basin morphology and seismic stratigraphy of lake kotokel baikal region russia the basin of lake kotokel located along the eastern shore of lake baikal russia has attracted several scientific projects to investigate the climate vegetation and lake history throughout the late pleistocene and holocene however little was known about its basin structure and sediment architecture echo sounding and 3 5 khz single frequency sub bottom profiling were used to decipher the basin morphology and seismic stratigraphy to a depth of approximately 50 m the bathymetric map shows a very shallow lake of 4 m mean water depth and an almost flat lake bottom a distinct elongated small sized depression of up to 12 m water depth between the north western coast and a small island developed along an nw se oriented fault line a total of 46 km of seismic profiles crossing the lake along 12 transects shows that the bottom sediments consist of three different facies which accords to previously analyzed core sequences several distortions of sediment layers at various sites indicate tectonically induced impact which resulted in up to 3 m vertical offsets of sediment packages at local sites the offsets indicate a probably still active fault along the western shoreline of the lake soft gyttja of the upper 6 m does not show distortions and may have obscured potential younger tectonic activity the sediments date to the late pleistocene small updoming features along the boundary between layers i and ii may be assigned to degassing processes or to seismic activity river channel fills along the north eastern coast are indicative of a lower lake level prior to 15 ka bp the sediment stratigraphy indicates that suitable coring sites for paleoclimate studies are only located in the southern part of the basin where almost undisturbed sediments can be expected

palaeo moisture evolution in monsoonal central asia during the last 50 000 years abstract the late quaternary climate history of monsoonal central asia was inferred from 75 palaeoclimatic records which provide information about moisture conditions in the last 50 ka or part of this period wet conditions occurred during middle and late marine isotope stage 3 while the last glacial maximum lgm was characterized by dry climate conditions in the region a stepwise climate amelioration is suggested by the climate records following the lgm several climate signals of this period which were reported from high latitude ice core records are preserved in archives from monsoonal central asia as well during the early holocene high effective moisture was inferred from most records from the area dominated by the indian monsoon e g the tibetan plateau suggesting that holocene optimal climate conditions occurred there during this period in contrast areas which are dominated by the south east asian monsoon se monsoon and the westerlies in north western and north central china mongolia do not uniformly show an early holocene climate optimum for this area optimal conditions prevailed during the mid holocene these apparent contradictions can possibly be explained by the regional uplift and descent of air masses in the holocene during the early holocene strengthened insolation possibly caused an enhanced low level convergence over the tibetan plateau which led to the intensification of the summer monsoon the strong air uplift caused intensified precipitation and air divergence in the upper troposphere over the tibetan plateau the areas adjacent to the north therefore experienced an intensified descent of air masses and consequently increased aridity the majority of the palaeoclimatic records suggest reduced effective moisture since the late holocene in the region

using cosmo skymed x band and envisat c band sar interferometry for landslides analysis abstract we explore new possibilities offered by the recently available x band satellite radar sensors for landslide hazard assessments on a detailed scale with particular reference to the exploitation of persistent scatterers interferometry psi techniques special attention is paid to the impact of the improved resolution of new x band radar imagery on the psi results in terms of quality and quantity of useful information this evaluation is supported by theoretical modelling as well as by the comparison of results from x band csk and c band envisat psi for two areas of interest one in italy and the other in switzerland it is demonstrated that with respect to medium resolution envisat ps processing fewer csk high resolution images are sufficient to achieve comparable precision of the mean displacement velocity estimates this together with the shorter revisit times provided by the csk constellation can be very important when dealing with emergency situations furthermore it is quantified that from about 3 to 11 times greater ps densities are obtained with the higher resolution x band data this implies more information about ground surface displacements as well as improved landslide monitoring and slope instability investigation capabilities furthermore ground displacement measurements can be interpreted without local knowledge of the focus area or in situ controls and nonetheless guide single hillslope instability assessments with support of google earth and its high resolution optical imagery this blind approach will allow one to monitor remote and poorly known regions at high risk of potentially disastrous slope failures

modelling differential catchment response to environmental change the caesar cellular automaton evolutionary slope and river model is used to demonstrate significant differences in coarse sediment transfer and alluviation in medium sized catchments when responding to identical holocene environmental changes simulations for four u k basins the rivers swale ure nidd and wharfe shows that catchment response driven by climate and conditioned by land cover changes is synchronous but varies in magnitude there are bursts of sediment transfer activity generally of rapid removal but with some sediment accumulation dspikest with longer periods of slow removal or accumulation of sediment in different valley reaches within catchments reach sensitivity to environmental change varies considerably some periods are only recorded in some reaches whilst higher potential sensitivity typically occurs in the piedmont areas of the catchments modelled here these differential responses appear to be highly non linear and may relate to the passage of sediment waves by variable local sediment storage and availability and by large and small scale thresholds for sediment transfer within each catchment differential response has major implications for modelling fluvial systems and the interpretation of field data model results are compared with the record of dated alluvial deposits in the modelled catchments d 2005 elsevier b v all rights reserved

paleoglaciation of the tibetan plateau and surrounding mountains based on exposure ages and ela depression estimates the tibetan plateau holds an ample record of past glaciations and there is an extensive set of glacial deposits dated by exposure dating here a compilation is presented of 10be exposure ages from 485 glacial deposits with 1855 individual samples on the tibetan plateau and ela depression estimates for the glacial deposits based on a simple toe to headwall ratio approach to recalculate the tibetan plateau exposure ages 10be production rates from 24 calibration sites across the world are compiled and recalibrated yielding an updated global reference 10be production rate the recalculated exposure ages from the tibetan plateau glacial deposits are then divided into three groups based on exposure age clustering to discriminate good well clustered from poor scattered deglaciation ages a major part of the glacial deposits have exposure ages affected by prior or incomplete exposure complicating exposure age interpretations the well clustered deglaciation ages are primarily from mountain ranges along the margins of the tibetan plateau with a main peak between 10 and 30 ka indicating glacial advances during the global lgm a large number of deglaciation ages older than 30 ka indicates maximum glaciation predating the lgm but the exposure age scatter generally prohibits accurate definition of the glacial chronology the ela depression estimates scatter significantly but the main part is remarkably low average ela depressions of 337 197 m for the lgm and 494 280 m for the pre lgm indicate restricted glacier expansion

accelerated lake expansion on the tibetan plateau in the 2000s induced by glacial melting or other processes ccelerated lake expansion in the 2000s has been confirmed by both dramatic lake area increases for 312 lakes larger than 10 km2 derived from optical images and rapid water level rises for 117 lakes with water level data measured by satellite altimetry however the underlying climate causes remain unclear this paper analyzes the relationship between the water level changes of lakes on the plateau and the potential driving factors such as the glacier meltwater supply and a dependency on precipitation and runoff over the whole plateau and in each zone the results show that the rates of change of non glacier fed lakes in the 2000s were as high as those of glacier fed lakes across the whole plateau and the lake level changes were closely associated with the lake supply coefficients the basin lake area ratio the lake variations agreed well with the spatial pattern of precipitation changes however in different zones especially at around 33 n north of the plateau glacier fed lakes did exhibit faster lake level increases than no glacier fed lakes indicating that the presence of a glacier meltwater supply augmented the precipitation driven lake expansions in these areas despite the absence of quantitative modeling due to limited data availability this study provides qualitative support that the lake expansions on the tibetan plateau in the 2000s have been driven primarily by changes in precipitation and evapotranspiration and not solely by the effect of glacier wastage

global vegetation dynamics and latitudinal temperature gradients during the mid to late miocene 15 97 5 33 ma a 617 site palaeobotanical dataset for the mid to late miocene is presented this dataset is internally consistent and provides a comprehensive overview of vegetational change from 15 97 to 5 33 ma the palaeobotanical dataset has been translated into the biome4 classification scheme to enable direct comparison with climate model outputs the vegetation change throughout the langhian seravallian tortonian and messinian is discussed the data shows that the langhian which includes the end of the mid miocene climatic optimum represents a world significantly warmer than today the high northern latitudes were characterised by cool temperate forests the mid latitudes by warm temperate mixed forests the tropics by tropical evergreen broadleaf forests and antarctica by tundra shrub vegetation cool temperate mixed forest existed during the seravallian in the high northern latitudes a reduction in warm temperate mixed forests in the mid latitudes and a loss of tundra on antarctica was noted tortonian vegetation distribution indicates that further cooling had occurred since the seravallian the major changes in vegetation include the first evidence for cold taiga forest in the high northern latitudes and a further reduction of warm temperate mixed forests by the messinian this cooling trend had eliminated warm temperate mixed forests from the western usa and australia and had formed mid latitude deserts despite the cooling trend throughout the mid to late miocene the vegetation distribution of all four reconstructed stages reflect the vegetation of a world warmer than the pre industrial conditions the latitudinal distribution of bioclimatic zones suggests that the latitudinal temperature gradient for the langhian would have been significantly shallower than at present and has gradually but asymmetrically become more modern towards the end of the miocene first the southern hemisphere distribution of bioclimatic zones became more modern probably due to the climatic effects of a fully glaciated antarctica the northern hemisphere bioclimatic zone gradient continued to be shallower than modern throughout the miocene and slowly became more modern by the messinian

long term versus short term deformation processes at tenerife canary islands 1 several geophysical investigations have identified that the tenerife volcanic complex is affected by crustal deformation processes occurring at timescales of millions of years recently space based geodetic observations have also detected a short term surface deformation characterized by a broad subsidence pattern with maximum ground velocities of about 4 mm yr 1 for the purpose of investigating the relationship between these long term and short term deformation processes we performed an advanced fluid dynamic analysis fda we first carried out a standard dimensionless fda to discriminate the deformation style of tenerife and found that at million year timescales basement flexure mainly controls its long term structural evolution secondly to highlight the driving forces of the short term deformation process we simulated a numerical fda based on finite element models that include topography as well as vertical and lateral material heterogeneities our results show that the recent surface deformation is mainly caused by a progressive sagging of the denser less viscous core of the island onto the weaker but more viscous lithosphere moreover over periods comparable to the hypothesized age of loading of the oceanic crust beneath tenerife this tendency would result in a total flexure of about 3 4 km which is in agreement with independent estimations based on geophysical analyses our study shows that a unitary physical model may explain both the deformation recorded in deep geological structures and the current active ground deformation processes occurring at the tenerife volcano

