extracting source characteristics and dynamics of the august 2010 mount meager landslide from broadband seismograms 1 seismic methods can substantially improve the characterization of the dynamics of large and rapid landslides such landslides often generate strong long period seismic waves due to the large scale acceleration of the entire landslide mass which according to theory can be approximated as a single force mechanism at long wavelengths i apply this theory and invert the long period seismic waves generated by the 48 5 mm3 august 2010 mount meager rockslide debris flow in british columbia using data from five broadband seismic stations 70 to 276 km from the source i obtain a time series of forces the landslide exerted on the earth with peak forces of 1 0 1011 n the direction and amplitude of the forces can be used to determine the timing and occurrence of events and subevents using this result in combination with other field and geospatial evidence i calculate an average horizontal acceleration of the rockslide of 0 39 m s2 and an average apparent coefficient of basal friction of 0 38 0 02 which suggests elevated basal fluid pressures the direction and timing of the strongest forces are consistent with the centripetal acceleration of the debris flow around corners in its path i use this correlation to estimate speeds which peak at 92 m s this study demonstrates that the time series recording of forces exerted by a large and rapid landslide derived remotely from seismic records can be used to tie post slide evidence to what actually occurred during the event and can serve to validate numerical models and theoretical methods

numerical modeling of the mount meager landslide constrained by its force history derived from seismic data we focus on the 6 august 2010 mount meager landslide that occurred in southwest british columbia canada this 48 5 mm3 rockslide that rapidly changed into a debris flow was recorded by over 25 broadband seismic stations we showed that the waveform inversion of the seismic signal making it possible to calculate the time history of the force applied by the landslide to the ground is very robust and stable even when using only data from a single station by comparing this force with the force calculated through numerical modeling of the landslide we are able to support the interpretation of seismic data made using a simple block model however our study gives different values of the friction coefficients involved and more details about the volumes and orientation of the subevents and the flow trajectory and velocity our sensitivity analysis shows that the characteristics of the released mass and the friction coefficients all contribute to the amplitude and the phase of the force despite this complexity our study makes it possible to discriminate the best values of all these parameters our results suggest that comparing simulated and inverted forces helps to identify appropriate rheological laws for natural flows we also show that except for the initial collapse peaks in the low frequency force related to bends and runup over topography changes are associated with high frequency generation possibly due to an increased agitation of the granular material involved

tropopause inversion layer seasonal and latitudinal variations and representation in standard radiosonde data and global models 1 previous publications have given information on the seasonal and latitudinal variations of the tropopause inversion layer til as seen in high resolution radiosonde data sets when soundings are averaged using the tropopause as a reference level this paper presents a more quantitative analysis of the latitudinal and seasonal structure of the til than has been given previously to do this we define the region over which the static stability relaxes from its overshoot value at the tropopause to its local minimum in the stratosphere this region is seen to increase monotonically in thickness from about 1 km at low latitudes to about 4 to 5 km at high latitudes when the seasons are defined as winter djf spring mam summer jja and fall son the transition from tropical behavior occurs a little poleward of 20 n in both djf and mam and moves to a little poleward of 30 n in jja and son somewhat surprisingly it is also shown that almost identical information about the til can be derived from standard radiosonde data for our period of analysis because of their reporting of the tropopause and other significant levels but caution needs to be used in doing this since the number of reported significant levels has varied significantly over the long term and with some distinct discontinuities finally we discuss what sort of information on the til can be obtained from global models given their relatively coarse vertical resolution

double tropopause formation in idealized baroclinic life cycles the key role of an initial tropopause inversion layer 1 recent studies have shown that double tropopauses exist in all seasons and at all longitudes in the midlatitudes as of yet the key mechanism responsible for their formation is not known in this study we explore the connection between double tropopauses and midlatitude baroclinic eddies this is investigated in the context of idealized life cycle experiments the key finding of this study is that large areas of double tropopauses form spontaneously at the nonlinear stage of the life cycle evolution provided an extratropical tropopause inversion layer is present in the balanced initial temperature profile we also show that the areas covered with double tropopauses grow as the strength of the initial tropopause inversion layer is increased without such a layer as in canonical examples of baroclinic life cycles much studied in the literature no double tropopause formation occurs in agreement with observations double tropopauses in our life cycle experiments form predominantly in areas of cyclonic flow at upper levels however the air masses that end up between the two tropopauses are found to originate from high latitudes this appears to differ from a recently published case study where the air between double tropopauses was shown to originate partly from low latitudes such a discrepancy suggests that more than one pathway may exist to advect air masses between the two tropopauses

lessons from ontake san a comparative analysis of debris avalanche dynamics abstract dynamic aspects of the long runout ontake san debris avalanche are evaluated by a comparison of several models an unsteady numerical model assumes two dimensional flow of an incompressible biviscous or newtonian fluid represented as a continuum with a free surface internal deformation of the flowing mass is considered as well as boundary resistances thus flow thinning and deposit shape as well as flow kinematics may be modeled parameters are adjusted to match observed runout with additional constraints on velocity and emplacement time with abundant constraints for ontake san from careful field investigations by japanese research teams our analysis indicates that a substantial decrease in flow resistance occurred as a function of displacement constant property models that match runout tend to overestimate the peak velocities and to underestimate the emplacement times a staged increase in mobility in both constant volume and variable volume models leads to results consistent with field data runout in a channel overflow area was also modeled qualitatively similar results have been obtained by other researchers using simple sliding block models with empirical parameters a slide block model with rational parameter selection a modified flood simulation and a multi element frictional slide model the relative merits of these models are compared the field mechanisms associated with this mobility increase with displacement are poorly understood but the question is now identified as a target for future research at debris avalanche sites and some plausible mechanisms are considered the main reason probably involves the entrainment of river water and saturated sediment leading to enhanced efficiency of fluid pressure mechanisms with undrained shear in addition progressive shearing reduced the mean particle size and angularity and the cohesion and friction and apparent viscosity of avalanche debris near the wetted perimeter hydroplaning the shearing of water films and slurries may have occurred locally

holocene history of deep seated landsliding in the north fork stillaguamish river valley from surface roughness analysis radiocarbon dating and numerical landscape evolution modeling documenting spatial and temporal patterns of past landsliding is a challenging step in quantifying the effect of landslides on landscape evolution while landslide inventories can map spatial distributions lack of dateable material landslide reactivations or time access and cost constraints generally limit dating large numbers of landslides to analyze temporal patterns here we quantify the record of the holocene history of deep seated landsliding along a 25 km stretch of the north fork stillaguamish river valley washington state usa including the 2014 oso landslide which killed 43 people we estimate the ages of more than 200 deep seated landslides in glacial sediment by defining an empirical relationship between landslide deposit age from radiocarbon dating and landslide deposit surface roughness we show that roughness systematically decreases with age as a function of topographic wavelength consistent with models of disturbance driven soil transport the age roughness model predicts a peak in landslide frequency 1 000 ybp with very few landslide deposits older than 7 000 ybp or younger than 100 ybp likely reflecting a combination of preservation bias and a complex history of changing climate base level and seismic shaking in the study area most recent landslides have occurred where channels actively interact with the toes of hillslopes composed of glacial sediments suggesting that lateral channel migration is a primary control on the location of large deep seated landslides in the valley

