discharge of debris from ice at the margin of the greenland ice sheet sediment production at a terrestrial section of the ice sheet margin in west greenland is dominated by debris released through the basal ice layer the debris flux through the basal ice at the margin is estimated to be 12 45 m 3 m 1 a 1 this is three orders of magnitude higher than that previously reported for east antarctica an order of magnitude higher than sites reported from in norway iceland and switzerland but an order of magnitude lower than values previously reported from tidewater glaciers in alaska and other high rate environments such as surging glaciers at our site only negligible amounts of debris are released through englacial supraglacial or subglacial sediment transfer glaciofluvial sediment production is highly localized and long sections of the ice sheet margin receive no sediment from glaciofluvial sources these findings differ from those of studies at more temperate glacial settings where glaciofluvial routes are dominant and basal ice contributes only a minor percentage of the debris released at the margin these data on debris flux through the terrestrial margin of an outlet glacier contribute to our limited knowledge of debris production from the greenland ice sheet

abnormal monsoon years and their control on erosion and sediment flux in the high arid northwest himalaya abstract the interplay between topography and indian summer monsoon circulation profoundly controls precipitation distribution sediment transport and river discharge along the southern himalayan mountain front shf the higher himalayas form a major orographic barrier that separates humid sectors to the south and arid regions to the north during the indian summer monsoon vortices transport moisture from the bay of bengal swirl along the shf to the northwest and cause heavy rainfall when colliding with the mountain front in the eastern and central parts of the himalaya precipitation measurements derived from passive microwave analysis ssm i show a strong gradient with high values at medium elevations and extensive penetration of moisture along major river valleys into the orogen the end of the monsoonal conveyer belt is near the sutlej valley in the nw himalaya where precipitation is lower and rainfall maxima move to lower elevations this region thus comprises a climatic transition zone that is very sensitive to changes in indian summer monsoon strength to constrain magnitude temporal and spatial distribution of precipitation we analyzed high resolution passive microwave data from the last decade and identified an abnormal monsoon year amy in 2002 during the 2002 amy violent rainstorms conquered orographic barriers and penetrated far into otherwise arid regions in the northwest himalaya at elevations in excess of 3 km asl while precipitation in these regions was significantly increased and triggered extensive erosional processes i e debris flows on sparsely vegetated steep hillslopes mean rainfall along the low to medium elevations was not significantly greater in magnitude this shift may thus play an important role in the overall sediment flux toward the himalayan foreland using extended precipitation and sediment flux records for the last century we show that these events have a decadal recurrence interval during the present day monsoon circulation hence episodically occurring amys control geomorphic processes primarily in the high elevation arid sectors of the orogen while annual recurring monsoonal rainfall distribution dominates erosion in the low to medium elevation parts along the shf

multiarchive paleoseismic record of late pleistocene and holocene strong earthquakes in switzerland a multiarchive approach has been applied to the investigation of the late pleistocene and holocene record of strong earthquakes in switzerland the geological archives used for this study include active faults lake deposits slope instabilities and caves in the basle area eight trenches were opened across the basle reinach fault nearby rockfall deposits were systematically investigated sediment cores were taken from two lakes and nine caves were studied in central switzerland five lakes were investigated by means of high resolution seismic lines and sediment cores furthermore three caves were studied in central switzerland altogether the investigations are based on more than 350 km of high resolution reflection seismic lines 450 m of core samples 260 m of trenches and 245 radiocarbon age determinations the measured co seismic displacements along the basle reinach fault supply independent information for the magnitude of the ad 1356 basle earthquake exclusively based on geological evidence deformation features related to three well documented strong historic earthquake shocks were identified deformation features of the ad 1774 altdorf and ad 1601 unterwalden earthquakes can be used to calibrate paleoseismic evidence in central switzerland altogether traces of 13 earthquakes could be found in the two study areas all of them with magnitudes mw 6 or greater for the first time the earthquake catalogue for switzerland can be extended back beyond historic records into the late pleistocene spanning 15 000 years d 2005 elsevier b v all rights reserved

