active high resolution compressional wave attenuation tomography at newberry volcano central cascade range in this study we use the seismic data from a previous study at newberry to compute its three dimensional compressional wave attenuation structure the data consist of eight explosions recorded on an array of about 120 seismograph stations the shots are located on two concentric circles centered on the caldera with radii of 39 and 85 km attenuation is estimated using spectral ratios to compute t at each station for each shot the data are inverted using a least squares technique our results indicate that regions of inferred boiling water i e two phase pore fluid are correlated spatially with regions of high attenuation not corresponding to low velocities two regions are of particular interest one is underneath the newberry ii drill hole in the central part of the caldera where results from a flow test suggest that two phase fluid conditions existed in the bottom of the hole before the flow test the other region is beneath the west flank of the volcano which has been interpreted as an attractive geothermal prospect because of a shallow conductive anomaly our results are consistent with the suggestion made in an earlier paper by us that two phase geothermal reservoirs can be located within complex three dimensional structures by using jointly interpreted compressional wave velocity and attenuation images

magnetotelluric imaging of upper crustal convection plumes beneath the taupo volcanic zone new zealand 1 broadband mt magnetotelluric data were recorded that form an array of measurements at the south eastern margin of the tvz taupo volcanic zone in the central north island of new zealand these array data are used to investigate mechanisms by which the tvz s extraordinarily high heat flux is transported to the surface taken together with seismological data these mt data show compelling evidence that support a model of hydrothermal convection within the brittle upper 6 7 km part of the crust both 2 d and 3 d inversion models of these mt data show vertical low resistivity zones that connect surface geothermal fields to an inferred magmatic heat source that lies below the brittle ductile transition

electrical structure of newberry volcano oregon from the interpretation of magnetotelluric transient electromagnetic and schlumberger resistivity soundings the electrical structure of newberry volcano in central oregon is found to consist of four units from the surface downward the geoelectrical units are 1 very resistive young unaltered volcanic rock 2 a conductive layer of older volcanic material composed of altered tuffs 3 a thick resistive layer thought to be in part intrusive rocks and 4 a lower crustal conductor this model is similar to the regional geoelectrical structure found through the cascade range inside the caldera the conductive second layer corresponds to the steep temperature gradient and alteration minerals observed in the usgs newberry 2 test hole drill hole information on the south and north flanks of the volcano test holes ges n 1 and geo n 3 respectively indicates that outside the caldera the conductor is due to alteration minerals primarily smectite and not high temperature pore fluids on the flanks of newberry the conductor is generally deeper than inside the caldera and its deepens with distance from the summit

magma ascent beneath unzen volcano sw japan deduced from the electrical resistivity structure the resistivity structure of unzen volcano has been revealed by extensive magnetotelluric surveys since the first eruption on november 17 1990 this structure comprises a highly resistive surface layer a low resistive second layer at several hundred meters depth interpreted as a water saturated layer a resistive third layer and a low resistive fourth layer at 10 km depth possibly related to the deep magmatic activity the structure has influenced the volcanic activity of unzen this activity was characterized by a series of dramatic changes in eruption type a minor phreatic eruption on november 17 1990 phreatic eruptions after february 12 1991 preceded by several weeks of volcanic tremor phreatomagmatic eruptions after april 9 and dome effusion beginning may 19 1991 this paper presents a hypothesis in which the top of the magma column rose about 20 m day reached the base of the water saturated layer at the end of january 1991 and approached the upper boundary of this layer on april 9 thus the temporal change of eruption type and associated phenomena are systematically explained by an interaction between magma and groundwater contained in the saturated layer