characterizing structural and lithologic controls on deep seated landsliding implications for topographic relief and landscape evolution in the oregon coast range usa in mountainous areas landslides regulate temporal variations in sediment production and may suppress simple linkages between topographic development and tectonic forcing rates and mechanisms of mass wasting depend on lithology bedrock structure and climatic and tectonic setting these factors tend to vary signifi cantly in active tectonic regions thus clouding our ability to predict how landsliding modulates topographic development over human and geological time scales here we use a novel dem based technique to document the distribution of large landslides in the oregon coast range ocr and quantify how they affect topographic relief we developed an automated algorithm that exploits the distinctive topographic signature specifi cally the relationship between curvature and gradient of large landslides to map their distribution within the gently folded tyee formation eocene deltaicsubmarine ramp sediments in contrast to steep and highly dissected terrain frequently identifi ed as characteristic of the ocr which exhibits steep planar sideslopes and highly curved low gradient ridgetops and valleys terrain prone to large landslides tends to have low values of both drainage density and curvature and gradient values that cluster between 0 16 and 0 44 the distribution of failure dominated terrain in our 10 000 km2 study area is infl uenced by systematic variations in sedimentary facies and bedrock structure the fraction of terrain altered by large landslides 0 1 km2 varies from 5 in the sand rich delta slope and proximal ramp facies southern section of our study area to 25 in the north distal ramp facies coincident with an increase in the thickness of siltstone beds and a decrease in the sandstone siltstone ratio local relief declines progressively northward suggesting that deep seated landsliding is sensitive to the thickness and frequency of low shearstrength siltstone beds and may serve to limit topographic development in the ocr structural controls are superimposed on facies related variations as deep seated landslides are frequently found on slopes whose downslope aspect corresponds to the bedrock dip direction for 1516 strike and dip measurements in our study area we calculated the fraction of proximal terrain 2 5 km altered by deep seated landsliding in the sand rich southern region the proportion of proximal slide dominated terrain increases modestly with bedrock dip in the silt rich northern region terrain altered by deep seated landsliding is pervasive and an increase in dip from 0 to 16 corresponds to a change in the fraction of slide prone terrain from 10 to 28 our technique for mapping large landslides has utility for hazard analysis and land management over million year time scales the progradational character of the tyee formation suggests that continued uplift and exhumation of the ocr should result in a southward propagation of slide prone silt rich distal facies as a result deep seated landsliding will become increasingly prominent and topographic relief in the central and southern ocr will progressively decline whereas spatial variability in climatic or tectonic forcing is often invoked to explain systematic variations in topographic development our results emphasize the importance of structural and intraformation lithologic controls on landsliding as such analyses linking surface processes climate tectonics and landscapes should be couched in the context of diverse geologic and topographic data

the 22 march 2014 oso landslide washington usa abstract the oso washington usa landslide occurred on the morning of saturday 22 march 2014 and claimed the lives of 43 people the landslide began within an 200 m high hillslope comprised of unconsolidated glacial and previous landslide colluvial deposits it continued as a debris avalanche debris flow that rapidly inundated a neighborhood of 35 single family residences an intense three week rainfall that immediately preceded the event most likely played a role in triggering the landslide and other factors that likely contributed to destabilization of the landslide mass include alteration of the local groundwater recharge and hydrogeological regime from previous landsliding weakening and alteration of the landslide mass caused by previous landsliding and changes in stress distribution resulting from removal and deposition of material from earlier landsliding field reconnaissance following the event revealed six distinctive zones and several subzones that are characterized on the basis of geomorphic expression styles of deformation geologic materials and the types size and orientation of vegetation seismic recording of the landslide indicate that the event was marked by several vibration generating episodes of mass movement we hypothesize that the landslide occurred in two stages with the first being a sequential remobilization of existing slide masses from the most recent 2006 landslide and from an ancient slide that triggered a devastating debris avalanche debris flow the second stage involved headward extension into previously unfailed material that occurred in response to unloading and redirection of stresses

climatological features of global multiple tropopause events 1 this study examines various climatological features related to multiple tropopause events mt events the analysis is based on the lapse rate definition of the tropopause and is performed on a radiosonde data subset taken from the integrated global radiosonde archive database the global statistics of mt events are analyzed taking into consideration both their seasonal and geographical variations our results are in moderate qualitative agreement with those of earlier studies they reinforce the analytical findings of other researchers but at the same time highlight important differences in both the number and position of the maximum occurrence of mt events we found a latitudinal band of multiple tropopause occurrence in the northern hemisphere and three centers in the southern hemisphere which coincided with identified zones of maximum cyclogenesis the climatological features of pressure temperature and vertical separation of mt events revealed the complexity of these phenomena which behave very differently according to latitude and season

how unusual is the long runout of the earthquake triggered giant luanshibao landslide tibetan plateau china abstract in the tibetan plateau active tectonic deformation triggers frequent earthquakes and giant landslides associated with active faults produce serious consequences a study of the characteristics and mechanism of a historical long runout landslide in luanshibao lsb tibetan plateau china finds a maximum sliding distance l of 3 83 km with an elevation drop h of 820 m the landslide volume v was 0 64 0 94 10 8 m 3 and it produced a long runout h l 0 21 recent surface offset along the sinistral strike slip litang dewu fault passes through the middle part of the landslide which initiated on the hanging wall of the fault geological mapping geophysical prospecting trenching and 14 c dating together indicate that the lsb landslide occurred in jointed granite ca 1980 30 ybp probably triggered by a large earthquake compilation of volume and runout distance data for this landslide and other previously published data for volcanic and nonvolcanic long runout landslides yields a composite runout length volume relation l 12 52 v 0 37 that closely predicts runout of the lsb landslide although substantial variation is noted in runout length around the central tendency

the angle of reach as a mobility index for small and large landslides the relations between the angle of reach fahrboschung and other indexes expressing the mobility of landslides and vertical drop horizontal reach and volume of landslide mass have been analyzed by means of simplified plots and regression equations results for 204 landslides of all sizes show that whatever the mechanism of motion all kinds of landslides experience a continuous reduction of the angle of reach with volume increase this reduction starts from the smallest sizes scattering in this relation is mostly due to mechanisms of motion and to both obstacles and topographic constraints on the path this synthesis indicates that small landslides less than 0 5 106 m3 in relative terms display excesses of travel distance similar to large landslides since most small landslides are not expected to develop any change in the mechanism of progression while moving the decrease in the reach angle with volume suggests that scale effects should be taken into account the angle of reach is found to be

