intraplate extension prior to continental extrusion along the ailao shan red river shear zone left lateral movement of the ailao shan red river shear zone lends support to the hypothesis of continental extrusion resulting from the collision of india with asia our new observations from northwestern yunnan china and northwestern vietnam on different sides of the shear zone demonstrate that the sinistral offset was 600 km according to correlations of permian triassic flood basalt successions and late paleogene highly potassic mafic magmas we conclude that the shear was propagating on the south china continental margin and does not correspond to a suture between south china and indochina furthermore the highly potassic magmas were emplaced from ca 40 to 30 ma before the shear movement which was caused by the late oligocene to early miocene ca 27 22 ma extrusion activity this suggests that a late eocene to early oligocene intraplate extension possibly induced by delamination of thickened continental lithosphere took place in northwestern yunnan or eastern tibet as a response to the india asia collision this extension and sea floor spreading of the south china sea that began ca 30 ma could have accounted for the initiation of the ailao shan red river shear zone

contemporary changes of the channel pattern and braided gravel bed floodplain under rapid small valley glacier recession scott river catchment spitsbergen abstract after the little ice age high latitude proglacial river catchments have been observed to transition to paraglacial conditions through the activation of fluvial processes and changes in the river valley and channel forms this project provides an analysis of contemporary changes in the morphology of the valley bottom and channel development of the proglacial scott river catchment nw part of the wedel jarlsberg land sw spitsbergen based on observations conducted during the 2009 2013 melt seasons almost half of the catchment area of 10 km2 is occupied by a valley glacier currently in the stage of rapid recession the processes driving the development of the glacier free valley floor are determined by 1 long term factors such as geological structure glaciotectonics or the morphogenesis of the terminoglacial zone 2 medium term factors including climatic changes and changes in the extent of the glacial terminus and hydrological regime and 3 short term factors such as weather driven flooding events geological factors determined the development of two valley narrowings and a clear division of the valley floor into three morphological zones the upper gorge in the terminal moraine rampart distinguishes the wide up to 700 m upper section of the valley bottom dominated by an outwash plain where the river system is fed by small tributaries the lower valley gorge dissecting the elevated marine terrace separates the middle section of the braided river floodplain from the mouth section alluvial fan the geomorphological field mapping of the valley floor and riverbed was conducted using geodesic and hydrometric measurements with high resolution survey techniques based on the global positioning system gps the detail measurements of the scott river valley and channel were carried out at representative cross sections and longitudinal profiles in various parts of the catchment because of the dominance of the glacial alimentation regime changes in the discharge rate and bedload transport regime are influenced by the glacial ablation rate which determines the variability of channel morphology and the contemporary development of the valley bottom the upper section of the valley is dominated by a multiple channel braided system fed by sub and supraglacial waters while in the middle section the development pattern changes from a meandering single thread channel to a multiple channel wandering system to a multiple channel braided system the current valley bottom is almost entirely occupied by a braided river floodplain and multiple channel river bed changes in the channel system are related to periods of snowmelt and the related flooding after the retreat of the snow cover the channels are highly stable as their spatial pattern is usually transformed during several days of ablation or ablation precipitation flood flows in the river s mouth section the channel returns to a single thread meandering pattern before transitioning to a multiple channel distribution system and finally to a single thread straight channel the river below the ebb in the storm bank develops a subaqual prodelta

disturbances in coarse bedload transport in a high mountain stream channel system western tatras poland abstract bedload transport measurements in the formerly glaciated chocholowski catchment located in the western tatras in poland were performed in the period 1975 to 2018 measurement of bedload displacement allowed to determine the role of bedload transport disturbances in both system connectivity and sediment transfer bedload transport occurred as many as triggered up to several times a year the longest distances were observed during rain on snow events between 12 m in headwaters and over 100 m in the fluvial valley bedload became activated along the entire length of the channel system 10 5 km every 2 to 5 years when the stream discharge exceeded 10 m3 s 1 with an average of 1 25 m3 s 1 in such situations bedload dynamics increased downstream and stream power was sufficient to overcome local barriers i e boulder and log steps downstream increases in bedload dynamics may become disturbed and inverted by sudden snowmelt and locally heavy rainfall these types of events caused the dynamics of bedload transport to be 190 to 320 greater in the upper part of the studied catchment and to decline in the downstream direction over a distance of 7 km to yield an attenuation effect the same pattern was observed in local tributaries where the dynamics of bedload transport were 200 higher in the upper part and attenuation was observed along a distance of 1 5 km in the downstream direction all events of this type cause seasonal disturbances in bedload transport however the greatest effect on bedload dynamics was produced by natural deforestation a 16 decrease in forest cover causes a fluvial system disequilibrium manifested in an intensification of hydro geomorphologic processes and formation of new landforms

fracture patterns at lava ice contacts on kokostick butte or and mazama ridge mount rainier wa implications for flow emplacement and cooling histories abstract cooling lava commonly develop polygonal joints that form equant hexagonal columns such fractures are formed by thermal contraction resulting in an isotropic tensional stress regime however certain linear cooling fracture patterns observed at some lava ice contacts do not appear to fit the model for formation of cooling fractures and columns because of their preferred orientations these fracture types include sheet like ladder like rectangular fracture pattern intermediate pseudo aligned individual column bounding fractures and pseudopillow straight to arcuate fractures with perpendicular secondary fractures caused by water infiltration fractures that form the edges of multiple columns along a single linear fracture despite the relatively common occurrence of these types of fractures at lava ice contacts their significance and mode of formation have not been fully explored this study investigates the stress regimes responsible for producing these unique fractures and their significance for interpreting cooling histories at lava ice contacts data was collected at kokostick butte dacite flow at south sister or and mazama ridge andesite flow at mount rainier wa both of these lava flows have been interpreted as being emplaced into contact with ice and linear fracture types have been observed on their ice contacted margins two different mechanisms are proposed for the formation of linear fracture networks one possible mechanism for the formation of linear fracture patterns is marginal bulging melting of confining ice walls will create voids into which flowing lava can deform resulting in margin parallel tension causing margin perpendicular fractures if viewed from the ice wall these fractures would be steeply dipping linear fractures another possible mechanism for the formation of linear fracture types is gravitational settling pure shear during compression and settling can result in a tensional environment with similar consequences as marginal inflation in addition to this horizontally propagating cooling fractures will be directly influenced by viscous strain caused by the settling of the flow this would cause preferential opening of fractures horizontally resulting in vertically oriented fractures it is important to note that the proposed model for the formation of linear fractures is dependent on contact with and confinement by glacial ice the influence of flow or movement on cooling fracture patterns has not been extensively discussed in previous modeling of cooling fractures rapid cooling of lava by the interaction with water and ice will increase the ability to the capture and preserve perturbations in the stress regime

determination of the bedload transport rate in a small proglacial high arctic stream using direct semi continuous measurement abstract the article presents the results of a 34 day series of direct semi continuous measurements of the bedload transport performed during the melt season 2013 in the scott river catchment nw part of the wedel jarlsberg land spitsbergen the daily variability of the bedload transport rates and its relation to the dissolved and suspended load were analysed in two cross sections located in the lower course of a proglacial gravel bed river the bedload flux was measured by means of two 4 module sets of river bedload traps rbt in the research period a total of 34 day long samples of bedload and 34 water samples for the determination of the dissolved and suspended load were collected in each of the two cross sections 200 m apart the measurements showed longitudinal and temporal variability of bedload flux and the remaining components solutions suspensions corresponding with changes in water discharge the mean daily bedload flux qb in consecutive measurement cross sections xs amounted to 124 kg d 1 xs i and 59 kg d 1 xs ii respectively and showed high variability and an evident relationship with temperature the unequal bedload flux of the two measuring stations xs i and xs ii suggests aggradation within the alluvial fan that separates the two reaches the volume and rate of bedload flux were determined by the frequency of the occurrence of flood flows during which approximately from 59 xs i to 77 xs ii of total bedload was discharged the highest recorded daily values constituted 12 of total bedload flux through the cross section below the alluvial fan the river discharged approximately 6 million cubic meters m m3 of water 3 t of bedload lb 2238 t of suspended load ls and 613 t of dissolved load ld the relationships between the three components of the load suggest a 500 fold excess of suspended load and a 100 fold excess of dissolved load in relation to bedload flux high temporal and latitudinal variability of the bedload transport rate resulted in changes in the channel morphology and during floods also the floodplain

understanding sedimentation in the song hong yinggehai basin south china sea the cenozoic song hong yinggehai basin in the south china sea contains a large volume of sediment that has been used in previous studies together with regional geomorphology to argue for the existence of a large palaeodrainage system that connected eastern tibet with the south china sea to test this and to understand the significance of sediment volumes deposited in the song hong yinggehai basin this study compared erosion histories of source regions with sediment volumes deposited during the two main stages in basin evolution spanning active rifting and subsidence 30 15 5 ma and postrift sedimentation 15 5 ma to present the study of basin provenance by detrital zircon u pb dating revealed hainan was an important and continuous source of sediment and a bedrock thermochronological study quantified its overall contribution to basin sedimentation comparison between the accumulated mass of basin sediment and volumes of eroded bedrock calculated from apatite thermochronometry across the modern red river drainage in northern vietnam as well as hainan island accounted for the bulk of sediment deposited since 30 ma consequently if an expanded paleodrainage ever existed it must have predated the oligocene

insight into the origin of the tengchong intraplate volcano and seismotectonics in southwest china from local and teleseismic data received 18 june 2008 revised 22 february 2009 accepted 10 march 2009 published 13 may 2009 1 a high resolution tomographic image of the crust and upper mantle under yunnan province in southwest china was determined by using a large number of teleseismic data measured precisely from digital seismograms as well as local earthquake arrival times recorded by the dense yunnan seismic network the grid spacing of the tomographic model is 70 km 78 km in the horizontal directions and 4 70 km in depth our resulting model shows a clear low velocity low v 0 3 with respect to the average one dimensional velocity model column extending from the surface down to about 400 km depth under the active tengchong volcano and some high velocity high v anomalies existing in the mantle transition zone furthermore the low vanomaly extends horizontally toward the northeast at 250 to 400 km depth combining our tomographic results with geochemical and geological investigations we infer that the tengchong volcano is a rift related volcano caused by the subduction and dehydration of the indian plate as well as corner flow in the mantle wedge though the subducted slab is a continental plate our results show that the upwelling flow under tengchong originates at 400 km depth a prominent low v anomaly along the red river fault zone extends down to the upper mantle 100 km depth reflecting that the red river fault zone may have cut through the crust to the upper mantle the two dayao earthquakes m 6 1 and m 6 2 in 2003 occurred on the margin of high v anomalies and are underlain by a prominent low v anomaly in the lower crust and upper mantle suggesting that the dayao earthquakes may be associated with fluids released from the dehydration of the subducted indian slab these results are significantly improved compared with previous studies and provide new seismic constraints on the dynamic processes of the india asia collision

spatial distribution of sediment storage types and quantification of valley fill deposits in an alpine basin reintal bavarian alps germany spatial patterns of sediment storage types and associated volumes using a novel approach for quantifying valley fill deposits are presented for a small alpine catchment 17 km 2 in the bavarian alps the different sediment storage types were analysed with respect to geomorphic coupling and sediment flux activity the dominant landforms in the valley in terms of surface area were found to be talus slopes sheets and cones followed by rockfall deposits and alluvial fans and plains more than two thirds of the talus slopes are relict landforms completely decoupled from the geomorphic system notable sediment transport is limited to avalanche tracks debris flows and along floodplains sediment volumes were calculated using a combination of polynomial functions of cross sections seismic refraction and gis modelling a total of 66 seismic refraction profiles were carried out throughout the valley for a more precise determination of sediment thicknesses and to check the bedrock data generated from geomorphometric analysis we calculated the overall sediment volume of the valley fill deposits to be 0 07 km 3 this corresponds to a mean sediment thickness of 23 3 m the seismic refraction data showed that large floodplains and sedimentation areas which have been developed through damming effects from large rockfalls are in general characterised by shallow sediment thicknesses 20 m by contrast the thickness of several talus slopes is more than twice as much for some locations e g narrow sections of valley the polynomial generated cross sections resulted in overestimations of up to one order of magnitude whereas in sections with a moderate valley shape the modelled cross sections are in good accordance with the obtained seismic data for the quantification of valley fill deposits a combined application of bedrock data derived from polynomials and geophysical prospecting is highly recommended d 2003 elsevier b v all rights reserved