laboratory measurements of electrical conductivity of hydrous and dry silicic melts under pressure an interpretation of the electrical signature of molten rocks within the earth s interior in terms of nature and temperature conditions of magma requires additional laboratory data on the electrical conductivity of silicate melts this paper describes an experimental setup and presents measurements of the electrical impedance of dry and hydrous 1 3 wt h2o metaluminous obsidians determined in an internally heated pressure vessel in the range of 50 400 mpa and 350 1325 c it is shown that the temperature and pressure dependences of electrical conductivity of both hydrous and dry obsidian can be fitted by an arrhenius law applying in the melt and the glass regions this suggests that a similar transport mechanism operates in both melt and glass the determined activation energies are 70 kj mol for the dry obsidian and 65 and 61 kj mol for the 1 and 3 wt h2o melts respectively the activation volume is 20 cm3 mol combination of tracer diffusion and electrical conductivity reveals that sodium is the dominant charge carrier in the hydrous and dry obsidians the temperature and pressure effects on conductivity are therefore interpreted in terms of activation energy and activation volume for na mobility in dry and hydrous rhyolites an increase in conductivity associated with addition of water was observed and is shown to reflect the effect of water incorporation in melts on the mobility of sodium as a prospective it is anticipated that both the mobility and content of sodium could control the electrical conductivity of most terrestrial silicate melts magma under differentiation becomes more conductive due to sodium and water enrichment associated with fractional crystallization therefore its electrical signature must reveal its nature and maturity

measurement of recent intertidal sediment transport in morecambe bay using the waterline method abstract an illustration of how sediment transport may be measured over a large dynamic intertidal area at reasonable cost and spatiotemporal resolution using the waterline method employing remote sensing and hydrodynamic modelling is presented areas and volumes of accretion and erosion were measured in the study area of morecambe bay in north west england over the period 1992 97 tidal asymmetry is considered to be the dominant agent of sediment movement in the bay with waves being of secondary importance waterlines i e land sea boundaries were extracted from 31 synthetic aperture radar images of the bay covering a substantial fraction of the tidal range heights were attached to the waterlines using water elevations from nested hydrodynamic tide surge models interpolation in space and time was carried out to produce a continuous spatiotemporal height map of the intertidal zone height maps with a spatial resolution of about 50 m and height accuracy of about 40 cm were constructed over an area of about 350 km 2 strong temporal decorrelation in the bay limited the height accuracy achievable differences between height maps for 1992 94 and 1995 97 allowed sediment volume changes to be extracted the intertidal region showed a loss of 16 1 4 5 10 6 m 3 over the period almost all the change being due to a significant decrease between mean sea level and the low water mark changes were also measured in three of the main river estuaries within the bay the leven kent and lune these included movement of the leven north east by about 2 km cutting into cartmel wharf accretion seaward of grange over sands and changes in the low water channels at the mouth of the lune these changes could be used to validate sediment transport models of the bay

robust smooth magnetotelluric transfer functions jimmy c larsen randall l mackie 2 adele man e l l a adolfo fiordelisi4 and shirley rieven2 pacific marine environmental laboratory national oceanic and atmospheric administration 7600 sand point way ne seattle wa 981 15 0070 usa wassachusetts institute of technology 42 carleton street cambridge m a 02142 usa cnr international institute for geothermal research piazza soljerino 2 pisa 56126 italy enel esplorazione mineraria via andrea pisano 120 pisa 56122 italy

remote sensing of intertidal morphological change in morecambe bay u k between 1991 and 2007 tidal flats are important examples of extensive areas of natural environment that remain relatively unaffected by man monitoring of tidal flats is required for a variety of purposes remote sensing has become an established technique for the measurement of topography over tidal flats a further requirement is to measure topographic changes in order to measure sediment budgets to date there have been few attempts to make quantitative estimates of morphological change over tidal flat areas this paper illustrates the use of remote sensing to measure quantitative and qualitative changes in the tidal flats of morecambe bay during the relatively long period 1991 2007 an understanding of the patterns of sediment transport within the bay is of considerable interest for coastal management and defence purposes tidal asymmetry is considered to be the dominant cause of morphological change in the bay with the higher currents associated with the flood tide being the main agency moulding the channel system quantitative changes were measured by comparing a digital elevation model dem of the intertidal zone formed using the waterline technique applied to satellite synthetic aperture radar sar images from 1991 1994 to a second dem constructed from airborne laser altimetry data acquired in 2005 qualitative changes were studied using additional sar images acquired since 2003 a significant movement of sediment from below mean sea level msl to above msl was detected by comparing the two digital elevation models though the proportion of this change that could be ascribed to seasonal effects was not clear between 1991 and 2004 there was a migration of the ulverston channel of the river leven north east by about 5 km followed by the development of a straighter channel to the west leaving the previous channel decoupled from the river this is thought to be due to independent tidal and fluvial forcing mechanisms acting on the channel the results demonstrate the effectiveness of remote sensing for measurement of long term morphological change in tidal flat areas an alternative use of waterlines as partial bathymetry for assimilation into a morphodynamic model of the coastal zone is also discussed

