regional scale co seismic landslide assessment using limit equilibrium analysis abstract traditionally regional assessment of seismic slope stability has been done using the infinite slope rigid sliding block analysis a major disadvantage of this approach is the resulting overestimation of the critical acceleration of the slope due to the underlying assumption of a predefined slope failure plane and consequently the underestimation of hazard areas prone to sliding in this paper we present a modified approach for assessing seismic slope instabilities using a model based on limit equilibrium analysis and circular slip surfaces with no restriction to any predefined slope failure plane for this purpose we conduct a parametric study to identify the relationship between the critical acceleration of the slope the slope angle and the slope shear strength parameters we model typical slopes in the rocscience software slide using bishop s limit equilibrium method to identify the critical accelerations that corresponds to a failure plane with factor of safety equal to one the critical accelerations were plotted against the variables in the parametric study and the best fit equations were obtained the proposed approach was developed for global application but it was tested using the well documented co seismic landslide database of the 1994 northridge ca earthquake the predicted sliding areas were compared to the inventory of landslides that were triggered in the val verde region in los angeles by the earthquake qualitative and quantitative assessments of the proposed model clearly show its advantages in predicting potential sliding areas

anti plane responses of acceleration by a shallow hill next to an alluvial valley abstract this study proposed a hybrid method combining finite element method fem and a wave function based on the lamb series in conjunction with modified transfinite interpolation for use in examining surface accelerations on a semi elliptical hill subjected to shear horizontal sh waves of various dimensionless frequencies at various incident angles the case topography included a semi elliptical hill of fixed height adjacent to a semi elliptical alluvial valley of variable depth ehav differences in site effects between ehav and a single semi elliptical hill or a semi elliptical alluvial valley were investigated as a function of the modified transmissibility tr variations in tr associated with clearly revealed the resonance frequencies rfs associated with an elevated probability of landslides our simulation results revealed a larger number of rfs form in hills adjacent to av than in isolated hill this study proposes a systematic approach for the analysis of site effects of ehav focusing on the identification of potential landslides due to seismic waves excitation

spatial distribution of landslides triggered by the 2008 ms 8 0 wenchuan earthquake china abstract the ms 8 0 wenchuan earthquake of may 12 2008 is one of the most disastrous earthquakes in china the earthquake triggered tens of thousands of landslides over a broad area including shallow disrupted landslides rock falls deep seated landslides and rock avalanches some of which buried large sections of some towns and dammed the rivers the purpose of this study is to investigate correlations between the occurrence of landslides with geologic and geomorphologic conditions and seismic parameters over 56 000 earthquake triggered landslides with a total area of 811 km 2 are interpreted using aerial photographs and remote sensing images taken following the earthquake the spatial distribution of these landslides is analyzed statistically using both landslide point density lpd defined as the number of landslides per square kilometer and landslide area density lad the percentage of the area affected by landslides to determine how the occurrence of landslides correlates with distance from the epicenter distance from the major surface rupture seismic intensity and peak ground acceleration pga slope angle slope aspect elevation and lithology it is found that both lad and lpd have strong positive correlations with slope steepness distance from the major surface rupture and seismic intensity and that pre sinian schist and cambrian sandstone and siltstone intercalated with slate have the most concentrated landslide activities followed by the permian limestone intercalated with shale and devonian limestone statistical analyses also indicate that the major surface rupture has influence on the spatial distribution of landslides because lad and lpd are relatively higher on the hanging wall than on the footwall however the correlation between the occurrence of landslides with distance from the epicenter of the earthquake is complicated rather than a relatively simple negative correlation as found from other reported cases of earthquakes this is possibly due to complicated rupture processes of the earthquake

development of a loess mudstone landslide in a fault fracture zone a landslide occurred on the morning of december 16 2013 in liujiabao village tianshui city gansu province china the 260 000 m3 of landslide material traveled a distance of 190 m downslope and damaged a village road and several farmhouses before it stopped on the middle of the slope these landslide materials are still threatening the lives and property of people in the downslope residential areas a field survey revealed that this landslide was strongly affected by the geological setting six normal faults that extend from east to west developed in the neogene mudstone of this region these faults form a fault fracture zone with a width of 80 m the authors performed a detailed investigation of the geological features of these six normal faults and their spatial and faulting relationships to the landslide were examined finally the evolutionary progress of the loess mudstone landslide controlled by the fault fracture zone is discussed

