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

prediction of the behaviour of landslide dams using a geomorphological dimensionless index landslide dams are a common phenomenon they form when a landslide reaches the bottom of a river valley causing a blockage the first effect of such a dam is the infilling of a lake that inundates the areas upstream while the possibility of a sudden dam collapse with a rapid release of the impounded waters poses a higher flood risk to the downstream areas the results of the main inventories carried out to date on landslide dams have been examined to determine criteria for forecasting landslide dam evolution with particular emphasis on the assessment of dam stability not all landslides result in the blockage of a river channel this only occurs with ones that can move a large amount of material with moderate or high velocities in most cases these landslides are triggered by rainfall events or high magnitude earthquakes a relationship also exists between the volume of the displaced material and the landslide dam stability several authors have proposed that landslide dam behaviour can be forecast by defining various geomorphological indexes that result from the combination of variables identifying both the dam and the dammed river channel further developments of this geomorphological approach are presented in this paper by the definition of a dimensionless blockage index starting with an analysis of 84 episodes selected worldwide it proved to be a useful tool for making accurate predictions concerning the fate of a landslide dam copyright 2002 john wiley sons ltd

global sea level rise published values for the long term global mean sea level rise determined from tide gauge records exhibit considerable scatter from about 1 mm to 3 mm yr this disparity is not attributable to instrument error long term trends computed at adjacent sites often agree to within a few tenths of a millimeter per year instead the differing estimates of global sea level rise appear to be in large part due to authors using data from gauges located at convergent tectonic plate boundaries where changes of land elevation give fictitious sea level trends in addition virtually all gauges undergo subsidence or uplift due to postglacial rebound pgr from the last deglaciation at a rate comparable to or greater than the secular rise of sea level modeling pgr by the ice 3g model of tushingham and peltier 1991 and avoiding tide gauge records in areas of converging tectonic plates produces a highly consistent set of long sea level records the value for mean sea level rise obtained from a global set of 21 such stations in nine oceanic regions with an average record length of 76 years during the period 1880 1980 is 1 8 mm yr 0 1 this result provides confidence that carefully selected long tide gauge records measure the same underlying trend of sea level and that many old tide gauge records are of very high quality

onset of recent rapid sea level rise in the western atlantic ocean a high resolution record of sea level change spanning the past 1000 years is derived from foraminiferal and chronological analyses of a 2 m thick salt marsh peat sequence at chezzetcook nova scotia canada former mean tide level positions are reconstructed with a precision of 0 055 m using a transfer function derived from distributions of modern salt marsh foraminifera our age model for the core section older than 300 years is based on 19 ams 14c ages and takes into account the individual probability distributions of calibrated radiocarbon ages the past 300 years is dated by pollen and the isotopes 206pb 207pb 210pb 137cs and 241am between ad 1000 and ad 1800 relative sea level rose at a mean rate of 17 cm per century apparent pre industrial rises of sea level dated at ad 1500 1550 and ad 1700 1800 cannot be clearly distinguished when radiocarbon age errors are taken into account furthermore they may be an artefact of fluctuations in atmospheric 14c production in the 19th century sea level rose at a mean rate of 1 6 mm yr between ad 1900 and ad 1920 sea level rise accelerated to the modern mean rate of 3 2 mm yr this acceleration corresponds in time with global temperature rise and may therefore be associated with recent global warming 2005 elsevier ltd all rights reserved

coupling instrumental and geological records of sea level change evidence from southern new england of an increase in the rate of sea level rise in the late 19th century 1 we construct a high resolution relative sea level record for the past 700 years by dating basal salt marsh peat samples above a glacial erratic in an eastern connecticut salt marsh to test whether or not the apparent recent acceleration in the rate of sea level rise slr is coeval with climate warming the data reveal an average slr rate of 1 0 0 2 mm year from about 1300 to 1850 a d coupling of the regional tide gauge data 1856 to present with this marsh based record indicates that the nearly three fold increase in the regional rate of slr to modern levels likely occurred in the later half of the 19th century thus the timing of the observed slr rate increase is coincident with the onset of climate warming indicating a possible link between historic slr increases and recent temperature increases

worldwide initiation of holocene marine deltas by deceleration of sea level rise radiocarbon dated deltaic sequences of holocene age from different parts of the world began to accumulate within a restricted time range from about 8500 to 6500 years ago evaluation of major delta processes indicates that deceleration in sea level rise was the key factor in holocene delta formation within many deltas there is as much as a 2000 year age range between basal deposits in seaward and landward cores this age difference records the progressive landward migration of near mean sea level depositional environments during the lower to mid holocene establishment of a chronostratigraphic framework for holocene delta development provides a fundamental global baseline for distinguishing sea level change from vertical land motion by tectonism and isostasy and for evaluating rates of future marine incursion into low lying deltas

evaluation of prediction capability of the artificial neural networks for mapping landslide susceptibility in the turbolo river catchment northern calabria italy abstract landslides are one of the most widespread natural hazards that cause damage to both property and life every year and therefore the spatial distribution of the landslide susceptibility is necessary for planning future developmental activities in this paper the artificial neural network ann technique is tested for developing a landslide susceptibility map in turbolo river catchment north calabria south italy landslides were mapped through air photo interpretation and field surveys by identifying both the landslide depletion zones dzs and accumulation zones azs and relevant geo environmental thematic layers pertaining to landslide predisposing factors were generated using air photo interpretation field surveys and geographic information system gis tools ten predisposing factors were related to the occurrence of landslide lithology faults land use drainage network and a series of topographic factors elevation slope aspect plan curvature topographic wetness index twi and stream power index spi in order to evaluate and validate landslide susceptibility the dzs were divided in two groups using a random partition strategy the first group training set was used to prepare the susceptibility map employing a back propagation learning algorithm in the idrisi taiga software the second group testing set was used to validate the landslide susceptibility model using the confusion matrix and the receiver operating characteristic roc curve the susceptibility map was classified into five susceptibility classes very low low moderate high and very high about 46 of the study area falls in high to very high susceptible classes and most of the dzs mapped 87 3 occur in the same classes the validation results showed satisfactory agreement between the susceptibility map and the dzs locations over 85 of the dzs of the validation set are correctly classified falling in high and very high susceptibility areas also the roc curve had shown an area under curve auc value of 0 90 which demonstrates the robustness and good reliability of the landslide susceptibility model according to these results we conclude that the map produced by the artificial neural network is reliable and the methodology applied in the study produced high performance and satisfactory results which may be useful for land planning policy

ancient egyptian mummified shrews mammalia eulipotyphla soricidae and mice rodentia muridae from the spanish mission to dra abu el naga and their implications for environmental change in the nile valley during the past two millennia

the estimation of global sea level change a problem of uniqueness an objective method of estimating regional averages of coherent sea level sl change is developed the technique is applied to a large set of sl data representative of most of the world s continental margins the results show highly coherent sl changes over many of the regions studied the method is then applied to the regional averages themselves to develop an overall estimate of the coherent pattern of sl variations existing in the historical sl data set the pattern is characterized by a coherent rise of sl in all regions except alaska scandinavia both areas of notorious crustal uplift and southeast asia where sl appears to be falling the analysis suggests little or no change in sl prior to the early 1900 s the period since that time has seen an increase in sl that is optimally fit by a linear trend of 23 cm century the study results suggest that it is not possible to uniquely determine either a global rate of change of sl or even the average rate of change associated with the existing inadequate data set indeed different analysis methods by themselves can cause 50 variations in the estimates of sl trend in the existing data set a signal noise analysis suggests it should be easy to detect small future changes in the sl trends estimated for the period 1930 1980 however detection of theoretically predicted low frequency signals e g caused by co2 warming will be difficult in view of the huge low frequency natural variability associated with glacial tectonic processes

medieval warming little ice age and european impact on the environment during the last millennium in the lower hudson valley new york usa establishing natural climate variability becomes particularly important in large urban areas in anticipation of droughts we present a welldated bi decadal record of vegetation climate land use and fire frequency from a tidal marsh in the hudson river estuary the classic medieval warm period is evident through striking increases in charcoal and pinus dominance from 800 1300 a d paralleling paleorecords southward along the atlantic seaboard higher inputs of inorganic sediment during this interval suggest increased watershed erosion during drought conditions the presence of the little ice age ensues with increases in picea and tsuga coupled with increasing organic percentages due to cooler moister conditions european impact is manifested by a decline in arboreal pollen due to land clearance increased weedy plant cover i e ambrosia plantago and rumex and an increase in inorganic particles to the watershed

the formation and failure of natural dams of the numerous kinds of dams that form by natural processes dams formed from landslides glacial ice and late neoglacial moraines present the greatest threat to people and property landslide dams form in a wide range of physiographic settings the most common types of mass movements that form landslide dams are rock and debris avalanches rock and soil slumps and slides and mud debris and earth flows the most common initiation mechanisms for dam forming landslides are excessive rainfall and snowmelt and earthquakes landslide dams can be classified into six categories based on their relation with the valley floor type i dams 11 of 184 landslide dams from around the world that we were able to classify do not reach from one valley side to the other type ii dams 44 span the entire valley floor in some cases depositing material high on opposite valley sides type iii dams 41 move considerable distances both upstream and downstream from the landslide failure type iv dams 1 are rare and involve the contemporaneous failure of material from both sides of a valley type v dams 1 also are rare and are created when a single landslide sends multiple tongues of debris into a valley and forms two or more landslide dams in the same reach of river type vi dams 3 involve one or more failure surfaces that extend under the stream or valley and emerge on the opposite valley side many landslide dams fail shortly after formation in our sample of 73 documented landslide dam failures 27 of the landslide dams failed less than 1 day after formation and about 50 failed within 10 days over topping is by far the most common cause of failure the timing of failure and the magnitude of the resulting floods are controlled by dam size and geometry material characteristics of the blockage rate of inflow to the impoundment size and depth of the impoundment bedrock control of flow and engineering controls such as artificial spill ways diversions tunnels and planned breaching by blasting or conventional excavation glacial ice dams can produce at least nine kinds of ice dammed lakes the most dangerous are lakes formed in main valleys dammed by tributary glaciers failure can occur by erosion of a drainage tunnel under or through the ice dam or by a channel over the ice dam cold polar ice dams generally drain supraglacially or marginally by downmelting of an outlet channel warmer temperate ice dams tend to fail by sudden englacial or subglacial breaching and drainage late neoglacial moraine dammed lakes are located in steep mountain areas affected by the advances and retreats of valley glaciers in the last several centuries these late neoglacial dams pose hazards because 1 they are sufficiently young that vegetation has not stabilized their slopes 2 many dam faces are steeper than the angle of repose 3 these dams and lakes are immediately downslope from steep crevassed glaciers and near vertical rock slopes and 4 downstream from these dams are steep canyons with easily erodible materials that can be incorporated in the flow and increase flood peaks the most common reported failure mechanism is overtopping and breaching by a wave or series of waves in the lake generated by icefalls rockfalls or snow or rock avalanches melting of ice cores or frozen ground and piping and seepage are other possible failure mechanisms natural dams may cause upstream flooding as the lake rises and downstream flooding as a result of failure of the dam although data are few for the same potential energy at the dam site ownstream flood peaks from the failure of glacier ice dams are smaller than those from landslide moraine and structed earth fill and rock fill dam failures moraine dam failures appear to produce some of the largest downstream flood peaks for potential energy at the dam site greater than 1011 1012 joules differences in flood peaks natural dam failures appear to be controlled by dam characteristics and failure mechanisms

