variation of co2 so2 ratio in volcanic plumes of miyakejima stable degassing deduced from heliborne measurements 1 heliborne measurements of co2 so2 ratio in a volcanic plume were performed at miyakejima volcano which has degassed intensively since september 2000 the repeated measurements started in october 2000 and showed constant molar co2 so2 ratio at 0 75 0 25 despite decreased so2 emission rate from 42 kt d in late 2000 to 16 kt d in late 2001 the co2 emission rate also decreased from 21 kt d in late 2000 to 8 kt d in late 2001 the co2 content in the magma is estimated to be 1200 ppm based on the mole ratio and s content in melt inclusions 1300 ppm the estimated co2 content corresponds to a saturation pressure of 280 mpa suggesting the presence of co2 rich bubbles in the magma chamber located at 4 km the constant co2 so2 ratio over the year implies a stable magma degassing process without a change in the composition of the degassing magma

source process of very long period events accompanying long period signals at cotopaxi volcano ecuador abstract renewed seismic activity of cotopaxi ecuador began in january 2001 with the increased number of long period lp events followed by a swarm of volcano tectonic vt earthquakes in november 2001 in late june 2002 the activity of very long period vlp 2 s events accompanying lp 0 5 1 s signals began beneath the volcano the vlp waveform was characterized by an impulsive signature which was accompanied by the lp signal showing non harmonic oscillations we observed temporal changes of both the vlp and lp signals from the beginning until september 2003 the vlp signal gradually disappeared and the lp signal characterized by decaying harmonic oscillations became dominant assuming possible source geometries we applied a waveform inversion method to the observed waveforms of the largest vlp event our inversion and particle motion analyses point to volumetric changes of a sub vertical crack as the vlp source which is located at a depth of 2 3 km beneath the northeastern flank the spectral analysis of the decaying harmonic oscillations of lp events shows frequencies between 2 0 and 3 5 hz with quality factors significantly above 100 the increased vt activity and deformation data suggest an intrusion of magma beneath the volcano a release of gases with small magma particles may have repetitively occurred due to the pressurization which was caused by sustained bubble growth at the magma ceiling the released particle laden gases opened a crack above the magma system and triggered the resonance of the crack we interpret the vlp and lp events as the gas release process and the resonance of the crack respectively

conduit enlargement during the precursory plinian eruption of aira caldera japan increase in magma flux as the result of conduit enlargement is one of the key processes that triggered caldera collapse and eruption of the ito ignimbrite from aira caldera at 29 ka we examine the total volume of the pumice fall deposit vertical variations in grain size of pumice and the lithic content in the osumi pumice deposit to investigate the trigger for caldera collapse wider distribution of the later stage unit and the upward coarsening of grain size throughout the osumi pumice fall deposit indicate an increase in magma discharge toward the onset of collapse the total volume of lithic fragments in the osumi pumice fall deposit is estimated as 1 6 km3 based on the lithic content in several representative outcrops and the total volume of the osumi pumice fall deposit the lithic fragments in the osumi pumice fall deposit indicate intense mechanical erosion of the conduit during the plinian eruption prior to caldera collapse caldera collapse requires decompression of the magma chamber by withdrawal of magma effective enlargement of the conduit diameter during precursory eruptive phases is one of the important processes that subsequently allow the rapid discharge of a large volume of magma which in turn facilitates decompression of the reservoir and induces caldera collapse

geotechnical investigations at the caminada headlands beach and dune in coastal louisiana abstract the caminada headlands is a beach and dune system near port fourchon in coastal louisiana that provides natural protection for back barrier marshes against storm surges and wave overtopping due to significant shoreline erosion and regional subsidence a beach and dune restoration project was initiated in 2012 to replenish the shoreline front because of the underlying soft deltaic sediments this restoration effort was expected to cause significant increase in the applied vertical stress and thus sediment settlement to quantify the degree of settlement occurring within the compressive sediment layers and the fill extensive geotechnical investigations were conducted for design and installation of settlement plates and subsurface settlement anchors to monitor the field performance this paper presents the geological and geotechnical investigations measured material properties and corresponding empirical correlations developed from fifty one 51 laboratory consolidation tests the pre and post survey elevations of the site are also used to determine the change in vertical stress with depth at the instrumented sites the measured material properties and vertical stress profiles can be used to calibrate the numerical modeling of the sediment and fill settlements

numerical modeling of the morphodynamic response of a low lying barrier island beach and foredune system inundated during hurricane ike using xbeach and cshore abstract follet s island fi is a sediment starved barrier island located on the upper texas coast a stretch of coastline along the gulf of mexico that experiences on average four hurricanes and four tropical storms per decade during hurricane ike water levels and wave heights at fi exceeded the 100 year and 40 year return values respectively leading to significant overtopping and morphology changes of this low lying barrier island the physical processes governing the real time morphodynamic response of the beach and dune system during 96 h of hurricane impact were modeled using xbeach 2d and cshore 1d hydrodynamic boundary conditions were obtained from adcirc swan model runs validated with measured buoy and wave gauge data while lidar surveys provided pre and post storm measured topography xbeach displayed a decent model skill of 0 34 and provided numerical outputs of the entire 2d domain such as topography suspended sediment load and bed load which was very useful in visualizing erosion and deposition patterns cshore also displayed a decent model skill of 0 33 and was able to accurately predict the post storm beach slope and shoreline but was less effective at simulating the foredune morphology modeling results show that the complete morphodynamic response of fi to hurricane ike was governed by a sequence of impact regimes including swash collision overwash inundation and storm surge ebb