transport and mixing in the extratropical tropopause region in a high vertical resolution gcm part i potential vorticity and heat budget analysis abstract a high vertical resolution general circulation model gcm output has been analyzed to clarify transport and mixing processes in the extratropical tropopause region the high resolution gcm with a vertical resolution of about 300 m above the extratropical upper troposphere allows simulation of fine atmospheric structures near the tropopause such as the extratropical tropopause transition layer extl and the tropopause inversion layer til the high resolution gcm realistically simulates fine thermal and dynamic structures in the extratropical tropopause region the thickness and maximum stability of the simulated til are consistent with observations the high resolution output was analyzed using a zonal mean potential vorticity pv equation to identify dominant transport processes in the extratropical tropopause region in the northern hemisphere extratropics during winter mean downward advection sharpens the pv gradient between the tropopause and 20 k below it whereas latitudinal variati

rate weakening friction characterizes both slow sliding and catastrophic failure of landslides abstract catastrophic landslides cause billions of dollars in damages and claim thousands of lives annually whereas slow moving landslides with negligible inertia dominate sediment transport on many weathered hillslopes surprisingly both failure modes are displayed by nearby landslides and individual landslides in different years subjected to almost identical environmental conditions such observations have motivated the search for mechanisms that can cause slow moving landslides to transition via runaway acceleration to catastrophic failure a similarly diverse range of sliding behavior including earthquakes and slow slip events occurs along tectonic faults our understanding of these phenomena has benefitted from mechanical treatments that rely upon key ingredients that are notably absent from previous landslide descriptions here we describe landslide motion using a rate and state dependent frictional model that incorporates a nonlocal stress balance to account for the elastic response to gradients in slip our idealized one dimensional model reproduces both the displacement patterns observed in slow moving landslides and the acceleration toward failure exhibited by catastrophic events catastrophic failure occurs only when the slip surface is characterized by rate weakening friction and its lateral dimensions exceed a critical nucleation length h h that is shorter for higher effective stresses however landslides that are extensive enough to fall within this regime can nevertheless slide slowly for months or years before catastrophic failure our results suggest that the diversity of slip behavior observed during landslides can be described with a single model adapted from standard fault mechanics treatments

unload load displacement response ratio parameter and its application in prediction of debris landslide induced by rainfall as the traditional displacement value of a landslide is very easy to be affected by rainfall it is very difficult to establish a stable and uniform destabilized criterion of landslide in terms of the displacement value so it determines that establishment of an effective and stable dynamic displacement prediction parameter is very important in forecast of the debris landslides caused by rainfall in order to determine this kind of prediction parameter this paper first completes analysis on the relationship between the destabilized mechanism of the debris landslide and the rainfall dynamic rules the relationship above shows that the periodical change value of rainfall can be taken as the dynamic unload load parameter ulp of landslide and the homologous change value of mensal landslide displacement can be taken as the stability displacement response parameter drp then on the basis of the relationship between the ulp and the stability drp of this kind of landslide the unload load displacement response ratio uldrr appraisal parameter of this kind of landslides is established in this paper finally the stability of typical debris landslides in china has been systematically studied by means of uldrr appraisal parameter and model we find that the uldrr values conform to the evolutional rule of slope deformation and instability so it has been proved that the uldrr parameter and the appraisal model are suitable and effective for prediction and evaluation of stability and evolution rule of rainfall induced landslides

extratropical tropopause transition layer characteristics from high resolution sounding data 1 accurate determination of the tropopause is important for applications such as dynamical analysis and forecasting radiative transfer calculations and the diagnosis of chemical transport in the atmosphere in this paper we examine how well the extratropical tropopause is determined in the national centers for environmental prediction high resolution global forecast system gfs model analysis over the continental united states using high resolution aircraft and radiosonde data the gfs analyses and sounding data compare well with rms differences of approximately 600 m which is comparable to the vertical resolution of the model the gfs tropopause is a good proxy in areas without in situ observations but near the subtropical jet the gfs analysis often mistakenly identifies the secondary rather than the primary tropopause we also explore an alternative method to identify the tropopause by fitting a smoothed step function to the static stability profile this new approach provides a measure of the depth of the troposphere stratosphere transition and facilitates the study of the dynamical behavior of the tropopause region in particular using the transition depth we are able to identify the statistical behavior of temperature in profiles with deep or shallow tropopause transition layers

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

comparative analysis of gps seismic and electromagnetic data on the central tien shan territory abstract on the base of the gps measured velocity field referring to the recent crust movements over sizable terrestrial areas central tien shan the strain rate tensor is evaluated as the tensor components are governed by space gradients of the velocity field the areas of the extreme values of the strain rate tensor components are shown to coincide with the highest seismic activity areas also shown is the fact that in the direction of the crust surface layer compression the deep layer electric conductivity reaches its maximum a simplest explanation of this phenomenon is proposed

analysis of long period seismic waves excited by the may 18 1980 eruption of mount st helens a terrestrial monopole long period 100 to 260 s love and rayleigh waves excited by the eruption of mount st helens on may 18 1980 and recorded by ida sro and asro stations were analyzed to determine the mechanism of the eruption the amplitude radiation patterns of both rayleigh and love waves are two lobed with a nodal direction in e5 s for rayleigh waves and in n5 e for love waves these radiation patterns preclude any double couple mechanism the radiation pattern the initial phase the relatively large amplitude ratio of love to rayleigh waves and the existence of clear nodes in the radiation patterns of fundamental mode and higher mode rayleigh waves suggest that the source is represented by an almost horizontal less than 15 from the horizontal single force pointed toward s5 w the surface wave spectra fall off very rapidly at periods shorter than 75 s suggesting a very slow source process although the details of the source time history could not be determined a smooth bell shaped time function f o s t 1 2 f o l cos t for 0 t 2 and f o s t 0 for t 2 with 75 s is considered appropriate on the basis of comparison between synthetic and observed seismograms and of the shape of the source spectrum the peak value of the force f 0 is about 10 18 dynes the tailing end of the source time function could not be resolved and some overshoot may be added the magnitude and the time history of the force can be explained by a northward landslide followed by a lateral blast observed at the time of the eruption two distinct events about 110 s apart can be identified on body wave and short period surface wave records the first event may correspond to the earthquake which triggered the landslide and the lateral blast the second event appears to correspond to a second large earthquake and explosion which took place about 2 minutes after the first earthquake

runout evaluation of the oso landslide with the material point method long runout landslides can cause significant damage and represent one of the most important problems in geotechnical engineering understanding the mechanics of the landslide runout process is impo