objective landslide detection and surface morphology mapping using high resolution airborne laser altimetry a map of extant slope failures is the most basic element of any landslide assessment without an accurate inventory of slope instability it is not possible to analyze the controls on the spatial and temporal patterns of mass movement or the environmental human or geomorphic consequences of slides landslide inventory maps are tedious to compile difficult to make in vegetated terrain using conventional techniques and tend to be subjective in addition most landslide inventories simply outline landslide boundaries and do not offer information about landslide mechanics as manifested by internal deformation features in an alternative approach we constructed accurate high resolution dems from airborne laser altimetry lidar data to characterize a large landslide complex and surrounding terrain near christchurch new zealand one dimensional circular 2 d and spherical 3 d statistics are used to map the local topographic roughness in the dems over a spatial scale of 1 5 to 10 m the bedrock landslide is rougher than adjacent unfailed terrain and any of the statistics can be employed to automatically detect and map the overall slide complex furthermore statistics that include a measure of the local variability of aspect successfully delineate four kinematic units within the gently sloping lower half of the slide features with a minimum size of surface folds that have a wavelength of about 11 to 12 m and amplitude of about 1 m are readily mapped two adjacent earthflows within the landslide complex are distinguished by a contrast in median roughness and texture and continuity of roughness elements the less active of the earthflows has a surface morphology that presumably has been smoothed by surface processes the laplacian operator also accurately maps the kinematic units and the folds and longitudinal levees within and at the margins of the units finally two dimensional power spectra analyses are used to quantify how roughness varies with length scale these results indicate that no dominant length scale of roughness exists for smooth unfailed terrain in contrast zones with different styles of landslide deformation exhibit distinctive spectral peaks that correspond to the scale of deformation features such as the compression folds the topographic based analyses described here may be used to objectively delineate landslide features generate mechanical inferences about landslide behavior and evaluate relatively the recent activity of slides published by elsevier science b v

the long sea level record at cadiz southern spain from 1880 to 2009 1 mean sea level observations from an historical tide gauge located in cadiz southern spain spanning the period 1880 1924 were recovered from national archives daily sea level averages stored in handwritten log books were digitized quality controlled and referred to the same benchmark a careful analysis of all the high precision leveling surveys available in the area of the tide gauge enabled the establishment of a common datum with a modern record starting in 1961 from another tide gauge located only 2 5 km apart with accuracy better than 5 mm as a result a consistent daily mean sea level record from 1880 to 2009 was constructed the 20th century relative mean sea level rise in cadiz is 0 7 0 1 mm yr 1 which becomes 1 0 0 2 mm yr 1 once corrected for vertical land movement with high precision gps data in agreement with nearby records the analysis of the seasonal sea level cycle indicated that the amplitude of the annual cycle has increased during the 20th century this work evidences the significance of sea level data rescue for present day climate research

preliminary analysis of acceleration of sea level rise through the twentieth century using extended tide gauge data sets august 2014 this work explores the potential for extending tide gauge time series from the permanent service for mean sea level psmsl using historical documents psmsl ancillary data and by developing additional composite time series using near neighbor tide gauges the aim was to increase the number completeness and geographical extent of records covering most or all of the twentieth century the number of at least 75 complete century scale time series have been approximately doubled over the original psmsl data set in total over 4800 station years have been added with 294 of these added to 10 long southern hemisphere records individual century scale acceleration values derived from this new extended data set tend to converge on a value of 0 01 0 008 mm yr2 this result agrees closely with recent work and is statistically significant at the 1 sigma level possible causes of acceleration and errors are briefly discussed results confirm the importance of current data archeology projects involving digitization of the remaining archives of hard copy tide gauge data for sea level and climate studies

analysis of landslide dams induced by the 2008 wenchuan earthquake abstract landslide dams caused by earthquakes are extremely hazardous disruptions of the flow of water and sediment in mountain rivers capable of delivering large outburst floods that may devastate downstream areas we analyzed a unique inventory of 828 landslide dams triggered by the m w 7 9 2008 wenchuan tectonic earthquake china constituting 1 4 of the 60 000 coseismic slope failures mapped and attributed to this event while 501 landslides blocked the rivers completely the remainder caused only partial damming or channel diversion the spatial distribution of landslide dams follows the same trend of that of the total landslide distribution with landslide dams being most abundant in the steep watersheds of the hanging wall of the yingxiu beichuan thrust fault and in the northeastern part of the strike slip fault near qingchuan besides the co seismic landslide density the river width also played a key role in determining the landslide dam formation narrow rivers are more prone to be dammed than the wide rivers the correlation between river width and landslide dam volume follows a linear relation which can be used to roughly estimate the dam formation possibility however the applicability of this correlation needs to be validated in other regions the decay failure rate of dams defined here as the percentage of the number and area of landslide dams that have failed over time shows that 25 of dams accounting for 30 of total landslide dam area failed one week after the earthquake these percentages increased to 60 within 1 month and to 90 within 1 year the geomorphometric parameters were analyzed revealing power law relations between landslide area and dam width landslide source area and dam area as well as lake area and lake volume the inventory presented in this study will enrich the worldwide earthquake induced landslide dam database and will also contribute to a better understanding of the post earthquake dam decay

discriminant analysis of the geomorphic characteristics and stability of landslide dams article i nfo landslides can cause the formation of dams but these dams often fail soon after lake formation thus rapidly evaluating the stability of a landslide dam is crucial for effective hazard mitigation this study utilizes discriminant analysis based on a japanese dataset consisting of 43 well documented landslide dams to determine the significant variables including log transformed peak flow or catchment area and log transformed dam height width and length in hierarchical order which affect the stability of a landslide dam the high overall prediction power 88 4 of the 43 training cases are correctly classified and the high cross validation accuracy 86 demonstrate the robustness of the proposed discriminant models phwl with variables including log transformed peak flow and log transformed dam height width and length and ahwl with variables including log transformed catchment area and log transformed dam height width and length compared to a previously proposed dbi index based graphic approach the discriminant model ahv which uses the log transformed catchment area dam height and dam volume as relevant variables shows better ability to evaluate the stability of landslide dams although these discriminant models are established using a japanese dataset only the present multivariate statistical approach can be applied for an expanded dataset without any difficulty when more completely documented worldwide landslide dam data are available

the african humid period and the record of marine upwelling from excess 230th in ocean drilling program hole 658c using a high resolution 230 th normalized record of sediment flux we document the deglacial and holocene history of north african aridity and coastal upwelling at ocean drilling program hole 658c at both the end of the younger dryas and after the 8 2 ka event there are significant drops in terrigenous accumulation at our site indicating an increase in the monsoon moisture flux over africa at this time at 5 5 ka there is an abrupt end to the african humid period and a return to stronger upwelling conditions for carbonate and opal fluxes the 230 th normalization completely changes the shape of each record based on percentage variations alone this site is a clear example of how variations in one sediment component can obscure changes in the others and it demonstrates the need for radionuclide measurements more generally in paleoceanography by taking our new records and a large amount of previous data from this site we conclude that increases in african moisture are tightly coupled to decreases in coastal upwelling intensity

the formation and breaching of a short lived landslide dam at hsiaolin village taiwan part ii simulation of debris flow with landslide dam breach abstract typhoon morakot 2009 caused serious damage in southern taiwan due to intensive rainfall with long duration the issue of greatest concern arising from the disasters brought about by this extreme event was the burying of the entire village of hsiaolin by a massive debris flow and landslide based on seismological and near surface magnetic data this tragic scenario arose due to a combination of events a massive landslide the formation of a landslide dam and the consequent debris flow when this dam was breached the objective of this part of the study is to investigate the spatial and temporal characteristics of the debris flow induced by the landslide breach the us national weather service breach model and the federal emergency management agency approved flo 2d model are integrated to facilitate the investigation of this catastrophe a series of simulations including a 2d rainfall runoff simulation over the cishan river basin landslide dam breach routing and 2d debris flow simulation around the hsiaolin village were conducted hydraulic calculations were performed to determine the equivalent top elevation of the landslide dam based on inflows computed from the 2d rainfall runoff simulation in association with the digital terrain model dtm and upstream constraint of the backwater inundation areas the hydrograph of the upstream inflow which induced overtopping failure was provided by a 2d rainfall runoff simulation using the flo 2d model calibrated by comparison with the downstream discharge record the longevity of the landslide dam was less than 1 h and it took only about 8 minutes to completely breach the peak discharge rate of this massive landslide dam breach was 70 649 m3 s the dam break hydrograph was then used for upstream inflow to drive the flo 2d debris flow simulation the average sediment concentration by volume was 0 362 the simulated deposited sediment depth showed a reasonable match to the differences of dtms before and after the disaster