surface cooling advection and the development of different surface textures on active lavas on kilauea hawai i the validity of lava flow cooling models were investigated using data from a high resolution high frame rate thermal imaging camera on kilauea hawai i during august 2004 once the surface temperature data for small lava flow and lobes were corrected for emissivity viewing distance humidity and viewing angle it was clear that their upper surfaces were thermally stratified on eruption the interior of a stationary lava lobe was exposed by removing the crust and its cooling rate was measured at 30 hz for this flow the measured cooling trend was successfully modelled using a finite difference cooling model however modelled and measured cooling rates of a pahoehoe lobe and a small channelised lava flow were only in agreement until the crust began to deform the departure from the modelled trend at this point is attributed to two factors one is the complex cooling regime of a highly deformed ropy crust in which exposed lava at the crests of the ropes radiates in all directions compared with lava in the troughs where radiative cooling is less effective the second and more important reason for the difference is the reduced flow rate of the crust once it begins to be compressed the underlying visco elastic zone beneath the crust flows more rapidly than the crust and consequently advective heat flow significantly reduces cooling rates variations in heat loss from different flow textures and the incorporation of different advective heat components is clearly important in future flow models one of the critical parameters in such models is the temperature at which different surface textures develop temperature profiles along lobes and flows also revealed that rope textures developed on pahoehoe lavas when temperatures were in the range of 700 800 c brittle deformation of pahoehoe crust occurred when temperature dropped below 700 c and small pahoehoe lobes stopped advancing at temperatures of 600 650 c it is important to recognise that the flow front temperatures at which these flows stop advancing will be significantly greater than for larger flows on similar gradients the higher internal and basal shear stresses of large lava flows will allow the flow to advance until the visco elastic layer at the front of a front is significantly cooler than the temperatures recorded on these small flows on kilauea

the evidence for paraglacial sedimentation and its temporal scale in the deglacierizing basin of small river glacier canada abstract spatially sampled suspended sediment data from extra channel surfaces of different ages during rainfall events were used to infer the timescale of landscape adjustment to little ice age lia deglacierization at small river glacier canada surface ages were determined by aerial photograph interpretation turbidimeters were installed in three ephemeral channels on young mature and old surfaces and their response to rainfall events of different magnitudes recorded results showed young ice proximal surfaces exposed since 1977 were increasingly vulnerable to mobilization during rainfall events a suspended sediment response from old surfaces exposed since 1910 was recorded for only three events with 5 and 30 year return periods the intensity and duration of rainfall events therefore had to increase in magnitude to mobilize sediment on surfaces of increasing maturity hysteresis in the channel suspended sediment response further confirmed the dependence of surface response on rainfall event magnitude the rapid temporal decline in surface response indicated that surface armoring or sediment exhaustion is stabilizing surfaces within decades of exposure from the lia maximum ca 1910 at small river glacier however further perturbation for example by glacial advance or extreme climatic events would likely modify the pattern of suspended sediment yields by changing terrain surface mobilization thresholds and reconfiguring channel sediment stores we therefore suggest that it is difficult to determine when paraglacial sedimentation ceases to influence suspended sediment yields and therefore significantly limiting the usefulness of the term to describe the period of suspended sediment yield adjustment following deglacierization

petrogenesis of late eocene high ba sr potassic rocks from western yangtze block se tibet a magmatic response to the indo asian collision abstract the indo asian collision resulted in extrusion of the indochina block along the ailao shan red river asrr shear zone in the cenozoic with the emplacement of widespread potassic magmatic rocks in this contribution we investigated five potassic felsic intrusions exposed in the western yangtze block adjacent to the asrr shear zone including the xiaoqiaotou jianchuan yuzhaokuai laojunshan and south taohuacun intrusions new la icp ms zircon u pb results in combination with previous data indicate that these felsic rocks have identical crystallization ages of 36 35 ma they are characterized by high ba mostly 1500 ppm and sr mostly 1000 ppm abundances with high k 2 o contents and k 2 o na 2 o ratios they exhibit similar sr nd isotopic components as the coeval shoshonitic mafic rocks exposed in the studied area elemental and isotopic data suggest that the five intrusions were likely derived from fractional crystallization of shoshonitic mafic magmas originating from an enriched lithospheric mantle on the basis of previously published data and results in this paper we considered that the lithospheric mantle underneath the western yangtze might have undergone enrichment events twice at least including the neoproterozoic oceanic subduction and the neo tethyan oceanic subduction

a m gurnell and m j clark eds 1987 glacio fluvial sediment transfer an alpine perspective chichester etc john wiley and sons ltd

volcanic plume and bomb field masses from thermal infrared camera imagery masses erupted during normal explosions at stromboli volcano italy are notoriously difficult to measure we present a method that uses thermal infrared video for cooling bomb fields to obtain the total power emitted by all hot particles emitted during an explosion a given mass of magma m will emit a finite amount of thermal power defined by m cp te t0 cp and te being magma specific heat capacity and temperature and t0 being ambient temperature we use this relation to convert the total power emitted by the bomb field to the mass required to generate that power to do this we extract power flux curves for the field and integrate this through time to obtain total power e this is used to estimate mass q in q e cp te t0 when applied to individual bombs we obtain masses of between 1 and 9 kg per bomb or a volume of 970 and 6500 cm3 these volumes equate to spheres with diameters 12 and 27 cm for the entire bomb field we obtain volumes of 7 28 m3 we calculate masses for 32 eruptions and obtain typical bomb masses of between 103 and 104 kg per eruption in addition we estimate that between 102 and 103 kg of gas and ash are emitted as part of a mixed plume of bombs gas and ash we identify two types of eruption on the basis of the erupted bomb masses and the ratio of the plume s gas and ash component to the bomb component the first type is bomb dominated is characterized by bomb masses of 104 kg and has ash gas bomb ratios of 0 02 the second type is ash and gas dominated is characterized by erupted bomb masses of 103 kg and has ash gas bomb ratios of around one and as high as two there is no correlation between the quantity of bombs and quantity of gas ash erupted in addition while source pressure for each explosion correlates with the quantity of gas and ash erupted the mass of bombs emitted varies independently of pressure

search for active lava flows with virtis on venus express there are several lines of evidence suggesting that effusive volcanism still shapes the surface of venus but the rate is not well constrained the preservation of impact craters is consistent with a rate of 1 km year comparable to earth intraplate volcanism as well as a rate several orders of magnitude less it has been proposed to search images of the venus nightside near 1 m for the excess thermal emission of active lava flows the scattering of photons in the optically thick cloud cover is similar in effect to a gaussian blur with a full width half maximum fwhm of 90 km this reduces the maximum intensity of the anomalies introduced by eruptions making detection more difficult than in a clear atmosphere but also provides larger targets for imaging the virtis instrument on venus express observed surface thermal emission at 1 02 m wavelength between april 2006 and october 2008 at a spatial resolution of typically a few tens of km we have searched the 1000 images for the signatures of active lava flows in form of transient excess emission measured in several adjacent pixels we estimate that eruptions with 1gw m sr total excess specific thermal emission would be clearly visible compared to the instrumental and atmospheric noise but no such anomalies were detected it has been shown that the total thermal emission of eruptions on earth can be related to the lava discharge rate we adjust this model to the venus surface environment by adjusting observed lava surface temperature distributions and estimate that a discharge rate on the order of 1000 m s is required to produce an anomaly clearly identifiable in virtis data this is a relatively high value for effusive volcanism but a few historical eruptions on earth surpassed it adopting a fit to the discharge rates of historical eruptions on hawaii as a model 4 to 10 of the eruptions in the field of view of virtis images would have been detectable in addition to the low detection probability the low surface coverage of on average 1 of the surface per day over a period of 800 days indicates that the probability of an eruption imaged by virtis was low to begin with therefore the virtis data set fails to provide a useful constraint on the rate of volcanism on venus venus express continues to observe surface thermal emission with the venus monitoring camera for future missions near infrared imaging would profit from more frequent images of the same area than is possible from the excentric 24h orbit of venus express the superrotation of the cloud cover allows to reduce atmospheric noise by averaging of images taken hours apart and the detection of eruptions with 100 m s lava or less might then be possible nevertheless searching for lava flows emplaced between two observations of the same surface by high resolution radar imaging altimetry or interferometry generally provides a better constraints than infrared imaging for the same observation duration and surface coverage however high resolution radar and low resolution infrared observations are highly complementary and could be accommodated on the same mission preferably with a low circular polar orbit

best fit results from application of a thermo rheological model for channelized lava flow to high spatial resolution morphological data 1 the flowgo thermo rheological model links heat loss core cooling crystallization rheology and flow dynamics for lava flowing in a channel we fit this model to laser altimeter lidar derived channel width data as well as effusion rate and flow velocity measurements to produce a best fit prediction of thermal and rheological conditions for lava flowing in a 1 6 km long channel active on mt etna italy on 16th september 2004 using as a starting condition for the model the mean channel width over the first 100 m 6 m and a depth of 1 m we obtain an initial velocity and instantaneous effusion rate of 0 3 0 6 m s and 3 m3 s respectively this compares with field and lidar derived values of 0 4 m s and 1 4 m3 s the best fit between model output and lidar measured channel widths comes from a hybrid run in which the proximal section of the channel is characterised by poorly insulated flow and the medial distal section by well insulated flow this best fit model implies that flow conditions evolve down channel where hot crusts on a free flowing channel maximise heat losses across the proximal section whereas thick stable mature crusts of a a clinker reduce heat losses across the medial distal section this results in core cooling per unit distance that decreases from 0 02 0 015 c m 1 across the proximal section to 0 005 c m 1 across the medial distal section this produces an increase in core viscosity from 3800 pa s at the vent to 8000 pa s across the distal section

geomorphic effectiveness sandur development and the pattern of landscape response during jokulhlaups skeiðararsandur southeastern iceland by contrast with other historical outburst floods on skeitararsandur the 1996 jokulhlaup was unprecedented in its magnitude and duration attaining a peak discharge of f53 000 m 3 s in 17 h using a combination of field sampling and remote sensing techniques landsat tm sar interferometry airphotos and laser altimetry we document the sandur wide geomorphic impacts of this event these impacts varied widely across the skeitararsandur and cannot be singularly attributed to jokulhlaup magnitude because pre jokulhlaup glacial dynamics and the extant setting largely conditioned the spatial pattern type and magnitude of these impacts topographic lowering and asymmetric retreat of the ice front during the late twentieth century has decoupled the ice sheet from the moraine sandur complex along the central and western sandur this glacial control in combination with the convex topography of the proximal sandur promoted a shift from a primarily diffuse source braided outwash system to a more point sourced channelized discharge of water and sediment deposition dominated within the proglacial depression with approximately 3 8 10 7 m 3 of sediment and along channel systems that remained connected to subglacial sediment supplies this shift to a laterally dissimilar channelized routing system creates a more varied depositional pattern that is not explicitly controlled by the concave longitudinal profile down sandur laterally contiguous units therefore may vary greatly in age and sediment character suggesting that current facies models inadequately characterize sediment transfers when the ice front is decoupled from its sandur water was routed onto the sandur in a highly organized fashion and this jokulhlaup generated major geomorphic changes including sandur incision in normally aggradational distal settings and eradication of proximal glacial landforms dating to fa d 1892 d 2002 elsevier science b v all rights reserved