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

airborne measurements of volcanic gas composition during unrest at kuchinoerabujima volcano japan airborne measurements of volcanic gas composition using an unmanned aerial vehicle uav and cessna aircraft were conducted at kuchinoerabujima volcano japan between 2014 and 2016 because eruptions occurred in august 2014 may 2015 and june 2015 access to the summit crater was limited because of the risk of sudden eruption such that airborne measurements were the only viable method to measure the volcanic gas composition multi gas and alkali filter pack measurements were made on the leeward side of the crater and around the crater using the cessna and uav respectively observations using the uav could measure the dense plume and quantify the gas species of h2o co2 so2 h2s h2 hcl and hf while the observations using the cessna could measure only the diluted plume and quantify co2 so2 h2s and h2 the seven airborne observations enabled us to monitor variations in the volcanic gas composition over the observation period the so2 h2s ratio decreased from 10 to 1 9 the h2o so2 ratio h2 so2 ratio and apparent equilibrium temperatures aet estimated using the volcanic gas composition increased after the 2014 eruption the decrease in the so2 h2s ratio might be attributed to changes in the pressure of degassing magma and interactions with the hydrothermal system the airborne methods presented here highlight the utility of using light aircrafts to safely conduct volcanic gas measurements during periods of volcanic unrest when traditional ground based methods are not possible

remote determinations on fumarole outlet temperatures in an eruptive volcano direct measurement of the fumarole outlet temperature in active volcanoes is impractical therefore we used an aircraft to sample h2 in the volcanic plume ejected from sakurajima volcano to remotely estimate the highest fumarolic temperatures of the volcano based on hydrogen isotopic fractionation between h2 and magmatic h2o we successfully estimated that the d of the fumarolic h2 in september and december 2014 was 135 13 and 113 11 respectively and that the corresponding highest outlet temperatures were 1050 120 c and 1199 139 c although the temperatures were higher than those determined by using infrared remote sensing we concluded that they are more reliable estimates of the highest fumarole outlet temperatures combined with plume sampling by using aircraft remote temperature sensing based on the d of h2 in volcanic plumes can be widely applied to active volcanoes to determine the highest fumarole outlet temperatures

effects of coupled consolidation and overwash processes on a low lying headland system abstract coastal barrier islands serve as the first line of defense against storm induced hazards and coastal erosion due to sea level rise and more frequently occurring storms barrier island restoration and rehabilitation have become more important for coastal protection the current state of the practice for simulation of barrier island restoration design mostly overlooks consolidation as one of the governing processes however low lying barrier islands especially those built on loose deltaic or estuarine deposits may further lose elevation due to consolidation and become more vulnerable to erosion this study investigates the impacts of consolidation without overwash overwash without consolidation and coupled consolidation and overwash in caminada moreau headland in louisiana usa which is built on loose deltaic deposits consolidation and overwash processes were simulated by using settle3d and xbeach respectively the coupled consolidation and overwash simulations predicts twice the elevation loss predicted by the simulations that consider overwash or consolidation only indicating the critical role of consolidation in barrier island morphology based on the morphologic changes feasible restoration strategies are developed and tested through numerical experiments our analyses indicate that the simultaneous restoration of the headland and back barrier marsh increases dune volume retention and project design criteria longevity when compared to the coupled simulation without a restored marsh

kinematic features of isolated volcanic clouds revealed by video records 1 ascent processes of small volcanic clouds are analyzed using video records obtained for some eruptive events at asama and miyakejima volcanoes japan in this analysis each segment of the volcanic cloud is treated as an isolated thermal i e a spherical body ascending independently by its buoyancy our kinematic analysis reveals simple relationships among the ascent velocity radius and height of volcanic clouds the applicability of the entrainment hypothesis and the relation that was obtained from a dimensional analysis by scorer is examined for natural volcanic clouds the empirical dimensionless constants characterizing the entrainment hypothesis and the scorer s relation are more or less scattered and their mean values are about 0 36 and 0 6 respectively these empirical relations can be used to evaluate kinematic features of volcanic clouds approximately without thermodynamic consideration

rapid coastal geomorphic change in the river murray estuary of australia abstract the river murray estuary a ramsar wetland site has experienced considerable rapid coastal change during the quaternary the interplay of aeolian processes river flows tidal oscillations wave action and variations in relative sea level due to global sea level changes and land subsidence provides the energy for the ongoing dynamism often accelerated by human impacts the estuary is the terminus of the murray darling catchment which covers 1 073 million km 2 of the australian continent terminal lakes alexandrina albert and the coorong lagoon are holocene features occupying tectonically subsiding quaternary interdune areas they formed in response to eustatic sea level rise following the last glacial maximum ca 20 ka the last interglacial shoreline 125 000 yr bp parallels the modern shoreline several kilometres inland dislocation of the last interglacial shoreline demonstrates ongoing tectonic subsidence as does historical seismic activity the northern half of hindmarsh island formed during last interglacial times when it was the sink for dominant longshore transport from the southeast which pushed the river murray westward partly explaining the large bend in the river murray at goolwa the modern coastal barriers of sir richard peninsula and younghusband peninsula formed from 7000 yr ago following glacier melt and sea level rise subsequently the barriers have migrated landward sporadically exposing lagoonal sediments on the ocean beaches differential loading of the soft lagoonal sediments by advancing dunes possibly in conjunction with seismic events has deformed and elevated them to up to 10 m above present sea level apsl during the mid holocene an extensive sand flat with associated dunes formed immediately inland of the coastal barrier at least six generations of late pleistocene dune systems occur in the region for example during last glacial times the climate was drier colder and windier than at present and a system of parallel west east trending yellow red desert dunes developed around the lakes aeolian processes remain important with occasionally up to 5000 tonnes of sand being in motion along 10 km of the modern shoreline during mouth migration dunes up to 2 m high have been formed and vegetated in 12 months directly inland from the mouth and replicating the formation of older dunes on hindmarsh island elsewhere sand blown directly from the barrier system infills channels barrage construction on the beach facies of the last interglacial shoreline transformed the estuary into freshwater lakes with permanently raised water levels and reduced the tidal prism by 90 increased deposition upstream and downstream accompanied barrage construction as have accelerated lakeshore erosion and the growth and consolidation of the flood tidal delta bird island these human accelerated changes provide rapidly formed analogues of older quaternary features and aid their interpretation the shape and location of the murray mouth is constantly changing migrating over 1 6 km since the 1830s migrations of up to 6 km over the past 3000 yr have influenced sedimentation on the landward shore of the back barrier lagoonal system

