli fixed cameras network as well as ground photos plume so2 and co2 fluxes released by the summit crater and continuous fumarole temperature recording to unravel the interplay between magma supply structural and morphology changes and lava flow output our results might help forecast the future behaviour and hazard at stromboli and might be applicable to other open conduit volcanoes

seismotectonics of the calabrian arc abstract relocation of intermediate and deep earthquakes of tyrrhenian sea area through joint hypocenter determination for the period 1962 1979 has allowed a more detailed definition of the geometry of this peculiar benioff zone earthquakes dip along a quasi vertical plane to 250 km depth there is a 50 dip in the 250 340 km depth range and a low dip angle to 480 km depth the structure sketched from the hypocenters is almost continuous but most energy has been released in the 230 340 km depth interval an evaluation of fault plane solutions of intermediate earthquakes in this area indicates predominance of down dip compressions in the central part of the slab at the border strike slip motion occurs independent of depth some earthquakes that occurred at intermediate depth less than 100 km along the ionian margin of calabria show predominance of reverse faulting with the p axis oriented se nw however shallow earthquakes in the calabria sicily region indicate a more complex motion with predominance of normal faulting a possible interpretation of these features according to the available geological history which involves subduction of continental lithosphere is discussed

ground based insar reveals conduit pressurization pulses at stromboli volcano at stromboli volcano southern italy only few minor precursors gas output have been identified for major strombolian explosions we use ground based interferometric synthetic aperture radar gbinsar technology to monitor the displacement rate of the summit area of stromboli we analysed the 2009 2011 period the analysis of the displacement rate has been performed by dividing the summit zone monitored by the gbinsar into three regions corresponding to the edge of the crater area 1 and 2 and to the slope of the ne crater 3 pulses of rapid expansion of sector 3 of variable duration and amplitude appear in coincidence with periods of intense activity that include lava flows and major explosions we associate this expansion with the pressurization of the magma column that is recharged by deep derived gas promoting the onset of major explosion dominated activity

new insights into magma dynamics during last two eruptions of mount etna as inferred by geochemical monitoring from 2002 to 2005 two distinct eruptive events characterize the volcanic activity at mount etna during the 2002 to 2005 period we identified signals of magma ascent preceding these eruptions by geochemical monitoring of both chemical composition and he isotope ratio of gas emissions from five locations in the peripheral area of the volcano the geochemical signals are interpreted using the models proposed by caracausi et al 2003a 2003b and allow identification of episodes of magma ascent and estimation of the pressures of degassing magma as observed for the 2001 eruption caracausi et al 2003b magma ascent probably triggered the onset of the 2002 2003 eruption and minor events of magma ascent were observed between may and december 2003 in contrast to the previous two eruptions the 2004 2005 eruption was not preceded by significant geochemical signals of volcanic unrest suggesting that this eruption was mainly triggered by the failure of the upper portion of the volcanic edifice under the magmatic hydrostatic pressure in the conduits high 3he 4he ratio revealed new volatile rich magma accumulation the 2002 2003 eruption was preceded by a much shorter period of new magma accumulation from deep levels of the feeding system few minor signals of magma migration were detected at some of the sites during the months preceding the 2004 2005 eruption suggesting that the degassed 3he depleted magma resident in the volcanic conduits was not replaced by new volatile rich magma this is in agreement with the lack of explosive activity during the 2004 2005 eruption and with petrologic observations that the parent magma probably erupted in 2000 and 2001 new geochemical signals of magma ascent from the deep reservoir have been identified since june 2005 indicating that the volcanic activity of mount etna is evolving toward new pre eruptive conditions

geochemical evidence of the renewal of volcanic activity inferred from co2 soil and so2 plume fluxes the 2007 stromboli eruption italy on 27 february 2007 a new eruption occurred on stromboli which lasted until 2 april it was characterized by effusive activity on the sciara del fuoco and by a paroxysmal event 15 march this crisis represented an opportunity for us to refine the model that had been developed previously 2002 2003 eruption and to improve our understanding of the relationship between the magmatic dynamics of the volcano and the geochemical variations in the fluids in particular the evaluation of the dynamic equilibrium between the volatiles co2 and so2 released from the magma and the corresponding fluids discharged from the summit area allowed us to evaluate the level of criticality of the volcanic activity one of the major accomplishments of this study is a 4 year database of summit soil co2 flux on the basis of which we define the thresholds low medium high for this parameter that are empirically based on the natural volcanological evolution of stromboli the so2 fluxes of the degassing plume and the co2 fluxes emitted from the soil at pizzo sopra la fossa are also presented it is noteworthy that geochemical signals of volcanic unrest have been clearly identified before during and after the effusive activity these signals were found almost simultaneously in the degassing plume so2 flux and in soil degassing co2 flux at the summit although the two degassing processes are shown to be clearly different the interpretation of the results will be useful for future volcanic surveillance at stromboli

the 2007 stromboli eruption event chronology and effusion rates using thermal infrared data accepted for publication in journal of geophysical research copyright 2009 american geophysical union further reproduction or electronic distribution is not permitted