correlation of widespread holocene and pleistocene tephra layers from newberry volcano oregon usa using glass compositions and numerical analysis abstract during the last ca 500 000 years newberry volcano in oregon has produced at least 50 rhyolitic and dacitic tephras ranging from locally distributed pumice rings and cones to ignimbrites to widely dispersed plinian fallout deposits to date 13 tephra units with ages ranging from about 1525 14c years bp to 200 000 years bp have been traced to 20 sites across five western states of the usa correlations have been established by applying similarity coefficient and discriminant function analysis to major element compositions of tephra derived glasses determined by electron microprobe analysis newberry pumice correlates to four locations in oregon and idaho east lake or central pumice cone tephra correlates to two locations in oregon paulina creek ice quarry 9912d 9920c 984f 984g5 9917c and 9881c tephras correlate to ash beds at summer lake oregon paulina creek tephra also correlates to several locations in northern california and is equivalent to the olema ash bed tephra 9917c is very similar to tephras k and d at pringle falls oregon lava pass or a related tephra correlates to an unnamed tephra in the bonneville basin utah

a magnetotelluric study of mount ruapehu volcano new zealand summary mt ruapehu is an active andesite cone volcano which marks the southern termination of the kermadec volcanic arc results from 40 broad band magnetotelluric soundings have been analysed using the phase tensor this approach provides a way of determining dimensionality allowing for distortion removal and visualizing data in a 3 d situation the phase tensor analysis suggests that the shallow resistivity structure is largely 1 d in character but that the deeper structure requires a 3 d interpretation 1 d inversions show that at sites on ruapehu a shallow conductive layer lies between a high resistivity layer of a few hundred metres thickness and higher resistivity layer corresponding to basement greywacke the low resistivity layer is contiguous with the waters of the highly acidic crater lake and thus is believed to be the hydraulically controlled upper limit of a zone of acid alteration overlain by dry volcanic rock and ash to the southwest of the volcano the conductive layer merges with a surface conductor associated with tertiary sediments following initial 2 d inversions the deep resistivity structure has been derived through 3 d inversion of data from 38 sites this indicates the existence of a dyke like low resistivity zone that persists to at least 10 km depth and extends from beneath the summit of ruapehu to the northeast where it appears to connect to a poorly constrained region of high conductivity which lies outside the network of measurement sites the low resistivity dyke like feature may be identified with a volcanic feeder system which also supplies the other volcanoes of the tongariro volcanic centre and marks the conduit by which hot gases and occasionally magma reach the surface

crustal inheritance and a top down control on arc magmatism at mount st helens in a subduction zone the volcanic arc marks the location where magma generated via flux melting in the mantle wedge migrates through the crust and erupts while the location of deep magma broadly defines the arc position here we argue that crustal structures identified in geophysical data from the washington cascades magmatic arc are equally important in controlling magma ascent and defining the spatial distribution and compositional variability of erupted material as imaged by a three dimensional resistivity model a broad lower crustal mush zone containing 3 10 interconnected melt underlies this segment of the arc interpreted to episodically feed upper crustal magmatic systems and drive eruptions mount st helens is fed by melt channelled around a mid tertiary batholith also imaged in the resistivity model and supported by potential field data regionally volcanism and seismicity are almost exclusive of the batholith while at mount st helens along its margin the ascent of viscous felsic melt is enabled by deep seated metasedimentary rocks both the anomalous forearc location and composition of st helens magmas are products of this zone of localized extension along the batholith margin this work is a compelling example of inherited structural control on local stress state and magmatism crustal structures are as important as deep mantle melting in controlling magma ascent and the composition and distribution of erupted material according to 3d resistivity modelling geophysical data and the distribution of quaternary volcanism

