the sea level fingerprint of west antarctic collapse recent projections of sea level rise after a future collapse of thewest antarctic ice sheet for example the fourth intergovernmental panel on climate change assessment report assume that meltwater will spread uniformly that is eustatically across the oceans once marine based sectors of the west antarctic are filled a largely neglected 1977 study predicted that peak values would be 20 higher than the eustatic in the north pacific and 5 to 10 higher along the u s coastline we show with use of a state of the art theory that the sea level rise in excess of the eustatic value will be two to three times higher than previously predicted for u s coastal sites

the lamongan volcanic field east java indonesia physical volcanology historic activity and hazards abstract the lamongan volcanic field lvf in east java indonesia consists of up to 61 basaltic cinder or spatter cones a minimum of 29 prehistoric maars and a central compound complex comprising three main vents including the historically active lamongan volcano the field lies on the sunda volcanic arc and abuts onto the currently active tengger caldera semeru complex to the west between 1799 and 1898 lamongan was persistently active and discharged up to 15 lava flows of basaltic to basaltic andesite composition which is probably more than what was erupted by any other indonesian volcano in that period several seismic crises have been recorded in the lvf since lamongan s last eruption there are no existing records of cinder cone or maar forming eruptions in the area despite the possible hazards posed by future activity in the lvf the history and structure of the field have been subject to little scrutiny this contribution presents the results of a detailed morphometric and volumetric investigation of prehistoric vents and historic lava flows in the lvf using field data historic records satellite imagery and modelling of erupted volumes a typical lvf maar is characterised as a crater with a diameter of 450 m generated by an eruption with a model ejecta volume of 0 016 km 3 dense rock equivalent dre and a model juvenile component volume of 0 0096 km 3 dre diameter depth ratios of some maars display a morphological freshness comparable to recently formed phreatomagmatic eruption craters elsewhere the median lvf cinder spatter cone has a basal diameter of 600 m a height of 75 m a volume of 0 009 km 3 and a model total erupted volume of 0 014 km 3 variation in cone basal diameter to height ratios indicates that the age of some prehistoric cones may not exceed a few centuries and morphological classification identifies the youngest prehistoric vents on the northern flanks of the central edifice historic activity from vents on the western flanks of lamongan produced at least 0 05 km 3 of basaltic to basaltic andesite lava resurfacing rates at lamongan in the 19th century imply an age of 900 2100 years for the surface of the volcano the steady state eruptive rate from 1843 1898 is evaluated as 0 025 m 3 s 1 which is low in comparison to estimates from many presently active systems using eruptive rate and volume data the age of the lvf is estimated as between 13 and 40 ka placing it among the youngest dated indonesian volcanoes complex regional tectonics in conjunction with magmatic pressure have probably been the major influences on the distribution of volcanism in the lvf the occurrence of maar forming eruptions may have been controlled by a porous substrate possibly a deposit from the holocene iyang argapura complex to the east volcanic hazards from future eruptions in the lvf include base surges ash flows ashfall and ejected blocks associated with phreatomagmatic activity and ashfall and ejecta from magmatic eruptions

niche construction within riparian corridors part i exploring biogeomorphic feedback windows of three pioneer riparian species allier river france abstract within riparian corridors biotic abiotic feedback mechanisms occur between woody vegetation strongly influenced by hydrogeomorphic constraints e g sediment transport and deposition shear stress hydrological variability fluvial landforms and morphodynamics which in turn are modulated by the established vegetation during field investigations in spring 2015 we studied 16 alluvial bars e g point and lateral bars within the dynamic riparian corridor of the allier river france to assess the aptitude of three pioneer riparian salicaceae species populus nigra l salix purpurea l and salix alba l to establish and act as ecosystem engineers by trapping sediment and constructing fluvial landforms our aim is to empirically identify the preferential establishment area ea i e the local areas where species become established and the preferential biogeomorphic feedback window bfw i e where and to what extent the species and geomorphology interact of these three species on alluvial bars within a 20 km long river reach our results show that the ea and bfw of all three species vary significantly along the longitudinal profile i e upstream downstream exposure on the alluvial bars as well as transversally i e the main hydrological connectivity gradient from the river channel toward the floodplain in the present day context of the allier river p nigra is the most abundant species appearing to act as the main engineer species affecting landform dynamics at the bar scale s purpurea is established and acts as an ecosystem engineer at locations on alluvial bars that are most exposed to hydrosedimentary flow dynamics while s alba is established on the bar tail close to secondary channels and affects the geomorphology in mixed patches along with p nigra our study highlights the role of functional trait diversity of riparian engineer species in controlling the extent of fluvial landform construction along geomorphic gradients within riparian corridors exposed to frequent hydrogeomorphic disturbances

wet surge deposits at la fossa di vulcano depositional and eruptive mechanisms abstract wet surge deposits of different volcanic cycles of the recent fossa activity at vulcano have been measured on a bed by bed basis with data recorded to millimeter detail the wet surge layers are varicoloured with variable thickness with the most recurrent thickness being about 1 cm the beds consist of fine ash without internal structures textural features include a accretionary lapilli of maximum size of 0 5 cm dispersed thoroughout the layer or forming continuous layers of submillimeter size b vesiculated layers which represent 10 to 65 of the total deposit vesicles have different shapes and smooth walls varying in volume from 1 to 15 20 c soft sediment types of bedding deformation such as gravity flowage ripples load cast and slumps the slope angle has not influenced either the concentration and size of the accretionary lapilli or the shape size and distribution of vesicles only the thickness of the layers decreases with distance from the vent sem investigations show features indicating the hydromagmatic origin of the deposits and stressing the role of the fluid phase noteworthy is the presence of vesiculated grains produced by magmatic exsolution which show chilling effects on the internal walls of the broken bubbles grain size analyses reveal that the layers are not graded and most of the samples have a median size finer than 50 m the grain size distributions are frequently polymodal suggesting several closely timed explosions as all the beds exhibit the same textures grain size and particle morphology a single mechanism can explain their deposition the depositional unit formed at the base of the cloud through the lateral expansion on the ground of a sticky muddy medium consisting of ash and fluid in general each layer lost its plasticity before the deposition of the next layer the deposition occurred in a nearly continuous sequence without periods of rest long enough to permit erosional discontinuity the eruptions are hydromagmatic and occur where magma at least partially fragmented comes into effective contact with subsurface water the process follows a model suggested by wohletz 1983b 1986 developing in more than one fragmentation event in the turbulent surge cloud both severe hydration and alteration of glassy grains and the formation of accretionary lapilli occur