depositional environments of overbank sedimentation in the lignite bearing grey clays member new evidence from middle miocene deposits of central poland abstract a detailed sedimentological study of polish lignite bearing successions has not previously been undertaken this contribution focuses on the lignite lithotypes and lake and crevasse splay lithofacies that together constitute the grey clays member this lithostratigraphic unit strictly refers to the middle miocene overbank fluvial environments in central poland it mostly consists of the first mid polish lignite seam mpls 1 in the tomislawice lignite opencast mine this lignite seam containing four lithotypes is interbedded by sandy and silty clayey lithofacies the lithotype associations are characteristic of the low lying mires representing fen or open water 2 m lakes in the mire area this is additional evidence of the relatively long lasting and slow sedimentation of these very fine grained clastics from suspension in standing lake water conversely the sandy lithofacies associations representing crevasse splays were deposited suddenly during overbank flooding crevasse splay deposits are typical of initial stages of avulsion and are moderately diverse both texturally and structurally exceptions here are slurry flow deposits that contain rip up clasts of paleosol aggregates these crevasse splay deposits provide the first evidence of the fluvial environments of the mid miocene mires backswamp in central poland and they split the currently exploited lignite seam mpls 1 in the study area thus identification and description of lithofacies and lithotypes and determination of their spatial distribution can contribute to a better understanding of the mire development of which the examined lignite seam arose

terminal classic drought in the northern maya lowlands inferred from multiple sediment cores in lake chichancanab mexico we present new density records from sediment cores taken along a depth transect in lake chichancanab mexico the data reveal in great detail the climatic events that comprised the terminal classic drought tcd and coincided with the demise of classic maya civilization between ca 750 and 1050 ad in shallow water cores the tcd is marked by a condensed gypsum horizon in deeper water sections it is expanded and represented by numerous interbedded gypsum and organic rich strata the tcd was not a single two century long megadrought but rather consisted of a series of dry events separated by intervening periods of relatively moister conditions we estimate the tcd occurred between ca 770 and 1100 ad and included an early phase ca 770 870 ad and late phase ca 920 1100 ad the intervening 50 year period ca 870 920 ad was relatively moister each dry phase is represented by multiple gypsum density bands interbedded with organic rich sediment that indicate alternating dry and wet conditions spectral analysis revealed significant periods around 213 50 and 27 years despite uncertainty regarding the ages of these events their pattern is robust and generally consistent with other proxy records under the same climate regime such as the marine cariaco basin off northern venezuela science 299 2003 1731

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

onset of the persistent activity at stromboli volcano italy stromboli known worldwide as the lighthouse of the mediterranean is commonly believed to have been in a state of persistent activity for the past 2000 2500 years however historical sources older than 1000 a d are not accurate enough to assess if the activity of the volcano was exactly the same as we see at present in order to attempt to identify the onset of the present eruptive regime and assess if it has been maintained with the same characteristics through time stratigraphic and radiometric studies of the recent tephra deposits were undertaken up to 4 m deep stratigraphic trenches dug at a height of approximately 500 m on the ne flank of the volcano exposed a conformable tephra pile containing charcoal fragments one of the most interesting finds was the discovery of a 7 cm thick weathered bed rich in organic matter thin palaeosol approximately 3 m below the surface the sequence underneath the palaeosol consists of decimetre thick lapilli fallout beds alternating with ash deposits bearing small charcoals with calibrated ages of between the fourth century b c and the first century a d the sequence above the palaeosol is charcoal free and consists of coarse ash deposits with discrete centimetre thick lapilli fallout beds composed of crystal poor golden pumice and subordinate crystal rich black scoriae similar to scoria pumice pairs emitted during the more energetic explosions of the present day activity the data collected indicate that between the third and seventh centuries a d after a period of quiescence the activity resumed with an eruptive style identical to the present one we conclude that the lighthouse of the mediterranean actually began its activity in a period much later than previously thought

geochemical evidence for mixing between fluids exsolved at different depths in the magmatic system of mt etna italy abstract a 4 year geochemical survey of some fumaroles at the voragine summit crater of mt etna was performed in combination with synchronous monitoring of peripheral gas emissions at the base of the volcano this was the first geochemical study at mt etna to have included the abundances of ar he and c isotopes once the effects of postmagmatic shallow processes were identified and quantitatively removed the he ar co 2 systematics of the voragine crater fumaroles and peripheral gas emissions described the same degassing path combining the carbon isotope composition with information about noble gases provided evidence that the crater fumaroles are fed from a two endmember mixture composed of a deep member coming from pressures between 200 and 400 mpa depending on time and a shallower one exsolved at 130 mpa similar mixing processes probably also occur in gases from peripheral vents the simultaneous assessment of 13 c co2 and he ar values of crater fumaroles over time has identified simple changes in the mixing proportion between the two endmembers and moreover periods during which the exsolution pressure of the deep fluid increased these periods seem to be linked to pre eruptive phases of the volcano the identified open system degassing processes are indicative of efficient bubble melt decoupling at depth whereas the mixing process requires a convective transfer of the deeply exsolved fluids toward shallower levels of magma where further vapor is exsolved in agreement with the most recent geophysical and petrological data from mt etna these observations allow inferences about a deep portion of the plumbing system 5 to 12 km b s l comprising sill like reservoirs connected by small vertical structures and a main reservoir at 2 3 km b s l that is probably fluxed by magmatic volatiles