multiple origins of obsidian pyroclasts and implications for changes in the dynamics of the 1300 b p eruption of newberry volcano usa the pyroclastic deposits of the 1300 b p eruption of newberry volcano or usa contain minor amounts of obsidian 1 6 wt the volatile h2o and co2 contents and textures of these clasts vary considerably ftir measurements of h2o in obsidian pyroclasts range from 0 1 to 1 5 wt indicating equilibration pressures 20 mpa co2 contents are low 10 ppm except in clasts that also contain xenolith powder that provided a local co2 source obsidian clasts exhibit a range of color and textural types that changed in relative proportion as the eruption progressed together these data indicate that there were multiple origins of obsidian and that the dominant source changed during the eruption early in the eruption obsidian was almost entirely black or grey microlite bearing and probably derived from dikes or wall rock fractures filled with vanguard magma or tuffisite that together with wall rocks were eroded and incorporated into the eruption column as the vent widened later in the eruption following a brief cessation of activity the proportion of obsidian to wallrock lithic clasts increased and new types of obsidian dominated types that represent remnants of a shallow conduit plug welded fallback material from within the conduit and sheared and degassed magma from near the conduit walls analysis of bubble shapes preserved within obsidian indicates that shear stresses and shear rates varied by over two orders of magnitude with maxima of 88 kpa and 10 2 3 s 1 respectively based on an assumed magma temperature of 850 c furthermore the highest shear rates and stresses and the shortest flow times 10 20 min are preserved in clasts that also contain wall rock the longest deformation times 5 and 8 h correspond to two microlite rich clasts suggesting that the higher microlite content results from slower ascent rates and or longer magma residence times at shallow levels differences between obsidian pyroclasts from the newberry eruption and those of the mono craters may relate to the nature of the conduit feeding the two events from this comparison we conclude that obsidian can provide information on time scales and mechanisms of pre fragmentation magma ascent

extracting the intertidal extent and topography of the australian coastline from a 28 year time series of landsat observations abstract the physical environment of the intertidal zone presents a number of challenges which make traditional surveying methods difficult to implement whilst the acquisition cost of airborne elevation data can be prohibitive beyond localised applications remote sensing data from earth observation satellites has been well established as a method for mapping the extent and elevation profile of the intertidal zone however the majority of these applications are local in nature and based on analysis of a limited number of individual image observations in this paper we outline an automated methodology to model the intertidal extent and topography of the australian coastline that leverages a full time series of landsat observations from 1987 to 2015 managed in the australian geoscience data cube agdc our approach reframes the analysis from time of acquisition into the tidal domain through the use of a continental scale tidal model combined with a median pixel compositing of normalised difference water index ndwi stacks to robustly estimate the tidal extent and elevation profile across the observed tidal range we demonstrate the ability of a median based compositing approach to deal effectively with data quality modelling outliers and other issues that commonly affect single scene methodologies our new framework enables us to produce a continental scale intertidal model detailing intertidal zone topography at a 25 m spatial scale we then demonstrate the potential of the modelling framework to derive digital elevation data based on tidal model attribution validating our models against in situ gps observations before discussing issues that must be addressed to move this capability to a continental scale the ability of the model to examine coastal stability is introduced in the context of the conceptual reframing of the data into the tidal domain with a view to furthering this application in future versions of the model

mapping changes in coastlines and tidal flats in developing islands using the full time series of landsat images abstract insights into the dynamics of coastlines and tidal flats at fine spatial and temporal resolutions are essential for sustainable development previous studies were generally conducted at relatively coarse temporal intervals which hardly captured detailed coastal dynamics especially in rapidly developing islands in this study we developed a new method to map the monthly changes in coastlines and tidal flats in the zhoushan archipelago during 1985 2017 using the full time series of landsat images based on the google earth engine gee platform first we built the full time series of the modified normalized difference water index mndwi second we derived temporal segments of mndwi using a binary segmentation algorithm third we classified the corresponding coastal cover types i e water tidal flats and land for each temporal segment based on the features of mndwi and regional tidal heights finally we identified the change information including conversion types and turning years and months results indicate that the proposed method can well identify turning years with an overall accuracy of 90 and map coastal cover types with overall accuracies of 89 94 in 1985 and 87 92 in 2017 significant coastline expansions and declines in tidal flats were found in the study area the areas of water and tidal flats decreased by 6 and 10 during 1985 2017 respectively while the land area increased by 18 the land reclamation was accelerated in the recent decade and mainly occurred on the medium large islands their surrounding small islands and the islands close to the mainland the proposed framework based on the gee platform is transferable to investigate coastal dynamics in other areas the derived information of changes in coastlines and tidal flats is of great use for sustainable management and ecological studies in coastal areas