landslides induced by the wenchuan earthquake and the subsequent strong rainfall event a case study in the beichuan area of china abstract the wenchuan earthquake on may 12 2008 triggered massive landslides and a subsequent strong rainfall prompted the development of new landslides as well as the reactivation of some pre existing landslides the highest seismic intensity zone of the wenchuan earthquake in beichuan china was selected as a case study to analyze the influence of the earthquake and the subsequent heavy rains on landslide evolution we selected this study area 414 km 2 since it was close to the coseismic surface rupture and because it suffered strong ground motion based on the interpretation of high resolution aerial photographs and remote sensing imagery combined with field investigation 40 pre earthquake landslides and 2221 coseismic landslides were identified with total landslide areas of 2 68 km 2 and 30 81 km 2 respectively there were 134 large over 50 000 m 2 co seismic landslides that covered a surface area of 15 54 km 2 and represented approximately 50 4 of the total area of the co seismic landslides the coseismic landslides were mainly located on the hanging wall of the causative fault and on the steep valley sides of the jian river and its tributaries a strong rainfall event occurred four months after the wenchuan earthquake and induced 969 new landslides which covered a 6 90 km 2 area and enlarged 169 existing landslides 2 48 km 2 the landslides were identified in spot5 images ultimately we found that earthquake tremors and the subsequent rainstorm severely disturbed the surface strata resulting in a large number of landslides

distribution pattern of earthquake induced landslides triggered by the 12 may 2008 wenchuan earthquake abstract this paper presents the preliminary results of an extensive study of the mapping the distribution of landslides triggered by the wenchuan earthquake in sichuan province china on 12 may 2008 an extensive landslide interpretation was carried out using a large set of optical high resolution satellite images e g aster alos cartosat 1 spot 5 and ikonos as well as air photos for both the pre and post earthquake situation landslide scarps were mapped as points using multi temporal visual image interpretation taking into account shape tone texture pattern elevation and ridge and valley orientation nearly 60 000 individual landslide scarps were mapped the landslide distribution map was compared with the inventory map that was prepared directly after the earthquake which contains about 11 000 individual landslide points through the calculation of normalized landslide isopleths maps remarkable differences were observed as the earlier inventory mapping did not consider the pre earthquake situation and did not consider all individual landslides as part of the landslide inventory landslides were identified that had blocked the drainage and had formed landslide dams the landslide distribution was compared with a number of aspects such as the seismic parameters distance to epicenter distance to fault rupture co seismic fault geometry and co seismic slip distribution and geology the most remarkable correlation found was with the co seismic slip distribution and the fault geometry landslide distribution in the section of the fault that had mainly a thrust component with low angle fault plane was found to be much higher than the sections that had steeper fault angles and a major strike slip component

comparison of earthquake environmental effects and esi intensities for recent seismic events in different tectonic settings sichuan sw china and central apennines italy abstract in the framework of a bilateral cooperation project between the geological surveys of china and italy the geological effects of six strong to moderate earthquakes occurred in sichuan china 2008 2013 2017 and in central apennines italy 2009 24 aug and 30 oct 2016 were compared the main aim was to test the applicability and effectiveness of the esi intensity scale in areas characterized by different tectonic settings compressive and strike slip vs extensional and also by different local conditions e g geomorphologic lithologic and climatic that can influence the occurrence and size of individual eees at a specific site in general for all these earthquakes the distribution and size of geological effects resulted proportional to the earthquake severity however notably the earthquakes of moderate magnitude i e between 6 and 7 showed i well evident surface faulting only in the extensional domain of the central apennines while poor or no evidence was found for reverse and strike slip events sichuan ii a strong influence on the occurrence of secondary effects from site conditions e g lithology elevation slope angle soil cover climate those that typically control for example the susceptibility to landsliding based on the esi intensity scale epicentral and local intensities were estimated by means of the surface faulting extent and of the total area of secondary effects mainly landslides the comparison with the damage or pga based intensities has confirmed the efficacy of the esi scale to improve the portrait of the earthquake and to pinpoint areas of enhanced hazard especially those related to slope failures and liquefaction this work is also a substantial contribution to the future revision of the esi scale in particular for reverse faulting earthquakes

analysis of antarctic peninsula glacier frontal ablation rates with respect to iceberg melt inferred variability in ocean conditions marine terminating glaciers on the antarctic peninsula ap have retreated accelerated and thinned in response to climate change in recent decades ocean warming has been implicated as a trigger for these changes in glacier dynamics yet little data exist near glacier termini to assess the role of ocean warming here we use remotely sensed iceberg melt rates seaward of two glaciers on the eastern and six glaciers on the western ap from 2013 to 2019 to explore connections between variations in ocean conditions and glacier frontal ablation we find iceberg melt rates follow regional ocean temperature variations with the highest melt rates mean 10 cm d 1 at cadman and widdowson glaciers in the west and the lowest melt rates mean 0 5 cm d 1 at crane glacier in the east near coincident glacier frontal ablation rates from 2014 to 2018 vary from 450 m a 1 at edgeworth and blanchard glaciers to 3000 m a 1 at seller glacier former wordie ice shelf tributary variations in iceberg melt rates and glacier frontal ablation rates are significantly positively correlated around the ap spearman s 0 71 p value 0 003 we interpret this correlation as support for previous research suggesting submarine melting of glacier termini exerts control on glacier frontal dynamics around the ap