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

abrupt onset and termination of the african humid period rapid climate responses to gradual insolation forcing a detailed ca 100 yr resolution and well dated 18 ams 14 c dates to 23 cal ka bp record of latest pleistocene holocene variations in terrigenous eolian sediment deposition at odp site 658c off cap blanc mauritania documents very abrupt large scale changes in subtropical north african climate the terrigenous record exhibits a well defined period of low influx between 14 8 and 5 5 cal ka bp associated with the african humid period when the sahara was nearly completely vegetated and supported numerous perennial lakes an arid interval corresponding to the younger dryas chronozone punctuates this humid period the african humid period has been attributed to a strengthening of the african monsoon due to gradual orbital increases in summer season insolation however the onset and termination of this humid period were very abrupt occurring within decades to centuries both transitions occurred when summer season insolation crossed a nearly identical threshold value which was 4 2 greater than present these abrupt climate responses to gradual insolation forcing require strongly non linear feedback processes and current coupled climate model studies invoke vegetation and ocean temperature feedbacks as candidate mechanisms for the non linear climate sensitivity the african monsoon climate system is thus a low latitude corollary to the bi stable behavior of high latitude deep ocean thermohaline circulation which is similarly capable of rapid and large amplitude climate transitions

transient water and sediment storage of the decaying landslide dams induced by the 2008 wenchuan earthquake china article earthquake triggered landslide dams are potentially dangerous disrupters of water and sediment flux in mountain rivers and capable of releasing catastrophic outburst flows to downstream areas we analyze an inventory of 828 landslide dams in the longmen shan mountains china triggered by the mw 7 9 2008 wenchuan earthquake this database is unique in that it is the largest of its kind attributable to a single regional scale triggering event 501 of the spatially clustered landslides fully blocked rivers while the remainder only partially obstructed or diverted channels in steep watersheds of the hanging wall of the yingxiu beichuan fault zone the size distributions of the earthquake triggered landslides landslide dams and associated lakes a can be modeled by an inverse gamma distribution b show that moderate size slope failures caused the majority of blockages and c allow a detailed assessment of seismically induced river blockage effects on regional water and sediment storage monte carlo simulations based on volumetric scaling relationships for soil and bedrock failures respectively indicate that 14 18 of the estimated total coseismic landslide volume of 6 4 14 6 10 9 m 3 was contained in landslide dams representing only 1 4 of the 60 000 slope failures attributed to the earthquake these dams have created storage capacity of 0 6 10 9 m 3 for incoming water and sediment about 25 of the dams containing 2 of the total river blocking debris volume failed one week after the earthquake these figures had risen to 60 20 and 90 90 within one month and one year respectively thus also emptying 92 of the total potential water and sediment storage behind these dams within one year following the earthquake currently only 0 08 10 9 m 3 remain available as natural reservoirs for storing water and sediment while 0 19 10 9 m 3 i e about a third of the total river blocking debris volume has been eroded by rivers dam volume and upstream catchment area control to first order the longevity of the barriers and bivariate domain plots are consistent with the observation that most earthquake triggered landslide dams were ephemeral we conclude that the river blocking portion of coseismic slope failures disproportionately modulates the post seismic sediment flux in the longmen shan on annual to decadal timescales

100 000 years of african monsoon variability recorded in sediments of the nile margin abstract multiproxy analyses were performed on core ms27pt recovered in hemipelagic sediments deposited on the nile margin in order to reconstruct nile river palaeohydrological fluctuations during the last 100 000 years the strontium and neodymium isotope composition of the terrigenous fraction and the major element distribution reveal large and abrupt changes in source oscillating between a dominant aeolian saharan contribution during arid periods and a dominant nile river contribution during pluvial periods iron content shows a strong correlation with strontium and neodymium isotopes this allows the use of a high resolution continuous fe record as a proxy of blue nile sediment input over the last 100 000 years the detailed fe record with approximately 10 years resolution during pluvial periods is consistent with subtropical african records of well dated lake level fluctuations and thus constitutes a first continuous high resolution record of the east african monsoon regime intensity over ethiopia the detailed fe record shows the two main known pluvial periods attributed to strengthening of the african monsoon over ethiopia the nabtian period from 14 to 8 ka cal bp and the saharan period from 98 to 72 ka bp for the first time the last glacial period marine isotope stage mis 2 3 and 4 is documented with a continuous record showing large oscillations between high and low east african palaeo monsoon regimes the end of the nabtian period occurred at 8 ka in core ms27pt i e much earlier than on the east equatorial african region where it ended around 5 5 ka we interpret this as evidence that the southward shift of the rain belt occurred 3000 years earlier over the eastern ethiopian highland and propose that the gradual southward migration of the rain belt was associated with highly variable intensity and longer rainy seasons from 8 to 5 ka during the last glacial period two wet periods are present around 60 50 ka bp and 38 30 ka bp these two humid periods are in phase with the rise of atmospheric ch4 concentrations suggesting that wetland tropical african area was one of the sources of the atmospheric ch4 during the mis 3 during the last glacial maximum and mis 4 high saharan aeolian influxes in phase with records of aeolian dust deposited in east antarctica are documented this study highlights the importance of reconstructions of monsoon rainfall fluctuation at high temporal resolution to better understand the link between low and high latitude climate variability at millennial timescales

late quaternary environments and prehistoric occupation in the lower white nile valley central sudan abstract despite the major contributions provided over fifty years ago by a j arkell and j d tothill to our understanding of late quaternary environments and prehistoric occupation near the confluence of the blue and white nile in central sudan three key questions have remained unresolved since then a was the decline in nile flood levels from early holocene times onwards caused by a reduction in nile discharge or by channel incision or both b was the regional climate wetter during times of high nile floods and drier during times of low nile floods c given the high degree of disturbance of mesolithic and later prehistoric sites is it possible to identify primary context stratified and undisturbed occupation drawing upon dated evidence from three sites to the east of and three to the west of the lower white nile we provide a qualified answer to the first question and documented affirmative answers to the second and third questions

late quaternary evolution of the burullus lagoon region north central nile delta egypt abstract the evolution of late quaternary stratigraphic sequences in the burullus lagoon region of the north central nile delta egypt is determined by petrological analysis of radiocarbon dated sediment borings shallow marine lagoonal and fluvial deposits accumulated during the late pleistocene and delta plain to coastal facies during the holocene since about 7500 yrs b p the latter sequence is characterized primarily by an irregular succession of delta plain deposits i e distributary channel fill marsh and lagoon complete coarsening upward sequences formed by prodelta to coastal units and previously defined in the northeastern nile delta are not observed in this region long term sediment accumulation rates for holocene facies during the build up of the delta range from about 100 to 300 cm 1000 yrs the location and ages of three nile distributary channel systems are recognized by means of cores from east to west sebennitic saitic and bolbitine rosetta the mouth of the sebennitic which is oldest of the three was located on what is now the inner to middle shelf this would explain the absence of prodelta and delta front sequences and a presence of a belt of medium to coarse grained sands extending seaward of the coast the distribution in time and space of the holocene facies is interpreted in terms of the interplay of factors controlling sedimentation i e eustatic sea level oscillations climatic changes and land subsidence minor in this region 0 04 cm yr of the three sea level changes dominate paleogeographic maps show through a series of time slices the changing configuration of this region during the past 30 000 years maps indicate the shifting channel systems and the major displacement of associated marshes and lagoons this study suggests that without the emplacement of coastal protection barriers and containment structures an expansion of burullus lagoon may be expected in the near future

land motion estimates from gps at tide gauges a geophysical evaluation summary space geodesy applications have mainly been limited to horizontal deformations due to a number of restrictions on the vertical component accuracy monitoring vertical land motion is nonetheless of crucial interest in observations of long term sea level change or postglacial rebound measurements here we present a global vertical velocity field obtained with more than 200 permanent gps stations most of them colocated with tide gauges tgs we used a state of the art homogeneous processing strategy to ensure that the reference frame was stable throughout the observation period of almost 10 yr we associate realistic uncertainties to our vertical rates taking into account the time correlation noise in the time series the results are compared with two independent geophysical vertical velocity fields 1 vertical velocity estimates using long term tg records and 2 postglacial model predictions from the ice 5g vm2 adjustment the quantitative agreement of the gps vertical velocities with the internal estimates of vertical displacements using the tg record is very good with a mean difference of 0 13 1 64 mm yr 1 on more than 100 sites for 84 per cent of the gps stations considered the vertical velocity is confirmed by the tg estimate to within 2 mm yr 1 the overall agreement with the glacial isostatic adjustment gia model is good with discrepancy patterns related either to a local misfit of the model or to active tectonics for 72 per cent of the sites considered the predictions of the gia model agree with the gps results to within two standard deviations most of the gps velocities showing discrepancies with respect to the predictions of the gia model are however consistent with previously published space geodesy results we in turn confirm the value of 1 8 0 5 mm yr 1 for the 20th century average global sea level rise and conclude that gps is now a robust tool for vertical land motion monitoring which is accurate at least at 1 mm yr 1

statistical approach to earthquake induced landslide susceptibility susceptibility analysis for predicting earthquake induced landslides has most frequently been done using deterministic methods multivariate statistical methods have not previously been applied in this study however we introduce a statistical methodology that uses the intensity of earthquake shaking as a landslide triggering factor this methodology is applied in a study of shallow earthquake induced landslides in central western taiwan the results show that we can accurately interpret landslide distribution in the study area and predict the occurrence of landslides in neighboring regions this susceptibility model is capable of predicting shallow landslides induced during an earthquake scenario with similar range of ground shaking without requiring the use of geotechnical groundwater or failure depth data