generation of fine hydromagmatic ash by growth and disintegration of glassy rinds 1 the deposits of mafic hydromagmatic eruptions are more fine grained and variable in vesicularity than dry magmatic deposits blocky equant shapes of many hydromagmatic clasts also contrast with droplet thread and bubble wall morphology of dry magmatic fragments small 180 m blocky hydromagmatic pyroclasts have traditionally been interpreted to result from discrete vapor explosions although such explosions tend to occur only under certain conditions this paper considers a process of hydromagmatic ash formation that involves repeated growth and disintegration of glassy rinds on pyroclast surfaces as they deform within turbulent flows this process termed turbulent shedding may occur during the expansion phase of vapor explosions or during turbulent but nonexplosive mixing of magma with water steam or water sprays the occurrence of turbulent shedding and the resulting fragment sizes depend on the timescale for rind growth and the timescale between disturbances that remove or disintegrate glassy rinds turbulent shedding is directly observable in some small littoral jets at kilauea calculations suggest that in the presence of liquid water or water sprays glassy rinds having a thickness of microns to millimeters should form in milliseconds to seconds this is similar to the timescale between turbulent velocity fluctuations that can shred lava globules and remove such rinds the fraction of a deposit consisting of fine ash should increase with the duration of this process large scale surtseyan jets generate hundreds or thousands of shedding events bubble bursts or tephra jets at kilauea s coast may produce only a few

constraints on cenozoic regional drainage evolution of sw china from the provenance of the jianchuan basin 1 detrital zircon u pb geochronology was applied to cenozoic fluvial sedimentary rocks from the jianchuan basin yunnan province china to constrain the provenance and the nature of paleo drainage local geology testifies to a large river flowing through the jianchuan basin during the paleogene and this previously has been linked to a paleo drainage system that connected the qiangtang and lhasa blocks to the south china sea the detrital zircon results from this study do not fit with this model and instead show provenance consistent with a river draining a watershed within the songpan garze complex most likely from the northeast from the late oligocene and thereafter zircon provenance records greater contributions from erosion of local sources that surround the basin including the south china block and yidun arc rocks that suggest loss of the northern sources the timing for these changes overlap with regional deformation related to strike slip faulting or displacement by shear strain rather than the later uplift associated with an expanding margin of the tibetan plateau

controls on downstream variation in surficial sediment size of an outwash braidplain developed under high arctic conditions kaffioyra svalbard abstract the changes in morphology and surficial sediments of an outwash braidplain developed under high arctic conditions are closely related to geomorphic processes tectonic conditions and climate variations and are affected by the existence of permafrost these factors control the changes in river channel slope their morphology and active braidplain width which influence the downstream variation in grain size of outwash surficial sediments interdependence between these parameters has not previously been considered in relation to the spatial distribution of surficial sediments of outwash braidplain developed in the forefield of a retreating subpolar glacier in this study controls affecting the surficial lithology of the waldemar river outwash nw spitsbergen svalbard were recognised and indicated multiple correlations between the downstream changes in sediment texture the geomorphometry of distributary channels and outwash surface slope due to this the techniques of multivariate regression modelling artificial neural network and multivariate adaptive regression splines were used results show that observed relations between the sedimentary and morphological features indicate the existence of thresholds for downstream variation in bed material size which are not constant moreover the processes of sediment transport in an outwash braidplain are strictly related to shields stress which is proportional to changes in braidplain slope median grain diameter and sediment sorting in the proximal and middle zones of the outwash but is inversely proportional to median grain diameter in the distal zone contrary to shields bed material threshold entrainment model the results of this study will help understand outwash fan and plain evolution in paraglacial landscapes under conditions of changeable rate and source of sediment supply and transport capacity

contemporary geomorphological activity throughout the proglacial area of an alpine catchment abstract quantification of contemporary geomorphological activity is a fundamental prerequisite for predicting the effects of future earth surface process and landscape development changes however there is a lack of high resolution spatial and temporal data on geomorphological activity within alpine catchments which are especially sensitive to climate change human impacts and which are amongst the most dynamic landscapes on earth this study used data from repeated laser scanning to identify and quantify the distribution of contemporary sediment sources and the intensity of geomorphological activity within the lower part of a glaciated alpine catchment odenwinkelkees central austria spatially geomorphological activity was discriminated by substrate class activity decreased in both areal extent and intensity with distance from the glacier becoming progressively more restricted to the fluvially dominated valley floor temporally geomorphological activity was identified on annual seasonal weekly and daily timescales activity became more extensive with increasing study duration but more intense over shorter timescales thereby demonstrating the importance of temporary storage of sediment within the catchment the mean volume of material moved within the proglacial zone was 4400 m 3 yr 1 which suggests a net surface lowering of 34 mm yr 1 in this part of the catchment we extrapolate a minimum of 4 8 mm yr 1 net surface lowering across the whole catchment these surface lowering values are approximately twice those calculated elsewhere from contemporary measurements of suspended sediment flux and of rates calculated from the geological record perhaps because we measure total geomorphological activity within the catchment rather than overall efflux of material repeated geomorphological surveying therefore appears to mitigate the problems of hydrological studies underestimating sediment fluxes on decadal annual time scales further development of the approach outlined in this study will enable the quantification of geomorphological activity alpine terrain stability and persistence of landforms

numerical modeling of lava flow cooling applied to the 1997 okmok eruption approach and analysis 1 throughout february and march of 1997 okmok volcano in the eastern aleutian islands of alaska erupted a 6 km long lava flow of basaltic a a within its caldera a numerical model for lava flow cooling was developed and applied to the flow to better understand the nature of its cooling radiation and convection from the surface as well as conduction to the ground were used to transport the flow s heat to its surroundings in the model internally a conduction only approach moved heat from the interior outward vesiculation latent heat generation and thermal conductivity changes with temperature are among the other factors that were dynamically accounted for results indicate that ambient temperature fluctuations on the scale of days to weeks must be taken into account to create an accurate short term prediction of lava surface temperature daily data of rainfall and ambient temperature as opposed to yearly averages greatly increased the accuracy of the model furthermore convective cooling of the lava surface was observed to be a dominant heat loss process during the first 200 days indicating the convective heat transfer coefficient is a prime determinant of the accuracy of the model for predicting surface temperatures over a longer cooling period 2 years thermal conductivity and porosity proved to be among the dominating factors for heat loss because of the limiting role of conductive heat flow in the interior the model s flexibility allows application to flows other than the 1997 okmok eruption

the influence of topographic roughness on lava flow emplacement a quantitative understanding of the factors controlling lava flow emplacement is critical for both hazard assessment and mitigation and for the interpretation of past flow emplacement conditions the influence of topography with a vertical amplitude smaller than flow thickness i e substrate roughness is currently not accounted for in most flow emplacement models and hazard estimates here we measure the effect of substrate roughness on flow emplacement through experiments using analog fluids and molten basalt complementing recent work on the interaction of lava flows with obstacles taller than flow thickness we present results from three sets of analog experiments in which corn syrup polyethylene glycol and molten basalt were each extruded onto a sloping plane covered with a series of beds of varying grain sizes we find that flow front advance rates are impacted by bed roughness for all materials with decreases in average velocities by up to 50 with increases of substrate grain sizes by 5 100 times ranges analogous with topographic variations found in nature these decreases in flow front advance velocities are equivalent to up to an order of magnitude increase in fluid viscosity we interpret this velocity decrease to be caused by the movement of material into void spaces between substrate grains and by enhanced cooling through heat conduction to the substrate due to increased surface contact area the difference in advance velocity with increasing grain size diminishes with time after initial emplacement as a basal boundary layer is established additionally the experimental flow geometry measured by the complexity of the flow external perimeter became increasingly complex with increasing substrate grain size this effect will act to both slow the forward advance of lava flows and to create irregular emplacement paths of flows moving over rough surfaces we propose that flow emplacement models should be modified possibly through a calibrated effective viscosity term to account for bed roughness to increase accuracy in flow prediction and hazard estimation models

calculation of lava effusion rates from landsat tm data we present a thermal model to calculate the total thermal flux for lava flowing in tubes on the surface or under shallow water once defined we use the total thermal flux to estimate effusion rates for active flows at kilauea hawaii on two dates input parameters were derived from landsat thematic mapper tm field and laboratory measurements using these parameters we obtain effusion rates of 1 76 0 57 and 0 78 0 27 m3 s 1 on 23 july and 11 october 1991 respectively these rates are corroborated by field measurements of 1 36 0 14 and 0 89 0 09 m3 s 1 for the same dates kauahikaua et al 1996 using weather satellite avhrr data of lower spatial resolution we obtain similar effusion rates for an additional 26 dates between the two tm derived measurements we assume that although total effusion rates at the source declined over the period the shut down of the ocean entry meant that effusion rates for the surface flows alone remained stable such synergetic use of remotely sensed data provides measurements that can a contribute to monitoring flow field evolution and b provide reliable numerical data for input into rheological and thermal models we look forward to being able to produce estimates for effusion rates using data from high spatial resolution sensors in the earth observing system eos era such as landsat 7 the hyperspectral imager the advanced spaceborne thermal emission spectrometer and the advanced land imager

simulating the thermorheological evolution of channel contained lava flowgo and its implementation in excel flowgo is a one dimensional model that tracks the thermorheological evolution of lava flowing down a channel the model does not spread the lava but instead follows a control volume as it descends a line of steepest descent centred on the channel axis the model basis is the jeffreys equation for newtonian flow modified for a bingham fluid and a series of heat loss equations adjustable relationships are used to calculate cooling crystallization and down channel increases in viscosity and yield strength as well as the resultant decrease in velocity here we provide a guide that allows flowgo to be set up in excel in doing so we show how the model can be executed using a slope profile derived from google tm earth model simplicity and ease of source term input from google tm earth means that this exercise allows i easy access to the model ii quick global application and iii use in a teaching role output is tested using measurements made for the 2010 eruption of piton de la fournaise la reunion island the model is also set up for rapid syneruptive hazard assessment at piton de la fournaise as we show using the example of the response to the june 2014 eruption

origins and implications of zigzag rift patterns on lava lakes abstract the distinctive rift patterns observed on newly formed lava lakes are very likely a product of interaction between heat transfer cooling of lava and deformation of the solid crust in response to applied stresses one common pattern consists of symmetric zigzag rifts separating spreading plates zigzags can be characterized by two measurable parameters an amplitude a and an angle between segments that make up the zigzags similar patterns are observed in analog wax experiments in which molten wax acts as cooling and solidifying lava we perform a series of these wax experiments to find the relationship between a and the cooling rate we develop a model to explain the observed relationships is determined by a balance of spreading and solidification speeds the amplitude a is limited by the thickness of the solid wax crust theoretical predictions agree well with experimental data this enables us to scale the model to basaltic lava lakes if zigzag rifts are observed on the surface of lava lakes and if physical properties of the lava crust can be measured or inferred by other means measurements of and a make it possible to calculate crust spreading velocity and crust thickness