two dimensional time dependent hurricane overwash and erosion modeling at santa rosa island abstract a 2dh numerical model which is capable of computing nearshore circulation and morphodynamics including dune erosion breaching and overwash is used to simulate overwash caused by hurricane ivan 2004 on a barrier island the model is forced using parametric wave and surge time series based on field data and large scale numerical model results the model predicted beach face and dune erosion reasonably well as well as the development of washover fans furthermore the model demonstrated considerable quantitative skill upwards of 66 of variance explained maximum bias 0 21 m in hindcasting the post storm shape and elevation of the subaerial barrier island when a sheet flow sediment transport limiter was applied the prediction skill ranged between 0 66 and 0 77 in a series of sensitivity tests in which several hydraulic forcing parameters were varied the sensitivity studies showed that the variations in the incident wave height and wave period affected the entire simulated island morphology while variations in the surge level gradient between the ocean and back barrier bay affected the amount of deposition on the back barrier and in the back barrier bay the model sensitivity to the sheet flow sediment transport limiter which served as a proxy for unknown factors controlling the resistance to erosion was significantly greater than the sensitivity to the hydraulic forcing parameters if no limiter was applied the simulated morphological response of the barrier island was an order of magnitude greater than the measured morphological response

predicting volcanic eruptions in recent years some major volcanic eruptions have been forecast successfully but others have claimed many lives in his perspective scarpa charts recent efforts to improve predictions of volcanic eruptions broadband seismic studies such as those of kumagai et al are a powerful tool for modeling the magma dynamics this and other techniques such as strain meters in boreholes will lead to a more quantitative approach in physical volcanology

settlement of the caminada headlands beach and dune nourishment in coastal louisiana abstractthe caminada headlands is a beach and dune system that provides natural protection for back barrier marshes against storm surges and wave overtopping due to significant shoreline erosion a

a cross shore model of barrier island migration over a compressible substrate abstract barrier islands that overlie a compressible substrate such as islands in deltaic environments or those that overlay mud or peat deposits load and consolidate the underlying subsurface through time the elevation and aerial extent of these islands are reduced making them more susceptible to future inundation and overwash sand washed over the island and onto back barrier marsh or into the bay or estuary begins the consolidation process on a previously non loaded substrate with time dependent consolidation as a function of the magnitude of the load duration of load and characteristics of the substrate the result is an increase in the overwash migration breaching and segmentation of these islands this research developed a two dimensional cross shore numerical model for evolution of a sandy barrier island that spans durations of years to decades as a function of erosion runup overwash migration and time dependent consolidation of the underlying substrate as a function of loading by the island the model was tested with field data and then applied to evaluate the effects of a compressible substrate on long term barrier island evolution results illustrate that barrier islands overlying a compressible substrate are more likely to have reduced dune elevation due to consolidation incur overall volumetric adjustment of the profile to fill in compressed regions outside the immediate footprint of the island and experience increased overwash and migration when the dune reaches a critical elevation with respect to the prevalent storm conditions

evaluation of topographic effects in remotely sensed data abstract remotely sensed data are generally analyzed assuming flat terrain as the spectral signature of the ground depends upon the orientation of the surface slope the topography has to be considered for efficient radiometric corrections in mountainous regions in this paper we present a modelization of the atmospheric downward radiance at the ground level which gives us the relative contributions of the direct solar beam and of the diffused radiation for different atmospheric turbidities and different solar incidence angles lastly we estimate the influence of the topography on these contributions to show up which effects can be neglected

subsurface cyclic magma sill expansions in the 2000 miyakejima volcano eruption possibility of two phase flow oscillation 1 step like tilt changes were observed at intervals of dozens of hours during the caldera formation stage occurred during the 2000 miyakejima volcano eruption our analysis suggests that these tilt steps were caused by the cyclic expansion of a subsurface sill like magma plumbing system trending from se to nw of the volcano in the same period a caldera gradually grew at the summit area to a very large 1 6 km in diameter and 450 m in depth the source mechanism of these tilt steps is fairly well explained by a two phase flow instability called a pressure drop oscillation this model indicates that the gas phase capacity in the upper part of the conduit acts as a pump that controls the flux of two phase magma in the sill like reservoir caldera formation as well as magma uplift and descent in the conduit may reflect temporal changes in the intervals between tilt steps which are themselves proportional to the volume of this gas capacity

rapid dune changes associated with overwash processes on the deltaic coast of south louisiana abstract the caminada moreau barrier headland of south louisiana is a low profile beach and dune coastline that is transgressing rapidly over the surfaces of the abandoned lafourche delta complex with the passage of cold fronts 10 30 times per year and hurricanes once every 4 yrs overwash events occur year round with varying degrees of frequency intensity and geomorphological modification this coastline consists of washover and dune surfaces that respond rapidly to overwash impact the fine sand stored in washover deposits is easily reworked by aeolian processes into a variety of dune forms in the shore zone that are vegetated rapidly geomorphological changes vary according to the position ground elevation and surface stability of the dunes independent factors are overwash surge elevations beach gradient and the presence of pre existing landforms for ten years detailed surveys supplemented by aerial photographs and videotape surveys have recorded these changes the analysis of these information sources provides insight into both the general evolution of this distinctive coastline and also the geomorphological interaction of dunes beaches and washover deposits in different physiographic settings

modeling discrete forest anisotropic reflectance over a sloped surface with an extended goms and sail model topographic effects on canopy reflectance play a pivotal role in the retrieval of surface biophysical variables over rugged terrain in this paper we proposed a new canopy anisotropic reflectance model for discrete forests geometric optical and mutual shadowing and scattering from arbitrarily inclined leaves model coupled with topography gosailt which considers the effects of slope aspect geotropic nature of tree growth multiple scattering and diffuse skylight gosailt simulated areal proportions of four scene components i e sunlit crown shaded crown sunlit background and shaded background were evaluated using the geometric optical model for sloping terrains gost model the canopy reflectances simulated by gosailt were validated against two reflectance data sets discrete anisotropic radiative transfer dart simulations and wide angle infrared dual model line area array scanner widas observations compared with a horizontal surface the forest canopy reflectance over a steep slope 60 is significantly distorted with absolute relative bias values of 0 048 79 60 and 0 056 12 02 for the red and near infrared nir bands respectively the gosailt simulated component areal proportions show close agreements with gost moreover gosailt simulations have high overall accuracy red band coefficient of determination r 2 0 96 root mean square error rmse 0 003 and mean absolute percentage error mape 3 91 and nir band r 2 0 78 rmse 0 019 mape 3 94 when compared with the dart simulations these extensive validations indicate good performances of gosailt in canopy reflectance simulations over sloped surfaces