coseismic and postseismic deformation of the 2011 tohoku oki earthquake constrained by grace gravimetry 1 spaceborne gravimetry data from the gravity recovery and climate experiment grace are processed using spatio spectral slepian localization analysis enabling the high resolution detection of permanent gravity change associated with both coseismic and postseismic deformation resulting from the great 11 march 2011 mw 9 0 tohoku oki earthquake the grace observations are then used in a geophysical inversion to estimate a new slip model containing both coseismic slip and after slip the grace estimated moment for the total slip up to the end of july 2011 is estimated as 4 59 0 49 1022 n m equivalent to a composite mw of 9 07 0 65 if the moment for the tohoku oki main shock is assumed to be 3 8 1022 n m the contribution from the after slip is estimated to be 3 0 1021 12 8 1021 n m in good agreement with a postseismic slip model inverted from gps data we conclude that grace data provide an independent constraint to quantify co and post seismic deformation for the tohoku oki event

miocene phreatomagmatic volcanism at tihany pannonian basin hungary abstract a late miocene 7 56 ma maar volcanic complex tihany maar volcanic complex tmvc is preserved in the pannonian basin and is part of the bakony balaton highland volcanic field base surge and fallout deposits were formed around maars by phreatomagmatic explosions caused by interactions between water saturated sediments and alkali basalt magma carrying peridotite lherzolite xenoliths as well as pyroxene and olivine megacrysts subsequently nested maars functioned as a sediment trap where deposition built up gilbert type delta sequences at the onset of eruption magma began to interact with a moderate amount of groundwater in the water saturated sand as eruption continued phreatomagmatic blasts excavated downward into limestones providing access to abundant karst water and deeper to sandstones and schist both providing large amount of fracture filling water at the surface this wet eruption led to the emplacement of massive tuff breccias by fall surge mudflow and gravity flow deposition the nature of the tmvc maar eruptions and their deposits appears to depend on the hydrological condition of the karst and or fracture filling aquifer which varies seasonally with rainfall and spring runoff the west and east maar volcanoes of tmvc are interpreted to represent low water input from the karst and or fracture filling aquifer summer vent whereas the east maar is interpreted to have formed when abundant karst and or fracture filling water was available spring vent

tectonically controlled vent migration during maar diatreme formation an example from a miocene half graben basin in se korea abstract understanding the roles of external controls such as hydrology and tectonics is crucial for interpreting the evolution of a phreatomagmatic volcano and its subsurface structure called the diatreme the yangpori diatreme in a miocene terrestrial half graben basin of korea provides an opportunity to assess the roles of synvolcanic fault movement in forming a maar diatreme volcano the exposed part of the diatreme fill consists of two offset stacked sequences with contrasting lithofacies characteristics a lower sequence early diatreme fill of locally stratified or bedded basaltic lapilli tuff and tuff in the northeastern part and an upper sequence later diatreme fill of dacite clast rich and disorganized tuff breccia in the southwestern part the boundary between these sequences is abrupt suggesting eruption of the volcano in two distinct phases the first phase of eruption was driven by phreatomagmatic explosions mainly within the basin fill some of the diatreme fill was deposited in a local pond by debris flows and suspension settling of fines whereas the rest by fallout from eruption plumes and jets the second phase of eruption was driven by phreatomagmatic explosions at a fracture aquifer within the basement accompanying sudden lowering of the explosion locus the later diatreme fill therefore contains abundant basement derived dacite clasts its deposition was accomplished by en masse fallout of volcanic debris from dense collapsing columns a number of faults and shear fractures were generated within and in the vicinity of the diatreme together with penecontemporaneous basaltic intrusions structural and geochemical analyses show that many of these structures are genetically related with the formation of the diatreme the early diatreme fill was also tilted toward the southwest suggesting southwestward shift of the locus of explosion and diatreme excavation the explosion locus of the yangpori volcano is therefore interpreted to have migrated both vertically and laterally the abrupt lithofacies boundary between the early and later diatreme fills and the proximity of the diatreme to the basin margin suggests that the migration was caused by an abrupt tectonic activity near the basin margin most probably the feeder dike was dislocated by movement along the basin margin fault which created abundant fractures deep within the basement that redirected ascending magma and opened a new hydraulically active zone in the basement synvolcanic faulting is therefore interpreted to have played a crucial role in forming the offset stacked architecture of the yangpori diatreme sequences the faulting is also inferred to have influenced significantly the morphology and internal facies architecture of unpreserved ejecta rimbeds

variations of the earth s figure axis from satellite laser ranging and grace 1 satellite laser ranging slr data were used to determine the variations in the earth s principal figure axis represented by the degree 2 and order 1 geopotential coefficients c21 and s21 significant variations at the annual and chandler wobble frequencies appear in the slr time series when the rotational deformation or pole tides i e the solid earth and ocean pole tides were not modeled the contribution of the ocean pole tide is estimated to be only 8 of the total annual variations in the normalized coefficients based on the analysis of slr data the amplitude of the nontidal annual variation of is only 30 of from the slr time series the estimates of the annual variation in from slr the gravity recovery and climate experiment grace and polar motion excitation function are in a good agreement the nature of the linear trend for the earth s figure axis determined by these techniques during the last several years is in general agreement but does not agree as well with results predicted from current glacial isostatic adjustment gia models the fluid love number for the earth is estimated to be 0 9 based on the position of the mean figure axis from the grace gravity model ggm03s and the mean pole defined by the iers 2003 conventions the estimate of from grace and slr provides an improved constraint on the relative rotation of the core the results presented here indicate a possible tilt of the inner core figure axis of 2 and 3 arc sec displacement for the figure axis of the entire core

