changing features of the climate and glaciers in china s monsoonal temperate glacier region 1 climatic data ice core records the tree ring index and recorded glacier variations have been used to reconstruct a history of climatic and glacial changes in the monsoonal temperate glacier region of southwestern china during the last 400 years the region s temperature has increased in a fluctuating manner during the twentieth century after two cold stages of the little ice age seventeenth to nineteenth centuries with a corresponding retreat of most of the glaciers against a background of global warming retreat rates accelerated after the 1980s the few advancing glaciers that did exist have started to retreat in recent years the amount trend and amplitude of variation of precipitation have differed in different parts of the region the dasuopu ice core from the western part of the region shows a decreasing trend in precipitation the converse of the trend in temperature in the eastern part of the region however a rising trend of rainfall has accompanied increasing temperatures as a result of the variable atmospheric circulations from different sources the southwest monsoon the principal controlling factor in the chinese monsoonal temperate glacier region can be classified into the indian monsoon and the bengal monsoon the former passes across the indian peninsula from the arabian sea and transports vapor for precipitation in the western part of the monsoonal temperate glacier region the bengal monsoon originating in the bay of bengal is the major source of precipitation in the eastern part of the region the eastern part is also influenced by the southeast monsoon arriving from the western pacific and the western part is affected in winter by the southern branch of the westerly circulation this complex atmospheric situation results in differing patterns of precipitation in the western and eastern zones although it is clear that both temperature and precipitation affect the glaciers further work is needed to confirm which of these is the major factor influencing present glacier change

comparative lahar hazard mapping at volcan citlaltepetl mexico using srtm aster and dted 1 digital topographic data abstract in this study we evaluated and compared the utility of spaceborne srtm and aster dems with baseline dted 1 bald earth topography for mapping lahar inundation hazards from volcan citlaltepetl mexico a volcano which has had a history of producing debris flows of various extents in particular we tested the utility of these topographic datasets for resolving ancient valley filling deposits exposed around the flanks of the volcano for determining their magnitude using paleohydrologic methods and for forecasting their inundation limits in the future we also use the three datasets as inputs to a gis stream inundation flow model laharz and compare the results in general all three datasets with spatial resolution of 90 m or better were capable of resolving debris flow and lahar deposits at least 3 106 m3 in volume or larger canopy and slope related height errors in the aster and srtm dems limit their utility for measuring valley filling cross sectional area and deriving flow magnitude for the smallest deposits using a cross sectional area to volume scaling equation height errors in the aster and srtm dems also causes problems in resolving stream valley hydrography which controls lahar flow paths and stream valley morphology which controls lahar filling capacity however both of the two spaceborne dem datasets are better than dted 1 at resolving fine details in stream hydrography and erosional morphologies of volcaniclastics preserved in the valleys around the more humid eastern flanks of the volcanic range the results of laharz flow inundation modeling using all three dems as inputs are remarkably similar and co validate one another for example at citlaltepetl all lahar simulations show that the city of orizaba is the most vulnerable to flows similar in magnitude to or larger than one that occurred in 1920 many of the other cities and towns illustrated are built higher up on terrace deposits of older debris flows and are safe from all but the largest flows which occur less frequently finally asters 60 km swath width and 8 duty cycle presents a challenge for mapping lahar inundation hazards at e w oriented stream valleys in low latitude areas with persistent cloud cover however its continued operations enhances its utility as a means for updating the continuous but one time coverage of srtm and for filling voids in the srtm dataset such as those that occur along steep sided valleys prone to hazards from future lahars

seasonal diurnal and storm scale hydrochemical variations of typical epikarst springs in subtropical karst areas of sw china soil co2 and dilution effects summary two year continuous ph conductivity temperature and water stage of the two typical epikarst springs nongla spring and maolan spring about 200 km apart in subtropical karst areas of sw china were presented our primary study objective was to understand how karst systems respond hydrochemically to recharge at different time scales and what the biogeochemical processes and controlling factors in the sw china epikarst environment are a thermodynamic model was used to link the continuous data to monthly water quality data allowing the calculation of co 2 partial pressures and calcite dolomite saturation levels on a continuous basis marked seasonal diurnal and storm scale variations were observed for ph conductivity co 2 partial pressures and calcite dolomite saturation indexes of the springs indicating that both springs are dynamic and variable systems however the coefficients of variation of these hydrogeochemical features tends to be in the order of seasonal storm scale diurnal the seasonal and diurnal variations of these features higher conductivity and lower ph in summer and at daytime lower conductivity and higher ph in winter and at nighttime tend to co vary with temperature which influences the production of co 2 in soils thus being the driving force for the variations soil co 2 effect the storm scale fluctuations occur during the spring summer rainy days due to the storm events depending on the rainfall intensities however there are differences in magnitudes and direction of the variations of these features at very high rainfall intensity the dilution effect dominates the variations characterized by the decrease in both conductivity and calcite dolomite saturation of the springs while soil co 2 effect determines the variations at lower rainfall intensity characterized by increase in co 2 partial pressure and conductivity but decrease in ph and calcite dolomite saturation in a word the hydrodynamic aspects together with hydrobiogeochemical characteristics need to be taken into account to correctly explain the hydrochemical variations of the epikarst springs results from the study demonstrate the need to redesign hydrogeochemical sampling strategies for epikarst springs in karst areas with monsoon climate like sw china i e with remarkable seasonal matching fluctuations in temperature rainfall and vegetation

numerical modeling of the emplacement of socompa rock avalanche chile 1 the 7 5 ka socompa sector collapse emplaced 25 km3 of fragmented rock as a thin but widespread 500 km2 avalanche deposit followed by late stage sliding of 11 km3 as toreva blocks most of the avalanche mass was emplaced dry although saturation of a basal shear layer cannot be excluded modeling was carried out using the depth averaged granular flow equations in order to provide information on the flow behavior of this well preserved long run out avalanche results were constrained using structures preserved on the surface of the deposit as well as by deposit outline and run up a proxy for velocity models assuming constant dynamic friction fail to produce realistic results because the low basal friction angles 1 to 3 5 necessary to generate observed run out permit neither adequate deposition on slopes nor preservation of significant morphology on the deposit surface a reasonable fit is obtained however if the avalanche is assumed simply to experience a constant retarding stress of 50 100 kpa during flow this permits long run out as well as deposition on slopes and preservation of realistic depositional morphology in particular the model explains a prominent topographic escarpment on the deposit surface as the frozen front of a huge wave of debris reflected off surrounding hills the result that socompa avalanche experienced a small approximately constant retarding stress during emplacement is consistent with a previously published analysis of avalanche data

ferroan alkalic volcanism associated with calymmian rifting in the paramirim aulacogen sao francisco craton brazil new insights from lithofacies analysis and evidence of mantle derived alkaline h2o rich metasomatic fluids affecting ancient crustal materials abstract rift related volcanism is widely used in models of supercontinent reconstruction while the associated metasomatic fluids provide information about the mantle crust process during intracrustal melting events the paleoproterozoic mesoproterozoic paramirim aulacogen corresponds to multiple intracratonic rift cycles that register many basin developing events intense volcanic activity is recorded in some rift events but the volcanic lithofacies and their petrogenesis are poorly constrained herein we present lithofaciological characterization whole rock and mineral chemistry and u pb and lu hf isotope data from the 1 58 ga volcanic rocks trachytic and trachy andesitic lava flows and primary to secondary volcaniclastic lithotypes characterize this volcanism the primary volcaniclastic rocks resulted from direct volcanic activity and can be divided into pyroclastic and hydroclastic lithofacies associations the pyroclastic lithotypes correspond to air fall density currents and block and ash flow deposits formed in explosive eruptions hydroclastic lithotypes are represented by hyaloclastites and peperites reflecting effusive eruptions and interactions between magma water and sediments the secondary volcaniclastic lithotypes resulted from late stage reworking processes and consist of debris flows ephemeral streams associated with high energy and gravitational flow deposits the lava flows show well preserved primary volcanic features such as magma flow textures and euhedral phenocrysts based on petrographic and chemical characteristics associated with negative hf t values we infer that high melt rate of an ancient crust previously metasomatized by h2o rich alkaline mantle derived fluids generated the alkalic ferroan lavas these fluids promoted potassic and sodic metasomatism that affected all the volcanic rocks modifying the chemistry of the feldspars to pure orthoclase or96 98 and albite ab98 100 in some lavas a higher concentration of na rich fluids synthesized aegirine at a minimum temperature of 200 c and promoted its peralkaline character the potassic sodic metasomatism influenced the volcano sedimentary sequence of the pajeu group and the oldest rocks of the basement but did not affect the overlying sedimentary sequences indicating that fluids ceased with the end of volcanism we suggest that the h2o rich alkaline fluids arose by focused degassing in response to a rising asthenospheric mantle during the calymmian rift of the paramirim aulacogen

improving insar elevation models in antarctica using laser altimetry accounting for ice motion orbital errors and atmospheric delays abstract ice dynamics is closely related to climate change however a lack of digital elevation models dems of sufficient horizontal resolution and vertical precision has been a major issue in dynamic studies for years existing antarctic dems are derived from satellite radar and laser altimetry as well as limited terrestrial data these sparse datasets result in poor spatial resolution hundreds of metres to 1 km in this paper we propose a method for generating high accuracy and high resolution dems using interferometric synthetic aperture radar insar and ice cloud and land elevation satellite icesat laser altimetry by reducing the influence of ice motion satellite orbital errors and topographically correlated atmospheric delays a case study in the grove mountains area shows that the insar dem has a root mean square rms error of 5 9 m which is better than the radarsat antarctic mapping project ramp 21 1 m and bamber 8 5 m dems the new dem is used to calculate ice velocity over the grove mountains area where gps measurements have been collected for comparison compared to the nasa making earth system data records for use in research environments measures insar based antarctica ice velocity map ice velocity estimates from long baseline interferogram and the new dem have a smaller rms error this suggests that with the new dem baseline length is no longer a limiting factor for the accuracy of insar based ice velocity mapping

global chemical erosion during the last glacial maximum and the present sensitivity to changes in lithology and hydrology geographically based calculations for 18 000 years ago 18 ka and today were made to examine the potential effects on terrestrial chemical erosion of changes in lithology and hydrology on glacial interglacial timescales runoff fields were derived from general circulation model predictions of precipitation minus evaporation then global lithologic maps were prepared so that empirical relationships for runoff versus bicarbonate flux for different rock types could be used to calculate global chemical erosion rates assuming that significant chemical erosion does not occur beneath ice sheets we find that chemical erosion in ice free areas at 18 ka was only slightly greater than today this result arises because the amount of land covered by ice sheets is roughly compensated for by exposed shelf areas and because there is little difference in global runoff the small 20 increase in the global chemical erosion rate during glacial conditions is due to exposure on the shelves of a relatively high proportion of carbonates which weather faster than average data on glacial interglacial movements of the calcite compensation depth ccd are inconclusive but seem to indicate little change whereas even a 20 increase in the riverine bicarbonate flux should cause an observable deepening if the ccd did not indeed change then our predicted increase in the bicarbonate flux from land during glaciations would have to be accommodated by other means such as increased carbonate productivity about half of the observed decrease in atmospheric pco2 at 18 ka could be explained if increased silicate chemical erosion accompanied increased total chemical erosion in ice free areas consideration of the maximum possible effect of meltwater at ice margins leads to an 80 increase in the global chemical erosion rate at 18 ka such an increase would lead to a larger and faster drop in atmospheric pco2 but also to an excessive deepening of the global ccd this scenario seems unrealistic our results are contrary to interpretations of a much higher silicate chemical erosion rate during glaciations based on recently published records of quaternary marine sr isotopic ratios therefore if these records are indeed globally representative and entirely due to increased silicate chemical erosion as opposed to changes in source areas or hydrothermal inputs then other factors such as a shift in the global weathering regime which we do not explicitly consider here may be involved sensitivity tests show that considering spatial heterogeneities in lithology and runoff leads to lower predictions of global chemical erosion rates than what one would obtain by considering only global averages in a non spatially resolved calculation