a multi dimensional analysis of pro glacial landscape change at solheimajokull southern iceland proglacial landscapes are some of the most active on earth previous studies of proglacial landscape change have often been restricted to considering either sedimentological geomorphological or topographic parameters in isolation and are often mono dimensional this study utilised field surveys and digital elevation model analyses to quantify planform elevation and volumetric proglacial landscape change at solheimajokull in southern iceland for multiple time periods spanning from 1960 to 2010 as expected the most intense geomorphological changes persistently occurred in the ice proximal area during 1960 to 1996 the proglacial river was relatively stable however after 2001 braiding intensity was higher channel slope shallower and there was a shift from overall incision to aggradation attributing these proglacial river channel changes to the 1999 jokulhlaup is ambiguous because it coincided with a switch from a period of glacier advance to that of glacier retreat furthermore glacier retreat of 40 m yr 1 coincided with ice marginal lake development and these two factors have both altered the proglacial river channel head elevation from 2001 to 2010 progressive increase in channel braiding and progressive downstream incision occurred these together probably reflecting stream power due to increased glacier ablation and reduced sediment supply due to trapping of sediment by the developing ice marginal lake overall this study highlights rapid spatiotemporal proglacial landscape reactions to changes in glacial meltwater runoff regimes glacier terminus position sediment supply and episodic events such as jokuhlaups recognising the interplay of these controlling factors on proglacial landscapes will be important for understanding the geological record and for landscape stability assessments

the heating of substrates beneath basaltic lava flows as populations around volcanoes grow the potential for society to be impacted by lava flows is increasing while lava flows are known to ignite bulldoze and or bury structures little is known about potential impacts to buried infrastructure we measure temperature profiles below molten rock to constrain a heat transfer model thermomagnetic and palaeomagnetic measurements on soil samples from beneath a 2014 hawaiian lava flow are then used to verify the model finally we illustrate the model s utility in lava flow hazard assessments by modelling a hypothetical lava flow active for 4 weeks in auckland new zealand the modelling predicts the upper 1 7 m of dry soil would exceed 100 c after 1 week and the upper 3 8 m of soil would exceed 100 c after 4 weeks determining the depth profile of substrate heating has important implications for planning and preparedness e g siting buried infrastructure volcanic impact and risk assessments and decision making before and during lava flow crises e g mitigation measures to be employed

outburst flood evolution at russell glacier western greenland effects of a bedrock channel cascade with intermediary lakes abstract glacial lake outburst floods have produced a distinctive and widespread quaternary record both onshore and offshore via widespread and intense geomorphological impacts yet these impacts remain poorly understood due to a lack of modern analogues this study therefore makes a systematic quantification of the evolution of a bedrock channelled outburst flood channel topography was obtained from digitised aerial photographs a 5 m grid resolution dem and bathymetric surveys flood inundation was measured in the field from dgps measurements flood evolution was analysed with application of a numerical model novel flood metrics including rate of rise to peak and persistence above a value of hydraulics were calculated the key findings were that outburst floods i that enter intermediary lakes are dramatically attenuated in terms of propagation whilst basin filling proceeds to the outlet level dissipated of energy due to considerable flow recirculation during the rising stage of the flood and after overtopping of the outlet are moderated in terms of peak discharge ii can have kinematic waves that are introduced to a flood via hydraulic ponding iii may develop a partitioning of flow regimes for instantaneous peak discharge bed shear stress and froude number due to time transgressive changes in channel cross section specifically between inner channel and overbank regions furthermore normalised change in cross sectional area and normalised change in channel slope can be used to suggest the relative magnitude of instantaneous peak discharge net erosion along a reach can be related to hydraulic persistence above a marker value and net deposition can be related to a time to peak value reconstructions of quaternary outburst floods should consider the importance of including intermediary lakes modern hazard mitigation studies could usefully note the potential use of reservoirs as an outburst flood alleviation resource

lava effusion rates from hand held thermal infrared imagery an example from the june 2003 effusive activity at stromboli a safe easy and rapid method to calculate lava effusion rates using hand held thermal image data was developed during june 2003 at stromboli volcano italy we used a forward looking infrared radiometer flir to obtain images of the active lava flow field on a daily basis between may 31 and june 16 2003 during this time the flow field geometry and size where flows typically a few hundred meters long were emplaced on a steep slope meant that near vertical images of the whole flow field could be captured in a single image obtained from a helicopter hovering at an altitude of 750 m and 1 km off shore we used these images to adapt a thermally based effusion rate method previously applied to low and high spatial resolution satellite data to allow automated extraction of effusion rates from the hand held thermal infrared imagery a comparison between a thermally derived 0 23 0 87 m3 s 1 and dimensionally derived effusion rate 0 56 m3 s 1 showed that the thermally derived range was centered on the expected value over the measurement period the mean effusion rate was 0 38 0 25 m3 s 1 which is similar to that obtained during the 1985 86 effusive eruption and the time averaged supply rate calculated for normal non effusive strombolian activity a short effusive pulse reaching a peak of 1 2 m3 s 1 was recorded on june 3 2003 one explanation of such a peak would be an increase in driving pressure due to an increase in the height of the magma contained in the central column we estimate that this pulse would require the magma column to attain a height of 190 m above the effusive vent which is approximately the elevation difference between the vent and the floor of the ne crater our approach gives an easy to apply method that has the potential to provide effusion rate time series with a high temporal resolution

volcanic hot spot detection from optical multispectral remote sensing data using artificial neural networks summary this paper describes an application of artificial neural networks for the recognition of volcanic lava flow hot spots using remote sensing data satellite remote sensing is a very effective and safe way to monitor volcanic eruptions in order to safeguard the environment and the people affected by such natural hazards neural networks are an effective and well established technique for the classification of satellite images in addition once well trained they prove to be very fast in the application stage in our study a back propagation neural network was used for the recognition of thermal anomalies affecting hot lava pixels the network was trained using the three thermal channels of the advanced very high resolution radiometer avhrr sensor as inputs and the corresponding values of heat flux estimated using a two thermal component model as reference outputs as a case study the volcano etna eastern sicily italy was chosen and in particular the effusive eruption which took place during the month of 2006 july the neural network was trained with a time series of 15 images 12 nighttime images and 3 daytime images and validated on three independent data sets of avhrr images of the same eruption and on two relative to an eruption occurred the following month while for both nighttime and daytime validation images the neural network identified the image pixels affected by hot lava with a 100 percent success rate for the daytime images also adjacentpixelswereincluded apparentlynotinterestedbylavaflow despitetheseperformance differences under different illumination conditions the proposed method can be considered effective both in terms of classification accuracy and generalization capability in particular our approach proved to be robust in the rejection of false positives often corresponding to noisy or cloudy pixels whose presence in multispectral images can often undermine the performance of traditional classification algorithms future work shall address application of the proposed method to data acquired with a high temporal resolution such as those provided by the spinning enhanced visible and infrared imager sensor on board the meteosat second generation geostationary satellite

numerical modeling of lava flow cooling applied to the 1997 okmok eruption comparison with advanced very high resolution radiometer thermal imagery 1 throughout february and march 1997 okmok volcano in the eastern aleutian islands of alaska erupted a 6 km long lava flow of basaltic a a within its caldera in the first part of the study a numerical model for lava flow cooling was developed by patrick et al and applied to the flow to better understand the nature of its cooling in this second part of the study the model predictions for lava surface temperature over a 200 day cooling period were compared to advanced very high resolution radiometer avhrr thermal imagery various methods were used to extract the subpixel lava temperature from the avhrr pixel integrated values including the dual band method and pixel merging inherent to these approaches is the multicomponent modeling of the lava surface temperature whereas active flows have been shown to have several thermal components so too do flows undergoing extended cooling because of the dependence of the methods on the avhrr instantaneous field of view ifov the scan dependent ifov dimensions and overlap values were considered results from patrick et al indicate that convective heat loss from the surface largely controls surface temperature during extended cooling but the functions governing this heat loss mechanism are poorly understood avhrr derived temperatures from this part of the study suggest that values for the convective heat transfer coefficient for this flow were most commonly between 50 and 100 w m 2 k 1 and generally above 25 w m 2 k 1 these results are in agreement with previously measured values from the field but are significantly higher than those assumed in other remote sensing studies of cooling lava also the avhrr data corroborate the modeled prediction of seasonal warming of the lava surface

a field comparison of three pressure difference bedload samplers abstract the movement of bedload over a cross section is often sampled using a pressure difference bedload sampler such as the helley smith whereas several types are in use no one device has gained universal acceptance as the standard for use in all types of streams moreover evidence suggests that similar devices may collect substantially different amounts of bedload because of only slight modifications in design in this study sample weights collected by three types of pressure difference samplers are compared to determine whether differences are statistically significant or whether sampler performance is so irregular and overlapping that one might regard them as being the same the results confirm that the weights of samples collected by the devices are significantly different generally the us blh 84 collected less material the sheetmetal helley smith collected more material and the original helley smith was intermediate these tendencies were consistent at two sites where bedload was measured the implication of these results is that measured transport rates will vary depending on the sampler used and therefore they are not directly comparable without some mode of calibration to place this finding in a larger context sediment rating curves determined from weights of samples and measurements of flow were integrated over available flow records and used to estimate annual yield three estimates of annual yield one for each device were then compared with measures of annual accumulation from a weir pond below one of the collection sites the results indicate that despite differences between the devices data obtained with pressure difference samplers estimated annual accumulations of sediment reasonably well predicted accumulations were within 40 50 of the measured yield for two samplers whereas the third sampler predicted within 80

mesozoic high ba sr granitoids from north china geochemical characteristics and geological implications mesozoic magmatism occurred extensively in the north china block ncb and the dabie sulu orogen dso post dating the north south china collision resulting in abundant intrusive and volcanic rocks ranging from basic to acidic compositions the intermediate acidic intrusive rocks can be grouped into two types namely high ba sr granitoids and low ba sr granitoids that both have distinct geochemical characteristics the high ba sr granitoids are similar in most of the incompatible trace element systematics to the associated basic rocks which probably originated from melting of subcontinental lithospheric mantle indicating significant mantle contributions to them geochemical similarities are observed between the basic rocks from the ncb and dso implying a regional scale magma generating mechanism and that mantle enrichment beneath the dso was independent from the triassic deep continental subduction in the region we therefore interpret that the mesozoic magmatism resulted from delamination of the ancient lithospheric mantle beneath the eastern part of north china

field testing of three bedload samplers efficiency in a gravel bed river spitsbergen abstract a comparative study of the three bedload traps was accomplished to determine the effectiveness differences between the devices the research was carried out in two transverse sections of the proglacial gravel bedded scott river sw svalbard using three devices to perform direct measurements of bedload transport in the river channels several samplers are used for field measurements but none of them has gained widespread acceptance as a standard so far the paper compares transport rates collected in three bedload samplers that differ in structure and functionality i a portable helley smith pressure difference bedload sampler h s ii an anchored river bedload trap rbt and iii the portable sampler used by the polish hydrological services pihm type c all three samplers are constructed using the same components a frame made of thin stainless steel sheet and a nylon bag with the same 2 mm mesh size except pihm measurements were conducted within three consecutive days in two cross sections in the same vertical profiles and at the same time at intervals of 30 and 60 min measurements of bedload transport and water velocity were performed simultaneously in order to determine the effectiveness and representativeness of short term measurements using particular devices the masses of the samples were converted into a specific rate of bedload transport and compared to the results of long term continuous measurement 24 h measurement cycle the results confirm that both specific transport indicators and the mass of the samples collected by the tested devices show a significant variation generally the highest mass and specific transport indicators were obtained using the h s sampler the rbt produced moderate transport rates while the pihm sampler gave the lowest rates the bedload transport rate in a profile estimated on the short term measurements was compared to results of the continuous measurements conducted in the same cross sections in the 7 cases we obtained underestimation to max 10 times and in the next 7 cases overestimation to max 114 times only in four cases were the results of short term measurements similar to the continuous ones the results obtained from the rbt sampler show the smallest variability among all tested devices

