topographical changes revealed by high resolution airborne lidar data the 1999 tsaoling landslide induced by the chi chi earthquake abstract the 1999 chi chi earthquake triggered the catastrophic tsaoling landslide in central taiwan we mapped the landslide area and estimated the landslide volume using a high resolution digital elevation model from airborne lidar light detection and ranging aerial photographs and topographic maps the comparison between scar and deposit volumes about 0 126 km3 and 0 150 km3 respectively suggests a coseismic volume increase of 19 due to decompaction during landsliding in july 2003 the scar and deposit volumes were about 0 125 km3 and 0 110 km3 respectively these estimates suggest that 4 years after the event the volume of landslide debris removed by river erosion was nearly 0 040 km3 these determinations are confirmed by direct comparison between the most accurate topographic models of the post landslide period indicating a very high erosion rate at the local scale 0 01 km3 year for the deposit area of the landslide such a large value highlights the importance of landslide processes for erosion and long term denudation in the taiwan mountain belt

complete dynamic modeling calibration for the thurwieser rock avalanche italian central alps abstract few rock avalanches have been witnessed and no exact real time description is available the 2 5 m m 3 punta thurwieser rock avalanche september 2004 italian central alps is a unique event for which many quantitative observations have been gathered this is the first case ever of a natural rock avalanche being recorded on video and for which an almost exact value of the total time duration from initial detachment to final deposition is available the landslide travelled over 2 9 km from its source partially in a glacial environment the initial failure and the time for the complete evacuation of the source area were studied and assessed by a series of photos the mean front velocities along the path have been estimated from the video the final geometry and the characteristics of the deposit have been obtained by gps measurements aerial photos field surveys and laboratory tests a quasi 3d continuum dynamic analysis of the landslide motion has been performed assuming both a voellmy and a frictional rheology in the model dan 3d for the first time the landslide front velocities have been used for back analyses and calibration of the rheological parameters together with the final shape and thickness of the deposit and its developing extension the dynamic flow resistance parameters initially calibrated with dan were adopted and validated in dan 3d showing good consistency they are consistent with the existing database for calibrated landslides of similar type and scale flow velocities on the path segment underlain by glacial deposits up to 55 65 m s 1 are more accurately predicted by adopting a frictional rheology up to 50 55 m s 1 with zero pore pressure and a 26 friction angle than by a voellmy rheology up to 40 45 m s 1 both observations and modelling show that glacial ice plays a substantial role in increasing the rock avalanche mobility

rock glaciers and mountain hydrology a review abstract in mountainous regions climate change threatens cryospheric water resources and understanding all components of the hydrological cycle is necessary for effective water resource management rock glaciers are climatically more resilient than glaciers and contain potentially hydrologically valuable ice volumes and yet have received less attention even though rock glacier hydrological importance may increase under future climate warming in synthesising data from a range of global studies we provide the first comprehensive evaluation of the hydrological role played by rock glaciers we evaluate hydrological significance over a range of temporal and spatial scales alongside the complex multiple hydrological processes with which rock glaciers can interact diurnally seasonally annually decadally and both at local and regional extents we report that although no global extent complete inventory for rock glaciers exists currently recent research efforts have greatly elaborated spatial coverage using these research papers we synthesise information on rock glacier spatial distribution morphometric characteristics surface and subsurface features ice storage and hydrological flow dynamics water chemistry and future resilience from which we provide the first comprehensive evaluation of their hydrological contribution we identify and discuss long intermediate and short term timescales for rock glacier storage allowing a more balanced assessment of the contrasting perspectives regarding the relative significance of rock glacier derived hydrological contributions compared to other water sources we show that further empirical observations are required to gain a deeper hydrological understanding of rock glaciers in terms of i their genesis and geomorphological dynamics ii total ice water volume iii water discharge and iv water quality lastly we hypothesise that at decadal and longer timescales under future climate warming degradation of ice within rock glaciers may represent an increasing hydrological contribution to downstream regions and thus increased hydrological significance while rock glacier water stores persist

discovery of a magma chamber and faults beneath a mid atlantic ridge hydrothermal field crust at slow spreading ridges is formed by a combination of magmatic and tectonic processes with magmatic accretion possibly involving short lived crustal magma chambers the reflections of seismic waves from crustal magma chambers have been observed beneath intermediate and fast spreading centres but it has been difficult to image such magma chambers beneath slow spreading centres owing to rough seafloor topography and associated seafloor scattering in the absence of any images of magma chambers or of subsurface near axis faults it has been difficult to characterize the interplay of magmatic and tectonic processes in crustal accretion and hydrothermal circulation at slow spreading ridges here we report the presence of a crustal magma chamber beneath the slow spreading lucky strike segment of the mid atlantic ridge the reflection from the top of the magma chamber centred beneath the lucky strike volcano and hydrothermal field is approximately 3 km beneath the sea floor 3 4 km wide and extends up to 7 km along axis we suggest that this magma chamber provides the heat for the active hydrothermal vent field above it we also observe axial valley bounding faults that seem to penetrate down to the magma chamber depth as well as a set of inward dipping faults cutting through the volcanic edifice suggesting continuous interactions between tectonic and magmatic processes

dynamics of the 1984 rock avalanche and associated distal debris flow on mount cayley british columbia canada implications for landslide hazard assessment on dissected volcanoes abstract in 1984 a mass of quaternary pyroclastic rock est vol 0 74 106m3 slid from the western flank of mount cayley volcano in southwest british columbia the disintegrating rock mass entrained a further 0 20 106 m3 and formed a rock avalanche that travelled a horizontal distance of 3 46 km from its source over a vertical elevation difference of 1 18 km equivalent to a fahrboschung of 19 from the superelevation of the debris trimline in the mid path it is estimated that velocities reached at least 42 m s in the upper part of its path velocities may have approached 70 m s the rock avalanche was partially transformed into a distal debris flow that travelled a further 2 6 km down turbid creek in a narrow channelised path to the squamish river temporarily blocking it the motion of the rock avalanche including the production of a distal debris flow was successfully simulated using a dynamic analytical model both the results of this analysis and field evidence indicate that the rock avalanche did not come to a halt in the upper part of its path as suggested by cruden and lu 1992 but travelled to its distal limit in one uninterrupted movement this finding has important implications for landslide hazard assessment at mount cayley and similar sites the landslide is typical of those which occur on the steep slopes of dissected volcanoes and is one of seven high velocity rock avalanches that have occurred in the garibaldi volcanic belt of southwest british columbia since 1855

dynamics and emplacement mechanisms of the successive baige landslides on the upper reaches of the jinsha river china abstract two successive baige landslides are presented in this study to investigate the dynamics and emplacement mechanisms field survey shows that the deposit characteristics of the first landslide are affected by the extremely fractured rock masses and the complex spatial distribution of lithologies in the source area this deposit consists of abundant angular megablocks on the surface supported by clasts with a relatively abundant content of rubble ranging from micrometre to decimetre sizes and rarely well preserved original stratigraphic sequence diapiric structure and convoluted structure these sedimentological characteristics imply that a simple differential shear process induced by compression is distributed through the entire avalanche masses with low internal disturbance during the emplacement of the first landslide the three dimensional discrete element simulations show that i the first landslide reaches its maximum average velocity of 41 m s in 28 s and eventually is bulldozed to a halt in the river within 80 s ii the second landslide is controlled by entrainment which impedes the avalanche from further accelerating and simultaneously imparts kinematic energy to the substrate eventually becoming entirely mobilized and reaching a maximum average velocity of 35 m s in 36 s in the dynamic process of the second landslide the significant entrainment induced enlarged volume its entrainment ratio reaches 3 3 is associated with the steep concave terrain water bearing substrate and lower roughness substrate basal boundary and overloading impact induced erosion is proposed to be the most significant contribution to this entrainment

quantitative assessment of weathering degree of the touzhai rock avalanche deposit in southwest china abstract weathering is one of the main preparatory causal factors for rock avalanche events and weathering assessment of involved materials can refine understanding of geomorphic processes of this class the weathering degree of the deposit of the touzhai basalt rock avalanche in china is quantitatively evaluated herein through an integrated geochemical analysis coupled with meso and micro scopic examination of fragments which can help to understand the inhomogeneity of weathering in rock slopes the clasts of 12 size classes of the debris making up the deposit ranging from meter sized boulder to fines of

on the accuracy of glacier outlines derived from remote sensing data deriving glacier outlines from satellite data has become increasingly popular in the past decade in particular when glacier outlines are used as a base for change assessment it is important to know how accurate they are calculating the accuracy correctly is challenging as appropriate reference data e g from higher resolution sensors are seldom available moreover after the required manual correction of the raw outlines e g for debris cover such a comparison would only reveal the accuracy of the analyst rather than of the algorithm applied here we compare outlines for clean and debris covered glaciers as derived from single and multiple digitizing by different or the same analysts on very high 1 m and medium resolution 30 m remote sensing data against each other and to glacier outlines derived from automated classification of landsat thematic mapper data results show a high variability in the interpretation of debris covered glacier parts largely independent of the spatial resolution area differences were up to 30 and an overall good agreement for clean ice with sufficient contrast to the surrounding terrain differences 5 the differences of the automatically derived outlines from a reference value are as small as the standard deviation of the manual digitizations from several analysts based on these results we conclude that automated mapping of clean ice is preferable to manual digitization and recommend using the latter method only for required corrections of incorrectly mapped glacier parts e g debris cover shadow

recent volcanic events and the distribution of hydrothermal venting at the lucky strike hydrothermal field mid atlantic ridge 1 we present new high resolution bathymetry and backscatter data acquired in 2006 with the rov victor 6000 over the lucky strike hydrothermal field mid atlantic ridge as long term monitoring of the lucky strike area momar project is being implemented these new high resolution data offer an unprecedented view of the distribution of hydrothermal edifices eruptive facies and small scale tectonic features in the lucky strike vent field we show that vents located in the nw and ne correspond with wide expanses of lumpy seafloor which we interpret as primarily made of broken chimneys and sulfide edifices they are found above scarps with relief 50 m or on associated mass wasting deposits by contrast the se and sw vents correspond with small expanses of lumpy seafloor and are located near smaller scarps which we interpret as more recent faults hydrothermal edifices in the sw venting area appear very recent postdating the emplacement and faulting of the most recent lava we propose that this difference in the age of hydrothermal edifices does not mean that hydrothermal venting itself is more recent in the southern part of the lucky strike field because preexisting sulfide deposits there may have been buried by recent volcanic deposits instead the older edifices in the northern part of the hydrothermal field may have been allowed more time to grow because they are set above the level of recent lava flows the formation of a lava lake is the most recent eruptive event detected at lucky strike lava drainback is evidenced by benches and lava pillars suggesting a close connection with an underlying magma reservoir which probably corresponds to the melt body imaged by singh et al 2006 we have found no evidence that this lake was active for months to decades as lava lakes at terrestrial volcanoes it may instead have formed as a lava pond with successive lava flows covering the eruptive vents as proposed for similar features at the epr the horizontal surface of the lake is deformed only near its southwestern shore along a nne trending set of faults and fissures which appear to control the distribution of hydrothermal chimneys