mass movements along a rapidly uplifting river valley an example from the upper jinsha river southeast margin of the tibetan plateau because of the rapid uplift of the tibetan plateau since the middle and late pleistocene the surrounding mountainous areas of the tibetan plateau also show a rapid uplift trend the study area is located in the upper reaches of the jinsha river southeastern tibetan plateau tectonically the study area is located in the eastern segment of the jinshajiang suture zone which is the weak belt of the lithosphere affected by the rapid uplift steep slopes are formed by the rapid vertical down cutting of rivers in the studied reach under the sustained action of the gravitational field the deformation and failure of slopes readily occur to better formulate development and risk mitigation plans a mass movement inventory map at the scale of 1 50 000 was prepared for the 100 km long reach a total of 247 mass movements of different types sizes and relative ages were mapped via image interpretation and detailed field survey the statistical analysis of their spatial distributions was performed using two relative concentration indexes the correlations between the spatial distribution and six common factors were analyzed elevation slope angle slope aspect lithology active fault and river system the geomorphological survey shows that the mass movements locally play an important role in the present day landscape evolution in addition the geomorphic features indicate that the mapped giant landslides can be classified as very old landslides and they very likely occurred under a different morphoclimatic environment than that of the present

effects of sampling intensity and non slide slide sample ratio on the occurrence probability of coseismic landslides abstract due to the influence of sampling strategy the resulting probability of landslides using logistic regression lr can deviate considerably from the actual areal percentage of coseismic landslides this study used the landslides data of the 2013 lushan china earthquake to further address this issue based on the bayesian theory we proposed a sampling method that selects the sliding samples and non sliding samples based on the ratio of the stable area to the landslide area using this method we tested 15 values of sampling intensities 1 10 20 30 40 50 60 70 80 90 100 200 500 1000 and 2000 grid cell km 2 and 12 values of non sliding sliding sample ratios 1 5 10 25 50 75 100 125 150 175 200 and 228 for the analysis of the lr model ten factors were considered in this analysis including elevation slope gradient aspect the topographic wetness index twi peak ground acceleration pga distance to the epicenter distance to rivers distance to roads lithology and annual precipitation in terms of these 15 sampling intensities and 12 sample ratios the samples were trained 200 and 150 times respectively using the lr model yielding 4800 predicted pictures of potential landslides in the study area the results show that different sampling intensities have a certain effect on the total predicted landslide area the higher the intensity of the samples the more stable the prediction results especially when the sampling intensity reaches 1000 grid cell km 2 the total area of the predictive model is about 17 1 km2 which is close to the real area with 17 16 km2 with a difference within 2 different ratios of non slide slide sample greatly affect the occurrence probability of coseismic landslides when the ratio is 1 1 the predicted landslide area ap is between 1265 and 1290 km2 with an average of 1280 km2 which is 75 times the actual landslide area the functional relationship between the ratio of predicted area to real area rpa and the ratio of non sliding samples to sliding samples rns is r pa 99 156 r ns 0 826 it implies that the non slide slide sample ratio determined by the ratio of stable area to the landslide area permits us to construct real probability models to predict the areal percentages of landslides and based on such models the predicted probability is largely consistent with the actual areal percentage of coseismic landslides

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

basal crevasses on the larsen c ice shelf antarctica implications for meltwater ponding and hydrofracture a key mechanism for the rapid collapse of both the larsen a and b ice shelves was meltwater driven crevasse propagation basal crevasses large scale structural features within ice shelves may have contributed to this mechanism in three important ways i the shelf surface deforms due to modified buoyancy and gravitational forces above the basal crevasse creating 10 m deep compressional surface depressions where meltwater can collect ii bending stresses from the modified shape drive surface crevassing with crevasses reaching 40 m in width on the flanks of the basal crevasse induced trough and iii the ice thickness is substantially reduced thereby minimizing the propagation distance before a full thickness rift is created we examine a basal crevasse 4 5 km in length 230 m in height and the corresponding surface features in the cabinet inlet sector of the larsen c ice shelf using a combination of high resolution 0 5 m satellite imagery kinematic gps and in situ ground penetrating radar we discuss how basal crevasses may have contributed to the breakup of the larsen b ice shelf by directly controlling the location of meltwater ponding and highlight the presence of similar features on the amery and getz ice shelves with high resolution imagery 2012 american geophysical union all rights reserved