chemical characterisation of rainwater at stromboli island italy the effect of post depositional processes abstract volcanoes emit fluids and solid particles into the atmosphere that modify the chemical composition of natural precipitation we have investigated the geochemistry of stromboli s rainfall during the period from november 2014 to march 2016 using a network of a new type of sampler specifically designed for operations on volcanic islands we found that most of the chemical modifications are due to processes occurring after the storage of rainwater in the sampling bottles these processes include dissolution of volcanogenic soluble salts encrusting volcanic ash and a variable contribution of sea spray aerosol our data showed noticeably less scatter than has previously been achieved with a different sampling system that was more open to the atmosphere this demonstrates the improved efficacy of the new sampler design the data showed that post depositional chemical alteration of rain samples dominates over processes occurring during droplet formation ad precipitation this has important implications for the calculation of fluxes of chemicals from rainfall in volcanic regions

conditions of magma storage degassing and ascent at stromboli new insights into the volcano plumbing system with inferences on the eruptive dynamics stromboli is known for its persistent degassing and rhythmic strombolian activity occasionally punctuated by paroxysmal eruptions the basaltic pumice and scoria emitted during paroxysms and strombolian activity respectively differ in their textures crystal contents and glass matrix compositions which testify to distinct conditions of crystallization degassing and magma ascent we present here an extensive dataset on major elements and volatiles co2 h2o s and cl in olivine hosted melt inclusions and embayments from pyroclasts emplaced during explosive eruptions of variable magnitude magma saturation pressures were assessed from the dissolved amounts of h2 oa nd co2 taking into account the melt composition evolution both pressures and melt inclusion compositions indicate that 1 ca basaltic melts entrapped in high mg olivines fo89 90 generate stromboli basalts through crystal fractionation and 2 the stromboli plumbing system can be imaged as a succession of magma ponding zones connected by dikes the 7 10 km interval where magmas are stored and differentiate is periodically recharged by new magma batches possibly ranging from ca basalts to basalts with a co2 rich gas phase these deep recharges promote the formation of bubbly basalt blobs which are able to intrude the shallow plumbing system 2 4 km where co2 gas fluxing enhances h2o loss crystallization and generation of crystal rich dense degassed magma chlorine partitioning into the h2o co2 bearing gas phase accounts for its efficient degassing 69 under the open system conditions of strombolian activity paroxysms however are generated through predominantly closed system ascent of basaltic magma batches from the deep storage zone in this situation crystallization is negligible and sulfur exsolution starts at 170 mpa chlorine remains dissolved in the melt until lower pressures only 16 being lost upon eruption finally we propose a continuum in explosive eruption energy from strombolian activity to large paroxysmal events ultimately controlled by variable pressurization of the deep feeding system associated with magma and gas recharges

fossil fuel energy resources of ethiopia coal deposits abstract the gravity of ethiopian energy problem has initiated studies to explore various energy resources in ethiopia one among this is the exploration for coal resources studies confirmed the presence of coal deposits in the country the coal bearing sediments are distributed in the inter trappean and pre trap volcanic geological settings and deposited in fluvio lacustrine and paludal environments in grabens and half grabens formed by a nne ssw and nnw sse fault systems most significant coal deposits are found in the inter trappean geological setting the coal and coal bearing sediments reach a maximum thickness of 4 m and 300 m respectively the best coal deposits were hosted in sandstone coal shale and mudstone coal shale facies the coal formations of ethiopia are quite unique in that they are neither comparable to the coal measures of the permo carboniferous karroo formation nor to the late devonian carboniferous of north america or northwestern europe proximate analysis and calorific value data indicated that the ethiopian coals fall under lignite to high volatile bituminous coal and genetically are classified under humic sapropelic and mixed coal vitrinite reflectance studies confirmed 0 3 0 64 ro values for the studied coals palynology studies confirmed that the ethiopian coal bearing sediments range in age from eocene to miocene a total of about 297 mt of coal reserve registered in the country the coal reserve of the country can be considered as an important alternative source of energy

cultural and climatic history of coba a lowland maya city in quintana roo mexico abstract lake coba within the archaeological site of coba provides evidence bearing on lowland maya development palynological and geochemical data record multidecadal precipitation cycles from a 8 80 m 8370 yr lake sediment sequence terminating on bedrock late classic sedimentation rates are rapid but an anthropogenically derived colluvium layer is lacking initial vegetation was medium semi deciduous and swamp forest forest clearance began 1650 b c early preclassic and maize first occurred at 850 b c middle preclassic lakeside milpas existed until a d 720 late classic and then were moved from the city center as urbanization intensified and lake coba was diked as a reservoir coba was at most briefly vacated during the classic collapse and was abandoned after a d 1240 although some habitation persisted the paleoecological record matches the archaeological history for coba but pervasive disturbance muted the climatic signal as the late classic drought is barely evident the question whether economic trees were maintained within the city is unresolved maize cultivation allowed the maya to develop a complex society and support a large population but dependence on maize was ultimately doomed by variable rainfall precipitation in extreme years was insufficient to support crops while native vegetation was not directly affected by drought that devastated maya agriculture