assessment of shallow landslide susceptibility by means of multivariate statistical techniques several multivariate statistical analyses have been performed to identify the most influential geological and geomorphological parameters on shallow landsliding and to quantify their relative contribution a data set was first prepared including more than 30 attributes of 230 failed and unfailed slopes the performance of principal component analysis t test and one way test allowed a preliminary selection of the most significant variables which were used as input variables for the discriminant analysis the function obtained has classified successfully 88 5 per cent of the overall slope population and 95 6 per cent of the failed slopes slope gradient watershed area and land use appeared as the most powerful discriminant factors a landslide susceptibility map based on the scores of the discriminant function has been prepared for ensija range in the eastern pyrenees an index of relative landslide density shows that the results of the map are consistent copyright 2001 john wiley sons ltd language en

analyzing successive landslide dam formation by different triggering mechanisms the case of the tangjiawan landslide sichuan china abstract the catastrophic tangjiawan landslide triggered by the 2008 wenchuan earthquake blocked the duba river impounding one of the most dangerous coseismic barrier lakes in beichuan china the lake was drained by an artificial spillway within one month after the earthquake to minimize the potential dam breach flooding risk however on september 5 2016 this landslide was reactivated and dammed the river again creating a 20 m high dam at the same location and resulting in the formation of a barrier lake with a volume of 0 6 million m3 the day after the event we carried out a field investigation of the landslide and obtained a high resolution image and dem using uav the satellite images from 2005 2008 2010 and 2015 were also collected to analyze the evolution of the landslide together with multi temporal dems the geometry and volumes of the displaced mass and the landslide dams and barrier lakes were calculated using image interpretation and 3d spatial analysis with gis this landslide is of great scientific interest as it presents a good example of multiple reactivation of a pre historical giant landslide under different triggering conditions a reactivation of an older landslide during the wenchuan earthquake and a second reactivation during a rainfall event several years later meanwhile from the hazard assessment and prevention perspective it is also representative as it dammed the river twice in 2008 and 2016 posing threats to both upstream and downstream areas we infer that the successive landslides in this region could be caused by the strong tectonic activities including earthquakes and high average uplifting rate the results of landslide volume analysis using multi temporal dems contribute to the landslide mechanism analysis and suggest that the landslide volume estimation is effected by the landslide type landslide rupture surface location and resolution of dem we also compare the performance of different empirical models of landslide stability and dam breach flood parameters and discuss their application during the quick assessment of the potential hazard of the landslide dams generally the successive landslide dams at the tangjiawan site are caused by the successive landslide reactivations on an anti dip slope controlled by strong tectonic activity and river erosion involve with a mass of loose materials of previous landslide deposition and possess high flood risk to the downstream area the experience gained in this work can be used to assist the hazard assessment and the planning of the emergency measures for similar landslide dams in the future

spectroscopic analysis of global tide gauge sea level data summary yearly and monthly tide gauge sea level data from around the globe are fitted to numerically generated tidal data to search for the 18 6 yr lunar nodal tide and 14 month pole tide both tides are clearly evident in the results with amplitudes and phases that are consistent with a global equilibrium response global atmospheric pressure data are fitted to global monthly sea level data to study the response of the ocean to pressure fluctuations the global response of sea level to pressure is found to be inverted barometer at periods greater than 2 months a large coherence at 437 days between pressure and sea level data is found for the north sea baltic sea and the gulf of bothnia the results are not entirely conclusive but they tend to support o connor s 1986 suggestion that the apparent enhanced pole tide in these basins may be due to meteorological forcing rather than to a basin scale resonance finally global averages of tide gauge data after correcting for the effects of post glacial rebound on individual station records reveal an increase in sea level over the last 80 yr of between 1 1 and 1 9 mm yr as part of the process of removing the effects of post glacial rebound we fit those effects to the global tide gauge data and obtain very good agreement with results predicted from post glacial rebound models this tends to support the post glacial model results and it suggests that the global tide gauge data are indeed capable of resolving changes in sea level at the mm yr level

layered internal structure and breaching risk assessment of the higashi takezawa landslide dam in niigata japan the internal structure and geotechnical properties of landslide dams have rarely been examined in detail although they largely control the longevity and potential failure mechanisms of the dams during the 2004 mid niigata prefecture earthquake thousands of landslides were triggered and many landslide dams were formed in the imo river basin among these landslides dams the biggest one that occurred in the higashi takezawa district threatened both the upstream and downstream areas emergency and eventual permanent countermeasures were successfully performed to mitigate the hazards presented by the dam the preserved landslide dam provides a good field study area for improving understanding of the formation and stability of similar features to characterize its internal structure and to provide more reliable information for stability analysis we used a multiple channel surface wave technique and microtremor array measurements to survey the dam s s wave velocity v s profile our results show that the integrated use of these methods is an effective approach for determining the s wave velocity structure of landslide dams irrespective of the mountainous environment in which they typically occur the v s profile suggests that the displaced landslide materials had been little disturbed during movement although movement was rapid and over a long distance we also discuss herein the landsliding mechanism and assess the breaching risk of the landslide dam due to overtopping c 2016 elsevier b v all rights reserved

logistic regression model for predicting the failure probability of a landslide dam landslides may obstruct river flow and result in landslide dams they occur in many regions of the world the formation and disappearance of natural lakes involve a complex earth surface process according to the lessons learned from many historical cases landslide dams usually break down rapidly soon after the formation of the lake regarding hazard mitigation prompt evaluation of the stability of the landslide dam is crucial based on a japanese dataset this study utilized the logistic regression method and the jack knife technique to identify the important geomorphic variables including peak flow or catchment area dam height width and length in sequence affecting the stability of landslide dams the resulting high overall prediction power demonstrates the robustness of the proposed logistic regression models accordingly the failure probability of a landslide dam can also be evaluated based on this approach ten landslide dams formed after the 1999 chi chi earthquake the 2008 wenchuan earthquake and 2009 typhoon morakot with complete dam geometry records were adopted as examples of evaluating the failure probability the stable tsao ling landslide dam which was induced by the chi chi earthquake has a failure probability of 27 68 using a model incorporating the catchment area and dam geometry on the contrary the tangjiashan landslide dam which was artificially breached soon after its formation during the wenchuan earthquake has a failure probability as high as 99 54 typhoon morakot induced the siaolin landslide dam which was breached within one hour after its formation and has a failure probability of 71 09 notably the failure probability of the earthquake induced cases is reduced if the catchment area in the prediction model is replaced by the peak flow of the dammed stream for these cases in contrast the predicted failure probability of the heavy rainfall induced case increases if the high flow rate of the dammed stream is incorporated into the prediction model consequently it is suggested that the prediction model using the peak flow as causative factor should be used to evaluate the stability of a landslide dam if the peak flow is available together with an estimation of the impact of an outburst flood from a landslide dammed lake the failure probability of the landslide dam predicted by the proposed logistic regression model could be useful for evaluating the related risk

contrasting records of sea level change in the eastern and western north atlantic during the last 300 years we present a new 300 year sea level reconstruction from a salt marsh on the isle of wight central english channel uk that we compare to other salt marsh and long tide gauge records to examine spatial and temporal variability in sea level change in the north atlantic our new reconstruction identifies an overall rise in relative sea level rsl of c 0 30 m since the start of the eighteenth century at a rate of 0 9 0 3 mmyr 1 error in variables changepoint analysis indicates that there is no statistically significant deviation from a constant rate within the dataset the reconstruction is broadly comparable to other tide gauge and salt marsh records from the european atlantic demonstrating coherence in sea level in this region over the last 150 300 years in contrast we identify significant differences in the rate and timing of rsl with records from the east coast of north america the absence of a strong late 19th early 20th century rsl acceleration contrasts with that recorded in salt marsh sediments along the eastern usa coastline in particular in a well dated and precise sea level reconstruction from north carolina this suggests that this part of the north carolina sea level record represents a regionally specific sea level acceleration this is significant because the north carolina record has been used as if it were globally representative within semi empirical parameterisations of past and future sea level change we conclude that regional scale differences of sea level change highlight the value of using several regionally representative rsl records when calibrating and testing semi empirical models of sea level against palaeo records this is because by using records that potentially over estimate sea level rise in the past such models risk over estimating sea level rise in the future

the formation and breach of a short lived landslide dam at hsiaolin village taiwan part i post event reconstruction of dam geometry abstract in this paper technologies from multiple disciplines are used to reconstruct the shape of the hsiaolin landslide dam a short lived landslide dam sld that was triggered by typhoon morakot here the formation failure mode and breaching process of this sld are investigated the results indicate that the overtopping time and the debris budget constrained the dam geometry the inferred volume of the hsiaolin landslide dam 15 4 million m3 is much smaller than the actual landslide volume 25 2 million m3 even considering the rock mass dilation and debris entrainment meanwhile a 46 error could be induced if an over simplified equation a function of the dam height length and width is used to calculate the dam volume the saddle of the dam crest which is where overtopping occurred could be used as a reference to measure the dam height and length accordingly the determined dam dimensions of height 44 m length 370 m and width 1500 m are suggested to be the representative geometrical indices that influenced the stability of the hsiaolin landslide dam the flow rate of the dammed river another variable relevant to dam stability was determined from a run off simulation it is suggested that instead of the peak flow before the dam formation the flow rate during the blockage period 2974 m3 s should be used as the training data for building a statistical model for stability predictions finally the low hydraulic gradient at the toe of the dam s surface and the high safety factor of the dam slope indicate that the piping and slope instability were irrelevant to the failure of the hsiaolin short lived landslide dam it is postulated that overtopping about one hour after the blockage dominated the failure process of this heavy rainfall induced landslide dam

development of a foraminifera based transfer function in the basque marshes n spain implications for sea level studies in the bay of biscay abstract in order to reconstruct former sea level we have developed a foraminifera based transfer function using three models based on a modern dataset of 59 samples and 23 species obtained from four basque marshes in northern spain the relationship between observed and foraminifera predicted elevation illustrated the strong performance of the transfer function r 2 jack ranges from 0 74 to 0 81 these results indicated that precise reconstructions of former sea levels are possible error ranges from 0 11 to 0 19 m the transfer function was used to calibrate the foraminiferal assemblages collected from a 50 cm salt marsh core we placed the foraminifera based reconstructions into a temporal framework using 137 cs pb concentrations and 210 pb derived sediment accumulation rates the resulting relative sea level curve is in good agreement with regional tide gauge data both instrumental data and microfossil records suggest a rate of relative sea level rise of approximately 2 mm yr 1 for the 20th century