synergistic approach for mapping debris covered glaciers using optical thermal remote sensing data with inputs from geomorphometric parameters abstract debris cover on glacier boundaries critically impedes the global inventorying of glaciers and confounds most of the techniques developed for semi automated mapping of glaciers debris on the glacier referred as supraglacial debris and that occurring outside the glacier boundaries referred as periglacial debris being derived from a common source i e the valley rock tend to have a similar spectral response in the reflection region which renders them mutually indistinguishable however there exist temperature differences between them this aspect has been considered in this remote sensing based study to distinguish between the supraglacial and periglacial debris in a test area in the chenab basin himalayas by inclusion of thermal infrared tir bands in remote sensing data processing a synergistic multisensor approach for the delineation of debris covered glacier boundaries is used here which integrates the inputs from thermal terra aster sensor and optical irs p6 awifs sensor remote sensing data multispectral classification techniques and the dem derived geomorphometric parameters the results of this study corroborate earlier findings on utilization of temperature differences as one of the parameters in glacial studies the proposed synergistic approach therefore appears useful in accurate mapping of debris covered glaciers in the himalayan region

evidence of a recent magma dike intrusion at the slow spreading lucky strike segment mid atlantic ridge 1 mid ocean ridge volcanic activity is the fundamental process for creation of ocean crust yet the dynamics of magma emplacement along the slow spreading mid atlantic ridge mar are largely unknown we present acoustical seismological and biological evidence of a magmatic dike intrusion at the lucky strike segment the first detected from the deeper sections 1500 m of the mar the dike caused the largest teleseismic earthquake swarm recorded at lucky strike in 20 years of seismic monitoring and one of the largest ever recorded on the northern mar hydrophone records indicate that the rate of earthquake activity decays in a nontectonic manner and that the onset of the swarm was accompanied by 30 min of broadband 3 hz intrusion tremor suggesting a volcanic origin two submersible investigations of high temperature vents located at the summit of lucky strike seamount 3 months and 1 year after the swarm showed a significant increase in microbial activity and diffuse venting this magmatic episode may represent one form of volcanism along the mar where highly focused pockets of magma are intruded sporadically into the shallow ocean crust beneath long lived discrete volcanic structures recharging preexisting seafloor hydrothermal vents and ecosystems index terms 3035 marine geology and geophysics midocean ridge processes 7280 seismology volcano seismology 8419 8149 tectonophysics planetary tectonics 5475 4259 oceanography general ocean acoustics 9325 information related to geographic region atlantic ocean keywords mid atlantic ridge earthquake hydroacoustic

compilation of a glacier inventory for the western himalayas from satellite data methods challenges and results abstract due to their sensitive reaction to changes in climatic conditions glaciers have been selected as an essential climate variable ecv although a large amount of ice is located in the himalayas this region is yet only sparsely represented in global glacier databases accordingly a sound and comprehensive change assessment or determination of water resources was not yet possible in this study we present a new glacier inventory for the western himalayas compiled from landsat etm scenes acquired between 2000 and 2002 coherence images from alos palsar image pairs the srtm digital elevation model dem and the aster global dem gdem several specific challenges for glacier mapping were found in this region and addressed they are related to debris cover orographic clouds locally variable snow conditions and creeping permafrost features in cold dry regions additional to seven topographic parameters that are obtained from the aster gdem for each glacier we also determined the relative amount of debris cover on the glacier surface the inventory contains 11 400 glaciers larger than 0 02 km2 which cover a total area of 9 310 km2 analysis of the inventory data revealed characteristic patterns of mean glacier elevation and relative debris cover amounts that might be related to the governing climatic conditions the full dataset will be freely available in the glims glacier database to foster further analyses and modeling of the glaciers in this region

geochemical discrimination of metabasalt rocks of the fan karategin transitional blueschist greenschist belt south tianshan tajikistan seamount volcanism and accretionary tectonics the fan karategin metamorphic belt south tianshan tajikistan is regarded to be an ancient subduction accretionary complex and is composed of three tectonostratigraphic units which display lithologies consistent with different tectonic settings the mafic schists which make up the major part of the older unit of the belt contain both alkali and tholeiitic metabasalts on the basis of rare earth and other immobile element characteristics the alkali metabasalts are akin to within plate ocean island basalts whereas the tholeiitic metabasalts resemble e type morb the association is interpreted to have been formed on seamount like structures under a within plate plume bedded cherts and marbles in the unit are regarded as ancient pelagic sediments and carbonate caps developed upon basaltic seamounts respectively dismemberment of the seamount related basalts and pelagic sediments and the high p low t prograde metamorphism of the unit rocks up to transitional blueschist greenschist facies was the result of paleoseamount submergence into a subduction zone this unit is tectonically overlain by arc derived metavolcanic unit and a disrupted mainly clastic unit of upper ordovician lower silurian age metavolcanic and metasedimentary rocks of the two upper units have geochemical characteristics compatible with subduction related origin the lithological assemblages of the individual units and their juxtaposition suggest an origin involving collision accretionary processes the fan karategin belt is a subduction accretionary complex which formed during subduction of oceanic crust under a volcanic arc and was subjected to tectonic juxtaposition and imbrication of seamount deep sea trench and volcanic arc sequences

climate change and glacier area shrinkage in the qilian mountains china from 1956 to 2010 glaciers in the qilian mountains located in the northeastern part of the tibetan plateau constitute an important freshwater resource for downstream populations and natural systems to enhance our understanding of the variability of the glaciers temporally and spatially comprehensive information on them is needed in this study the glacier outlines of similar to 1990 similar to 2000 and similar to 2010 for the whole area were delineated in a semi automated manner using band tm3 tm5 ratio images of landsat etm or tm scenes with the help of a merged aster gdem srtm v4 1 digital elevation model combining our own results with those of previously published studies that span the period back to 1956 we found that the glacier area shrank by 30 8 from 1956 to 2010 and the shrinkage accelerated remarkably in the past two decades the linear trends of annual air temperature and precipitation measured at weather stations within the glacierized areas were 0 03 0 05 c a 1 significant only after 2000 and 0 37 1 58 mm a 1 not significant respectively from 1961 to 2010 glaciers shrank mainly due to the increasing temperature glaciers in the qilian mountains are very unlikely to have experienced positive mass balance over the past decade moreover given the trend toward higher temperatures the glaciers in this region will continue to shrink

characteristics and transport mechanism of the nyixoi chongco rock avalanche on the tibetan plateau china abstract for studying rock avalanches complex surficial and internal characteristics have been regarded as important indicators for understanding avalanche transport mechanism in the present study deposits of a massive holocene rock avalanche termed the nyixoi chongco rock avalanche located on the lhasa terrane of tibetan plateau in china are investigated based on a combination of remote sensing data and in situ observations it is revealed that abundant surface landforms including toreva blocks longitudinal and transverse ridges en echelon ridges and hummocks are commonly developed corresponding to these surface morphologies a series of internal sedimentary structures including jigsaw structures inner shear zones aligned clasts diapiric structures convoluted laminations and basal decollements are also well developed through an analysis of these surficial and internal characteristics we propose that a rapid motion similar to a laminar flow most likely occurred after the avalanche mass detaching from the source area in this process the detached avalanche mass was mainly emplaced by a frictional simple shear process characterized by a bulldozing effect that occurred between the sliding mass and the substrate from the proximal to the distal sections of the avalanche the transport of the rock mass can be classified into four major processes an extension dominated sliding process in the transition zone a compression dominated sliding process in subzones iii 1 and iii 2 of the accumulation zone iii a sliding process co dominated by compression and lateral spreading in subzone iii 3 and a rapid radial spreading process in subzone iii 4 the results of our study provided an improved understanding of the transport mechanisms of this rock avalanche

glacier changes in the koshi river basin central himalaya from 1976 to 2009 derived from remote sensing imagery we use remote sensing and gis technologies to monitor glacier changes in the koshi river basin central himalaya the results indicate that in 2009 there were 2061 glaciers in this region with a total area of 3225 90 3 km 2 this glacier population is divided into 1290 glaciers with a total area of 1961 54 9 km 2 on the north side of the himalaya nsh and 771 glaciers with a total area of 1264 35 4 km 2 on the south side of the himalaya ssh from 1976 to 2009 glacier area in the basin decreased by about 19 5 6 0 59 0 17 a 1 glacier reduction was slightly faster on ssh 20 3 5 6 than on nsh 18 8 5 6 the maximum contribution to glacier area loss came from glaciers within the 1 5 km 2 area interval which accounted for 32 of total area loss between 1976 and 2009 the number of glaciers in the koshi river catchment decreased by 145 between 1976 and 2009 glacier area on ssh decreased at a rate of 6 2 3 2 0 68 0 36 a 1 faster than on nsh where the rate was 2 5 3 2 0 27 0 36 a 1 during 2000 09 based on records from tingri weather station we infer that temperature increase and precipitation decrease were the main causes of glacier thinning and retreat during the 1976 2000 period glacier retreat during the 2000 09 period appears to be controlled by temperature increase since precipitation increase over this period did not offset ice losses to surface melting

large landslides associated with a diapiric fold in canelles reservoir spanish pyrenees detailed geological geomorphological mapping trenching and electrical resistivity imaging abstract detailed geomorphological geological mapping in canelles reservoir the spanish pyrenees reveals the presence of several large landslides overlooked in previous cartographic works one of the slope movements designated as the canelles landslide corresponds to a 40 10 6 m 3 translational landslide reactivated in 2006 by a severe decline in the reservoir water level the geomorphic features mapped in the upper part of the canelles landslide including surface ruptures corroborated by electrical resistivity imaging and trenching indicate multiple displacement episodes previous to the 2006 human induced event consistently the stratigraphic and structural relationships observed in a trench record at least two displacement events older and larger in magnitude than the 2006 reactivation the oldest recorded event occurred in the 6th to 7th centuries and the second in 1262 1679 yr ad this latter episode might be correlative to the 1373 ribagorza earthquake m w 6 2 which caused the reactivation of a landslide and the consequent destruction of a village in the adjacent valley the available data indicate that over more than one millennium the kinematics of the landslide has been characterised by discrete small displacement episodes these data together with the available literature on rapid rockslides do not concur with the acceleration predicted by modelling in a previous investigation which foresees a speed of 16 m s 1 despite the low average dip of the sliding surface 9 10 this case study illustrates that the trenching technique may provide valuable practical information on the past behaviour of landslides covering a much broader time span than instrumental and historical records