rapid topographic change measured by high resolution satellite radar at soufriere hills volcano montserrat 2008 2010 high resolution satellite radar observations of erupting volcanoes can yield valuable information on rapidly changing deposits and geomorphology using the terrasar x tsx radar with a spatial resolution of about 2 m and a repeat interval of 11 days we show how a variety of techniques were used to record some of the eruptive history of the soufriere hills volcano montserrat between july 2008 and february 2010 after a 15 month pause in lava dome growth a vulcanian explosion occurred on 28 july 2008 from a vent that was hidden by dense cloud we were able to show the civil authorities using tsx difference images of surface roughness change that this explosion had not disrupted the dome sufficiently to warrant continuation of a previous precautionary evacuation change difference images also proved to be valuable in mapping new pyroclastic flow deposits the valley occupying block and ash component tended to increase backscatter and the marginal surge deposits to reduce it with the pattern reversing after the event due to erosion and deposition by comparing east and west looking images acquired 12 h apart the deposition of some individual pyroclastic flows can be inferred from change differences some of the narrow upper sections of valleys draining the volcano received many tens of metres of rockfall and pyroclastic flow deposits over periods of a few weeks by measuring the changing radar shadows cast by these valleys in tsx images the changing depth of infill by deposits could be estimated in addition to using the amplitude data from the radar images we also used their phase information within the insar technique to calculate the topography during a period of no surface activity this enabled areas of transient topography crucial for directing future flows to be captured

time averaged discharge rate of subaerial lava at kīlauea volcano hawai i measured from tandem x interferometry implications for magma supply and storage during 2011 2013 differencing digital elevation models dems derived from terrasar add on for digital elevation measurements tandem x synthetic aperture radar imagery provides a measurement of elevation change over time on the east rift zone ezr of k lauea volcano hawai i the effusion of lava causes changes in topography when these elevation changes are summed over the area of an active lava flow it is possible to quantify the volume of lava emplaced at the surface during the time spanned by the tandem x data a parameter that can be difficult to measure across the entirety of an 100 km2 lava flow field using ground based techniques or optical remote sensing data based on the differences between multiple tandem x derived dems collected days to weeks apart the mean dense rock equivalent time averaged discharge rate of lava at k lauea between mid 2011 and mid 2013 was approximately 2 m3 s which is about half the long term average rate over the course of k lauea s 1983 present erz eruption this result implies that there was an increase in the proportion of lava stored versus erupted a decrease in the rate of magma supply to the volcano or some combination of both during this time period in addition to constraining the time averaged discharge rate of lava and the rates of magma supply and storage topographic change maps derived from space based tandem x data provide insights into the four dimensional evolution of k lauea s erz lava flow field tandem x data are a valuable complement to other space air and ground based observations of eruptive activity at k lauea and offer great promise at locations around the world for aiding with monitoring not just volcanic eruptions but any hazardous activity that results in surface change including landslides floods earthquakes and other natural and anthropogenic processes

soluble ionic and oxygen isotopic compositions of a shallow firn profile baishui glacier no 1 southeastern tibetan plateau in the summer of 2004 a firn profile 18 3m long extending down to glacier ice was recovered in the accumulation area of the largest glacier baishui no 1 on yulong mountain the southernmost glacier covered area in mainland eurasia multivariate empirical orthogonal function eof and statistical correlation analyses of major ion data from the profile demonstrate that three distinct types of ionic material contribute to the chemical characteristics of firn in this monsoonal region material of marine origin which is transported by the indian southwest monsoon crustal materials which come from local sources and anthropogenic pollutants which are produced by industrial and agricultural activities in south asia although the influence of post depositional processes on the seasonal isotopic and soluble ionic compositions is significant dust layers in the firn profile are clearly visible due to the effects of meltwater percolation the dust layers generally coincide with latesummer snow surfaces we therefore use the dust layers combined with the seasonal variations of electrical conductivity ec ca and mg to establish a depth age scale for the firn profile the reconstructed net accumulation has a significant negative correlation with the temperature at lijiang whereas the correlation between the net accumulation and the precipitation amount at lijiang is weak although the do time series of the firn profile was modified significantly by meltwater percolation the correlation between annual mean do values and the indian southwest monsoon index wsi1 is significant this result suggests that do records from monsoon influenced temperate glaciers can provide a valuable record of past variations of the indian southwest monsoon

pyroclastic deposits of the november 13 1985 eruption of nevado del ruiz volcano colombia abstract the november 13 1985 eruption of nevado del ruiz produced a series of pyroclastic flows and surges that eroded channels on the surface of the summit glacier and generated lahars which descended down most of the rivers that drain the volcano the stratigraphy of the proximal pyroclastic deposits indicates that there were at least four episodes to the eruption episode i deposited an unusual surge consisting of small pieces of ice mixed with ash and exhibiting planar stratification ballistically emplaced fragments are also intercalated with this unit during episode ii at least two pyroclastic flows were erupted their deposits contain the most evolved pumice of the entire eruption sio2 content of matrix glass ranges between 74 5 and 74 9 episode iii is marked by the emplacement of a welded tuff with an average sio2 content of about 66 in the matrix glass the final episode iv was characterized by the development of a high altitude eruption column and the emplacement of several nonwelded pyroclastic flows banded pumice are common in the pyroclastic flow as well as in the pumice fall deposits co existing dark and light pumice bands differ in sio2 content by 3 5 and in general are similar to the composition of the welded pumice from episode iii the compositional zonation of the pyroclastic deposits from episode i to iv suggests that a nearsurface compositionally stratified portion of the magma body was tapped during episode ii during episodes iii and iv the main body of magma was involved although the coexistence of the compositionally distinct pumice clasts at similar stratigraphic levels argues for mixing of magma from different levels in the chamber during the eruptive process

combination of srtm3 and repeat aster data for deriving alpine glacier flow velocities in the bhutan himalaya abstract the present study evaluates the fusion of dems from the advanced spaceborne thermal emission and reflection radiometer aster instrument and the shuttle radar topography mission srtm the study area consists of high elevation glaciers draining through the rough topography of the bhutan himalayas it turns out that the aster derived and srtm3 dems have similar accuracy over the study area but the srtm3 dem contains less gross errors however for rough topography large sections of the srtm3 dem contain no data we therefore compile a combined srtm3 aster dem from this final composite master dem we produce repeat aster orthoimages from which we evaluate the dem quality and derive glacier surface velocities through image matching the glacier tongues north of the himalayan main ridge which enter the tibet plateau show maximum surface velocities in the order of 100 200 m year 1 in contrast the ice within the glacier tongues south of the main ridge flows with a few tens of meters per year these findings have a number of implications among others for glacier dynamics glacier response to climate change glacier lake development or glacial erosion the study indicates that space based remote sensing can provide new insights into the magnitude of selected surface processes and feedback mechanisms that govern mountain geodynamics

the impact of misregistration on srtm and dem image differences abstract image differences between shuttle radar topography mission srtm data and other digital elevation models dems are often performed for either accuracy assessment or for estimating vegetation height across the landscape it has been widely assumed that the effect of sub pixel misregistration between the two models on resultant image differences is negligible yet this has not previously been tested in detail the aim of this study was to determine the impact that various levels of misregistration have on image differences between srtm and dems first very accurate image co registration was performed at two study sites between higher resolution dems and srtm data and then image differences srtm dem were performed after various levels of misregistration were systematically introduced into the srtm data it was found that 1 misregistration caused an erroneous and dominant correlation between elevation difference and aspect across the landscape 2 the direction of the misregistration defined the direction of this erroneous and systematic elevation difference 3 for sub pixel misregistration the error due solely to misregistration was greater than or equal to the true difference between the two models for substantial proportions of the landscape e g greater than 33 of the area for a half pixel misregistration and 4 the strength of the erroneous relationship with aspect was enhanced by steeper terrain spatial comparisons of dems were found to be sensitive to even sub pixel misregistration between the two models which resulted in a strong erroneous correlation with aspect this misregistration induced correlation with aspect is not likely specific to srtm data only we expect it to be a generic relationship present in any dem image difference analysis

the emplacement of the active lava flow at sinabung volcano sumatra indonesia documented by structure from motion photogrammetry abstract an effusive eruption at sinabung volcano in indonesia began in december 2013 we use structure from motion sfm photogrammetric techniques to create digital elevation models dems of the active lava flow we build dems from photographs taken during two separate time periods and from two separate low cost handheld cameras and compare them with a pre eruption dem to assess the quality and accuracy of photogrammetric dems created using different cameras calculate flow volume and long term average effusion rate and document changes in flow morphology on september 22nd 2014 the lava flow was 2 9 km long and had a volume of 1 03 0 14 108 m3 leading to an estimated time averaged discharge rate of 4 8 0 6 m3 s 1 differencing the photogrammetric dems shows that during the two week field campaign topographic changes of the flow occurred in zones along the flow front and on the upper flank a finding supported by relatively high temperatures in corresponding thermal images the deformation can be explained by active advance at the flow front and development of instabilities and collapse on the upper flanks large pyroclastic density currents associated with gravitational collapse of upper flank instabilities in october 2014 and june 2015 were caused by lava growing over ridges that had initially confined the flow to a pre existing channel this work demonstrates the ability of sfm photogrammetry to measure or identify the lava flow volume time averaged discharge rate flow emplacement rate and style as well as the development of gravitational instabilities our results show the potential of sfm photogrammetry as a cost and time effective method of repeatedly measuring active volcanic features and monitoring hazards at sinabung and during similar eruptions