spatial distribution analysis of landslides triggered by 2008 5 12 wenchuan earthquake china abstract the 2008 5 12 wenchuan earthquake seismic magnitude mw 7 9 according to the usgs triggered a great number of landslides a spatial database of landslides is built by interpreting the remote sensing rs data which covers 11 counties severely damaged by the earthquake with area of about 31 686 12 km2 the geological settings of the study area are detailed mapped including geologic structure and lithology the digital elevation model dem of the study area with resolution of 30 m 30 m is presented to address the topographic characteristics correlations between the occurrence of landslides with geological settings i e active faults the coseismic surface ruptures geological unit slope gradient slope elevation as well as slope aspect are analyzed using spatial modeling in gis with the aids of field investigations it can be concluded that the distance to the causative faults and slope gradient are much more important than other factors landslides are clustered distributed along the causative faults of f2 and f3 and landslides incidence are dramatically decreasing with the increasing of the distance to the causative faults the landslides incidence has an obvious increase near the active faults i e f1 landslide concentration lc landslides km2 has an obvious exponent increase with slope gradient however lc has no obvious relationship with geological unit and slope elevation the difference of lc value in each geological unit each slope elevation category maybe have been the result affected by slope gradient for each geological unit each slope elevation category and distance of each geological unit each slope elevation category to causative fault zone isoseismal map reflects the incidence of landslides in some degree and lc increases dramatically with intensity increasing almost all landslides occurred in the region above vi degree statistics result also indicates that in the near field of causative faults landslides tend to have the initial sliding direction similar to the movement of the causative faults and preliminary study shows that landslides incidence varies in different slopes with different structure and consequent slopes and obsequent slopes have a higher landslides incidence than other layered slopes

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

early development and flysch sedimentation in ordovician taconic foreland basin west central newfoundland during the early to late ordovician the taconic foredeep in west central newfoundland evolved from an underfilled to an overfilled state in response to cratonward advance thickening and erosion of the taconic orogen early orogen derived sediment in the foreland basin consisted of middle to lake arenigian deep water mudstones that accumulated on an inner craton facing slope prism uppermost parts of shallow bay and green point formations and correlative units these deposits are interbedded with and overlie passive margin slope sediments in the middle arenigian to early llanvirnian sand from the orogen formed several small sand rich submarine fans lower head formation and correlative units on the lower reaches of the inner slope and basin plain the fans may have been fed by closely spaced rivers draining the orogen as presently occurs in western south america only proximal portions of these fans are now exposed the flysch basin was narrow constricted by the inner slope and the passive ma

reappraisal of the cambrian glauconite bearing anse maranda formation quebec appalachians from deep sea turbidites to clastic shelf deposits the cambrian anse maranda formation is a glauconite bearing clastic succession within the quebec reentrant it is part of the appalachians humber zone particularly of the shale feldspathic sandstone assemblage which represents the rift to drift deposits of the laurentian margin the massive sandstones of the anse maranda were originally interpreted as the proximal turbidites of a deep sea fan the occurrence of glauconite and the high degree of bioturbation which give the sandstones a massive aspect suggest a different depositional environment detailed ichnology and lithofacies descriptions indicate that the anse maranda predominantly represents shelf sediments deposited in storm influenced environment and that intense bioturbation destroyed most of the sedimentary structures the paleo geographic reconstruction suggests that the anse maranda was deposited seaward of a headland identified as the montmorency promontory along a narrow shelf with an irregular topography some coeval turbidites of sim

synthesis of palaeozoic deformational events and terrane accretion in the canadian appalachians plate tectonic theory predicts that most deformation is associated with subduction and terrane accretion with some deformation associated with transform transcurrent movements deformation associated with subduction varies between two end members 1 where the tectonic regime is dominated by subduction of oceanic lithosphere containing small terranes a narrow surface zone of accretionary deformation along the subduction zone starts diachronously on the subducting plate at the trench as material is transferred from the subducting plate to the over riding plate and 2 where continent continent collision is occurring a wide surface zone of accretionary deformation starts synchronously or with limited diachronism palaeozoic deformational events in the canadian appalachians correspond to narrow diachronous events in the ordovician and silurian whereas devonian carboniferous and permian deformational events are widespread and broadly synchronous along the western side of the canadian appalachians the taconian deformational event starts diachronously throughout the ordovician and corresponds to the north north west accretion of the notre dame ascot weedon st victor and various ophiolitic massifs volcanic arc and peri arc terranes over cratonic north america within the eastern half of the central mobile belt the late cambrian early ordovician penobscotian deformational event corresponds to the south easterly accretion of the exploits subzone various volcanic are and peri arc terranes over the gander zone continental rise in the centre of the orogen the late ordovician silurian beothukan deformational event corresponds to the south easterly accretion of the notre dame over the exploits gander subzones along the south eastern side of the central mobile belt the silurian ganderian deformational event corresponds to the north north east sinistral transcurrent accretion of the avalon composite terrane microcontinent over the gander exploits zones along the south eastern half of the orogen the late silurian middle devonian acadian deformation event corresponds to the westerly accretion of the meguma terrane intradeep or continental rise over the avalon composite terrane affecting the entire orogen the late devonian carboniferous and permian acadian alleghanian deformational events correspond to the east west convergence between laurentia and gondwana continent continent collision