post little ice age record of coarse and fine clastic sedimentation in an alaskan proglacial lake many assessments of glacial sediment yield rely solely on mea surements of fine grained suspended sediment we show that sus pended sediment contributes 20 of the total clastic sediment discharge into iceberg lake an alaskan proglacial lake drainage of this lake in 1999 exposed outcrops of varved lacustrine sediment that record suspended sediment deposition since a little ice age highstand two centuries ago lake level has dropped in four abrupt spillway controlled events that are recorded stratigraphically as transient increases in the basinwide deposition of unusually fine grained sediments varve counting constrains ages of these events and hence of each abandoned shoreline and associated delta vol umes of deltaic and lake floor sediments constrain specific yields from four multidecadal intervals between a d 1825 and 1999 to tal yield ranges from 3 8 to 4 9 3 10 3 t km 22 yr 21 and most of the sediment 81 86 is sand and gravel now in the deltas a range of evidence suggests that sediment yield faithfully records up stream sediment production in this small 66 km 2 and heavily gla cierized basin implying an effective subglacial erosion rate of 1 6 mm yr these data show that estimates of total yield based upon suspended sediment alone are subject to large errors and suggest that quarrying accounts for a large fraction of the glacial erosion in this system

sediment sources spatiotemporal variability and rates of fluvial bedload transport in glacier connected steep mountain valleys in western norway erdalen and bodalen drainage basins abstract contemporary fluvial bedload transport rates are still very difficult to measure and as a result of this in many sites only quantitative data on suspended and solute transport are included in sediment budget studies carried out for defined drainage basin systems the presented analysis of fluvial bedload dynamics in different defined subsystems of the glacier connected erdalen 79 5 km 2 and bodalen 60 1 km 2 drainage basins in the steep fjord landscape of western norway provides insights into i detectable relevant sediment sources ii instream channel storage of bedload material iii spatiotemporal variability and controls of bedload transport rates and bedload yields and iv the absolute and relative importance of fluvial bedload transport within the sedimentary budgets of these steep cold climate mountain valleys rockfalls snow avalanches stream channel bank erosion and fluvial transfers through small tributaries draining slope systems are relevant sediment sources for fluvial bedload transport in the main stream channels whereas the main outlet glaciers in both drainage basins are not of importance as all bedload material delivered directly from these outlet glaciers is trapped within proglacial lakes narrow valleys within both drainage basin systems are characterized by a higher intensity of slope channel coupling and display higher rates of sediment supply from slopes into the main stream channels than wider valleys snow avalanches are the most important sediment source in erdalen whereas fluvial transfers through small tributaries followed by snow avalanches are most important in bodalen longer term instream channel storage is not of great importance in the steep bodalen drainage basin but currently plays an important role within the erdalen drainage basin which is characterized by a stepped longitudinal main valley bottom profile favoring deposition of bedload material within less steep main channel reaches the mean annual bedload yields 2010 2013 are 2 4 t km 2 y 1 for the entire erdalen and 13 3 t km 2 y 1 for the entire bodalen drainage basin which are comparably low values for steep and partly glacierized drainage basin systems because of supply limited conditions the intensity of fluvial bedload transport is generally much more related to the availability of sediments than to channel discharge fluvial bedload transport accounts for about one third of the total fluvial transport and accordingly plays an important role within the sedimentary budgets of both drainage basin systems

spatial variations in lava flow field thermal structure and effusion rate derived from very high spatial resolution hyperspectral mivis data 1 high spatial resolution hyperspectral measurements of volcanic thermal anomalies allow for an unconstrained solution of a two component thermal model this can be used for identification of lava flow emplacement style and the calculation of lava flow heat and volume flux the multispectral infrared and visible imaging spectrometer mivis is an airborne sensor equipped with 72 bands in the short infrared range and 10 bands in the thermal infrared region of the spectrum we used mivis acquired for mount etna italy during the july august 2001 eruption to solve the dual band equations in an unconstrained fashion using three bands of unsaturated data our results suggest a complex thermal structure for etnean lava flows this is characterized by a downflow transition from a lightly crusted active channel to a more heavily crusted distal section both surrounded by zones of stagnant cooling flow where exposed molten material is absent and maximum temperatures are thus lower the total flow field effusion rate obtained for 29 july 2001 0700 local time of 8 16 m3 s is in excellent agreement with that obtained from ground based measurements and advanced very high resolution radiometer data flow by flow effusion rates obtained from the mivis data vary depending on whether the vent is linked to the central conduit or the dyke that was injected from greater depth as well as vent elevation with lower elevation vents experiencing higher effusion rates

the changing morphology of an open lava channel on mt etna an open channel lava flow on mt etna sicily was observed during may 30 31 2001 data collected using a forward looking infrared flir thermal camera and a minolta land cyclops 300 thermal infrared thermometer showed that the bulk volume flux of lava flowing in the channel varied greatly over time cyclic changes in the channel s volumetric flow rate occurred over several hours with cycle durations of 113 190 min and discharges peaking at 0 7 m3 s 1 and waning to 0 1 m3 s 1 each cycle was characterized by a relatively short high volume flux phase during which a pulse of lava with a well defined flow front would propagate down channel followed by a period of waning flow during which volume flux lowered pulses involved lava moving at relatively high velocities up to 0 29 m s 1 and were related to some change in the flow conditions occurring up channel possibly at the vent they implied either a change in the dense rock effusion rate at the source vent and or cyclic variation in the vesicle content of the lava changing its bulk volume flux pulses would generally overspill the channel to emplace p hoehoe overflows during periods of waning flow velocities fell to 0 05 m s 1 blockages forming during such phases caused lava to back up occasionally backup resulted in overflows of slow moving a that would advance a few tens of meters down the levee flank compound levees were thus a symptom of unsteady flow where overflow levees were emplaced as relatively fast moving p hoehoe sheets during pulses and as slow moving a units during backup small localized fluctuations in channel volume flux also occurred on timescales of minutes volumes of lava backed up behind blockages that formed at constrictions in the channel blockage collapse and or enhanced flow under around the blockage would then feed short lived wave like down channel surges real fluctuations in channel volume flux due to pulses and surges can lead to significant errors in effusion rate calculations

an empirical function to estimate the depths of linear hot sources laboratory modeling and field measurements of lava tubes estimating depths of buried lava tubes is important for determining the thermal budgets and effusion rates of basaltic volcanic systems this research used a laboratory experiment scaled to a lava tube system to measure the 3d temperature field surrounding a hot viscous fluid flowing through a buried glass tube while varying conditions such as flow rate and temperature the depth of the glass tube was changed for different experimental runs numerical techniques were applied to model the laboratory experiment the surface thermal distributions from 166 thermal traverses constrained to a depth to width ratio of 0 6 to 1 6 were analyzed to empirically derive a depth estimation function using regression techniques this linear anomaly surface transect last depth function is a scaleable depth estimation technique which can be solved with thermal imaging data alone the minimum temperature maximum temperature and width of a lorentzian distribution fit to a surface thermal transect are the only inputs required for the last function to estimate the depths of the hot source the input parameters were then applied to non laboratory situations including the kuhio lava tube system in hawai i the last function produced depth estimates of 0 3 m for the kuhio lava tube in hawai i which did not agree with observations on the ground this is the result of the complex composition and geometry of an actual lava tube where heat transfer is controlled by more than a simple fluid filling a tube but also by convection of gasses and fluids in a partially filled passage though not effective for lava tubes at this time the model provides promising results for simple cases applied to engineering and underground coal fires

high resolution measurement of bedload transport a bedload movement detector of novel design was installed in a gravel bed stream as a component of the ongoing research on sediment transport dynamics in the stuart takla experimental watersheds in north central british columbia canada the device is designed to collect information on the patterns and timing of bedload transport during a flood event the device is based on a passive magnetic sensor that produces signals of 10 2 to 10 5 v as its magnetic field is disturbed by passing clasts a series of 82 sensors is housed in an aluminum beam placed across the stream inserted such that its surface is flush with the gravel bed the device can be raised or lowered to compensate for bed aggradation and scour a data acquisition system gathers voltage signals from the sensors at rates of 30 to 100 hz this device is sensitive enough to record the movement of most volcanic metamorphic granitic and ultramafic clasts larger than a few millimetres o ne ell creek watershed is a 68 km2 tributary basin of the middle river drainage system in the northern headwaters of the fraser river bedload transport generally occurs twice a year in the stuart takla streams once during spring floods and again during salmon spawning activity bedload moved only during two days in 1998 at the peak of the relatively small nival flood in may nevertheless the device detected at least 3 106 passing clasts a continuous record of bedload transport was obtained showing a pulsating pattern of activity seemingly independent of stage lateral movement of the transport zone and a sudden onset of bed movement with a tapered cessation we anticipate that more sophisticated calibration of the sensors and accelerated sampling rates will provide detailed information on the size and or velocity and magnetic permeability of particles moving over the device and will contribute to a better understanding of bedload transport copyright 2000 john wiley sons ltd

the morphology of lava flows in planetary environments predictions from analog experiments the rates of surface cooling and lateral spreading are evaluated for lava flows on the surface of earth venus mars the moon and io differences between the flow morphologies expected in these environments are then predicted under the assumption that the results of recent laboratory simulations of lavas using wax extruded beneath cold water fink and griffiths 1990 can be carried over these experiments involved the spreading of viscous liquid under gravity in the presence of a solidifying surface crust and revealed a set of four distinct surface morphologies transitions from one morphology to the next occurred in a well defined sequence when the relative rates of surface solidification and lateral spreading were varied in comparison with subaerial flows on earth the surface of lavas solidifies faster on venus where the dense atmosphere provides additional convective heat transfer lateral flow of lava is much slower under the smaller gravity of the moon hence for a given extrusion rate and viscosity solid crust is predicted to form closer to the vent on both the moon and venus than on earth equivalently faster extrusion rates than those on earth are required on the moon io and venus in order to produce a given surface morphology a comparison of observed structure flow rates and estimated viscosities for some well documented terrestrial lava flows shows reasonable agreement with the predictions of the model extrapolation to extraterrestrial lavas is then illustrated by constraining the effusion rate for a martian lava flow whose composition is assumed spectral information on the chemical composition of martian flows to be sought by the thermal emission spectrometer on the mars observer mission in conjunction with detailed morphologic observations from the mars observer camera could allow much more accurate estimates of effusion rates for martian lavas

lava water interaction and hydrothermal activity within the 2014 2015 holuhraun lava flow field iceland abstract lava that erupted during the 2014 2015 holuhraun eruption in iceland flowed into a proglacial river system resulting in aqueous cooling of the lava and an ephemeral hydrothermal system we carried out a monitoring study of this system from 2015 to 2018 to document the cooling of the lava over this time using thermocouple measurements and data logging sensors the heat loss rate from advection through this hydrothermal system in august 2015 was 5 5 108 w since eruption aqueous cooling likely accounted for 1 of the total heat loss from the lava this estimate excludes steam losses from fumaroles as well as any groundwater that was not released to the surface and thus is a lower bound near the terminus of the flow advection of heat by flowing water may have locally accounted for tens of percent of the total cooling of that part of the flow our data quantify the importance of water cooling for this lava flow and can be compared with models to better understand lava water interactions more generally we also provide detailed methods for simple low cost monitoring of similar instances in the future

the influence of wind on the estimation of lava effusion rate from thermal remote sensing effusion rate is a key parameter to model lava flow advance and associated risks estimation of effusion rate from thermal remote sensing using satellite data has matured to the point where it can be an operational monitoring tool notably for volcanoes without a ground observatory however robust physical models as required for quantitative interpretations have not yet been adequately developed the current and widely used method relates the satellite measured radiated power to the flow effusion rate through the lava area with an empirical fit that assumes a low surface cooling efficiency here we use novel fluid dynamic laboratory experiments and viscous flow theory to show that assuming low convective cooling at the surface of the flow leads to a systematic underestimation of the effusion rate this result obtained for the case of a hot isoviscous gravity current which cools as it flows relies only on the respective efficiency of convection and radiation at the flow surface and is independent of the details of the internal flow model applying this model to lava flows cooling under classical wind conditions we find that the model compares well to data acquired on basaltic eruptions within the error bars corresponding to the uncertainties on natural wind conditions hence the thermal proxy deduced from the isoviscous model does not seem to require an additional fitting parameter accounting for internal flow processes such as crystallization the predictions of the model are not correct however for thick lava flows such as highly viscous domes because a thermal steady state is probably not reached for these flows furthermore in the case of very large basaltic flows extra cooling is expected due to self induced convection currents the increased efficiency of surface cooling for these large eruptions must be taken into account to avoid a gross and dangerously misleading underestimate of the effusion rate