a magmatic hydrothermal transition in arkaroola northern flinders ranges south australia from diopside titanite pegmatites to hematite quartz growth a set of palaeozoic diopside titanite veins are present in mesoproterozoic metagranites and metasediments that constitute the basement mt painter inlier of the adelaide fold belt south aus tralia these massive veins up to 1 m of pegmatitic nature contain large crystals of diopside lree y enriched titanite up to 40 cm in length and minor amounts of quartz they can be used to trace the sys tem s development from a high temperature magmatic stage through to a massive hydrothermal event the pegmatitic origin of these veins is evident from a complex fluid melt inclusion assemblage consisting of a highly saline inhomogeneous fluid and relicts of melt immiscibility of melt and heterogeneous highly saline fluids exceeding 61 eq mass nacl is preserved in primary inclusions in diopside and secondary inclusions in titanite indicating relatively shallow conditions of formation 510 20 c and 130 10 mpa graphic intergrowth of diopside and albite occurs at the contact with granitic pegmatites the system evolved into hydrothermal conditions which can be deduced from a later population of only fluid inclusions homogeneous and less saline 40 eq mass nacl trapped around 350 20 c and 80 10 mpa during quartz crystallization the conditions moved across the halite liquidus resulting in a heterogeneous mixture of brine and halite crystals which were trapped at 200 20 c and 50 10 mpa brecciation and a palaeo geother mal system overprinted the pegmatitic veins with an epithermal hematite quartz assemblage and lesser amounts of bladed calcite and fluorite in an intermit tently boiling hydrothermal system of fairly pure h2o at 100 140 c and 1 5 mpa remobilization of lrees and y from titanite and or the granitic host rock is evidenced by precipitation of apatite allanite and wakefieldite in an intermediate stage occasional incorporation of radioactive elements or minerals presumably u rich in the fluorite is responsible for radiolysis of h2 ot o h 2

hydrology of debris covered glaciers in high mountain asia abstract the hydrological characteristics of debris covered glaciers are known to be fundamentally different from those of clean ice glaciers even within the same climatological geological and geomorphological setting understanding how these characteristics influence the timing and magnitude of meltwater discharge is particularly important for regions where downstream communities rely on this resource for sanitation irrigation and hydropower such as high mountain asia the hydrology of debris covered glaciers is complex rugged surface topographies typically route meltwater through compound supraglacial englacial systems involving both channels and ponds as well as pathways that remain unknown low gradient tongues that extend several kilometres retard water conveyance and promote englacial storage englacial conduits are frequently abandoned and reactivated as water supply changes new lines of permeability are exploited and drainage is captured due to high rates of surface and subsurface change seasonal influences such as the monsoon are superimposed on these distinctive characteristics reorganising surface and subsurface drainage rapidly from one season to the next recent advances in understanding have mostly come from studies aimed at quantifying and describing supraglacial processes little is known about the subsurface hydrology particularly the nature or even existence of subglacial drainage in this review we consider in turn the supraglacial englacial subglacial and proglacial hydrological domains of debris covered glaciers in high mountain asia we summarise different lines of evidence to establish the current state of knowledge and in doing so identify major knowledge gaps finally we use this information to suggest six themes for future hydrological research at high mountain asian debris covered glaciers in order to make timely long term predictions of changes in the water they supply

volumetric change quantification of the 2010 merapi eruption using tandem x insar abstract accurate and up to date information on the time varying topography of active volcanoes is crucial for assessing material flows through these volcanic systems and along their surfaces as dome building volcanoes can change on meter scale within short time intervals in active phases conventionally used repeat pass sar interferometry insar often fails due to decorrelation effects while other methods to measure topography like aerial photogrammetry or lidar depend on the availability of the local infrastructure and on good weather conditions here we show the potential of the spaceborne earth observation mission tandem x to monitor topographic changes at active dome building volcanoes in this innovative satellite mission two nearly identical satellites fly in a close formation taking radar images of the earth s surface at the same time in bistatic mode this opens the possibility to generate digital elevation models dems of volcanoes analyzing a series of repeated dems enables assessment of volume changes caused by lava dome activity we apply this method to merapi in indonesia by analyzing the volume changes during the hazardous 2010 eruption during this eruption the old lava dome collapsed and a new lava dome was extruded which collapsed again within twelve days we show three dems derived from bistatic tandem x insar in descending orbit taken before and after the eruption we found a mean volume change of 19 10 6 m 3 in the summit area the two estimates differ by 0 4 10 6 m 3 which is 2 of the average dome volume change the tandem x based results are about 25 lower than reference data which can be explained by the shadow masks that were introduced to exclude geometrically decorrelated areas resulting in conservative volume change estimates

application of self organizing map and srtm data to characterize yardangs in the lut desert iran abstract yardangs an exclusive landform due to intensive wind erosion cover a large area in the hyper arid lut desert of iran this paper presents a new approach using self organizing map som as unsupervised algorithm of artificial neural networks for analysis and characterization of yardangs nowadays the shuttle radar topography mission srtm with 3 arc sec data approximately 90 m resolution and nearly world wide coverage provides uniform good quality data the srtm 3 arc sec data were re projected to a 90 m utm grid bivariate quadratic surfaces with moving window size of 5 5 were fitted to this dem the first derivative slope steepness and the second derivatives minimum maximum curvature and cross sectional curvatures were calculated as geomorphometric parameters used as input to the soms 42 soms with different learning parameter settings e g initial and final radius number of iterations and the effect of random initial weights on average quantization error were investigated a som with a low average quantization error 0 1040 was used for further analysis feature space analysis morphometric signatures three dimensional inspection auxiliary data like landsat etm and high resolution satellite imagery from quickbird facilitated the assignment of semantic meaning to the output classes in terms of geomorphometric features results are provided in a geographic information system as thematic maps of landform entities based on form and slope e g yardangs ridge corridors valley or planar areas the results showed that all yardangs and corridors were clearly recognized and classified by this method when their width was larger than the dem resolution but became unrecognizable if their width is much smaller than the grid resolution the identified yardangs and corridors are aligned nnw sse parallel to the prevailing direction of the strong local 120 days wind and cover about 31 and 42 of the study area respectively the results demonstrate that som is a very efficient tool for analyzing aeolian landforms in hyper arid environments that provides very useful information for terrain feature analysis in remote regions

high resolution tandem x dem an accurate method to estimate lava flow volumes at nyamulagira volcano d r congo nyamulagira and nyiragongo are two of the most active volcanoes in africa but their eruptive histories are poorly known assessing lava flow volumes in the region remains difficult as field surveys are often impossible and available digital elevation models dems do not have adequate spatial or temporal resolutions we therefore use terrasar x add on for digital elevation measurement tandem x interferometry to produce a series of 0 15 arc sec 5 m dems from between 2011 and 2012 over these volcanoes tandem x dems have an absolute vertical accuracy of 1 6 m resulting from the comparison of elevation with gps measurements acquired around nyiragongo the difference between tandem x derived dems from before and after the 2011 2012 eruption of nyamulagira provides an accurate thickness map of the lava flow emplaced during that activity values range from 3 m along the margins to 35 m in the middle with a mean of 12 7 m the erupted volume is 305 2 36 0 106 m3 height errors on thickness depend on the land covered by the flow and range from 0 4 m in old lavas to 5 5 m in dense vegetation we also reevaluate the volume of historical eruptions at nyamulagira since 2001 from the difference between tandem x and srtm 1 arc sec dems and compare them to previous work planimetric methods used in literature are consistent with our results for short duration eruptions but largely underestimate the volume of the long lived 2011 2012 eruption our new estimates of erupted volumes suggest that the mean eruption rate and the magma supply rate were relatively constant at nyamulagira during 2001 2012 respectively 23 1 m3 s 1 and 0 9 m3 s 1

the isotopic record at an alpine glacier and its implications for local climatic changes and isotopic homogenization processes stratigraphic variations of oxygen isotopes in the snow which accumulates during the winter at the norwegian glacier austre okstindbreen are not entirely eliminated after 1 2 months of ablation in the following summer the relationship between regional temperature changes and 18 o values in the snowpack is affected by many natural factors but 1989 90 winter air temperatures were reflected in the snow which remained on austre okstindbreen at 1350 m a s l in july 1990 there were many variations of 18 o values in the 4 1 m of snow above the 1989 summer surface but variations in the underlying firn were relatively small meltwater percolation modifies the initial variations of 18 o values in the snowpack at a site below the mean equilibrium line altitude on austre okstindbreen increased isotopic homogenization within a 10 day period in july accompanied an increase of the mean 18 o value although the isotopic record at a temperate glacier is likely to be influenced by more factors than is that at polar glaciers it can provide an estimate of the approximate trend of local temperature variations

the sensitivity of a volcanic flow model to digital elevation model accuracy experiments with digitised map contours and interferometric sar at ruapehu and taranaki volcanoes new zealand abstract a growing trend in the field of volcanic hazard assessment is the use of computer models of a variety of flows to predict potential areas of devastation these can be compared against historic and geologic evidence of past events for model calibration or used to construct hazard zone maps for mitigation and planning purposes the accuracy of these computer models depends on two factors the nature and veracity of the flow model itself and the accuracy of the topographic data set over which it is run all digital elevation models dems contain innate errors the nature of these depends on the accuracy of the original measurements of the terrain and on the method used to build the dem in this paper we investigate the effect that these errors have on the performance of a volcanic flow model designed to delineate areas at risk from lahar inundation the model was run over two dems of southern ruapehu volcano derived from 1 digitised 1 50 000 topographic maps and 2 airborne c band synthetic aperture radar sar interferometry obtained using the nasa airsar system on steep slopes of 4 or more drainage channels are more likely to be incised deeply and flow paths predicted by the model are generally in agreement for both dems despite the differing nature of the source data over shallow slopes

lahars initiated by the 13 november 1985 eruption of nevado del ruiz colombia the eruption of nevado del ruiz in colombia on 13 november 1985 was accompanied by the formation of four lahars mud flows triggered by the melting of glacial ice near the summit of the volcano the lahars began as flows of water sand and gravel but they incorporated clay by eroding the soil along the steep valleys through which they passed the largest flow was a cohesive debris flow more than 45 m deep and moving at 12 ms 1 when it debouched from the canyon of the rio lagunilla 2 5 km from armero where it killed 25 000 people the continuing volcanic activity and abundant remaining glacial ice create an extremely high risk of future destructive flows

atmospheric co2 sink silicate weathering or carbonate weathering it is widely accepted that chemical weathering of ca silicate rocks could potentially control long term climate change by providing feedback interaction with atmospheric co2 drawdown by means of precipitation of carbonate and that in contrast weathering of carbonate rocks has not an equivalent impact because all of the co2 consumed in the weathering process is returned to the atmosphere by the comparatively rapid precipitation of carbonates in the oceans here it is shown that the rapid kinetics of carbonate dissolution and the importance of small amounts of carbonate minerals in controlling the dissolved inorganic c dic of silicate watersheds coupled with aquatic photosynthetic uptake of the weatheringrelated dic and burial of some of the resulting organic c suggest that the atmospheric co2 sink from carbonate weathering may previously have been underestimated by a factor of about 3 amounting to 0 477 pg c a this indicates that the contribution of silicate weathering to the atmospheric co2 sink may be only 6 while the other 94 is by carbonate weathering therefore the atmospheric co2 sink by carbonate weathering might be significant in controlling both the short term and long term climate changes this questions the traditional point of view that only chemical weathering of ca silicate rocks potentially controls long term climate change

