why permafrost rocks become unstable a rock ice mechanical model in time and space in this paper we develop a mechanical model that relates the destabilisation of thawing permafrost rock slopes to temperature related effects on both rock and ice mechanics and laboratory testing of key assumptions is performed degrading permafrost is considered to be an important factor for rock slope failures in alpine and arctic environments but the mechanics are poorly understood the destabilisation is commonly attributed to changes in ice mechanical properties while bedrock friction and fracture propagation have not been considered yet however fracture toughness compressive and tensile strength decrease by up to 50 and more when intact water saturated rock thaws based on literature and experiments we develop a modified mohr coulomb failure criterion for ice filled rock fractures thatincorporates fracturing of rock bridges friction of rough fracture surfaces ductile creep of ice and detachment mechanisms along rock ice interfaces novel laboratory setups were developed to assess the temperature dependency of the friction of ice free rock rock interfaces and the shear detachment of rock ice interfaces indegrading permafrost rock mechanical properties may control early stages of destabilisation and become more important for higher normal stress i e higher magnitudes of rock slope failure ice mechanical properties outbalance the importance of rock mechanical components after the deformation accelerates and are more relevant for smaller magnitudes the model explains why all magnitudes of rock slope failures can be prepared and triggered by permafrost degradation and is capable of conditioning long paraglacial response times here we present a synoptic rock and ice mechanical model that explains the mechanical destabilisation processes operating in warming permafrost rocks

spatial and temporal variations in rockfall determined from tls measurements in a deglaciated valley switzerland steep u shaped valleys produced by glaciation are commonly eroded by rockfall in this study we investigate modern and long term power law predicted rates of rock wall retreat in a deglaciated valley our emphasis is on the 5 2 km2 calcareous cliffs covering in the lauterbrunnen valley switzerland terrestrial laser scans were collected during nine field campaigns over 18 months to provide a continuous coverage of most of the valley walls results indicate a total of 122 rockfalls with volumes ranging between 0 06 0 01 and 119 34 1 07 m3 different size groups of rockfall events were correlated with environmental factors e g freeze thaw cycles temperature precipitation and seismicity using a linear regression with variable lag times of 0 6 months the highest correlation factor r 0 6 p 0 08 90 significance level is observed for freeze thaw cycles and rockfall events smaller than 1 m3 with a 2 month delay between temperature extremes and rockfall frequency magnitude relationships for rockfall events were calculated to predict less frequent larger rockfall events that did not occur during the observation period a monte carlo analysis was applied to the frequency magnitude relationship to evaluate the sensitivity of results to their stochastic nature an average power law exponent of 1 71 0 09 was calculated using linear regression the calculated exponents are similar to other studies in calcareous rock settings conducted over different observation durations finally we determine an average total eroded volume of 2 0 0 01 0 6 103 m3 yr and a corresponding long term power law predicted cliff retreat rate of 0 39 0 02 0 12mm yr

terrestrial laser scanning of rock slope instabilities this manuscript presents a review on the application of a remote sensing technique terrestrial laser scanning tls to a well known topic rock slope characterization and monitoring although the number of publications on the use of tls in rock slope studies has rapidly increased in the last 5 10 years little effort has been made to review the key developments establish a code of best practice and unify future research approaches the acquisition of dense 3d terrain information with high accuracy high data acquisition speed and increasingly efficient post processing workflows is helping to better quantify key parameters of rock slope instabilities across spatial and temporal scales ranging from cubic decimetres to millions of cubic metres and from hours to years respectively key insights into the use of tls in rock slope investigations include a the capability of remotely obtaining the orientation of slope discontinuities which constitutes a great step forward in rock mechanics b the possibility to monitor rock slopes which allows not only the accurate quantification of rockfall rates across wide areas but also the spatio temporal modelling of rock slope deformation with an unprecedented level of detail studying rock slopes using tls presents a series of key challenges from accounting for the fractal character of rock surface to detecting the precursory deformation that may help in the future prediction of rock failures further investigation on the development of new algorithms for point cloud filtering segmentation feature extraction deformation tracking and change detection will significantly improve our understanding on how rock slopes behave and evolve perspectives include the use of new 3d sensing devices and the adaptation of techniques and methods recently developed in other disciplines as robotics and 3d computer vision to rock slope instabilities research

structural and thermal controls of rockfall frequency and magnitude within rockwall talus systems swiss alps both from a systemic and natural hazard perspective it is essential to understand the causes and frequency of rockfalls in mountain terrain and to predict the block sizes deposited at specific locations commonly rockfalls are studied either retrospectively using talus slopes or directly by rockwall surveys nevertheless our understanding of rockfall activity particularly at the lower magnitude spectrum is still incomplete moreover the explanatory framework is rarely addressed explicitly in this study we investigate two rockwall talus systems in the swiss alps to estimate the rockfall frequency magnitude pattern and their key controls we present a holistic approach that integrates deductive geotechnical and thermal investigations of the source rockwalls with abductive talus based explanations of rockfall volume and frequency the rockwalls three dimensional 3d joint pattern indicates that 75 of the blocks may be released as debris fall 14 m3 and boulder falls 14 61 m3 which is mirrored in the corresponding talus material using two year records of near surface rockwall temperatures as input for a 1d heat conduction model underlines the destabilizing role of seasonal ice segregation deepest frost cracking of 300 cm may occur on the north northeast nne exposed snow rich rockwall with peaks at the outermost surface the synthesis of all data suggests that infrequent large planar slides approximately every 250 years overlain by smaller more frequent wedge and toppling failures approximately every 17 50 years as well as high frequency flake like clasts 3 6 events year characterize the rockfall frequency magnitude pattern at hungerli peak here we argue that small size rockfalls need more scientific attention particularly in discontinuous permafrost zones our study emphasizes that future frequency magnitude research should ideally incorporate site specific structural and thermal properties rather than just focusing on climatic or meteorological triggers we discuss how holistic rockwall talus approaches as proposed here could help to increase our process understanding of rockfalls in mountain environments copyright 2017 john wiley sons ltd