surface roughness dating of long runout landslides near oso washington usa reveals persistent postglacial hillslope instability establishing regional landslide chronologies is necessary to advance from hazard recognition to risk assessment and to understand the evolution of landslide prone terrain despite recent advances in landslide mapping due to the availability of high resolution lidar imagery estimating the timing of slope failures remains a challenge here we present a new integrated approach to dating landslides on a regional scale by augmenting quantitative surface roughness analysis with radiocarbon dating and numerical landscape modeling we calibrate a roughness age curve which we use to date 25 deep seated landslides in glacial sediment surrounding the catastrophic a d 2014 oso landslide along the north fork stillaguamish river in washington state usa lidar bare earth images show a high density of long runout landslides in this region using our roughness age curve we estimate an average holocene landslide frequency of 1 every 140 500 yr and show that the 2014 oso landslide was the latest event in an active history of slope failures throughout the holocene with each landslide substantial sediment is delivered to the north fork stillaguamish river driving shifts in the active channel that ultimately affect the pattern of landslides across the valley the high frequency of landslides in this area where river incision and isostatic uplift rates have dropped dramatically since peaking soon after ice retreated from the region shows that landscapes inundated by glacial sediment do not require dramatic changes in base level to remain highly unstable for tens of thousands of years

a global view of the extratropical tropopause transition layer from atmospheric chemistry experiment fourier transform spectrometer o3 h2o and co 1 the global behavior of the extratropical tropopause transition layer extl is investigated using o 3 h 2 o and co measurements from the atmospheric chemistry experiment fourier transform spectrometer ace fts on canada s scisat 1 satellite obtained between february 2004 and may 2007 the extl depth is derived using h 2 0 0 3 and co 0 3 correlations the extl top derived from h 2 0 0 3 shows an increase from roughly 1 1 5 km above the thermal tropopause in the subtropics to 3 4 km 2 5 3 5 km in the north south polar region implying somewhat weaker troposphere stratosphere transport in the southern hemisphere the extl bottom extends 1 km below the thermal tropopause indicating a persistent stratospheric influence on the troposphere at all latitudes the extl top derived from the co 0 3 correlation is lower at 2 km or 345 k 1 5 km or 335 k in the northern southern hemisphere its annual mean coincides with the relative temperature maximum just above the thermal tropopause the vertical co gradient maximizes at the thermal tropopause indicating a local minimum in mixing within the tropopause region the seasonal changes in and the scales of the vertical h 2 o gradients show a similar pattern as the static stability structure of the tropopause inversion layer til which provides observational support for the hypothesis that h 2 o plays a radiative role in forcing and maintaining the structure of the til

lateral geomorphic connectivity in a fluvial landscape system unraveling the role of confinement biogeomorphic interactions and glacial legacies abstract the rates at which sediment from the landscape is recruited to channel networks reflect lateral geomorphic connectivity and have significant implications for biophysical river systems by strongly influencing sediment supply regime such inputs control the dynamics and characteristics of the channel as well as the associated habitat and biota the main objective of this research was to disentangle the relative importance of geomorphic and biological factors which define spatial patterns in lateral connectivity by promoting or restricting bank erosion avulsions and slope failures focusing on a forested formerly glaciated mountain basin in the interior pacific northwest we combined extensive field surveys with remote sensing data lidar aerial imagery to obtain metrics representing this complex suite of landscape characteristics the interpretation of evidence yielded by correlations between these variables a regime model and qualitative observations suggest that at a multi decadal timescale between major landscape disturbances lateral connectivity patterns in sullivan creek may be to a large extent governed by a combination of biotic factors and glacial legacies in particular forest canopy metrics were key predictors of hillslope stability as well as bank and valley floor resistance suggesting a pivotal influence of root reinforcement on the other hand instream large wood abundance was closely related to channel splitting which reflects its role in promoting channel avulsions more extensive bank erosion in reaches dominated by drift deposits appeared to indicate glacial legacies furthermore a strong association between bank erosion and colluvial inputs suggested a close coupling within the channel hillslope system lateral confinement defined as the proportion of the channel length abutting against bedrock terraces fans and roads was negatively associated with channel braiding the relationships linking confinement with bank erosion and the magnitude of colluvial inputs negative and positive association respectively were relatively weak taken together findings emerging from this research suggest that better understanding of lateral geomorphic connectivity patterns in mountain river basins similar to our study site requires that both channel processes and broader biophysical landscape system be considered

application of sky view factor technique to the interpretation and reactivation assessment of landslide activity high resolution digital elevation models are crucial to the investigation of natural disasters and a variety of methods based on visualization and relief map compilations have been proposed in this study the sky view factor svf is applied to slope maps and a digital elevation model dem of the oso landslide a deadly landslide that occurred in washington state on march 22 2014 to demonstrate the effectiveness of svf enhanced relief maps in mapping and evaluating large scale or deep seated landslide hazards a procedure for combining the svf enhanced dem with slope and elevation maps is also presented then the maps are used to extract the landslide prone areas and perform a reactivation analysis of the post oso landslide using an analytic hierarchy process ahp by using the svf enhanced dem to perform the ahp assessment on multi period images we accurately evaluate hazard of the landslide for both pre and post 2014 conditions finally different visualization maps limitation and recommend parameters for generating svf relief map are presented in the paper

large landslides and deep seated gravitational slope deformations in the czech flysch carpathians new lidar based inventory abstract moderate relief landscapes such as the czech flysch outer western carpathians cowc in comparison with alpine regions are rarely subject to extensive landslide inventory mapping an understanding of landslides in such a landscape is needed because densely populated hilly landscapes in temperate zones are usually of major socio economic importance in this study we performed the first lidar based landslide mapping for the entire cowc area 7539 km2 one of the most landslide prone regions in europe by calculating various landscape and landslide metrics we infer the distribution frequency area relationships kinematics and controls of mass movements with special attention on large landslides 0 1 km2 and deep seated gravitational slope deformations dsgsds we mapped a total of 13 611 landslides of which 1357 failures are large landslides and dsgsds whereas the lower and more subdued areas in the southern part of cowc are hotspots in terms of the total number of landslides the higher and more topographically pronounced areas in the northeast are affected predominantly by large landslides and dsgsds however landslides with 0 1 km2 are widespread throughout the whole territory of cowc a discrepancy also exists in the spatial distribution of different types of landslides rock slides and dsgsds are dominant in the north east while flow type landslides are dominant in the southern lower topographic relief with claystone dominated flysch we conclude that 1 distinct geological units nappes produce landslide populations with different frequency area distributions 2 stratigraphic composition alongside the tectonic style of flysch formations control the type of landslides 3 dsgsds affect mainly slopes formed by rigid rocks sitting atop soft formations and 4 geological conditions rather than topography control distribution of large landslides and dsgsds in cowc

positive feedback and momentum growth during debris flow entrainment of wet bed sediment debris flows typically occur when intense rainfall or snowmelt triggers landslides or extensive erosion on steep debris mantled slopes the flows can then grow dramatically in size and speed as they entrain material from their beds and banks but the mechanism of this growth is unclear indeed momentum conservation implies that entrainment of static material should retard the motion of the flows if friction remains unchanged here we use data from large scale experiments to assess the entrainment of bed material by debris flows we find that entrainment is accompanied by increased flow momentum and speed only if large positive pore pressures develop in wet bed sediments as the sediments are overridden by debris flows the increased pore pressure facilitates progressive scour of the bed reduces basal friction and instigates positive feedback that causes flow speed mass and momentum to increase if dryer bed sediment is entrained however the feedback becomes negative and flow momentum declines we infer that analogous feedbacks could operate in other types of gravity driven mass flow that interact with erodible beds the mechanisms by which debris flows acquire mass and momentum as they entrain material are unclear large scale experiments suggest that the pore pressure of wet bed sediment increases as the flow moves over the bed leading to reduced friction and progressive scouring of the base