lava flow mapping and volume calculations for the 2012 2013 tolbachik kamchatka fissure eruption using bistatic tandem x insar the bistatic acquisition mode of the german tandem x radar satellite mission provides a reliable source for measuring morphological changes associated with volcanic activity we present the use of this system to measure key lava flow parameters including thickness volume runout and flow extent by using two tandem x data pairs to generate digital elevation models dems prior to and immediately following the 2012 2013 eruption of tolbachik volcano kamchatka morphometric parameters and areal distribution of the new lava flow field are determined using a cell by cell elevation difference between the two dems a total flow volume of 0 53 0 07 km3 a mean flow thickness of 14 5 m and a modal thickness of 7 8 m are calculated we use these calculated flow parameters as input to a volume limited lava flow emplacement model model simulations are able to reproduce the sw portion of the 2012 2013 tolbachik lava flow using a 75 m shuttle radar topography mission srtm dem and the 15 m tandem x derived dem with goodness of fit measures of 56 3 and 59 6 respectively based on the jaccard similarity coefficient the flow simulation done using srtm data underestimates the observed 14 4 km flow runout by over 3 km while the simulation with tandem x data overestimates flow runout by about 1 5 km performance of the lava flow modeling algorithm is highly dependent on the modal lava thickness highlighting the importance of using tandem x dems to provide precise lava flow measurements in order to constrain input parameters for numerical modeling of lava flows

evaluation of geophysical mass flow models using the 2006 block and ash flows of merapi volcano java indonesia towards a short term hazard assessment tool abstract the dynamics and depositional processes associated with block and ash flows bafs are most commonly inferred to be a function of granular or inertial grain flow similar to debris flows and cold rock avalanches existing geophysical mass flow models are either based on frictional mohr coulomb behavior the titan2d model developed at the state university of new york at buffalo usa or another rheological law i e a constant retarding stress eventually adding some viscous and turbulent components the volcflow model developed at the laboratoire magmas et volcans clermont ferrand france the 2006 bafs of merapi present a rare opportunity to test these two well established models against a well constrained field example integration of high resolution field based data into numerical simulations allows the validity of these models to be tested and rapid quantification of best fit input parameters we first show that with the incorporation of spatially varying bed friction angles titan2d is capable of reproducing the paths runout distances areas covered and deposited volumes of the 2006 merapi flows over highly complex topography however some discrepancies with field data are noted and the velocity and travel time of the flows do not match entirely using a single free parameter a constant retarding stress simulations obtained with the volcflow model also reproduce the morphology and distribution of the natural deposits as well as the time of emplacement and velocities of the flows the results suggest that the performance of these models in simulating actual events is critically dependent on 1 the calibration of the model by using extensive field based data such as deposit distribution and processes of flow generation transport and deposition 2 the incorporation of a suitable numerical topographic dataset i e high resolution digital elevation model and 3 the choice of input parameters such as location and volume of the initial pile of material and source characteristics single or multiple dome collapse dome collapse duration and total volume of collapsed material sensitivity analyses and inundation maps based on the probability of impact were used to produce a suite of potentially inundated areas from future gravitational dome collapse events affecting the gendol valley and adjacent areas on the southern flank of the volcano our results provide the basis for defining hazard zonations of key areas at risk from bafs which will be generated during future comparable eruptions at merapi

comparison of stereo extracted dtm from different high resolution sensors spot 5 eros a ikonos ii and quickbird digital elevation models dems extracted from high resolution stereo images spot 5 eros a ikonos ii and quickbird using a three dimensional multisensor physical model developed at the canada centre for remote sensing natural resources canada were evaluated in a first step the photogrammetric bundle adjustment was setup for the stereo images with few accurate ground control points in a second step dems were generated using an area based multiscale image matching method and then compared to 0 2 m accurate light detection and ranging lidar elevation data elevation linear errors with 68 confidence level le68 of 6 5 20 6 4 and 6 7 m were achieved for spot eros ikonos and quickbird respectively the poor results for eros are mainly due to its asynchronous low orbit which generated large geometric and radiometric differences however when such differences were not large le68 of 10 m four pixels was achieved since the spot ikonos and quickbird dems were in fact digital surface models where the height of land covers was included elevation accuracy was performed only on bare surfaces soils and lakes where there was no difference between the stereo extracted elevations and the lidar data le68 of 2 2 1 5 and 1 2 m were then obtained for spot ikonos and quickbird respectively when compared to sensor resolution multidate across track spot with a smaller base to height b h ratio of 0 77 achieved three to four times better results than same date in track ikonos and quickbird with b h of around 1 0 5 pixels versus 1 5 or 2 pixels

spatial and temporal variations of oxygen isotopes in snowpacks and glacial runoff in different types of glacial area in western china in order to improve understanding of spatial and temporal variations of stable isotopes in atmospheric precipitation snow cover and glacier meltwater in different regions of china samples were collected for isotopic analysis in four areas yulong mountain yunnan himalaya temperate glacier area samdain kangsang mountain nyainqentanglha shan subpolar glacier area the headwater area of the urumqi river tien shan subpolar glacier area and muztag mountain pamirs polar glacier area sampling was undertaken in both summer and winter between 2000 and 2003 the d 18 o values show a temperature altitude effect in new winter snow on yulong mountain reflecting the condensation and fractionation processes associated with the winter monsoon but a different more complex pattern in residual snow deposited during the summer monsoon this old snow is influenced by the precipitation amount effect solar radiation and evaporation and the water content of the snowpack the summer precipitation at samdain kangsang mountain is associated with the summer monsoon there is a marked precipitation amount effect during the long passage of the southwest india monsoon from the distant moisture source to samdain kangsang mountain and the summer precipitation is strongly depleted of the heavy isotope above 6000 m the high radiation flux causes much evaporation from the snow surface the associated 18 o enrichment of the snow is reflected in a reverse altitude effect the d 18 o values in the summer snowpack of the tien shan and muztag mountain decrease with increasing altitude and decreasing air temperature indicating a temperature altitude effect post depositional processes cause isotopic changes during the transformation of snow firn ice to meltwater the effects are much stronger at temperate than at polar glaciers moreover changes in the isotopic signal at both temperate and polar glaciers can result from evaporation sublimation ablation and drifting

the new remote sensing derived swiss glacier inventory ii first results complete swiss glacier inventories are available for 1850 reconstructed and 1973 from aerial photography connected to the global land ice measurements from space project a new swiss glacier inventory for approximately the year 2000 sgi 2000 is compiled mainly based on satellite imagery the developed and applied remotesensing and geographical information system gis methods are described in part i of the contribution in part ii the inventory design first result analyses and comparisons with former glacial conditions are presented as basic entries sgi 2000 contains the individual glacier identification planimetric glacier boundaries as derived from image analysis digitized central flowlines and polygonal glacier basin maps all other parameters are automatically deduced from the above entries and a digital elevation model within a gis here we analyze a set of small bernese and valais glaciers of area 2 these glaciers lost about 21 of area from 1973 to 1998 in addition to about 80 during 1850 1973 both with respect to the 1973 area in order to track the latest trend in more detail anintermediate glacier condition has been compiled from satellite imagery of 1985 this analysis gave an increasing speed of area loss 19 for 1985 98

tandem x time series analysis reveals lava flow volume and effusion rates of the 2012 2013 tolbachik kamchatka fissure eruption assessing eruption volumes is one of the major challenges in volcano research but provides valuable insights into the dynamics of an eruption and the associated hazard one way to estimate this important parameter is the generation and differencing of digital elevation models dems acquired before during and after an eruption the satellite mission tandem x enables generation of time series of dems using synthetic aperture radar satellite imagery we use these data to study the 2012 2013 eruption of tolbachik in kamchatka we developed a processing scheme for generation of 18 dems from tandem x imagery that relies on the generation of a preeruption dem which is used to process the syneruption and posteruption data pairs differencing each dem with the preeruption dem enables mapping the lava flows and measuring lava flow volume over time and to estimate lava extrusion rates we find a final lava flow volume of 0 53 km3 covering an area of 36 km2 by the end of the eruption an uncertainty analysis is performed while analyzing the dem differences in areas where no topographic change is expected leading to an error of 0 01 km3 for the final lava flow volume the lava effusion was with 247 92 m3 s very high in the first days of the eruption and rapidly decayed toward its end while many basaltic eruptions follow an exponentially decaying flow model the extrusion rates at tolbachik are more compatible with a 1 t model this special characteristic might be useful to gain further insight into the eruption process at tolbachik

temperature driven meltwater production and hydrochemical variations at a glaciated alpine karst aquifer implication for the atmospheric co2 sink under global warming about two hydrological years of continuous data of discharge temperature electrical conductivity and ph have been recorded at the glarey spring in the tsanfleuron glaciated karst area in the swiss alps to understand how glaciated karst aquifer systems respond hydrochemically to diurnal and seasonal recharge variations and how calcite dissolution by glacial meltwater contributes to the atmospheric co2 sink a thermodynamic model was used to link the continuous data to monthly water quality data allowing the calculation of co2 partial pressures and calcite saturation indexes the results show diurnal and seasonal hydrochemical variations controlled chiefly by air temperature the latter influencing karst aquifer recharge by ice and snowmelt karst process related atmospheric co2 sinks were more than four times higher in the melting season than those in the freezing season this finding has implication for understanding the atmospheric co2 sink in glaciated carbonate rock terrains the carbon sink will increase with increasing runoff caused by global warming i e carbonate weathering provides a negative feedback for anthropogenic co2 release however this is a transient regulation effect that is most efficient when glacial meltwater production is highest which in turn depends on the future climatic evolution

applying dem srtm for reconstructing a late quaternary paleodrainage in amazonia abstract remote sensing is a particularly invaluable tool that has helped the detection of paleomorphologies produced by river dislocation in a variety of landscapes which has contributed in reconstructing the geological evolution of many fluvial systems this technique might provide useful information to discuss the evolution of large fluvial systems in special those located in areas of difficult access where the acquisition of field data is difficult application of remote sensing for paleodrainage characterization in densely vegetated tropical areas is scarce in the literature this work records processing of the digital elevation model dem derived from the shuttle radar topography mission srtm which succeeded in revealing an ancient drainage complex of the madeira river one of the main amazonas tributaries where other remote sensing products failed the detection analysis of this paleodrainage and of its modern counterpart within the geological framework available for this region leads to propose that activity along pre existent faults during the latest quaternary would have promoted the southeastward dislocation of a nearly 200 km long segment of the madeira river during this process an impressive paleodrainage network was left behind which was only able to be detected using the dem srtm application of this technique might be of great help to the detection of paleodrainage morphologies in densely vegetated areas similar to the amazonas lowland the dynamics of channel migration in this and many other large scale tropical river systems might benefit from the investigation based on data derived from dem srtm

a groundwater conceptual model and karst related carbon sink for a glacierized alpine karst aquifer southwestern china summary in the jade dragon snow mountain jdsm region yunnan province sw china an extensive hydrochemical and stable isotopic study of a glacierized alpine karst aquifer was conducted during the period 2011 2014 the objectives of the study were first to establish a conceptual hydrogeological model of the karst groundwater system second to estimate the proportion of extra glacier melt water infiltrating the karst aquifer that is being induced by the regional climate warming third to calculate the karst related flux of carbon into the karst aquifer knowledge of the local hydrogeological background from previous work was the starting point of the hydrochemical and stable isotopic study some representative spring waters and recharge waters i e glacier melt water and rainwater were investigated both spatially and temporally by hydrochemical and isotopic techniques including analysis of major and some minor ions and o and h stable isotopes a conceptual hydrogeological model of a fracture diffuse flow karst groundwater aquifer was proposed the proportion of glacier melt water infiltrating into the karst aquifer was estimated by using the karst spring as a natural pluviometer and with stable isotope analysis results show that 1 the jdsm karst aquifer is a diffuse flow system 2 it has a number of discharge areas and the jinsha river is the karst drainage base level 3 the proportion of the glacier melt water penetrating the karst aquifer is 29 and 4 the karst related carbon sink is 26 67 3 44 t km 2 a 1 as co 2 which is lower than that in non glacierized karst aquifers but over ten times larger than the carbon sink flux from silicate weathering in non karst areas showing the control of both climate and lithology on the rock weathering related carbon sink and the significance of carbonate weathering in the global carbon cycle