the 2002 2003 eruption of stromboli italy evaluation of the volcanic activity by means of continuous monitoring of soil temperature co2 flux and meteorological parameters 1 from december 2002 to july 2003 stromboli volcano was characterized by a new effusive stage of eruption after a period of extraordinary strombolian activity signals recorded in two continuous monitoring stations during the eruption which have already been presented in very recent papers evidenced anomalies in the co2 flux just before the onset of the eruption a more detailed analysis carried out on the data subset acquired during the eruption integrated by daily field observations of the scientific personnel working at the volcanological observatory in stromboli showed that co2 flux and soil temperature are strictly related to volcanic events furthermore the relative minima and maxima of the two parameters showed a strong correlation with wind speed and direction this fact was especially true at the summit station whereas at the coastal sites seasonal and meteorological effects masked the volcanic signal the analysis of the wind data particularly the relationships between wind speed and direction air and soil temperature and local circulation of atmospheric air masses revealed that during the eruption in the summit area of stromboli air movements were not only related to atmospheric circulation but were also significantly affected and in certain cases caused by volcanic activity this conclusion was reached by observing several anomalies such as the discrepancies in the wind direction between the two stations higher air temperatures at the summit site and inversion of direction for wind before and after the reopening of the conduit in a major explosion on 5 april 2003 the relationships found between volcanic activity soil temperatures co2 fluxes and wind speed and direction indicate that soil temperature measurements in an open conduit volcano such as in this case could be used to monitor the level of volcanic activity along with co2 flux furthermore the possible volcanic origin of a peculiar type of air circulation identified in the summit area of stromboli suggests that the separation between volcanic and atmospheric signals might not be obvious requiring monitoring over a wide area rather than a single location

mount etna geochemical signals of magma ascent and unusually extensive plumbing system fiveyearsofgasmonitoringfromselectedsitessuggestthatmtetna splumbingsystemismuchmoreextensivethanpreviously reported it extends at least 40 km sw from thevolcano s boundary along the ne sw regional fault whereit discharges about 200 tons day of gas containing heliumwith mantle type isotopic composition synchronousvariations of

volcanic tectonic seismicity at stromboli 2005 2016 abstract the seismicity of stromboli comprises explosion quakes volcanic tremor and volcano tectonic vt events we applied the double difference approach of waldhauser and ellsworth 2000 on 42 vt events recorded during 2005 2016 in order to improve their standard locations this approach has allowed to cluster hypocentres in two seismogenic sectors g1 and g2 respectively located inside and south of stromboli at depths of 3 5 6 and 10 12 km the seismicity belonging to g1 is located between the deep and intermediate magma storages of stromboli and seems to precede the 2007 and 2014 effusive eruptions this suggests that faulting episodes occur as a response to local stress linked to the pressurization of the magmatic system caused by magma ascent

sedimentology of the coal bearing mist mountain formation line creek southern canadian cordillera relationships to coal quality abstract a detailed sedimentological investigation of the jurassic cretaceous mist mountain formation in the southern canadian cordillera was undertaken to determine what if any sedimentological factors control coal quality and seam geometry in the line creek area the mist mountain formation is divisible into two units based on abundance and lateral continuity of facies the lower unit consists of alternating laterally extensive coal seams and thick widespread channel sandstones interspersed with crevasse splay and flood plain facies sediments the lower unit was deposited in an interdeltaic coastal plain environment protected from marine incursion by the beach ridge dune sandstones of the underlying morrissey formation the upper unit of the mist mountain formation was deposited in a distal alluvial fluvial flood plain environment and has similar facies to the lower unit but coal seams and channel sandstones are less laterally continuous and thinner than in the lower unit channel sandstones decrease in number and thickness up section and are replaced by an increasing abundance of coal seams flood plain and crevasse splay facies sediments seam geometry and ash data indicate that clastic sedimentation had only limited influence on peat coal accumulation in the mist mountain formation while the geometry of the seams reflects the proximity of under and overlying channel sandstones neither abundance nor mineralogy of the coal ash reflects changes in surrounding clastic sediments the mist mountain formation peat mires were thus not obviously influenced by coeval fluvial activity characteristics of the lower unit suggest peat mires developed only during hiatus in clastic deposition whereas upper unit coals appear to have formed in at least partially domed mires contemporaneous with clastic sedimentation the vitrinite content of the coal increases up section at the expense of semifusinite possibly reflecting an increase in the proportion of arborescent vegetation in the mire with time and a lower susceptibility to fires

geochemical monitoring of the 2002 2003 eruption at stromboli volcano italy precursory changes in the carbon and helium isotopic composition of fumarole gases and thermal waters significant changes in the helium and carbon isotopic composition of shallow thermal waters vs gas and a crater fumarolic gas have been recorded at stromboli prior and during the 2002 2003 eruption the3he 4he ratios corrected for air contamination rc ra and 13c of fumarolic gases gradually increased from may to november 2002 before the eruption onset these variations imply early degassing of a gas rich magma at depth that likely fed both the intense strombolian activity and small lava overflows recorded during that period the lava effusion of late december 2002 was shortly preceded by a marked rc ra decrease both in water and fumarolic gases comparison of he co2 and ch4 co2 ratios in dissolved gas and with rm delta 13 rm c rm co 2 values rules out the rc ra decrease due to an increasing input of radiogenic4he the rc ra decrease is attributed to the he isotope fractionation during rapid magma ascent and degassing a new uprising of 3he rich magma probably occurred in january to february 2003 when rc ra ratios displayed the highest values in dissolved gases ever measured before 4 56 rc ra the increase in he co2 and ch4 co2 ratios and decrease in 13c of dissolved co2 was recorded after the 5 april 2003 explosive paroxysm likely caused by enhanced gas water interaction inducing co2 dissolution no anomalous rc ra values were recorded in the same period when usual strombolian activity gradually resumed