the 1786 earthquake triggered landslide dam and subsequent dam break flood on the dadu river southwestern china abstract chinese historic documents recorded that on june 1 1786 a strong m 7 75 earthquake occurred in the kangding luding area sichuan southwestern china resulting in a large landslide that fell into the dadu river as a result a landslide dam blocked the river ten days later the sudden breaching of the dam resulted in catastrophic downstream flooding historic records document over 100 000 deaths by the flood this may be the most disastrous event ever caused by landslide dam failures in the world although a lot of work has been carried out to determine the location magnitude and intensity of the 1786 earthquake relatively little is known about the occurrence and nature of the landslide dam in this paper the dam was reconstructed using historic documents and geomorphic evidence it was found that the landslide dam was about 70 m high and it created a lake with a water volume of about 50 106 m3 and an area of about 1 7 km2 the landslide dam breached suddenly due to a major aftershock on june 10 1786 the peak discharge at the dam breach was estimated using regression equations and a physically based predictive equation the possibility of a future failure of the landslide seems high particularly due to inherent seismic risk and detailed geotechnical investigations are strongly recommended for evaluating the current stability of the landslide

evaluation of factors controlling earthquake induced landslides caused by chi chi earthquake and comparison with the northridge and loma prieta events over 10 000 landslides were triggered by the september 21 1999 chi chi earthquake a large number of these landslides have been mapped from spot images and a smaller number were described in a detailed field investigation geographic information systems gis was used to conduct a spatial characterization of the slope failures including distribution of type size slope angle bedrock geology ground motion and distance from earthquake source the most abundant landslides were shallow disaggregated rock and soil slides landslides occurred primarily in tertiary sedimentary rocks which are well known for their susceptibility to landsliding in many parts of the world landslide concentration values diminish beyond epicentral distances of 40 and 70 km from the epicenter and the surface projection of the fault plane respectively ground motion was found to be the most significant factor in triggering the shallow landslides in the chi chi earthquake overall 74 of all slope failures occurred in regions with vertical ground motions greater than 0 2g and 81 of all slope failures occurred in the region with mean horizontal peak ground accelerations pga greater than 0 15g these factors were used to compare landslides generated by the chi chi earthquake to the landslides triggered by the 1989 loma prieta earthquake and the 1994 northridge earthquake the major difference in distribution of landslides between the chi chi earthquake and the two california earthquakes was the distribution of slope angles in the chi chi earthquake 90 of the failures occurred on slopes steeper than 45 while more than 80 of failures occurred on slopes less than 50 in california apparently reflecting much steeper and tectonically more active geologic setting in taiwan

timing and seismic origin of nixu rock avalanche in southern tibet and its implications on nimu active fault abstract in tectonically active mountain areas the identification dating and determination of origin of large landslides are of special importance in recognizing the seismicity and earthquake magnitude of regional faults reconstructing the prehistoric landscape evolution and estimating the seismic hazards based on field survey high resolution satellite image interpretation and 14c dating of substrate this paper studied the large long runout nixu rock avalanche the nxra in the angang graben of the southern tibetan plateau the study revealed that 1 the deep seated nixu rock avalanche straddles the nimu active normal fault and spreads onto the angang basin with a deposit volume of 47 mm3 and a travelling distance of 4960 m 2 humus samples immediately under the deposit of rock avalanche along the natural river erosion section suggest a 14c age of 820 30 bp 1220 30 calad for the nxra event the age well matches the 1264 ce chubushi earthquake recorded in tibetan documents 3 23 adjacent landslides have been recognized with co seismic distribution features such as clustering and distance effect ridge end amplification effect and slope aspect effect sand liquefaction and peat deformation were discovered in the substrate beneath and at a distance of 300 m away from the avalanche deposit 4 this information indicate that the nxra was triggered most likely by the 1264 chubushi earthquake with a magnitude of mw 7 0 7 2 estimated by empirical equations of keefer 1994 and wells coppersmith 1994 it is suggested that the nimu fault of the yadong gulu rift may be more hazardous than the northern and southern part due to its high susceptibility of large co seismic landslides