natural and human induced landsliding in the garhwal himalaya of northern india after the march 28 1999 garhwal earthquake 338 active landslides including 56 earthquake induced landslides were mapped in a 226 km 2 study area in the garhwal himalaya northern india these landslides mainly comprised shallow failures in regolith and highly weathered bedrock involving avalanches slides and flows the total volume of active 33 landslide debris in the region was estimated to be 1 3 million m including 0 02 million m 2 of the total volume moved during and within a few days of the earthquake the denudation produced by the active landsliding within the study area is equivalent to a maximum landscape lowering of 5 7 mm if active landsliding persists for a duration of between 1 and 10 years then denudation due to landsliding is in the order of 0 6 6 mm a y1 approximately two thirds of the landslides in this region were initiated or accelerated by human activity mostly by the removal of slope toes at road cuts suggesting that human activity is accelerating denudation in this region three ancient catastrophic landslides each involving 1 million m 3 of debris were identified and two were dated to the early middle holocene using cosmogenic radionuclide 10 be and 26 al cosmogenic radionuclide 10 be and 26 al were also used to date strath terraces along the alaknanda river in lower garhwal himalaya to provide an estimate of 4m m a y1 for the rate of regional denudation throughout the holocene natural landsliding therefore contributes 5 50 of the overall denudation in this region and is important as a formative process in shaping the landscape q 2001 elsevier science b v all rights reserved

topographical and geological variation of effective rainfall for debris flow occurrence from a large scale perspective abstract understanding the spatial heterogeneity of the debris flow rainfall threshold is meaningful for regional warning systems however regional topographical and geological impacts have not been well quantified using the hengduan mountains with distinct climatic topographical and geological settings as a typical study area this study focused on the geological and topographical variations of effective rainfall for debris flow occurrence from a large scale perspective results showed that the probability of debris flow occurrence was smallest in the cold arid zone and largest in the humid zone the mean dimensionless effective rainfall the ratio of effective rainfall to mean annual precipitation was about 5 2 for an initial warning and 7 7 for serious warnings the contributions to the differences are regional climate geomorphology and geology in sequence of importance the zone with more complex terrain thicker soil and higher sand content would be more beneficial to debris flow formation multiple regression analysis suggested that the geologically related aspects may have a slightly greater effect than topographical factors on effective rainfall in general this work could be in favor of other similar regional national and even global work for debris flow early warning

landslides triggered by the 8 october 2005 kashmir earthquake abstract the 8 october 2005 kashmir earthquake triggered several thousand landslides these were mainly rock falls and debris falls although translational rock and debris slides also occurred in addition a sturzstrom debris avalanche comprising 80 million m3 buried four villages and blocked streams to create two lakes although landsliding occurred throughout the region covering an area of 7500 km2 the failures were highly concentrated associated with six geomorphic geologic anthropogenic settings including natural failures in 1 highly fractured carbonate rocks comprising the lowest beds in the hanging wall of the likely earthquake fault 2 tertiary siliciclastic rocks along antecedent drainages that traverse the hazara kashmir syntaxis 3 steep 50 slopes comprising precambrian and lower paleozoic rocks 4 very steep 50 lower slopes of fluvially undercut quaternary valley fills and 5 ridges and spur crests the sixth setting was associated with road construction extensive fissuring in many of the valley slopes together with the freshly mobilized landslide debris constitutes a potential hazard in the coming snowmelt and monsoon seasons this study supports the view that earthquake triggered landslides are highly concentrated in specific zones associated with the lithology structure geomorphology topography and human presence

evaluation of existing and new methods of tracking glacier terminus change acknowledgements the authors thank two anonymous reviewers for constructive comments that helped to improve the manuscript this research was financially supported by j m l s phd funding from uk natural environment research council grant no ne i528742 1

a seismologically consistent expression for the total area and volume of earthquake triggered landsliding we present a new seismologically consistent expression for the total area and volume of populations of earthquake triggered landslides this model builds on a set of scaling relationships between key parameters such as landslide spatial density seismic ground acceleration fault length earthquake source depth and seismic moment to assess the model we have assembled and normalized a catalog of landslide inventories for 40 shallow continental earthquakes low landscape steepness causes systematic overprediction of the total area and volume of landslides when this effect is accounted for the model predicts the total landslide volume of 63 of 40 cases to within a factor 2 of the volume estimated from observations r2 0 76 the prediction of total landslide area is also sensitive to the landscape steepness but less so than the total volume and it appears to be sensitive to controls on the landslide size frequency distribution and possibly the shaking duration some outliers are likely associated with exceptionally strong rock mass in the epicentral area while others may be related to seismic source complexities ignored by the model however the close match between prediction and estimate for about two thirds of cases in our database suggests that rock mass strength is similar in many cases and that our simple seismic model is often adequate despite the variety of lithologies and tectonic settings covered this makes our expression suitable for integration into landscape evolution models and application to the anticipation or rapid assessment of secondary hazards associated with earthquakes