time variable ice loss in asian high mountains from satellite gravimetry abstract substantial amount of glacial ice is considered to be melting in the asian high mountains gravimetry by grace satellite during 2003 2009 suggests the average ice loss rate in this region of 47 12 gigaton gt yr 1 equivalent to 0 13 0 04 mm yr 1 sea level rise this is twice as fast as the average rate over 40 years before the studied period and agrees with the global tendency of accelerating glacial loss such ice loss rate varies both in time and space mass loss in himalaya is slightly decelerating while those in northwestern glaciers show clear acceleration uncertainty still remains in the groundwater decline in northern india and proportion of almost isostatic e g tectonic uplift and non isostatic e g glacial isostatic adjustment portions in the current uplift rate of the tibetan plateau if gravity increase associated with ongoing glacial isostatic adjustment partially canceled the negative gravity trend the corrected ice loss rate could reach 61 gt yr 1

improved methods for observing earth s time variable mass distribution with grace using spherical cap mascons we discuss several classes of improvements to gravity solutions from the gravity recovery and climate experiment grace mission these include both improvements in background geophysical models and orbital parameterization leading to the unconstrained spherical harmonic solution jpl rl05 and an alternate jpl rl05m mass concentration mascon solution benefitting from those same improvements but derived in surface spherical cap mascons the mascon basis functions allow for convenient application of a priori information derived from near global geophysical models to prevent striping in the solutions the resulting mass flux solutions are shown to suffer less from leakage errors than harmonic solutions and do not necessitate empirical filters to remove north south stripes lowering the dependence on using scale factors the global mean scale factor decreases by 0 17 to gain accurate mass estimates ocean bottom pressure obp time series derived from the mascon solutions are shown to have greater correlation with in situ data than do spherical harmonic solutions increase in correlation coefficient of 0 08 globally particularly in low latitude regions with small signal power increase in correlation coefficient of 0 35 regionally in addition to reducing the error rms with respect to the in situ data reduction of 0 37 cm globally and as much as 1 cm regionally greenland and antarctica mass balance estimates derived from the mascon solutions agree within formal uncertainties with previously published results computing basin averages for hydrology applications shows general agreement between harmonic and mascon solutions for large basins however mascon solutions typically have greater resolution for smaller spatial regions in particular when studying secular signals

time variability of the earth s gravity field hydrological and oceanic effects and their possible detection using grace the grace satellite mission scheduled for launch in 2001 is designed to map out the earth s gravity field to high accuracy every 2 4 weeks over a nominal lifetime of 5 years changes in the gravity field are caused by the redistribution of mass within the earth and on or above its surface grace will thus be able to constrain processes that involve mass redistribution in this paper we use output from hydrological oceanographic and atmospheric models to estimate the variability in the gravity field i e in the geoid due to those sources we develop a method for constructing surface mass estimates from the grace gravity coefficients we show the results of simulations where we use synthetic grace gravity data constructed by combining estimated geophysical signals and simulated grace measurement errors to attempt to recover hydrological and oceanographic signals we show that grace may be able to recover changes in continental water storage and in seafloor pressure at scales of a few hundred kilometers and larger and at timescales of a few weeks and longer with accuracies approaching 2 mm in water thickness over land and 0 1 mbar or better in seafloor pressure

depositional processes of the suwolbong tuff ring cheju island korea the suwolbong pyroclastic sequence in the western part of cheju island korea comprises partly preserved rim beds of a quaternary basaltic tuff ring whose vent lies about 1 km seaward of the present shoreline the sequence consists of breccia lapillistone lapilli tuff and tuff eighteen sedimentary facies are established and organized into six lateral facies sequences lfs and seven vertical facies sequences vfs the lfs 1 4 and 5 begin with massive lapilli tuff which transforms downcurrent into either planar bedded lfs 1 undulatory bedded lfs 4 or climbing dune bedded lfs 5 lapilli tuff units they are representative of relatively dry base surge whose particle concentration decreases downcurrent with a progressive increase in both tractional processes and sorting the lfs 2 begins with disorganized and massive lapilli tuff and transforms into crudely stratified units downcurrent it results from relatively wet base surge in which sorting is poor due to the cohesion of damp ash the lfs 3 comprises well sorted lapilli tuff and stratified tuff further downcurrent suggestive of deposition from combined fall and surge of relatively dry hydroclastic eruption all seven vertical facies sequences generally comprise two facies units of coarse grained fines depleted lapilli tuff and an overlying fine grained tuff these sequences are suggestive of deposition from base surge that consists of a turbulent head and a low concentration tail depositional processes in the suwolbong tuff ring were dominated by a relatively dry base surge the base surge comprises turbulent and high concentration suspension near the vent whose deposits are generally unstratified due to the lack of tractional transport as the base surge becomes diluted downcurrent through fallout of clasts and mixing of ambient air it develops large scale turbulent eddies and is segregated into coarse grained bedload and overlying fine grained suspension forming thinly stratified units further downcurrent the base surge may be either cooled and deflated or pushed up into the air depending on its temperature the suwolbong tuff ring comprises an overall wet to dry cycle with several dry to wet cycles in it suggestive of overall decrease in abundance of external water and fluctuation in the rate of magma rise