influence of typhoons and earthquakes on rainfall induced landslides and suspended sediments discharge abstract the aim of this paper is to present data on the occurrence of landslides triggered by typhoon and earthquake events and to discuss the basic earthquake triggering mechanisms involved four events of typhoon and earthquake triggered landslides in the chenyoulan river catchment of central taiwan during 1996 to 2004 were studied in order to identify their controlling factors the landslides areas were measured by comparing aerial photos taken over the past 18 years and sediment discharge was counted at hydrometric stations investigation results demonstrate that hillslope geomaterials that had been disturbed by strong seismic shaking induced expansion of landslide areas during subsequent events analysis of normalized difference vegetation index ndvi also registered the changes of uncovered conditions on the hillslope caused by landsliding when flow discharge is lower than 100 m 3 s 1 post seismic sediment concentration is roughly four times higher than pre seismic concentration with the same flow discharge this fate indicates that the amount of sediment discharge at normal flow discharge is affected by supplied sediment volume which tends to increase with seismic activity

n alkane evidence for the onset of wetter conditions in the sierra nevada california usa at the mid late holocene transition 3 0 ka abstract n alkane biomarker distributions in sediments from swamp lake sl in the central sierra nevada of california usa provide evidence for an increase in mean lake level 3000 yr ago in conjunction with widespread climatic change inferred from marine and continental records in the eastern north pacific region length distributions of n alkane chains in modern plants growing at sl were determined and compared to sedimentary distributions in a core spanning the last 13 ka as a group submerged and floating aquatic plants contained high proportions of short chain lengths nc27 were dominant changes in the sedimentary n alkane distribution over time were driven by variable inputs from plant sources in response to changing lake level sedimentation and plant community composition a shift toward shorter chain lengths nc21 nc23 occurred between 3 1 and 2 9 ka and is best explained by an increase in the abundance of aquatic plants and the availability of shallow water habitat in response to rising lake level the late holocene expansion of sl following a dry mid holocene is consistent with previous evidence for increased effective moisture and the onset of wetter conditions in the sierra nevada between 4 0 and 3 0 ka

distributions of landslides vegetation and related sediment yields during typhoon events in northwestern taiwan abstract this study examined landslides caused by typhoon events in the upstream area of the tao cheng river in northwestern taiwan during a 13 year period 1996 to 2008 data from six typhoon events were compiled to analyze the relevant characteristics of landslides vegetation and changes in sediment discharge with particulate carbon in rivers in this area the landslide ratio the ratio of the landslide area to the total study area was determined to be between 0 60 and 1 29 and a high new generation ratio and low reactivated ratio of landslides were noted analysis of different bands of satellite images taken over a 10 year period disclosed that the normalized difference vegetation index ndvi in the upstream area of the tao cheng river ranged from 0 47 to 0 63 before typhoon events and from 0 38 to 0 46 after typhoon events the low landslide ratio and high new generation ratio in this area indicated that sporadic landslides tend to occur in new areas and do not have a great impact on vegetation conditions thus the decrease in ndvi after typhoon events was caused by the seasonal effect with withering of vegetation on the other hand landslides in this area tend to occur on nonforest land because of the interventions of external forces such as human developments and reclamation geological materials produced by landslides and vegetation flushed by heavy rainfall during typhoon periods have a great effect on the amount of sediment discharge and particulate carbon discharge in the rivers furthermore during typhoon periods the amount of accumulated rainfall has a greater impact than the peak rainfall intensity on the increase of sediment and particulate carbon in rivers and on the decrease in the ndvi analysis of the particulate carbon from the rivers in this area revealed that in the rainy season high strength and accumulated rainfall will lead to more sediment discharge and particulate carbon discharge in rivers however the particulate carbon is limited with further increases in rainfall because of the limited supply of particulate carbon in the upstream of the tao cheng river