high resolution dem generation from spaceborne and terrestrial remote sensing data for improved volcano hazard assessment a case study at nevado del ruiz colombia abstract volcanoes with rugged terrain remain a challenging target for generating high resolution digital elevation models dems especially in tropical areas with frequent cloud cover using nevado del ruiz volcano as an example we combined dems from the tandem x tdx satellite mission terrestrial radar interferometry tri and structure from motion sfm to generate a new dem with 10 m spatial resolution this is the first study combining satellite radar ground based radar photography and freely available global dems to generate a high resolution dem without data gaps tdx data from ascending and descending orbits were combined to generate the base dem instead of using a raster format to fuse dems generated from different data sets with different resolutions we developed a methodology based on 3 d point clouds 1 re georeference the 5 m tri and 1 m sfm dems to the 10 m tdx dem using the iterative closest point icp algorithm to minimize the horizontal and vertical discrepancy between dems then 2 merge the multiple point clouds to generate a final dem without data gaps using an adaptive algorithm that uses two search distances to smooth the transition at the edges of different data sets we assess the new 10 m dem by comparing simulated inundation zones obtained with two volcano flow models laharz for lahars and volcflow for pyroclastic flows and find significant differences with respect to the 30 m srtm dem our laharz simulation over the new dem shows a longer lahar run out distance for pyroclastic flows the volcflow simulation over the new dem produces highly channelized flows over the steep portions of a river channel and gives a larger extent of thicker deposits compared to those obtained with the 30 m srtm dem quantitative and qualitative geomorphic analysis suggests that up to date dems with high spatial resolution 10 m or even better need to be generated to improve volcano hazard assessment for active volcanoes

tracing effects of decalcification on solute sources in a shallow groundwater aquifer nw germany summary 87 sr values and ca sr ratios were employed to quantify solute inputs from atmospheric and lithogenic sources to a catchment in nw germany the aquifer consists primarily of unconsolidated pleistocene eolian and fluviatile deposits predominated by 90 quartz sand accessory minerals include feldspar glauconite and mica as well as disperse calcium carbonate in deeper levels decalcification of near surface sediment induces groundwater ph values up to 4 4 that lead to enhanced silicate weathering consequently low mineralized ca na cl and ca cl groundwater types are common in shallow depths while in deeper located calcareous sediment ca hco 3 type groundwater prevails 87 sr values and ca sr ratios of the dissolved pool range from 7 3 to 2 6 and 88 to 493 respectively positive 87 sr values and low ca sr ratios indicate enhanced feldspar dissolution in shallow depths of less than 20 m below soil surface bss while equilibrium with calcite governs negative 87 sr values and elevated ca sr ratios in deep groundwater 30 m bss both positive and negative 87 sr values are evolved in intermediate depths 20 30 m bss for groundwater that is undersaturated with respect to calcite atmospheric supplies range from 4 to 20 while feldspar weathering accounts for 8 26 and calcium carbonate for 62 90 of dissolved sr 2 in contrast more than 95 of sr 2 is derived by calcium carbonate and less than 5 by feldspar dissolution in ca hco 3 type groundwater the surprisingly high content of carbonate derived sr 2 in groundwater of the decalcified portion of the aquifer may account for considerable contributions from ca containing fertilizers complementary tritium analyses show that equilibrium with calcite is restricted to old groundwater sources

evaluation of aster and srtm dem data for lahar modeling a case study on lahars from popocatepetl volcano mexico abstract lahars are among the most serious and far reaching volcanic hazards in regions with potential interactions of lahars with populated areas and human structures the assessment of the related hazards is crucial for undertaking appropriate mitigating actions and reduce the associated risks modeling of lahars has become an important tool in such assessments in particular where the geologic record of past events is insufficient mass flow modeling strongly relies on digital terrain data availability of digital elevation models dems however is often limited and thus an obstacle to lahar modeling remote sensing technology has now opened new perspectives in generating dems in this study we evaluate the feasibility of dems derived from the advanced spaceborne thermal emission and reflection radiometer aster and the shuttle radar topography mission srtm for lahar modeling on popocatepetl volcano mexico two gis based models are used for lahar modeling laharz and a flow routing based debris flow model modified single flow direction model msf both predicting areas potentially affected by lahars results of the lahar modeling show that both the aster and srtm dems are basically suitable for use with laharz and msf flow path prediction is found to be more reliable with srtm data though with a coarser spatial resolution errors of the aster dem affecting the prediction of flow paths due to the sensor geometry are associated with deeply incised gorges with north facing slopes laharz is more sensitive to errors of the aster dem than the msf model lahar modeling with the aster dem results in a more finely spaced predicted inundation area but does not add any significant information in comparison with the srtm dem lahars at popocatepetl are modeled with volumes of 1 10 5 to 8 10 6 m 3 based on ice melt scenarios of the glaciers on top of the volcano and data on recent and historical lahar events as regards recently observed lahars the travel distance of lahars of corresponding volume modeled with laharz falls short by 2 to 4 km an important finding is that the travel distance of potential lahar events modeled with laharz may differ by about 2 km when using srtm or aster data because of varying lateral flow volume distribution as a consequence verification and sensitivity analysis of the dem is fundamental to deriving hazard maps from predicted modeled inundation areas because of the global coverage of this type of remote sensing data the conclusion that both srtm and aster derived dems are feasible for lahar modeling opens a wide field of application in volcanic hazards studies

concentrations and exports of solutes from surface runoff in houzhai karst basin southwest china chemical concentrations and export rates from surface water were analyzed in houzhai karst basin hkb area 80 65 km 2 in total southwest china for the past two decades from 1986 to 2007 surface water chemistry was dominated by ions of calcium ca2 magnesium mg2 bicarbonate hco3 and sulfate so42 which together made up 96 by weight of the total dissolved solids measured in this study seasonal variability of chemical export rates was positively correlated with surface runoff discharge with the concentrations generally diluting at high discharge from 1986 to 2007 as a result of the responses of karst weathering to climatic factors the concentrations of ca2 mg2 hco3 and so42 slowly increased in surface water by contrast changes in the concentrations of sodium na potassium k and chloride cl showed a slowly decreasing pattern we also found that the annual dissolved inorganic carbon dic flux ranged from 10 1 to 34 1 g c m 2 yr 1 with an average value of 242 g c m 2 yr 1 rainfall had the most important influence on dic flux although water ph may greatly affect the proportions of the three fractions co2 hco3 co32 of dic high water temperature in the wet season may reduce the solubility of co2 in water and consequently affect dic export rate but this effect is much smaller than that of rainfall based on the chemical mass balance in surface water our results indicate that high concentrations of so42 by the large gypsum caso4 center dot 2h 2 o dissolution offset some anions such as hco3 in karst water which can partly explain why carbon uptake is often overestimated by the empirical model using concentrations of hco3 in this karst water it is concluded that the fluvial flux of dic from karst water is important to the regional or national carbon budgets c 2012 elsevier b v all rights reserved

parallel adaptive numerical simulation of dry avalanches over natural terrain high fidelity computational simulation can be an invaluable tool in planning strategies for hazard risk mitigation the accuracy and reliability of the predictions are crucial elements of these tools being successful we present here a new simulation tool for dry granular avalanches using several new techniques to create a highly accurate tool with a combination of good models and numerical methodologies highlights of our methodology are the use of a depth averaged model of the conservation laws and an adaptive grid godunov solver to solve the resulting equations the software is designed to run on distributed memory supercomputers and make use of digital elevation data dynamically i e refine the grid and input data to finer resolutions to better capture flow features as the flow evolves our simulations are validated using quantitative and qualitative comparisons to tabletop experiments and data from field observations our software is freely available and can be used on a range of hardware from inexpensive desktop computers to the largest supercomputers

crustal solute fluxes and transient carbon dioxide drawdown in the scottbreen basin svalbard in 2002 summary solute fluxes and transient carbon dioxide drawdown in a small glacierized basin investigated on svalbard in 2002 are presented it was a sample year within a period of significant climate warming in the arctic discharge was recorded in the scottbreen basin 10 1 km 2 bellsund fjord between july 8 and september 10 2002 specific runoff for this period was 0 784 m 22 more than the mean for 1986 2001 the runoff for all of 2002 i e the hydrologic year was estimated by comparison with bayelva the only glacial river with longer records on svalbard the specific runoff for 2002 was 1 228 m yielding crustal solute fluxes of 69 4 t km 2 yr 1 25 8 m 3 km 2 yr 1 this rate is the highest chemical denudation rate reported from glacierized basins on svalbard and it may be underestimated because higher solute fluxes at the beginning of the melt season were not taken into account crustal fluxes in the fall may also have been higher because it is probable that crustal ion concentrations were increasing after recording stopped in september the cation denudation rate was 1213 meq m 2 yr 1 and the mean annual crustal ion concentration derived from it amounted to 981 eq l 1 transient co 2 drawdown in 2002 was 5242 kg c km 2 yr 1 most of the carbon dioxide was removed in the summer ablation waters estimated co 2 drawdown in the fall being only 13 of the total comparison with crustal solute fluxes csf computed from specific conductivity in the 1980s and 1990s suggests that earlier fluxes may have been overestimated by around 19 comparing earlier data with the 2002 rates may confirm the influence of climate warming on increasing chemical denudation rates it was also found that a globally derived equation relating specific conductivity to concentrations of dissolved limestone in water gave estimates of the crustal solute fluxes that were only 1 1 less than those obtained via comprehensive chemical analyses of waters and ion partitioning procedures

deep source model for nevado del ruiz volcano colombia constrained by interferometric synthetic aperture radar observations nevado del ruiz is part of a large volcano complex in the northern andes of colombia interferometric synthetic aperture radar observations from the radarsat 2 satellite since 2011 show steady inflation of the volcano since 2012 at 3 4 cm yr the broad 20 km deformation pattern from both ascending and descending track data constrain source models for either point or spheroidal sources both located at 14 km beneath the surface mean elevation 4 2 km and 10 km sw of nevado del ruiz below nearby santa isabel volcano stress change computations for both sources in the context of a compressive regional stress indicate that dikes propagating from the source should become trapped in sills possibly leading to a more complex pathway to the surface and explaining the significant lateral separation of the source and nevado del ruiz volcano