empirical prediction of coseismic landslide dam formation in this study we develop an empirical method to estimate the volume threshold for predicting coseismic landslide dam formation using landscape parameters obtained from digital elevation models dems we hypothesize that the potential runout and volume of landslides together with river features determine the likelihood of the formation of a landslide dam to develop this method a database was created by randomly selecting 140 damming and 200 non damming landslides from 501 landslide dams and 60 000 landslides induced by the mw 7 9 2008 wenchuan earthquake in china we used this database to parameterize empirical runout models by stepwise multivariate regression we find that factors controlling landslide runout are landslide initiation volume landslide type internal relief h and the h l ratio between h and landslide horizontal distance to river l in order to obtain a first volume threshold for a landslide to reach a river the runout regression equations were converted into inverse volume equations by taking the runout to be the distance to river a second volume threshold above which a landslide is predicted to block a river was determined by the correlation between river width and landslide volume of the known damming landslides the larger of these two thresholds was taken as the final damming threshold this method was applied to several landslide types over a fine geographic grid of assumed initiation points in a selected catchment the overall prediction accuracy was 97 4 and 86 0 for non damming and damming landslides respectively the model was further tested by predicting the damming landslides over the whole region with promising results we conclude that our method is robust and reliable for the wenchuan event in combination with pre event landslide susceptibility and frequency size assessments it can be used to predict likely damming locations of future coseismic landslides thereby helping to plan emergency response copyright 2014 john wiley sons ltd

experiments in reconstructing twentieth century sea levels abstract one approach to reconstructing historical sea level from the relatively sparse tide gauge network is to employ empirical orthogonal functions eofs as interpolatory spatial basis functions the eofs are determined from independent global data generally sea surface heights from either satellite altimetry or a numerical ocean model the problem is revisited here for sea level since 1900 a new approach to handling the tide gauge datum problem by direct solution offers possible advantages over the method of integrating sea level differences with the potential of eventually adjusting datums into the global terrestrial reference frame the resulting time series of global mean sea levels appears fairly insensitive to the adopted set of eofs in contrast charts of regional sea level anomalies and trends are very sensitive to the adopted set of eofs especially for the sparser network of gauges in the early 20th century the reconstructions appear especially suspect before 1950 in the tropical pacific while this limits some applications of the sea level reconstructions the sensitivity does appear adequately captured by formal uncertainties all our solutions show regional trends over the past five decades to be fairly uniform throughout the global ocean in contrast to trends observed over the shorter altimeter era consistent with several previous estimates the global sea level rise since 1900 is 1 70 0 26 mm yr 1 the global trend since 1995 exceeds 3 mm yr 1 which is consistent with altimeter measurements but this large trend was possibly also reached between 1935 and 1950

nile river sediment fluctuations over the past 7000 yr and their key role in sapropel development the provenance pattern of nile river sediments can be used as a proxy for paleoclimatic changes in east africa the 87sr 86sr ratios are particularly appropriate for such provenance investigations because the white nile drains predominantly crystalline basement rocks whereas the blue nile and atbara flow off the ethiopian highlands which consist of tertiary volcanic rocks a high resolution profile of 87sr 86sr and ti al ratios from a well dated core in the nile delta shows a close correspondence with known changes in nile flow over the past 7000 yr at times of higher river flow there was markedly decreased input of blue nile derived and total sediment this change was caused by northward movement of the inter tropical convergence zone resulting in increased vegetative cover in the ethiopian highlands due to higher rainfall and a longer wet season this inverse relationship between nile river flow and sediment flux may have had important implications in the development of agricultural technology in ancient egypt the marked minimum in 87sr 86sr at 4200 4500 yr b p is coincident with the end of the old kingdom in egypt and provides independent evidence that demise of the old kingdom might have been associated with an extended period of catastrophic low floods during the quaternary and late neogene there was periodic deposition of organic rich sediments sapropels in the eastern mediterranean that represent important indicators of major environmental change evidence from the ti al ratio suggests that the pattern of erosion and sediment supply from the nile catchment observed in this study also occurred throughout much of the neogene and quaternary the reduced inputs of blue nile sediment during times of sapropel formation contributed to the increased primary productivity by reducing the amount of phosphate removed on particles and to the observed change to n limitation in the eastern mediterranean which are important characteristics of sapropel deposition

middle east coastal ecosystem response to middle to late holocene abrupt climate changes the holocene vegetation history of the northern coastal arabian peninsula is of long standing interest as this mediterranean semiarid arid region is known to be particularly sensitive to climatic changes detailed palynological data from an 800 cm alluvial sequence cored in the jableh plain in northwest syria have been used to reconstruct the vegetation dynamics in the coastal lowlands and the nearby jabal an nusayriyah mountains for the period 2150 to 550 b c corresponding with the 4 2 to 3 9 and 3 5 to 2 5 cal kyr bp abrupt climate changes accs two large scale shifts to a more arid climate have been recorded these two accs had different impacts on the vegetation assemblages in coastal syria the 3 5 to 2 5 cal kyr bp acc is drier and lasted longer than the 4 2 to 3 9 cal kyr bp acc and is characterized by the development of a warm steppe pollen derived biome 1100 800 b c and a peak of hot desert pollen derived biome at 900 b c the 4 2 to 3 9 cal kyr bp acc is characterized by a xerophytic woods and shrubs pollen derived biome ca 2050 b c the impact of the 3 5 to 2 5 cal kyr bp acc on human occupation and cultural development is important along the syrian coast with the destruction of ugarit and the collapse of the ugarit kingdom at ca 1190 to 1185 b c

stability of landslide dams and development of knickpoints the wenchuan earthquake triggered many landslides and numerous avalanches and created 100 odd quake lakes the quake lakes may be removed or preserved the removal strategy was applied to several large landslide dams which were dangerous because massive amounts of water pooled up in the quake lakes the dams could eventually fail under the action of dam outburst flooding potentially endangering the lives of people in the downstream reaches this paper studied the stability of landslide dams and the development of knickpoints by field investigations and experiments and analyzing satellite images the study concluded that if landslide dams were preserved they would develop into knickpoints and act as a primary control of riverbed incision and thus reduce the potential of new landslide the stability of landslide dams depends mainly on the development of the step pool system and stream power of the flood flow if a landslide dam consists of many boulders a step pool system may develop on the spillway channel of the dam which would maximize the resistance consume most of the flow energy and consequently protect the dam from incision the development degree of the step pool system is represented by a parameter s p which was measured with a specially designed instrument a preservation ratio of landslide dams is defined as the ratio of preserved height after flood scouring to the original height of the dam for streams with peak flood discharge lower than 30 m3 s the preservation ratio is linearly proportional to s p for rivers with a peak flood discharge higher than 30 m3 s 30 30 000 m3 s the minimum s p value for stable channel increases with log p in which p is the unit stream power for a landslide dam with a poorly developed step pool system s p is smaller than the minimum value and the outburst flood incises the spillway channel and causes failure of the dam for preserved landslide dams sediment deposits in the quake lakes a landslide dam may develop into a knickpoint if it is stabilized by long term action of the flow large knickpoints can totally change the fluvial processes and river morphology uplift of the qinghai tibetan plateau has caused extensive channel bed incision along almost all rivers for many rivers the incision has been partly controlled by knickpoints upstream reaches of a knickpoint have a new and unchanging base level this brings about a transition from degradation to aggradation and from vertical bed evolution to horizontal fluvial process multiple and unstable channels are prominent in the reaches upstream of the knickpoints if hundreds of landslide dams occurred simultaneously on a reach of a mountain river the potential energy of bank failure and the slope erosion would be greatly reduced and sediment yield from the watershed may be reduced to nearly zero the quake lakes may be preserved long term and become beautiful landscapes streams with long term unfilled quake lakes have good aquatic ecology

geomorphic hazard assessment of landslide dams in south westland new zealand fundamental problems and approaches abstract quantitative assessments of landslide hazard usually employ empirical heuristic deterministic or statistical methods to derive estimates of magnitude frequency distributions of landsliding the formation and failure of landslide dams are common geomorphic processes in mountain regions throughout the world causing a series of consequential off site hazards such as catastrophic outburst floods debris flows backwater ponding up and downstream aggradation and channel instability conceptual and methodological problems of quantifying geomorphic hazard from landslide dams result from a aspects of defining landslide dam magnitude b scaling effects i e the geomorphic long range and long term implications of river blockage and c paucity of empirical data geomorphic hazard from a landslide dam break flood on the basis of conditional probabilities is being analysed for the alpine south westland region of new zealand where formation and failure of landslide dams is frequent quantification of the annual probability of landsliding and subsequent dam formation in the area is limited by historical and only partially representative empirical data on slope instability since landslide dam stability is a major control governing the potential of catastrophic outburst flooding the ensuing hazard is best assessed on a recurring basis gis based modelling of virtual landslide dams is a simple and cost effective approach to approximate site specific landslide dam and lake dimensions reservoir infill times and scaled magnitude of potential outburst floods although crude these order of magnitude results provide information critical to natural hazard planning mitigation or emergency management decisions