new interpretation of the reduction phenomenon in the electrical resistivity of rock masses before local earthquakes abstract based on long term observational data from the area of peter the great ridge pamir a decrease in the electrical resistivity of the rock massif before local earthquakes has been observed to explain the observed phenomenon a hypothesis has been proposed the structure of the pore space of a rock in the focal zone of an earthquake changes during the compression tension associated with earthquake preparation however the models proposed have only qualitatively interpreted the experimental data this article attempts to quantify this hypothesis based on 3d modeling of the observed electromagnetic effects it is shown that variations in the apparent resistivity are due to changes in the electrical resistivity in a narrow fault zone located at the focus of the dipole dipole sounding system the changes occur at depths of

a mechanism to explain the variations of tropopause and tropopause inversion layer in the arctic region during a sudden stratospheric warming in 2009 the mechanism to explain the variations of tropopause and tropopause inversion layer til in the arctic region during a sudden stratospheric warming ssw in 2009 was studied with the modern era retrospective analysis for research and applications reanalysis data and gps constellation observing system for meteorology ionosphere and climate cosmic temperature data during the prominent ssw in 2009 the cyclonic system changed to the anticyclonic system due to the planetary wave with wave number 2 wave2 the gps cosmic temperature data showed that during the ssw in 2009 the tropopause height in the arctic decreased accompanied with the tropopause temperature increase and the til enhancement the variations of the tropopause and til were larger in higher latitudes a static stability analysis showed that the variations of the tropopause and til were associated with the variations of the residual circulation and the static stability due to the ssw larger static stability appeared in the upper stratosphere and moved downward to the narrow region just above the tropopause the descent of strong downward flow was faster in higher latitudes the static stability tendency analysis showed that the strong downward residual flow induced the static stability change in the stratosphere and around the tropopause the strong downwelling in the stratosphere was mainly induced by wave2 which led to the tropopause height and temperature changes due to the adiabatic heating around the tropopause a pair of downwelling above the tropopause and upwelling below the tropopause due to wave2 contributed to the enhancement of static stability in the til immediately after the ssw

the interaction between the tropopause inversion layer and the inertial gravity wave activities revealed by radiosonde observations at a midlatitude station the interaction between the tropopause inversion layer til and the inertial gravity wave igw activities is first presented by using a high vertical resolution radiosonde data set at a midlatitude station boise idaho 43 57 n 116 22 w for the period 1998 2008 the tropopause based vertical coordinate is used for the til detection and for meticulously studying the igw variation around the til the broad spectral method is used for the igw extraction generally the til at the midlatitude station is stronger and thicker in winter and spring which is consistent with previous studies our study confirmed the intense interaction between the til and igw it is found that the til not only could inhibit the upward propagation of igws from below but also imply the possible excitation links between the til and igw the results also indicate that the enhanced wind shear layer just 1 km above the tropopause may result in instability and finally leads to the igw breaking and intensive turbulence subsequently the igw induced intensive turbulence leads to strong wave energy dissipation and a downward heat flux this downward heat transportation could significantly cool the tropopause while it has only negligible thermal effect on the atmosphere above the tropopause then the igw induced cooling at the tropopause makes the tropopause colder and sharper and finally forms the til these suggest besides previously proposed mechanisms that igws also contribute greatly to the formation of til which is consistent with a recent related simulation study

contrasting failure behaviour of two large landslides in clay and silt two large landslides in overconsolidated glaciolacustrine clay and silt located in river valleys in british columbia were found to be quite similar in their main aspects however their failure b

first time landslides in vashon advance glaciolacustrine deposits puget lowland u s a abstract advance glaciolacustrine qglv deposits from the last continental glaciation are widespread in the densely populated puget lowland and are prone to shallow landsliding much less frequently in historic time new landslides propagate deeply within intact qglv deposits the exceptional volume and highly mobile nature of the 22 march 2014 state route 530 oso landslide generated considerable uncertainty and public concern about the likelihood for similar deep seated failures initiating from most any slope where these deposits crop out the primary study objectives are to utilize geotechnical data from the small data set of available published and public domain investigations to characterize in general terms hydrogeologic geotechnical and geomorphic factors and their relative contribution to initiating deep seated landslides within intact qglv deposits and to inform future hazard and risk assessments for first time landslides within these deposits qglv deposits are overconsolidated very stiff to hard laminated to massive silt and clay shear strength is anisotropic with cohesion being a significant component of bedding parallel strength and friction dominating strength perpendicular to bedding hydraulic conductivity is likely also anisotropic multi year records of pore pressures within qglv deposits show no to minor seasonal flux only minor pore pressure responses to multi day to multi week episodes of heavy precipitation have been detected back analyses using limit equilibrium methods and peak anisotropic strength under drained conditions demonstrate initial stability of the slopes instability occurs near the fully softened strength we conclude that over the long term loss of cohesive strength rather than hydroclimatic pore pressure response is the more important contributor to diminishing stability and in some cases initiation of first time landslides in qglv deposits the shape and location of the slide surface is strongly influenced by strength anisotropy and stress state sliding surfaces developed near the basal contact of the qglv deposits in all of the five studied landslides higher stress states associated with increasing sequence thickness of the landslide masses decrease stability the length of the basal slide surface and thus the aspect ratio of the landslide mass appears to increase proportionally with sequence thickness of the landslide mass

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

seismic and acoustic signatures of surficial mass movements at volcanoes abstract surficial mass movements such as debris avalanches rock falls lahars pyroclastic flows and outburst floods are a dominant hazard at many volcanoes worldwide understanding these processes cataloging their spatio temporal occurrence and detecting tracking and characterizing these events would advance the science of volcano monitoring and help mitigate hazards seismic and acoustic methods show promise for achieving these objectives many surficial mass movements generate observable seismic and acoustic signals and many volcanoes are already monitored significant progress has been made toward understanding modeling and extracting quantitative information from seismic and infrasonic signals generated by surficial mass movements however much work remains in this paper we review the state of the art of the topic covering a range of scales and event types from individual rock falls to sector collapses we consider a full variety of volcanic settings from submarine to subaerial shield volcano to stratovolcano finally we discuss future directions toward operational seismo acoustic monitoring of surficial mass movements at volcanoes