a temporal waterline approach to mapping intertidal areas using x band marine radar abstract mapping the morphology of intertidal areas is a logistically challenging time consuming and expensive task due to their large expanse and difficulties associated with access a technique is presented here that uses standard marine navigational radar operating at x band frequency the method uses a series of time exposure radar images over the course of a two week tidal cycle to identify the elevation of the wetting and drying transitions at each pixel in the radar images thereby building up a morphological map of the target intertidal area this temporal waterline method is applied to a dataset acquired from hilbre island at the mouth of the dee estuary uk spanning march 2006 to january 2007 the radar gathered data with a radial range of 4 km and the resulting elevation maps describe the intertidal regions of that area the results are compared with airborne lidar data surveyed over the same area and within the radar survey time period the residual differences show good agreement across large areas of beach and sandbanks with concentrations of poor estimations around points that are shadowed from the radar or likely to suffer from pooling water this paper presents the theoretical framework of the method and demonstrates its stability and accuracy the temporal waterline radar method is aimed at providing a useful tool for the monitoring and operational management of coastlines

between the tides modelling the elevation of australia s exposed intertidal zone at continental scale abstract the intertidal zone represents a critical transition between marine and terrestrial ecosystems supporting a complex mosaic of highly productive and biologically diverse habitats however our understanding of these important coastal environments is limited by a lack of spatially consistent topographic data which can be extremely challenging and costly to obtain at continental scale satellite remote sensing represents an important resource for monitoring extensive coastal zones previous approaches to modelling the elevation of the intertidal zone using earth observation eo data have been restricted to small study regions or have relied on manual image interpretation thus limiting their ability to be applied consistently over large geographic extents in this study we present an automated open source approach to generate satellite derived elevation data for over 15 387 km2 of intertidal terrain across the entire australian coastline our approach combines global tidal modelling with a 30 year time series archive of spatially and spectrally calibrated landsat satellite data managed within the digital earth australia dea platform the resulting national intertidal digital elevation model nidem dataset provides an unprecedented three dimensional representation of australia s vast exposed intertidal zone at 25 m spatial resolution we validate our model against lidar rtk gps and multibeam bathymetry datasets finding that modelled elevations are highly accurate across sandy beach 0 41 m rmse and tidal flat environments 0 39 m rmse model performance was least accurate 2 98 m rmse within rocky shores and reefs and other complex coastal environments with extreme and variable tidal regimes we discuss key challenges associated with modelling intertidal elevation including tidal model performance and biased observations from sun synchronous satellites and suggest future directions to improve the accuracy and utility of continental scale intertidal elevation modelling our model can be applied to tidally influenced coastal environments globally addressing a key gap between the availability of sub tidal bathymetry and terrestrial elevation data

geologic evidence for a magma chamber beneath newberry volcano oregon at newberry volcano central oregon more than 0 5 m y of magmatic activity including caldera collapse and renewed caldera filling volcanism has created a structural and thermal chimney that channels magma ascent holocene rhyolitic eruptions 1 have been confined mainly within the caldera in an area 5 km in diameter 2 have been very similar in chemical composition phenocryst mineralogy and eruptive style and 3 have occurred as recently as 1300 years ago with repose periods of 2000 3000 years between eruptions holocene basaltic andesite eruptions are widespread on the flanks but are excluded from the area of rhyolitic volcanism basaltic andesite in fissures at the edge of the rhyolite area has silicic inclusions and shows mixed basalt rhyolite magma relations these geologic relations and the high geothermal gradient that characterizes the lower part of a drill hole in the caldera u s geological survey newberry 2 indicate that a rhyolitic magma chamber has existed beneath the caldera throughout the holocene its longevity probably is a result of intermittent underplating by basaltic magma