upper middle ordovician submarine fans and associated facies northeast of quebec city autochthonous upper middle ordovician strata northwest of logan s line and northeast of quebec city have been subdivided into six facies types one or more facies type characterizes the revised formations of our previous report belt et al these facies were deposited in the following depositional environments moderately shallow carbonate bank deeper carbonate slope and foot of slope submarine fan and basin plain the submarine fan facies beaupre and saint irenee formations contain the only facies with appreciable sandstone the source region of the sandstones determined by petrography and paleocurrents lay to the southeast of logan s line this source was uplifted and eroded during the early phases of the taconic orogeny turbidity currents and debris flows brought sand into a foredeep trough that lay between the mobile taconic orogen and the more stable canadian shield during trenton time a carbonate bank developed on the margin of the shield northwest of the trough axis olistostromes pro

landslides earthquakes and erosion this paper relates landslide inventories to erosion rates and provides quantitative estimates of the landslide hazard associated with earthquakes we do this by utilizing a three parameter inverse gamma distribution which fits the frequency area statistics of three substantially dcompletet landslide event inventories a consequence of this general distribution is that a landslide event magnitude ml lognlt can be introduced where nlt is the total number of landslides associated with the landslide event using this general distribution landslide event magnitudes ml can be obtained from incomplete landslide inventories and the total area and volume of associated landslides as well as the area and volume of the maximum landslides can be directly related to the landslide event magnitude using estimated recurrence intervals for three landslide events and the time span for two historical inventories we estimate regional erosion rates associated with landslides as typically 0 1 2 5 mm year 1 we next give an empirical correlation between the earthquake magnitude associated landslideevent magnitude and the total volume of associated landslides using these correlations we estimate that the minimum earthquake magnitudes that will generate landslides is m 4 3f0 4 finally using gutenberg richter frequency magnitude statistics for regional seismicity we relate the intensity of seismicity in an area and the magnitude of the largest regional earthquakes to erosion rates we find that typical seismically induced erosion rates in active subduction zones are 0 2 7 mm year 1 and adjacent to plate boundary strike slip fault zones are 0 01 0 7 mm year 1

change in position and altitude of a small outlet glacier during the period 1943 92 leverett glacier west greenland fluctuations in the position and surface altitude of leverett glacier a small outlet glacier at the western margin of the greenland ice sheet are determined from a photogrammetric analysis

lower paleozoic configuration of the quebec reentrant based on improved along strike paleogeography an improved paleogeography of the quebec reentrant has been achieved by examining the nature and distribution of major sediment buildups within this reentrant the quebec reentrant has one side produced by rift faults and one side by a major transform fault the oak hill group was deposited near a triple rift zone clastic sediments of this group formed a large delta that was fed by a major river flowing in the rift valley of the ottawa graben the delta must have prograded on a gentle slope platform no other thick deltaic deposits are known towards the northeast instead facies analyses favor the existence of a promontory near quebec still farther to the northeast the saguenay graben was not the product of a triple rift junction however it served to funnel sediments to a deep sea fan and the adjacent platform was narrow with a steep slope the lateral distribution of sediments from the ordovician taconic orogeny can be explained by this improved paleogeographic reconstruction the configuration of

glacier advance ice marginal lakes and routing of meltwater and sediment russell glacier greenland the ice sheet margin at russell glacier west greenland advanced 7 m a 1 between 1968 and 1999 as the ice advanced over moraine ridges small changes in position caused major changes in the routing of proglacial water and sediment these included changes in the distribution of ice marginal lakes in the periodic drainage of ice dammed lakes in the routing and sediment content of meltwater draining into the proglacial zone and in the release of sediment from the moraines by erosion and mass movements proglacial hydrology and sediment flux appear to be controlled not simply by glacier mass balance but by evolving ice marginal geomorphology which must be accounted for in palaeoenvironmental interpretation of proglacial sediments

giant landslides topography and erosion abstract distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength it has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief limiting landsliding rather than gradual slope steepening here we test this concept by investigating the relationship between mean local relief h which we take to be a proxy of long term erosion rates e and the occurrence of over 300 of the largest v 10 8 m 3 terrestrial landslides on earth we find that nearly two thirds of these giant landslides have occurred in the steepest 5 of the earth s land surface where relief is close to its proposed upper strength limit they are primarily located in deeply incised valleys along fault bounded fringes of active mountain belts and in volcanic arcs this distribution coincides with areas of high long term erosion rates 4 mm yr 1 confirming that giant landslides contribute to rapid denudation of mountains most of the eroded volume is concentrated in the smallest but steepest parts of mountain belts and volcanic arcs first order estimates of minimum erosion rates accomplished by the largest landslides are 0 01 mm yr 1 these rates are between 1 and 10 of the late pleistocene to holocene mean erosion rates in a given area importantly the landslide erosion rates show a nonlinear increase with mean local relief suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates however giant landslides also occur in areas of lower than average relief h 300 700 m irrespective of whether threshold hillslopes have developed or not factors contributing to these failures include soft rocks extensive low angle discontinuities high rates of fluvial bedrock incision and tectonically driven deformation and slope loading