rapid disintegration of alpine glaciers observed with satellite data analyses of multispectral satellite data indicate accelerated glacier decline around the globe since the 1980s by using digitized glacier outlines inferred from the 1973 inventory and landsat thematic mapper tm satellite data from 1985 to 1999 we obtained area changes of about 930 alpine glaciers the 18 area reduction as observed for the period 1985 to 1999 1 3 a corresponds to a seven times higher loss rate compared to the 1850 1973 decadal mean extrapolation of area change rates and cumulative mass balances to all alpine glaciers yields a corresponding volume loss of about 25 km since 1973 highly individual and non uniform changes in glacier geometry disintegration indicate a massive down wasting rather than a dynamic response to a changed climate our results imply stronger ongoing glacier retreat than assumed so far and a probable further enhancement of glacier disintegration by positive feedbacks

the co2 consumption potential during gray shale weathering insights from the evolution of carbon isotopes in the susquehanna shale hills critical zone observatory abstract shale covers about 25 of the land surface and is therefore an important rock type that consumes co 2 during weathering we evaluated the potential of gray shale to take up co 2 from the atmosphere by investigating the evolution of dissolved inorganic carbon dic concentrations and its carbon isotopic ratio 13 c dic along water flow paths in a well characterized critical zone observatory susquehanna shale hills catchment in this catchment chemical weathering in shallow soils is dominated by clay transformation as no carbonates are present and soil pore waters are characterized by low dic and ph in shallow soil porewaters the dic dominated by dissolved co 2 is in chemical and isotopic equilibrium with co 2 in the soil atmosphere where pco 2 varies seasonally to as high as 40 times that of the atmosphere the degradation of ancient organic matter is negligible in contributing to soil co 2 the chemistry of groundwater varies along different flowpaths as soil pore water recharges to the water table and then dissolves ankerite or secondary calcite under the valley floor weathering of carbonate leads to much higher concentrations of dic 2500 mol l and divalent cations ca 2 and mg 2 in groundwaters than soil waters the depth to the ankerite weathering front is hypothesized to be roughly coincident with the water table but it varies due to heterogeneities in the protolith composition groundwater chemistry therefore shows different saturation indices with respect to ankerite depending upon location along the valley the 13 c dic values of these groundwaters document mixing between the ankerite and soil co 2 the major element concentrations dic and 13 c dic in the first order stream incising the valley of the catchment are derived from groundwater and soil waters in proportions that vary both spatially and temporally the co 2 degassed slightly in the stream but little evidence of c isotopic equilibration with the atmosphere is observed due to the short length of the stream and short contact time with air the ankerite reaction front also lies close to the pyrite dissolution front pyrite oxidation in bedrock likely released sulfuric acid and played a minor role in the ankerite dissolution shifting groundwater 13 c dic slightly above the expected mixing values at the catchment scale the stream so 4 2 is also dominantly derived from wet deposition as stream has 34 s so4 values around 3 well within the range of acid deposition a mass balance calculation shows that silicate and ankerite dissolution of the rose hill shale at shale hills consumes co 2 at a rate of 44 and 42 48 mol m 2 ky 1 respectively while degradation of ancient organic matter releases co 2 at a rate of 1 3 mol m 2 ky 1 silicate dissolution at the shallow soils is facilitated by low ph and high soil pco 2 as ankerite dissolution and organic matter oxidation are shown to occur early during shale alteration co 2 consumption by shale weathering is thus limited by initiation of rock disintegration e g fractures and exposure of fresh surface area to infiltrating co 2 and o 2 rich water

high resolution digital elevation model from tri stereo pleiades 1 satellite imagery for lava flow volume estimates at fogo volcano resolving changes in topography through time using accurate high resolution digital elevation models dems is key to understanding active volcanic processes for the first time in a volcanic environment we utilize very high resolution tri stereo optical imagery acquired by the pleiades 1 satellite constellation and generate a 1 m resolution dem of fogo volcano cape verde the most active volcano in the eastern atlantic region point cloud density is increased by a factor of 6 5 compared to conventional stereo imagery and the number of 1 m2 pixels with no height measurements is reduced by 43 we use the dem to quantify topographic changes associated with the 2014 2015 eruption at fogo height differences between the posteruptive pleiades 1 dem and the preeruptive topography from tandem x give a lava flow volume of 45 83 0 02 106 m3 emplaced over an area of 4 8 km2 at a mean rate of 6 8 m3 s 1

volcflow capabilities and potential development for the simulation of lava flows volcflow is a finite difference eulerian code based on the depth averaged approach and developed for the simulation of isothermal geophysical flows its capability for reproducing lava flows is tested here for the first time the field example chosen is the 2010 lava flow of tungurahua volcano ecuador the emplacement of which is tracked by projecting thermal images onto a georeferenced digital topography results show that at least for this case study the isothermal approach of volcflow is able to simulate the velocity of the lava through time as well as the extent of the solidified lava however the good fit between the modelled and the natural flow may be explained by the short emplacement time c 20 h of a thick lava c 5 m which could limit the influence of cooling on the flow dynamics thus favouring the use of an isothermal rheology

anomalous alkaline rocks of soustov kola evidence of mantle derived metasomatic fluids affecting crustal materials the intrusive complexes of gremiakha vyrmes and soustov represent the two extremes of the early proterozoic alkaline plutons of kola predominantly composed of feldespathoidal syenites gremiakha vyrmes rocks zircon age 1 884 6 ma have trace element and isotope signatures 87sr 86srt 0 704 endt 3 1 3 compatible with an ultimate mantle origin soustov syenites zircon age 1 872 8 ma are totally different and show an acute crustal imprint they have sodaline and analcite instead of nepheline contain a plethora of ree hfse rich accessories and are characterised by elevated contents of f cl ree y th u zr hf nb ta sn be li rb tl pb and cs negative eu anomalies k rb 190 160 nd th 3 and nb ta 12 with extremely high 87sr 86srt 0 720 and at the same time relatively high endt 1 6 1 7 in this paper we explore the idea that the anomalous features of soustov syenites can be explained if we assume they are derived from a metasomatic agent initially an h2o co2 supercritical fluid released by alkaline mafic magmas that was profoundly contaminated during percolation through crustal materials as percolation advanced the bulk composition of the fluid solute changed from alkali halides and carbonates to a silica undersaturated alkaline melt when the fluid cooled to a temperature of 550 600 c it reached the point at which vapor and melt were no longer miscible and split into two components a vapour phase and a cl and f rich silica undersaturated silicate melt that crystallised to produce soustov syenites to study this process we have developed a numerical method for modelling the solute composition of the fluid during the infiltration metasomatism our results using the lree abundances and the sr and nd isotope composition of a gremiakha vyrmes pegmatite as the starting solute composition of the fluid and the mode and mineral trace element and isotope composition of a common kola gneiss as representative of percolated materials indicate that the fluid would have acquired a signature closely matching soustov s even in the case of nd isotopes if the gneiss age is 2 9 ga near its real age this model is still a mere working hypothesis that needs further refinements but may represent a reasonable explanation of the genesis of anomalous alkaline rocks with high 87sr 86srt and endt 0 either saturated or undersaturated which are difficult to understand in terms of magmatic fractionation contamination

combining satellite multispectral image data and a digital elevation model for mapping debris covered glaciers automated glacier mapping from satellite multispectral image data is hampered by debris cover on glacier surfaces supraglacial debris exhibits the same spectral properties as lateral and terminal moraines fluvioglacial deposits and bedrock outside the glacier margin and is thus not detectable by means of multispectral classification alone based on the observation of low slope angles for debris covered glacier tongues we developed a multisource method for mapping supraglacial debris the method combines the advantages of automated multispectral classification for clean glacier ice and vegetation with slope information derived from a digital elevation model dem neighbourhood analysis and change detection is applied for further improvement of the resulting glacier debris map a significant percentage of the processing can be done automatically in order to test the sensitivity of our method against different dem qualities it was also applied to a dem obtained from aster stereo data additionally we compared our multisource approach to an artificial neural network ann classification of debris using only multispectral data while the combination with an aster derived dem revealed promising results the ann classification without dem data does not

interaction of biotite amphibole gneiss with h2o co2 k na cl fluids at 550 mpa and 750 and 800 с experimental study and applications to dehydration and partial melting in the middle crust to constrain effects of chloride bearing h2o co2 fluids on complex natural assemblages during high grade metamorphism and anatexis we report the results of experiments on the interaction of biotite hornblende tonalitic gneiss from the sand river formation limpopo complex south africa with h2o co2 h2o co2 kcl h2o co2 nacl and h2o co2 k na cl fluids at 550mpa 750 and 8008c and varying chloride h2o co2 ratios with molar co2 co2 h2o 1 4 0 5 heating of solid cylinders of gneiss at both temperatures in the absence of a free fluid phase produced no changes in the gneiss phase assemblage the equimolar h2o co2 fluid at 7508q also did not significantly influence the phase assemblage addition of kcl to the fluid at 7508q resulted in formation of the clinopyroxene k feldspar ilmenite titanite assemblage after biotite hornblende and plagioclase orthopyroxene accompanied by amphibole appeared only at 8008c as a result of biotite breakdown in the presence of h2o co2 and low salinity h2o co2 kcl fluids increase in the kcl content in the fluid at 8008q resulted in the production of a clinopyroxenebearing assemblage increase of the nacl content stabilized amphibole in an assemblage with either orthopyroxene at low nacl concentrations or clinopyroxene nevertheless clinopyroxene albite is stable only at high salt concentrations comparison of the experimental results with the results of thermodynamic modeling using the gibbs free energy minimization method perple x software showed that mineral reactions and assemblages in the run products were governed by the activities of alkali components imposed by kcl and nacl in the h2o co2 fluids and decrease of the water activity served as an additional factor stabilizing anhydrous assemblages no melts formed at 7508c in the presence of the h2o co2 kcl fluids these fluids provoked melting only at 8008c with formation of rhyolitic melts with increasing kcl content of the fluid the melt composition changed to potassic rhyolitic with al2o3513 5 wt cao52 wt k2o na2o47 wt feo feo mgo 40 8 k2o na2o41 and moderate enrichment in cl 0 2 0 6 wt increasing nacl content caused melting at 7508q and shifted the melt composition towards trachytic and trachyandesitic compositions at both 750 and 8008q the experiments support a model for the formation of ferroan a type granite syenite complexes via crustal melting in the presence of h2o co2 salt fluids in extensional tectonic settings they demonstrate a possible link between a type granitoids and mid crustal dehydration zones in amphiboliteto granulite facies terrains and allow a new interpretation of mineral assemblages within these zones in terms of variations in fluid salinity

objective delineation of lahar inundation hazard zones a new method of delineating lahar hazard zones in valleys that head on volcano flanks provides a rapid objective reproducible alternative to traditional methods the rationale for the method derives from scaling analyses of generic lahar paths and statistical analyses of 27 lahar paths documented at nine volcanoes together these analyses yield semiempirical equations that predict inundated valley cross sectional areas a and planimetric areas b as functions of lahar volume v the predictive equations a 0 05v 2 3 and b 200v 2 3 provide all information necessary to calculate and plot in