an organic geochemical record of sierra nevada climate since the lgm from swamp lake yosemite abstract sediment records from swamp lake sl in the central sierra nevada california provide evidence of climatic change on millennial and centennial timescales over the last 20 000 years total organic carbon toc abundance varied in concert with elemental and isotopic tracers of organic matter c n 13 c org 15 n biogenic silica content total magnetic susceptibility and sediment lithology we interpret the down core proxy records as representing the response of the lake environment in terms of temperature seasonal ice cover mixing regimes runoff and in situ om and nutrient cycling to shifting climate states these environmental factors in turn drove changes in algal productivity om sources microbial om regeneration and secondary production and detrital input the late pleistocene 19 7 10 8 cal kyr bp was dominated by fluctuations between relatively warm dry intervals with high toc 17 4 16 5 15 8 15 0 13 9 13 2 11 4 11 0 cal kyr bp and cold wet intervals 16 5 15 8 14 8 13 9 13 1 11 6 11 0 10 7 cal kyr bp characterized by low toc and high detrital input the holocene 10 7 cal kyr bp present was characterized by three abrupt increases in toc after 10 8 8 0 and 3 0 cal kyr bp and numerous century scale fluctuations toc increases reflected enhanced lake productivity and om recycling and reduced detrital input in response to changing winter temperature and hydrologic regimes inferred environmental changes at sl correlate with other sierra nevada paleorecords and with reconstructed sea surface temperatures along the california margin parallel changes in the sl and sst records over the past 20 000 years provide new evidence that continental climate in the sierra nevada and the california current system have responded on multiple timescales to common drivers in north pacific ocean atmospheric circulation

landslide hazard evaluation a review of current techniques and their application in a multi scale study central italy in recent years growing population and expansion of settlements and life lines over hazardous areas have largely increased the impact of natural disasters both in industrialized and developing countries third world countries have difficulty meeting the high costs of controlling natural hazards through major engineering works and rational land use planning industrialized societies are increasingly reluctant to invest money in structural measures that can reduce natural risks hence the new issue is to implement warning systems and land utilization regulations aimed at minimizing the loss of lives and property without investing in long term costly projects of ground stabilization government and research institutions worldwide have long attempted to assess landslide hazard and risks and to portray its spatial distribution in maps several different methods for assessing landslide hazard were proposed or implemented the reliability of these maps and the criteria behind these hazard evaluations are ill formalized or poorly documented geomorphological information remains largely descriptive and subjective it is hence somewhat unsuitable to engineers policy makers or developers when planning land resources and mitigating the effects of geological hazards in the umbria and marche regions of central italy attempts at testing the proficiency and limitations of multivariate statistical techniques and of different methodologies for dividing the territory into suitable areas for landslide hazard assessment have been completed or are in progress at various scales these experiments showed that despite the operational and conceptual limitations landslide hazard assessment may indeed constitute a suitable cost effective aid to land use planning within this framework engineering geomorphology may play a renewed role in assessing areas at high landslide hazard and helping mitigate the associated risk

late holocene upper timberline variation in the southern sierra nevada alpine timberline has been shown to be a definite tension zone between trees and climate where trees invade higher ground during favourable climatic periods and retreat during periods of deteriorating conditions1 these movements are indicative of an upper forest limit sensitively adjusted to climatic variation here i present absolutely dated dendrochronological records from living trees and standing snags and radiometric dates from relict logs of foxtail pine at cirque peak southern sierra nevada california providing the first detailed record of temperature induced mid to late holocene fluctuations in sierran timberline marked declines in timberline correspond to lichen dated cold periods and or glacial advance

assessing ams 14c ages of detrital organics from holocene and late pleistocene moraines east central sierra nevada california usa obtaining age estimates of moraines which have insufficient carbon for conventional 14 c dating may be possible by ams 14 c dating of detrital organic material in the till matrix sufficient detrital carbon was available in the till matrix of holocene and late pleistocene moraines of upper laurel creek canyon east central sierra nevada california for ams 14 c measurements radiocarbon analysis of till matrix organics from the moraine closest to the headwall ml reveals an age of 2875 60 bp eth 13550 the next oldest moraine m2 yields 4450 60 bp eth 12810 m3 the oldest moraine in the bloody mountain cirque yielded organics with a radiocarbon age of 13 600 120 bp eth 12812 while results are preliminary these ages are among the first on till matrix in the sierra nevada and are consistent with geomorphic context other palaeoecologic records in the sierra nevada and palaeolake records in the western united states

tree ring evidence for climatically effective volcanic eruptions abstract ringwidth variations from temperature sensitive upper timberline sites in the sierra nevada show a marked correspondence to the decadal pattern of volcanic sulfate aerosols recorded in a greenland ice core acidity profile and a significant negative growth response to individual explosive volcanic events the appearance of single events in the mid latitude tree ring record in connection with ice core evidence from the arctic and historical records from the mediterranean indicates that the majority of these events represent climatically effective volcanic eruptions producing temperature decreases on the order of 1 c for up to 2 yr after the initial eruption clusters of climatically effective volcanic events may serve as a trigger to glaciation and are consistently associated with lowered ringwidths and late holocene glacier advance in the sierra nevada the tree ring record strongly suggests forcing of solar radiation receipt and temperatures by increased volcanic aerosols especially during the recess peak advances and matthes little ice age advances from 1400 to 1850 a d intervals with an absence of significant volcanic aerosol production or historically documented eruptive activity correspond to intervals of significantly increased indexed ringwidth values minimal numbers of severe annual negative ringwidth anomalies and an absence of glacial deposits in the southern sierra nevada