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

sediment export transient landscape response and catchment scale connectivity following rapid climate warming and alpine glacier recession abstract in the face of rapid climate warming rapid glacier recession should lead to a marked increase in the spatial extent of the paraglacial zone in glaciated drainage basins the extent of the paraglacial zone has been well established to be transient but there are very few studies of this transient response and what it means for sediment export there is good reason to expect that glacier recession could increase basin scale sediment connectivity as sediment becomes less dependent on glacier surface transport proglacial streams are more able to migrate laterally than subglacial streams and so access sediment for transport and glacier debuttressing may aid the development of gullies that can dissect moraines and so aid hillslope to proglacial zone connectivity by using records of the flushing of hydroelectric power installations we were able to develop a record of coarse sediment sand and gravel export from a basin with a rapidly retreating valley glacier the haut glacier d arolla from 1977 to 2014 modelling suggested that these data could only be partially controlled by transport capacity implying an important role for sediment supply and potentially for the influence of changing sediment connectivity indeed there was evidence of the effects of glacial debuttressing upon gullying processes and hence a possible increase in the ease of connection of upstream basins to the proglacial area more recently we were able to show possible temperature control on sediment export which may only have become apparent because of the progressive development of better sediment connectivity however whilst rapid glacier recession should result in theory in a progressive increase in connectivity of sediment sources to the basin outlet the supply to capacity ratio does not increase continually with glacier recession until maximum capacity is reached we identified two possible examples of why first gullying was also accompanied by the sediment accumulation at the base of moraines that was too coarse to be transported by the proglacial stream maintaining disconnection of the upper basins second the sediment capacity ratio appeared to be elevated during periods of more rapid retreat and we attribute this to the importance of a continued supply of unworked glacial till before fluvial reworking and sorting of freshly exposed sediment increased the resistance of sediment to entrainment and hence export rates thus the transient geomorphic response of glaciated basins to glacier recession may involve negative feedbacks that can reduce the extent to which increases in connectivity elsewhere in the basin lead to increased sediment export

transient self potential anomalies associated with recent lava flows at piton de la fournaise volcano reunion island indian ocean self potential signals are sensitive to various phenomena including ground water flow streaming potential thermal gradients thermoelectric potential and potentially rapid fluid disruption associated with vaporization of water we describe transient self potential anomalies observed over recent 9 years lava flows at piton de la fournaise volcano reunion island indian ocean repeated self potential measurements are used to determine the decay of the self potential signals with time since the emplacement of a set of lava flow we performed a 9 km long self potential profile in february 2004 in the grand brule area this profile was repeated in july august 2006 the second repetition of this profile crossed eight lava flows emplaced between 1998 and 2005 during seven eruptions of piton de la fournaise volcano the self potential data show clear positive anomalies up to 330 mv and spatially correlated with the presence of recent lava flows the amplitude of the self potential anomalies decreases exponentially with the age of the lava flows with a relaxation time of not vert similar 44 months we explain these anomalies by the shallow convection of meteoric water and the associated streaming potential distribution but we cannot exclude possible contributions from the thermoelectric effect and the rapid fluid disruption mechanism this field case evidences for the first time transient self potential signals associated with recent volcanic deposits it can be also a shallow analogue to understand the variation of self potential signals in active geothermal areas and transient self potential signals associated with dike intrusion at larger depths the empirical equation we proposed can also be used to diagnose the cooling of recent lava flow on shield volcanoes

a general model of paraglacial landscape response a unifying attribute of all forms of paraglacial response is that deglaciation results in the exposure of unstable or metastable sediment sources that are subsequently tapped by a wide variety of processes over a wide range of timescales the paraglacial period in different geomorphological contexts is therefore con ditioned by two variables glacially conditioned sediment release and rate of sediment reworking under steady state conditions the latter may be approximated by an exhaustion model in which sediment yield is related to the amount of remaining available sediment by a negative exponential function this model offers an approximation for the behaviour of primary paraglacial systems in which glacigenic sediment sources are not replenished the long term behaviour of secondary primarily uvial paraglacial systems in which sediment inputs include both in situ and reworked glacigenic sediment appears intrinsically more complex but consistent with an exhaustion model if initial sediment avai

pāhoehoe flow cooling discharge and coverage rates from thermal image chronometry 1 theoretically and empirically derived cooling rates for active p hoehoe lava flows show that surface cooling is controlled by conductive heat loss through a crust that is thickening with the square root of time the model is based on a linear relationship that links log time with surface cooling this predictable cooling behavior can be used assess the age of recently emplaced sheet flows from their surface temperatures using a single thermal image or image mosaic this allows quantification of the variation in areal coverage rates and lava discharge rates over 48 hour periods prior to image capture for p hoehoe sheet flow at k lauea hawai i this gives coverage rates of 1 5 m2 min at discharge rates of 0 01 0 05 m3 s increasing to 40 m2 min at 0 4 0 5 m3 s our thermal chronometry approach represents a quick and easy method of tracking flow advance over a three day period using a single thermal snap shot

continuous measurements of bedload transport rates in a small glacial river catchment in the summer season spitsbergen abstract the study on bedload transport was conducted on the gravel bed scott river catchment with a glacial alimentation regime located in the nw part of the wedel jarlsberg land spitsbergen with subpolar climatic conditions in the melt season of 2010 bedload transport rate was continuously monitored at 24 hour intervals by means of four river bedload trap devices aligned across the width of the channel the maximum bedload transport rate varied strongly at portions of the cross section from 16 to 152 kg m 1 d 1 in cross profile i c p i and 4 to 125 kg m 1 d 1 in cross profile ii c p ii the maximum channel mean bedload transport rate qa amounted to 54 kg m 1 d 1 c p i and 35 kg m 1 d 1 c p ii mean daily bedload discharge qb was estimated at a level of 97 kg day 1 c p i and 35 kg m 1 d 1 c p ii and the total bedload yield was determined at approx 4345 kg in the measurement period 2086 kg c p i 2203 kg c p ii from 13 07 to 10 08 the analysis of the relationship between channel mean bedload transport rate and water velocity or shear stress revealed a significant value of the correlation coefficient r2 0 6 discharge and rate of bedload transport were dependent on the weather and number of days with flood discharge approx 58 of the entire discharged bedload was transported during 3 violent ablation precipitation floods bedload grain size distribution was right skewed and showed moderate sorting

emplacement and inflation of pahoehoe sheet flows observations and measurements of active lava flows on kilauea volcano hawaii inflated pahoehoe sheet flows have a distinctive horizontal upper surface which can be several hundred meters across and are bounded by steep monoclinal uplifts the inflated sheet flows we studied ranged from 1 to 5 m in thickness but initially propagated as thin sheets of fluid pahoehoe lava generally 20 30 cm thick individual lobes originated at outbreaks from the inflated front of a prior sheet flow lobe and initially moved rapidly away from their source velocities slowed greatly within hours due to radial spreading and to depletion of lava stored within the source flow as the outward flow velocity decreases cooling promotes rapid crustal growth at first the crust behaves plastically as pahoehoe toes form after the crust attains a thickness of 2 5 cm it behaves more rigidly and develops enough strength to retain incoming lava thus increasing the hydrostatic head at the flow front the increased hydrostatic pressure is distributed evenly through the liquid lava core of the flow resulting in uniform uplift of the entire sheet flow lobe initial uplift rates are rapid flows thicken to 1 m in 1 2 hours but rates decline sharply as crustal thickness increases and as outbreaks occur from the margins of the inflating lobe one flow reached a final thickness of nearly 4 m after 350 hr inflation data define power law curves whereas crustal cooling follows square root of time relationships the combination of data can be used to construct simple models of inflated sheet flows as the flow advances preferred pathways develop in the older portions of the liquid cored flow these pathways can evolve into lavatube systems within a few weeks formation of lava tubes results in highly efficient delivery of lava at velocities of several kilometers per hour to a flow front that may be moving 1 2 orders of magnitude slower if advance of the sheet flow is terminated the tube remains filled with lava that crystallizes in situ rather than draining to form the cave like lava tubes commonly associated with pahoehoe flows inflated sheet flows from kilauea and mauna loa are morphologically similar to some thick icelandic and submarine sheet flows suggesting a similar mechanism of emplacement the planar sheet like geometry of flood basalt flows may also result from inflation of sequentially emplaced flow lobes rather than nearly instantaneous emplacement as literal floods of lava

the initial cooling of pahoehoe flow lobes in this paper we describe a new thermal model for the initial cooling of pahoehoe lava flows the accurate modeling of this initial cooling is important for understanding the formation of the distinctive surface textures on pahoehoe lava flows as well as being the first step in modeling such key pahoehoe emplacement processes as lava flow inflation and lava tube formation this model is constructed from the physical phenomena observed to control the initial cooling of pahoehoe flows and is not an empirical fit to field data we find that the only significant processes are a heat loss by thermal radiation b heat loss by atmospheric convection c heat transport within the flow by conduction with temperature and porosity dependent thermal properties and d the release of latent heat during crystallization the numerical model is better able to reproduce field measurements made in hawai i between 1989 and 1993 than other published thermal models by adjusting one parameter at a time the effect of each of the input parameters on the cooling rate was determined we show that a the surfaces of porous flows cool more quickly than the surfaces of dense flows b the surface cooling is very sensitive to the efficiency of atmospheric convective cooling and c changes in the glass forming tendency of the lava may have observable petrographic and thermal signatures these model results provide a quantitative explanation for the recently observed relationship between the surface cooling rate of pahoehoe lobes and the porosity of those lobes jones 1992 1993 the predicted sensitivity of cooling to atmospheric convection suggests a simple field experiment for verification and the model provides a tool to begin studies of the dynamic crystallization of real lavas future versions of the model can also be made applicable to extraterrestrial submarine silicic and pyroclastic flows

constraints on determining the eruption style and composition of terrestrial lavas from space the surface temperatures of active lavas relate to cooling rates chemistry and eruption style we analyzed 61 hyperspectral satellite images acquired by the national aeronautics and space administration s earth observing 1 eo 1 hyperion imaging spectrometer to document the surface temperature distributions of active lavas erupted at 13 volcanoes images were selected to encompass the range of common lava eruption styles specifi cally lava fountains fl ows lakes and domes our results reveal temperature distributions for terrestrial lavas that correlate with composition i e a statistically signifi cant difference in the highest temperatures retrieved for mafi c lavas and intermediate and felsic lavas and eruption style maximum temperatures observed for mafi c lavas are 200 c higher than for intermediate and felsic lavas all eruption styles exhibit a low temperature mode at 300 c lava fountains and a a flows also exhibit a higher temperature mode at 700 c the observed differences between the temperatures are consistent with the contrasting rates at which the lava surfaces are thermally renewed eruption styles that allow persistent and pervasive thermal renewal of the lava surface e g fractured crusts on channel fed a a flows exhibit a bimodal temperature distribution eruption styles that do not e g the continuous skin of pahoehoe lavas exhibit a single mode we conclude that insights into composition and eruption style can only be gained remotely by analyzing a large spatio temporal sample of data this has implications for determining composition and erup tion style at the jovian moon io for which no in situ validation is available