numerical simulations of block and ash flows using the titan2d flow model examples from the 2006 eruption of merapi volcano java indonesia we present titan2d simulations of two well characterized block and ash flow baf events of the 2006 eruption of merapi java indonesia that affected the gendol valley on the volcano s southern flank and adjacent densely populated interfluve non valley areas 1 a single dome collapse event to the south that generated one of the smaller post june 14 flows and 2 a sustained multiple dome collapse event also directed to the south that produced the largest flows of the 2006 eruption emplaced in the afternoon of june 14 using spatially varying bed friction angles titan2d is capable of reproducing the paths velocities runout distance areas covered and deposited volumes of these flows over highly complex topography the model results provide the basis for estimating the areas and levels of hazards associated with bafs generated during relatively short as well as prolonged dome collapse periods and guidance during future eruptive crises at merapi

a review of terrestrial radar interferometry for measuring surface change in the geosciences this paper presents a review of the current state of the art in the use of terrestrial radar interferometry for the detection of surface changes related to mass movement different hardware types and acquisition concepts are described which use either real or synthetic aperture for radar image formation we present approaches for data processing procedures paying special attention to the separation of high resolution displacement information from atmospheric phase variations recent case studies are used to illustrate applications in terrestrial radar interferometry for change detection applications range from detection and quantification of very slow moving millimeters to centimeters per year displacements in rock walls from repeat monitoring to rapid processes resulting in fast displacements 50 m yr acquired during single measurement campaigns with durations of only a few hours fast and episodic acting processes such as rockfall and snow avalanches can be assessed qualitatively in the spatial domain by mapping decorrelation caused by those processes a concluding guide to best practice outlines the necessary preconditions that have to be fulfilled for successful application of the technique as well as in areas characterized by rapid decorrelation empirical data from a ku band sensor show the range of temporal decorrelation of different surfaces after more than two years for rock surfaces and after a few seconds to minutes in vegetated areas during windy conditions the examples show that the displacement field can be measured for landslides in dense grassland ice surfaces on flowing glaciers and snowpack creep copyright 2014 john wiley sons ltd

topographic mapping from interferometric synthetic aperture radar observations interferometric synthetic aperture radar observations provide a means for obtaining high resolution topographic terrain maps from data acquired simultaneously at two slightly displaced antennas calculation of the three dimensional coordinates of all the points in a radar image can be made from the combination of along track slant range and interferometer fringe measurements thus the result compensates for the layover exhibited by conventional radar maps and removes the false targets generated by multiple signal paths to a given object in the scene we have derived a topographic map of a portion of the san francisco bay area utilizing data that were recorded by a radar system mounted on a nasa cv990 aircraft and processed by a general purpose digital computer this map displays the height above sea level of a region approximately 11 km by 10 km in size sampled on an 11 m pixel grid uncertainties in the estimated height result from imprecise knowledge of the observational geometry radar bandwidth limitations and finite signal to noise ratios for our system each factor contributed approximately 3 4 m to a relative rms error of about 6 m additional global errors of the order of 10 m can result from inaccurate monitoring of aircraft attitude the statistical variation of the height measurements from the ocean portion of the map which we can presume to be quite flat is 2 10 m rms which is consistent with the theoretical estimate comparison of our results with u s geological survey contour maps indicates a high degree of correlation between the two sets of altitude data

hydrochemical and isotope characteristics of spring water and travertine in the baishuitai area sw china and their meaning for paleoenvironmental reconstruction a method of combining hydrochemical data logging and in situ titrating with measurement of stable carbon and oxygen isotopes was used to reveal the hydrochemical and isotopic characteristics in the baishuitai travertine scenic area of sw china it was found that the travertine forming springs have a very high concentration of calcium and bicarbonate and accordingly very high co2 partial pressures which are not likely to be produced by biological activity in soil alone further analysis of the stable carbon isotopes of the springs shows that the high pressure of co2 is mainly related to an endogenic co2 source that means the baishuitai travertine is endogenic in origin this is contrast to the commonly accepted saying that the travertine deposition in this study simply is a product of warm and humid conditions in a karst ecological environment rapid co2 degassing from the water is triggered by the much higher partial pressures in water than that of the surrounding air consequently as the waters flow downstream of the spring the ph increases the waters become supersaturated with respect to calcite and travertine is deposited the preferential release of 12co2 to the atmosphere results in a progressive increase of travertine 13c downstream this is concluded with a preliminary discussion of variation in travertine forming water temperatures according to differences in stable oxygen isotopic compositions of the travertine formed in different epochs at baishuitai it was found that the change in water temperature is as high as 13 c i e from 23 c at about 2500 years b p to 10 c at present this may mainly reflect that the effect of geothermal source on water temperature is decreasing the problems involved in paleoenvironmental reconstruction with endogene travertine are also discussed they are the impacts of dead carbon in radiocarbon dating and the enrichment in 13c of travertine by endogenic co2 and degassing of co2 from water which has to be considered in paleovegetation reconstruction when using 13c data of the endogene carbonate deposits

karst springs as natural pluviometers constraints on the isotopic composition of rainfall in the apennines of central italy abstract this paper describes an indirect method to calculate the isotopic composition of rainfall by using the isotopic composition of karst springs fed by waters circulating in the most important regional aquifer of central italy i e the mesozoic limestone sequence that forms the backbone of the apennines by using 18o and d data and the 18o and or d average gradient for elevation evaluated through the use of literature rainfall data and new measurements from a typical alpine valley in northern italy the altitude of precipitation of their parent water has been re calculated vertical descents of more than 2000 m from recharge to discharge have been assessed in some high flow rate cold springs in the morphologically steep adriatic sector of central italy a clear correlation between the vertical descents and more negative isotopic compositions at their relative emergence elevations is highlighted in contrast in the tyrrhenian sector lower karstic drops generally lower than 500 m correlate with less negative isotopic composition of recharge areas the 18o iso contour map of the recalculated parent rainfall in central italy is more detailed than any possible isotopic map of rainfall made using pluviometers unless large number of rainfall collectors were deployed on mountaintops the data also show that the isotopic composition of rainfall depends on the source of the storm water in particular precipitation is isotopically heavier when originating in the mediterranean sea and lighter when formed in the atlantic ocean consequently the collision between air masses with such a different isotopic signature results in a relatively small latitudinal fractionation effect the peninsular part of central italy is very narrow with several mountains and massifs more that 2000 m high and any latitudinal variation in the isotopic composition between rainfall sourced in the atlantic ocean and in the mediterranean sea is much lower than that due to the isotopic fractionation due to elevation

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

carbonate weathering related carbon sink fluxes under different land uses a case study from the shawan simulation test site puding southwest china abstract in the study of global climate change a major focus of research into the carbon cycle is to determine the fate of missing carbon sinks carbonate weathering related carbon sinks as a result of water carbonate co2 aquatic phototroph interactions may make a major contribution establishing optimal land uses which determine soil co2 concentrations and water supplies for carbonate dissolution may be a feasible and effective way to increase the sink potential elucidating both the hydrological and the hydrochemical behavior under different land uses is critical for rational planning of land use changes to increase the carbon sink given the complexity within natural karst catchments the shawan simulation test site was established at puding southwest china to simulate the influence of land uses with controlled carbonate test beds bare rock bare soil crop land grass land shrub land soil co2 concentrations hydrochemical parameters ph major ion concentrations and the spring artificial drain discharge were intensively measured from sept 1 2015 to aug 31 2016 to investigate the carbon and water responses to different land uses in different seasons in the vegetated land uses crop grass or shrub dic increased due to the increase of soil co2 resulting from stronger microbial activities and root respiration in summer and autumn growing seasons in the bare rock and soil cases there was also an increase in dic in summer and autumn due to decomposition of prior organic matter within soils and or rock pores the average dic concentration ranking high to low was grass land shrub land crop land bare soil bare rock soil co2 concentration was thus the dominant of dic concentration which is a key multiplier of carbon sink fluxes csf 0 5 dic rd where rd is depth of runoff dic is dic concentration and 0 5 because in carbonate dissolution only half of the hco3 is of atmospheric carbon origin however runoff depth ranked almost in reverse order i e from high to low bare rock bare soil crop land shrub land grass land the csf ranking from high to low was grass crop shrub bare rock bare soil a new parameter lcic land use change impact on csf is defined to compare the impacts of land use change on dic and rd and evaluate their combined effects on csf compared to bare rock the absolute values of lcic lcic s were 1 and csfs were larger for the three tanks with vegetation cover csf is smaller for bare soil lcic

temporal monitoring of subglacial volcanoes with tandem x application to the 2014 2015 eruption within the barðarbunga volcanic system iceland on august 29 2014 a lava eruption commenced in the holuhraun plain north east of the bar arbunga caldera in iceland the eruption ended on february 27 2015 thus lasting for a period of about 6 months during these months the magma chamber below the caldera gradually deflated feeding the eruption and causing the rare event of a slow caldera collapse in this scenario tandem x remote sensing data are of particular interest by producing medium high resolution and accurate elevation models of the caldera it is possible to evaluate volume losses and topographical changes to increase the knowledge about the ongoing activity in particular five tandem x bistatic acquisitions have been commanded between august 01 2014 and november 08 2014 two of them before the volcanic eruption and three of them during the event additionally to fully cover the volcanic activity the lava field 48 km north east of the caldera has also been monitored in the first part of the paper the expected elevation accuracy is studied on two levels absolute and relative height accuracies are analyzed by inspecting the x band signal propagation into snow and by investigating the impact of the main geometrical system parameters and the local geomorphology in the second part of the paper the analysis is applied to the bar arbunga volcanic system including a validation performed using complementary altimeter data the main geophysical outcome is the accurate temporal height tracking of the entire caldera and the glacial volcanic system the measured volume loss at the caldera location is about 1 billion cubic meters in two months with an average rate of subsidence of nearly 50 cm day these numbers confirm other independent sources and can be compared to lava volume measurements finally the last segment of the dyke that propagated from the bar arbunga caldera to the holuhraun lava field is mapped and a graben structure with a width of up to 1 km and a sinking of a few meters is reported

effect of different land use land cover on karst hydrogeochemistry a paired catchment study of chenqi and dengzhanhe puding guizhou sw china summary rainfall spring stage water temperature ph and conductivity in the paired karst spring catchments of chenqi and dengzhanhe which shared the same climatic condition but different land use land cover lulc at puding guizhou province sw china were monitored by two high resolution multi parameter auto recordable instrument of ctdp300 during the hydrological year of september 2007 september 2008 other monthly hydrogeochemical and carbon isotopic 13c variations in the paired karst catchments during the same hydrological year were also investigated a thermodynamic model was used to link the continuous data to monthly hydrogeochemical data allowing the calculation of co2 partial pressure pco2 and calcite saturation index sic on a continuous basis the primary study objective was to understand how the karst processes and karst hydrogeochemistry respond to different lulc which is essential to assessing the karst related carbon cycle marked seasonal and storm scale variations were found for ph conductivity pco2 sic and 13c of the two springs indicating that both springs were dynamic and variable systems however there were differences in the magnitude and direction of the variations of these features between the two springs the higher pco2 and hco 3 concentration and lower ph sic and 13c in chenqi spring than those in dengzhanhe spring tend to be related to the difference in lulc between chenqi and dengzhanhe spring catchments in the chenqi spring catchment there was larger soil cover and the paddy land was located in the discharge area both of which produced and kept more co2 a major driving agent for the karst processes and lower 13c in the soil aquifer system while in the dengzhanhe spring catchment area there was larger bare carbonate rock occurrence and the paddy land was located mainly in the recharge area moreover the ph increased and pco2 decreased generally in chenqi spring after rainfall possibly due to more carbonate dissolution in the larger soil cover rich in limestone fragments in the spring catchment while the ph decreased and pco2 increased generally in dengzhanhe spring after rainfall all these differences show that soil cover and land use pattern played important roles in the karst processes in other words the karst hydrogeochemistry and the karst related carbon cycle could be regulated effectively by different lulc in addition the higher concentrations of ca2 so 4 2 mg2 and conductivity of dengzhanhe spring were due to the dissolution of more gypsum and dolomite minerals in the strata of dengzhanhe spring catchment therefore the karst hydrogeochemical parameters including ph conductivity hco 3 ca2 mg2 so 4 2 pco2 sic and 13cdic could serve as good indicators of different lulc and the other environmental changes