monitoring playa lake inundation in the western united states modern analogues to late holocene lake level change abstract closed basin playas are among the most sensitive hydrologic systems globally and are excellent indicators of current and past climatic variability this variability can significantly impact hydrologic regimes and biotic communities and is often expressed in lake bed deposits and shoreline features we analyzed two playa basins in western north america that lie to either side of the current divide between monsoon and westerly precipitation regimes using a 23 year sequence of landsat images at a 16 day time step we determined the playa inundation response to varying precipitation inputs our results show that a strongly contrasting lake inundation response occurs in lake basins separated by only 200 km the animas lordsburg basin shows a marked lake area increase in response to winter precipitation events while the more southerly palomas basin shows a stronger response to monsoonal and el nino type events this sensitivity to different input sources over short distances may explain some of the apparent asynchronous behavior of playa response found in lake records comprehensive regional scale inundation records could be used to understand the dynamics of playa inundation events and how these events are linked to atmospheric circulation and possibly to understand the observed asynchronous behavior of lake basins during the late pleistocene and holocene

glacier variations in the sierra nevada california as related to a 1200 year tree ring chronology abstract a time series of tree ringwidth indices for alpine timberline foxtail pine pinus balfouriana from the sierra nevada of california shows a growth response to summer late fall and early winter temperatures that is the inverse of that resulting in the expansion of alpine glaciers these are correlated with lichen dated moraines and avalanche deposits that accumulated during subsequent decades minima in the ringwidth record reflecting marked temperature declines occurred at 810 1470 1610 1700 and 1810 cold periods of lesser extent are also indicated between 1190 to 1400 and suggest that the initial pulses of the sierran matthes advances may have begun as early as 1190 or 150 yr earlier than previously dated the matthes advances were preceded by a period of pronounced warmth from 900 to 1190 during which timberline rose 10 m to its present elevation a warm period is also indicated between 1500 and 1580 recent work extending the tree ring chronology to 3031 yr b p and radiocarbon dating of weathered samples to 6300 yr b p suggests that the chronology may ultimately be applicable to the dating of earlier sierran glacier advances

sediment yield during typhoon events in relation to landslides rainfall and catchment areas in taiwan abstract debris sourced from landslides will result in environmental problems such as increased sediment discharge in rivers this study analyzed the sediment discharge of 17 main rivers in taiwan during 14 typhoon events selected from the catchment area and river length that caused landslides according to government reports the measured suspended sediment and water discharge collected from hydrometric stations of the water resources agency of taiwan were used to establish rating curve relationships a power law relation between them then sediment discharge during typhoon events was estimated using the rating curve method and the measured data of daily water discharge positive correlations between sediment discharge and rainfall conditions for each river indicate that sediment discharge increases when a greater amount of rainfall or a higher intensity of rainfall falls during a typhoon event in addition the amount of sediment discharge during a typhoon event is mainly controlled by the total amount of rainfall not by peak rainfall differences in correlation equations among the rivers suggest that catchments with larger areas produce more sediment catchments with relatively low sediment discharge show more distinct increases in sediment discharge in response to increases in rainfall owing to the little opportunity for deposition in small catchments with high connectivity to rivers and the transportation of the majority of landslide debris to rivers during typhoon events also differences in geomorphic and geologic conditions among catchments around taiwan lead to a variety of suspended sediment dynamics and the sediment budget positive correlation between average sediment discharge and average area of landslides during typhoon events indicates that when larger landslides are caused by heavier rainfall during a typhoon event more loose materials from the most recent landslide debris are flushed into rivers resulting in higher sediment discharge the high proportion of large landslides in taiwan contributes significantly to the high annual sediment yield which is among the world s highest despite the small area of taiwan

a 2000 year tree ring record of annual temperatures in the sierra nevada mountains tree ring data have been used to reconstruct the mean late season june through january temperature at a timberline site in the sierra nevada california for each of the past 2000 years long term trends in the temperature reconstruction are indicative of a 125 year periodicity that may be linked to solar activity as reflected in radiocarbon and auroral records the results indicate that both the warm intervals during the medieval warm epoch a d 800 to 1200 and the cold intervals during the little ice age a d 1200 to 1900 are closely associated with the 125 year period significant changes in the phase of the 125 year temperature variation occur at the onset and termination of the most recent radiocarbon triplet and may indicate chaotic solar behavior

evidence of a higher late holocene treeline along the continental divide in central colorado using a combination of 23 radiocarbon ages and annual ring counts from 18 rocky mountain bristlecone pine pinus aristata remnants above the local present day limits a period of higher treeline has been determined for two sites near the continental divide in central colorado the highest remnants were found about 30 m above live bristlecone pines of similar size the majority of the remnants consisting of standing snags large logs and smaller remains are highly eroded such that the innermost annual rings of all but one are missing the radiocarbon ages obtained from the oldest wood recovered from each remnant indicate that the majority were established above the present day limit of bristlecone pine from prior to 2700 cal yr bp to no later than about 1200 cal yr bp these radiocarbon ages combined with the annual ring count from the corresponding remnant indicate that the majority of the sampled remnants grew above the present day limit of bristlecone pine from sometime before 2700 cal yr bp to