hurricane gustav 2008 waves and storm surge hindcast synoptic analysis and validation in southern louisiana abstracthurricane gustav 2008 made landfall in southern louisiana on 1 september 2008 with its eye never closer than 75 km to new orleans but its waves and storm surge threatened to flood the city easterly tropical storm strength winds impacted the region east of the mississippi river for 12 15 h allowing for early surge to develop up to 3 5 m there and enter the river and the city s navigation canals during landfall winds shifted from easterly to southerly resulting in late surge development and propagation over more than 70 km of marshes on the river s west bank over more than 40 km of caernarvon marsh on the east bank and into lake pontchartrain to the north wind waves with estimated significant heights of 15 m developed in the deep gulf of mexico but were reduced in size once they reached the continental shelf the barrier islands further dissipated the waves and locally generated seas existed behind these effective breaking zones the hardening and innovative deployment of gauges since hur

an active ring fault detected at tendurek volcano by using insar 1 although ring faults are present at many ancient deeply eroded volcanoes they have been detected at only very few modern volcanic centers at the so far little studied tendurek volcano in eastern turkey we generated an ascending and a descending insar time series of its surface displacement field for the period from 2003 to 2010 we detected a large 105 km2 region that underwent subsidence at the rate of 1 cm yr during this period source modeling results show that the observed signal fits best to simulations of a near horizontal contracting sill located at around 4 5 km below the volcano summit intriguingly the residual displacement velocity field contains a steep gradient that systematically follows a system of arcuate fractures visible on the volcano s midflanks rapideye satellite optical images show that this fracture system has deflected holocene lava flows thus indicating its presence for at least several millennia we interpret the arcuate fracture system as the surface expression of an inherited ring fault that has been slowly reactivated during the detected recent subsidence these results show that volcano ring faults may not only slip rapidly during eruptive or intrusive phases but also slowly during dormant phases

an improved topography coupled kernel driven model for land surface anisotropic reflectance the semiempirical kernel driven model is commonly used for global surface reflectance characterization because of its simplicity and underlying physical meaning however the current kernel driven reflectance models assume that the terrain is flat and homogeneous and can induce significant errors in the surface reflectance estimation and subsequent parameter retrievals over rugged terrain in this study an improved topography coupled kernel driven tckd reflectance model with the correction of diffuse skylight effects was proposed based on the diffused equivalent slope model desm and rossthick litransit rtlt kernel driven model the tckd model s accuracy and effectiveness were evaluated using surface reflectance simulated by the radiosity approach and the moderate resolution imaging spectroradiometer modis data against simulated data the results show that the tckd model can accurately capture the distortion of the reflectance shape and hemispherical distribution caused by the topographic effects compared to modis data the tckd model has an overall better performance than the rtlt model across different spatial scales and land cover types when the mean slope is larger than 35 at the 500 m resolution the tckd model s near infrared nir root mean square error rmse and the regression slope of the fitting line are 0 037 and 0 752 respectively whereas those of the rtlt model are 0 049 and 0 645 neglecting the diffuse skylight in the tckd model can also lead to great bias in the reflectance retrievals when the mean slope is 31 as the ratio of diffuse skylight varies from 0 to 1 the nir rmse of the tckd model decreases from 0 012 to 0 005 whereas that increases from 0 012 to around 0 02 if the diffuse skylight effects are neglected these preliminary results demonstrate that the tckd model is capable of improving the fitting ability of the kernel driven model over rugged terrain and provides potentials for better retrieving and interpreting land surface parameters such as land surface albedo in mountainous areas

very long period seismic signals and caldera formation at miyake island japan over a period of roughly 40 days starting on 8 july 2000 a caldera structure 1 7 kilometers in diameter developed by means of gradual depression and expansion of the summit crater at miyake island japan at the same time very long period vlp seismic signals were observed once or twice a day source mechanism analyses of the vlp signals show that the moment tensor solutions are smooth step functions over a time scale of 50 seconds with dominant volumetric change components we developed a model to explain the caldera and the vlp signals in which a vertical piston of solid materials in the conduit is intermittently sucked into the magma chamber by lateral magma outflow this model offers potential for making quantitative estimations of the characteristic physical properties of magma systems

fumarole compositions and mercury emissions from the tatun volcanic field taiwan results from multi component gas analyser portable mercury spectrometer and direct sampling techniques gas emissions from tatun volcanic group northern taiwan were studied for the first time using a multi component gas analyser system multi gas in combination with giggenbach flask methods at fumaroles and mud pools at da you keng dyk and geng tze ping gzp co 2 s molar ratios observed at dyk ranged from 3 17 similar ratios were observed using a multi gas sensor box of 8 16 so 2 at gzp was low higher concentrations were observed at dyk where so 2 h 2 s ratios were close to 1 for both methods a lower co 2 h 2 s ratio was measured via giggenbach flask sampling 7 2 than was found in the plume using the gas sensor at gzp 9 2 this may reflect rapid oxidation of h 2 s as it mixes with background air gaseous elemental mercury gem levels were observed in the fumarole gases using a portable mercury spectrometer these are the first such measurements of mercury at tatun mean gem concentrations in the fumarole plumes were 20 ng m 3 with much higher concentrations observed close to the ground mean gem 130 and 290 ng m 3 at dyk and gzp respectively the gem in the fumarole plume was elevated above concentrations in industrial urban air in northern taiwan and the increase in gem observed when the instrument was lowered suggests high levels of mercury are present in the surrounding ground surface the gem co 2 10 8 and gem s 10 6 ratios observed in the fumarole gases were comparable to those observed at other low temperature fumaroles combining the hg co 2 ratio with a previous co 2 flux value for the area the annual gem flux from the tatun field is estimated as 5 50 kg year 2008 elsevier b v all rights reserved