geomorphometric characteristics of new zealand landslide dams abstract this study presents results from a quantitative analysis of a new inventory of n 232 landslide dam occurrences in new zealand previously published data were expanded by documentation of recent events and evidence from a regional air photo reconnaissance focused on the upland regions of southwestern south island additional geomorphometric data on landslide dams associated lakes and contributing catchment characteristics were extracted from a 25 m digital elevation model dem augmented by limited ground truthing and compiled in a gis based inventory the new zealand case examples fall into the global trend although they contain both two extremely large features in terms of landslide dam volume vd and lake volume vl analysis suggests that landslide dam height hd landslide dam volume vd lake volume vl contributing catchment area ac and local relief hr are key variables for assessing landslide dam stability independently from other catchment parameters such as lithology climate or dam sedimentology they may be provisionally used as representative characteristics of landslide dams irrespective of environmental boundary conditions such as climate geology or site specific valley geomorphometry three newly proposed dimensionless indices i e the backstow index is basin index ia and relief index ir based on landslide dam height hd allow limited yet promising preliminary assessments of landslide dam stability compared with worldwide examples they also demonstrate a much narrower conditional range for the formation of stable landslide dams in new zealand catchment parameters such as maximum elevation emax upstream relief hr contributing catchment area ac and relief ratio rr are significantly different at sites of former and existing landslide dammed lakes and may be used as independent variables in future terrain based classification schemes generally data are incomplete with underreporting of small and ephemeral landslide dams and over representation of earthquake case studies nonparametric correlation highlights the statistical interdependence between geomorphometric variables as an artefact of initial data calculation while varying accuracy poses a significant drawback for complex multivariate statistical techniques such as principal component cluster or discriminant analyses

assessing the internal structure of landslide dams subject to possible piping erosion by means of microtremor chain array and self potential surveys abstract an integrated geophysical approach comprising microtremor chain array and self potential surveys was used to assess the internal structure of landslide dams subject to possible piping erosion in selected sites in japan and kyrgyzstan the non invasive geophysical approach is cost effective environmentally friendly and portable and hence it has proven to be valuable for the geotechnical assessment of landslide dams where piping can trigger failure of the dam while the microtremor chain array survey results revealed the internal structure of the landslide dam the self potential survey results indicated the path of anomalous seepage zones in the surveyed sites of long existing landslide dams the presence of a seepage path in the dam was confirmed by a good correlation between the areas of low phase velocity and large negative self potential anomalies in summary this integrated geophysical approach could be useful for the early risk assessment of landslide dams and prediction of landslide dam failure by piping

comparing models of debris flow susceptibility in the alpine environment abstract debris flows are widespread in val di fassa trento province eastern italian alps where they constitute one of the most dangerous gravity induced surface processes from a large set of environmental characteristics and a detailed inventory of debris flows we developed five models to predict location of debris flow source areas the models differ in approach statistical vs physically based and type of terrain unit of reference slope unit vs grid cell in the statistical models a mix of several environmental factors classified areas with different debris flow susceptibility however the factors that exert a strong discriminant power reduce to conditions of high slope gradient pasture or no vegetation cover availability of detrital material and active erosional processes since slope and land use are also used in the physically based approach all model results are largely controlled by the same leading variables overlaying susceptibility maps produced by the different methods statistical vs physically based for the same terrain unit of reference grid cell reveals a large difference nearly 25 spatial mismatch the spatial discrepancy exceeds 30 for susceptibility maps generated by the same method discriminant analysis but different terrain units slope unit vs grid cell the size of the terrain unit also led to different susceptibility maps almost 20 spatial mismatch maps based on different statistical tools discriminant analysis vs logistic regression differed least less than 10 hence method and terrain unit proved to be equally important in mapping susceptibility model performance was evaluated from the percentages of terrain units that each model correctly classifies the number of debris flow falling within the area classified as unstable by each model and through the metric of roc curves although all techniques implemented yielded results essentially comparable the discriminant model based on the partition of the study area into small slope units may constitute the most suitable approach to regional debris flow assessment in the alpine environment

sea level changes at tenerife island ne tropical atlantic since 1927 hourly sea level observations measured by five tide gauges at santa cruz harbor tenerife island in the northeastern tropical atlantic have been merged to build a consistent and almost continuous sea level record starting in 1927 datum continuity was ensured using high precision leveling information the time series underwent a detailed quality control in order to remove outliers time drifts and datum shifts the resulting sea level record was then used to describe the low frequency interannual to decadal sea level variability at tenerife it was found that at interannual and longer time scales the observed sea level changes are primarily driven by steric sea level variations such steric changes are originated by coastal trapped waves induced by longshore winds along the continental coast and propagate poleward observed sea level rise at tenerife was 2 09 0 04 mm yr since 1927 according to the hydrographic observations in the area only half of this trend was attributed to steric sea level changes for the top 500 m at least since 1950

oil source correlation in the slope of the qikou depression in the bohai bay basin with discriminant analysis abstract the commonly used tools for oil source correlation such as mass chromatograms of biomarkers and bivariate cross plots of geochemical parameters cannot deal with multiple geochemical parameters and plenty of samples simultaneously leading to uncertainties in the results and even failures sometimes in this paper the discriminant analysis da is selected from supervised machine learning algorithms as it is superior to the commonly used tools as well as other multivariate statistical methods with the accumulation of geochemical data of source rocks and oils in the slope of the qikou depression the main source rocks in the third es3 and first members es1 of the paleogene shahejie formation were deposited in similar depositional environments the source rocks cannot be distinguished with the commonly used tools we firstly extended geochemical parameters and then used stepwise da to select informative parameters and to develop a discriminant model for oil source correlation the 22 selected parameters are supported by geochemical characteristics of the source rocks in the study area the da of these parameters for oil source correlation achieved a high correct rate of original validation 96 8 and leave one out cross validation 89 4 indicating a sufficient discriminatory power the oil source correlation results with high posterior probabilities showing strong similarity between the sources and oils coincide with geological conditions and illustrate that there is still much exploration potential in the study area especially for the es3 petroleum system all these illustrate that da is one of the most useful tools for oil source correlation with the accumulation of geochemical data of source rocks and oils

the formation and impact of landslide dams state of the art abstract the blocking of river courses by mass movements is very common in mountainous areas with deep and narrow valleys landslide dams may pose serious threats to people and their livelihoods downstream in the case of abrupt dam failure since the publication of benchmark reviews of costa and schuster 1988 and korup 2002 there is a growing number of studies focusing on the formation stability and short term impacts of landslide dams this review combines the insights of all these studies builds on current concepts of landslide dams and suggests ways to unify terminologies and classifications we furthermore present a new worldwide database compiled from literature data it contains 410 landslide dams 1 million m3 in volume that were formed since 1900 since these have the most complete data entries these data show that dam longevity is among other factors correlated with the type of landslide forming the dam those formed by rock debris avalanches and rockslides have longest lifespans however the influence of landslide type or material on dam longevity decreases with time after dam formation to ensure consistency in the next database generation we suggest guidelines for data collection to provide a solid basis for evaluating dam stability and governing factors a preliminary classification matrix for landslide dam stability that combines topographic setting and the internal structure of the dam body is another outcome of our review furthermore an evaluation of the various geomorphic stability indices proposed in the literature regarding their suitability and limitations in assessing dam formation and stability shows that they predict the probability of dam formation reasonably well but that their application to longevity estimates requires further assessment the geomorphic impacts of landslide dams in the short medium and long term are summarized and illustrated with key examples finally for a better understanding of the factors controlling dam stability we recommend to 1 include dam composition and sedimentary structures in future case studies 2 maintain and update the worldwide database for sound statistical analyses 3 refine landslide dam stability indices and test them for different landslide types and 4 study hazard cascades related to multiple dams in one watershed for long term landscape evolution studies we suggest to 5 quantify terrestrial sediment flux related to landslide dams 6 detect ancient landslide dams in river profiles and 7 further exploit the sediment archives in former impoundment areas

global sea level trend in the past century data derived from tide gauge stations throughout the world indicate that the mean sea level rose by about 12 centimeters in the past century the sea level change has a high correlation with the trend of global surface air temperature a large part of the sea level rise can be accounted for in terms of the thermal expansion of the upper layers of the ocean the results also represent weak indirect evidence for a net melting of the continental ice sheets

combining spectral and geoenvironmental information for probabilistic event landslide mapping abstract landslide mapping is important for emergency management and landslide risk assessment in this study we propose a new mapping method which combines the spectral signal contained in a satellite image and the geoenvironmental information included in a landslide susceptibility map the image analysis captures areas with spectral signatures of event landslides in the image while the landslide susceptibility map filters sub areas which do not have landslide prone conditions the method assigns to every pixel of the satellite image a combined probability of landslide presence we mapped typhoon triggered landslides in southern taiwan using the method to compare with a landslide inventory prepared from orthophotos we converted the probability map to a binary map of landslides and landslide free areas map comparison resulted in an overall accuracy of 0 93 an area percentage of overlapped landslides of 0 84 a modified success rate of 0 89 and a kappa statistic of 0 73 the method is fast flexible and relatively easy to use and the probability map the method produces is useful by itself we expect that the method can facilitate the rapid production of event landslide inventory maps which in turn can assist emergency management

observed mean sea level changes around the north sea coastline from 1800 to present this paper assesses historic changes in mean sea level around the coastline of the north sea one of the most densely populated coasts in the world typically such analyses have been conducted at a national level and detailed geographically wider analyses have not been undertaken for about 20 years we analyse long records up to 200 years from 30 tide gauge sites which are reasonably uniformly distributed along the coastline and 1 calculate relative sea level trends 2 examine the inter annual and decadal variations 3 estimate regional geocentric sometimes also referred to as absolute sea level rise throughout the 20th century and 4 assess the evidence for regional acceleration of sea level rise relative sea level changes are broadly consistent with known vertical land movement patterns the inter annual and decadal variability is partly coherent across the region but with some differences between the inner north sea and the english channel data sets from various sources are used to provide estimates of the geocentric sea level changes the long term geocentric mean sea level trend for the 1900 to 2011 period is estimated to be 1 5 0 1 mm yr for the entire north sea region the trend is slightly higher for the inner north sea i e 1 6 0 1 mm yr and smaller but not significantly different on the 95 confidence level for the english channel i e 1 2 0 1 mm yr the uncertainties in the estimates of vertical land movement rates are still large and the results from a broad range of approaches for determining these rates are not consistent periods of sea level rise acceleration are detected at different times throughout the last 200 years and are to some extent related to air pressure variations the recent rates of sea level rise i e over the last two to three decades are high compared to the long term average but are comparable to those which have been observed at other times in the late 19th and 20th century