riverine particulate organic carbon from an active mountain belt importance of landslides 1 we investigate the routing and transfer of particulate organic carbon poc from the western southern alps new zealand using organic carbon corg and nitrogen norg concentrations and stable carbon isotopes 13corg in this active mountain belt sediment discharge is dominated by landslide derived material landsliding acts to homogenize the geochemically diverse hillslope poc mixing poc from the standing biomass and soil with the fossil poc from bedrock as a result the poc in river sediment at the mountain front is a binary mixture of fossil and nonfossil carbon sourced from many landslide deposits we calculate that nonfossil biogenic poc makes up 63 7 of the total poc in the suspended load of rivers draining the western southern alps the erosional flux of biogenic poc from these catchments represents a transfer of 39 tc km 2 a 1 of atmospheric co2 averaged over the west flank of the mountain belt if more than 10 of this poc is preserved in sediments on geological timescales then this process is the most significant way in which the southern alps and similar tectonically active mountain belts with restricted alluvial aprons consume atmospheric co2

solifluction steps and risers lee ridge glacier national park montana usa a scale and pattern analysis solifluction patterns on lee ridge glacier national park montana usa were characterized through a combination of field transects enhanced digital aircraft data and geostatistics the objectives were to i assess the role of high spatial resolution digital imagery for mapping the areal extent and spatial pattern of solifluction steps and risers through digital enhancements i e principal components analysis pca and wavelet transforms wtfs of adar 5500 aircraft imagery ii describe the pattern of solifluction steps and risers through the placement of twelve 50 m field transects oriented normal to the steps and risers and organized along an elevational gradient extending from highest to lowest positions along the ridge iii define scale dependent relationships of the solifluction steps and risers mapped along one dimensional field transects and two dimensional remote sensing images using indicator semivariograms to define the structure of the spatial data across a range of sampled scales and iv relate the solifluction patterns observed through the transects and the remote sensing interpretations to topographic trends associated with distance from the dominant peak a proxy for elevation change along lee ridge findings suggest that the semivariance pattern of the transects changes with elevation that is the semivariograms of the lower transects show smaller amplitudes and shorter wavelengths than those at higher elevations and the pattern of steps and risers from the enhanced adar 5500 images indicate less variation in the semivariance with elevation than represented in the field transects

the late holocene dry period multiproxy evidence for an extended drought between 2800 and 1850 cal yr bp across the central great basin usa abstract evidence of a multi centennial scale dry period between 2800 and 1850 cal yr bp is documented by pollen mollusks diatoms and sediment in spring sediments from stonehouse meadow in spring valley eastern central nevada u s we refer to this period as the late holocene dry period based on sediment recovered stonehouse meadow was either absent or severely restricted in size at 8000 cal yr bp beginning 7500 cal yr bp the meadow became established and persisted to 3000 cal yr bp when it began to dry comparison of the timing of this late holocene drought record to multiple records extending from the eastern sierra nevada across the central great basin to the great salt lake support the interpretation that this dry period was regional the beginning and ending dates vary among sites but all sites record multiple centuries of dry climate between 2500 and 1900 cal yr bp this duration makes it the longest persistent dry period within the late holocene in contrast sites in the northern great basin record either no clear evidence of drought or have wetter than average climate during this period suggesting that the northern boundary between wet and dry climates may have been between about 40 and 42 n latitude this dry in the southwest and wet in the northwest precipitation pattern across the great basin is supported by large scale spatial climate pattern hypotheses involving enso pdo amo and the position of the aleutian low and north pacific high particularly during winter

quantification of long term erosion rates from root exposure tree age relationships in an alpine meadow catchment abstract erosion rates derived using dendrogeomorphology have been used to quantify slope degradation in many localities globally however with the exception of the western united states most of these estimates are derived from short lived trees whose lifetimes may not adequately reflect the complete range of slope processes which can include erosion deposition impacts of extreme events and even long term hiatuses erosion rate estimates at a given site using standard techniques therefore reflect censored local point erosion estimates rather than long term rates we applied a modified dendrogeomorphic approach to rapidly estimate erosion rates from dbh age relationships to assess the difference between short and long term rates and found that the mean short term rate was 0 13 cm yr with high variability while the uncensored long term rate was 0 06 cm yr the results indicate that rates calculated from short lived trees while possibly appropriate for local short term point estimates of erosion are highly variable and may overestimate regional long term rates by 50 while these findings do not invalidate the use of dendrogeomorphology to estimate erosion rates they do suggest that care must be taken to select older trees that incorporate a range of slope histories in order to best approximate regional long term rates

late quaternary snowline reconstructions for the southern and central sierra nevada california and a reassessment of the recess peak glaciation abstract in the sierra nevada the recess peak glaciation has been previously defined on the basis of deposits exhibiting relative age characteristics intermediate between those of the little ice age deposits and those of early holocene or older moraines in the absence of reliable chronological control the recess peak deposits were assigned an early neoglacial age although numerous moraines in the central and southern sierra have been attributed to this interval regional snowline gradients reconstructed from these deposits lack internal consistency and appear to represent several distinctly different episodes of glacier advance as a basis for comparison with the recess peak data modern and late pleistocene regional snowlines were reconstructed using accumulation area ratios and cirque floor altitudes these reconstructions display regionally consistent gradients rising gradually southward and more steeply eastward based on these data the full glacial late pleistocene snowline depression is estimated to have been 800 m estimates of recess peak snowline depression vary widely ranging from 140 to 500 m and a reconstructed regional gradient rises northward in opposition to the late pleistocene and modern snowlines limited radiocarbon dating and the irregular pattern derived from the recess peak snowline data suggest that even in the type area these deposits resulted from both pre and post hypsithermal glacier advances