non isotropic gaussian smoothing and leakage reduction for determining mass changes over land and ocean using grace data summary we present a new non isotropic gaussian filter for smoothing mass changes computed from gravity recovery and climate experiment grace l2 products and a new method to reduce land ocean signal leakage caused by gaussian smoothing the kernel of our non isotropic filter is the product of two gaussian functions with distinct latitudinal and longitudinal smoothing radii when expressed as number of kilometres at the earth s surface the longitudinal smoothing radius defined as a fixed longitude interval is longer at the equator and shorter at higher latitude this is principally in accordance with the resolution of the grace data and permits us to produce homogeneously smoothed results without excessive smoothing in latitudinal direction this filter is not applicable in polar regions where we choose to use the classical isotropic gaussian filter a smoothing radius choice scheme is proposed for the two filters to mesh seamlessly in our leakage reduction method the inputs are the mass change data after smoothing using a gaussian filter along coasts where mass change signal on land is far larger than that over ocean or signal over ocean is reduced to a very small magnitude by removing a model beforehand and adding the model back afterwards our method approximately recovers a smoothed mass change signal over both land and ocean sides as if a regional gaussian filter with the same smoothing radius were applied over land and ocean separately in which no signal leakages appear the side lobe problem does not appear in our approach our leakage reduction method could also be used to study mass changes within a region where signal is far larger than that in surrounding regions or where signal in surrounding regions could be reduced to very low magnitude by removing a model

lower satellite gravimetry estimates of antarctic sea level contribution a new model of glacial isostatic adjustment used in conjunction with grace satellite data suggests that ice loss from antarctica is contributing 0 19 millimetres per year to global mean sea level which is substantially less than previous grace based estimates estimates for recent mass loss from antarctica vary widely making it difficult to calculate any subsequent contributions to sea level rise one prominent approach uses the grace gravity recovery and climate experiment satellites to detect changes in gravity but the final estimates are dependent on the modelled response of the continent to changes in ice loading over time and to changes in lithospheric elastic rebound matt king and colleagues apply a new model of this glacial isostatic adjustment to the grace data and estimate antarctic mass loss between 2002 and 2010 to be about 69 gigatonnes per year much lower than previous estimates and equivalent to an annual sea level rise of about 0 2 millimetres recent estimates of antarctica s present day rate of ice mass contribution to changes in sea level range from 31 gigatonnes a year gt yr 1 ref 1 to 246 gt yr 1 ref 2 a range that cannot be reconciled within formal errors3 time varying rates of mass loss2 4 5 6 contribute to this but substantial technique specific systematic errors also exist3 in particular estimates of secular ice mass change derived from gravity recovery and climate experiment grace satellite data are dominated by significant uncertainty in the accuracy of models of mass change due to glacial isostatic adjustment7 8 gia here we adopt a new model of gia developed from geological constraints which produces gia rates systematically lower than those of previous models and an improved fit to independent uplift data9 after applying the model to 99 months from august 2002 to december 2010 of grace data we estimate a continent wide ice mass change of 69 18 gt yr 1 0 19 0 05 mm yr 1 sea level equivalent this is about a third to a half of the most recently published grace estimates2 5 which cover a similar time period but are based on older gia models plausible gia model uncertainties and errors relating to removing longitudinal grace artefacts destriping confine our estimate to the range 126 gt yr 1 to 29 gt yr 1 0 08 0 35 mm yr 1 sea level equivalent we resolve 26 independent drainage basins and find that antarctic mass loss and its acceleration is concentrated in basins along the amundsen sea coast outside this region we find that west antarctica is nearly in balance and that east antarctica is gaining substantial mass

antarctica greenland and gulf of alaska land ice evolution from an iterated grace global mascon solution we have determined the ice mass evolution of the antarctica and greenland ice sheets ais and gis and gulf of alaska goa glaciers from a new grace global solution of equal area surface mass concentration parcels mascons in equivalent height of water the mascons were estimated directly from the reduction of the inter satellite k band range rate kbrr observations taking into account the full noise covariance and formally iterating the solution the new solution increases signal recovery while reducing the grace kbrr observation residuals the mascons were estimated with 10 day and 1 arc degree equal area sampling applying anisotropic constraints an ensemble empirical mode decomposition adaptive filter was applied to the mascon time series to compute annual mass balances the details and causes of the spatial and temporal variability of the land ice regions studied are discussed the estimated mass trend over the total gis ais and goa glaciers for the time period 1 december 2003 to 1 december 2010 is 380 plus or minus 31 gt a exp 1 equivalent to 1 05 plus or minus 0 09 mma exp 1 sea level rise over the same time period we estimate the mass acceleration to be 41 plus or minus 27 gt a exp 2 equivalent to a 0 11 plus or minus 0 08 mm a exp 2 rate of change in sea level the trends and accelerations are dependent on significant seasonal and annual balance anomalies

grace derived ice mass variations over greenland by accounting for leakage effects 1 after more than 6 years in full operational mode the gravity recovery and climate experiment grace satellite mission provides the opportunity to derive global secular mass changes from space geodetic observations crucial for a reliable estimate of secular mass changes is the ability to correct for spectral and spatial leakage effects in order to account for any leakage signal we present and apply a four step procedure including a validation step based on forward gravity modeling most notably our method is characterized by the separation and quantification of individual leakage sources we test and apply our procedure to the greenland area which exhibits the strongest secular trend signal on the basis of simulation studies we demonstrate that leakage out effects are dominant for the greenland area and if not accounted for mass change rates will be underestimated analyzing time variable grace gravity fields covering 6 whole years august 2002 to july 2008 inclusive we estimate the ice volume loss over greenland to be 177 12 km3 a 1 this value is the average derived from monthly gravity field models provided by csr gfz and jpl with individual contributions of 242 14 km3 a 1 194 24 km3 a 1 and 96 23 km3 a 1 respectively we highlight that without taking leakage effects into account mass change amplitudes over greenland are reduced by a factor of 2 despite the rather large spread of the results among grace processing centers our results are in better agreement with the findings from alternative grace analysis methods and insar observations