an analysis of the current deflection around dongsha islands in the northern south china sea based on the in situ data and adcp observation in fall it is found that a northeastward current at inter middle level flows on the northern south china sea nscs continental shelf this current flows almost along the isobaths and it deflects from the isobaths veering toward deep water when flowing over the dongsha islands geographic currents derived from the climatologic hydrography data woa01 and absolute dynamic topography adt data confirm the deflection of the northeastward current on nscs continent a fine resolution regional ocean model which can well reproduce the large scale circulation in the nscs is used to analyze the dynamic about the deflection the vorticity term balances shows that jebar joint effect of baroclinicity and relief drives the water column to depart from the isobaths to the east of the dongsha islands the isopycnal is almost orthogonal to the isobaths the joint effect of the topographic and the baroclinic effect supplies negative vorticity and drives the water column to deflect from the isobaths and veer to deeper water momentum analysis along the stream line shows that when the sea water flows around the dongsha islands the pressure gradient along the isobath pushes the sea water to accelerate and then the coriolis force orthogonal to the isobath increases and overcomes the corresponding pressure gradient which drives the water deflected from the isobath toward the deep sea citation wang d q wang w zhou s cai l li and b hong 2013 an analysis of the current deflection around dongsha islands in the northern south china sea j geophys res oceans 118 490 501 doi 10 1029 2012jc008429

high resolution seismic tomography of compressional wave velocity structure at newberry volcano oregon cascade range compressional wave velocity structure is determined for the upper crust beneath newberry volcano central oregon using a high resolution active source seismic tomography method newberry volcano is a bimodal shield volcano east of the axis of the cascade range it is associated both with the cascade range and with northwest migrating silicic volcanism in southeast oregon high frequency 7 hz crustal phases nominally pg and a midcrustal reflected phase travel upward through a target volume beneath newberry volcano to a dense array of 120 seismographs this arrangement is limited by station spacing to 1 to 2 km resolution in the upper 5 to 6 km of the crust beneath the volcano s summit caldera the experiment tests the hypothesis that cascade range volcanoes are underlain only by small magma chambers a small low velocity anomaly delineated about 3 km below the summit caldera supports this hypothesis for newberry volcano and is interpreted as a possible magma chamber of a few to a few tens of km3 in volume a ring shaped high velocity anomaly nearer the surface coincides with the inner mapped ring fractures of the caldera it also coincides with a circular gravity high and we interpret it as largely subsolidus silicic cone sheets the presence of this anomaly and of silicic vents along the ring fractures suggests that the fractures are a likely eruption path between the small magma chamber and the surface

detecting the intertidal morphologic change using satellite data abstract the objectives of this study were a to generate an intertidal digital elevation model dem using waterlines extracted from landsat tm and in situ ground levelling data b to quantitatively estimate morphologic change from the generated dems for the years 1991 and 2000 and c to evaluate the chenier migration in the tidal flats of gomso bay korea on extracting the waterlines we considered the tidal flat environments such as tidal conditions remnant surface water suspended sediment and exposure time ground levelling was carried out along one line in 1991 and two lines in 2000 from the extracted waterlines and ground levelling data we succeeded in generating intertidal dems with an accuracy of 10 9 cm r m s overall and 7 3 cm r m s in the lower tidal flats the morphologic changes estimated by subtracting the two dems showed an erosion rate of 9 0 cm over 9 yr that corresponds to an annual mean morphologic change budget of 309 865 m 3 yr overall the gomso tidal flats can be defined as an erosion dominant environment the changes with respect to the sedimentary facies were also evaluated as a the sandy silt flat had a sedimentation rate of 3 4 cm over 9 yr that corresponds to an annual mean budget of 52 552 m 3 yr b the silty sand flat had a sedimentation rate of 14 3 cm over 9 yr that corresponds to a mean erosion of 197 927 m 3 yr and c the sand flat had a sedimentation rate of 11 8 cm over 9 yr that corresponds to a mean change of 58 808 m 3 yr the results comply with the general rules of sedimentology we also investigated the chenier migration which is the most dynamic geomorphologic change in the tidal flats chenier is usually composed by sand and shell as a result of coastal progradation in sand and it is dominantly fed by sediments transported by long shore currents the chenier was found to have migrated about 148 m landward over 6 yr the results demonstrate that satellite remote sensing is an efficient and effective tool for a long term morphologic change estimation in tidal flats

construction of an inter tidal digital elevation model by the water line method progress in the development of a method for constructing a digital elevation model dem of an inter tidal zone using remote sensing and hydrodynamic modelling is described the method allows the construction of an inter tidal dem over large areas relatively quickly as well as frequent subsequent monitoring of the dem to detect changes and is particularly suited to sar satellite data because of the all weather day night capability of sar the resulting dem may be used for the development of improved hydrodynamic models and for studying sediment mass transport in the inter tidal zone