model for predicting the variation of shear stress in unsaturated soils during strain softening several of the geotechnical structures constructed with unsaturated soils undergo a large deformation prior to reaching failure conditions e g progressive failure of a soil slope during this pr

the displacement field of the landers earthquake mapped by radar interferometry geodetic data obtained by ground or space based techniques can be used to infer the distribution of slip on a fault that has ruptured in an earthquake although most geodetic techniques require a surveyed network to be in place before the earthquake1 3 satellite images when collected at regular intervals can capture co seismic displacements without advance knowledge of the earthquake s location synthetic aperture radar sar interferometry first introduced4 in 1974 for topographic mapping5 8 can also be used to detect changes in the ground surface by removing the signal from the topography9 10 here we use sar interferometry to capture the movements produced by the 1992 earthquake in landers california11 we construct an interferogram by combining topographic information with sar images obtained by the ers 1 satellite before and after the earthquake the observed changes in range from the ground surface to the satellite agree well with the slip measured in the field with the displacements measured by surveying and with the results of an elastic dislocation model as a geodetic tool the sar interferogram provides a denser spatial sampling 100 m per pixel than surveying methods1 3 and a better precision 3 cm than previous space imaging techniques12 13

centrifuge model testing of a loess landslide induced by rising groundwater in northwest china abstract considerable artificial irrigation in the heifangtai area has caused the continued rise of groundwater levels which has resulted in several large scale landslides in the loess platform area considering the no 13 landslide of jiaojia in the heifangtai area as a geological archetype a series of centrifuge tests was conducted to study the deformation and failure characteristics of the slope due to the continuous rise in the groundwater level meanwhile the pore water pressure earth pressure deformation and evolution characteristics of the slope were monitored and recorded in real time furthermore isotropically consolidated undrained triaxial testing icu was conducted to investigate the static liquefaction of loess specimens which was related to the slope instability the centrifuge test results showed that a series of parallel and steep tension cracks at the top of the slope were present before the landslide which was caused by the rising groundwater the icu experimental results showed that as the pore water pressure increased strong strain softening and static liquefaction of saturated loess soils were found which was related to the sudden destruction of the slope

quaternary base level drops and trigger mechanisms in a closed basin geomorphic and sedimentological studies of the gastre basin argentina abstract evaluating the role of tectonics and climate as possible triggering mechanisms of landscape reconfigurations is essential for paleoenvironmental and paleoclimatic reconstructions in this study an exceptional receptive closed quaternary system of patagonia the gastre basin is described and examined in order to analyze factors triggering base level drops based on a geomorphological approach which includes new tectonic geomorphology investigations combined with sedimentological and stratigraphic analysis three large scale geomorphological systems were identified described and linked to two major lake level highstands preserved in the basin the results indicate magnitudes of base level drops that are several orders of magnitude greater than present day water level fluctuations suggesting a triggering mechanism not observed in recent times direct observations indicating the occurrence of quaternary faults were not recorded in the region in addition morphometric analyses that included mountain front sinuosity valley width height ratio and fan apex position dismiss tectonic fault activity in the gastre basin during the middle pleistocene holocene therefore we suggest here that upper pleistocene climate changes may have been the main triggering mechanism of base level falls in the gastre basin as it is observed in other closed basins of central patagonia i e carri laufquen basin

cosmogenic 10be and 26al dating of paleolake shorelines in tibet abstract we have used in situ produced cosmogenic nuclides 10be and 26al to date lacustrine shorelines around eight lakes in tibet two lakes located south of the yarlung tsangpo river discharged at high lake levels one of them drolung co co is a local term meaning lake became closed its water level fell below its outlet channel at 3 8 ka and lowered over 120 m vertically since then this implies a significant change in intensity of precipitation driven by the indian monsoon over southern tibet in the middle late holocene nam co and dajia co located to the north of the yarlung tsangpo river also drained at high lake levels and became closed 53 36 ka and 48 ka respectively of four other lakes developed closely in the qiangtang basin north of the yarlung tsangpo river tangra yum co and siling co located at 31 32 n show exposure ages for high lake shorelines of over 220 ka the oldest lake shorelines reported for tibet while towards the north and west the high lake of zhari nam co appeared after the last glacial maximum lgm the different pattern of lake development to the north of yarlung tsangpo river may reflect regional climate effects

from previous c band to new x band sar systems assessment of the dinsar mapping improvement for deformation time series retrieval in urban areas we investigate the capability improvement of the advanced differential interferometric synthetic aperture radar dinsar techniques to map deformation phenomena affecting urban areas by exploiting multitemporal sar data acquired by the new x band sensors with respect to those of the previous c band systems in particular we perform a comparative analysis of the deformation time series retrieved by applying the full resolution small baseline subset dinsar technique to selected sequences of sar data acquired by the envisat and radarsat 1 sensors both operating at c band and by the x band radar systems onboard the sar sensors of the cosmo skymed csk constellation this study focused on the city of napoli italy allows us to quantify the dramatic increase of the dinsar coherent pixel density achieved by exploiting the high resolution x band csk sar images a few meters resulting in an improvement factor of about 320 and 550 with respect to the radarsat 1 and envisat products respectively this improvement permits us to analyze nearly all the structures located within the investigated urbanized area and in many cases also portions of the same building the improved coherent pixel spatial densities combined with the reduced revisit times of the new x band sar missions allow us to significantly increase the effectiveness of the advanced dinsar methodologies further extending the role of those earth observation data in the development of monitoring scenarios

field monitoring of the corvara landslide dolomites italy and its relevance for hazard assessment the corvara landslide is an active slow moving rotational earth slide earth flow located uphill of the village of corvara in badia one of the main tourist centres in the alta badia valley in the dolomites province of bolzano italy present day movements of the corvara landslide cause national road 244 and other infrastructures to be damaged on a yearly basis the movements also give rise to more serious risk scenarios for some buildings located in front the toe of the landslide for these reasons the landslide has been under observation since 1997 with various field devices that enable slope movements to be monitored for hazard assessment purposes differential gps measurements on a network of 47 benchmarks has shown that horizontal movements at the surface of the landslide have ranged from a few centimetres to more than 1 m between september 2001 and september 2002 over the same period vertical movements ranged from a few centimetres to about 10 cm with the maximum displacement rate being recorded in the track zone and in the uppermost part of the accumulation lobe of the landslide borehole systems such as inclinometers and tdr cables have recorded similar rates of movement with the depths of the major active shear surfaces ranging from 48 m to about 10 m from these data it is estimated that the active component of the landslide has a volume of about 50 million m3 in this paper the monitoring data collected so far are presented and discussed in detail to prove that the hazard for the corvara landslide considered as the product of yearly probability of occurrence and magnitude of the phenomenon can be regarded has as medium or high if the velocity or alternatively the volume involved is considered finally it is also concluded that the monitoring results obtained provide a sound basis on which to develop and validate numerical models manage hazard and support the identification of viable passive and active mitigation measures

late holocene isotope hydrology of lake qinghai ne tibetan plateau effective moisture variability and atmospheric circulation changes a sub centennial resolution record of lacustrine carbonate oxygen isotopes 18oc from the closed basin lake qinghai on the ne tibetan plateau shows pronounced variability over the past 1500 years changes in 18oc in hydrologically closed lakes are often interpreted in terms of changing effective moisture under this interpretation our record would imply increasing effective moisture during the little ice age lia compared to the medieval warm period mwp however independent evidence from other archives strongly suggests the asian summer monsoon was stronger during the mwp and weakened during the lia controls other than effective moisture the balance of water inputs over evaporative loss must therefore have contributed to the 18oc values we propose the lia signal in lake qinghai resulted from a reduction in evaporation caused by colder air temperatures coupled with a decrease in oxygen isotope composition of input waters as a result of an increase in the relative importance of westerly derived precipitation our results caution against simplistic interpretations of carbonate oxygen isotope records from hydrologically closed lakes and suggest all possible controlling factors must be taken into account in order to avoid misleading palaeoclimatic reconstructions

the use of surface monitoring data for the interpretation of landslide movement patterns the tessina landslide is a large seasonally active slope failure located on the southern slopes of mt teverone in the alpago valley of ne italy consisting of a complex system that has developed in tertiary flysch deposits the landslide which first became active in 1960 threatens two villages and is hence subject to detailed monitoring with high quality data being collected using piezometers inclinometers extensometers and through the use of a highly innovative automated electronic distance measurement edm system which surveys the location of a large number of reflector targets once every 6 h these systems form the basis of a warning system that protects the villages but they also provide a very valuable insight into the patterns of movement of the landslide in this paper analysis is presented of the movement of the landslide concentrating on the edm dataset which provides a remarkable record of surface displacement patterns it is proposed that four distinct movement patterns can be established which correspond closely to independently defined morphological assessments of the landslide complex any given block of material transitions through the four phases of movement as it progresses down the landslide with the style of movement being controlled primarily by the groundwater conditions the analysis is augmented with modelling of the landslide undertaken using the itasca flac code the modelling suggests that different landslide patterns are observed for different parts of the landslide primarily as a result of variations in the groundwater conditions the model suggests that when a movement event occurs displacements occur initially at the toe of the landslide then retrogress upslope

the influence of 14c reservoir age on interpretation of paleolimnological records from the tibetan plateau there is a great deal of controversy regarding the fate of glaciers and ice fields on the tibetan plateau in the face of continued anthropogenic global warming paleoclimate reconstructions and spatial analyses aimed at mapping past climate changes are the key to understanding the climatic response of the tibetan plateau to changing conditions specifically the numerous lakes distributed across the tibetan plateau can provide high resolution spatial and temporal climate reconstructions to investigate past changes in the climate system in this paper we review the primary limitation to exploiting these valuable paleoclimate archives errors in radiocarbon based age models we review the techniques that have been used to estimate 14 c reservoir ages on the tibetan plateau and compile the published 14 c reservoir ages to examine their spatial and temporal patterns and to assess the imposed chronological uncertainties using site specific evaluations of bangong co and lake qinghai we demonstrate that 14 c age model uncertainties permit equally probable and contrasting interpretations of existing paleoclimate records we also examine 14 c induced uncertainties in the spatial climatic response on the tibetan plateau to 1 the termination of the last glacial maximum and 2 the holocene thermal maximum we conclude with recommendations for reducing uncertainties in future lake based paleoclimate studies on the tibetan plateau