the fekete hegy balaton highland hungary soft substrate and hard substrate maar volcanoes in an aligned volcanic complex implications for vent geometry subsurface stratigraphy and the palaeoenvironmental setting the fekete hegy volcanic complex is located in the centre of the bakony balaton highland volcanic field in the pannonian basin which formed from the late miocene to pliocene period the eruption of at least four very closely clustered maar volcanoes into two clearly distinct types of prevolcanic rocks allows the observation and comparison of hard substrate and soft substrate maars in one volcanic complex the analyses of bedding features determination of the proportion of accidental lithic clasts granulometry and age determination helped to identify and distinguish the two types of maar volcanoes ascending magma interacted with meteoric water in karst aquifers in mesozoic carbonates as well as in porous media aquifers in neogene unconsolidated wet siliciclastic sediments the divided basement setting is reflected by distinct bedding characteristics and morphological features of the individual volcanic edifices as well as a distinct composition of pyroclastic rocks country rocks in hard substrate maars have a steep angle of repose leading to the formation of steep sided cone shaped diatremes enlargement and filling of these diatreme is mainly a result of shattering material by fci related shock waves and wall rock collapse during downward penetration of the explosion locus country rocks in soft substrate maars have much shallower angles of repose leading to the formation of broad bowl shaped structures or irregular depressions enlargement and filling of these diatremes is mainly the result of substrate collapse for example due to liquefaction of unconsolidated material by fci related shock waves and its emplacement by gravity flows the fekete hegy is an important example illustrating that the substrate of a volcanic edifice has to be taken into account as an important interface which can have major control on phreatomagmatic eruptions and the resulting characteristics of the volcanic complex

acceleration of greenland ice mass loss in spring 2004 in 2001 the intergovernmental panel on climate change projected the contribution to sea level rise from the greenland ice sheet to be between 0 02 and 0 09 m from 1990 to 2100 ref 1 however recent work has suggested that the ice sheet responds more quickly to climate perturbations than previously thought particularly near the coast here we use a satellite gravity survey by the gravity recovery and climate experiment grace conducted from april 2002 to april 2006 to provide an independent estimate of the contribution of greenland ice mass loss to sea level change we detect an ice mass loss of 248 36 km3 yr 1 equivalent to a global sea level rise of 0 5 0 1 mm yr 1 the rate of ice loss increased by 250 per cent between the periods april 2002 to april 2004 and may 2004 to april 2006 almost entirely due to accelerated rates of ice loss in southern greenland the rate of mass loss in north greenland was almost constant continued monitoring will be needed to identify any future changes in the rate of ice loss in greenland

computations of the viscoelastic response of a 3 d compressible earth to surface loading an application to glacial isostatic adjustment in antarctica and canada s u m m a r y we develop a 3 d finite element model to study the viscoelastic response of a compressible earth to surface loads the effects of centre of mass motion polar wander feedback and selfconsistent ocean loading are implemented to assess the model s accuracy we benchmark the numerical results against a semi analytic solution for spherically symmetric structure we force our model with the ice 5g global ice loading history to study the effects of laterally varying viscosity structure on several glacial isostatic adjustment gia observables including relative sea level rsl measurements incanada and present day time variable gravity and uplift rates in antarctica canadian rsl observations have been used to determine the earth s globally averaged viscosity profile antarcticgps uplift rates have been used to constrainantarcticgia models and gia time variable gravity and uplift signals are error sources for grace and altimeter estimates of present day antarctic ice mass loss and must be modelled and removed from those estimates computinggia results for a 3 d viscosity profile derived from a realistic seismic tomography model and comparing with results computed for 1 d averages of that 3 d profile we conclude that 1 a gia viscosity model based on canadian relative sea level data is more likely to represent a canadian average than a true global average 2 the effects of 3 d viscosity structure on grace estimates of present day antarctic mass loss are probably smaller than the difference between gia models based on different antarctic deglaciation histories and 3 the effects of 3 d viscosity structure on antarctic gps observations of present day uplift rate can be significant and can complicate efforts to use gps observations to constrain 1 d gia models

long term and seasonal caspian sea level change from satellite gravity and altimeter measurements we examine recent caspian sea level change by using both satellite radar altimetry and satellite gravity data the altimetry record for 2002 2015 shows a declining level at a rate that is approximately 20 times greater than the rate of global sea level rise seasonal fluctuations are also much larger than in the world oceans with a clearly defined geographic region and dominant signal magnitude variations in the sea level and associated mass changes provide an excellent way to compare various approaches for processing satellite gravity data an altimeter time series derived from several successive satellite missions is compared with mass measurements inferred from gravity recovery and climate experiment grace data in the form of both spherical harmonic sh and mass concentration mascon solutions after correcting for spatial leakage in grace sh estimates by constrained forward modeling and accounting for steric and terrestrial water processes grace and altimeter observations are in complete agreement at seasonal and longer time scales including linear trends this demonstrates that removal of spatial leakage error in grace sh estimates is both possible and critical to improving their accuracy and spatial resolution excellent agreement between grace and altimeter estimates also provides confirmation of steric caspian sea level change estimates grace mascon estimates both the jet propulsion laboratory jpl coastline resolution improvement version 2 solution and the center for space research csr regularized are also affected by leakage error after leakage corrections both jpl and csr mascon solutions also agree well with altimeter observations however accurate quantification of leakage bias in grace mascon solutions is a more challenging problem

a reconciled estimate of glacier contributions to sea level rise 2003 to 2009 glaciers distinct from the greenland and antarctic ice sheets are losing large amounts of water to the world s oceans however estimates of their contribution to sea level rise disagree we provide a consensus estimate by standardizing existing and creating new mass budget estimates from satellite gravimetry and altimetry and from local glaciological records in many regions local measurements are more negative than satellite based estimates all regions lost mass during 2003 2009 with the largest losses from arctic canada alaska coastal greenland the southern andes and high mountain asia but there was little loss from glaciers in antarctica over this period the global mass budget was 259 28 gigatons per year equivalent to the combined loss from both ice sheets and accounting for 29 13 of the observed sea level rise