three dimensional resistivity structure and magma plumbing system of the kirishima volcanoes as inferred from broadband magnetotelluric data broadband magnetotelluric mt measurements were conducted in 2010 and 2011 in the vicinity of shinmoe dake volcano in the kirishima volcano group japan where sub plinian eruptions took place 3 times during 26 27 january 2011 by combining the new observations with previous mt data it is found that an anomalous phase in excess of 90 is commonly observed in the northern sector of the kirishima volcano group because the anomalous phase is not explained by 1 d or 2 d structure with isotropic resistivity media 3 d inversions were performed by applying small errors to the anomalous phase we successfully estimated a 3 d resistivity structure that explains not only the normal data but also the anomalous phase data the final model shows a vertical conductor that is located between a deep seated conductive body at a depth greater than 10 km and a shallow conductive layer by applying the findings of geophysical and petrological studies of the 2011 sub plinian eruptions we infer that the subvertical conductor represents a zone of hydrothermal aqueous fluids at temperatures over 400 c in which a magma pathway interconnected melt is partially and occasionally formed before magmatic eruptions to the north of the deep conductor earthquake swarms occurred from 1968 to 1969 suggesting that these earthquakes were caused by volcanic fluids

probing the status of felsic magma reservoirs constraints from the p t h 2 o dependences of electrical conductivity of rhyolitic melt electrical conductivity of rhyolitic melts combined with magnetotelluric data can provide important constraints for the physicochemical conditions of active felsic magma reservoirs previous experimental investigations are limited to low h2o concentration 3 wt h2o and low pressure 0 2 gpa for hydrous melts we here report new results from electrical conductivity measurements of peralkaline rhyolitic melts with 4 7 wt na2o and 0 1 7 9 wt h2o at 868 1665 k and 0 5 1 0 gpa in piston cylinder apparatuses using sweeping frequency impedance analyses logarithmic electrical conductivity is found to correlate linearly with h2o concentration and reciprocal temperature and the influence of h2o has been considerably underestimated by previous work the negative pressure effect on electrical conductivity appears to attenuate with increasing h2o concentration based on the new data we develop the following electrical conductivity model for peralkaline rhyolitic melts under conditions up to 1665 k 1 0 gpa and 8 wt h2o log 2 983 0 0732w 3528 233 8w 763 7 5w2 pt where is electrical conductivity in s m t is temperature in k w is h2o concentration in wt and p is pressure in gpa according to the nernst einstein relation this conductivity model can also be applied to metaluminous and peraluminous rhyolitic melts by scaling down according to the diffusivity and concentration of na the primary charge carrier with the new model we suggest that the highest electrical anomaly beneath the tianchi volcano corresponds to a melt fraction of 9 if the melt contains 5 wt h2o or to a melt fraction of 32 for 2 wt h2o similarly the magma reservoir beneath the taupo volcanic zone new zealand is inferred to contain a fully molten rhyolite with 7 5 wt h2o or 36 water saturated melt with 10 wt h2o

energetic topographic rossby waves in the northern south china sea abstracttopographic rossby waves trws are reported to make a significant contribution to the deep ocean current variability on the northern south china sea nscs continental slope trws with pe

maximum and minimum water contents of granitic melts generated in the crust a reevaluation and implications abstract recent results of studies aimed to determine the water solubilities and the liquidus temperatures in synthetic and natural granitic systems are used to constrain the minimum water contents of granitic melts generated in the crust as a function of pressure temperature melt composition and water activity it is concluded that melts generated in the crust at high temperature and low water activities such as a type granites contain higher water contents than previously assumed up to 20 at 800 900 c and 3 7 kbar as a consequence the melt fraction produced at a given amount of available water can be up to 20 lower the minimum water content of melts generated by partial melting of crustal protoliths especially quartzofeldspathic rocks can be predicted adequately from the liquidus curves in granitic systems this water content can be higher if the melt composition departs from a minimum or eutectic quartzofeldspathic composition melts generated from quartzofeldspathic rocks at low temperature 750 c and below are necessarily water rich 5 wt h 2 o and have approximately the same viscosity or even slightly lower viscosities than melts generated at higher temperatures viscosities in the range 10 4 3 10 5 4 pa s recent experimental data also show that the value of the positive d p d t slope of the liquidus curves for fixed water contents above 800 c is lower than predicted by previous models thus adiabatic decompression produces a higher amount of melt than previously assumed at high temperature the formation of melt by adiabatic decompression can be up to 50 higher than assumed