monitoring of the large slow kahrod landslide in alborz mountain range iran by gps and sar interferometry in this study we quantify and analyze the spatial and temporal evolution of the surface displacement of kahrod landslide located in the center of alborz range iran within the haraz valley this landslide represents a threat for this main drainage axis and its numerous infrastructures we present three sets of displacement vectors based on gps technique an 8 benchmark network has been surveyed four times on a 1 year period basis it provides accurate information on the rate of displacement within the landslide and addresses the problem of the mechanical resistance of a small hillock down slope under the stress imposed by the landslide then this network is densified 57 marks and measured twice in 6 months using a rapidstatic approach this yields to a dense description of surface deformation over the whole landslide finally a 1 year time series of permanent gps recordings is presented and compared to rainfall furthermore we analyze envisat radar differential interferograms dinsar spanning the same period as permanent gps these geodetic data allow to precisely determine the limits of the current sliding zone and to describe the spatial and temporal evolution of surface displacement the combination of geodesy and field observations leads to a precise description of the past and present kinematics behavior of kahrod landslide the chaotic nature of the sliding mass suggests a first catastrophic landslide in a first episode during the period of observation the landslide appears to deform quite steadily and the evidence of short term correlation between rainfall and deformation amplitude needs to be confirmed by future measurements carrying on the acquisition of gps and insar data within the sliding mass but also within adjacent bedrock should give fundamental information with regards to major activation processes river sapping water seeping earthquakes or failure within the frontal hill of bedrock and their potential consequences

deflation of mount etna monitored by spaceborne radar interferometry ground based measurements of volcano deformation can be used to assess eruptive hazard but require the costly and often hazardous installation and maintenance of an instrument network here we show that spaceborne radar interferometry which has already shown its utility in mapping earthquake related deformation1 can be used to monitor long term volcano deformation two families of synthetic aperture radar images acquired from ascending and descending orbits by the satellite ers 1 and looking at mount etna from opposite sides cover the time period from 17 may 1992 to 24 october 1993 and include the second half of etna s most recent eruption despite artefacts of the interferometric technique we can observe a volcano wide deflation which is an expected consequence of the eruption but which had not previously been appreciated we quantify it using a simple model based on the change of pressure in a sphere located in an elastic half space the modelled deformation increases linearly with time until the end of the eruption our results show that it will be possible to use this technique to detect the inflation of volcanic edifices that usually precedes eruptions

climatic and topographic controls on the style and timing of late quaternary glaciation throughout tibet and the himalaya defined by 10be cosmogenic radionuclide surface exposure dating abstract temporal and spatial changes in glacier cover throughout the late quaternary in tibet and the bordering mountains are poorly defined because of the inaccessibility and vastness of the region and the lack of numerical dating to help reconstruct the timing and extent of glaciation throughout tibet and the bordering mountains we use geomorphic mapping and 10 be cosmogenic radionuclide crn surface dating in study areas in southeastern gonga shan southern karola pass and central western nyainqentanggulha shan and tanggula shan tibet and we compare these with recently determined numerical chronologies in other parts of the plateau and its borderlands each of the study regions receives its precipitation mainly during the south asian summer monsoon when it falls as snow at high altitudes gonga shan receives the most precipitation 2000 mm a 1 while near the margins of monsoon influence the karola pass receives moderate amounts of precipitation 500 600 mm a 1 and in the interior of the plateau little precipitation falls on the western nyainqentanggulha shan 300 mm a 1 and the tanggula shan 400 700 mm a 1 the higher precipitation values for the tanggula shan are due to strong orographic effects in each region at least three sets of moraines and associated landforms are preserved providing evidence for multiple glaciations the 10 be crn surface exposure dating shows that the formation of moraines in gonga shan occurred during the early mid holocene neoglacial and little ice age on the karola pass during the lateglacial early holocene and neoglacial in the nyainqentanggulha shan date during the early part of the last glacial cycle global last glacial maximum and lateglacial and on the tanggula shan during the penultimate glacial cycle and the early part of the last glacial cycle the oldest moraine succession in each of these regions varies from the early holocene gonga shan lateglacial karola pass early last glacial western nyainqentanggulha shan and penultimate glacial cycle tanggula shan we believe that the regional patterns and timing of glaciation reflect temporal and spatial variability in the south asian monsoon and in particular in regional precipitation gradients in zones of greater aridity the extent of glaciation has become increasingly restricted throughout the late quaternary leading to the preservation of old 100 ka glacial landforms in contrast in regions that are very strongly influenced by the monsoon 1600 mm a 1 the preservation potential of pre lateglacial moraine successions is generally extremely poor this is possibly because lateglacial and holocene glacial advances may have been more extensive than early glaciations and hence may have destroyed any landform or sedimentary evidence of earlier glaciations furthermore the intense denudation mainly by fluvial and mass movement processes which characterize these wetter environments results in rapid erosion and re sedimentation of glacial and associated landforms which also contributes to their poor preservation potential

differences between east asian and indian monsoon climate records during mis3 attributed to differences in their driving mechanisms evidence from the loess record in the sichuan basin southwestern china and other continental and marine climate records abstract asian monsoons vary with global climatic change as is well recorded by chinese loess paleosol sequences a radiocarbon and osl dated grain size and magnetic susceptibility record of the loess paleosol sequence from the chengdu basin southwestern china contains a greatly amplified mis 3 indian monsoon climate record comparison of this record with other continental and marine climate records in the temporal and frequency domains indicates that the high amplitude mis3 feature dominates the indian monsoon region and weakens northward but is not observed in east asian monsoon climate records these observed differences in the amplitude of mis 3 climate variations between the two monsoonal regions may be caused by the different effects of the precession insolation forcing on the very different monsoonal driving mechanisms the indian monsoon which originates from the subtropical mascarene high in the southern hemisphere carries large precession signals from the equatorial and tropic zones leading to the overall intensification of mis 3 climate signals the northward decrease of the indian monsoon strength reduces precessional climate signals carried by the monsoon on the other hand the east asian monsoon is largely generated from the western pacific subtropical high in the northern subtropical zone where the impact of precessional insolation forcing and heat vapor transport are much weaker thus exerting a more limited spatial and temporal influence on climate records

late cenozoic climate changes in china s western interior a review of research on lake qinghai and comparison with other records abstract we review late cenozoic climate and environment changes in the western interior of china with an emphasis on lacustrine records from lake qinghai widespread deposition of red clay in the marginal basins of the tibetan plateau indicates that the asian monsoon system was initially established by 8 ma when the plateau reached a threshold altitude subsequent strengthening of the winter monsoon along with the establishment of the northern hemisphere ice sheets reflects a long term trend of global cooling the few cores from the tibetan plateau that reach back a million years suggest that they record the mid pleistocene transition from glacial cycles dominated by 41 ka cycles to those dominated by 100 ka cycles during terminations i and ii strengthening of the summer monsoon in china s interior was delayed compared with sea level and insolation records and it did not reach the western tibetan plateau and the tarim basin lacustrine carbonate 18 o records reveal no climatic anomaly during mis3 so that high terraces interpreted as evidence for extremely high lake levels during mis3 remain an enigma following the last glacial maximum lsm several lines of evidence from lake qinghai and elsewhere point to an initial warming of regional climate about 14 500 cal yr bp which was followed by a brief cold reversal possibly corresponding to the younger dryas event in the north atlantic region maximum warming occurred about 10 000 cal yr bp accompanied by increased monsoon precipitation in the eastern tibetan plateau superimposed on this general pattern are small amplitude centennial scale oscillations during the holocene warmer than present climate conditions terminated about 4000 cal yr bp progressive lowering of the water level in lake qinghai during the last half century is mainly a result of negative precipitation evaporation balance within the context of global warming

a lateglacial and holocene lake record from the nianbaoyeze mountains and inferences of lake glacier and climate evolution on the eastern tibetan plateau abstract our 12 81 m long record from lake ximencuo provides insight into the lateglacial and holocene evolution of the lake and the nianbaoyeze glacier in its catchment and the regional climate history since 19 kyr lake ximencuo was a permanent deep lake throughout its history in contrast to numerous lakes on the tibetan plateau which experienced shallow lake levels or even desiccation during the lateglacial lake ximencuo was fed by large quantities of meltwater in the lateglacial the existence of glaciated upper catchment areas is apparently a prerequisite for lakes on the tibetan plateau which maintained relatively high water levels during the generally cold and dry periods following the global lgm 21 kyr a minor re advance of the nianbaoyeze glacier was recorded coeval with the greenland stadial 2a 16 4 and 14 5 kyr followed by rapid warming apparently synchronous with the greenland interstadial 1 warmest conditions were recorded at lake ximencuo during the early holocene which was punctured by a remarkable pulse of climate deterioration around 8 3 kyr this spell represents probably the 8 2 kyr event of the north atlantic region suggesting that it had a significant impact on the tibetan plateau colder conditions of longer duration occurred from 4 7 to 3 7 kyr apparently in phase with numerous records signalling colder and drier conditions on the tibetan plateau two minor spells of colder conditions and probably catchment erosion were recorded in the late holocene between 2 0 and 1 4 kyr and between 0 5 and 0 1 kyr with the latter representing the little ice age it is unclear whether human activities may have accelerated or even solely triggered the late holocene erosion events

enhanced landslide investigations through advanced dinsar techniques the ivancich case study assisi italy abstract we extensively exploit advanced differential sar interferometry dinsar techniques for enhanced landslide investigations we focus on the ivancich area assisi central italy which is affected by a deep seated landslide investigated through in situ surveys for this area large data sets of sar acquisitions were collected by the c band ers 1 2 and envisat sensors from april 1992 to november 2010 and by the x band radars of the cosmo skymed csk constellation from december 2009 to february 2012 we concentrate on the advanced dinsar technique referred to as small baseline subset sbas approach benefiting of its capability to generate deformation time series at full spatial resolution and from multi sensor sar data this allows us to present one of the first examples for a landslide area of ers 1 2 envisat deformation time series exceeding 18 years the results allowed characterizing the long term behaviour of the landslide and identifying sectors of the unstable slope affected by different deformation dynamics analysis of the csk data set characterized by a reduced revisit time and improved spatial resolution resulted in a 15 time larger point density with respect to the ers envisat measurements allowing to investigate nearly all the buildings and in many cases portions of buildings in the landslide area lastly we present an innovative modelling approach based on the effective integration of the dinsar measurements with traditional geological and geotechnical information providing deeper insights on the kinematical evolution of the landslide we consider our analysis a prototype example that can be extended to different geological and geotechnical conditions providing significant advances in the understanding of ground deformations induced by active landslides