bedload component of glacially discharged sediment insights from the matanuska glacier alaska the flux of glacially derived bedload and the proportions of the suspended and bedload components carried by proglacial streams are highly debated published data indicate a large range from 30 to 75 in the bedload percentage of the total load two vents where supercooled subglacial meltwater and sediment are discharged were sam pled over the course of an entire melt season in order to quantify the flux of glacially delivered bedload at the matanuska glacier alaska the bedload component contributed by these vents for the one melt season monitored is negligible furthermore the bedload fluxes appear to be strongly supply limited as shown by the poorly correlated discharge bedload flux magnitude and grain size caliber thus in this case any attempt to employ a predictive quantitative expression for coarse sediment production based on discharge alone would be inaccurate a nonglaciated basin proximal to the matanuska glacier ter minus yielded higher bedload sediment fluxes and larger clast sizes than delivered by the two monitored vents such nonglaciated basins should not be overlooked as potentially major sources of coarse bedload that is reworked and incorporated into valley outwash usually subequal although bedload may range from 30 to 75 of the total clastic load establishing portable relationships between suspended load bedload and discharge would enhance our understanding of how and when glaciers erode for the melt season studied we show that bedload is 1 of the total clastic load and does not have any obvious correla tion to discharge at two of the main vents at the terminus of the matanuska glacier alas ka these observations coupled with high measured bedload component of adjacent non glaciated valleys inspire several working hy potheses for the observed origin of coarse bedload in the matanuska river downstream of the ice margin

the nahal yatir bedload database sediment dynamics in a gravel bed ephemeral stream the nahal yatir bedload transport database arises from the northern negev river sediment monitoring programme and represents the first body of bedload information to be collected during flash floods in desert gravel bed streams bedload flux was established automatically with three slot samplers of the birkbeck type this was complemented by hydraulic measurements that allow sediment transport to be rated against channel average shear stress and specific stream power bed material and bedload grain size distributions are also provided the database is given in both printed and electronic tabular format

role of heat advection in a channeled lava flow with power law temperature dependent rheology 1 the cooling of a lava flow both in the transient and the steady state is investigated considering that lava rheology is pseudoplastic and dependent on temperature lava exits from the vent with constant velocity and flows down a slope under the effect of gravity force inside a channel of rectangular cross section we consider that cooling of lava is caused by thermal radiation into the atmosphere and thermal conduction at the channel walls and at the ground the heat equation is solved numerically in a 3 d computational domain and the solution is tested to evaluate the numerical errors we study the steady state and the initial transient period of lava cooling results indicate that the advective heat transport significantly modifies the cooling rate of lava slowing down the cooling process since the lava velocity depends on temperature the cooling rate depends on the effusion temperature velocity profiles are modified during cooling showing two marginal static zones where the crust can form and remain stable the fraction of crust coverage is calculated under the assumption that the solid lava is a plastic body with temperature dependent yield strength we numerically confirm that heat advection cannot be neglected in the mechanism of formation of lava tubes

bedload transport measurements at the erlenbach stream with geophones and automated basket samplers in the erlenbach stream a pre alpine steep channel in switzerland sediment transport has been monitored for more than 25 years near the confluence with the main valley river stream flow is monitored and sediment is collected in a retention basin with a capacity of about 2000 m3 the basin is surveyed at regular intervals and after large flood events in addition sediment transport has been continuously monitored with piezoelectric bedload impact and geophone sensors since 1986 in 2008 2009 the measuring system in the erlenbach stream was enhanced by installing an automatic system to obtain bedload samples movable metal baskets are mounted on a rail at the downstream wall of the large check dam above the retention basin and they can be moved automatically into the flow to take bedload transport samples the wire mesh of the baskets has a spacing of 10 mm to sample all sediment particles coarser than this size which is about the limiting grain size detected by the geophones the upgraded measuring system permits to obtain bedload samples over short sampling periods and to measure the grain size distribution of the transported material and its variation over time and with discharge the analysis of calibration relationships for the geophone measuring system confirms findings from very similar measurements which were performed until 1999 with piezoelectric bedload impact sensors there is a linear relationship between impulse counts and bedload mass passing over the sensors findings from flume experiments are used to discuss the most important factors which affect the calibration of the geophone signal the bedload transport rates as measured by the moving baskets are among the highest measured in natural streams with values of the order of several kilograms per meter per second copyright 2012 john wiley sons ltd

assessment of sediment sources throughout the proglacial area of a small arctic catchment based on high resolution digital elevation models abstract the article presents calculations of quantitative modifications of the morphology of selected subsystems of a glacial valley through i identification of the spatial distribution of important sources of sediment ii assessment of the spatiotemporal variety of sediment volume and landform morphology and iii assessment of the role of particular subsystems in sediment distribution the study involved a comparison of the results of field measurements from 2010 to 2013 performed in the scott glacier catchment 10 1 km2 in nw wedel jarlsberg land spitsbergen the assessment of the landform surface changes was performed by means of a precise terrestrial laser scanning tls survey the applied field and post processing techniques for oblique laser scanning permitted the acquisition of digital elevation data at a resolution 0 01 m and density 500 pt m 2 this allowed the development of a detailed terrain model and balancing spatial quantitative changes in six research test areas 10 000 m2 located within two subsystems of the catchment in a cascade arrangement in the alluvial valley floor subsystem the survey covered 1 the glacier terminus 2 the intramarginal outwash plain 3 the extramarginal braid plain and 4 the alluvial fan and in the slope subsystem 5 the erosional depositional slope in the gorge through terminal moraines and 6 the solifluction slope three zones differing in terms of the spatiotemporal dynamics of geomorphic processes were distinguished within the two analysed valley subsystems in the valley floor subsystem these are i the zone of basic supply distribution throughout the melting season and ii the redeposition zone distribution particularly during floods and in the slope subsystem iii zone of periodical supply distributed mainly in periods of increased precipitation and rapid increases in temperature in summer and during snow avalanches in winter the glacier and the landforms of the channel and valley floor as well as slope sediments transported as a result of mass wasting processes and activity of the active permafrost layer constitute important sources of sediment supply over a short 3 year timescale evidence of major changes of the surface morphology slopes floodplain and channel platform resulted in varied sediment budgets the subtraction of consecutive dems of the test areas located in the alluvial valley subsystem revealed downstream spatial and volumetric differentiation from the predominance of erosion 79 of volume 43 of area to the dominance of deposition 90 91 respectively in upper part of the valley floor to erosion predominance in the central 88 95 and lower 87 82 part of valley floor the test areas located on the slope subsystem showed the opposite relationship deposition dominance 88 of volume 80 of area in the upper gorge and erosion dominance 99 99 respectively in the lower part solifluction slopes the analysis of short time repeated surveys 3 week survey where volumes were calculated following dem subtraction showed increased deposition 82 of volume 79 of area for the alluvial fan and for solifluction slopes 70 57 respectively

observations of the effect of wind on the cooling of active lava flows 1 we present the first direct observations of the cooling of active lava flows by the wind we confirm that atmospheric convective cooling processes i e the wind dominate heat loss over the lifetime of a typical pahoehoe lava flow in fact the heat extracted by convection is greater than predicted especially at wind speeds less than 5 m s and surface temperatures less than 400 c we currently estimate that the atmospheric heat transfer coefficient is about 45 50 w m 2 k 1 for a 10 m s wind and a surface temperature 500 c further field experiments and theoretical studies should expand these results to a broader range of surface temperatures and wind speeds

the hydrochemistry of bayelva a high arctic proglacial stream in svalbard major ion silica and ph data from a high arctic proglacial stream network are examined factor analysis shows that the major controls upon hydrochemistry in the basin include snowpack solute elution rapid alteration of minerals via surface reactions and slow incongruent silicate dissolution the importance of chemical weathering is found to increase downstream at the expense of solute acquisition from the transient snowpack data from a series of snow pits show that snowpack solute elution is characterised by the preferential elution of so42 evidence for the preferential elution of no3 is equivocal however no3 levels in proglacial runoff may be enhanced by the leaching of cryotic soils later in the ablation season chemical weathering is dominated by calcite dissolution at high elevations and a combination of calcite and dolomite dissolution in the downstream proglacial environment silicate weathering at high elevations is characterised by the enrichment of k relative to si concentrated active layer soil waters show less enrichment of k and constitute a potentially important source of dissolved silica to the river system na is also produced by silicate weathering but its mobility is believed to be largely governed by ion exchange with ca2 early in the ablation season all chemical weathering environments are characterised by high p co2 due to either respiration within the soil or at higher elevations within the catchment h provision from acid aerosol and sulphide oxidation however rates of sulphide oxidation are limited because the cold based thermal regime of the glaciers effectively prevents access of meltwaters to freshly comminuted sub glacial sulphide minerals the restricted sub glacial weathering therefore means that ice marginal and proglacial environments are the most important zones of solute acquisition by meltwaters causing significant enrichment of major ions silica and dissolved co2 within only a short distance of the contemporary ice margin

spatio temporal evolution of temperature and fluid flow through a new thermo lithological boundary the case of a pit crater of karthala volcano comoros archipelago refilled on january 13th 2007 by a lava flow on january 13 th 2007 the effusive eruption of karthala volcano in the comoros islands emitted a lava flow which has been perfectly constrained inside the cylindrical shape of the choungou chagnoumeni pit crater 225m in diameter and with a thickness of about 7m the good knowledge of the geometry of this lava flow allowed modeling its cooling with the rheolef code with a good accuracy the results of the thermal modeling were compared with other measurements performed on the field 1 a high resolution electrical resistivity tomography profile crossing the boundary of the crater and 2 the thermal monitoring of temperature with eleven sensors spaced 1 meter apart at 30 cm depth perpendicularly to the boundary of the crater thanks to this multidisciplinary approach it has been possible to display that in the first order the resistivity distribution in the soil 2 years and 5 months after the eruption is directly influenced by the residual temperature and not by the structural boundary during the first three years of cooling an inversion in the shallow lateral temperature gradient was observed in temperature data set collected at 30 cm depth

reappraisal of the ages of neoproterozoic strata in south china no connection with the grenvillian orogeny the jiangnan fold belt separates the yangtze and cathaysia blocks in south china and has long been considered grenvillian in age in order to place south china in central rodinia it consists of deformed early neoproterozoic strata that are unconformably overlain by undeformed late neoproterozoic strata and intruded by undeformed and unmetamorphosed granitic plutons zircons from the early neoproterozoic strata yield u pb ages as young as 830 ma and one granitic pluton has a zircon u pb age of ca 827 ma the 830 ma mafic rocks along the southeastern margin of the yangtze block have arc affinity geochemical characters whereas mafic rocks younger than 830 ma have typical ocean island basalt oib like compositions thus we suggest that the early neoproterozoic strata were deposited on an active continental margin prior to amalgamation of the yangtze and cathaysia blocks at ca 830 ma the overlying late neoproterozoic strata were deposited in the intracontinental rifted nanhua basin at 820 730 ma and probably reflect backarc spreading above the long lived 950 735 ma oceanic subduction zone along the northern and western margin of the yangtze block this model is consistent with the secular tectonic evolution of south china during the neoproterozoic the jiangnan fold belt is therefore not a grenvillian feature as previously suggested and there is no evidence to place south china in central rodinia instead we believe that south china was located in a marginal position relative to this supercontinent