rates of carbon dioxide plume degassing from mount etna volcano 1 we report here on the real time measurement of co2 and so2 concentrations in the near vent volcanic gas plume of mount etna acquired by the use of a field portable gas analyzer during a series of periodic field surveys on the volcano s summit during the investigated period september 2004 to september 2005 the plume co2 so2 ratio ranged from 1 9 to 10 8 with contrasting composition for northeast and voragine crater plumes scaling the above co2 so2 ratios by uv spectroscopy determined so2 emission rates we estimate co2 emission rates from the volcano in the range 0 9 67 5 kt d 1 average 9 kt d 1 about 2 kt of co2 were emitted daily on average during quiescent passive degassing whereas co2 emission rates from etna s summit were 10 40 times larger during the 2004 2005 effusive event with a cumulative co2 release of 3800 kt during the 6 months of the eruption such a syneruptive increase ascribed to the replenishment of the shallow 6 km volcanic plumbing system by co2 rich 0 25 wt more primitive magmas supports the potential of co2 output rates as key parameters for volcanic hazard assessment

magmatic dike resonances inferred from very long period seismic signals very long period vlp signals showing simple decaying harmonic oscillations with periods near 10 seconds and lasting for about 300 seconds were observed in association with an earthquake swarm that occurred beneath hachijo island japan results from the source mechanism analysis and waveform simulation based on a fluid filled crack model consistently point to the resonance of a dike filled with a basaltic magma as the source of the vlp signals thus vlp signals can be used to probe the state of the fluid and dynamic processes within a volcanic system

h2o emission rate by the volcanic plume during the 2000 2002 miyakejima volcanic activity 1 extremely intense degassing at miyakejima volcano japan was observed after the 2000 eruption the h2o emission rate was estimated using a record of infrared thermal images at 400 kton day in november 2000 by april 2002 h2o emission rate had decreased exponentially to 100 kton day the h2o emission rate varied in parallel with the so2 emission rate except for the early stage in september 2000 the ratio of h2o to so2 emission rate after november 2000 remained constant at about 10 which is consistent with the h2o so2 ratio in the magma the large rate of h2o and so2 emission requires efficient degassing at shallow depth the agreement between the gas composition of the plume and that of dissolved volatiles in melt inclusions indicates h2o discharged from the vent was mostly magmatic in origin after november 2000

tectonic control of subsidence and southward displacement of southeast louisiana with respect to stable north america 1 gps data collected between 1995 and 2006 suggest that southeast louisiana including new orleans and the larger mississippi delta are both subsiding vertically and moving southward with respect to stable north america both motions are likely related due to their common tectonic setting subsidence in the new orleans area occurs in part because it is located in the hanging wall of a large listric normal fault system that forms the northern boundary of a 7 10 km thick allochthon that is detached from stable north america southward motion of this allochthon relative to stable north america occurs at 2 2 0 6 mm yr the average subsidence rate for gps sites located on the allochthon is 5 2 0 9 mm yr relative to earth s center of mass or 7 mm yr relative to mean sea level motion of the allochthon is likely due to the gravity instability created by rapid holocene sediment deposition in the delta following continental glacial retreat and is facilitated at depth by weak salt horizons because new orleans and other communities of southeastern louisiana lie atop this active allochthon future motion of this body should be considered during rebuilding of the region following hurricanes katrina and rita

geometric and radiometric correction of tm data of mountainous forested areas methodologies to improve landsat tm thematic mapper forest classifications of alpine regions through the removal of some radiometric and geometric distortions are tested besides correcting for sensor and system induced errors geometric errors are corrected using a digital elevation model then scene related effects such as differences in illumination as well as the height dependent atmospheric influence and adjacency effects are corrected the improvement of the accuracy of a forest classification is demonstrated by comparison with ground truth data

gost a geometric optical model for sloping terrains gost is a geometric optical go model for sloping terrains developed in this study based on the four scale go model which simulates the bidirectional reflectance distribution function brdf of forest canopies on flat surfaces the four scale go model considers four scales of canopy architecture tree groups tree crowns branches and shoots in order to make this model suitable for sloping terrains the mathematical description for the projection of tree crowns on the ground has been modified to consider the fact that trees grow vertically rather than perpendicularly to sloping grounds the simulated canopy gap fraction and the area ratios of the four scene components sunlit foliage sunlit background shaded foliage and shaded background by gost compare well with those simulated by 3 d virtual canopy computer modeling techniques for a hypothetical forest gost simulations show that the differences in area ratios of the four scene components between flat and sloping terrains can reach up to 50 60 in the principal plane and about 30 in the perpendicular plane two case studies are conducted to compare modeled canopy reflectance with observations one comparison is made against landsat 5 thematic mapper tm reflectance demonstrating the ability of gost to model canopy reflectance variations with slope and aspect of the terrain another comparison is made against modis surface reflectance showing that gost with topographic consideration outperforms that without topographic consideration these comparisons confirm the ability of gost to model canopy reflectance on sloping terrains over a large range of view angles

numerical simulation of a low lying barrier island s morphological response to hurricane katrina abstract tropical cyclones that enter or form in the gulf of mexico generate storm surge and large waves that impact low lying coastlines along the gulf coast the chandeleur islands located 161 km east of new orleans louisiana have endured numerous hurricanes that have passed nearby hurricane katrina landfall near waveland ms 29 aug 2005 caused dramatic changes to the island elevation and shape in this paper the predictability of hurricane induced barrier island erosion and accretion is evaluated using a coupled hydrodynamic and morphodynamic model known as xbeach pre and post storm island topography was surveyed with an airborne lidar system numerical simulations utilized realistic surge and wave conditions determined from larger scale hydrodynamic models simulations included model sensitivity tests with varying grid size and temporal resolutions model predicted bathymetry topography and post storm survey data both showed similar patterns of island erosion such as increased dissection by channels however the model under predicted the magnitude of erosion potential causes for under prediction include 1 errors in the initial conditions the initial bathymetry topography was measured three years prior to katrina 2 errors in the forcing conditions a result of our omission of storms prior to katrina and or errors in katrina storm conditions and or 3 physical processes that were omitted from the model e g inclusion of sediment variations and bio physical processes