wetland evolution in the qinghai lake area china in response to hydrodynamic and eolian processes during the past 1100 years abstract the daotanghe riverine wetland in close proximity to the qinghai lake was investigated to demonstrate the interrelationships between qinghai lake hydrodynamic processes eolian mobility and ecological conditions during the past 1100 years in response to climate change we used ostracod assemblages from various sites east of qinghai lake and from the sediment core qw15 of daotanghe pond and combined them with grain size and geochemical data from the same core the statistical extraction of grain size endmembers em revealed three different transportation processes responsible for pond related fluvio lacustrine pure fluvial and eolian deposits identified seasonal effects eolian mobility phase and timing of ice cover are possible tracers for the competing influence between the asian summer monsoon and the westerlies in the daotanghe wetland and surrounding area our results show that ostracod associations and sediment properties are evidence of a fluvio lacustrine fresh water environment without ingression of qinghai lake into the wetland hydrodynamic variations coupled with phases of eolian input indicate highly variable water budgets in response to climate induced effective moisture supply the medieval warm period mwp until about 1270 ce displays generally moist and warm climate conditions with minor fluctuations likely in response to variations in summer monsoon intensity the three partite period of the little ice age lia shows hydrologically unstable conditions between 1350 and 1530 ce with remarkably colder periods assigned to a prolonged seasonal ice cover pond desiccation and replacement by fluvial deposits occurred between 1530 and 1750 ce superimposed by eolian deposits the phase 1730 1900 ce is recorded by the re occurrence of a pond environment with reduced eolian input principal component analysis pca on ostracod abundances shows similar trends all three phases of the lia developed during a weak summer monsoon influence favoring westerly derived climate conditions until ca 1850 ce in accordance with records from the adjacent regions seasonal freezing periods in excess of the average time of frozen water bodies also occurred in periods of the well known grand solar minima and indicate stronger seasonality possibly independent from variations in summer monsoon strength but with links to global northern hemispheric climate

a tibetan lake sediment record of holocene indian summer monsoon variability article history sedimentological data and hydrogen isotopic measurements of leaf wax long chain n alkanes dwax from an alpine lake sediment archive on the southeastern tibetan plateau paru co provide a holocene perspective of indian summer monsoon ism activity the sedimentological data reflect variations in lake level and erosion related to local ism rainfall over the paru co catchment whereas dwax reflects integrated synoptic scale ism dynamics our results indicate that maximum ism rainfall occurred between 10 1 and 5 2 ka during which time there were five century scale high and low lake stands after 5 2 ka the ism trended toward drier conditions to the present with the exception of a pluvial event centered at 0 9 ka the paru co results share similarities with paleoclimate records from across the tibetan plateau suggesting millennial scale ism dynamics were expressed coherently these millennial variations largely track gradual decreases in orbital insolation the southward migration of the intertropical convergence zone itcz decreasing zonal pacific sea surface temperature sst gradients and cooling surface air temperatures on the tibetan plateau centennial ism and lake level variability at paru co closely track reconstructed surface air temperatures on the tibetan plateau but may also reflect indian ocean dipole events particularly during the early holocene when enso variability was attenuated variations in the latitude of the itcz during the early and late holocene also appear to have exerted an influence on centennial ism rainfall 2014 elsevier b v all rights reserved

deciphering the effect of climate change on landslide activity a review abstract increased landslide activity is commonly listed as an expected impact of human induced climate change this paper examines the theoretical and empirical bases for this assertion it identifies the mechanisms by which climate can induce landsliding and examines the manner in which these mechanisms may respond to changes in a range of climatic parameters it is argued that inherent limiting stability factors which vary with different terrain conditions and landslide types ultimately govern the nature of response to changing climate several modelling approaches are evaluated on the basis of their potential to predict landslide response to climate projections given reliable input data of appropriate form and resolution the existing slope stability hydrological and statistical models are for the most part capable of yielding useful prognoses on occurrence reactivation magnitude and frequency of landsliding while there is a strong theoretical basis for increased landslide activity as a result of predicted climate change there remains a high level of uncertainty resulting from the margins of error inherent in scenario driven global climate predictions and the lack of sufficient spatial resolution of currently available downscaled projections examples from new zealand are used to illustrate the extent to which changes resulting from human activity have affected slope stability changes resulting from human activity are seen as a factor of equal if not greater importance than climate change in affecting the temporal and spatial occurrence of landslides

base liquefaction a mechanism for shear induced failure of loose granular slopes for the deviatoric strain softening associated with static liquefaction to occur in a landslide the soil must be contractile be subjected to a monotonic loading trigger and be sufficiently satur

soil deformation measurement using particle image velocimetry piv and photogrammetry a deformation measurement system based on particle image velocimetry piv and close range photogrammetry has been developed for use in geotechnical testing in this paper the theory underlying this system is described and the performance is validated digital photography is used to capture images of planar soil deformation using piv the movement of a fine mesh of soil patches is measured to a high precision since piv operates on the image texture intrusive target markers need not be installed in the observed soil the resulting displacement vectors are converted from image space to object space using a photogrammetric transformation a series of validation experiments are reported these demonstrate that the precision accuracy and resolution of the system are an order of magnitude higher than previous image based deformation methods and are comparable to local instrumentation used in element testing this performance is achieved concurrent with an order of magnitude increase in the number of meas

late quaternary water depth changes in hala lake northeastern tibetan plateau derived from ostracod assemblages and sediment properties in multiple sediment records abstract late pleistocene and holocene climate dynamics along the marginal belt of the east asian summer monsoon in china and their responses to hydrological cycles in lake basins of the tibetan plateau are still a matter of scientific discussion hala lake a closed 65 m deep lake basin in the western qilian mountains qinghai province is considered a monitor of climate driven hydrological and environmental changes during the past 24 kyr bp the distribution patterns of ostracod assemblages stable isotopes sediment geochemical properties in four sediment records from different water depths and their combination with the unique limnological setting enabled us to reconstruct four major phases of centennial scale water depth fluctuations from the global last glacial maximum ca 24 kyr bp to the present our results show that hala lake experienced a very shallow and small water body during the lgm and lateglacial under cold and dry climate conditions rapid increase of water depth and contemporaneous lake expansion started at around 14 kyr bp phase i most likely as a result of glacier melt due to the onset of climate warming the lake reached 45 m water depth at around 13 5 kyr bp reduced water depth during the younger dryas spell ca 12 kyr bp may be attributed to a short term return to cooler and drier conditions during the early holocene phase ii water depth increased further toward lake highstands close to its present level with a highest lake level of up to 9 m above the present lakestand at 8 0 7 8 kyr bp besides continued glacier melt supply we assume that summer monsoon effective moisture contributed to the overall water budget but remained relatively unstable favoring water depth fluctuations a pronounced lower water depth falls into the period between 9 2 and 8 1 kyr bp perhaps the result of weak monsoon influence or its complete absence although the warming trend continued toward its optimum at ca 8 7 kyr bp a distinct mass flow most likely triggered by an earthquake occurred during a lake lowstand either at ca 7 0 kyr bp or at around 8 1 kyr bp the mid holocene phase iii was characterized by fluctuating water depths between 7 8 and 4 5 kyr bp conflicting trends of stable isotope data limit the validity of water depth estimations but may show higher lake levels between 5 5 and 4 5 kyr bp coincident with dated lake sediments in a cliff position at the northern lake shore this positive water balance can most likely be attributed to increased westerly derived moisture supply during autumn and late winter although summer monsoon influence could also be of significance coincident with the 4 2 ka event the lake experienced shallow water at around 4 1 kyr bp perhaps as a result of continued cooling and drier climate conditions supporting the arguments of a general cooling trend throughout the holocene the late holocene phase iv is characterized by extremely unstable hydrological conditions with rapid fluctuations in water depth more frequently controlled by westerly driven effective moisture supply since the lake lowstand at about 1 4 1 2 kyr bp the lake has developed toward its present level our research underlines the necessity for comparing multiple proxy records from different lake sites to better evaluate centennial scale climate driven variations throughout the late pleistocene and holocene periods all presented data suggest the variable influence of summer monsoon effective moisture on the hydrological budget of the lake water depth variations did not follow the long term pattern of the asian monsoon system due to a potential modulation by westerly derived moisture impact

analysis of ground deformation detected using the sbas dinsar technique in umbria central italy ground deformation affecting the umbria region central italy in the 9 year period from 1992 to 2000 was investigated through multi temporal differential synthetic aperture radar interferometry dinsar for the purpose the small baseline subset sbas technique was adopted which allows studying the temporal evolution of the detected deformation at two spatial scales a low resolution regional scale and a full resolution local scale for the analysis sar data acquired by the european remote sensing ers 1 2 satellites along ascending and descending orbits were used the detected deformation was analysed to investigate its relevance to geophysical geomorphologic and human induced processes that may result in hazardous conditions to the population of umbria low resolution deformation data were used to i determine the amount of displacement caused by the umbria marche earthquake sequence from september 1997 to april 1998 in the foligno area ii determine the number and percentage of the known landslides that can be monitored by the dinsar technology in the investigated area and iii identify and measure subsidence induced by exploitation of a confined aquifer in the valle umbra results indicate that earthquakes moved through the foligno area westwards up to 3 9 cm and with an uplift reaching 1 7 cm intersection in a gis of the low resolution deformation maps with a detailed landslide inventory map allowed the determination that the portion of landslides that can be monitored by the sbas dinsar technique in umbria ranges from 2 7 to 3 4 and the percentage of the total landslide area ranges from 10 4 to 12 8 in the valle umbra a dependency was found between the time and the amount of detected ground deformation and the record of water withdrawal the full resolution deformation data were used to investigate the movement of the ivancich landslide in the assisi municipality joint analysis of the spatial and the temporal characteristics of the ground displacement allowed the formulation of a hypothesis on the landslide geometry and deformation pattern