a centennial scale variability of tropical north atlantic surface hydrography during the late holocene abstract sea surface temperature sst and sea surface salinity sss fluctuations in the northeastern caribbean have been reconstructed through the last 2000 yr using an artificial neural network and 18 o analyses of planktonic foraminifera a warmer period prevailed in the ne caribbean from ad 700 950 which may reflect the occurrence of stronger and or more frequent el nino events a 2 c cooling of winter ssts from ad 1400 to 1550 coincides with the occurrence of reduced solar output the sporer event episodes of lower ssss with marked minima at the onsets of the dark ages in europe ad 500 600 and little ice age ad 1400 are cyclically recurrent at intervals of 200 400 yr and coincide with drier periods in mexico this may indicate that the tropical atlantic evaporation precipitation budget and ssss are affected by a centennial scale modulation involving the freshwater export import from into the atlantic ocean coeval changes recorded in the deep north atlantic circulation indicate that low latitude sss anomalies may be advected polewards by the north atlantic current system thus affecting deep ocean convection and strength of the thermohaline circulation

calibration of xrf core scanners for quantitative geochemical logging of sediment cores theory and application abstract on line analysis of split sediment cores by xrf core scanners has become increasingly popular in the past decade because it allows nondestructive extraction of near continuous records of element intensities from sediment cores with a minimum of analytical effort a disadvantage of xrf core scanning relative to conventional geochemical analysis is the problematic conversion of core scanner output to element concentrations the main reason for this long standing problem is the poorly constrained measurement geometry attributable to inhomogeneity of the specimens e g variable water content and grain size distribution irregularities of the split core surface and in some setups spatial variations in thickness of an adhesive pore water film which forms directly below a protective foil covering the core surface we propose a log ratio calibration model for xrf core scanners derived from a combination of xrf spectrometry theory principles of compositional data analysis and empirical evidence the log ratio calibration model provides accurate and precise predictions of sediment composition element concentrations from xrf core scanner output with a limited number of parameters namely 2 d 1 where d equals the number of chemical elements whose concentrations are to be estimated the model can accommodate the inherent non linearity of the relation between relative intensities and concentrations which is apparent from the fact that it provides unbiased estimates an immediate corollary of our results is that log ratios of element intensities which are related to log ratios of element abundances by a simple linear transformation provide the most easily interpretable signals of relative changes in chemical composition consistent use of log ratios of element intensities or concentrations should minimise the risk of drawing erroneous conclusions from geochemical proxies the relative standard deviation precision of predicted element concentrations in core geob7920 is less than 2 stochastic simulations indicate that this level of precision can be attained with 40 randomly selected calibration specimens improved control over input errors and development of robust goodness of fit statistics allows xrf core scanning to be developed into a rigorous quantitative measurement technology the log ratio calibration equation derived in this study may be adapted to inter laboratory and inter instrument calibration as well

climatically sensitive eolian and hemipelagic deposition in the cariaco basin venezuela over the past 578 000 years results from al ti and k al al ti and k al ratios in bulk sediment are used to interpret wind blown and hemipelagic sources of deposition to a 578 kyr record in the cariaco basin venezuela ocean drilling program site 1002 graphical and cross spectral analyses indicate that these ratios vary extremely closely with planktonic foraminiferal 18o with both ratios being significantly higher during interglacials and lower during glacials k al indicates that during glacials the lower sea level that results in relative basin isolation increases the relative proportion of kaolinite derived from local rivers draining the relatively humid venezuelan margin al ti decreases during glacials suggesting greater proportions of eolian rutile sourced from the northern sahara due to increased wind strength and or aridity this interpretation is consistent with previous studies of the chemistry and mineralogy of saharan derived eolian matter in the caribbean and with a mass balance determining the effect of changes in eolian rutile accumulation on the bulk sedimentary al ti ratio

the 2014 effusive eruption at stromboli volcano italy inferences from soil co2 flux and 3he 4he ratio in thermal waters a new eruption started at stromboli on 6 august 2014 which had been preceded by 2 months of increased strombolian activity and several lava overflows from the craters the eruption was characterized by a lava effusion in sciara del fuoco from a fracture at 650 m above sea level that lasted until 13 17 november here we present the first geochemical observations of this eruption based on the soil co2 flux in the summit area and on 3he 4he ratios in the thermal waters near stromboli village we infer that this eruption was triggered by the gradual replenishment of the feeding system by a co2 and 3he rich magma at the end of 2013 and after june 2014 suggested by the increase in 3he 4he ratio before eruption which reached its highest value since 2007 we thus infer that this eruption was unusual and we finally speculate on the evolutionary scenario of posteruption