diagnostic characteristics and paleodynamics of supraglacial rock avalanches innerdalen western norway abstract misinterpretation of rock avalanche deposits in mountain environments is not uncommon because of the complex interactions between rock avalanches and glaciers this paper for the first time presents a detailed description of suspicious rock boulder deposits which are remnants of a rock avalanche onto a late pleistocene glacier the boulder deposits cover around 1 1 km 2 and are distributed over an area of around 7 5 km 2 and a variety of landforms three closely nested distinct terminal moraines 0 45 km 2 and dislocated terminal moraines 0 34 km 2 entirely built up of large boulders lateral moraines that decrease in elevation over a short distance and connect to the terminal moraines small patches 0 02 km 2 of boulders that occur in islands on a peat dominated valley floor and large patches of boulder fields 0 25 km 2 in size hanging 350 m above the valley floor the latter are disconnected from any potential source area 10 be cosmogenic nuclide ages of the three terminal moraines give an indistinguishable late pleistocene age of 13 6 1 4 ka whereas the largest boulder field that is located on the opposite side of the valley from the failed mountain yields a 10 be age of 14 1 0 4 ka which is slightly older but indistinguishable from the moraine deposits within uncertainty margins all boulder deposits add up to a volume of 31 10 6 m 3 the interpretation of a single rock avalanche source for those landforms is further confirmed by numerical runout modeling using dan3d a failure of the entire volume from skarfjellet mountain would result in a runout pattern that is identical to that of the distributed boulder fields when considering that the valley was filled with a glacier around 350 m thick the rock avalanche would not reach the position of the terminal moraines however a glacial re advance could have transported the boulders to that position the late pleistocene rock avalanche was followed by a holocene rock avalanche with a volume of 23 10 6 m 3 and a typical lobate deposit damming the innerdalen valley and creating a lake 10 be ages indicate that this event occurred 7 97 0 94 ka ago structural measurements performed on high resolution lidar scans show a strongly jointed source rock with three joint sets with dip dip direction 81 034 86 331 and 77 354 and a foliation with 22 003 the kinematic of the failures can thus be a combination of small scale wedge failures and planar sliding on shallow dipping foliation our detailed description can enable a better identification and interpretation of similar deposits in other mountain areas

assessing the status of glaciers in part of the chandra basin himachal himalaya a multiparametric approach this study investigates the change in multiple glacier parameters of three valley type glaciers sakchum sc chhota shigri cs and bara shigri bs located in chandra basin himachal himalaya sharing the same climatic regime and assesses the control of nonclimatic factors on wholesome glacier response multitemporal satellite remote sensing data from landsat tm etm oli 1993 2014 and terra aster 2002 2014 along with an srtm digital elevation model were used for extraction of the glacier parameters results show that while sc and bs retreated sc 10 65 2 52 m y bs 15 51 2 52 m y and lost area sc 0 49 0 0032 km2 bs 1 18 0 0032 km2 the cs remained relatively stable retreat rate 4 06 2 52 m y area loss 0 19 0 0032 km2 during 1993 2014 however results of surface ice velocities siv change sc 24 41 cs 21 60 and bs 28 49 and surface elevation change sc 1 22 m y cs 0 91 m y and bs 1 21 m y suggest a comparable slowing down and surface lowering from 2002 to 2014 debris cover also varied substantially sc 30 25 cs 11 96 bs 19 61 on these glaciers results reveal that higher retreat deglaciation of glaciers was associated with higher altitudinal range slow siv in lower ablation zones laz and glacier hypsometry debris cover on glaciers was found to be controlled by slope higher deglaciation rates higher siv in the upper ablation zone uaz coupled with lower siv in laz and surface lowering glacier siv was primarily governed by slope gradient differential surface lowering and size of accumulation zone acz the siv results confirm the presence of stagnant zones in the lower ablations of sc 1 km upstream and bs 6 km upstream and a major siv dropdown in the uaz sc 34 48 bs 37 35 indicating the expansion of stagnant zones farther up glacier surface lowering seemed to be influenced by ice flux changing spatial distribution of debris cover presence of supraglacial lakes and ice cliffs bordering them melting around supraglacial lakes and backwasting of ice cliffs may be the prime reasons behind intense mass loss observed in the stagnant zone of the bara shigri glacier where surface lowering was 32 higher than glacier wide thinning differential surface lowering in glaciers reduced the surface gradient and hence the siv also rapid surface gradient changes and siv dropdown in the sakchum glacier indicate possible development of supraglacial lakes on it in the future interestingly despite close proximity sc cs and bs demonstrate three distinct ablation patterns reemphasizing the role of nonclimatic factors overall the study states that mutual variation of glacier parameters together with nonclimatic factors exercise a great control on glacier response

impact of communal irrigation on the 2018 palu earthquake triggered landslides anthropogenic changes to the environment can enhance earthquake triggered landslides yet their role in earthquake disasters is often overlooked co seismic landslides frequently involve liquefaction of granular materials a process that reduces shear strength and facilitates downslope motion even on gentle slopes irrigation systems can increase liquefaction susceptibility and compromise otherwise stable slopes here we investigate devastating landslides that affected palu indonesia during the 28 september 2018 earthquake of moment magnitude 7 5 we document fields and buildings translated over 1 km down slopes of 2 and show that landslides were limited to irrigated ground a liquefied detachment was rooted upslope in a conveyance canal that supplied water to the irrigation network a strong correlation between landslide displacement irrigation infrastructure and the highest slopes 1 5 suggests a causative mechanism that should provoke urgent assessment of gently sloping irrigated terrain elsewhere in sulawesi and in tectonically active areas worldwide landslides triggered during the palu 2018 earthquake correlate spatially with the presence of irrigation systems according to satellite analyses suggesting that liquefaction of alluvial fans played a role

recognition of supraglacial debris in the tianshan mountains on polarimetric sar images abstract debris cover is widely present in the ablation areas of mountain glaciers such debris plays an important role in glacier mass balance but it complicates the glacier boundary and area estimation when using remotely sensed images automatic recognition of the debris is much more difficult than recognizing bare ice on optical remotely sensed images because the debris has almost the same spectral characteristics of the surrounding terrain in this paper the scattering characteristics of the debris on the c and l band polarimetric sar images are presented and analyzed to study the possibility of recognizing debris thickness and extent the koxkar glacier in the central tianshan mountain range was selected as the study area it was found that debris is distinct from bare ice in cross polarization hv of both the l and c bands the l band volume scattering component acquired from target decomposition increases with debris thickness when the debris is less than 25 cm deep but the volume scattering does not increases if the debris is thicker than 25 cm in contrast the c band sar data does not appear to be sensitive to debris thickness this difference may be caused by different radar penetration depth of the debris on the basis of the polarimetric property analysis two methods were developed to determine the extent of the debris in the first method the simple threshold to distinguish debris from non debris areas is presented using this threshold approximately 90 of the debris can be recognized in the second method by combining more polarimetric features and support vector machines recognition of debris reaches an accuracy greater than 95

seismic domains within the gissar kokshal seismic zone soviet central asia by evaluating seismological data from the belt of shallow intraplate seismicity known as the gissar kokshal seismic zone in soviet central asia in conjunction with recent data on the shallow crustal structure and longer term geologic deformation we show that certain size classes of earthquakes are characteristic of adjacent and in some places overlapping geologic tectonic settings we call these settings seismic domains they are both geologically and seismologically distinct i e they contain different rocks and structures and have different frequency magnitude relationships for example in terms of number of events gissar kokshal seismicity is dominated by the microearthquakes that have occurred within the sedimentary rocks of the vakhsh fold thrust belt these are all shallow and have occurred mostly within the frontal portions of the thrust sheets more rarely moderate size m 5 5 earthquakes have ruptured the thrust ramps on the other hand the major strain release in this region has accompanied the large 5 5 m 8 1 shallow earthquakes on basement faults in the southern gissar range adjacent to the fold thrust belt within these ranges there is relatively little microearthquake activity that dichotomy indicates that a significantly different seismic hazard is associated with each of these areas but the seismological distinction is obscured along the front of the fold thrust belt where the domain of small shocks in the sedimentary rocks overlaps the domain of large earthquakes on basement faults to explain the localization of the large basement events along the southern flank of the fold thrust belt adjacent to the fold thrust belt we hypothesize a mechanism of thrust sheet loading thrust loads are greatest in this region since thrust sheets have overridden large basement block uplifts beneath the illiac and peter the first range faults

globally aligned photomosaic of the lucky strike hydrothermal vent field mid atlantic ridge 37 18 5 n release of georeferenced data mosaic construction and viewing software 1 we present a georeferenced photomosaic of the lucky strike hydrothermal vent field mid atlantic ridge 37 18 n the photomosaic was generated from digital photographs acquired using the argo ii seafloor imaging system during the 1996 lustre cruise which surveyed a 1 km2 zone and provided a coverage of 20 of the seafloor the photomosaic has a pixel resolution of 15 mm and encloses the areas with known active hydrothermal venting the final mosaic is generated after an optimization that includes the automatic detection of the same benthic features across different images feature matching followed by a global alignment of images based on the vehicle navigation we also provide software to construct mosaics from large sets of images for which georeferencing information exists location attitude and altitude per image to visualize them and to extract data georeferencing information can be provided by the raw navigation data collected during the survey or result from the optimization obtained from image matching mosaics based solely on navigation can be readily generated by any user but the optimization and global alignment of the mosaic requires a case by case approach for which no universally software is available the lucky strike photomosaics optimized and navigated only are publicly available through the marine geoscience data system mgds http www marine geo org the mosaic generating and viewing software is available through the computer vision and robotics group web page at the university of girona http eia udg es rafa mosaicviewer html

glacier change in the gangdise mountains southern tibet since the little ice age abstract delineating glacier change during the little ice age lia is of great importance when attempting to understand regional climatic changes and can also help to improve the understanding of any predictions of future glacial changes however such knowledge is still lacking for some critical regions of the tibetan plateau tp in this study we mapped 4188 contemporary glaciers and reconstructed 1216 lia areas of glacial coverage in the gangdise mountains to the north of the himalaya using google earth satellite imagery we estimated their paleoglacial areas and equilibrium line altitudes elas based on the toe to headwall altitude ratio thar method results show that most glaciers are small

remote sensing science and technology for studying glacier processes in high asia a large number of multispectral and stereo image data are expected to become available as part of the global land ice measurements from space project we investigate digital elevation model extraction anisotropic reflectance correction and selected glacier analysis tasks that must be developed to achieve full utility of these new data results indicate that glaciers in the karakoram and nanga parbat himalaya northern pakistan exhibit unique spectral spatial and geomorphometric patterns that can be exploited by various models and algorithms to produce accurate information regarding glacier extent supraglacial features and glacier geomorphology the integration of spectral spatial and geomorphometric features coupled with approaches for advanced pattern recognition can help geoscientists study glacier mass balance glacier erosion sediment transfer efficiency and landscape evolution