landslide inventory maps new tools for an old problem landslides are present in all continents and play an important role in the evolution of landscapes they also represent a serious hazard in many areas of the world despite their importance we estimate that landslide maps cover less than 1 of the slopes in the landmasses and systematic information on the type abundance and distribution of landslides is lacking preparing landslide maps is important to document the extent of landslide phenomena in a region to investigate the distribution types pattern recurrence and statistics of slope failures to determine landslide susceptibility hazard vulnerability and risk and to study the evolution of landscapes dominated by mass wasting processes conventional methods for the production of landslide maps rely chiefly on the visual interpretation of stereoscopic aerial photography aided by field surveys these methods are time consuming and resource intensive new and emerging techniques based on satellite airborne and terrestrial remote sensing technologies promise to facilitate the production of landslide maps reducing the time and resources required for their compilation and systematic update in this work we first outline the principles for landslide mapping and we review the conventional methods for the preparation of landslide maps including geomorphological event seasonal and multi temporal inventories next we examine recent and new technologies for landslide mapping considering i the exploitation of very high resolution digital elevation models to analyze surface morphology ii the visual interpretation and semi automatic analysis of different types of satellite images including panchromatic multispectral and synthetic aperture radar images and iii tools that facilitate landslide field mapping next we discuss the advantages and the limitations of the new remote sensing data and technology for the production of geomorphological event seasonal and multi temporal inventory maps we conclude by arguing that the new tools will help to improve the quality of landslide maps with positive effects on all derivative products and analyses including erosion studies and landscape modeling susceptibility and hazard assessments and risk evaluations

morphological and kinematic evolution of a large earthflow the montaguto landslide southern italy article ml ong earthflow in the southern apennines of italy following an analysis of th ed ifferent methods and techniques available to measure surface modifications caused by a large earthflow we selected a combination of monitoring techniques com patible with the montaguto case study we exploited i visual interpretation of aerial and satellite imagery ii quantitative analysis of six digital elevation model s dems covering the landslide area and iii al arge set of high accuracy three dimensional topographic measurements captured by three robotised total stations rtss in tegration of the results obtained from the different monitoring techniques allowed us to investigate the long multi decadal and short seasonal term evolution of the montaguto earthflow in the 58 year period 1954 2011 the examination of the available aerial satellit ea nd hill shade images revealed ac yclic long term behaviour of mass movements of different types in the rio nocelle catchment occupied by the recent montaguto earthflow the combined analysis of the six dems allowed measuring the material eroded from the landslide crown area v 1 4 10 6

a high resolution monsoon record of millennial scale oscillations during late mis 3 from wulu cave south west china a speleothem record from south western china characterizes in detail the millennial scale changes in asian monsoon am intensity from 39 3 to 28 7 ka the calcite 18o profile with an average resolution of 8 years shows several strong monsoon events concurrent with greenland interstadials gis 8 4 to gain a systematic perspective of am millennial scale variability the new and previously reported data from the same cave are combined showing that am variation exhibits a broad similarity with greenland ice 18o records and with antarctica but in an opposite sense for the interval that encompasses gis 5 and gis 4 1 however our stalagmite 18o record depicts a sustained strong monsoon with no distinctive oscillation between these interstadials another prominent characteristic in our record is a gradual transition into chinese interstadial cis 8 which is well constrained by an annually laminated sequence we find that an initial rise in monsoon intensity lasting a few centuries significantly precedes the abrupt onset of cis 8 in the am realm this suggests that atmospheric moisture and heat transport are probably capable of inducing abrupt climate change when a rapid reorganization of ocean atmosphere circulations passes a tipping point

erosion and exhumation in the himalaya from cosmogenic isotope inventories of river sediments the outward erosional flux is a key factor in the tectonic evolution of mountain belts and there is much debate about the feedbacks between tectonics erosion and climate here we use cosmogenic nuclides 10be and 26al analysed in quartz from river sediments from the upper ganges catchment to make the first direct measurements of large scale erosion rates in a rapidly uplifting mountain belt the erosion rates are highest in the high himalaya at 2 7 0 3 mm yr 1 errors fall to 1 2 0 1 mm yr on the southern edge of the tibetan plateau and are 0 8 0 3 to 0 6 mm yr in the foothills to the south of the high mountains these relative estimates are corroborated by the nd isotopic mass balance of the river sediment analysis of sediment from an abandoned terrace suggests that similar erosion rates have been maintained for at least the last few thousand years the data presented here along with data recently published for european river catchments demonstrate that a log linear relationship between relief and erosion rate holds over three orders of magnitude variation in erosion rate and between very different climatic and tectonic regimes the erosion rate estimates from cosmogenic nuclides correlate well with exhumation rates calculated from previously published apatite fission track ages in the indian himalaya this confirms that much of the exhumation in the himalayan mountain chain is now balanced by erosion however exhumation rates calculated from high blocking temperature systems such as 40ar 39ar in muscovite imply lower exhumation rates rocks presently at the surface must have undergone a three to six fold increase in exhumation rate within the last few million years we show how this could be explained either by climatic forcing of erosion rate changes or by tectonics published evidence for equally rapid changes of exhumation rate in the past and the probable diachroneity in the time at which the present exhumation rates accelerated imply that tectonics has moderated at least some of the change in exhumation rates

hydrological evolution during the last 15 kyr in the tso kar lake basin ladakh india derived from geomorphological sedimentological and palynological records abstract the tso kar lake basin in ladakh northwestern himalayas 33 18 n 78 e 4527 m a s l is located close to the modern boundary of effective moisture transport from the indian summer monsoon in order to reconstruct the possible monsoonal impact on the hydrology of the lake basin during the last 15 kyr we studied the geomorphology of the basin and combined the results with multi proxy records from tso kar lake sediments major analyses comprise geochemical data high resolution x ray fluorescence xrf mineral composition xrd aquatic pollen and non pollen palynomorphs npp although the chronological framework based on 41 14c ams dates remains speculative for the lateglacial and late holocene periods our results indicate major hydrological phases linked to regional climate variations and tectonic activity the maximum glacier advance falls within the period between the global lgm and ca 15 kyr bp while the basin remained open and may have drained along the paleo tso kar river tectonic pulses may have triggered terrace development and the closure of the lake the estimated mean vertical displacement rate accounts for 7 9 mm yr considerable summer monsoon moisture supply occurred for the periods around 12 5 kyr bp and between ca 11 5 and 8 6 kyr bp indicated by deposition of more profundal lake facies and the development of aquatic fauna and flora the lake level rise about 11 8 kyr bp was due to intensified glacier melt and summer monsoon effective moisture supply the lake reached its maximum level and extent between 8 5 and 7 kyr bp under warm moist climate conditions permafrost was absent from the basin summer monsoon influence weakened after 8 kyr bp with a short reverse trend at ca 5 6 kyr bp the lake shrank gradually after 7 kyr bp towards its lowest stand at about 4 2 kyr bp with return of permafrost activity subsequent terrace formation was probably amplified by tectonic movement the lake remained at a low level with minor fluctuations the results indicate that the orbitally driven regional climate variability is well reflected in the tso kar basin by hydrological variations considerable summer monsoon moisture seems to have influenced the area only during the early holocene the late quaternary evolution of the tso kar was controlled by the interplay of climate forces local morphodynamics and tectonic impact

constraining holocene lake level highstands on the tibetan plateau by 10be exposure dating a case study at tangra yumco southern tibet abstract many lakes on the tibetan plateau are surrounded by palaeo shorelines that document former lake level highstands and hence past changes in climate establishing accurate chronologies for these shorelines is crucial to correlate lake level fluctuations with palaeo environmental histories that are commonly inferred from lake sedimentary records here we apply surface exposure dating to constrain the age of two lake level highstands at one of the largest tibetan lakes tangra yumco which has well developed palaeo shorelines located up to 185 m above the current lake for sampling we focussed on wave cut bedrock terraces that vary considerably in width because they were carved into rocks of different erodibility samples from the highest strath terrace 180 185 m above the lake at three different sites yield tightly clustered 10 be ages between 7 39 0 19 ka and 7 87 0 27 ka internal errors which constrain the end of an early holocene lake level highstand at 7 6 0 6 ka external error the consistency of the 10 be ages indicates that bedrock erosion by wave attack reduced the inherited 10 be component to negligible amounts because otherwise samples would show considerable age scatter two bedrock samples from a lower terrace 140 145 m above the lake and one amalgamated clast sample from a beach ridge on the same terrace yield 10 be ages between 4 04 0 14 ka and 4 50 0 15 ka these ages document that the lake level dropped by 40 m between 7 6 ka and 4 3 ka granite boulders from the two investigated terraces yield apparent 10 be ages that are 6 ka and 27 ka older than the ages of the respective terraces indicating that this sample type is not reliable in this setting overall our results demonstrate that exposure dating of bedrock terraces provides a valuable tool to reconstruct lake level histories on the tibetan plateau

holocene itcz and indian monsoon dynamics recorded in stalagmites from oman and yemen socotra abstract high resolution oxygen isotope 18o profiles of holocene stalagmites from four caves in northern and southern oman and yemen socotra provide detailed information on fluctuations in precipitation along a latitudinal transect from 12 n to 23 n 18o values reflect the amount of precipitation which is primarily controlled by the mean latitudinal position of the itcz and dynamics of the indian summer monsoon ism during the early holocene rapidly decreasing 18o values indicate a rapid northward displacement in the mean latitudinal position of the summer itcz and the associated ism rainfall belt with decadal to centennial scale changes in monsoon precipitation correlating well with high latitude temperature variations recorded in greenland ice cores during the middle to late holocene the summer itcz continuously migrated southward and monsoon precipitation decreased gradually in response to decreasing solar insolation a trend which is also recorded in other monsoon records from the indian and east asian monsoon domains importantly there is no evidence for an abrupt middle holocene weakening in monsoon precipitation although abrupt monsoon events are apparent in all monsoon records they are short lived and clearly superimposed on the long term trend of decreasing monsoon precipitation for the late holocene there is an anti correlation between ism precipitation in oman and inter monsoon spring autumn precipitation on socotra revealing a possible long term change in the duration of the summer monsoon season since at least 4 5 ka bp together with the progressive shortening of the ism season gradual southward retreat of the mean summer itcz and weakening of the ism the total amount of precipitation decreased in those areas located at the northern fringe of the indian and asian monsoon domains but increased in areas closer to the equator