the influence of palaeotopography on facies architecture and pyroclastic flow processes of a lithic rich ignimbrite in a high gradient setting the abrigo ignimbrite tenerife canary islands abstract the late pleistocene 188 19 ka abrigo ignimbrite represents the last major explosive caldera forming eruption on tenerife it consists almost entirely of a moderate volume 1 8 km 3 light grey phonolitic lithic rich ignimbrite deposit although a possible abrigo member thin fall deposit is locally preserved beneath the ignimbrite suggesting an initial short lived stable plinian eruption column the ignimbrite deposit is dispersed radially around the lower flanks of the las canadas edifice and correlates to a clast supported lithic breccia on the eastern and northern caldera wall much of the ignimbrite was probably deposited offshore or within the caldera now buried by more recent lavas two major depositional units separated by a co ignimbrite ash cloud deposit and which display dramatic variations in thickness pyroclastic flows were channelised along and deposited within the same valleys that exist today and were commonly continuous and sheet like across the interfluves the basal zones of pyroclastic flows are envisaged as a bed load of coarse lithic lapilli and blocks transported under their own momentum and with the support of the surrounding fine ash gas granular flow

evaluation of glacier changes in high mountain asia based on 10 year grace rl05 models in this paper 10 years of time variable gravity data from the gravity recovery and climate experiment release 05 have been used to evaluate the glacier melting rate in high mountain asia hma using a new computing scheme i e the space domain inverse method we find that in hma area there are three different kinds of signal sources that should be treated together the two generally accepted sources glacier melting and india underground water depletion are estimated to change at the rate of 35 0 5 8 gt yr 0 09 mm yr sea level rising and 30 6 5 0 gt yr respectively the third source is the remarkable positive signal 30 gt yr in the inner tibetan plateau which is challenging to explain further we have found that there is a 5 year undulation in pamir and karakoram which can explain the controversies of the previous studies on the glacier melting rate here this 5 year signal can be explained by the influence of arctic oscillation and el nino southern oscillation

deep seismic images and the tectonic framework of early rifting in the otway basin australian southern margin abstract the otway basin is one of a number of basins formed along australia s southern continental margin during the late jurassic early cretaceous rifting of australia from antarctica it lies on a transitional area of extended lithosphere between the margin to the west where continental separation took place close to the australian craton and the region to the east where separation failed to develop through bass strait but instead switched to the south of tasmania seven agso regional deep seismic profiles recorded during 1992 across onshore parts of the basin provide images of synrift basin bounding faults that dip predominantly towards the continent basin sequences in half graben rift segments at two way times greater than 4 s and mid crustal detachments with ramp and flat geometry at mid crustal levels when combined with industry seismic data trend variations on faults indicate that extensional strain direction varied along the rift system probably locally controlled by pre existing palaeozoic geology but consistent with general north south lithospheric extension basement highs between some of the rift segments are interpreted as accommodation or transfer zones multiple basin bounding faults in some places mirror features within basement and may indicate a component of local strike slip during early rifting the syn rift segments form part of the first stage early cretaceous failed rift system in the otway bass strait region crustal thickness is interpreted to be 31 km 10 3 10 5 s twt near the northern basin margin thinning to about 25 km 9 s twt 40 reduction in thickness of palaeozoic crust seaward of the tartwaup fault zone this fault zone and the timboon fault system farther east are interpreted to be headwall faults landward limit of a late cretaceous second stage rifting system along a lower plate margin which ultimately separated australia from antarctica

volcano tectonic setting of the intraplate pliocene holocene newer volcanic province southeast australia role of crustal fracture zones 1 the pliocene holocene newer volcanic province in victoria southeast australia is a wide volcanic field site of the most recent volcanic activity of australia the intraplate signature and the localization on the northern side of the southern ocean have been used in the past to ascribe the volcanic activity either to the presence of a mantle hot spot or to thermal anomalies inherited from the seafloor spreading that separated australia from antarctica during the gondwana breakup the spacing and distribution of groups of eruption points suggests the presence of a 32 km deep mantle thermal anomaly alignments of eruption points indicate a strong tectonic control on magma emplacement mainly along nw se mesozoic cenozoic structures and along n s palaeozoic and e w late cretaceous structures this volcano tectonic setting relates to the interference of the left lateral kinematics of the major n s trending faults associated with the tasman fracture zone and the extensional structures of the otway basin this interpretation is also coherent with stress in situ data and focal mechanisms of earthquakes shmax oriented n150 this interpretation enhances the role of the tasman fracture zone a major sinistral transform on the reactivation of transtensional structures and on triggering the magmatism of the newer volcanic province

magma water interactions in subaqueous and emergent basaltic in the subaqueous growth and emergence of a basaltic volcano clasts are formed by one or a combination of 1 explosive release of magmatic volatiles 2 explosive expansion and collapse of steam formed at magma water contact surfaces 3 explosive expansion of steam following enclosure of water in magma or entrapment of water close to magma and 4 cooling contraction these processes named respectivelymagmatic explosivity contact surface steam explosivity bulk interaction steam explosivity andcooling contraction granulation can be enhanced by mutual interaction and feedback the first three explosive processes are limited at certain water depths hydrostatic pressures and become increasingly vigorous at shallower levels the depth of onset of magmatic explosivity depends largely on juvenile volatile content it is up to 200 m for tholeiitic magmas and up to 1 km for alkalic magmas at the depth where formation of clastic deposits becomes predominant over effusion of lavas magmatic explosivity is subordinate to steam explosivity as a clast forming process the upward transition to accumulation of dominantly clastic deposits is not simply related to the onset of substantial exsolution of magmatic volatiles and can occur without it contact surface explosivity commonly requires initiation by a vigorous impact between magma and water and although no certain depth limit is known likelihood of such explosivity decreases rapidly with depth clast generation by bulk interaction explosivity appears to be restricted to depths much shallower than that of the critical pressure of water which in sea water is at about 3 km cooling contraction granulation can occur in any depth of water but at shallow levels may be replaced by contact surface explosivity during continuous eruption under water tephra can be ejected and deposited within a cupola of steam such that rapid quenching does not occur emergent volcanoes are characterized by distinctive steam explosive activity that results primarily from a bulk interaction between rapidly ascending magma and a highly mobile slurry of clastic material water and steam the water gets into the vent by flooding across or through the top of the tephra pile and violent explosions cease when this access is sealed the eruptions during emergence of surtsey and capelinhos typify the distinctive explosive activity the style and controls of which are different from those of maar volcanoes