landslides triggered by the 1994 northridge california earthquake abstract the 17 january 1994 northridge california earthquake m w 6 7 triggered more than 11 000 landslides over an area of about 10 000 km 2 most of the landslides were concentrated in a 1000 km 2 area that included the santa susana mountains and the mountains north of the santa clara river valley we mapped landslides triggered by the earthquake in the field and from 1 60 000 nominal scale aerial photography provided by the u s air force and taken the morning of the earthquake these mapped landslides were subsequently digitized and plotted in a gis based format most of the triggered landslides were shallow 1 to 5 m thick highly disrupted falls and slides within weakly cemented tertiary to pleistocene clastic sediment average volumes of these types of landslides were less than 1000 m 3 but many had volumes exceeding 100 000 m 3 the larger disrupted slides commonly had runout paths of more than 50 m and a few traveled as far as 200 m from the bases of steep parent slopes deeper 5 m thick rotational slumps and block slides numbered in the tens to perhaps hundreds a few of which exceeded 100 000 m 3 in volume most of these were reactivations of previously existing landslides the largest single landslide triggered by the earthquake was a rotational slump block slide having a volume of 8 10 6 m 3 analysis of the mapped landslide distribution with respect to variations in 1 landslide susceptibility and 2 strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the los angeles area

does calving matter evidence for significant submarine melt abstract during the summer in the northeast pacific ocean the alaska coastal current sweeps water with temperatures in excess of 12 c past the mouths of glacierized fjords and bays the extent to which these warm waters affect the mass balance of alaskan tidewater glaciers is uncertain here we report hydrographic measurements made within icy bay alaska and calculate rates of submarine melt at yahtse glacier a tidewater glacier terminating in icy bay we find strongly stratified water properties consistent with estuarine circulation and evidence that warm gulf of alaska water reaches the head of 40 km long icy bay largely unaltered a 10 20 m layer of cold fresh glacially modified water overlies warm saline water the saline water is observed to reach up to 10 4 c within 1 5 km of the terminus of yahtse glacier by quantifying the heat and salt deficit within the glacially modified water we place bounds on the rate of submarine melt the submarine melt rate is estimated at 9 m d 1 at least half the rate at which ice flows into the terminus region and can plausibly account for all of the submarine terminus mass loss our measurements suggest that summer and fall subaerial calving is a direct response to thermal undercutting of the terminus further demonstrating the critical role of the ocean in modulating tidewater glacier dynamics

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

a shaking table model test on a rock slope anchored with adaptive anchor cables abstract to determine the load transfer mechanism and dynamic response characteristics of an adaptive anchor cable aac equipped with a mechanical energy dissipation device a shaking table model test was conducted on rock slope test models anchored with a system consisting of several aacs that were fabricated based on a landslide mass in xiangjiapo during the test the strain of the aac structure and the dynamic response of the slope model were monitored to determine the anchoring mechanism of the aac system and the dynamic characteristics of the aac system anchored slope model the sliding sleeve energy dissipation device of the aac automatically adjusted its tension or deformation to allow its deformation to be consistent with that of the rock and earth mass thereby buffering the impact at the instant of the start of seismic loading the constant sliding resistance of the aac determined its working conditions under a certain seismic loading condition when the constant sliding resistance was set excessively high the energy dissipation device was ineffective under the seismic loading when the constant sliding resistance was set too small the aac slid at the instant of the start of seismic loading however when the constant sliding resistance and the sliding distance were set to proper values the aac slid gradually in a stepwise motion and its peak strain was significantly lower the test results can be used as a reference for designing cut slopes in regions of high seismicity and in selecting anti seismic engineering measures for these slopes

geological and geomorphological characteristics of landslides triggered by the 2004 mid niigta prefecture earthquake in japan abstract the 2004 mid niigta prefecture earthquake mjma 6 8 triggered more than one thousand landslides in the miocene to quaternary sedimentary rocks in japan the most common landslides were shallow disrupted landslides on steep slopes which has been common in many previous disastrous earthquakes in the world the mid niigta prefecture earthquake also triggered more than one hundred deep landslides providing valuable information on the conditions for their occurrence a field investigation and the interpretation of aerial photographs taken before and after the earthquake suggest that reactivation of existing landslides and undercutting of slopes are the most important factors for deep landslides to be triggered by earthquakes in addition planar sliding surfaces seem to be essential for the generation of catastrophic landslides triggered by this earthquake planar bedding parallel sliding surfaces were formed at the boundary between the overlying permeable sandstone and underlying siltstone or along the bedding planes of alternating beds of sandstone and siltstone sliding surfaces along the slope parallel oxidation front were formed in the area of black mudstone new landslides rockslide avalanches occurred with the sliding surfaces in a several cm thick tuff interbedded in siltstone one rockslide avalanche occurred on a slope where buckling deformation preceded the earthquake gentle valley bottom sediments were mobilized in many locations probably because they were saturated and partial liquefaction had occurred due to the earthquake shaking