late quaternary palaeoclimatic oscillations in east africa recorded by heavy minerals in the nile delta because the nile carries a load derived from markedly different geological terrains and climatic zones it is expected that minera logical study of deposits in its delta could help define changes in palaeoclimate affecting east africa here we report measurements on heavy minerals in the nile delta which can be used as distinct markers of climatic shifts over africa during the late pleistocene to recent variations of heavy minerals in radiocarbon dated cores collected in this delta1 the nile s major depocentre2 correlate closely with oscillations in african palaeoclimate determined by other independent methods such as studies of lake levels these variations are largely a function of the characteristics of the nile it flows across nearly 35 of latitude from south of the equator to the mediterranean fig la and conditions in its drainage basin which includes central africa the ethiopian plateau and eastern sahara range from a tropical humid to a warm arid climate east african climatic belts migrated considerably during the quaternary3 5 modifying nile discharge and sediment load climatic oscillations have been recorded by changes of sediment yield and grain size along its course6 7 and by well defined depositional cycles8 including sapropels9 in the eastern mediterranean

a 20th century acceleration in global sea level rise 1 multi century sea level records and climate models indicate an acceleration of sea level rise but no 20th century acceleration has previously been detected a reconstruction of global sea level using tide gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea level rise but no significant acceleration over this period here we extend the reconstruction of global mean sea level back to 1870 and find a sea level rise from january 1870 to december 2004 of 195 mm a 20th century rate of sea level rise of 1 7 0 3 mm yr 1 and a significant acceleration of sea level rise of 0 013 0 006 mm yr 2 this acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed if this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm consistent with projections in the ipcc tar

forecasting landslide hazard by the 3d discrete element method a case study of the unstable slope in the lushan hot spring district central taiwan abstract catastrophic landslides and related phenomena are commonly facilitated by the subtropical climate with frequent typhoons and recurrent earthquakes in taiwan s mountainous areas one area susceptible to potentially catastrophic landslides is located at lushan in central taiwan which is famous for its hot springs and tourism the northern slope above the hot spring district slips gradually and frequently due to heavy rainfall for safety reasons the slip affected area has been under constant borehole monitoring by government agencies and a controversial public debate has arisen over permanent evacuation of the hot spring district in this study we attempt to simulate possible scenarios of catastrophic slope failure using slip geometries derived from the monitoring data and assess potential landslide impact areas by a discrete element method using the pfc3d code in the worst case scenario the lushan hot spring district is predicted to be destroyed by debris in 20 s besides the planned regional emergency refuge is rapidly jeopardized by flooding resulted from landslide dammed lakes this study addresses catastrophic slope failure under heavy rainfall conditions given a range of friction coefficients and varied continuity of the failure surfaces it is noted that the pfc3d code has limitations in modeling all complex mechanisms of landslide particularly in modeling loss of material shear strength due to increases in pore pressure nevertheless the numerical simulation results by the 3d discrete element method provide scenario based runout paths particle velocities and landslide affected areas which are useful information for decision support and future landslide hazard assessment

climate change and the collapse of the akkadian empire evidence from the deep sea the akkadian empire ruled mesopotamia from the headwaters of the tigris euphrates rivers to the persian gulf during the late third millennium b c archeological evidence has shown that this highly developed civilization collapsed abruptly near 4170 150 calendar yr b p perhaps related to a shift to more arid conditions detailed paleoclimate records to test this assertion from mesopotamia are rare but changes in regional aridity are preserved in adjacent ocean basins we document holocene changes in regional aridity using mineralogic and geochemical analyses of a marine sediment core from the gulf of oman which is directly downwind of mesopotamian dust source areas and archeological sites our results document a very abrupt increase in eolian dust and mesopotamian aridity accelerator mass spectrometer radiocarbon dated to 4025 125 calendar yr b p which persisted for 300 yr radiogenic nd and sr isotope analyses confirm that the observed increase in mineral dust was derived from mesopotamian source areas geochemical correlation of volcanic ash shards between the archeological site and marine sediment record establishes a direct temporal link between mesopotamian aridification and social collapse implicating a sudden shift to more arid conditions as a key factor contributing to the collapse of the akkadian empire

sea level changes since the last glacial maximum an appraisal of the ipcc fourth assessment report the ipcc fourth assessment report ar4 stated that global sea level rose by about 120 m between the last glacial maximum lgm and 3 2 ka and did not rise again until the late 19th century a review of relevant literature demonstrates that the rise may have been larger by 10 15 m that the timing of stabilisation is poorly constrained within the last 7 ka bp and that the onset of modern rates of sea level rise is not synchronous and uniform across the globe the lgm lowstand as defined in the ar4 is based on the classic barbados sea level history but the sea level curve from this island may not be an accurate eustatic approximation if glacial isostatic adjustment gia processes were significant as suggested by various authors the barbados sea level curve revealed the existence of meltwater pulse mwp 1a at around 14 000 cal a bp questions about the source and causal mechanism of mwp 1a are still being explored by field scientists and gia modellers these problems have direct relevance for contemporary measurements of ice mass changes because space geodetic measurements rely on information provided by gia models to separate land motion from ice mass changes global patterns of holocene sea level change are controlled by regional sea level variability not only through isostatic and tectonic processes but also through steric effects longer wavelength gravitational changes produced by changing ice ocean mass flux and hemispheric scale perturbations in the earth s rotation eustasy is therefore merely a concept not a measurable quantity constraining the late holocene ice melt contribution to global sea level rise and determining regional sea level rise patterns in the 18th and 19th centuries are important future tasks for sea level scientists these will establish the baseline contributions to 20th and 21st century sea level rise and will help to determine the causes of modern rates of sea level rise constraining historical sea level accelerations and short term ice mass flux will aid models of ice sheet dynamics and help to reduce current uncertainties in future sea level predictions the ar4 shows that regional sea level variability is clearly present in sea level change patterns for the past 50 a and an important challenge for the next ipcc assessment is to incorporate this variability into regional future sea level rise scenarios copyright 2009 john wiley sons ltd

holocene climate and cultural evolution in late prehistoric early historic west asia abstract the precipitation climatology and the underlying climate mechanisms of the eastern mediterranean west asia and the indian subcontinent are reviewed with emphasis on upper and middle tropospheric flow in the subtropics and its steering of precipitation holocene climate change of the region is summarized from proxy records the indian monsoon weakened during the holocene over its northernmost region the ganges and indus catchments and the western arabian sea southern regions the indian peninsula do not show a reduction but an increase of summer monsoon rain across the holocene the long term trend towards drier conditions in the eastern mediterranean can be linked to a regionally complex monsoon evolution abrupt climate change events such as the widespread droughts around 8200 5200 and 4200 cal yr bp are suggested to be the result of altered subtropical upper level flow over the eastern mediterranean and asia the abrupt climate change events of the holocene radically altered precipitation fundamental for cereal agriculture across the expanse of late prehistoric early historic cultures known from the archaeological record in these regions social adaptations to reduced agro production in both dry farming and irrigation agriculture regions are visible in the archaeological record during each abrupt climate change event in west asia chronological refinement in both the paleoclimate and archaeological records and transfer functions for both precipitation and agro production are needed to understand precisely the evident causal linkages

is land subsidence increasing the exposure to sea level rise in alexandria egypt delta margins are subject to relatively high rates of land subsidence and have the potential to significantly exacerbate future changes in sea levels predicted by global warming models used in impact studies through a combined analysis of gps and persistent scatterer interferometry data we determine that most of the coastline of alexandria has been subject to moderate land subsidence over the past decade 0 4 mm yr on average and up to 2 mm yr locally this contrasts to previous studies that suggested subsidence in excess of 3 mm yr based on our findings we infer that on multi century to millennia timescales land subsidence in the area of alexandria is dominated by tectonic setting and earthquakes or gravitational collapse episodes of a growth fault whereas on shorter interseismic decadal to century timescales subsidence rates are likely steady and moderate in agreement with natural compaction and dewatering of the observed holocene sediment layer

vertical land motion and relative sea level changes along the coastline of brest france from combined space borne geodetic methods abstract in spite of the recent advances and the current perspectives of satellite radar altimetry to reach the coastline and monitor coastal sea level changes this space borne technology remains geocentric by essence in contrast the quantity that matters for coastal management and society is relative sea level that is the sea level relative to the land as measured by conventional tide gauges however two important issues are associated with the use of tide gauges first supplemental information is required to separate vertical land motion from ocean climate signals in tide gauge records and hence to understand the causes of future coastal sea level changes and their relative importance this can be provided by space borne geodetic techniques for instance installing a permanent global positioning system gps antenna at the tide gauge second vertical land motion can show local spatial patterns which limits the spatial validity of the point wise information at the gps station using interferometry synthetic aperture radar insar and high precision gps data the above mentioned limitations were addressed in the case study of brest france our findings show that over the past decades brest and its surroundings are overall stable in agreement with the geological setting except for the embankment areas of the commercial and military harbours the gps calibrated insar results were then further combined with geocentric satellite radar altimetry data to obtain relative sea level trends along the brest coastline with an unprecedented high spatial resolution of 200 m our approach is applicable beyond the case study of brest especially in coastal areas where tide gauge data are not available provided satellite data are

rates and causes of recent global sea level rise inferred from long tide gauge data records abstract tide gauge data at seven sites of the permanent service for mean sea level psmsl with information for relative sea level during the past 140 200 yr were analyzed to examine the rates and causes of the global sea level rise gslr during the twentieth century by subtracting linear trends for relative sea level rise during the past 100 yr from the observed data we get the apparent gslrs of 1 mm yr 1 for five sites around the baltic sea and brest the rate for san francisco is significantly larger than this with an optimum value 2 mm yr 1 the spatial difference of 1 mm yr 1 between these sites is reasonably explained by the recent melting of the greenland ice sheet with an equivalent sea level rise of 1 mm yr 1 the predicted relative sea level change for this melting scenario is 0 5 mm yr 1 at sites around the baltic sea and brest and 1 5 mm yr 1 for san francisco the residuals between observations and predictions 0 5 mm yr 1 at all sites may be contributed by thermal expansion of seawater and or other melting sources these results suggest the rate of twentieth century gslr to be 1 5 mm yr 1