estimating geocenter variations from a combination of grace and ocean model output 1 in this study we estimate a time series of geocenter anomalies from a combination of data from the gravityrecoveryandclimateexperiment grace satellitemissionandthe outputfromoceanmodels amatrixequationisderivedrelating totalgeocentervariations to the grace coefficients of degrees two and higher and to the oceanic component of the degree one coefficients we estimate the oceanic component from two state of the art ocean models results are compared to independent estimates of geocenter derived from other satellite data such as satellite laser ranging and gps finally we compute degree one coefficients that are consistent with the processing applied to the grace level 2 gravity field coefficients the estimated degree one coefficients can be used to improve estimates of mass variability from grace which alone cannot provide them directly

an ignimbrite veneer deposit the trail marker of a pyroclastic flow abstract the term ignimbrite veneer deposit ivd is proposed for a new kind of pyroclastic deposit which is found associated with and passes laterally into taupo ignimbrite of valley pond type in new zealand it forms a thin layer mantling the landscape over 15 000 km 2 and is regarded as the deposit from the trailing tail of a pyroclastic flow where a relaxation of shear stress favoured the deposition of the basal part of the flow the ivd differs little in grain size from the associated ignimbrite but it shows a crude internal stratification attributed to the deposition of a succession of layers one after the passage of each pulse of the pyroclastic flow it locally contains laterally discontinuous lenses of coarse pumice lee side lenses on the far vent side of topographic obstacles in nearvent exposures the taupo ivd shows lensoid and cross stratified bed forms even where it stands on a planar surface attributed to deposition from a flow travelling at an exceedingly high velocity an ivd can be distinguished from a poorly sorted pyroclastic fall deposit because the beds in it show more rapid lateral variations in thickness it may show a low angle cross stratification and it contains carbonised wood from trees not in the position of growth from the deposit of a wet base surge because it lacks vesicles and strong antidune like structures and contains carbonised vegetation and from a hot and dry pyroclastic surge deposit because it possesses a high content of pumice and fines the significance of an ivd is that it records the passage of a pyroclastic flow where the flow itself has moved farther on

evolution and hydrological conditions of a maar volcano atexcac crater eastern mexico abstract the atexcac maar is located in the central part of the serdan oriental lacustrine playa basin in the eastern mexican volcanic belt it is part of a dispersed and isolated monogenetic field consisting of maar volcanoes basaltic cinder cones and rhyolitic domes atexac is a maar volcano excavated into pyroclastic deposits basaltic lava flows and the flanks of a cinder cone cluster which itself was built on a topographic high consisting of limestone it has an ene trending elliptical shape with beds mostly unconsolidated deposits that dip outward at 16 22 the atexcac crater was formed from vigorous phreatomagmatic explosions in which fluctuations in the availability of external water temporal migration of the locus of the explosion and periodic injection of new magma were important controls on the evolution of the maar crater variations in grain sizes and component proportions of correlated deposits from the different sections suggest a migration of the locus of explosions producing different eruptive conditions with fluctuating water magma interactions deposits rich in large intrusive and limestone blocks are associated with a matrix enriched in small andesitic lapilli this could suggest differential degrees of fragmentation due to inherited previously acquired fragmentation and or relative distance to the locus of explosions initial short lived phreatic explosions started at the southwest part of the crater and were followed by an ephemeral vertical column and the influx of external water that led to relatively shallow explosive interactions with the ascending basaltic magma drier explosions progressed downward and or laterally northward sampling subsurface rock types particularly intrusive limestone and andesitic zones as well as localized altered zones n ne caused by repetitive injection of basaltic magma a final explosive phase involved a new injection of magma and a new influx of external water producing wetter conditions at the end of the maar formation we infer the aquifer was formed by fractured rocks predominantly andesitic lava flows and limestone rocks andesitic accessory clasts dominate in all stratigraphic levels but these rocks are not exposed in the nearby area these local hydrogeological conditions contrast with those at nearby maar volcanoes where the water for the magma water interactions apparently mostly came from a dominantly unconsolidated tuffaceous aquifer producing tuff rings with a much lower profile than atexcac

contribution of ice sheet and mountain glacier melt to recent sea level rise altimeter data suggest that sea level rose by about 2 4 mm per year from 2005 to 2011 but estimates of the relative contributions of ocean warming and increased ocean mass are equivocal an analysis of ocean temperature and satellite gravity data suggests that the delivery of meltwater from ice sheets and mountain glaciers contributed 75 of the observed sea level rise

the origin of a large 3 km maar volcano by coalescence of multiple shallow craters lake purrumbete maar southeastern australia lake purrumbete maar is located in the intraplate monogenetic newer volcanics province in southeastern australia the extremely large crater of 3000 m in diameter formed on an intersection of two fault lines and comprises at least three coalesced vents the evolution of these vents is controlled by the interaction of the tectonic setting and the properties of both hard and soft rock aquifers lithics in the maar deposits originate from country rock formations less than 300 m deep indicating that the large size of the crater cannot only be the result of the downwards migration of the explosion foci in a single vent vertical crater walls and primary inward dipping beds evidence that the original size of the crater has been largely preserved detailed mapping of the facies distributions the direction of transport of base surges and pyroclastic flows and the distribution of ballistic block fields form the basis for the reconstruction of the complex eruption history which is characterised by alternations of the eruption style between relatively dry and wet phreatomagmatic conditions and migration of the vent location along tectonic structures three temporally separated eruption phases are recognised each starting at the same crater located directly at the intersection of two local fault lines activity then moved quickly to different locations a significant volcanic hiatus between two of the three phases shows that the magmatic system was reactivated the enlargement of especially the main crater by both lateral and vertical growth led to the interception of the individual craters and the formation of the large circular crater lake purrumbete maar is an excellent example of how complicated the evolution of large seemingly simple circular maar volcanoes can be and raises the question if these systems are actually monogenetic