characteristics of water stable isotopes and hydrograph separation in baishui catchment during the wet season in mt yulong region south western china glaciers are of crucial importance for the livelihood of the local populations which depend on their meltwater for water and energy supplies for this reason seasonal variations of oxygen 18 of glacial stream water and their sources within a small glacial catchment in south western china were investigated during the wet season the results showed significant difference of oxygen 18 existed among meltwater rainwater ground water and stream water and significantly seasonal variation of precipitation occurred during the observed period the streamflow of baishui catchment was separated into components of ice snowmelt and precipitation using oxygen 18 as shown by the result of the two component mixing model on average 53 4 of the runoff came from ice snowmelt during the wet season whereas the remaining 46 6 were contributed by precipitation in the catchment according to monthly hydrograph the contribution of snow and glacier meltwater varied from 40 7 to 62 2 and that of precipitation varied from 37 8 to 59 3 in wet season uncertainties for this separation were mainly caused by the variation of tracer concentrations the roles of glacier and snow meltwater should be noticed in water resource management in those glacial regions in south western china copyright c 2012 john wiley sons ltd

chemical weathering in glacial environments do glaciers enhance or inhibit chemical weathering rates relative to other environments the importance of glaciers in the global carbon cycle and climate change hinges on the answer we show that catchments occupied by active alpine glaciers yield cation denudation rates greater than the global mean rate but do not exceed rates in nonglacial catchments with similar water discharge silica denudation rates are distinctly lower in glacier covered catchments than in their nonglacial counterparts because sediment yields are high from glaciers this suggests that water flux rather than physical erosion exerts the primary control on chemical erosion by glaciers potassium and calcium concentrations are high relative to other cations in glacial water probably due to dissolution of soluble trace phases such as carbonates exposed by comminution and cation leaching from biotite preferential weathering of biotite may result in higher 87 sr 86 sr in glacial runoff than expected from whole rock compositions thus although glaciers do not influence total chemical denudation rates at a given runoff they may yield compositionally distinctive chemical fluxes to the oceans disruption of mineral lattices by grinding increases dissolution rates this and high surface area should make glacial sediments exceptionally weatherable weathering of glacial erosion products in environments beyond the glacier margin deserves attention because it may figure prominently in global chemical cycles

satellite derived digital elevation model dem selection preparation and correction for hydrodynamic modelling in large low gradient and data sparse catchments digital elevation models dems that accurately replicate both landscape form and processes are critical to support modelling of environmental processes topographic accuracy methods of preparation and grid size are all important for hydrodynamic models to efficiently replicate flow processes in remote and data scarce regions high resolution dems are often not available and therefore it is necessary to evaluate lower resolution data such as the shuttle radar topography mission srtm and advanced spaceborne thermal emission and reflection radiometer aster for use within hydrodynamic models this paper does this in three ways i assessing point accuracy and geometric co registration error of the original dems ii quantifying the effects of dem preparation methods vegetation smoothed and hydrologically corrected on hydrodynamic modelling relative accuracy and iii quantifying the effect of the hydrodynamic model grid size 30 2000 m and the associated relative computational costs run time on relative accuracy in model outputs we initially evaluated the accuracy of the original srtm 30 m seamless c band dem srtm dem and second generation products from the aster aster gdem against registered survey marks and altimetry data points from the ice cloud and land elevation satellite icesat srtm dem rmse 3 25 m had higher accuracy than aster gdem rmse 7 43 m based on these results the original version of srtm dem the aster gdem along with vegetation smoothed and hydrologically corrected versions were prepared and used to simulate three flood events along a 200 km stretch of the low gradient thompson river in arid australia using five metrics peak discharge peak height travel time terminal water storage and flood extent the hydrologically corrected dems performed best across these metrics in simulating floods compared with vegetation smoothed dems and original dems the response of model performance to grid size was non linear and while the smaller grid sizes 120 m improved the hydrodynamic model results these offered only slight improvements at very significant computational costs compared to grid size of 120 m with grid sizes 250 m and greater decreasing in model accuracy this study highlights the important impact that the quality of the underlying dem has and in particular how sensitive hydrodynamic models are to preparation methods and how important vegetation smoothing and hydrological correction of the base topographic data for modelling floods in low gradient and multi channel environments

eruption of the nevado del ruiz volcano colombia on 13 november 1985 tephra fall and lahars a small plinian eruption of the nevado del ruiz volcano in colombia ejected 3 5 x 1010 kilograms of mixed dacite and andesite tephra on 13 november 1985 with a maximum column height of 31 kilometers above sea level small pyroclastic flows and surges generated during the initial stage of the eruption caused surface melting of approximately 10 of the volcano9s ice cap leading to meltwater floods the erosive floods incorporated soils and loose sediments from the volcano9s flanks and developed into lahars which claimed at least 25 000 lives

straightforward reconstruction of 3d surfaces and topography with a camera accuracy and geoscience application topographic measurements for detailed studies of processes such as erosion or mass movement are usually acquired by expensive laser scanners or rigorous photogrammetry here we test and use an alternative technique based on freely available computer vision software which allows general geoscientists to easily create accurate 3d models from field photographs taken with a consumer grade camera the approach integrates structure from motion sfm and multi view stereo mvs algorithms and in contrast to traditional photogrammetry techniques it requires little expertise and few control measurements and processing is automated to assess the precision of the results we compare sfm mvs models spanning spatial scales of centimeters a hand sample to kilometers the summit craters of piton de la fournaise volcano with data acquired from laser scanning and formal close range photogrammetry the relative precision ratio achieved by sfm mvs measurement precision observation distance is limited by the straightforward camera calibration model used in the software but generally exceeds 1 1000 i e centimeter level precision over measurement distances of 10s of meters we apply sfm mvs at an intermediate scale to determine erosion rates along a 50 m long coastal cliff seven surveys carried out over a year indicate an average retreat rate of 0 70 0 05 m a 1 sequential erosion maps at 0 05 m grid resolution highlight the spatio temporal variability in the retreat with semivariogram analysis indicating a correlation between volume loss and length scale compared with a laser scanner survey of the same site sfm mvs produced comparable data and reduced data collection time by 80

late twentieth century changes in glacier extent in the ak shirak range central asia determined from historical data and aster imagery 1 global analysis of glacier regimes reveals widespread wastage since the late 1970s with a marked acceleration in the late 1980s we investigate changes in the heavily glacierized ak shirak range central tien shan plateau 43 n 75 e using air photo mapping surveys 1943 and 1977 an aster imagery 2001 and long term glaciological and meteorological observations the wasting of the ak shirak glacier system features a decrease in average glacier size and an increase in the area of outcrops a small shrinkage during 1943 1977 was followed by a greater than 20 reduction during 1977 2001 in response to increases in summer and annual air temperature and decreases in annual precipitation

rapid updating and improvement of airborne lidar dems through ground based sfm 3 d modeling of volcanic features we present a workflow to create scale georeference and integrate digital elevation models dems created using open source structure from motion sfm multiview stereo mvs software into existing dems as derived from the light detection and ranging data in the presented cases the workflow also maps the root mean square error between the base dem and the sfm surface model this allows dem creation from field based surveys using consumer grade digital cameras with open source and custom built software we employ this workflow on three examples of different scales and morphology 1 a scoria cone on mt etna 2 a lava channel on mauna ulu k lauea and 3 a flank collapse scar on mt etna this represents a new approach for rapid low cost construction and updating of existing dems at high temporal and spatial resolutions and for areas of up to several thousand square meters we assess the self consistency of the method by comparison of dems of the same features created from independent data sets acquired on the same day and from the same vantage points we further evaluate the effect of grid cell size on the reconstruction error this method uses existing dems as a georeferencing tool and can therefore be used in limited access and potentially hazardous areas as it no longer relies exclusively on control targets on the ground

dip slip rate determined by cosmogenic surface dating on a holocene scarp of the daju fault yunnan china abstract the daju and lijiang daju fault zones which bound the yulong mountains on its northern and eastern perimeters respectively are segments of a continuous fault system that bends at daju uplift of the yulong mountains the southernmost glacierized mountain range in eurasia resulted from the normal faulting characteristics of the fault system using cosmogenic surface exposure dating with 10 be and 26 al we have measured bedrock exposure ages as a function of elevation along an exposed bedrock scarp of the daju fault 10 be and 26 al exposure ages increase monotonically with elevation ranging from 2 6 to 9 6 ka over the 51 m scarp length giving an average dip slip rate of 7 5 m ka during the holocene period and a vertical uplift rate of 5 7 m ka the 5 7 m ka holocene uplift rate and supporting geomorphic features suggest that the uplift of the yulong mountains mainly occurred in the quaternary the fast slip rate and seismic quiescence for the recent 2 8 ka call attention to the possible recurrence of large magnitude earthquake events along the fault zone

nevado del ruiz volcano colombia pre eruption observations and the november 13 1985 catastrophic event abstract an italian volcanological mission visited the nevado del ruiz volcano a few weeks before the catastrophic eruption of november 13 1985 fumarolic gases of arenas crater were sampled and analysed and proved to be basically a mixture of co2 and so2 indicative of a direct magmatic input to the surface environment the existence of high lahar risk was stressed in the mission s report delivered on october 22 1985 and some simple preparedness measures were recommended to local authorities some observations of the november 13 pyroclastic sequence on the summit glacier suggest that the climax of the ice melting occurred before the beginning of the sustained column plinian phase and was related to the early emplacement of pyroclastic flows

rates of chemical denudation and co2 drawdown in a glacier covered alpine catchment solute fluxes from a glacier covered alpine catchment are partitioned into components derived from sea salt acid aerosol dissolution of atmospheric co2 and crustal weathering the bulk of solute is crustally derived coupled sulfide oxidation and carbonate dissolution so cd and carbonation of carbonate minerals generate approximately equal amounts of solute chemical denudation constitutes 1 5 of solid denudation but is significantly higher than the continental average co2 drawdown by weathering reactions varies directly with discharge and suspended sediment load and inversely with meltwater p co2 if it is generally true that flushing rates control co2 drawdown in glacier covered catchments then glacially driven chemical weathering could be a significant factor in carbon cycling and climate change on glacial interglacial time scales