simple scaling of catastrophic landslide dynamics catastrophic landslides involve the acceleration and deceleration of millions of tons of rock and debris in response to the forces of gravity and dissipation their unpredictability and frequent location in remote areas have made observations of their dynamics rare through real time detection and inverse modeling of teleseismic data we show that landslide dynamics are primarily determined by the length scale of the source mass when combined with geometric constraints from satellite imagery the seismically determined landslide force histories yield estimates of landslide duration momenta potential energy loss mass and runout trajectory measurements of these dynamical properties for 29 teleseismogenic landslides are consistent with a simple acceleration model in which height drop and rupture depth scale with the length of the failing slope

fine scale structure of the extratropical tropopause region 1 a vertically high resolved climatology of the thermal and wind structure of the extratropical tropopause region is presented the climatology is based on data from 80 u s radiosonde stations covering the period 1998 2002 time averages for each radiosonde station are computed using the tropopause as a common reference level for all vertical profiles within the mean a strong inversion at the tropopause in the mean vertical temperature gradient is uncovered that is temperature strongly increases with altitude within the lowermost stratosphere this tropopause inversion layer exists on average throughout the investigated extratropics about 30 n to 70 n accordingly the static stability parameter shows considerably enhanced values within the lowermost extratropical stratosphere compared to typical extratropical stratospheric values further aloft conventional averages are not able to capture the tropopause inversion layer mean profiles of the horizontal wind show behavior qualitatively corresponding to thermal wind balance winter and summer exhibit distinctly different climate states in the extratropical tropopause region an approximated potential vorticity is considered and found to be close to well mixed within the troposphere as well as within the tropopause inversion layer this suggests the view of the tropopause inversion layer as representing a dynamically active atmospheric layer some potential implications are discussed

large landslides and their effect on sediment flux in south westland new zealand landslides and runoff are dominant erosional agents in the tectonically active alpine south westland area of new zealand characterized by high uplift rates and extreme orographic precipitation despite a high density of shallow debris slides and flows the geomorphic imprints of deep seated bedrock failures are dominant and persistent over 50 large 1k m 2 landslides comprising rock slide avalanches complex rotational and rock block slides wedge failures and deep seated gravitational slope deformation were detected on air photos and shaded relief images major long term impacts on alpine rivers include 1 forced alluviation upstream of landslide dams 2 occlusion of gorges and triggering of secondary riparian landslides and 3 diversion of channels around deposits to form incised meandering gorges remnants of large prehistoric i e pre 1840 landslide deposits possibly represent the low frequency in terms of total area affected yet dominant end of the spectrum of mass wasting in the western southern alps this is at odds with high erosion rates in an active erosional landscape large landslides appear to have dual roles of supplying and retaining sediment the implications of these roles are that 1 previous models of shallow landslide derived sediment flux need to be recalibrated and 2 geomorphic effects of earthquake induced landsliding may persist for at least 10 2 years copyright 2005 john

radiocarbon age constraints on rates of advance and retreat of the puget lobe of the cordilleran ice sheet during the last glaciation abstract calibrated radiocarbon dates of organic matter below and above till of the last fraser glaciation provide limiting ages that constrain the chronology and duration of the last advance retreat cycle of the puget lobe in the central and southeastern puget lowland seven dates for wood near the top of a thick proglacial delta have a weighted mean age of 17 420 90 cal yr b p which is the closest limiting age for arrival of the glacier near the latitude of seattle a time distance curve constructed along a flowline extending south from southwestern british columbia to the central puget lowland implies an average glacier advance rate of ca 135 m yr the glacier terminus reached its southernmost limit ca 16 950 yr ago and likely remained there for ca 100 yr in the vicinity of seattle where the glacier reached a maximum thickness of 1000 m ice covered the landscape for ca 1020 yr postglacial dates constraining the timing of ice retreat in the central lowland are as old as 16 420 cal yr b p and show that the terminus had retreated to the northern limit of the lowland within three to four centuries after the glacial maximum the average rate of retreat was about twice the rate of advance and was enhanced by rapid calving recession along flowline sectors where the glacier front crossed deep proglacial lakes

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

the perfect debris flow aggregated results from 28 large scale experiments 1 aggregation of data collected in 28 controlled experiments reveals reproducible debris flow behavior that provides a clear target for model tests in each experiment 10 m3 of unsorted water saturated sediment composed mostly of sand and gravel discharged from behind a gate descended a steep 95 m flume and formed a deposit on a nearly horizontal runout surface experiment subsets were distinguished by differing basal boundary conditions 1 versus 16 mm roughness heights and sediment mud contents 1 versus 7 percent dry weight sensor measurements of evolving flow thicknesses basal normal stresses and basal pore fluid pressures demonstrate that debris flows in all subsets developed dilated coarse grained high friction snouts followed by bodies of nearly liquefied finer grained debris mud enhanced flow mobility by maintaining high pore pressures in flow bodies and bed roughness reduced flow speeds but not distances of flow runout roughness had these effects because it promoted debris agitation and grain size segregation and thereby aided growth of lateral levees that channelized flow grain size segregation also contributed to development of ubiquitous roll waves which had diverse amplitudes exhibiting fractal number size distributions despite the influence of these waves and other sources of dispersion the aggregated data have well defined patterns that help constrain individual terms in a depth averaged debris flow model the patterns imply that local flow resistance evolved together with global flow dynamics contradicting the hypothesis that any consistent rheology applied we infer that new evolution equations not new rheologies are needed to explain how characteristic debris flow behavior emerges from the interactions of debris constituents

formation and maintenance of the extratropical tropopause by baroclinic eddies numerical simulations in a simple atmospheric model show that a realistic extratropical tropopause structure marked by a strong change both in meteorological variables such as lapse rate and in transport characteristics may be achieved solely through the stirring effects of baroclinic eddies acting against a smooth thermal relaxation the flow self organizes to give a transport structure that has a sharp transition in the vertical below the transition level the eddies stir across entire isentropic surfaces the transition level corresponds to the extratropical tropopause height above the transition level there is a midlatitude transport barrier corresponding to the subtropical transport barrier in the real atmosphere with eddy stirring on poleward and equatorward sides similar self organizing mechanisms are likely to be relevant in the stratosphere and in oceanic flows

active movement of the cascade landslide complex in washington from a coherence based insar time series method abstract we used interferometric synthetic aperture radar insar data from the alos 1 satellite to investigate the active movement of landslides along the columbia river gorge from 2007 2011 to increase the spatial extent of the deformation signal we developed a coherence based small baseline subset sbas method and derived the time series of the landslide movement we find no significant movement on the previously mapped washougal sakamania oregon shore and wind mountain landslides however we document the slow movement of the redbluff landslide which is part of the cascade landslide complex the insar data reveal up to approximately 25 cm of line of sight displacement over the 4 year observation period the redbluff landslide is seasonally activated with accelerated movement observed during the early winter of each year the amplitude of the seasonal signal is variable from year to year with the greatest movement observed in early winter of 2009 and 2011 to assess the triggering mechanisms we compared the displacement time series data with local precipitation data the deformation correlated well with precipitation implying the slow movement is controlled by rainfall that infiltrates to the base of the slide