basin morphology and seismic stratigraphy of lake donggi cona north eastern tibetan plateau china basin morphology and depositional stratigraphy of lake donggi cona on the north eastern tibetan plateau has been studied with echo depth sounding and shallow seismic sub bottom profiling the basin is a pull apart structure situated at the highly active kunlun fault it is characterised by a 92 m deep graben structure in the western part of the lake basin and a shallow eastern lake part the latter filled up with fluvial sediments from a large alluvial plain three prominent morphological levels were identified at 24 m 39 m and 57 m below present lake level they were partly created by basin subsidence while the deposition of prograding delta sediments primarily formed the morphological steps the inherited tectonic structures control on going neotectonic activity which seems to have only minor influence on present basin morphology the basin is filled by sediments of at least 30 m thickness in the depocentre three major depositional units can be distinguished in comparison with lithological changes in a sediment core they give evidence of pronounced lake level fluctuations and dramatic changes in lake volume a numerical age datum of w19 cal ka bp at the base of the sediment core allows a tentative reconstruction of late glacial to holocene lake development a very low base level preceded a time of delta formation during higher lake level i e w26 m lower than present during last glacial maximum creating a lake of only 18 of its present size at the transition to holocene the lake level rose very quickly changing to a deep lake environment thus transgression may have promoted maximum lake stands

surface displacements associated with the l aquila 2009 mw 6 3 earthquake central italy new evidence from sbas dinsar time series analysis 1 we investigate the surface displacements in the area affected by the april 2009 l aquila earthquake central italy through an advanced dinsar analysis in particular we apply the sbas approach to retrieve deformation maps and displacement time series from envisat data acquired between february 2003 and october 2009 and from cosmo skymed data relevant to the six month interval following the earthquake our analysis shows no evidence of pre seismic surface deformation at the 35 day temporal sampling of the envisat sensor on the other hand by benefiting of the high spatial resolution and temporal sampling of the cosmo skymed satellites we measure post seismic displacements at an unprecedented level of detail for a dinsar analysis this allows us to identify three main areas continuing to deform after the earthquake in addition our modeling shows that post seismic displacements are very likely related to the fault afterslip since their decay times are on the order of 101 102 days

a regional record of expanded holocene wetlands and prehistoric human occupation from paleowetland deposits of the western yarlung tsangpo valley southern tibetan plateau abstract the asian monsoon which brings 80 of annual precipitation to much of the tibetan plateau provides runoff to major rivers across the asian continent paleoclimate records indicate summer insolation and north atlantic paleotemperature changes forced variations in monsoon rainfall through the holocene resulting in hydrologic and ecologic changes in plateau watersheds we present a record of holocene hydrologic variability in the yarlung tsangpo yt valley of the southern tibetan plateau based on sedimentology and 14 c dating of organic rich black mats in paleowetlands deposits that shows changes in wetlands extent in response to changing monsoon intensity four sedimentary units indicate decreasing monsoon intensity since 10 4 ka bp wet conditions occurred at 10 4 ka bp 9 6 ka bp and 7 9 4 8 ka bp with similar to modern conditions from 4 6 2 0 ka bp and drier than modern conditions from 2 0 ka bp to present wetland changes correlate with monsoon intensity changes identified in nearby records with weak monsoon intervals corresponding to desiccation and erosion of wetlands dating of in situ ceramic and microlithic artifacts within the wetlands indicates epipaleolithic human occupation of the yt valley after 6 6 ka bp supporting evidence for widespread colonization of the tibetan plateau in the early and mid holocene during warm wet post glacial conditions

multiple seepage faces on layered slopes and their implications for slope stability analysis this study provides an analysis of the water table configuration and pore pressure distribution in layered hillsides a finite element model was used to simulate two dimensional saturated unsaturated steady state flow through layered slopes a laboratory sand tank experiment was used to verify the physical foundation of the mathematical model it is shown that layered slopes feature multiple seepage faces perched water tables and wedge shaped unsaturated zones the pore pressure distribution and the distribution of multiple seepage faces are strongly dependent on the position of the impeding layers and their hydraulic properties predictions of pore pressure fields based on homogeneous saturated analyses may be significantly in error when applied to problems on layered slopes slope stability analyses on layered slopes that do not take into account the presence of unsaturated wedges beneath the impeding layers can lead to overdesign of the stable slope angle key words groundwater conditions unsatu

late quaternary hydrological changes inferred from lake level fluctuations of nam co tibetan plateau china abstract this paper discusses the range of lake level changes using hydro acoustic techniques and sediment core data for lake nam co in central tibet china this second largest tibetan lake is situated at an elevation of 4718 m a s l lake level changes with different high stands documented by beach remnants are widespread on the tibetan plateau and also in lake nam co they indicate significant changes in the hydrological system triggered by the monsoonal circulation using hydro acoustic techniques submerged beach remains at approximately 10 15 m 30 m 45 m 70 m and 95 m below present day lake level were detected indicating a more negative water balance than today the 10 15 m lake level is dated to an age equal to the little ice age all deeper lake levels are assumed to have been formed prior to 10000 cal bp folded older sediments detected in the hydro acoustic profiles indicate a possible larger extent of the glaciers during or prior to the last glacial maximum lgm this is followed by a low stand or even by possible desiccation of the entire lake basin during or after the lgm

north south extension in the tibetan crust triggered by granite emplacement we combine zircon sensitive high resolution ion microprobe u pb spot dating and mica 4 0 ar 3 9 ar plateau ages with field geological and geochemical constraints from the malashan area of southern tibet to show that the deformed granite core of the north himalayan metamorphic domes in this area is not indian basement but was intruded and deformed during the himalayan orogeny microstructural observations reveal that a transition from top to the south thrust related to top to the north extension related deformation occurred during granite intrusion and related metamorphism this suggests that intrusion triggered the onset of extensional tectonics in the tibetan middle to upper crust expected positive feedback mechanisms between decompression melting leading to more intrusion and more extensional deformation suggest that this mechanism may have been important on a regional scale

probabilistic landslide hazard assessment at the basin scale abstract we propose a probabilistic model to determine landslide hazard at the basin scale the model predicts where landslides will occur how frequently they will occur and how large they will be we test the model in the staffora river basin in the northern apennines italy for the study area we prepare a multi temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999 we partition the basin into 2243 geo morpho hydrological units and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables including morphological lithological structural and land use for each mapping unit we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period assuming that landslide recurrence will remain the same in the future and adopting a poisson probability model we determine the exceedance probability of having one or more landslides in each mapping unit for different periods we obtain the probability of landslide size by analysing the frequency area statistics of landslides obtained from the multi temporal inventory map assuming independence we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size of landslide temporal occurrence and of landslide spatial occurrence

geomorphic and chronometric evidence for high lake level history in gahai lake and toson lake of north eastern qaidam basin north eastern qinghai tibetan plateau palaeoshorelines highstand lacustrine sediments and lakeshore terraces are preserved around saline lakes in the arid qaidam basin previous research indicates that the chronology of a mega paleolake in the qaidam basin during the late pleisotocene is controversial here we report quartz optically stimulated luminescence osl age estimates of highstand lacustrine sediments shoreline features and geomorphic exposures that contribute to a revision of the lake level history of gahai and toson lakes in the north eastern qaidam basin on the northeastern qinghai tibetan plateau qtp margin the results imply that i high lake levels at gahai and toson lakes based on quartz osl dating occurred at 85 72 63 55 31 5 4 and 0 9 0 7 ka probably corresponding to periods of warm and wet climate ii periods of high lake levels are almost synchronous with other lakes on the qtp e g qinghai and namco lakes with the highest late pleistocene levels occurring during marine oxygen isotope stage 5 and iii highstand phases on the qtp are out of phase with those of low latitude lakes in the southern hemisphere possibly driven by solar insolation variability in the low latitude region copyright 2011 john wiley sons ltd

hydrological variations on the central tibetan plateau since the last glacial maximum and their teleconnection to inter regional and hemispheric climate variations decadal to sub decadal variability of inflow evaporation and biological productivity derived from lake nam co was used to reconstruct hydrological changes for the past ca 24 k cal a bp the timing of these variations corresponds to known climatic shifts on the northern hemisphere after a dry and cold last glacial maximum the lake level of nam co initially rose at ca 20 k cal a bp moist but further cold conditions between ca 16 2 and 14 k cal a bp correspond to heinrich event 1 a warm and moist phase between ca 14 and 13 k cal a bp is expressed as a massive enhancement in inflow and biological productivity and might be associated with a first intensification of the indian ocean summer monsoon coinciding with the bolling allerod complex a two step decrease in inflow and a contemporaneous decline in biological productivity until ca 11 8 k cal a bp points to cool and dry conditions during the younger dryas lake levels peak at ca 9 4 k cal a bp although hydrological conditions remain relatively stable during the holocene with only low amplitude variations observed

climate change vegetation history and landscape responses on the tibetan plateau during the holocene a comprehensive review abstract numerous studies of changes in the climate vegetation and landscape responses of the tibetan plateau tp during the holocene have been published in recent decades however several conflicting interpretations are evident within these studies and a comprehensive review of the topic is needed to reconcile them and thus to provide an improved understanding of the history and forcing mechanisms of holocene environmental changes within the region here we review the evidence for changes in climate temperature precipitation moisture vegetation and landscape attributes glacier and eolian activity on the tp during the holocene our main conclusions are as follows 1 the patterns of holocene mean annual temperature change on the tp remain controversial however an early to middle holocene summer temperature maximum is evident which coincided with high summer insolation and a strengthening of the indian summer monsoon ism this suggests that the summer land sea thermal gradient impacted by the temperature of the tp may be an important factor driving orbital scale ism changes 2 lake level records indicate an optimum in moisture conditions on the southwestern sw tp in the early holocene while on the northeastern ne tp the optimum occurred in the middle to late holocene this out of phase or anti phased relationship may be linked to the role of the ism in dominating precipitation on the sw tp while the westerlies and east asian summer monsoon dominated the precipitation on the ne tp 3 most of the lake sediment based stable isotope records 18o and leaf wax d exhibit a pattern similar to that of stalagmite 18o records from monsoonal asia reflecting the dominance of large scale patterns of atmospheric circulation rather than localized moisture changes reflected by lake level records 4 a synthesis of pollen records reveals that the extent of forest was maximal in the mid holocene while from the early holocene onwards alpine steppe shrunk and alpine meadow and desert gradually expanded 5 evidence of glacier advance increased slightly during the early holocene decreased during the mid holocene and then increased substantially after 3 ka bp 6 the integrated ages of eolian sand and loess from the ne tp reveal that eolian activity intensified during the early and late holocene site inter comparisons reveal that regional climate change played a major role in modulating changes in vegetation and other landscape attributes overall producing holocene climate reconstructions for the entire tp remains a major challenge even though much progress has been made further improvements in terms of the spatial coverage of high resolution paleoclimatic records with robust chronological control and a deeper understanding of the specific climatic significance of several climatic proxies will facilitate an improved understanding of how the monsoon and the westerlies interacted and their impacts on vegetation and landscape changes on the tp