inundation of a barrier island chandeleur islands louisiana usa during a hurricane observed water level gradients and modeled seaward sand transport large geomorphic changes to barrier islands may occur during inundation when storm surge exceeds island elevation inundation occurs episodically and under energetic conditions that make quantitative observations difficult we measured water levels on both sides of a barrier island in the northern chandeleur islands during inundation by hurricane isaac wind patterns caused the water levels to slope from the bay side to the ocean side for much of the storm modeled geomorphic changes during the storm were very sensitive to the cross island slopes imposed by water level boundary conditions simulations with equal or landward sloping water levels produced the characteristic barrier island storm response of overwash deposits or displaced berms with smoother final topography simulations using the observed seaward sloping water levels produced cross barrier channels and deposits of sand on the ocean side consistent with poststorm observations this sensitivity indicates that accurate water level boundary conditions must be applied on both sides of a barrier to correctly represent the geomorphic response to inundation events more broadly the consequence of seaward transport is that it alters the relationship between storm intensity and volume of landward transport sand transported to the ocean side may move downdrift or aid poststorm recovery by moving onto the beach face or closing recent breaches but it does not contribute to island transgression or appear as an overwash deposit in the back barrier stratigraphic record the high vulnerability of the chandeleur islands allowed us to observe processes that are infrequent but may be important at other barrier islands

geomorphic response type model for barrier coastlines a regional perspective based on quantitative documentation of historical changes in shoreline position between 1847 and 1991 eight geomorphic response types were established for classifying megascale changes along barrier coastlines 1 lateral movement 2 advance 3 dynamic equilibrium 4 retreat 5 in place narrowing 6 landward rollover 7 breakup and 8 rotational instability long term decades to centuries monitoring of shoreline position over a spatial scale of 10 to 100 km provides a scientific basis for documenting process response relationships that shape regional coastal morphodynamics although megascale shoreline change studies often are lacking this type of information is critical for developing realistic research and management strategies regarding form process relationships in coastal depositional systems the spatial distribution of geomorphic response types is delineated along the barrier coastlines of louisiana mississippi and southern georgia northern florida at megascale the rate of relative sea level rise along these barrier coastlines appears to be one of the major factors controlling the occurrence of geomorphic response types however sediment supply exerts significant influence on shoreline response as well

morphodynamic modeling of the response of two barrier islands to atlantic hurricane forcing abstract the accurate prediction of a barrier island response to storms is challenging because of the complex interaction between hydro and morphodynamic processes that changes at different stages during an event assessment of the predictive skill is further complicated because of uncertainty in the hydraulic forcing initial conditions and the parameterization of processes to evaluate these uncertainties we investigated the morphological change that occurred during two atlantic hurricane events on two barrier islands at matanzas florida and fire island new york with differing topographies and forcing conditions we used the morphodynamic model xbeach with hydrodynamic forcing extracted from a regional coupled d flow fm swan model the xbeach model was initialized with a spatially varying roughness map derived from a land cover classification map generated with supervised conditional random field classification the model was supplemented with a dynamic roughness module recognizing that under extreme conditions vegetation can be washed away or buried by sediment for the fire island case the modeled spatial extent of roughness reduction as a proxy for vegetation removal during the storm was accurate for both the fire island and matanzas cases the model predicted erosion and deposition volumes and dune crest lowering well the occurrence of breach formation was also predicted by the model but the exact location of these breaches did not match observations variations of 10 in boundary conditions surge wave direction significant wave height and bay water levels produced regime shifts in modeled barrier island response these results not only stress the critical role of boundary conditions in morphodynamic model skill but also show the limitations of single deterministic model runs in forecasting impact

topographic effects on bidirectional and hemispherical reflectances calculated with a geometric optical canopy model the effects of topography on both the bidirectional reflectance distribution function brdf and the hemispherical reflectance surface albedo of a forested scene are investigated with the li strahler geometric optical model the li strahler geometric optical model treats a vegetation canopy as an assemblage of partially illuminated tree crowns of spheroidal shape and through geometric optics and boolean set theory models the proportion of sunlit or shadowed canopy and background as functions of view angle illumination angle and crown geometry the model has been modified to accommodate a sloping surface in its computation of bidirectional and hemispherical reflectance when the brdf of a flat vegetated surface is compared to the brdf of a sloping surface that is similarly vegetated the interaction of the illumination angle and the slope distort the shape of the brdf a hemispherical integration of this distorted brdf provides an albedo for the sloping surface

a dike intrusion model in and around miyakejima niijima and kozushima in 2000 from june 26 2000 an earthquake swarm started in miyakejima about 50 km south off honshu central japan eruptions of miyakejima and five large earthquakes with magnitudes 6 0 and above occurred for the following 2 months together with a large number of smaller earthquakes over 100 000 in this study we focused on spatio temporal crustal deformation observed at gps stations in this area in order to explain the seismicity and the crustal deformation we considered a dike intrusion model placed between miyakejima and kozushima then we attempted to obtain spatio temporal distributions the amount of the dike intrusion deflation beneath miyakejima and fault slips of the seven large events by geodetic data inversion for this purpose we divided the time series of gps data from june 12 to august 27 into 10 periods which are related to significant events in order to find location depth strike and dip of the dike plane and a depth of deflation beneath miyakejima we used the monte carlo method and tested 10 000 models for each period as a result we estimated that the total amount of the dike intrusion and the deflation beneath miyakejima reached about 1 1 10 9 and 5 4 10 8 m 3 respectively the maximum amount of the dike intrusion and the deflation beneath miyakejima reached over 3 5 10 8 m 3 during the period from july 20 to july 28 2000 and over 1 7 10 8 m 3 during the period from june 15 to june 28 2000 respectively temporal change of the amount of the dike intrusion corresponds well to that of the deflation beneath miyakejima until the middle of july however since large amount of the dike intrusion from july 20 to 28 did not correspond to that of the deflation beneath miyakejima we deduced that the magma source changed from miyakejima to kozushima and the magma might come from sub crustal magma pockets from the middle of july if we assume the open crack associated with the dike intrusion and the deflation beneath miyakejima are filled with magma with a density of 2500 kg m 3 the mass would be about 2 75 10 9 and 1 35 10 9 tons respectively we deduced that at least 1 4 10 9 tons of magma came from sub crustal magma pockets d 2002 elsevier science b v all rights reserved