the 2007 eruption of stromboli volcano insights from real time measurement of the volcanic gas plume co2 so2 ratio abstract the recent eruption of stromboli in february april 2007 offered a unique chance to test our current understanding of processes driving the transition from ordinary persistent strombolian to effusive activity and the ability of instrumental geophysical and geochemical networks to interpret and predict these events here we report on the results of two years of in situ sensing of the co 2 so 2 ratio in stromboli s volcanic gas plume in the attempt to put constraints on the trigger mechanisms and dynamics of the eruption we show that large variations of the plume co 2 so 2 ratio range 0 9 26 preceded the onset of the eruption since december 2007 interrupting a period of relatively steady and low ratios time averaged ratio 4 3 lasting from at least may to november 2006 by contrasting our observations with numerical simulations of volcanic degassing at stromboli derived by use of an equilibrium saturation model we suggest that the pre eruptive increase of the ratio reflected an enhanced supply of deeply derived co 2 rich gas bubbles to the shallow plumbing system this larger than normal ascent of gas bubbles was likely sourced by a 1 3 km deep gas melt separation region probably a magma storage zone and caused faster convective overturning of magmas in the shallow conduit an increase in the explosive rate and in seismic tremor and finally the collapse of the la sciara del fuoco sector triggering the effusive phase the high co 2 so 2 ratios up to 21 observed during the effusive phase and particularly in the days and hours before a paroxysmal explosion on march 15 2007 indicate the persistence of the same gas source and suggest that de pressurization of the same 1 3 km deep magma storage zone could have been the trigger mechanism for the paroxysm itself

the 5 april 2003 vulcanian paroxysmal explosion at stromboli volcano italy from field observations and thermal data abstract the 5 april 2003 paroxysmal explosion at stromboli volcano was one of the strongest explosive events of the last century it occurred while the effusive eruption begun on 28 december 2002 and finished on 22 july 2003 was still on going and the summit craters of the volcano were obstructed in this paper we present a reconstruction of the sequence of events based on thermal and visual images collected from helicopter before during and immediately after the paroxysm one month before the blast ash emission and temperature increase at the bottom of the summit craters were observed an increasing amount of juvenile components in the emitted ash during march suggested that the magma level within the crater was rising accordingly hot degassing vents at the bottom of the summit craters were not persistent and the craters remained almost entirely obstructed by talus accumulation until the paroxysm occurred three minutes before the explosion we recorded a significant increase in temperature inside crater 1 accompanied by a thicker gas plume thirty two seconds before the blast reddish ash was emitted from crater 1 the paroxysm produced a vulcanian explosion that opened the feeder conduit obstructed for over three months the blast was accompanied by a shock wave recorded by the ingv seismic network at 07 13 37 gmt explosions with hot material started from crater 1 and after 15 s propagated to crater 3 about 100 m away the velocity of ejecta was 80 m s 1 and increased when the eruptive plumes from both craters merged together during the vulcanian phase an eruptive column rose 1 km above the top of the volcano and explosions continued mainly at crater 3 the paroxysm lasted about 9 min with bombs up to 4 m wide falling on the village of ginostra on the west flank of the island and destroying two houses this event signalled the start of the declining phase of the effusive eruption suggesting that the feeder conduit was returning to its former steady conditions with open vents and continuous mild strombolian activity

the ground based insar monitoring system at stromboli volcano linking changes in displacement rate and intensity of persistent volcanic activity stromboli volcano aeolian archipelago southern italy experienced an increase in its volcanic activity from late december 2012 to march 2013 when it produced several lava overflows major strombolian explosions crater wall collapses pyroclastic density currents and intense spatter activity an analysis of the displacement of the ne portion of the summit crater terrace and the unstable nw flank of the volcano sciara del fuoco depression has been performed with a ground based interferometric synthetic aperture radar gbinsar by dividing the monitored part of the volcano into five sectors three in the summit vents region and two in the sciara del fuoco changes in the displacement rate were observed in sectors 2 and 3 field and thermal surveys revealed the presence of an alignment of fumaroles confirming the existence of an area of structural discontinuity between sectors 2 and 3 high displacement rates in sector 2 are interpreted to indicate the increase in the magmastatic pressure within the shallow plumbing systems related to the rise of the magma level within the conduits while increased displacement rates in sector 3 are connected to the lateral expansion of the shallow plumbing system the increases and decreases in the displacement rate registered by the gbinsar system in the upper part of the volcano have been used as a proxy for changes in the pressure conditions in the shallow plumbing system of stromboli volcano and hence to forecast the occurrence of phases of higher intensity volcanic activity

caribbean sea surface temperatures two to three degrees cooler than present during the little ice age we determined the seasonal environmental conditions during the little ice age lia by interpreting isotope proxies in the coral skeleton of montastrea faveolata from the northeast caribbean the oxygen isotope composition was determined for three time intervals during the lia 1700 1705 1780 1785 1810 1815 thought to correspond to the coldest intervals the period 1984 1989 was used to represent modern calibration conditions we determined that ssts from the lia intervals are nearly 2 3 c cooler than present lia cooling in the caribbean may have resulted from regional oceanic and atmospheric circulation differences especially in winter we propose that a trough of cold air from the north atlantic may have extended farther south than present into the northern caribbean although there are indications from pacific corals that seasonality was greater during the lia this does not seem to be the case for the caribbean