landslides triggered by the avaj iran earthquake of june 22 2002 abstract the 2002 avaj iran earthquake mw 6 5 triggered many landslides over an area of about 3600 km 2 in this paper we describe a ground based field study conducted during several days immediately after the earthquake and pre and post earthquake landslide inventory maps that were prepared the landslides due to earthquake include 47 fall and topple zones 9 slides and 3 lateral spreads the largest slide is a rockslide 150 100 m which occurred southeast of the village of changureh the main results of this study are the density of earthquake triggered landslides decreases away from the fault zone in a manner that is asymmetric with respect to direction although several slides and lateral spreads were seen the most common types of triggered landslides are falls and topples the area throughout which landslides occurred and maximum epicentral and fault zone distances of landslides are comparable to similar data from other historical earthquakes landslides mostly occurred in the most susceptible geologic units in which there were many landslides before the earthquake new disrupted slides and falls generally occurred in ancient fall zones but no information about reactivation of coherent slides is available

accelerated ice discharge from the antarctic peninsula following the collapse of larsen b ice shelf acceleration exceeds 27 km 3 per year and ice is thinning at rates of tens of meters per year we attribute this abrupt evolution of the glaciers to the removal of the buttressing ice shelf the magnitude of the glacier changes illustrates the importance of ice shelves on ice sheet mass balance and contribution to sea level change index terms 1827 hydrology glaciology 1863 1863 hydrology snow and ice 1827 3349 meteorology and atmospheric dynamics polar meteorology 6924 radio science interferometry 9310 information related to geographic region antarctica citation rignot e g casassa p gogineni w krabill a rivera and r thomas 2004 accelerated ice discharge from the antarctic peninsula following the collapse of larsen b ice shelf geophys res lett 31 l18401 doi 10 1029 2004gl020697

impacts of the chi chi earthquake on subsequent rainfall induced landslides in central taiwan abstract the influence of the chi chi earthquake on subsequent rainfall induced landslides was evaluated by comparing the occurrence of landslides in the choushui river watershed through eight spot images that covered the period from 1996 to 2001 the chi chi earthquake not only triggered serious coseismic landslides itself but also extensively disturbed surface strata around the epicentral area after surface strata have been highly disturbed heavy rainfalls in 2000 and 2001 have triggered more landslides than the earthquake itself compared with the data obtained from images before the earthquake it is obvious that the density of rainfall induced landslides increased significantly after the earthquake and the places where landslides occurred changed as well although typhoon herb in 1996 brought more precipitation than typhoon toraji in 2001 only 9 77 km 2 landslides were induced by herb while 48 8 km 2 landslides almost five times larger than those caused by herb were triggered by toraji besides landslides induced by herb were mainly distributed in mid slope areas with slopes of 20 30 after the chi chi earthquake the rainfall induced landslides occurred mainly in places with slopes between 40 and 50

can low magnitude earthquakes act as a triggering factor for landslide activity examples from the western carpathian mts poland abstract there are numerous examples of the impact of strong earthquakes on landslide activity there is however very little information about the ability of low magnitude earthquakes m

a method for producing digital probabilistic seismic landslide hazard maps abstract the 1994 northridge california earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability these data sets include 1 a comprehensive inventory of triggered landslides 2 about 200 strong motion records of the mainshock 3 1 24 000 scale geologic mapping of the region 4 extensive data on engineering properties of geologic units and 5 high resolution digital elevation models of the topography all of these data sets have been digitized and rasterized at 10 m grid spacing using arc info gis software on a unix computer combining these data sets in a dynamic model based on newmark s permanent deformation sliding block analysis yields estimates of coseismic landslide displacement in each grid cell from the northridge earthquake the modeled displacements are then compared with the digital inventory of landslides triggered by the northridge earthquake to construct a probability curve relating predicted displacement to probability of failure this probability function can be applied to predict and map the spatial variability in failure probability in any ground shaking conditions of interest we anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure

regional patterns of earthquake triggered landslides and their relation to ground motion 1 we have documented patterns of landsliding associated with large earthquakes on three thrust faults the northridge earthquake in california chi chi earthquake in taiwan and two earthquakes on the ramu markham fault bounding the finisterre mountains of papua new guinea in each case landslide densities are shown to be greatest in the area of strongest ground acceleration and to decay with distance from the epicenter in california and taiwan the density of co seismic landslides is linearly and highly correlated with both the vertical and horizontal components of measured peak ground acceleration based on this observation we derive an expression for the spatial variation of landslide density analogous with regional seismic attenuation laws in its general form this expression applies to our three examples and we determine best fit values for individual cases our findings open a window on the construction of shake maps from geomorphic observations for earthquakes in non instrumented regions