terrestrial sedimentation and the carbon cycle coupling weathering and erosion to carbon burial this paper examines the linkages between the carbon cycle and sedimentary processes on land available data suggest that sedimentation on land can bury vast quantities of organic carbon roughly 1015 g c yr 1 to evaluate the relative roles of various classes of processes in the burial of carbon on land terrestrial sedimentation was modeled as a series of 864 scenarios each scenario represents a unique choice of intensities for seven classes of processes and two different global wetland distributions comparison was made with presumed preagricultural conditions the classes of processes were divided into two major component parts clastic sedimentation of soil derived carbon and organic sedimentation of autochthonous carbon for clastic sedimentation masses of sediment were considered for burial as reservoir sediment lake sediment and combined colluvium alluvium and aeolian deposits when the ensemble of models is examined the human induced burial of 0 6 1 5 1015 g yr 1 of carbon on land is entirely plausible this sink reaches its maximum strength between 30 and 50 n paddy lands stand out as a type of land use that warrants future study but the many faces of rice agriculture limit generalization in an extreme scenario paddy lands alone could be made to bury about 1 1015 g c yr 1 arguing that terrestrial sedimentation processes could be much of the sink for the so called missing carbon is reasonable such a hypothesis however requires major redesign of how the carbon cycle is modeled unlike ecosystem processes that are amenable to satellite monitoring and parallel modeling many aspects of terrestrial sedimentation are hidden from space

deglaciation and postglacial timberline in the san juan mountains colorado abstract lake emma which no longer exists because of a mining accident was a tarn in a south facing cirque near the headwaters of the animas river in the san juan mountains of southwestern colorado during the pinedale glaciation this area was covered by a large transection glacier centered over the lake emma region three radiocarbon dates on basal organic sediment from lake emma indicate that by ca 15 000 yr b p this glacier one of the largest in the southern rocky mountains no longer existed twenty two radiocarbon dates on picea and abies krummholz fragments in the lake emma deposits indicate that from ca 9600 to 7800 yr b p from 6700 to 5600 yr b p and at 3100 yr b p the krummholz limit was at least 70 m higher than present these data in conjunction with picea pinus pollen ratios from both the lake emma site and the hurricane basin site of j t andrews p e carrara f b king and r struckenrath 1975 quaternary research 5 173 197 suggest than from ca 9600 to 3000 yr b p timberline in the san juan mountains was higher than present cooling apparently began ca 3000 yr b p as indicated by decreases in both the percentage of picea pollen and picea pinus pollen ratios at the hurricane basin site andrews et al 1975 cooling is also suggested by the lack of picea or abies fragments younger than 3000 yr b p at either the lake emma or the hurricane basin site

holocene environmental change resets lichen surface dates on recess peak glacial deposits in the sierra nevada california abstract development of an accurate chronology for glacial deposits in the sierra nevada has long been problematic given the lack of suitable organic material for radiocarbon dating lichenometry initially appeared promising as ages showed an increase from cirque headwalls to down canyon moraines however while recess peak lichen age estimates range from 2 to 3 ka recent work shows these deposits to be at least 10 ka older here we present evidence for a late holocene reset of recess peak lichen ages by significant post depositional climate change following late pleistocene deposition of recess peak moraines warming through the mid holocene allowed forests to advance into shallow basins eliminating local inverted tree lines this produced a partial canopy where shading killed the original post pleistocene crustose lichen colonies late holocene cooling resulted in forest retreat from these basins as alpine tree line fell lichens then recolonized the re exposed recess peak deposits we conclude that while recess peak lichen ages are accurate to within the dating uncertainty of the technique existing lichen ages actually date the timing of post mid holocene cooling and recolonization and not the original emplacement of these deposits thus applications of lichenometry should consider post depositional environmental change when interpreting the meaning of these dates

landslides triggered by the 23 november 2000 rainfall event in the imperia province western liguria italy from mid october to 22 november 2000 the western liguria region of italy experienced prolonged and intense rainfall with cumulative values exceeding 1000 mm in 45 days the severe rainfall sequence ended on november 23 with a high intensity storm that dumped more than 180 mm of rain in 24 h the high intensity event caused flooding and triggered more than 1000 soils slips and debris flows and a few large complex landslides slope failures caused three fatalities and severe damage to roads private homes and agriculture large 1 13 000 and very large 1 5000 scale colour aerial photographs were taken 45 days after the event over the areas most affected by the landslides through the interpretation of the 334 photographs covering an area of 500 km2 we prepared a landslide inventory map that shows 1204 landslides for a total landslide area of 1 6 km2 we identified the rainfall conditions that triggered landslides in the armea valley using cumulative and continuous rainfall data combined with detailed information on the time of landslide occurrence landslide activity initiated 8 to 10 h after the beginning of the storm and the most abundant activity occurred in response to rainfall intensities of 8 to 10 mm per hour for the ceriana municipality an area where the landslides were numerous in november 2000 we also collected information about a historical event that occurred on 8 11 december 1910 and triggered abundant landslides resulting in severe economic damage a comparison of the damage caused by the historical and the recent landslide events indicated that damage caused by the 1910 historical event was more diffused but less costly than the damage caused by the 2000 event