multispectral imaging contributions to global land ice measurements from space global land ice measurements from space glims is an international consortium established to acquire satellite images of the world s glaciers analyse them for glacier extent and changes and assess change data for causes and implications for people and the environment although glims is making use of multiple remote sensing systems aster advanced spaceborne thermal emission and reflection radiometer is optimized for many needed observations including mapping of glacier boundaries and material facies and tracking of surface dynamics such as flow vector fields and supraglacial lake development software development by glims is geared toward mapping clean ice and debris covered glaciers terrain classification emphasizing snow ice water and admixtures of ice with rock debris multitemporal change analysis visualization of images and derived data and interpretation and archiving of derived data a global glacier database has been designed at the national snow and ice data center nsidc boulder colorado parameters are compatible with and expanded from those of the world glacier inventory wgi these technology efforts are summarized here but will be presented in detail elsewhere our presentation here pertains to one broad question how can aster and other satellite multispectral data be used to map monitor and characterize the state and dynamics of glaciers and to understand their responses to 20th and 21st century climate change our sampled results are not yet glaciologically or climatically representative our early results while indicating complexity are generally consistent with the glaciology community s conclusion that climate change is spurring glacier responses around the world mainly retreat whether individual glaciers are advancing or retreating the aggregate average of glacier change must be climatic in origin as nonclimatic variations average out we have discerned regional spatial patterns in glaciological response behavior these patterns are best attributed to climate change variability and to regional differences in glacier size and response times in many cases glacier length changes under represent the magnitude of glacier ablation because thinning sometimes without immediate length changes is also important an expanded systematic uniform analysis of many more glaciers is needed to isolate the glacier response components due to climatic and nonclimatic perturbations to produce quantitative measures of regional variation in glacier changes and to predict future regional glacier trends relevant to water resources glaciological hazards and global sea level this comprehensive assessment to be completed in stages is expected to lend a critically needed filter to identify successful climate models that explain recent glacier changes and change patterns and hence are apt to describe future changes and to eliminate unsuccessful models

getting the bigger picture using precision remotely operated vehicle rov videography to acquire high definition mosaic images of newly discovered hydrothermal vents in the southern ocean direct visual observations from submersible vehicles at hydrothermal vents typically only reveal a fraction of the vent environment at any one time we describe the use of precision remotely operated vehicle rov videography to produce extensive mosaic images of hydrothermal vent chimneys and surrounding seafloor areas c 250 m2 with sufficient resolution to determine distributions of macro and megafauna doppler velocity log navigation dvlnav was used to follow overlapping vertical survey lines in a fixed plane facing a vent chimney while acquiring high definition video imagery using a forward looking camera the dvlnav also enabled the vehicle to follow overlapping horizontal survey lines while acquiring seafloor imagery from a downward looking video camera and mapping variations in seawater temperature digital stills images extracted from video were used to compile high resolution composite views of the surveyed areas applying these image acquisition techniques at vent fields on the east scotia ridge southern ocean revealed consistent patterns of faunal zonation around vent sources variations in proportions of faunal assemblage types on different faces of a vent chimney and differences in proportions of faunal assemblages between two different vent fields the technique can therefore be used to determine the composition and spatial distribution of fauna across complex areas of topography such as vent fields where mosaic images of vertical structures cannot currently be acquired using other platforms such as autonomous underwater vehicles auvs these image acquisition techniques demonstrated here in the first rov dives at newly discovered vent fields may offer an appropriate technology for rapid baseline studies required by the potential mining of seafloor massive sulfides sms

seismic layer 2a variations in the lucky strike segment at the mid atlantic ridge from reflection measurements 1 the sismomar experiment carried out seismic measurements of the slow spreading lucky strike segment of the mid atlantic ridge located approximately 300 km south of the azores platform we present results from a segment scale reflection study of seismic layer 2a that is centered on the lucky strike volcano and covers the central 54 km of the 70 km long segment and extends 30 km on both sides of the ridge axis our study allows new conclusions about the role of tectonic magmatic and hydrothermal processes in shaping the upper crustal structure of the lucky strike segment the seismic reflection measurements show an almost constant layer 2a two way time within the median valley and an abrupt layer 2a two way time decrease off axis this two way time decrease is caused by a layer 2a velocity increase on the order of 1 km s the uniform two way time in the median valley results from a constant thickness layer 2a which could be caused by the existence of a porosity threshold linked to the lithologic lava dike boundary the regularity of the layer 2a 2b interface within the median valley indicates that layer 2a is built entirely inside the median valley the off axis velocity increase is consistent with hydrothermal alteration and the aging of the crust

recent glacier retreat in the caucasus mountains russia and associated increase in supraglacial debris cover and supra proglacial lake development this paper reports changes in supraglacial debris cover and supra proglacial lake development associated with recent glacier retreat 1985 2000 in the central caucasus mountains russia satellite imagery landsat tm and etm was used to map the surface area and supraglacial debris cover on six neighbouring glaciers in the adylsu valley through a process of manual digitizing on a false colour composite of bands 5 4 3 red green blue the distribution and surface area of supraglacial and proglacial lakes was digitized for a larger area which extended to the whole landsat scene we also compare our satellite interpretations to field observations in the adylsu valley supraglacial debris cover ranges from 25 on individual glaciers but glacier retreat between 1985 and 2000 resulted in a 3 6 increase in the proportion of each glacier covered by debris the only exception to this trend was a very small glacier where debris cover did not change significantly and remote mapping proved more difficult the increase in debris cover is characterized by a progressive up glacier migration which we suggest is being driven by focused ablation and therefore glacier thinning at the up glacier limit of the debris cover resulting in the progressive exposure of englacial debris glacier retreat has also been accompanied by an increase in the number of proglacial and supraglacial lakes in our study area from 16 in 1985 to 24 in 2000 representing a 57 increase in their cumulative surface area these lakes appear to be impounded by relatively recently lateral and terminal moraines and by debris deposits on the surface of the glacier the changes in glacier surface characteristics reported here are likely to exert a profound influence on glacier mass balance and their future response to climate change they may also increase the likelihood of glacier related hazards lake outbursts debris slides and future monitoring is recommended

lucky strike seamount implications for the emplacement and rifting of segment centered volcanoes at slow spreading mid ocean ridges the history of emplacement tectonic evolution and dismemberment of a central volcano within the rift valley of the slow spreading mid atlantic ridge at the lucky strike segment is deduced using near bottom sidescan sonar imagery and visual observations volcano emplacement is rapid 1 myr associated with focused eruptions and with effusion rates feeding lava flows that bury tectonic features developed prior to and during volcano construction this volcanic phase likely requires efficient melt pooling and a long lived crustal magma chamber as a melt source a reduction in melt supply triggers formation of an axial graben rifting the central volcano and the onset of seafloor spreading may eventually split it at lucky strike this results in two modes of crustal construction eruptions and tectonic activity focus at a narrow graben that bisects the central volcano and contains the youngest lava flows accumulating a thick layer of extrusives away from the volcano summit deformation and volcanic emplacement is distributed throughout the rift valley floor lacking a clear locus of accretion and deformation volcanic emplacement on the rift floor is characterized by axial volcanic ridges fed by dikes that propagate from the central axial magma chamber the mode of rapid volcano construction and subsequent rifting observed at the lucky strike seamount is common at other central volcanoes along the global mid ocean ridge system

machine learning classification of debris covered glaciers using a combination of sentinel 1 2 sar optical landsat 8 thermal and digital elevation data abstract debris cover on glacier surfaces hampers the accurate detection of debris covered ice using traditional techniques based on image band ratios therefore this study tests a new automatic classification scheme for hierarchical mapping of glacier surfaces based on machine learning classifiers including k nearest neighbors knn support vector machine svm gradient boosting gb decision tree dt random forest rf and multi layer perceptron mlp several raster layer combinations synthetic aperture radar sar coherence image derived from sentinel 1 data visible near infrared to short wave infrared bands from sentinel 2 thermal information from landsat 8 and geomorphometric parameters from the advanced land observing satellite alos world 3d 30 m mesh aw3d30 digital elevation model were tested to delineate the debris covered glaciers in the gilgit baltistan pakistan and shaksgam valley china the highest over classification accuracy 97 was obtained using the rf classifier followed by the gb and svm with radial basis function kernel and utilizing all of the multisensor sentinel landsat alos data notably the rf classifier showed to be robust to parameter settings fast and accurate for mapping debris covered ice gb classifier showed similar performance as rf despite it has a moderately lower accuracy compared to rf although svm classifier has a slower in the speed of tuning hyper parameter it still performs the third best classification accuracy as the multisensory data we used is freely and near globally available our methodology potentially could be applied for precise delineation of debris covered glaciers in other areas

erosional processes as a control on the structural evolution of an actively deforming fold and thrust belt an example from the pamir tien shan region central asia the foreland of the pamir mountains displays an unusual orogenic topography in which an active north vergent thin skinned fold and thrust belt shows no topographic foredeep in advance of the thrust sheets instead the thrusts are impinging on a topographic barrier formed by the southern edge of the tien shan the deformation front of this thrust belt is coincident with a deeply incised river valley occupied by a large river the surkhob we suggest that this river played a key role in the evolution of this orogenic system by acting as a lateral conveyor belt for the transport of mass delivered to the deformation front by thrusting on the basis of reconnaissance geologic mapping it is clear that the present system developed in the late miocene or pliocene when the tien shan were uplifted within an existing foreland basin as the tien shan highland developed a longitudinal river within the foreland basin was trapped between the north directed thrusts and the tien shan highland with continued deformation the river was squeezed into a narrow canyon and since that time the system has been in an unusual equilibrium where thrusting acts to push the deformation front northward toward the tien shan but fluvial erosion and transport act to keep it in a constant position geologic relationships indicate that the vakhsh thrust the frontal thrust of the north directed system is now emerging on an erosion surface beneath a thin quaternary cover throughout the canyon suggesting that the river has been unable to keep pace with the tectonic mass flux and the thrust front as well as the river have been pushed northward across the beveled edge of what was originally the southern edge of the tien shan we suggest that the original deformation front of the tien shan now lies 10 km south of the present day topographic front of the tien shan beneath the north vergent vakhsh thrust as indicated by 1 a near vertical zone of intense basement seismicity the petrovsky seismic zone 2 an en echelon array of backthrusts along the south flank of the peter the first range and 3 footwall cutoff relationships of the vakhsh thrust system order of magnitude mass balance considerations based on sediment budgets support this conclusion but suggest that the mass imbalance may be small thus large volumes of material may have passed through the thrust fron and been carried out of the system by erosion a relationship that may account for the narrow 30 50 km wide band of deformed sedimentary rock between the pamir salient and the tien shan the present near equilibrium is maintained by long term tectonic transport rates and fluvial transport rates the latter closely linked to climate particularly precipitation thus although there is apparently a mass pile up within this system other systems of this type might show grossly different structural and stratigraphic relationships depending on the amount of rainfall and corresponding variations in rates of fluvial sediment transport similar settings can be recognized in the active thick skinned thrust systems of the tien shan and ancient systems like the laramide belt of western north america