landslide inventories the essential part of seismic landslide hazard analyses abstract a detailed and accurate landslide inventory is an essential part of seismic landslide hazard analysis an ideal inventory would cover the entire area affected by an earthquake and include all of the landslides that are possible to detect down to sizes of 1 5 m in length the landslides must also be located accurately and mapped as polygons depicting their true shapes such mapped landslide distributions can then be used to perform seismic landslide hazard analysis and other quantitative analyses detailed inventory maps of landslide triggered by earthquakes began in the early 1960s with the use of aerial photography in recent years advances in technology have resulted in the accessibility of satellite imagery with sufficiently high resolution to identify and map all but the smallest of landslides triggered by a seismic event with this ability to view any area of the globe we can acquire imagery for any earthquake that triggers significant numbers of landslides however a common problem of incomplete coverage of the full distributions of landslides has emerged along with the advent of high resolution satellite imagery

a seismic landslide susceptibility rating of geologic units based on analysis of characteristics of landslides triggered by the 17 january 1994 northridge california earthquake abstract one of the most significant effects of the 17 january 1994 northridge california earthquake m 6 7 was the triggering of thousands of landslides over a broad area some of these landslides damaged and destroyed homes and other structures blocked roads disrupted pipelines and caused other serious damage analysis of the distribution and characteristics of these landslides is important in understanding what areas may be susceptible to landsliding in future earthquakes we analyzed the frequency distribution and geometries of triggered landslides in the santa susana 7 5 quadrangle an area of intense seismic landslide activity near the earthquake epicenter landslides occurred primarily in young late miocene through pleistocene uncemented or very weakly cemented sediment that has been repeatedly folded faulted and uplifted in the past 1 5 million years the most common types of landslide triggered by the earthquake were highly disrupted shallow falls and slides of rock and debris far less numerous were deeper more coherent slumps and block slides primarily occurring in more cohesive or competent materials the landslides in the santa susana quadrangle were divided into two samples single landslides 1502 and landslide complexes 60 which involved multiple coalescing failures of surficial material we described landslide morphologies by computing simple morphometric parameters area length width aspect ratio slope angle to quantify and rank the relative susceptibility of each geologic unit to seismic landsliding we calculated two indices 1 the susceptibility index which is the ratio given as a percentage of the area covered by landslide sources within a geologic unit to the total outcrop area of that unit and 2 the frequency index given in landslides per square kilometer ls km2 which is the total number of landslides within each geologic unit divided by the outcrop area of that unit susceptibility categories include very high 2 5 landslide area or 30 ls km2 high 1 0 2 5 landslide area or 10 30 ls km2 moderate 0 5 1 0 landslide area or 3 10 ls km2 and low

landslides triggered by the 20 april 2013 lushan earthquake sichuan province china abstract the 20 april 2013 lushan earthquake with a magnitude of m s 7 0 induced widespread landsliding along the southern segment of the longmen shan fault zone this paper presents a preliminary analysis of the characteristics of these co seismic landslides triggered in an area of 13 323 km 2 a total of 3810 individual landslide points were identified through an intensive field investigation and from digital aerial photographs taken after the lushan earthquake to facilitate the more detailed analysis on the areal frequency of co seismic landslides as polygons we selected an area of 732 km 2 around the epicenter that had the highest density of co seismic landslides the sizes of the landslides are in general much smaller than those that were triggered by the 2008 wenchuan earthquake the most common types of landslides in the study area were rock falls and shallow disrupted landslides from steep slopes which typically involved the top few meters of weathered bedrock and colluvium in this study the relation between the landslide distribution and five main factors was analyzed fault proximity epicenter proximity peak ground acceleration pga slope angle and lithology our study results show that the landslide concentration tends to decrease with distance from the seismogenic fault and the highest landslide concentration is located within a distance of 5 km regarding the distance to the epicenter the largest landslide density is found at a distance between 5 and 10 km the landslide concentration also increases with increasing slope angle until a maximum for the slope class 45 55 in addition results show that slopes consisting of deeply weathered and fractured sandstones and mudstones were the most susceptible to co seismic landslides in this study we found that the location of the hanging wall and the footwall of the fault did not seem to have an important effect on the landslide distribution this is in contradiction to what has been reported in other earthquake areas such as the wenchuan area