changes in morphology at the margin of the greenland ice sheet leverett glacier in the period 1943 1992 a quantitative analysis changes in ice marginal morphology near leverett glacier a small outlet glacier at the western margin of the greenland ice sheet are determined from a photogrammetrical analysis to be able to compare two datasets from subsequent years with measurements at different coordinates kriging was used for interpolation in this study the kriging standard error is used to evaluate the relative accuracy of the resulting maps aerial photographs of 1943 1968 and 1985 were compared in the period 1943 1968 an area of 0 2 106 m2 was deglaciated approximately 1 1 10 m3 of material is deposited in this area the southern part of the deglaciated area is characterized by ice cored moraines while moraines without ice core were formed in the north differences in depositional products reflect differences in meltwater activity and probably ice marginal thermal regime during deglaciation a small proglacial sandur decreased in altitude by 3 2 0 1 m from the early 1970s leverett glacier advanced over a previously deglaciated area during this advance small ice marginal accumulations were incorporated and eroded by the advancing glacier erosion products were for a substantial part stored in the proglacial sandur about 1 2 105 m2 of the northern part of an ice cored moraine complex decreased in altitude by 3 6 0 1 m from 1943 to 1968 and over 2 7 104 m2 by 2 7 0 1 m during 1968 1985 the spatial patterns of altitude change were analysed in relation to topomorphological parameters as exposition and slope angle and areas occupied by lakes the estimated energy used to melt the subsurface ice of the ice cored moraine is 1 4 2 2 w m2 1943 1968 and 1 0 1 6 w m2 1968 1985 these values are 30 50 times larger than the geothermal heat flux for the expected average debris concentration of the ice core 10 per cent by volume the deviation of the surface energy balance forced by climate change will be small and encompass an insignificant part of the total estimated energy used for melting

landslide mobility and hazards implications of the 2014 oso disaster abstract landslides reflect landscape instability that evolves over meteorological and geological timescales and they also pose threats to people property and the environment the severity of these threats depends largely on landslide speed and travel distance which are collectively described as landslide mobility to investigate causes and effects of mobility we focus on a disastrous landslide that occurred on 22 march 2014 near oso washington usa following a long period of abnormally wet weather the landslide s impacts were severe because its mobility exceeded that of prior historical landslides at the site and also exceeded that of comparable landslides elsewhere the 8 10 6 m 3 landslide originated on a gently sloping

nature and timing of large landslides within an active orogen eastern pamir china abstract large scale landsliding involving 106 m3 in volume is important in landscape development in high mountains to assess the importance of large landslides in high mountains four large landslides bulunkou muztagh taheman and yimake were mapped in the ne chinese pamir at the westernmost end of the himalayan tibetan orogen and dated using 10be terrestrial cosmogenic nuclides the bulunkou landslide at the southernmost end of muji valley is composed of 1 7 107 m3 of landslide debris and has an age of 2 0 0 1 ka the muztagh landslide located on the sw side of the massif muztagh ata is composed of 4 7 108 m3 of debris and has an age of 14 3 0 8 ka the taheman landslide located south of muztagh ata is composed of 2 6 108 m3 of landslide debris and has an age of 6 8 0 2 ka the yimake landslide on the northern frontal range of the pamir at the southwestern end of the tarim basin is composed of 1 4 109 m3 of landslide debris and has an age of 7 1 0 6 ka two other large landslides are present in the region the aerpa aigezi on a tributary of the gez river and the bile jiyi on the yarkand river landslides and are composed of 1 6 107 m3 and 5 2 106 m3 of landslide debris respectively however the aerpa aigezi and bile jiyi landslides were not studied in as much detail or dated because of their inaccessibility given the tectonically active nature of this region with numerous active faults and the morphology of the landslides these landslides were likely triggered by earthquakes however other causes including long term increased precipitation and geologic bedrock structure could be important contributing factors in their formation