dynamics of slow moving landslides from permanent scatterer analysis high resolution interferometric synthetic aperture radar insar permanent scatterer data allow us to resolve the rates and variations in the rates of slow moving landslides satellite to ground distances range changes on landslides increase at rates of 5 to 7 millimeters per year indicating average downslope sliding velocities from 27 to 38 millimeters per year time series analysis shows that displacement occurs mainly during the high precipitation season during the 1997 1998 el nino event rates of range change increased to as much as 11 millimeters per year the observed nonlinear relationship of creep and precipitation rates suggests that increased pore fluid pressures within the shallow subsurface may initiate and accelerate these features changes in the slope of a hill resulting from increases in the pore pressure and lithostatic stress gradients may then lead to landslides

investigations into the relationship between changes in internal moisture regimes and rock surface deterioration in cavernous sandstone features cavernous features commonly develop in sandstone but their development over time remains enigmatic it has been suggested that moisture movements within the rock mass play a key role in the location development and dynamics of cavernous features in this research the role of internal moisture movement is tested through monitoring moisture and surface deterioration dynamics in april 2008 and april 2009 within two large cavernous features mega tafoni in the golden gate highlands national park south africa gghnp data are presented from surveys of internal moisture using electrical resistivity tomography ert surface moisture using a protimeter and deterioration using surface hardness as recorded with an equotip as a proxy for surface deterioration across five 2 45 m long transects in addition a high resolution temperature record is presented to assess the influence of micro climates within the caverns the results indicate consistency in the gross spatial pattern of moisture flow within the rock mass over a one year period but significant changes in mean moisture contents and in the fine detail of moisture patterning some noticeably weakened areas had developed within the central parts of the cavernous features often linked to wetter subsurface conditions supporting the theory that core softening is a main driver of cavernous feature formation however in some areas surface hardening is also found to be associated with wetter subsurface conditions supporting the theory that case hardening is a main driver of cavernous feature formation in addition the presence of well established biofilms suggests an even more complex interaction between moisture surface development and biological activity a model is presented therefore which integrates this paradox by proposing a non linear relationship between moisture dynamics facilitation of biofilm formation and deterioration within cavernous features

causative mechanisms of rainfall induced fill slope failures slope failures in fill slopes formed by loosely compacted completely decomposed granite in hong kong occur commonly during intense tropical rainstorms the stress path greatly influences the shear strength of the soil mass and is therefore crucial to the identification of slope failure mechanisms the soil mass in this case is largely unsaturated in situ hydrologic response to rainstorms indicates that soil suction is reduced by rainfall infiltration which often becomes the triggering factor in initiating slope instability the constant dead load tests on unsaturated loosely compacted completely decomposed granite appropriately simulate the field stress path of rainfall induced fill slope failure by reducing suction the tests indicate that matric suction contributes to the dilative or contractive behavior of the unsaturated soils the anisotropically consolidated undrained triaxial tests demonstrate the consistently contractive behavior of the specimens on this basis we delineate the in situ stress conditions leading to the initiation of rainfall induced fill slope failure and the stress paths of the transformation from local failures to flowage based on a systematic study of fill slope case records in hong kong implications of such mechanisms on fill slope stability are given

space geodesy subsidence and flooding in new orleans a subsidence map of the city offers insight into the failure of the levees during hurricane katrina

influence of stress ratio and stress path on behavior of loose decomposed granite this paper presents results from four series of triaxial compression tests of loosely compacted decomposed granite dg or silty sand on both isotropically and anisotropically consolidated specimen

on the effects of 3 d mechanical heterogeneities at campi flegrei caldera southern italy 1 campi flegrei caldera located near the highly populated city of naples southern italy is characterized by long term subsidence punctuated by fast uplift phases most of the interpretations of the ground deformation are still based on standard models that assume the lithosphere to behave as a homogeneous half space however several geophysical investigations show the presence of vertical and lateral heterogeneities especially in the shallow subsurface which might have an effect on the interpretation of the surface displacements our 3 d finite element models constrained by seismic tomography to take into account the realistic distribution of mechanical heterogeneities demonstrate that at campi flegrei the assessment of the source location is independent of the consideration of 3 d heterogeneities while the evaluation of its strength is overestimated thus we propose an approach that still allows use of standard homogeneous half space models but accounts for 3 d heterogeneity effects this procedure applied to the deformation field revealed by differential synthetic aperture radar interferometry dinsar over the past 16 years provides new insights for the understanding of the ground displacements observed at campi flegrei caldera this work provides an approach for a quantitative evaluation of the effects of mechanical heterogeneities on surface deformation analogous procedures can be also applied in other volcanic areas where similar to campi flegrei caldera a priori information on the mechanical heterogeneities distribution is available

sources and behavior of monsoon air masses in the lowest latitude region on the tibetan plateau and their paleoclimatic implications abstract to better understand the reported paleoclimate features and underlying mechanisms in the lowest latitude region 28 n to 29 30 n where 12 major river gorges cross the himalayas of the southern tibetan plateau we aim to elucidate the major sources and behavior of modern monsoon air masses in the region based on spatial variations in the 18o and 2h of stream water and precipitation and vegetation during the summer monsoon season our main findings were following the river gorges high mountain ranges bearing extensive dense vegetation and stronger solar insolation characteristic of the lowest latitude region may have functioned for an extended period as the essential geological settings for strongly drawing significant amounts of moisture from the indian ocean toward the region without passing through the yarlung zangbo basin the combination of such geological settings specific to this region may have caused its earlier response to the climate amelioration after a cold dry event such as the younger dryas and heinrich 1 compared to other regions on the plateau furthermore gorge derived monsoon air masses that blew through the lowest latitude region are highly likely to have more significantly influenced the onset of the climate amelioration after a cold dry event even in the southwestern south central and southeastern regions rather than the yarlung zangbo derived monsoon air masses therefore this caused the subsequent expansion of the indian summer monsoon ism over the plateau thus with its unique geological setting the lowest latitude region has presumably played a critical role as the key region i e the initiator for the early evolution of the ism on the tibetan plateau by responding to climate amelioration after cold dry events more rapidly than any other region and drawing gorge derived monsoon air masses strongly toward the region

instability caused by a seepage impediment in layered fill slopes the underlying cause of loose fill slope failures in hong kong has been attributed to static liquefaction during heavy rainfall a series of centrifuge model tests and numerical analyses were condu

a high resolution absolute dated holocene and deglacial asian monsoon record from dongge cave china abstract we present a continuous record of the asian monsoon over the last 16 ka from 18o measurements of stalagmite calcite over 900 oxygen isotopic measurements providing information on shifts in monsoon precipitation are combined with a chronology from 45 precise 230th dates 18o and therefore asian monsoon intensity generally follows changes in insolation although changes in 18o are generally accommodated in abrupt shifts in contrast to smoothly varying insolation indicating that threshold effects may be important 18o decreased dramatically 3 at the start of the holocene 11 5 ka and remained low for 6 ka four positive 18o events centered at 11225 97 yr bp 1 05 10880 117 yr bp 1 15 9165 75 yr bp 1 4 and a double event centered at 8260 64 yr bp 1 1 and 8080 74 yr bp 1 0 punctuated this period of high monsoon intensity all four events correlate within error with climate changes in greenland ice cores thus the relationship between the asian monsoon and the north atlantic observed during the glacial period appears to continue into the early holocene in addition three of the four events correlate within error with outburst events from lake agassiz the decline of monsoon intensity in the mid late holocene is characterized by an abrupt positive shift in 18o which occurs at 3550 59 yr bp 1 1 in 100 yr in addition the holocene is punctuated by numerous centennial and multi decadal scale events amplitudes 0 5 to 1 up to half the amplitude of the glacial interstadial events seen in the last glacial period thus holocene centennial and multi decadal scale monsoon variability is significant although not as large as glacial millennial scale variability the monsoon shows a strong connection with northern south american hydrological changes related by changes in itcz position spectral analysis of the 18o record shows significant peaks at solar periodicities of 208 yr and 86 yr suggesting variation is influenced by solar forcing however there are numerous other significant peaks including peaks at el nino frequencies observed for high resolution portions of the record between 8110 and 8250 yr which suggest that changes in oceanic and atmospheric circulation patterns in addition to those forced by solar changes are important in controlling holocene monsoon climate in addition for this high resolution portion we observe a distinctive biennial oscillation of the asian monsoon which has been associated with the tropospheric biennial oscillation tbo

changes of climate glaciers and runoff in china s monsoonal temperate glacier region during the last several decades changes of climate glaciers and runoff during the last several decades in china s monsoonal temperate glacier region have been studied temperature has increased in a fluctuating manner during the last several decades and temperature rise has accelerated since the 1980s net accumulation of dasuopu ice core has consistently declined and the precipitation decrease was also obvious from the end of 1970s through the middle 1980s and particularly after the 1990s in china s monsoonal temperate glacier region as a response to climate change eight monsoonal temperate glaciers were stationary or advancing between the 1900s 1930s and the 1960s 1980s and were in retreat from the 1930s to the 1960s and from the 1980s to the present ablation is heavy in the glacier tongue areas and the mean ablation water equivalent in hailuogou glacier during 1990 91 1997 98 was 876 mm more than that in 1982 83 ablation depth on the exposed ice area increased by 1 4 m a 1 over the period 1983 84 1990 91 mass balance records also show that glaciers suffered a constant mass loss of snow and ice and the accumulated mass balance in hailuogou basin and baishui glacier no 1 was 10 83 m water equivalent in the past 45 years and 11 38 m in the past 52 years as glaciers become shorter narrower and thinner under the background of climate warming changes of internal and upper surface morphology also occurred providing evidence of the response to climatic warming in recent years local hydrological and climatic data demonstrated that in yanggong basin during 1979 2003 and hailuogou basin during 1988 2004 runoff from the glacier areas has been increasing both seasonally and annually overall it is clear that china s monsoonal temperate glaciers are losing mass and are retreating under the background of climate warming c 2009 elsevier ltd and inqua all rights reserved