structural and seismic evidence for intracontinental subduction in the peter the first range central asia this paper examines the stratigraphy structure and seismicity of the peter the first range an actively deforming foreland basin in soviet tadjikistan the range represents a highly deformed segment of a large intracontinental basin the tadjik depression which is being shortened in response to the cenozoic convergence between two orogenic massifs the pamir and the tien shan ranges the late jurassic to paleogene stratigraphy of the peter the first range includes more than 2 000 m of shallow marine to nonmarine sediments deposited under relatively quiescent conditions close to sea level in contrast the correlative units of the northernmost pamir directly south of the peter the first range show evidence of proximity to a major uplifted source area to the south these mesozoic early cenozoic strata are overlain by thick sequences of alluvial sandstone and conglomeratic units that coarsen upward through the neogene and record the progressive uplift of the pamir shortening within the peter the first range is recorded by kilometer scale isoclinal upright to over turned folds and imbricate north verging thrusts that emerge near the northern edge of the range and mark the active tectonic boundary with the tien shan most of the deformation appears to postdate the accumulation of the mio pliocene molasse the stratigraphy and structure of the region are best explained by a model of the mesozoic tadjik depression as an intracontinental foreland basin developed in a back arc position with respect to the active andean or collisional orogens located in northern afghanistan and the pamir seismicity in the region is dominated by earthquakes extending from the surface to 12 km depth apparently occurring within the deformed sediments of the peter the first range a subhorizontal zone of relatively low activity at this depth may mark the location of a basal detachment that underlies a structurally thickened sedimentary section this aseismic zone is in turn underlain by a south dipping belt of seismicity that extends from about 17 to 35 km depth and which can be traced updip to the seismogenic crystalline basement of the tien shan range to the north we interpret this south dipping structure as a zone of intracontinental subduction that may be an updip continuation of the enigmatic intermediate depth wadati benioff zone beneath the pamir range to the south

entrainment of debris in rock avalanches an analysis of a long run out mechanism many rock avalanches entrain and liquefy saturated soil from their paths evidence for this includes mud displaced from the margins of rock avalanche deposits substrate material smeared along the base of deposits extrusion of liquefied soil upward through the deposits and increases of volume a hypothesis first suggested in 1881 and since reinforced by several authors suggests that entrainment of substrate material increases mobility although the process has been discussed in the literature for more than 100 years few detailed and quantitative descriptions exist the main purpose of this paper is to describe two recent cases from british columbia canada where rockslides entrained substrate on a very large scale influencing the character of the events estimated volume balance curves based on detailed field mapping are provided for both cases dynamic analyses are carried out using a numerical model and using the same set of rheological parameters the mechanism of material entrainment and displacement is discussed the data suggest that rapid rock failures entraining very large quantities of saturated substrate material represent a special type of landslide transitional between rock avalanche and debris avalanche many rock avalanches can thus be seen as end members of a continuum of phenomena involving rock failure followed by interaction with saturated substrate

prokaryote communities at active chimney and in situ colonization devices after a magmatic degassing event 37 n mar emso azores deep sea observatory the mixing zone between high temperature hydrothermal fluids and seawater produces redox gradients promoting the development of unique ecosystems based on chemotrophy the structure of microbial communities depends on their environment which can vary according to space and time hydrothermal circulation within the oceanic crust determines the chemical composition and flow of fluids depending on underground events earthquakes volcanic episodes and impacts the development of microbial communities this link between hydrothermal vent communities and deep geological events is the focus of the present study the first of its kind for slow spreading ridge in this study we present a unique set of multidisciplinary data collected from 2008 to 2011 on the eiffel tower hydrothermal site lucky strike vent field mid atlantic ridge we benefit from continuous geophysical monitoring temperature seismicity of the site annual sampling of hydrothermal fluids hot and diffuse for geochemistry analyses sampling of hydrothermal chimneys and an in situ microbial colonization experiments over a year for microbial study the high co2 content and concentrations of major elements cl ca si and so4 in the end member fluids collected in 2010 indicate that a magmatic degassing occurred between 2009 and 2010 under the lucky strike hydrothermal field this is supported by the large temperature variations observed in march april 2010 these magmatic co2 inputs seem to have affected microbial communities colonizing the high temperature chimney as well as the basalts in the more diffuse and mixed zone promoting the development of thermophilic anaerobic archaea and bacteria archaeoglobales nautiliales nitratiruptoraceae

automated classification of debris covered glaciers combining optical sar and topographic data in an object based environment abstract satellite imagery is increasingly used to monitor glacier area changes and create glacier inventories robust and efficient pixel based band ratios have proven to be accurate for automatically delineating clean glacier ice however such classifications are restricted on debris covered ice due to its spectral similarity with surrounding terrain object based image analysis obia has emerged as a new analysis technique within remote sensing it offers many advantages over pixel based classification techniques due to the ability to work with multiple data sources and handle data contextually and hierarchically by making use of obia capabilities we automatically classify clean ice and debris covered ice in the challenging area surrounding mount manaslu in nepal using optical landsat 8 topographic void filled srtm and sar coherence alos palsar data clean ice was classified with a mean accuracy of 93 whilst debris covered ice was classified with an accuracy of 83 when compared to manually corrected outlines providing a total glacier accuracy of 91 with further developments in the classification steep tributary sections of ice could be contextually included raising the accuracy to over 94 one prominent advantage of obia is that it allows some post processing and correction of the glacier outlines automatically reducing the amount of manual correction needed obia incorporating sar coherence data is recommended for future mapping of debris covered ice

glacial cover mapping 1987 1996 of the cordillera blanca peru using satellite imagery multitemporal glacier area mapping is a key element in accurately determining fresh water reserves as well as providing an indicator of climate change in peru the first glacier inventory was based on visual interpretation of aerial photos requiring several years of effort landsat thematic mapper satellite imagery on the other hand provides an increasingly employed alternative for the monitoring of changes in glacier area and in other glaciological parameters by means of normalized difference snow index ndsi computations on tm images an estimate of the glacierized area in cordillera blanca peru was carried out for 1987 643 63 km2 and 1996 600 61 km2 compared to an estimate of 721 km2 in 1970 it can be concluded that the glacier area has retreated in this massif by more than 15 in 25 years

earthquake focal mechanisms deformation state and seismotectonics of the pamir tien shan region central asia this paper presents a review of the seismotectonics of the pamir tien shan collision zone in the garm region tajikistan based on geological structure seismicity and focal mechanism solutions the region is dominated by horizontal compression manifested by imbricate low angle thrust faults that separate the upper crust into a series of tectonic sheets these thrust systems verge northward from the tajik depression toward the southern tien shan and southward toward the northern pamir the pattern of seismicity across the region suggests that similar low angle thrust faults exist within the crystalline basement as well in order to reconstruct the present day stress strain state of the region we used data from over 15 000 earthquake focal mechanism solutions for small earthquakes m 1 0 gathered over the 27 year period 1963 1989 the method of reconstruction of the seismotectonic deformation std field involves dividing the data set into small spatial windows and summing the individual focal mechanism solutions to form an average earthquake mechanism tensor for each cell the std state of that cell can then be represented by the orientation of the principal axes of compression and tension the intensity or relative uniformity of the average mechanism and the lode nadai coefficient which defines the relation between the magnitudes of the principal strain components we observe throughout the study area a general predominance of subhorizontal compression manifested in a mixture of thrust and strike slip deformation normal fault deformation is observed in only two small portions of the study area the orientation of principal compression varies from nearly n s in the northern pamir and the southern tien shan to nw se in the peter the first range in general the std field has a clearly developed mosaic structure defined by spatial groupings of nearly uniform orientations of compression and tension axes the boundaries of these groups cannot in most cases be directly correlated with known geological contacts the std structure also shows some variation with depth with more or less uniform std orientation in the upper crust 0 14 km depth changing significantly at greater depths examination of various subsets of the focal mechanism catalog shows the spatial structure of the std field to be largely stable with respect to both time and magnitude the reliability of the reconstructed std field was verified using three approaches 1 comparison of individual focal mechanism determinations for a large subset of the data using both soviet and u s algorithms 2 comparison of std reconstruction results using the two independent focal mechanism catalogs and 3 examination of the effect of spatial sampling on the results the dominance of generally north oriented subhorizontal compression is interpreted to be primarily the result of convergence between the pamir and tien shan ranges in turn caused by the ongoing collision of india and eurasia

hydrothermal vents near a mantle hot spot the lucky strike vent field at 37 n on the mid atlantic ridge the lucky strike hydrothermal field occurs in the summit basin of a large seamount that forms the shallow center of a 65 km long ridge segment near 37 n on the mid atlantic ridge the depth and chemistry of the ridge segment are influenced by the azores hot spot and this hydrothermal field is the first atlantic site found on crust that is dominated by a hot spot signature multiple hydrothermal vents occur over an area of at least 300 m by 700 m vent morphologies range from flanges and chimneys with temperatures of 200 212 c to black smoker chimneys with temperatures up to 333 c cooler fluids from northern vents have higher chlorinities and lower gas volumes while hotter southern fluids have chlorinities 20 below seawater with higher gas volumes suggesting phase separation has influenced their compositions all gas volumes in fluids are higher than those at tag and snake pit hydrothermal fields black smokers exhibit their typical mineralogy except that barite is a major mineral particularly at lower temperature sites which contrasts with previously investigated atlantic sites the fluid chemistry distribution of the relict sulfide deposits on the seamount summit in the areas investigated using dsv alvin and contact relationships between active vent sites and surrounding basaltic and sulfide substrate suggest that the hydrothermal system has a long history and may have recently been rejuvenated fauna at the lucky strike vent sites are dominated by a new species of mussel and include the first reported sea urchins the lucky strike biological community differs considerably from other vent fauna at the species level and appears to be a new biogeographic province the lucky strike field helps to constrain how variations in the basaltic substrate influence the composition of hydrothermal fluids and solids because basalt compositions at lucky strike are 10 30 times enriched in incompatible elements compared to other atlantic hydrothermal sites such as tag snake pit and broken spur the incompatible element

a study of a flowslide with significant entrainment in loess areas in china flowslides are a frequent type of natural disaster in loess areas and may result in the significant loss of properties and or casualties the dagou flowslide is a typical event in a loess area and is accompanied by significant sediment entrainment to analyze the mechanisms responsible for flowslides and to obtain the parameters for a runout analysis a field investigation was conducted specimens were sampled on site to carry out laboratory tests including a triaxial test sieve analysis and chemical component analysis the parameters were used in the runout study employing an energy based runout model an analytical entrainment model was adopted to calculate the entrainment after considering physical properties and the mechanism of the entrainment process of the loess finally the entrainment model was incorporated into the runout model to simulate the post failure process of this case energy dissipation due to the deformation of slices was considered as it was thought to be important for a slide with a significant deformation the simulation results were compared with the measurements including runout distance total volume erosion depth deposition height at different sections and velocities at specific locations the results indicate that the energy based runout model together with the entrainment model can capture the kinematic characteristics of the dagou flowslide therefore it is feasible to use this model to predict the runout characteristics of flowslides in similar areas copyright c 2017 john wiley sons ltd

characteristics and remediation of a landslide complex triggered by the 2008 wenchuan china earthquake case from yingxiu near the earthquake epicenter during the 2008 wenchuan earthquake the river valley from yingxiu to wenchuan experienced numerous landslides and became a prominent area of landslide complexes the present large landslide complex near the earthquake epicenter consisted of laohuzui slide 1 laohuzui slide 2 and douyaping slide the scale geology morphology sliding process and failure mechanism of the landslide complex are analyzed by means of field investigation aerial photograph and stereographic projection technique characteristics of these three slides including seismic response of slope landslide debris damage and potential failure are discussed the convex slope and the upslope of fractured granitic rock at high altitude are highly prone to landsliding under earthquake the high source altitude and long travel path determine grain sizes and the deposit angle of the slide debris the landslide complex completely buries the g213 roadway and dams up the minjiang river in these sections after the earthquake rainfall aftershocks and river erosion may retrigger new failures such as retrogressive slide of weathered fractured rock colluvial landslide debris flow embankment failure and rockfall the following are presented as suggested remedial measures to protect the roadway and stabilize the slope the removing and trenching protective concrete rock blocks against erosion retaining structure rockfall stopping wall rockfall restraining net rock bolt and the planting of vegetation