distribution of landslides caused by heavy rainfall events and an earthquake in northern aso volcano japan from 1955 to 2016 abstract a new landslide cannot form until the soil has recovered to the critical depth for the recurrence of a landslide through the weathering of bedrock and soil transportation from adjacent areas in volcanic areas with tephra deposits landslides expose tephra and not bedrock therefore the immunity of landslides in volcanic areas may be different from that of landslides in non volcanic areas herein we developed landslide inventory maps lims for 6 periods during 1955 2016 using aerial photographs and digital elevation models in northern aso volcano in this area landslides were found to continuously occur due to rainfall events and a large earthquake using the 6 lims we examined the terrain attributes i e slope angle slope aspect and normalized distance to ridge and the overlap of landslides among the terrain attributes slope angle was a dominant factor affecting the occurrence of landslides caused by both rainfall events and an earthquake the total landslide areal density in 2016 was 50 for a slope angle of 35 45 2 atypical events a rainfall in july 2012 and an earthquake in april 2016 caused landslides to occur on slopes that were relatively resistant to landslides by typical amounts of rainfall resulting in high landslide density in 2016 the intensity of rainfall for an event in july 2012 was considerably higher than that for other rainfall events the type of landslides caused by an earthquake in april 2016 was different from that of landslides caused by rainfall the depths of some landslides caused by this earthquake were deeper than those of landslides caused by the rainfall in july 2012 the overlap ratio was

statistical analysis of an earthquake induced landslide distribution the 1989 loma prieta california event the 1989 loma prieta california earthquake moment magnitude m 6 9 generated landslides throughout an area of about 15 000 km2 in central california most of these landslides occurred in an area of about 2000 km2 in the mountainous terrain around the epicenter where they were mapped during field investigations immediately following the earthquake the distribution of these landslides is investigated statistically using regression and one way analysis of variance anova techniques to determine how the occurrence of landslides correlates with distance from the earthquake source slope steepness and rock type the landslide concentration defined as the number of landslide sources per unit area has a strong inverse correlation with distance from the earthquake source and a strong positive correlation with slope steepness the landslide concentration differs substantially among the various geologic units in the area the differences correlate to some degree with differences in lithology and degree of induration but this correlation is less clear suggesting a more complex relationship between landslide occurrence and rock properties

earthquake triggered increase in sediment delivery from an active mountain belt in tectonically active mountain belts earthquake triggered landslides deliver large amounts of sediment to rivers we quantify the geomorphic impact of the 1999 mw 7 6 chi chi earthquake in taiwan which triggered 20 000 landslides coseismic weakening of substrate material caused increased landsliding during subsequent typhoons most coseismic landslides remained confined to hillslopes downslope transport of sediment into the channel network occurred during later storms the sequential processes have led to a factor of four increase in unit sediment concentration in rivers draining the epicentral area and increased the magnitude and frequency of hyperpycnal sediment delivery to the ocean four years after the earthquake rates of hillslope mass wasting remain elevated in the epicentral area

late holocene paleoclimate and treeline fluctuation in wyoming s wind river range usa this study presents evidence for treeline advance in the central rocky mountains united states between 1800 and 800 cal yr bp this evidence was generated by systematic survey sampling and acc

a warning system for rainfall induced shallow failures abstract it is widely recognised that soil slips and debris flows are triggered by short intense storms owing its geologic geomorphologic and climatic settings the piedmont region nw italy is highly prone to the occurrence of this kind of landslides in the last two centuries in fact a total of 105 severe meteoric events which triggered shallow failures occurred and of these 18 events took place from 1990 to 2002 a fair number of rainfall thresholds have been proposed in the literature defined both on empirical or on physical bases empirical thresholds are defined collecting rainfall data for landslide meteoric events and for events without landslides while physical thresholds are based on numerical models that consider the relation between rainfall pore pressure and slope stability the main objective of this paper is the identification of the empirical triggering thresholds for the piedmont region four meteoric events were selected and analysed november 4 5 1994 july 7 8 1996 april 27 30 2000 october 13 16 2000 because they supply a wide range of variation for both rainfall parameters duration intensity cumulative rainfalls and the number of induced landslides in the intensity duration plot the critical limit is described by the equation i 19d 0 50 where i rainfall intensity expressed in mm h and d rainfall duration expressed in hours such a limit is traced to envelop 90 of the points on the graph in the ni d diagram the triggering thresholds are given by the equations ni 0 76d 0 33 and ni 4 62d 0 79 where ni normalised intensity with respect to the annual precipitation map expressed in mm h pma 100 in the article the different meaning of these thresholds is discussed finally the diagram ni ncr is proposed the triggering threshold is given by the expression ni 0 09ln ncr 0 54 where ncr is the normalised cumulative critical rainfall mm pma 100 the application of the triggering thresholds as a fundamental element in a warning system dedicated to the safeguarding of population in landslide prone areas is discussed in detail an operating procedure which is presently being verified and tested in the studied area is described