post eruptive development of the ukinrek east maar since its eruption in 1977 a d in the periglacial area of south west alaska maar eruptions form small initially steep walled basins that contain important archives for the climatic and palaeoenvironmental history in continental areas the two ukinrek maars in south western alaska erupted between 30 march and 9 april 1977 and are the best documented maars that have erupted in historical time this study presents a preliminary analysis of geomorphology hydrology magnetic susceptibility geochemistry and sedimentology data of a field study in august 2004 these results photographs and topographic surveys are combined for reconstructing the post eruptive evolution of ukinrek east maar within less than 30 years the initially polygonal shape of the crater with nearly vertical crater walls has developed into an almost elliptic form with slopes of 35 inclination on debris fans between a few escarpments the water table and the crater floor have risen significantly and the crater diameter depth ratio increased from 3 4 to 5 7 whereas the average height of the crater rim remained almost constant the main sub aerial resedimentation process is formation of rock falls rock slumps and scree resulting in debris flows and turbidites within the lake that is ice covered throughout about half of the year distal lake sediments consist of laminated minerogenic clayey sandy silts that document frequent turbidity currents from the linear sedimentation rate of only ca 5 mm year 1 in 17 cm long cores it may be concluded that the largest portion of the crater sediments formed within the first few months of the maar history however this has to be confirmed by future studies

detection of sea level fingerprints derived from grace gravity data mass changes of ice sheets glaciers ice caps land water hydrology atmosphere and ocean cause a non uniform sea level rise due to the gravitational and self attraction and loading effects called sea level fingerprints slf slf have been previously derived from a combination of modeled and observed mass fluxes from the continents into the ocean here we derive improved slf from time series of time variable gravity data from the grace mission for april 2002 october 2014 we evaluate the grace derived slf using ocean bottom pressure obp data from stations in the tropics where obp errors are the lowest we detect the annual phase of the slf in the obp signal and separate it unambiguously from the barystatic sea level bsl at two stations at the basin scale the slf explain a larger fraction of the variance in steric corrected altimetry than the bsl which has implications for evaluating mass transport between ocean basins

base surge deposits eruption history and depositional processes of a wet phreatomagmatic volcano in central anatolia cora maar abstract cora maar is a quaternary volcano located to the 20 km northwest of mount erciyes the largest of the 19 polygenetic volcanic complexes of the cappadocian volcanic province in central anatolia cora maar is a typical example of a maar diatreme volcano with a nearly circular crater with a mean diameter of c 1 2 km and a well bedded base surge dominated maar rim tephra sequence up to 40 m in thickness having a diameter depth ratio d d of 12 cora is a relatively mature maar compared to recent maar craters in the world cora crater is excavated within the andesitic lava flows of quaternary age the tephra sequence is not indurated and consists of juvenile clasts up to 70 cm non juvenile clasts up to 130 cm accretionary lapilli up to 1 2 cm in diameter and ash to lapilli sized tephra base surge layers display well developed antidune structures indicating the direction of the transport both progressive and regressive dune structures are present within the tephra sequence wavelength values increase with increasing wave height and with large wavelength and height values cora tephra display similarities to taal and laacher see base surge deposits impact sags and small channel structures are also common lateral and vertical facies changes are observed for the dune bedded and planar bedsets according to granulometric analyses cora maar tephra samples display a bimodal distribution with a wide range of md values characteristic for the surge deposits very poorly sorted bimodal ash deposits generally vary from coarse tail to fine tail grading depending on the grain size distribution while very poorly sorted lapilli and block rich deposits display a positive skewness due to fine tail grading

origin of the joya honda maar san luis potosi mexico abstract joya honda is a quaternary maar of unusual type from the mexican basin and range province its 300 m deep crater is excavated in cretaceous limestones the surrounding tephra deposit which in places is 100 m thick begins with a series of weakly indurated pyroclastic surge and fall layers that we interpret as dry surge deposits these are overlain by the main sequence of strongly indurated massive tuff breccias that we interpret as wet surge deposits joya honda formed subaerially from the interaction of groundwater with rapidly ascending intraplate type basanitic magma carrying peridotitic mantle xenoliths local aquifer characteristics controlled the style of eruption and the nature of the deposits groundwater in the limestone hosted aquifer beneath joya honda was apparently contained within solution enhanced fractures at the onset of the eruption magma began to interact with a moderate amount of groundwater producing the dry surge deposits which are typical of deposits found at many maars and tuff rings as the eruption continued the crater grew and the hydromagmatic blasts fractured the limestones around the explosion foci a marked increase in the water magma ratio of the system followed when a large fracture or a portion of the limestone with enhanced secondary permeability was intersected by the expanding crater subsequent phreatomagmatic explosions occurred in a system with groundwater flow rates several orders of magnitude larger than in the initial dry surge stage at the maar rim these wet eruptions led to the emplacement of massive tuff breccias through a combination of fallout surges and mudflows these steeply dipping tuff breccias are similar to deposits found at many tuff cones juvenile clasts in the near vent deposits show marked upward increases in both hydration palagonitization and vesicularity the increased palagonitization with height in the section appears to be a consequence of the overall increased wetness of the eruption with time correlating with greater carbonate cementation and lithification in the upper part of the deposit the transition toward higher vesicularity is interpreted as evidence of a gradual reduction in the confining pressure for the ascending magma prior to explosive fragmentation perhaps related to unroofing during progressive excavation of the overlying maar crater thus joya honda does not support maar formation models that invoke downward displacement of explosion foci caused by formation of a cone of depression in the aquifer in order to maintain the confining pressure for the hydromagmatic blasts