extracting a climate signal from 169 glacier records i constructed a temperature history for different parts of the world from 169 glacier length records using a first order theory of glacier dynamics i related changes in glacier length to changes in temperature the derived temperature histories are fully independent of proxy and instrumental data used in earlier reconstructions moderate global warming started in the middle of the 19th century the reconstructed warming in the first half of the 20th century is 0 5 kelvin this warming was notably coherent over the globe the warming signals from glaciers at low and high elevations appear to be very similar

automatic delineation of debris covered glaciers using insar coherence derived from x c and l band radar data a case study of yazgyl glacier despite their importance for mass balance estimates and the progress in techniques based on optical and thermal satellite imagery the mapping of debris covered glacier boundaries remains a challenging task manual corrections hamper regular updates in this study we present an automatic approach to delineate glacier outlines using interferometrically derived synthetic aperture radar insar coherence slope and morphological operations insar coherence detects the temporally decorrelated surface e g glacial extent irrespective of its surface type and separates it from the highly coherent surrounding areas we tested the impact of different processing settings for example resolution coherence window size and topographic phase removal on the quality of the generated outlines we found minor influence of the topographic phase but a combination of strong multi looking during interferogram generation and additional averaging during coherence estimation strongly deteriorated the coherence at the glacier edges we analysed the performance of x c and l band radar data the c band sentinel 1 data outlined the glacier boundary with the least misclassifications and a type ii error of 0 47 compared with global land ice measurements from space inventory data our study shows the potential of the sentinel 1 mission together with our automatic processing chain to provide regular updates for land terminating glaciers on a large scale

a model for the runout analysis of rapid flow slides debris flows and avalanches runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows debris avalanches rockslide avalanches large scale liquefaction failure

upper crustal velocity structure beneath the central lucky strike segment from seismic refraction measurements we present a three dimensional velocity model of the upper crust around the central volcano of the lucky strike segment mid atlantic ridge the model constructed from a 3 d array of air gun shots 37 5 m spacing along line and 100 m between lines to ocean bottom seismometers fired during a 3 d seismic reflection survey shows an off axis velocity increase 1 km s a low velocity region within the median valley and a low velocity anomaly underneath the lucky strike volcano our observations indicate a porosity decrease of 1 9 corresponding to a velocity increase of 0 5 1 km s over a distance of 8 km from the ridge axis 0 7 ma and a porosity decrease of 4 11 corresponding to a velocity increase of 2 km s between a depth of 0 5 and 1 75 km below seafloor a sinusoidal variation in the traveltime residuals indicates the presence of azimuthal anisotropy with cracks aligned approximately along the ridge axis we favor an interpretation in which upper crustal porosities are created by a combination of magmatic accretion lava sheeted dike boundary and active extension faults fractures and fissures the porosity variation with depth probably depends on pore space collapse hydrothermal alteration and a change of stress accommodation the off axis porosities are possibly influenced by both hydrothermal precipitation and the aging of the crust

estimation of debris cover and its temporal variation using optical satellite sensor data a case study in chenab basin himalaya debris cover over glaciers greatly affects their rate of ablation and is a sensitive indicator of glacier health this study focuses on estimation of debris cover over samudratapu glacier chenab basin himalaya using optical remote sensing data remote sensing image data of irs 1c liss iii september 2001 irs p6 awifs september 2004 and terra aster september 2004 along with survey of india topographical maps 1963 were used in the study supervised classification of topographically corrected reflectance image data was systematically conducted to map six land cover classes in the glacier terrain snow ice mixed ice and debris debris valley rock and water an accuracy assessment of the classification was conducted using the aster visible near infrared data as the reference the overall accuracies of the glacier cover maps were found to range from 83 7 to 89 1 whereas the individual class accuracy of debris cover mapping was found to range from 82 to 95 this shows that supervised classification of topographically corrected reflectance data is effective for the extraction of debris cover in addition a comparative study of glacier cover maps generated from remote sensing data supervised classification of september 2001 and september 2004 and survey of india topographical maps 1963 has highlighted the trends of glacier depletion and recession the glacier snout receded by about 756 m from 1963 to 2004 and the total glacier area was reduced by 13 7 km 2 from 110 km 2 in 1963 further glacier retreat is found to be accompanied by a decrease in mixed ice and debris and a marked increase in debris cover area the area covered by valley rock is found to increase confirming an overall decrease in the glacier area the results from this study demonstrate the applicability of optical remote sensing data in monitoring glacier terrain and particularly mapping debris cover area

dense gnss profiles across the northwestern tip of the india asia collision zone triggered slip and westward flow of the peter the first range pamir into the tajik depression

the geochemical controls on vent fluids from the lucky strike vent field mid atlantic ridge abstract hydrothermal vent fluids were collected from the lucky strike site at 37 17 n on the mid atlantic ridge in both 1993 and 1996 seven vents were sampled with the dsv alvin in 1993 and six vents were sampled in 1996 using the rov jason during the lustre 96 cruise as three of the vents were sampled in both 1993 and in 1996 a time series of vent fluid chemistry is also reported measured temperatures ranged from 202 to 333 c at the 1618 1726 m depth of the vent field which is located on lucky strike seamount these fluids are either equal to or less than the local bottom seawater in chlorinity while the range in fluid compositions at lucky strike is generally within that observed elsewhere the unusual aspects of the fluid chemistries are the relatively high ph and low fe mn li and zn we attribute this as well as an usually low sr ca ratio to reaction with a highly altered substrate the high si and cu contents suggest a deep as well as hot source for these fluids the fluid compositions therefore suggest formation by super critical phase separation at a depth not less than 1300 m below the seafloor and reaction with a relatively oxic and previously altered substrate there is temporal variability in some of the vent fluid compositions as li k ca and fe concentrations have increased in some of the vents as has the fe mn molar ratio although the chlorinities have remained essentially constant from 1993 to 1996 while there is not a simple relationship between vent fluid compositions or temperatures and distance from the lava lake at the summit of the seamount the vent fluids from many of the vents can be shown to be related to others often at distances 200 m the most southeasterly vents eiffel tower and the marker mounds vents are distinct in chlorinity and other chemical parameters from the rest of the vents although closely related to each other within the southeastern area similarly all of the vents not in this one area appear closely related to each other this suggests one or two source fluids for many of the vents as is also inferred to be the case at tag but which is in contrast to observations on faster spreading ridges this may suggest inherently different plumbing for hydrothermal systems at slower versus faster spreading ridges

geotectonic setting of hydrothermal activity on the summit of lucky strike seamount 37 17 n mid atlantic ridge we have investigated the relations between volcanic tectonic and hydrothermal activity on lucky strike seamount 37 17 n mid atlantic ridge using a nested survey strategy involving collection of data from different deep sea mapping systems the highly tectonized seamount summit consists of three volcanic cones surrounding a relatively flat depression with a young lava lake in its center hydrothermal activity is focused mainly within the summit depression with most of the vents located proximal to the lava lake isolated active and inactive chimneys and mounds are widespread throughout the summit depression and occur on both volcanic pillow lava and hydrothermal sulfide rubble and hydrothermally cemented breccias substrates the large volume of sulfide rubble together with the nature of the sulfide structures indicates that hydrothermal activity has been episodic but ongoing for a long period of time hundreds to thousands of years on the basis of the distribution of hydrothermal deposits we propose a model of alternation between tectonic and volcanic control on hydrothermalism at lucky strike seamount midsegment melt focusing produces a spatially and temporally stable heat source that sustains focused high temperature hydrothermal activity over long time periods during periods of amagmatic extension active faulting within the summit depression provides multiple near surface fluid flow pathways for discharge of high temperature fluids and widespread deposition of massive sulfides during eruptive events rapid effusion of very hot lava creates a lava lake and hyaloclastite deposits the new sheet flows form a cap on the hydrothermal system and fluid upflow is reorganized discharge of high temperature fluids is restricted to isolated sites with relatively high permeability for example the edges of the lava lake much of the upwelling hydrothermal fluid pools in the subsurface conductively cools and mixes with entrained seawater before discharging as widespread low temperature diffuse flow hyaloclastites become cemented further augmenting the sealing of the system present day activity at lucky strike seamount represents this locally volcanically controlled phase of activity despite the segment as a whole being dominantly amagmatic

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

detecting himalayan glacial lake outburst floods from landsat time series abstract several thousands of moraine dammed and supraglacial lakes spread over the hindu kush himalayan hkh region and some have grown rapidly in past decades due to glacier retreat the sudden emptying of these lakes releases large volumes of water and sediment in destructive glacial lake outburst floods glofs one of the most publicised natural hazards to the rapidly growing himalayan population despite the growing number and size of glacial lakes the frequency of documented glofs is remarkably constant we explore this possible reporting bias and offer a new processing chain for establishing a more complete himalayan glof inventory we make use of the full seasonal archive of landsat images between 1988 and 2016 and track automatically where glofs left shrinking water bodies and tails of sediment at high elevations we trained a random forest classifier to generate fuzzy land cover maps for 2491 images achieving overall accuracies of 91 we developed a likelihood based change point technique to estimate the timing of glofs at the pixel scale our method objectively detected ten out of eleven documented glofs and another ten lakes that gave rise to previously unreported glofs we thus nearly doubled the existing glof record for a study area covering 10 of the hkh region remaining challenges for automatically detecting glofs include image insufficiently accurate co registration misclassifications in the land cover maps and image noise from clouds shadows or ice yet our processing chain is robust and has the potential for being applied on the greater hkh and mountain ranges elsewhere opening the door for objectively expanding the knowledge base on glof activity over the past three decades

assessing linkages between spatial facies changes and dimensional variations of glaciers in the upper indus basin western himalaya abstract the present study provides an insight into the heterogeneous response of 45 glaciers in the lidder and sindh river basins western himalaya and explores the linkages between glacier facies variability and changing glacier parameters results show that the region has undergone an overall deglaciation of 12 1 5 11 9 1 4 km 2 from 1996 to 2014 fluctuations in the temperature and precipitation patterns seem to be the primary factor controlling the changes in glacier dimensions r 2 0 82 in all cases glacier facies changes suggest depletion in snow ice cover 18 2 3 and an increase in ice mixed debris 4 1 4 supraglacial debris 6 1 5 and periglacial debris 17 1 2 these glacier facies transitions are possibly the result of ice melting however its relative rate and elevation decides the nature of facies conversion an increase in the proportion of supraglacial debris has led to the conversion of 11 clean glaciers to sparsely debris covered glaciers and 5 sparsely debris covered glaciers to debris covered glaciers the size of the glaciers greatly influenced the rate of conversion of glaciers and glaciers 2 dominated the others in this regard the small glaciers also experienced maximum shrinkage further the glaciers with varying supraglacial debris cover respond differently as sparsely debris covered glaciers exhibit the highest rates of retreat 25 7 3 m y followed by clean 23 7 7 3 m y and debris covered glaciers 13 1 7 3 m y thus the findings of this work clearly show that the climate change driven dimensional changes of glaciers and variations in the spatial distribution of glacier facies have strong mutual control on each other