the effect of small topographic variations on reflectance the influence of topography on the bidirectional reflectance factors brfs of vegetation canopies is commonly neglected when retrieving canopy parameters by inversion of reflectance models however the nonlinear dependence of vegetation brfs on slope magnitude and orientation means that topography cannot necessarily be assumed to have an insignificant effect even when slopes are small the study presented here shows that at a sun zenith angle of 60 spl deg the reflectance of a set of terrain elements may differ from that of horizontal terrain by more than 10 at forward scattering directions for slopes of 10 spl deg or less the errors may also be strongly correlated to observation conditions which raises questions about using least squares minimization schemes to find the best fit between measured and modeled reflectance data

the definition of remotely sensed reflectance quantities suitable for rugged terrain abstract the anisotropic scattering behavior of land surface is characterized by its bidirectional reflectance distribution function brdf however a physically consistent brdf definition is still lacking for heterogeneous and rugged terrain that accounts for approximately 24 of earth s land surface in this study we revisited current brdf definitions and updated them for rugged terrain with few dependent parameters illumination and viewing geometries terrain shadows effective areas of illumination and observation and anisotropic reflectance properties of subpixel scale slopes furthermore the bidirectional reflectance factor brf hemispherical directional reflectance factor hdrf directional hemispheric reflectance dhr and bi hemispherical reflectance bhr were proposed within the current physical framework of reflectance quantities these reflectance quantities have been adopted by the 3 d discrete anisotropic radiative transfer dart model to provide the simulations of remote sensing images to highlight the importance of a proper usage of such reflectance terms we used dart simulations to present the topographic effects on these reflectance quantities finally the other issues with respect to surface brdf brf such as spatial scale of rugged terrain characterization of anisotropic reflectance of micro scale surfaces derivative reflectance quantities topographic parameters wavelength dependence and reciprocity and future perspective were discussed

caldera collapse during the 2000 eruption of miyakejima volcano japan a collapsed caldera 1 6 km in diameter and 450 m in depth was formed at the summit of miyakejima volcano during the 2000 eruption the collapsed caldera appeared on 8 july with a minor phreatic eruption 12 days after seismic activity and magma intrusion occurred northwest of the volcano growth of the caldera took from 8 july to the middle of august with seismic swarms associated with the continuous intrusion of magma northwest of the volcano the growth rate of the caldera was about 1 4 107 m3 day and the final volume of the collapsed caldera was about 6 108 m3 major phreatomagmatic eruptions produced a total of about 1 6 1010 kg 1 1 107 m3 of volcanic ash after caldera growth the caldera structure and the nature of the eruptive materials of the first collapse on 8 july suggest that the surface subsidence was caused by the upward migration of a steam filled cavity with stoping of the roof rock above the magma reservoir the diameter of the stoping column was estimated to be 600 700 m from circumferential faults that developed in the caldera floor and the collapse of the caldera wall enlarged the diameter of the caldera to 1 6 km the total volume of the caldera and the horizontal diameter of the stoping column gave a subsidence of the caldera floor of 1 6 2 1 km

variation of h2o co2 and co2 so2 ratios of volcanic gases discharged by continuous degassing of mount etna volcano italy 1 we applied the multi gas technique to measure compositions of the volcanic plumes continuously discharged from summit craters of voragine northeast and bocca nuova at mount etna in an attempt to estimate compositions of the source volcanic gases the estimated co2 so2 and h2o co2 ratios of the volcanic gases show a large variation ranging from 0 6 to 30 and from 1 to 18 respectively this variability overlaps with the compositional range of dissolved volatiles in melt inclusions and their coexisting bubbles in a magma chamber and can be caused by the low pressure degassing of a magma with variable bubble content ranging from 0 3 to 15 wt the variable bubble content in the magma is likely a result of supply of deep derived co2 rich gas phase to the chamber and subsequent bubble magma differentiation by bubble ascent in the magma chamber in contrast the variation of volcanic gas composition can also be caused by changes of degassing pressure gas magma separation pressure ranging from 0 to 100 mpa as a result of changes in the depth of the top of the convecting magma in volcanic conduits both mechanisms can cause similar compositional variations however the two mechanisms will result in contrasting correlations between the so2 emission rates and the gas compositions that can be examined by parallel observations of the emission rates and compositions in the future

fluid immiscibility in volcanic environments volatile components enter the atmosphere oceans and other surface waters through pre syn and post eruptive volcanic processes that involve a variety of fluids aluminosilicate poor fluids include aqueous or carbonic to sulfide sulfate chloride fluoride carbonate and phosphate rich compositions in volcanic environments but other more complex combinations of these constituents may be involved giggenbach 1977 roedder 1984 1992 lowenstern 1995 other rare gases and dissolved constituents e g h2 n2 he ar h3bo3 hg ch4 and other hydrocarbon compounds metals and metalloids are also present but in general they are not sufficiently concentrated to form their own phases or control bulk fluid composition and volcanic processes as a result of their diverse compositions volcanic fluids ranging from vapor to liquid exhibit widely different densities and show strong distinctions in heat capacity dielectric behavior viscosity and other chemical and physical characteristics geiger et al 2006a the density of a saline liquid in the system nacl h2o at 50 mpa and 800 c for example is more than 7 times that of the coexisting aqueous vapor e g 0 2 gm cm3 henley and mcnabb 1978 multiple fluids move mix and or unmix in magma chambers and volcanic conduits in the root zone of fumaroles and in the convective hydrothermal systems that are ubiquitous to volcanic environments hydrothermal systems are typically centered on magmatic intrusions and may include crater lakes at the top of eruptive conduits hydrothermal processes involving two or more fluid phases operate through a variety of geologically relevant shallow crustal pressure temperature composition conditions volcanic fluids occur at supersolidus to subsolidus conditions meaning that the dense aluminosilicate melt that is common to volcanism may or may not be present this chapter addresses the evidence for and occurrence of two or more low density aluminosilicate poor fluids