timing of fluvial terrace formation and concomitant travertine deposition in the upper sutlej river tirthapuri southwestern tibet and paleoclimatic implications abstract travertines are carbonates precipitated from hydrothermal springs and are relatively common on the tibetan plateau and occur along tectonically active faults the karakoram fault system is an active strike slip fault that extends from the pamir into southwestern tibet where it controls the course of the upper sutlej river and the occurrence of several hydrothermal springs including the tirthapuri hot springs multiple fluvial terraces that are partly capped by travertine are preserved in the tirthapuri area four main fluvial terrace levels labelled as t1 to t4 with increasing height above river were identified and several meter thick travertine platforms occur on the current river level as well as the t2 and t3 terraces sedimentological and petrographic observations suggest that the travertine platforms were deposited on active floodplains of the paleo and modern sutlej river and preserved from fluvial erosion because travertine precipitation was immediately followed by vertical river bed incision and thus terrace abandonment results of 230th u in combination with luminescence dating show that the deposition of travertine platform and river incision that led to the formation of t3 terrace 93 m above the sutlej took place at ca 127 5 ka the development of terrace t2 and overlying travertine platform 28 m above the sutlej occurred between ca 10 0 and 8 8 ka fluvial incision has arrived at the modern level at least ca 0 2 ka ago both the travertine deposition and major river incision are likely triggered by the intensified indian summer monsoon and are linked to phases of maximum monsoon strength during strong monsoon phases a large quantity of moisture is transported into southwestern tibet activating hot springs and thus travertine precipitation facilitating fluvial incision and stripping off sediments from the regional hill slopes at least over the last glacial cycle we suggest that the tirthapuri travertine and associated fluvial incision are sensitive indicators of peak monsoonal activity and can thus provide valuable insights into past climate change and climate driven landscape evolution on the southwestern tibetan plateau comparison of our findings with published data further suggests that monsoon controlled fluvial aggradation and incision during the early holocene is synchronous in southwestern tibet and the adjacent sector of the himalayan orogen north western sub to high himalaya

global patterns of loss of life from landslides global loss of life from landslides is poorly quantifi ed a global data set of fatalities from nonseismically triggered landslides that resulted in loss of life between a d 2004 and 2010 permits for the fi rst time proper quantifi cation of impacts and spatial distributions in total 2620 fatal landslides were recorded worldwide during the 7 yr period of the study causing a total of 32 322 recorded fatalities these total numbers of landslides and victims are an order of magnitude greater than other data sets have indicated but analysis of the data suggests that it may still slightly underestimate the true human costs the majority of human losses occur in asia especially along the himalayan arc and in china this geographical concentration dominates the annual landslide cycle which peaks in the northern hemisphere summer months finally numbers of fatalities per event show a fat tailed power law distribution with the density of landslides being moderately correlated with the population density on a national basis

influence of slope inclination on the triggering and distal reach of hydraulically induced flow slides abstract in the absence of water a dry granular landslide mass released on an incline will experience greater acceleration than an otherwise identical mass released on a plane of lower inclination however when water is introduced to the system the outcome is more complicated while it requires less water pressure to trigger a landslide on a steep slope the additional saturated soil in a gentle slope can make it more susceptible to flow liquefaction which in turn can make it the slope of greater risk in terms of the landslide velocity and distal reach results from seven geotechnical centrifuge tests were evaluated to compare the behavior of flow slides triggered in a loose granular soil layer inclined at 20 and 30 the results indicate that the influence of slope inclination on mobility is highly dependent on antecedent groundwater conditions in low antecedent groundwater scenarios the mobility of the failures triggered in the 20 and 30 were similar however in a high antecedent groundwater scenario a flow slide triggered on the 20 slope was observed to travel twice the distance and reaching nearly twice the maximum velocity than a flow slide triggered on the steeper 30 slope these results provide experimental data documenting the complex interaction between slope inclination and antecedent groundwater conditions to control the triggering and distal reach of hydraulically induced flow slides

morphodynamics and lake level variations at paiku co southern tibetan plateau china abstract proxy records from lakes on the tibetan plateau are commonly used to infer monsoon related climatic changes during the late quaternary specific influences of catchment processes and their interaction with the lake basin are seldom utilized based on morphological field investigations supported by remote sensing analyses in combination with radiocarbon dated sediment data from lacustrine sequences along paleoshorelines and terraces we can demonstrate that close relationships exist between glacier dynamics fluvial alluvial fan terrace formation and lake level and lake area changes of paiku co southern tibet our results show that the formation of large scale fluvial alluvial fans f1 predates the maximum advance of the xixiabangma glaciers the latter formed a distinct terminal moraine complex north of the present glaciers during the local lgm llgm at 42 21 cal ky bp a younger fan generation f2 developed from the llgm to the late holocene which was accompanied by lake level fluctuations with a generally decreasing trend the highest morphologically traceable lake level at 4665 m asl existed prior to 25 cal ky bp and induced a potential overflow to the neighboring langqiang co and pengqu river a high level also existed during the llgm followed by a minor decline until ca 15 cal ky bp owing to reduced meltwater discharge under cold and dry climatic conditions a return to the previous level during the late glacial early holocene period between 11 9 and 9 5 cal ky bp is likely caused by climate warming increased meltwater discharge and enhanced indian summer monsoon ism moisture supply afterwards paiku co shrank gradually toward its present level while the youngest fan f3 generation evolved as individual small sized bodies under ephemeral discharge conditions from the mid holocene to the present the formation of four terrace levels t4 1 is likely the result of sequential incision into the fan generations with a mean erosion rate of 50 cm ky caused by lake level lowering tectonic impact cannot be completely ruled out since 1976 the glaciers lost ca 15 in area accompanied by lake area loss of 3 7 between 1972 and june 2014 seasonal lake level variations of about 1 2 m in height occur in response to summer monsoon rainfall our data show a close interaction between glacial dynamics fluvial processes terrace formation and water budget changes throughout the last 25 cal ky bp in response to the well known insolation driven ism effective moisture supply during the late glacial and holocene period temperature driven meltwater dynamics were the controlling factors for variations in water balance of paiku co

examination of the seepage face boundary condition in subsurface and coupled surface subsurface hydrological models a seepage face is a nonlinear dynamic boundary that strongly affects pressure head distributions water table fluctuations and flow patterns its handling in hydrological models especially under complex conditions such as heterogeneity and coupled surface subsurface flow has not been extensively studied in this paper we compare the treatment of the seepage face as a static dirichlet versus dynamic boundary condition we assess its resolution under conditions of layered heterogeneity we examine its interaction with a catchment outlet boundary and we investigate the effects of surface subsurface exchanges on seepage faces forming at the land surface the analyses are carried out with an integrated catchment hydrological model numerical simulations are performed for a synthetic rectangular sloping aquifer and for an experimental hillslope from the landscape evolution observatory the results show that the static boundary condition is not always an adequate stand in for a dynamic seepage face boundary condition especially under conditions of high rainfall steep slope or heterogeneity that hillslopes with layered heterogeneity give rise to multiple seepage faces that can be highly dynamic that seepage face and outlet boundaries can coexist in an integrated hydrological model and both play an important role and that seepage faces at the land surface are not always controlled by subsurface flow the paper also presents a generalized algorithm for resolving seepage face outflow that handles heterogeneity in a simple way is applicable to unstructured grids and is shown experimentally to be equivalent to the treatment of atmospheric boundary conditions in subsurface flow models

holocene lake level variations of longmu co western qinghai tibetan plateau longmu co is surrounded by conspicuous regressive shorelines attesting to high water levels in the past in this study we dated paleoshoreline sediments around the lake using optically stimulated luminescence osl infrared stimulated luminescence irsl and radiocarbon dating then explored the forces that drove holocene lake level variations we found that 1 osl irsl ages are consistent with geomorphic sequences and some extant cosmogenic and u th shoreline ages however inorganic evaporite crust 14c ages are much older than corresponding osl irsl ages due to varying lake reservoir effects and should be used with caution 2 the highest lake levels of longmu co 160 145 m above present lasted from 12 8 to 11 3 ka two periods of abrupt lake level declines occurred at 11 3 and 7 4 ka lake level dropped 44 and 45 m respectively with a gradual regression of 18 m between these two intervals the lake expanded moderately from 7 to 5 5 ka then declined once more after 5 5 ka with this regression accelerating during the last 1 5 ka 3 the deglacial lake level transgression was likely due to glacier melt waters the indian summer monsoon reached the longmu co watershed and brought precipitation during the early holocene middle to late holocene lake regression was caused by the retreat of the monsoon and consequent environmental deterioration

response of lake catchment processes to holocene climate variability evidences from the ne tibetan plateau abstract investigating the so called third pole environment tpe became a major concern during the last decades since it was recognized that the high altitude region of the tibetan plateau tp is a key area for the understanding of cause effect mechanisms driven by climate change and geodynamic processes studies on the hydro climatic evolution during the late quaternary were mainly carried out by single lake records or alternatively by individual terrestrial sites integrated source to sink studies considering lake catchment interactions were extremely seldom utilized we investigated such relationships in the kuhai basin on the north eastern tibetan plateau and analysed sedimentary processes based on 30 onshore sections and three sediment cores from different locations and water depth in the lake basin grain size variations ostracod assemblages geochemical proxies and absolute dating luminescence radiocarbon 210pb 137cs were applied as key indicators that reveal interacting sediment fluxes under different hydro climatic settings during the younger dryas interval and the holocene our results indicate that wind induced transportation processes and allocation of respective aeolian sands in the catchment are attributed to distinct phases of reduced effective moisture availability during summer time those phases corresponded to weak summer monsoon influence during the younger dryas interval the early holocene 11 6 7 5 ka dry cold interlude dci ca 4 5 3 0 ka dark ages cold period dacp ca 1 8 1 1 ka and the little ice age lia ca 0 6 0 1 ka contemporaneous low lake levels during these periods corresponded with respective aeolian sand flux and variable composition of mixed sediments fluvial and aeolian in lake deposits different flux rates at the core sites could be assigned to local conditions in respect to inflow behaviour of individual drainage systems and nearshore morphology aeolian deposits in the catchment were not always preserved and underwent re mobilisation during succeeding episodes and or erosion during phases of high water availability wetter climatic conditions during the mid holocene ca 7 5 5 1 ka roman warm period rwp ca 2 8 1 5 ka and medieval climate anomaly mca ca 0 9 0 6 ka revealed significant lake level rise due to enhanced river discharge well documented by highest suspended flux rates disappearance of ostracod communities at core sites and very low sand input climate shifts during the holocene were linked to variations in effective moisture supply under the influence of the asian summer monsoon asm and the interplay with the mid latitude westerlies mlw cold dry phases were likely a response to north atlantic climatic anomalies transmitted by the mlw across the tp