waterline extraction from landsat tm data in a tidal flat a case study in gomso bay korea waterline extraction is potentially one of the most effective satellite remote sensing tools for studying changes in tidal flat environment and coastlines however its application to the study of tidal flats has not been investigated in detail the waterline in a tidal flat in gomso bay korea is characterized and evaluated using 27 sets of landsat thematic mapper tm and earth observing system terra eos terra advanced spaceborne thermal emission and radiometer aster data ground truth data including grain size soil moisture content ground levelling and waterline tracking have been obtained the choice of spectral bands in terms of tidal conditions turned out to play a key role in locating the waterline while the waterlines extracted from near infrared nir short wavelength infrared swir and thermal infrared tir data are commonly reliable on the flood tide the discrepancies between different bands become large on the ebb tide the bands tir nir and swir are in that order decreasingly effective in extracting the waterline while ebb tides are in progress the effect of turbid water on nir can be reduced by a ratioing of nir and the visible band the location of the waterline is also an important factor to consider the discrepancy is largest on the middle tidal flat selection of the proper band for waterline extraction under various conditions is suggested however no single band can accommodate all aspects of the tidal flat environment a schematic model associated with the spectral reflectance of the tidal flat is proposed in which the remnant water scattered on the surface after exposure is emphasized as an additional factor

a simple waterline approach for tidelands using multi temporal satellite images a case study in the yangtze delta abstract waterline technique based on satellite remote sensing is potentially one of the most effective tools for studying changes in tidal flat environment and coastlines however multi temporal waterlines obtained from satellite images are often difficult to compare directly because fluctuant tidal conditions may produce different elevation of waterlines to overcome the difficulty this study developed a comparable waterline solution to estimate active lateral evolutions using tm satellite images at different tide conditions owing to the dynamic properties the yangtze river mouth was selected as the case example to test the suitability of the approach and totally four time slices were partitioned during 1987 2004 for investigating coastline changes the first step of this technique is to digitize waterlines with various elevations labeling in a time slice in the second step the waterlines were merged to generate dems and contour maps using the linear gridding interpolation method in the last step any interested contour line may be extracted from dems and used for comparison of tideland changes to evaluate the errors in digitizing and interpolation process quantitative checks were examined after the dems were constructed in order to monitoring the rate of coastline spread a proposed approach for estimating mean coastline spread distance between two time spans is developed in this paper to conclude this work demonstrates the importance of tm etm images to provide high frequency historical topography and morphodynamics information for coastal monitoring and evaluation

continuous monitoring of coastline dynamics in western florida with a 30 year time series of landsat imagery abstract continuous monitoring of coastline dynamics is of crucial importance to the understanding of relative contributions of various potential driving factors behind the long term coastline change while a large number of efforts have been made to extract coastline and detect coastline change with remotely sensed data the temporal frequency and spatial resolution of coastline datasets obtained are generally not fine enough to reflect the detailed process of coastline retreat and or advance particularly in coastlines with subtle variability to overcome these limitations we developed a method to continuously monitor the dynamics of a muddy coastline with subtle variability in western florida at annual and subpixel scales using time series landsat data 1984 2013 first robust indicators were used to indicate the annual average location of the dynamic coastline due to the complexity of muddy coast morphology the annual average location is represented not by the coast line but by the fractional inundated area of coastline pixels pixels where the coastline is located namely annually inundated area second the annually inundated area of coastline pixels was estimated with a model proposed in this study and the uncertainty was estimated with the monte carlo method the retrievals were validated at 10 sites with aerial imagery and the overall rmse root mean square error is 11 48 third the long term trend for the time series of annually inundated area was derived with a statistical model the results indicate that the muddy coast in western florida continues to shrink with an average rate of 0 42 0 05 km2 year during the three decades this study demonstrates the feasibility of time series landsat data in continuous monitoring of coastline dynamics

what is the cementation exponent a new interpretation in 2003 182 billion barrels of oil reserves worth about us 4 5 trillion were discovered worldwide johnson et al 2004 moreover between 1950 and 2002 the total volume of reserves discovered has run to more than 1500 billion barrels for oil and 7 5 trillion cubic feet for gas bentley 2002 more than half of these resources have already been produced and have driven the global economy for the last 50 years