the effect of topography on earthquake ground motion a review and new results a brief review of experimental and theoretical results about the effect of topography on seismic motion shows that they are consistent only on a qualitative basis amplification at mountain tops for wavelengths comparable with mountain widths is predicted and observed but the numerical simulations often underestimate the actual observed effects we propose that this disagreement is because current models are not complex enough we therefore computed the response to incident sh waves of a set of different complex configurations that include two dimensional surface topography with or without periodic ridges and subsurface layering the results show that 1 the topographic effect in itself is difficult to isolate from other effects like surface layering and therefore the amplification on top of geomorphologically complex sites cannot be predicted by a priori estimations based solely on topography and 2 the high crest base amplification ratio observed in the field cannot usually be matched even with complex two dimensional structures with incident plane sh waves which suggests that more complex models are needed to incorporate more complex wave fields e g sv surface and three dimensional geologic configurations

environmental controls of frost cracking revealed through in situ acoustic emission measurements in steep bedrock 1 frost cracking the breakdown of rock by freezing is one of the most important mechanical weathering processes acting on earth s surface insights on the mechanisms driving frost cracking stem mainly from laboratory and theoretical studies transferring insights from such studies to natural conditions involving jointed bedrock and heterogeneous thermal and hydrological properties is a major challenge we address this problem with simultaneous in situ measurements of acoustic emissions used as proxy of rock damage and rock temperature moisture content the 1 year data set acquired in an alpine rock wall shows that 1 liquid water content has an important impact on freezing induced rock damage 2 sustained freezing can yield much stronger damage than repeated freeze thaw cycling and 3 that frost cracking occurs over the full range of temperatures measured extending from 0 down to 15 c these new measurements yield a slightly different picture than previous field studies where ice segregation appears to play an important role

extreme storm events landscape denudation and carbon sequestration typhoon mindulle choshui river taiwan we have performed the first known semicontinuous monitoring of particulate organic carbon poc fluxes and dissolved si concentrations delivered to the ocean during a typhoon sampling of the choshui river in taiwan during typhoon mindulle in 2004 revealed a poc flux of 5 00 105 t associated with a sediment flux of 61 mt during a 96 h period the linkage of high amounts of poc with sediment concentrations capable of generating a hyperpycnal plume upon reaching the ocean provides the first known evidence for the rapid delivery and burial of poc from the terrestrial system these fluxes when combined with storm derived co2 consumption of 1 65 108 mol from silicate weathering elucidate the important role of these tropical cyclone events on small mountainous rivers as a global sink of co2

timing and significance of late glacial and holocene cirque glaciation in the sierra nevada california mapping and radiocarbon dates of cirque moraines in the sierra nevada demonstrate that the last significant pre little ice age glacier advance in the range the recess peak resulted from snowline lowering roughly twice that of the matthes little ice age advance and that the recess peak advance is late pleistocene in age we mapped recess peak and matthes deposits in 64 cirques along a profile of the main sierran crest that spans the north south limits of neoglacial deposits in the range equilibrium line altitudes for the reconstructed recess peak glaciers vary greatly but coherently with those of the matthes advance the variability of both sets of deposits reflects strong topographic influences on snow accumulation and ablation patterns in their deep cirques tephrochronology and radiocarbon dates from lake sediment cores provide limits on the timing of the two advances previous work documenting the absence of a young regionally extensive tephra on matthes moraines in the central sierra demonstrates that they formed after 700 14c years bp 650 cal years bp the age of the recess peak advance has been less certain we therefore collected and dated sediment cores from lakes dammed behind terminal moraines correlating to the recess peak advance in four widely separated drainages along the sierran crest north to south south fork american river lee vining creek middle fork san joaquin river and bishop creek twenty three high precision ams radiocarbon dates on gyttja peat and macrofossils from the cores are internally consistent and demonstrate that the recess peak advance previously thought to be of late holocene age 2500 years bp ended before 11 190 70 14c years bp 13 100 85 cal years bp recess peak is therefore late pleistocene in age and probably predates the north atlantic younger dryas climatic reversal the absence of any glacial deposits on the bedrock between the recess peak and matthes deposits indicates that 1 any advance related to the younger dryas event in central california was smaller than the matthes advance 2 the matthes advance was the most extensive and possibly the only neoglacial event in the range and 3 climate in the sierra between 13 000 cal years bp and 650 cal years bp was apparently too warm and or dry to support glaciers larger than those of the little ice age other mapping indicates that the recess peak is the first significant glacier advance after retreat of tioga local late wisconsin maximum glaciers these results suggest a regionally variable climate in western north america during the younger dryas event because glaciers appear to have expanded in the canadian rockies at that time the new recess peak age limits combined with other dated lake cores indicate that the sierra was essentially deglaciated by 14 000 15 000 cal years bp 12 000 13 000 14c years bp substantially earlier than previously estimated this finding indicates that current production rates of some in situ cosmogenic nuclides calibrated on an assumed deglaciation of the range at 11 000 cal years bp 10 000 14c years bp may be systematically too high by as much as 20