the glaciers climate change initiative methods for creating glacier area elevation change and velocity products glaciers and their changes through time are increasingly obtained from a wide range of satellite sensors due to the often remote location of glaciers in inaccessible and high mountain terrain satellite observations frequently provide the only available measurements furthermore satellite data provide observations of glacier characteristics that are difficult to monitor using ground based measurements thus complementing the latter in the glaciers cci project of the european space agency esa three of these characteristics are investigated in detail glacier area elevation change and surface velocity we use a data from optical sensors to derive glacier outlines b digital elevation models from at least two points in time c repeat altimetry for determining elevation changes and d data from repeat optical and microwave sensors for calculating surface velocity for the latter the two sensor types provide complementary information in terms of spatio temporal coverage while c and d can be generated mostly automatically a and b require the intervention of an analyst largely based on the results of various round robin experiments multi analyst benchmark studies for each of the products we suggest and describe the most suitable algorithms for product creation and provide recommendations concerning their practical implementation and the required post processing for some of the products area velocity post processing can influence product quality more than the main processing algorithm

landslides triggered by the 1949 khait earthquake tajikistan and associated loss of life abstract earthquake triggered landslides are a major geological hazard in central asia in july 1949 the m7 4 khait earthquake triggered many hundreds of landslides in a mountainous region near the southern limit of the tien shan mountains central tajikistan these landslides involved widespread rock slope failure as well as large numbers of flowslides in loess that mantles the steep slopes of the region in the yasman valley hundreds of loess landslides coalesced to form a massive loess flow est vol 245 mm 3 that travelled up to 20 km on a slope of only 2 in an adjacent valley the khait landslide involved transformation of an earthquake triggered rockslide into a very rapid flow by the entrainment of saturated loess into its movement it travelled 7 41 km over a vertical distance of 1421 m with an estimated average velocity of 30 m s we estimate its volume as 75 mm 3 an order of magnitude less that previously published estimates the khait landslide was simulated using dan the number of casualties due to earthquake triggered landslides in the epicentral region was considerable approximately 4000 people were killed in the yasman valley loess flow as 20 villages kishlaks were overwhelmed in the khait landslide alone we estimate ca 800 people lost their lives when the villages of khait and khisorak were overrun by rapidly moving debris our data indicates that a total of approximately 7200 people were killed by earthquake triggered landslides in the epicentral region of the khait earthquake and that in terms of loss of life the 1949 yasman valley loess flow was one of the most destructive landslides in recent history

spectral signature of alpine snow cover from the landsat thematic mapper mapping of snow and estimation of snow characteristics from satellite remote sensing data require that we distinguish snow from other surface cover and from clouds and compensate for the effects of the atmosphere and rugged terrain the spectral signature of the snowpack is calculated from a radiative transfer model accounting for scattering and absorption by the ice grains water inclusions and particulates in interpreting the spectral reflectance measured from the thematic mapper or from any other satellite we need to account for topographic effects without requiring that satellite data be precisely registered to digital elevation data because the poor quality of most digital elevation data introduces considerable noise into calculations of slope and azimuth for a range of snow types atmospheric profiles and topographic illumination conditions i estimate typical spectral signatures for the landsat thematic mapper tm images of the southern sierra nevada are analyzed to distinguish several classes of snow from other surface covers snow can be reliably distinguished from other surfaces and from clouds at all sun angles encountered in the mid latitudes in tm band 1 or 2 snow is brighter than other natural surfaces and in band 5 clouds are usually much more reflective than snow therefore the intersection of the following criteria maps the snow cover planetary reflectance rp in tm band 1 is greater than about 0 16 rp tm5 is less than about 0 2 the normalized band 2 5 difference rp tm2 rp tm5 rp tm2 rp tm5 is greater than about 0 4 large surface grain sizes can be distinguished from areas where the grain size is finer at the snow surface using tm bands 2 4 and 5 because of saturation in tm band 1 estimation of the degree of contamination by absorbing aerosols is not feasible rp tm2 rp tm5 rp tm2 rp tm5 is

structure temporal evolution and heat flux estimates from the lucky strike deep sea hydrothermal field derived from seafloor image mosaics 1 here we demonstrate with a study of the lucky strike hydrothermal field that image mosaicing over large seafloor areas is feasible with new image processing techniques and that repeated surveys allow temporal studies of active processes lucky strike mosaics generated from 56 000 images acquired in 1996 2006 2008 and 2009 reveal the distribution and types of diffuse outflow throughout the field and their association with high temperature vents in detail the zones of outflow are largely controlled by faults and we suggest that the spatial clustering of active zones likely reflects the geometry of the underlying plumbing system imagery also provides constraints on temporal variability at two time scales first based upon changes in individual outflow features identified in mosaics acquired in different years we document a general decline of diffuse outflow throughout the vent field over time scales up to 13 years second the image mosaics reveal broad patches of seafloor that we interpret as fossil outflow zones owing to their association with extinct chimneys and hydrothermal deposits these areas encompass the entire region of present day hydrothermal activity suggesting that the plumbing system has persisted over long periods of time loosely constrained to hundreds to thousands of years the coupling of mosaic interpretation and available field measurements allow us to independently estimate the heat flux of the lucky strike system at 200 to 1000 mw with 75 to 90 of this flux taken up by diffuse hydrothermal outflow based on these heat flux estimates we propose that the temporal decline of the system at short and long time scales may be explained by the progressive cooling of the amc without replenishment the results at lucky strike demonstrate that repeated image surveys can be routinely performed to characterize and study the temporal variability of a broad range of vent sites hosting active processes e g cold seeps hydrothermal fields gas outflows etc allowing a better understanding of fluid flow dynamics from the sub seafloor and a quantification of fluxes

automated mapping of montane snow cover at subpixel resolution from the landsat thematic mapper a fully automated method uses landsat thematic mapper data to map snow cover in the sierra nevada and make quantitative estimates of the fractional snow covered area within each pixel we model winter and spring reference scenes as linear mixtures of image end member spectra to produce the response variables for tree based regression and classification models decision trees identify cloud cover and fractional snow covered area we test the algorithm on a different thematic mapper scene and verify with high resolution large format color aerial photography the accuracy of the automated classification of thematic mapper data equals that obtainable from the aerial photographs but is faster cheaper and covers a vastly larger area the mapping method is insensitive to the choice of lithologic or vegetation end members the water equivalent of the snow pack snow grain size or local illumination angle

channelized lava flows at the east pacific rise crest 9 10 n the importance of off axis lava transport in developing the architecture of young oceanic crust 1 submarine lava flows are the building blocks of young oceanic crust lava erupted at the ridge axis is transported across the ridge crest in a manner dictated by the rheology of the lava the characteristics of the eruption and the topography it encounters the resulting lava flows can vary dramatically in form and consequently in their impact on the physical characteristics of the seafloor and the architecture of the upper 50 500 m of the oceanic crust we have mapped and measured numerous submarine channelized lava flows at the east pacific rise epr crest 9 10 n that reflect the high effusion rate and high flow velocity end member of lava eruption and transport at mid ocean ridges channel systems composed of identifiable segments 50 1000 m in length extend up to 3 km from the axial summit trough ast and have widths of 10 50 m and depths of 2 3 m samples collected within the channels are n morb with mg indicating eruption from the ast we produce detailed maps of lava surface morphology across the channel surface from mosaics of digital images that show lineated or flat sheets at the channel center bounded by brecciated lava at the channel margins modeled velocity profiles across the channel surface allow us to determine flux through the channels from 0 4 to 4 7 103 m3 s and modeled shear rates help explain the surface morphology variation we suggest that channelized lava flows are a primary mechanism by which lava accumulates in the off axis region 1 3 km and produces the layer 2a thickening that is observed at fast and superfast spreading ridges in addition the rapid high volume flux eruptions necessary to produce channelized flows may act as an indicator of the local magma budget along the epr we find that high concentrations of channelized lava flows correlate with local across axis ridge morphology indicative of an elevated magma budget additionally in locations where channelized flows are located dominantly to the east or west of the ast the ridge crest is asymmetric and layer 2a appears to thicken over a greater distance from the ast toward the side of the ridge crest where the channels are located

detecting rock glacier flow structures using gabor filters and ikonos imagery abstract while ridges and furrows on the surface of rock glaciers are probably the most characteristic morphological features of this expression of creeping mountain permafrost this is the first study that examines the utility of texture filters in detecting rock glacier flow structures texture features were derived from a gabor filterbank applied to two panchromatic ikonos orthoimages from the chilean andes and terrain attributes were obtained in order to narrow down the area of interest and as additional predictor variables four classification methods of different complexity generalized linear model glm generalized additive model gam support vector machine svm bundling were applied to three sets of predictor variables texture attributes terrain attributes and the combination of both and predictive performances were estimated using two spatial cross validation strategies in terms of the median area under the roc receiver operating characteristics curve auroc overall classifiers utilizing texture attributes alone or usually even better in combination with terrain attributes outperformed terrain attributes alone and bundling in most cases followed by svm showed the overall best performance as a classification method cross validated median auroc values were mostly between 0 70 and 0 80 or fair in this focused pilot study but much better results are to be expected at the landscape scale permutation based spatial variable importance measures indicate that gabor features corresponding to texture wavelengths between 10 and 30 m are the most important predictors which is consistent with typical ridge spacing on rock glaciers confounding occurred mostly in areas with linear erosion features and ridges or scarps in morainic and thermokarst terrain we suggest that texture filters and the chosen methodological approach are relevant not only for rock glacier mapping but also for delineating debris covered glaciers and characterizing glacier surfaces as well as for other geomorphological and cryospheric applications

the problem of hidden ice in glacier mapping lee can become hidden i e buried by the superimposition of rock debris on a glacier or where rock debris may incorporate interstitial ice because it is obscured problems result from a lack of understanding of the extent and continued activity of such ice landforms may be associated with this phenomenon and can be used as indirect evidence of its existence a rock glacier can contain glacially derived buried ice as well as interstitial ice we show with examples how such rock glaciers can be identified and provide information on the extent and possible volume of hidden ice in marginally glacierized and permafrost areas in most cases recognition of topography is sufficient although time separated aerial photographs may be necessary to locate the extent of ice these are generally preferable to and more cost effective than most detailed on site determinations of ice extent it is possible to incorporate and extend knowledge of hidden ice in glacier mapping and inventory projects