hydrogen isotopes in volcanic plumes tracers for remote temperature sensing of fumaroles abstract in high temperature volcanic fumaroles 400 c the isotopic composition of molecular hydrogen h2 reaches equilibrium with that of the fumarolic h2o in this study we used this hydrogen isotope exchange equilibrium of fumarolic h2 as a tracer for the remote temperature at volcanic fumaroles in this remote sensing we deduced the hydrogen isotopic composition d value of fumarolic h2 from those in the volcanic plume to ascertain that we can estimate the d value of fumarolic h2 from those in a volcanic plume we estimated the values in three fumaroles with outlet temperatures of 630 c tarumae 203 c kuju and 107 c e san for this we measured the concentration and d value of h2 in each volcanic plume along with those determined directly at each fumarole the average and maximum mixing ratios of fumarolic h2 within a plume s total h2 were 97 and 99 at tarumae 89 and 96 at kuju and 97 and 99 at e san we found a linear relationship between the depletion in the d values of h2 with the reciprocal of h2 concentration furthermore the estimated end member d value for each h2 enriched component 260 30 vs vsmow in tarumae 509 23 in kuju and 437 14 in e san coincided well with those observed at each fumarole 247 0 0 6 in tarumae 527 7 10 1 in kuju and 432 1 2 5 in e san moreover the calculated isotopic temperatures at the fumaroles agreed to within 20 c with the observed outlet temperature at tarumae and kuju we deduced that the d value of the fumarolic h2 was quenched within the volcanic plume this enabled us to remotely estimate these in the fumarole and thus the outlet temperature of fumaroles at least for those having the outlet temperatures more than 400 c by applying this methodology to the volcanic plume emitted from the crater 1 of mt naka dake the volcano aso where direct measurement on fumaroles was impractical we estimated that the d value of the fumarolic h2 to be 172 16 and the outlet temperature to be 868 97 c the remote temperature sensing using hydrogen isotopes developed in this study is widely applicable to many volcanic systems

an evaluation of subsidence rates and sea level variability in the northern gulf of mexico 1 while subsidence is widely recognized as a driver of geomorphic change in the northern gulf of mexico gom there is considerable disagreement over the rates of subsidence and the interpreted variability in these rates which leads to controversies over the impacts of subsidence on surface land area change here we present a new method to calculate subsidence rates from the tide gauge record that is based on an understanding of the meteorological drivers of inter annual sea level change in grand isle la and galveston tx we explicitly show that temporal patterns of subsidence are closely linked to subsurface fluid withdrawal and coastal land loss and suggest changes in withdrawal rates can both increase and decrease rates of subsidence and wetland loss our results also imply that the volume of sediment needed to rebuild gom wetlands may currently fall within the low end of some restoration scenarios

transgressive depositional systems of the mississippi delta plain a model for barrier shoreline and shelf sand development abstract depositional sequences generated in the mississippi river delta plain consist of a regressive and a transgressive component the transgressive component has been considerably less studied but accounts for the majority of the surface area on the lower mississippi river delta plain and up to 50 percent of the total sequence thickness in shallow water deltas the development and preservation of transgressive depositional systems in abandoned delta complexes follows the process of transgressive submergence in which the horizontal component of reworking occurs during shoreface retreat combined with a vertical component of submergence acting to preserve the sequence the evolution of transgressive depositional systems in each of the abandoned holocene mississippi river delta complex s can be summarized in a three stage model beginning with stage 1 an erosional headland and flanking barriers in this stage regressive sand deposits contained within abandoned deltaic headlands are reworked by the eroding shoreface and dispersed longshore into contiguous flanking barriers enclosing restricted interdistributary bays submergence of the delta plain during relative sea level rise generates an intradeltaic lagoon separating the former stage 1 sand body from the shoreline forming stage 2 a transgressive barrier island arc the landward migrating barrier island arc is unable to keep pace with relative sea level rise and the retreating mainland shoreline resulting in submergence and the formation of stage 3 an inner shelf shoal following submergence the former barrier island arc sand body continues to be reworked into a marine sand body on the inner continental shelf during stage 3 this sequence of coastal evolution provides direct evidence of barrier island formation with each stage producing a distinctive stratigraphic signature the current sea level rise models of shoreface retreat and in place drowning developed for the u s atlantic continental shelf do not adequately explain either the morphology or the stratigraphy of transgressive mississippi river delta sand bodies current models of mississippi deltaic stratigraphy emphasize the deep water artificially maintained balize delta which differs considerably from the shallow water shelf phase delta complexes that are the primary depositional constituents of he holocene mississippi river delta plain

extending a turbid medium brdf model to allow sloping terrain with a vertical plant stand this paper extends the turbid medium approach used for modeling bidirectional reflectance from horizontal plant canopies to sloping terrain with a vertically oriented plant stand previous treatments have accounted for terrain slope by simple adaptation to an inclined plane of models for horizontal surfaces however such treatments implicitly assume that plants grow perpendicularly to the surface despite the fact that plant stems continue to grow vertically on slopes the authors investigate the differences between their new vertical growth model and the more usual perpendicular to the surface growth model in terms of the effect on canopy albedo and bidirectional reflectance factors although the effect of leaf angle distribution on the albedo is different for both the vertical growth and perpendicular growth models it appears to be a much smaller effect than that due to terrain slope for the bidirectional reflectance factors brfs the magnitude and sign of the differences between the two models varies with the direction of observation the slope and the leaf angle distribution and can exceed 10 for a planophile canopy a comparison between modeled and measured data shows that model predictions under the vertical growth assumption are consistent with measurements whereas the assumption of perpendicular growth can lead to large errors