modeling the lava heat flux during severe effusive volcanic eruption an important impact on surface air quality the april 2007 eruption of piton de la fournaise one of the most active volcanoes in the world was the strongest eruption in recent decades with 230mm3 of lava emitted and more 300kt of so2 degased the surface concentrations of so2 have been measured by the ora air observatory of the reunion island and showed that many stations exceeded the critic threshold for health these high concentrations led to important health issues accompanied by environmental and infrastructure degradations realized with mesonh atmospheric model our simulations show the transport of sulfur and his component between 2 april and 6 april 2007 with a focus on the influence of heat flow from lava for this purpose we have implemented forefire a surface model initially realized to simulate forest fire by adapting it to reproduce the dynamic of a lava flow thus all flows so2 heat vapor co2 co are triggered depending on its dynamic with this first approach our simulations reproduce quite faithfully the surface field observation of so2 provides by ora various sensitivity analyzes exhibit that volcano sulfur distribution was mainly controlled by the lava heat flow without heat flow parameterization the surface concentrations are multiplied by a factor 30 compared to the reference simulation simulations also put in evidence that the 5 april during the height of the eruption changes in meteorological conditions especially weakening of atmospheric boundary layer stability led to various pollutants to be transported in higher altitude 8000m the main consequence is the volcanic pollutants are transported off the east coast of reunion island

magnitude and frequency in proglacial rivers a geomorphological and sedimentological perspective abstract proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments this paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective the nature of the meltwater inputs can be characterised as low magnitude high frequency primarily controlled by ablation inputs from the source glacier or high magnitude low frequency primarily controlled by exceptional inputs the most important high magnitude low frequency inputs are catastrophic outburst floods often referred to by the term jokulhlaup icelandic for glacier burst glacier surges are an additional form of cyclical variation impacting the proglacial environment which briefly alter the volumes and patterns of meltwater input the sedimentary consequences of low magnitude high frequency discharges are related to frequent variations in stage the greater directional variability that sediment will record and the increased significance of channel confluence sedimentation in contrast the most significant characteristics of high magnitude low frequency flooding include the presence of large flood bars and mid channel jokulhlaup bars hyperconcentrated flows large gravel dunes and the formation of ice block kettle hole structures and rip up clasts glacier surges result in a redistribution of low magnitude high frequency processes and products across the glacier margin and small floods may occur at the surge termination criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics studies of quaternary proglacial fluvial sediments are used to determine how the interaction of the various magnitude and frequency regimes might produce a distinctive sedimentary record consideration of sandur architecture and stratigraphy shows that the main controls on the sedimentary record of proglacial regions are the discharge magnitude and frequency regime sediment supply the pattern of glacier advance or retreat and proglacial topography a model of sandur development is suggested which shows how discharge magnitude and frequency in combination with sandur incision and aggradation controlled by glacier advance and retreat can control sandur stratigraphy

suspended sediment yield and transfer processes in a small high arctic glacier basin svalbard observations of suspended sediment concentration and discharge at two sites on the proglacial river network draining from a predominantly cold based high arctic glacier austre broggerbreen are described analysis of these observations illustrates i the relatively low suspended sediment yield from this basin in comparison with many other glacier basins reported in the open literature ii sustained and possibly increasing availability of suspended sediment to the fluvial system as the ablation season progresses and iii the role of the proglacial sandur as both a sediment source and sink field observations coupled with the results of the data analysis are used to make inferences concerning the changing nature and relative importance of sediment sources within the basin 1998 john wiley sons ltd

combining impact sensor field and laboratory flume measurements with other techniques for studying fluvial bedload transport in steep mountain streams the timing and rate of fluvial bedload transport are of central importance within sediment budget studies and in many applications in river science and engineering during the years 2010 2011 and 2012 detailed field measurements with portable impact sensors as a non invasive technique for indirectly determining fluvial bedload transport intensity were conducted in two instrumented and supply limited drainage basin systems erdalen and bodalen in the fjord landscape in western norway additional field measurements with portable impact sensors were carried out in 2010 and 2011 in selected transport limited fluvial systems in the coast mountains of western canada the collected impact sensor field data were calibrated with laboratory flume experiments the data from the impact sensor field measurements in western norway and the flume experiments were combined with field data from continuous discharge monitoring repeated surveys of channel morphometry and sediment texture particle tracer measurements helley smith samplings underwater video filming and biofilm analyses the combination of methods and techniques applied provides insights into the temporal variability and intensity of fluvial bedload transport in the selected mountain streams i in the transport limited systems with generally high bedload transport rates during high discharge and with bedload material moving in clusters over the impact sensor plates impact sensor data based on a 1 s measuring interval provide the opportunity to detect the start and end of bedload transport thus to identify discharge thresholds for sediment entrainment and to roughly estimate the intensity and relative intensity of change of bedload transport during the measuring period ii in the supply limited systems with low bedload transport rates and bedload components moving separately as single particles over the impact sensor plates impact sensor data with a 1 s measuring interval allow the detection of the start and end of transport of bedload components 11 3 mm thus the identification of discharge thresholds for possible entrainment of particles the quantification of the number of particles 11 3 mm moving over the impact sensor plates during the measuring period the rough estimation of grain sizes of the particles moving separately over the impact sensor plates and the calculation of the total mass of the bedload material 11 3 mm moving over the impact sensor plates during the measuring period iii when combined with other methods and techniques helley smith sampling particle tracer measurements biofilm analyses underwater video filming which provide information on the active bedload transport channel width on discharge thresholds for possible entrainment of particles of different grain sizes and on transport rates of bedload material 11 3 mm total rates of fluvial bedload transport covering all given grain sizes of the bedload material can be calculated for the supply limited mountain streams with generally low bedload transport the higher measured annual bedload yield in bodalen 13 6 t km 2 yr 1 compared to erdalen 2 6 t km 2 yr 1 reflects a higher level of slope channel coupling in bodalen than in erdalen

hydrothermal fluid flow disruptions evidenced by subsurface changes in heat transfer modality the la fossa cone of vulcano italy case study detecting volcanic unrest is of primary importance for eruption forecasting especially on volcanoes characterized by highly dangerous and often seemingly unpredictable phreatic or phreatomagmatic eruptions we present a simple and innovative analysis of shallow vertical temperature profiles to depths of 70 cm these data were recorded at la fossa cone of vulcano aeolian islands italy during an episode of increased hydrothermal and seismic activities that occurred between september and december 2009 this work involves the use of the coefficient of determination r 2 on vertical temperature profiles in order to identify changes in conductive versus convec tive heat transfer modality the increase in convective heat transfer can be related to the disruption of the hydrothermal system due to its pressurization and or variation of ground permeability between the hydrothermal system and the surface while raw temperature data do not evidence any significant variation during the period investigated and the classic temperature gradient is highly influenced by seasonal variations the fluctuation of r 2 displayed striking spikes that coincided with the seismic swarm inside the volcanic edifice such a low cost device associated with easy real time data processing could constitute a very promising yet deceptively simple technique to monitor hydrothermal systems in order to assess the hazard posed by high energy eruptions for populations living close to active volcanoes

using sediment impact sensors to improve the morphological sediment budget approach for estimating bedload transport rates constructing a sediment budget from morphological channel change typically measured using repeat cross sectional surveys has proven a useful technique for estimating mean bedload transport rates in gravel bed rivers we apply and suggest improvements to the approach using new data sources from an intensely monitored 5 6 km reach of an upland gravel bed river in northern england sediment impact sensors were placed in the bed to record the instantaneous passage of grains during transport events these sensors provide valuable information for the budget including 1 a downstream budget limit from which the rest of the budget can be calculated 2 estimates of sediment input from tributaries and 3 a better indication of active transport time used in the calculation of average transport rates further information collected from field studies include estimates of lateral inputs from the banks using field surveys and bank erosion pins and estimates of the variability of sediment porosity from bed grain size distributions budget calculations for different locations and time periods demonstrate large spatial and temporal variabilities in bedload transport rates over a short distance 3 km whilst some uncertainty in the new data sources remains this work highlights some limitations of the traditional budget approach and some potential solutions in particular the value of sediment impact sensors for sediment transport studies

fluvial suspended sediment transport from cold and warm based glaciers in svalbard an analysis of temporal variability in proglacial suspended sediment concentration is undertaken using time series data collected from three svalbard basins which include one largely cold based glacier austre broggerbreen one largely warm based glacier finsterwalderbreen and one intermediate polythermal glacier erdmannbreen the temporal variability in proglacial suspended sediment concentration is analysed using multiple regression techniques in which discharge is supplemented by other predictors acting as surrogates for variability in sediment supply at diurnal medium term and seasonal timescales these multiple regression models improve upon the statistical explanation of suspended sediment concentration produced by simple sediment rating curves but need to account for additional stochastic elements within the time series before they may be considered successful an interpretation of the physical processes which are responsible for the regression model characteristics is offered as a basis for comparing the different arctic glaciofluvial suspended sediment transport systems with that of their better known temperate glaciofluvial counterparts it is inferred that the largely warm based glacier is dominated by sediment supply from subglacial reservoirs which evolve in a similar manner to temperate glaciers and which cause a pronounced seasonal exhaustion of suspended sediment supply the largely cold based glacier however is dominated by sediment supply from marginal sources which generate a responsive system at short time scales but no significant seasonal pattern the intermediate polythermal glacier basin which was anticipated to be similar to the warm based glacier instead shows a highly significant seasonal increase in suspended sediment supply from an unusual subglacial reservoir emerging under pressure in the glacier foreland the temperate model of glaciofluvial suspended sediment transport is therefore found to be of limited use in an arctic context copyright 1999 john wiley sons ltd

thermal anomaly at the earth s surface associated with a lava tube abstract lava tubes are frequently encountered in volcanic areas the formation of lava tubes has strong implications on the volcanic hazard during effusive eruptions the thermal dissipation of lava flowing in a tube is reduced in respect to the lava flowing in an open channel so the lava may threaten areas that would not be reached by flows in open channels for this reason it is important to detect the presence of lava tubes in this work we propose a model to detect the presence and the characteristics of lava tubes by their thermal footprint at the surface we model numerically the temperature distribution and the heat flow both in the steady and the transient state and we take into account the principal thermal effects due to the presence of an active lava tube i e the conduction to the ground and the atmosphere the convection and the radiation in the atmosphere we assume that lava fluid is at high temperature in motion inside a sloping tube under the gravity force the thermal profile across the tube direction in particular the width of the temperature curve allows to evaluate the depth of the tube the values of maximum temperature and of tube depth allow to estimate the area of the tube section the shape of the temperature curve and its asymmetry can give information about the geometry of the tube if we observe volcanic areas at different times by thermal cameras we can detect anomalies and evaluate their causes during an eruption in particular we can evaluate whether they are due to active lava flows or not and what is their state for lava tubes we can connect thermal anomalies with lava tube position characteristics and state

continuous monitoring of bedload flux in a mountain gravel bed river an automatic bedload monitoring station has been established on the perennial tordera river a mediterranean mountain gravel bed stream located in ne spain bedload fluxes were obtained automatically at 1 min intervals using two birkbeck type pit bedload samplers aligned across the width of the channel flow depth and water surface slope were both measured continuously and synchronously with bedload data for five flow events show that bedload flux varies considerably bedload flux is high when it is compared with other perennial streams for a 15 min interval maximum channel average bedload flux was 0 83 kg m 1 s 1 bedload records also show that there is no direct relationship between bedload flux and grain shear stress the low correlation between bedload flux and hydraulics arises due to the different thresholds of initiation of motion for each flow event and the variable character of the bed between events for two individual floods there is a reasonable relationship between bedload flux and grain shear stress in part as a consequence of individual particle entrainment and patch movement over a stable coarse gravel bed during moderately high discharges these results demonstrate that the birkbeck system functions well in a mediterranean mountain gravel bed stream with a longitudinal slope of 2