hydrothermal activity along the slow spreading lucky strike ridge segment mid atlantic ridge distribution heatflux and geological controls we have reviewed available visual information from the seafloor and recently acquired microbathymetry for several traverses across the lucky strike segment to evaluate the distribution of hydrothermal activity we have identified a new on axis site with diffuse flow ewan and an active vent structure similar to 1 2 km from the axis capelinhos these sites are minor relative to the main field and our total heatflux estimate for all active sites 200 1200 mw is only slightly higher than previously published estimates we also identify fossil sites w of the main lucky strike field a circular feature similar to 200 m in diameter located on the flanks of a rifted off axis central volcano is likely a large and inactive hydrothermal edifice named grunnus we find no indicator of focused hydrothermal activity elsewhere along the segment suggesting that the enhanced melt supply and the associated melt lenses required to form central volcanoes also sustain hydrothermal circulation to form and maintain large and long lived hydrothermal fields hydrothermal discharge to the seafloor occurs along fault traces suggesting focusing of hydrothermal circulation in the shallow crust along permeable fault zones

the second chinese glacier inventory data methods and results the second chinese glacier inventory was compiled based on 218 landsat tm etm scenes acquired mainly during 2006 10 the widely used band ratio segmentation method was applied as the first step in delineating glacier outlines and then intensive manual improvements were performed the shuttle radar topography mission digital elevation model was used to derive altitudinal attributes of glaciers the boundaries of some glaciers measured by real time kinematic differential gps or digitized from high resolution images were used as references to validate the accuracy of the methods used to delineate glaciers which resulted in positioning errors of 10 m for manually improved clean ice outlines and 30 m for manually digitized outlines of debris covered parts the glacier area error of the compiled inventory evaluated using these two positioning accuracies was 3 2 the compiled parts of the new inventory have a total area of 43 087 km 2 in which 1723 glaciers were covered by debris with a total debris covered area of 1494 km 2 the area of uncompiled glaciers from the digitized first chinese glacier inventory is similar to 8753 km 2 mainly distributed in the southeastern tibetan plateau where no images of acceptable quality for glacier outline delineation can be found during 2006 10

surficial permeability of the axial valley seafloor endeavour segment juan de fuca ridge 1 hydrothermal systems at mid ocean spreading centers play a fundamental role in earth s geothermal budget one underexamined facet of marine hydrothermal systems is the role that permeability of the uppermost seafloor veneer plays in the distribution of hydrothermal fluid as both the initial and final vertical gateway for subsurface fluid circulation uppermost seafloor permeability may influence the local spatial distribution of hydrothermal flow a method of deriving a photomosaic from seafloor video was developed and utilized to estimate relative surface permeability in an active hydrothermal area on the endeavour segment of the juan de fuca ridge the mosaic resolves seafloor geology of the axial valley seafloor at submeter resolution over an area greater than 1 km2 results indicate that the valley walls and basal talus slope are topographically rugged and unsedimented providing minimal resistance to fluid transmission elsewhere the axial valley floor is capped by an unbroken blanket of low permeability sediment resisting fluid exchange with the subsurface reservoir active fluid emission sites were restricted to the high permeability zone at the base of the western wall a series of inactive fossil hydrothermal structures form a linear trend along the western bounding wall oriented orthogonal to the spreading axis high temperature vent locations appear to have migrated over 100 m along ridge strike over the decade between surveys while initially an expression of subsurface faulting this spatial pattern suggests that increases in seafloor permeability from sedimentation may be at least a secondary contributing factor in regulating fluid flow across the seafloor interface

subseafloor phase equilibria in high temperature hydrothermal fluids of the lucky strike seamount mid atlantic ridge 37 17 n abstract as part of an integrated study conducted at the lucky strike seamount mid atlantic ridge 37 17 n in 2008 gas tight sampling devices were used to collect high temperature 300 c hydrothermal fluids issuing from sulfide structures distributed throughout the vent field located in the summit depression compared with previous observations from 1993 to 1997 the most substantial changes in vent fluid compositions are dramatically increased co2 concentrations 5 up to 133 mmol l and the observation of vent fluids enriched in dissolved chloride relative to seawater combined with an increase in 13 c co 2 values by 4 in 2008 the elevated co2 indicates replenishment of the magmatic heat source and may be indicative of a recent magmatic event the additional supporting fluid chemistry is however similar to that of the previous sampling intervals necessitating a reassessment of the subseafloor controls on vent fluid chemistry at lucky strike in the context of recently obtained geophysical data that provides the depth extent of a steady state magma chamber two phase behavior is indicated by the chloride variability in the vent fluids and comparison with experimental data for the associated chloride dependent partitioning of minor trace elements suggests the possibility of a similar source fluid for all the vent structures while limiting the likelihood of shallow phase separation and subseafloor mixing for the hydrothermal end members a recently calibrated fe mn geothermometer indicates minimum subseafloor equilibration temperatures of 350 385 c however constraints imposed by dissolved si cl in conjunction with geophysical observations are consistent with peak reaction conditions at temperatures of 430 475 c and pressures near the top of the axial magma chamber 410 480 bars where magmatic co2 becomes entrained in the circulating fluids the distance between the magma chamber and the seafloor at lucky strike is substantially greater than at most faster spreading ridges and we propose the resulting increased residence time in the up flow zone leads to the re equilibration of temperature sensitive transition metals at conditions less extreme than those associated with peak reaction agreement between experimental data thermodynamic model calculations and dissolved concentrations of fe cu zn h2 and h2s in the lucky strike fluids reinforce the hypothesis of ph redox equilibria for transition metals at relatively oxidizing conditions and temperatures predicted by the empirical fe mn geothermometer in situ ph measurements of the high temperature fluids exiting the seafloor are also consistent with the model calculations

reflectances of glaciers as calculated using landsat 5 thematic mapper data landsat 5 thematic mapper tm data have been used in previous work in order to locate zones of similar spectral reflectance on glaciers in austria and alaska and to relate these zones to the glacier facies which are indicative of glacier mass balance in this paper landsat 5 digital numbers dns have been used to compute the at satellite planetary reflectances p on spectrally similar zones on the meares and schwanda glaciers in alaska and the grossglockner glacier group in austria the patterns of tm derived reflectances in the ablation areas of the grossglockner glacier group and the meares glacier compare favorably with published reflectance curves measured on the surface of glacier ice though the surface reflectance of snow covered ice is higher than the landsat derived reflectance for the glaciers studied the accuracy of the at satellite planetary reflectances is shown to be affected by topographic and atmospheric effects and by the anisotropic nature of snow reflectance use of reflectance values for analysis of snow and ice facilitates scene to scene comparisons of glaciers

planimetric and volumetric glacier changes in the khumbu himal nepal since 1962 using corona landsat tm and aster data multitemporal space imagery from 1962 corona kh 4 1992 landsat tm 2001 and 2005 terra aster was used to investigate the glacier changes in the khumbu himal nepal the ice coverage in the investigation area decreased by about 5 between 1962 and 2005 with the highest retreat rates occurring between 1992 and 2001 the debris coverage increased concomitantly with the decrease in total glacier area the clean ice area decreased by 10 digital terrain model dtm generation from the early corona kh 4 stereo data in this high relief terrain is time consuming and the results still contain some elevation errors however these are minor in the snow free areas with gentle slopes thus comparison of the surfaces of the debris covered glacier tongues based on the corona dtm and an aster dtm is feasible and shows the downwasting of the debris covered glaciers the highest downwasting rates more than 20 m 0 5 m a 1 can be found near the transition zone between the active and the stagnant glacier parts of the debris covered glacier tongues the downwasting is lower but still evident in the active ice areas and at the snout with thick debris cover all investigated debris covered glaciers in the study area show similar behaviour the estimated volume loss for the investigated debris covered glacier tongues is 0 19 km 3

crustal velocity structure of the lucky strike segment of the mid atlantic ridge at 37 n from seismic refraction measurements we estimate the seismic structure of the slow spreading lucky strike segment of the mid atlantic ridge located approximately 300 km south of the azores platform using seismic reflection and seismic refraction data acquired in june 2005 as a part of the seismic study for monitoring of the mid atlantic ridge sismomar survey the three dimensional velocity model shows an upper crustal low velocity anomaly running parallel to the ridge axis which is limited by the median valley bounding faults the velocity models also show a low velocity anomaly underlying the axial melt lens reflector located at the segment center below the lucky strike volcano this lower crustal low velocity region can be explained by elevated temperatures and possibly small amounts of melt the lower crustal low velocity anomaly and the axial melt lens reflector constrain the geometry of the magma chamber responsible for the construction of the lucky strike volcano the presence of this magma chamber and thick crust at the segment center are consistent with a focused melt supply to the segment center

compared geochemical signatures and the evolution of menez gwen 37 50 n and lucky strike 37 17 n hydrothermal fluids south of the azores triple junction on the mid atlantic ridge during the diva 1 cruise in may 1994 a series of 19 dives was conducted using the french submersible nautile at the topographic highs of three volcanic segments centered at 37 17 n 37 50 n and 38 20 n respectively south of the azores triple junction atj on the mid atlantic ridge mar hydrothermal fluids were collected at the lucky strike ls hydrothermal field discovered at 37 17 n in 1993 and at a new hydrothermal site called menez gwen mgw discovered at 37 50 n during this cruise both systems are relatively shallow compared to other mar systems with seafloor depths of 1700 and 850 m respectively characteristics which make them unique among the already known sites on the mar the characteristics of the ls fluids are the same as in 1993 and include temperatures ranging from 170 c to 324 c variable chlorinities lower than seawater low hydrogen sulfide 3 0 mmol kg high ba concentrations up to 80 mol kg low metal concentrations and high gas contents and distinct chemical end members indicative of significant geographic control of the venting system in contrast the very clear mgw fluids at 37 50 n show a rather uniform exit temperature 285 c and chemical compositions with chlorinities 360 380 mmol kg lower than at ls and corresponding lower concentrations of cations h2s 1 8 mmol kg metals and silica 8 11 5 mmol kg due to the lower temperature t and pressure p of the system in the two systems fluid chemistry is strongly affected by phase separation at the low pressure conditions of these sites phase relations in the nacl h2o system dictate production of an extremely low salinity the higher salinities observed in fluids thus indicate that mixing of extremely low salinity vapor with single phase hydrothermal seawater is the dominant process controlling cl concentrations depletions and enrichments of elements in solutions are also explained by the involvement of fluid rock reactions the enrichment of ba k cs and rb in the fluids is linked to the enriched character of these elements in basalts relatively high ph and ca low li sr and metals are related to the highly altered basaltic substrate in the reaction zone low sr ca and high ca na ratios are explained by albitization within the crust the increase of degassing when approaching the azores may be related to the carbon enriched basaltic crust near the azores hot spot isotopic ratios show that co2 ch4 and helium gases have a magmatic signature compared to other deeper sites on the mar all fluids collected at ls and mgw are gas enriched except for h2s and helium whose both concentration and isotopic ratio compare well with other hydrothermal fluids the high ch4 concentration associated with unsaturated hydrocarbons and the high ch4 3he ratios also suggest a contribution of ch4 generated by serpentinization of ultramafic rocks by fischer tropsch catalysis of co2 reduction