are long tide gauge records in the wrong place to measure global mean sea level rise ocean dynamics land motion and changes in earth s gravitational and rotational fields cause local sea level change to deviate from the rate of global mean sea level rise here we use observations and simulations of spatial structure in sea level change to estimate the likelihood that these processes cause sea level trends in the longest and highest quality tide gauge records to be systematically biased relative to the true global mean rate the analyzed records have an average twentieth century rate of approximately 1 6 mm yr but based on the locations of these gauges we show that the simple average underestimates the twentieth century global mean rate by 0 1 0 2 mm yr given the distribution of potential sampling biases we find that 1 probability that observed trends from the longest and highest quality tide gauge records are consistent with global mean rates less than 1 4 mm yr

simulation of the parma river blockage by the corniglio landslide northern italy abstract near the village of corniglio in the northern apennines about 40 km sw of parma a big landslide was recently 1994 1996 subjected to reactivation damaging many buildings and partially obstructing the parma river in this work we have carried out a quantitative analysis of the recent evolution of the landslide with the help of a geographic information system gis in order to predict the most plausible future developments then various simulations of landslide descent were carried out and above all to evaluate the possibility of blockage formation to this purpose two computer programs that simulate the material descent through a cellular automata model and define blockage characteristics were written many different simulations were carried out 16 of which are presented here for each of them the computer output consists of a table defining the quantity of displaced material area and volume of the dam and lake and of a map showing the areas involved in the landslide movement and upstream flooding in order to assess the probability of blockage formation and dam stability we applied the simulation results to some empirical rules defined by preceding authors through statistical analysis carried out on a high number of analogous phenomena these rules suggest that it is very unlikely that blockage takes place as the result of very slow landslide velocity riverbed width and high erodibility of the material if it were to occur the size and shape of the dam seem sufficient to guarantee a considerable degree of stability making a sudden failure improbable

tide gauge datum continuity at brest since 1711 france s longest sea level record the issue of a possible tide gauge datum discontinuity at brest caused by the bombing of the city in august 1944 is discussed this issue is very important as many scientists have used this long record to derive a long term sea level trend estimate for use within global sea level rise studies a detailed analysis of historical leveling information and comparison of sea level data between adjacent stations proved to be worthwhile even beyond this initial scope of the study it led to an accurate datum connection between recently rediscovered 18th century sea level data back to 1711 and those of the present day the study provides additional evidence that the onset of recent rapid sea level rise most likely took place in the late 19th century in agreement with the nearby liverpool sea level record and with independent results from sediment cores collected in salt marshes located in both hemispheres

geological and morphological study of the jiufengershan landslide triggered by the chi chi taiwan earthquake the jiufengershan rock and soil avalanche is one of the largest landslides triggered by the chi chi earthquake taiwan 1999 the landslide destabilized the western limb of the taanshan syncline along a weak stratigraphic layer it involved a flatiron remnant which was almost entirely mobilized during the earthquake the avalanche was slowed down by ns trending ridges located downstream along the jiutsaihu creek the landslide affected a 60 m thick and 1 5 km long sedimentary pile composed of shales and sandstones which dip 228se toward a transverse valley the triggering mechanism and the sliding process were analyzed by means of geological and morphological data from aerial photographs and observed in the field a high resolution airborne light detection and ranging lidar image taken 2 5 years after the landslide allows the identification of morphological structures along the sliding surface and the landslide accumulation the sliding surface shows several deformation structures such as fault scarps and folds these structures are interpreted in terms of basal shear stresses created during the avalanche three major joint sets were identified at the sliding surface the isopach map of the landslide was calculated from the comparison between elevation models before and after the earthquake the coseismic volume of mobilized material and landslide deposit data are 4210 6 m 3 and 5010 6 m 3 respectively the geometry of the landslide accumulation in the field has an irregular star shape the morphology of the deposit area shows a sequence of smooth reliefs and depressions that contrast with the neighboring ridges d 2005 elsevier b v all rights reserved

influence of textural properties on the failure mode and process of landslide dams abstract the failure of a landslide dam is a sudden geo hazard which can significantly threatens the lives and property of local residents in this study 11 experiments were designed to reproduce the failure process of landslide dams with different grain size distributions and hydrodynamic conditions in order to fully consider the influence of seepage on the stability of landslide dams with different textural properties the inflow discharge was small in these tests by analyzing the experimental data we found that the textural properties plays a key role in the failure modes and process of landslide dams the eleven tests produced five different results the landslide dam in experiment 1 and 8 remained stable the landslide dam in experiment 2 partially failed in experiments 3 6 the dams failed due to overtopping and erosion while in experiment 7 the dam failed due to overtopping and soil collapse in experiment 9 11 the dams failed due to piping overtopping and erosion in addition the evolution of the outflow discharge and density also varied for the different textural properties of the dam materials based on the experimental results the landslide dam materials were classified as coarse matrix controlled medium particle controlled fine matrix controlled and balanced composition the failure modes and process as well as the evolution characteristics of the outflow discharge and flow density were all summarized providing a scientific reference for disaster prevention and mitigation research of landslide dams

a new holocene relative sea level curve for western brittany france insights on isostatic dynamics along the atlantic coasts of north western europe abstract this study presents new relative sea level rsl data that were obtained in the finistere region western tip of brittany france and the implications those data have for the understanding of the isostatic dynamics across north western europe and more specifically along the atlantic and channel coasts new stratigraphic sequences were obtained and analyzed to derive 24 new sea level index points in which 6 are basal these new data considerably increase the knowledge we have of the rsl evolution along the coasts of western brittany since the last 8 kyr b p from this new dataset rsl was estimated to rise continuously over the last 8 kyr with a major inflection at ca 6 kyr cal bp our results show large vertical discrepancies between the rsl records of brittany and south western uk with the latter plotting several meters below the new data from this comparison we suggest that the two regions underwent a very different pattern and or amplitude of subsidence during the last 8 kyr which has implications for the spatial and temporal pattern of the peripheral bulge of the european ice sheets we compared our data against predictions from glacio isostatic adjustment models gia models there are large misfits between rsl observations and the predictions of the global ice 5g vm2a peltier 2004 glac1 b tarasov and peltier 2002 tarasov et al 2012 briggs et al 2014 and regional uk models biis bradley et al 2009 bradley et al 2011 kuchar kuchar et al 2012 which can t be resolved through significant changes to the deglaciation history and size of the british irish ice sheet paleo tidal modelling corrections indicate regional changes in the tidal ranges played a negligible role in the data model misfits hence we propose that the misfits are due to some combination of i unaccounted mass loss of far field ice sheets antarctic ice sheet or laurentide ice sheet ii unresolved differences in the deglaciation history and size of the fennoscandian ice sheet or more likely iii significant lateral variations in the earth s structure across the english channel

mediterranean quaternary sapropels an immediate response of the african monsoon to variation of insolation abstract in the subsurface of the east mediterranean sea eleven discrete basin wide organic rich black sapropels were deposited during the last 465 000 years they are dated by oxygen isotopic chronostratigraphy the most recent sapropel has been shown to be the consequence of heavy nile river summer floods due to increased monsoonal summer precipitation over ethiopia and not of scandinavian ice sheet meltwater influx into the east mediterranean sea as was previously believed while most sapropels were deposited during interglacials two thick sapropels formed during glacial periods as shown by their position in the oxygen isotopic stratigraphy and by their pollen record in core rc9 181 the new evidence presented here is that the sapropel sequence in this core including the two glacial sapropels correlates on a one to one basis with the highest values of an index of insolation on top of the atmosphere the concept of this index derives from an analysis of the african monsoon process the index variation is computed for the last 465 000 years from the caloric northern summer insolation in the tropical latitudes controlled by variations of the earth s orbital parameters it is conjectured that this index might be linked through the climate system to the monsoonal precipitation which in africa produces the nile river summer flood

nile delta vegetation response to holocene climate variability a 7000 yr palynologic record from burullus lagoon nile delta egypt is assessed to investigate changes in terrestrial vegetation in response to nile flow previous studies in this region have shown that sea level rise in the early to mid holocene and markedly increased human land use during the past several centuries altered vegetation in and around the lagoon the pollen record from this study documents changes in delta vegetation that likely reflect variations in nile flow we suggest that cyperaceae pollen is a sensitive marker of precipitation over the nile headwaters and the resultant nile flow decreases in cyperaceae pollen interpreted as a marker for diminished nile flow as well as the increase in relative abundance of microscopic charcoal occurred at ca 6000 5500 ca 5000 ca 4200 and ca 3000 cal yr b p calibrated years before present these correspond to extreme regional and global aridity events associated with a more southerly mean position of the intertropical convergence zone these changes also recorded by other proxy studies indicate that several marked regional drought events affected the nile delta region and impacted ancient egyptian and middle eastern civilizations

long term and recent changes in sea level in the falkland islands 1 mean sea level measurements made at port louis in the falkland islands in 1981 1982 1984 and 2009 together with values from the nearby permanent tide gauge at port stanley have been compared to measurements made at port louis in 1842 by james clark ross the long term rate of change of sea level is estimated to have been 0 75 0 35 mm yr between 1842 and the early 1980s after correction for air pressure effects and for vertical land movement due to glacial isostatic adjustment gia the 2009 port louis data set is of particular importance due to the availability of simultaneous information from port stanley the data set has been employed in two ways by providing a short recent estimate of mean sea level itself and by enabling the effective combination of measurements at the two sites the rate of sea level rise observed since 1992 when the modern stanley gauge was installed has been larger at 2 51 0 58 mm yr after correction for air pressure and gia this rate compares to a value of 2 79 0 42 mm yr obtained from satellite altimetry in the region over the same period such a relatively recent acceleration in the rate of sea level rise is consistent with findings from other locations in the southern hemisphere and globally