gps velocity field for the tien shan and surrounding regions 1 measurements at 400 campaign style gps points and another 14 continuously recording stations in central asia define variations in their velocities both along and across the kyrgyz and neighboring parts of tien shan they show that at the longitude of kyrgyzstan the tarim basin converges with eurasia at 20 2 mm yr nearly two thirds of the total convergence rate between india and eurasia at this longitude this high rate suggests that the tien shan has grown into a major mountain range only late in the evolution of the india eurasia collision most of the convergence between tarim and eurasia within the upper crust of the tien shan presumably occurs by slip on faults on the edges of and within the belt but 1 3 mm yr of convergence is absorbed farther north at the dzungarian alatau and at a lower rate with the kazakh platform to the west the tarim basin is thrust beneath the tien shan at 4 7 mm yr with respect to eurasia the ferghana valley rotates counterclockwise at 0 7 myr 1 about an axis at the southwest end of the valley thus gps data place a bound of 4 mm yr on the rate of crustal shortening across the chatkal and neighboring ranges on the northwest margin of the ferghana valley and they limit the present day slip rate on the right lateral talas ferghana fault to less than 2 mm yr gps measurements corroborate geologic evidence indicating that the northern margin of the pamir overthrusts the alay valley and require a rate of at least 10 and possibly 15 mm yr

neotectonics and geodynamics of mountain systems of central asia abstract neotectonic structure and geodynamics of intracontinental mountain belts of central asia are examined from the viewpoint that in the base mountain building processes are very different processes the nature of those processes the manner of their interactions and the intensities of structural manifestations vary from one region to another in different layers of the lithosphere and in time

insights into rock ice avalanche dynamics by combined analysis of seismic recordings and a numerical avalanche model 1 rock ice avalanches larger than 1 106 m3 are high magnitude low frequency events that may occur in all ice covered high mountain areas around the world and can cause extensive damage if they reach populated regions the temporal and spatial evolution of the seismic signature from two events was analyzed and recordings at selected stations were compared to numerical model results of avalanche propagation the first event is a rock ice avalanche from iliamna volcano in alaska which serves as a natural laboratory with simple geometric conditions the second one originated on aoraki mt cook new zealand southern alps and is characterized by a much more complex topography a dynamic numerical model was used to calculate total avalanche momentum total kinetic energy and total frictional work rate among other parameters these three parameters correlate with characteristics of the seismic signature such as duration and signal envelopes while other parameters such as flow depths flow path and deposition geometry are well in agreement with observations the total frictional work rate shows the best correlation with the absolute seismic amplitude suggesting that it may be used as an independent model evaluation criterion and in certain cases as model calibration parameter the good fit is likely because the total frictional work rate represents the avalanche s energy loss rate part of which is captured by the seismometer deviations between corresponding calculated and measured parameters result from site and path effects which affect the recorded seismic signal or indicate deficiencies of the numerical model the seismic recordings contain additional information about when an avalanche reaches changes in topography along the runout path and enable more accurate velocity calculations the new concept of direct comparison of seismic and avalanche modeling data helps to constrain the numerical model input parameters and to improve the understanding of rock ice avalanche dynamics

three dimensional seismic velocity structure of the crust beneath the central tien shan kyrgyzstan implications for large and small scale mountain building abstract the central tien shan kyrgyzstan is located approximately 2000 km from the main collisional suture between india and eurasia and is sandwiched between the kazakh shield to the north and the tarim basin to the south a three dimensional 3 d seismic velocity structure of the crust beneath the central tien shan was estimated to a depth of 50 km by means of seismic tomography using arrival time data of p and s waves from local earthquakes recorded by a temporary seismic network of the tien shan during 1998 2000 velocity structure images show a good correlation with the subsurface geology at shallow depths a low velocity zone is distributed beneath the basins probably due to the cenozoic deposition whereas a high velocity zone is visible beneath the mountain ranges likely due to paleozoic crystalline basement rocks at the surface layer results obtained at greater depths revealed the following features 1 a low velocity zone is clearly observed in the middle to lower crust and is probably caused by melt and or fluids conveyed through the flow of mantle upwelling 2 both north dipping and south dipping low velocity zones were imaged at locations where the kazakh shield and the tarim basin underthrust beneath the tien shan respectively and are probably caused by mantle materials somehow being intruded into the crust 3 the lateral variation of high and low velocity zones seen in the middle to lower crust beneath basins and surrounding mountain ranges respectively seems to be caused by melt and or fluids vertically penetrated and or laterally spread all these findings suggest that in process northward shortening and crustal thickening owing to collision and mantle convective motion i e upwelling and as a consequence partial melting are work horses in the mountain building beneath the tien shan

objective delineation of lahar inundation hazard zones a new method of delineating lahar hazard zones in valleys that head on volcano flanks provides a rapid objective reproducible alternative to traditional methods the rationale for the method derives from scaling analyses of generic lahar paths and statistical analyses of 27 lahar paths documented at nine volcanoes together these analyses yield semiempirical equations that predict inundated valley cross sectional areas a and planimetric areas b as functions of lahar volume v the predictive equations a 0 05v 2 3 and b 200v 2 3 provide all information necessary to calculate and plot in

dynamical formation of an extra tropical tropopause inversion layer in a relatively simple general circulation model 1 the key factors contributing to the formation and maintenance of the recently discovered extra tropical tropopause inversion layer are presently unclear in this study it is shown that such a layer can form as a consequence of the turbulent dynamics of synoptic scale baroclinic eddies alone in the absence of explicitly parameterized small scale radiative convective processes a simple general circulation model initialized from a state of rest and driven with idealized forcings is found to spontaneously develop an inversion layer above the tropopause under a wide variety of parameter choices and model resolutions furthermore such a model is able to capture qualitatively both the latitudinal and in part the seasonal dependence of the observed tropopause inversion layer however the inability of our simple model to capture some detailed quantitative features strongly suggests that other physical processes beyond balanced synopticscale dynamics are likely to play an important role citation son s w and l m polvani 2007 dynamical formation of an extra tropical tropopause inversion layer in a relatively simple general circulation model geophys res lett 34 l17806 doi 10 1029 2007gl030564

oso washington landslide of march 22 2014 dynamic analysis abstractthis paper describes and explains the spectacular mobility of the 2014 oso landslide which was the cause of its fatal consequences a geomorphic interpretation of the site conditions is us

liquefaction flowslides in rocky mountain coal mine waste dumps over the past 25 years there have been a large number of long runout flowslides from rocky mountain coal mine waste dumps the waste dumps are constructed as end dumped fills with an angle of repos

the tropopause inversion layer in models and analyses recent high resolution radiosonde climatologies have revealed a tropopause inversion layer til in the extratropics temperature strongly increases just above a sharp local cold point tropopause here it is asked to what extent a til exists in current general circulation models gcms and meteorological analyses only a weak hint of a til exists in ncep ncar reanalysis data in contrast the canadian middle atmosphere model cmam a comprehensive gcm exhibits a til of realistic strength however in data assimilation mode cmam exhibits a much weaker til especially in the southern hemisphere where only coarse satellite data are available the discrepancy between the analyses and the gcm is thus hypothesized to be mainly due to data assimilation acting to smooth the observed strong curvature in temperature around the tropopause this is confirmed in the reanalysis where the stratification around the tropopause exhibits a strong discontinuity at the start of the satellite era

case study oso washington landslide of march 22 2014 material properties and failure mechanism abstractthis paper describes investigation testing analysis and slope history used to determine the two phase failure mechanism involved in the 2014 landslide near oso washington the first pha