geology and combustion perspectives of pakistani coals from salt range and trans indus range abstract abundant availability of low rank coals in some developing countries has a great potential for socio economic development pakistan as a developing country has taken a number of initiatives some of which are at an advanced stage thus a critical study of regional and local geology of salt range and trans indus range coals located in the kohat potwar geologic province is presented in this paper permian coal is the oldest coal which is located in the western salt range in limited quantity while palaeocene coal is the younger coal and it is mined from the hangu and patala formations the palaeocene coal is available in abundance and is mined in the eastern and central parts of the salt range and trans indus range additionally this study presents the thermo chemical analyses of the coal samples collected from thirty coal mines of salt range and trans indus range the samples were analyzed for ash composition ash fusion temperatures aft proximate analysis ultimate analysis and calorific value from two different labs i e sgs pakistan and changsha university of science and technology cust china the average aft of the samples analyzed is 1350 c which reveals that the coal is non slagging on average the coal has low slagging index medium fouling index good combustion characteristic parameters and indices the coal samples have high ash 14 50 ultra high sulfur 3 3 11 1 low moisture 3 10 high volatile matter vm 24 41 low carbon 23 57 with low to medium gross calorific value gcv 10 2 25 7 mj kg the data gathered from an extensive campaign is compared with the already published data the study has provided a knowledge on utilization of coal reserves to meet the projected energy demand in pakistan as well as in other developing countries

impact of the atlantic warm pool on united states landfalling hurricanes 1 the 2010 atlantic hurricane season was extremely active but no hurricanes made landfall in the united states raising a question of what dictated the hurricane track here we use observations from 1970 2010 also extending back to 1950 and numerical model experiments to show that the atlantic warm pool awp a large body of warm water comprised of the gulf of mexico the caribbean sea and the western tropical north atlantic plays an important role in the hurricane track an eastward expansion of the awp shifts the hurricane genesis location eastward decreasing the possibility for a hurricane to make landfall a large awp also induces barotropic stationary wave patterns that weaken the north atlantic subtropical high and produce the eastward steering flow anomalies along the eastern seaboard of the united states due to these two mechanisms hurricanes are steered toward the northeast without making landfall in the united states although the la nina event in the pacific may be associated with the increased number of atlantic hurricanes its relationship with landfalling activity has been offset in 2010 by the effect of the extremely large awp

geochemical precursors of the activity of an open conduit volcano the stromboli 2002 2003 eruptive events 1 marked increases of co2 h2 and he dissolved in thermal waters and changes in the dissolved carbon isotopic composition were observed at stromboli before the 28 december 2002 eruption and before a violent explosive paroxysm occurred on 5 april 2003 high anomalous co2 flux values were recorded at the crater rim since a week before the eruption onset the first anomalies in the thermal waters dissolved co2 amount appeared some months before the eruption when magma column rose at a very high level in the conduit high peaks of dissolved h2 and he were recorded a few days before the paroxysm carbon isotopic composition indicates a magmatic origin of the dissolved co2 whose increase together with those of h2 and he is attributed to an increasing output of deep gases likely produced by depressurization of a rising batch of a deep gas rich magma whose fragments have been emitted during the explosion

monitoring crater wall collapse at active volcanoes a study of the 12 january 2013 event at stromboli crater wall collapses are fairly frequent at active volcanoes and they are normally studied through the analysis of their deposits in this paper we present an analysis of the 12 january 2013 crater wall collapse occurring at stromboli volcano investigated by means of a monitoring network comprising visible and infrared webcams and a ground based interferometric synthetic aperture radar the network revealed the triggering mechanisms of the collapse which are comparable to the events that heralded the previous effusive eruptions in 1985 2002 2007 and 2014 the collapse occurred during a period of inflation of the summit cone and was preceded by increasing explosive activity and the enlargement of the crater weakness of the crater wall increasing magmastatic pressure within the upper conduit induced by ascending magma and mechanical erosion caused by vent opening at the base of the crater wall and by lava fingering are considered responsible for triggering the collapse on 12 january 2013 at stromboli we suggest that the combination of these factors might be a general mechanism to generate crater wall collapse at active volcanoes

tracking morphological changes and slope instability using spaceborne and ground based sar data abstract stromboli aeolian archipelago italy is an active volcano that is frequently affected by moderate to large mass wasting which has occasionally triggered tsunamis with the aim of understanding the relationship between the geomorphologic evolution and slope instability of stromboli remote sensing information from space born synthetic aperture radar sar change detection and interferometry insar and ground based insar gbinsar was compared with field observations and morphological analyses ground reflectivity and squeesar an insar algorithm for surface deformation monitoring displacement measurements from x band cosmo skymed satellites csk were analysed together with displacement measurements from a permanent sited ku band gbinsar system remote sensing results were compared with a preliminary morphological analysis of the sciara del fuoco sdf steep volcanic flank which was carried out using a high resolution digital elevation model dem finally field observations supported by infrared thermographic surveys irt allowed the interpretation and validation of remote sensing data the analysis of the entire dataset collected between january 2010 and december 2014 covers a period characterized by a low intensity of strombolian activity this period was punctuated by the occurrence of lava overflows occurring from the crater terrace evolving downslope toward sdf and flank eruptions such as the 2014 event the amplitude of the csk images collected between february 22nd 2010 and december 18th 2014 highlights that during periods characterized by low intensity strombolian activity the production of materials ejected from the crater terrace towards the sdf is generally low and erosion is the prevailing process mainly affecting the central sector of the sdf csk squeesar and gbinsar data allowed the identification of low displacements in the sdf except for high displacement rates up to 1 5 mm h that were measured following both lava delta formation after the 2007 eruption and the lava overflows of 2010 and 2011 after the emplacement of the 2014 lava field high displacements in the central and northern portions of the sdf were recorded by the gbinsar device whereas the spaceborne data were unable to detect these rapid movements a comparison between irt images and gbinsar derived displacement maps acquired during the same time interval revealed that the observed displacements along the sdf were related to the crumbling of newly emplaced 2014 lava and of its external breccia detected slope instability after the 2014 flank eruption was related to lava accumulation on the sdf and to the difference in the material underlying the 2014 lava flow i lava flows and breccia layers related to the 2002 03 and 2007 lava flow fields in the northern sdf sector and ii loose volcaniclastic deposits in the central part of the sdf this work emphasizes the importance of smart integration of spaceborne sar derived hazard information with permanent sited operational monitoring by gbinsar devices to detect areas impacted by mass wasting and volcanic activity