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

moraines and marls giant landslides of the lago pueyrredon valley in patagonia argentina abstract giant catastrophic landslides 108 m3 dot the formerly glaciated mountain forelands of the eastern patagonian andes from geomorphic mapping sedimentological logs and radiocarbon dating we infer the emplacement kinematics and approximate timing of giant landslides in moraines and other glacial deposits in the lago pueyrredon valley lpv argentina for the first time we report in detail examples of giant low gradient landslides with hummocky lobes derived from unconsolidated glacial deposits and weak bedrock we find that at least 4 5 km3 of debris and weak bedrock were mobilized by slope failures in an area of 500 km2 since the last glacial maximum lgm 25 18 ka nearly 90 of this landslide volume originated along the shores of or as subaqueous failures in a postglacial moraine dammed meltwater lake the larger landslides 1 km3 detached from moraines fringing the lake whereas other landslides displaced glacial and lake deposits either on the paleolake bed or in a river gorge that was cut upon drainage of the glacial lake sequences of till glaciofluvial and glaciolacustrine deposits overlying weak early miocene marlstone are mostly conducive to major landslides in the lpv cross cutting relationships indicate that largest landslides in the area originated during rapid glacial lake level drops distribution and internal structure of hummocks within landslide lobes suggest that these landslides were emplaced as catastrophic debris avalanches it suggests that giant catastrophic landslides in the glacier forelands of patagonia can result from layered weak rocks changes in meltwater lake levels and possibly as a consequence of strong earthquakes linked to rapid post glacial rebound following the retreat of the patagonian ice sheet pis

the extratropical tropopause inversion layer global observations with gps data and a radiative forcing mechanism global characteristics of the extratropical tropopause inversion layer identified in radiosonde observations by birner are studied using high vertical resolution temperature profiles from gps radio occultation measurements the gps data are organized according to the height of the thermal tropopause in each profile and a temperature inversion layer above the tropopause with an average magnitude of 3 5 k is found to be a ubiquitous climatological feature the gps data show that the inversion layer is present for all seasons in both hemispheres spanning the subtropics to the pole and there is not strong longitudinal structure dependence of the inversion layer on upper troposphere vorticity is studied while anticyclones exhibit a substantially stronger inversion than cyclones as expected from balanced dynamics the inversion is evident for all circulation types radiative transfer calculations indicate that strong gradients in both ozone and water vapor near the tropopause contribute to the inversion significant absorption of both longwave and shortwave radiation by ozone occurs warming the region above the tropopause water vapor near and immediately above the tropopause contributes to cooling effectively enhancing the inversion

relatively recent construction of the tien shan inferred from gps measurements of present day crustal deformation rates the tien shan a high seismically active intracontinental mountain belt 1 000 2 000 km north of the himalaya has grown as a result of india s collision with asia1 the crustal shortening 200 50 km refs 2 3 and thickening that gave rise to the tien shan accommodates only a small fraction of india s total penetration into asia 2 000 3 000km and the temporal relationship of deformation in this belt to the india asia collision remains unclear here we report geodetic measurements of the tien shan using the global positioning system gps that indicate that the current crustal shortening rate is nearly half of india s convergence rate with eurasia in this area4 we infer a total shortening rate for the tien shan of 20 mm yr 1 which is approximately twice that inferred previously from the extrapolation of slip rates in the holocene3 and earthquake induced displacements during this century5 suggesting that the rate of mountain building in this region has accelerated several fold since the onset of collision 50 55 myr ago6 7 if as we argue the current shortening rate can be extrapolated to geological timescales then our results suggest that most of the tien shan has been constructed during the past 10 myr perhaps in response to an increased horizontal force following an abrupt rise of the tibetan plateau8 9

characteristics of the subtropical tropopause region based on long term highly resolved sonde records over tenerife 1 this study examines the structure of the subtropical tropopause region over tenerife the canary islands spain 28 n 16 w based on a 20 year 1992 2011 ozonesonde data and european center for medium range weather forecasts era interim potential vorticity pv and zonal wind speed reanalysis high resolution vertical profiles allowed a detailed description of the subtropical tropopause break and the associated subtropical jet stream stj where models fail to properly simulate the upper troposphere lower stratosphere utls the subtropical utls is revealed as a complex atmospheric region with a thickness 8 km which is examined through the analysis and evaluation of four different tropopause definitions thermal tt cold point ozone ot and dynamical dt tropopauses a novel method to determine the dt based on the vertical gradient of lait s modified pv is presented and the concept of a second dt has been introduced for the first time monthly climatologies of tropopause height and potential temperature are calculated for double and single tropopause events the 14 3 km height level is used to differentiate between tropical and extratropical utls regimes intimately linked to the position of the stj there is fairly good consistency between all the defined tropopauses under the double tropopause scheme except in spring when the ot is observed at lower levels due to frequent baroclinic instabilities in the upper troposphere as concerns to single tropopause events the same pattern is found from april to june reflecting the influence of analogous processes during these months in winter altitude differences between ot dt and tt resulted from poleward stj excursions forced by blocking systems over the north atlantic analysis of the tropopause inversion layer showed distinctive features for tropical and midlatitude tropopauses

effects of soil aggregates on debris flow mobilization results from ring shear experiments abstract rates and styles of landslide motion are sensitive to pore water pressure changes caused by changes in soil porosity accompanying shear deformation soil may either contract or dilate upon shearing depending upon whether its initial porosity is greater or less respectively than a critical state porosity attained after sufficiently high strain we observed complications in this behavior however during rate controlled 0 02 m s 1 ring shear experiments conducted on naturally aggregated dense loamy sand at low confining stresses 10 6 and 40 kpa the aggregated soil first dilated and then contracted to porosities less than initial values whereas the same soil with its aggregates destroyed monotonically dilated we infer that aggregates persisted initially during shear and caused dilation before their eventual breakdown enabled net contraction an implication of this contraction demonstrated in experiments in which initial soil porosity was varied is that the value of porosity distinguishing initially contractive from dilative behavior can be significantly larger than the critical state porosity which develops only after disaggregation ceases at high strains in addition post dilative contraction may produce excess pore pressures thereby reducing frictional strength and facilitating debris flow mobilization we infer that results of triaxial tests which generally produce strains at least a factor of 4 smaller than those we observed at the inception of post dilative contraction do not allow soil contraction to be ruled out as a mechanism for debris flow mobilization in dense soils containing aggregates