geochemical evaluation of observed changes in volcanic activity during the 2007 eruption at stromboli italy abstract on february 27 2007 a new eruption started at stromboli that lasted until april 2 and included a paroxysmal explosion on march 15 geochemical monitoring carried out over several years revealed some appreciable variations that preceded both the eruption onset and the explosion the carbon dioxide co 2 flux from the soil at pizzo sopra la fossa markedly increased a few days before the eruption onset and continued during lava effusion to reach its maximum value at 90 000 g m 2 d 1 a few days before the paroxysm almost contemporarily the 13 c co 2 of the sc5 fumarole located in the summit area increased markedly peaking just before the explosion 13 c co 2 1 8 following the paroxysm helium he isotopes measured in the gases dissolved in the basal thermal aquifer sharply increased almost contemporarily the automatic station of co 2 flux recorded an anomalous degassing rate also temperatures and the vertical thermal gradient which had been measured since november 2006 in the soil at pizzo sopra la fossa showed appreciable variabilities that lasted until the end of the eruption the geochemical variations indicated the degassing of a new batch of volatile rich magma that preceded and probably fed the paroxysm the anomalous 3 he 4 he ratio suggested that the ascent of a second batch of volatile rich magma toward the surface was probably responsible of the resumption of the ordinary activity a comparison with the geochemical variations observed during the 2002 2003 eruption indicated that the 2007 eruption was less energetic

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

the effects of environmental parameters on diffuse degassing at stromboli volcano insights from joint monitoring of soil co2 flux and radon activity abstract soil co 2 flux and 222 rn activity measurements may positively contribute to the geochemical monitoring of active volcanoes the influence of several environmental parameters on the gas signals has been substantially demonstrated therefore the implementation of tools capable of removing or minimising the contribution of the atmospheric effects from the acquired time series is a challenge in volcano surveillance here we present 4 years long continuous monitoring from april 2007 to september 2011 of radon activity and soil co 2 flux collected on the ne flank of stromboli volcano both gases record higher emissions during fall winter up to 2700 bq m 3 for radon and 750 g m 2 day 1 for co 2 than during spring summer seasons short time variations on 222 rn activity are modulated by changes in soil humidity rainfall and changes in soil co 2 flux that may be ascribed to variations in wind speed and direction the spectral analyses reveal diurnal and semi diurnal cycles on both gases outlining that atmospheric variations are capable to modify the gas release rate from the soil the long term soil co 2 flux shows a slow decreasing trend not visible in 222 rn activity suggesting a possible difference in the source depth of the of the gases co 2 being deeper and likely related to degassing at depth of the magma batch involved in the february april 2007 effusive eruption to minimise the effect of the environmental parameters on the 222 rn concentrations and soil co 2 fluxes two different statistical treatments were applied the multiple linear regression mlr and the principal component regression pcr these approaches allow to quantify the weight of each environmental factor on the two gas species and show a strong influence of some parameters on the gas transfer processes through soils the residual values of radon and co 2 flux i e the values obtained after correction for the environmental influence were then compared with the eruptive episodes that occurred at stromboli during the analysed time span 2007 2011 but no clear correlations emerge between soil gas release and volcanic activity this is probably due to i the distal location of the monitoring stations with respect to the active craters and to ii the fact that during the investigated period no major eruptive phenomena paroxysmal explosion flank eruption occurred comparison of mlr and pcr methods in time series analysis indicates that mlr can be more easily applied to real time data processing in monitoring of open conduit active volcanoes like stromboli where the transition to an eruptive phase may occur in relatively short times

late holocene hydroclimate of the western yucatan peninsula mexico chemical composition magnetic susceptibility and texture of sediments in a swamp from the los petenes biosphere reserve provide information about late holocene hydrological variations on the western margin of the yucatan peninsula mexico periods of lower than average amounts of k bearing clastics during 2580 2050 1100 825 and 700 160 cal a bp represent drought intervals magnetic minerals were better preserved during these arid intervals as the swamp was not perennially anoxic hydroclimate was unstable during 2580 2050 cal a bp as several storm surge events occurred within an overall arid interval the drought of 1100 825 cal a bp was contemporary with the terminal classic period and the drought of 700 160 cal a bp was characterized by the lowest erosion as well as highest abundance of authigenic carbonate comparison with other climate proxy records from the region suggests that droughts had different geographic coverage we attribute the different geographic coverage of droughts to variable strengths of polar continental air masses as well as dynamics of the caribbean low level jet and tropical cyclones that brought precipitation into different parts of the peninsula