preliminary analysis of some characteristics of coseismic landslides induced by the hokkaido iburi tobu earthquake september 5 2018 japan abstract at 18 07 on september 5 2018 utc a mw 6 6 earthquake struck the iburi tobu area of hokkaido japan the hokkaido iburi tobu hit earthquake is a reverse slip earthquake with a focal depth of 33 4 km at 42 69 n and 142 07 e according to the detailed landslide interpretations there were approximately 7059 landslides induced by this earthquake concentrated in an area of 466 km2 the landslides induced by the hit earthquake are mostly shallow landslides whose sources are mainly an air fall pumice layer from the tarumai volcano and these landslides exhibit an obvious characteristic of a low affected area large landslide area the landslide area follows an exponential distribution and many landslides are composed of multiple subsource areas there are at least 8778 source areas in the whole landslide area the landslides present high mobility and the landslide deposits not only accumulate on the foot but also flow down along the gullies similar to debris flows despite the gullies being gentle

time independent and time dependent behaviour of high latitude flux bundles at the core mantle boundary 1 using a numerical dynamo model we examine whether quasi stationary high latitude flux bundles which are observed in the geomagnetic field over the last 300 years and possibly over much longer time periods result from thermal core mantle interactions we do so by imposing lateral heat flux variations at the core mantle boundary based upon the dominant pattern of seismic heterogeneity in the lowermost mantle we find that the time averaged field then has a similar arrangement of flux bundles to that observed during the last few hundred years however the field is time dependent and this arrangement of flux bundles is not a feature of the field at all times

shaking intensity thresholds for rock falls and slides evidence from 1987 whittier narrows and superstition hills earthquake strong motion records due to inconsistencies in using descriptive intensity scales to describe earthquake shaking necessary to trigger landslides arias intensity a quantity calculated from seismic strong motion records has been employed as a measure of the seismic energy required to initiate landslides because arias intensity is defined as the sum of all the squared acceleration values from a strong motion record it is a measure of the energy dissipated at a site by shaking it incorporates both amplitude and duration information making it more useful to compare with the failure of slopes than parameters such as peak acceleration arias intensities calculated from the 24 october 1987 superstition hills and the 1 october 1987 whittier narrows earthquakes in southern california allow comparisons with the limits of landslides specifically falls and slides from rock and soil in these two earthquakes these comparisons establish two shaking thresholds for the limits of falls and slides a range of 0 08 to 0 6 m sec is observed for tertiary and younger deposits while the range of 0 01 to 0 07 m sec is observed for mesozoic and older rocks these two ranges of shaking levels are controlled by the relative degree of fracturing and aperture of fracture systems within the two general age groups of rocks and soils in the los angeles area and the imperial valley

susceptibility assessment of earthquake triggered landslides in el salvador using logistic regression abstract this work has evaluated the probability of earthquake triggered landslide occurrence in the whole of el salvador with a geographic information system gis and a logistic regression model slope gradient elevation aspect mean annual precipitation lithology land use and terrain roughness are the predictor variables used to determine the dependent variable of occurrence or non occurrence of landslides within an individual grid cell the results illustrate the importance of terrain roughness and soil type as key factors within the model using only these two variables the analysis returned a significance level of 89 4 the results obtained from the model within the gis were then used to produce a map of relative landslide susceptibility

geostatistical modeling to capture seismic shaking patterns from earthquake induced landslides we investigate earthquake induced landslides using a geostatistical model featuring a latent spatial effect lse the lse represents the spatially structured residuals in the data which remain after adjusting for covariate effects to determine whether the lse captures the residual signal from a given trigger we test the lse in reproducing the pattern of seismic shaking from the distribution of seismically induced landslides without prior knowledge of the earthquake being included in the model we assessed the landslide intensity that is the expected number of landslides per mapping unit for the area in which landslides triggered by the wenchuan and lushan earthquakes overlap we examined this area to test our method on landslide inventories located in near and far fields of the earthquake we generated three models for both earthquakes i seismic parameters only proxy for the trigger ii the lse only and iii both seismic parameters and the lse the three configurations share the same morphometric covariates this allowed us to study the lse pattern and assess whether it approximated the seismic effects our results show that the lse reproduced the shaking patterns for both earthquakes in addition the models including the lse perform better than conventional models featuring seismic parameters only due to computational limitations we carried out a detailed analysis for a relatively small area 2 112 km2 using a data set with higher spatial resolution results were consistent with those of a subsequent analysis for a larger area 14 648 km2 using coarser resolution data

mapping earthflows and earthflow complexes using topographic indicators abstract practical methods of mapping earthflows and earthflow complexes using topographic recognition keys are briefly profiled in this article these methods can be employed to tentatively identify earthflow features that may not be recognized on stereopair aerial photographs because of vegetation mollification of the features with age and or unfavorable sun angle on the images conventional usgs 7 5 min topographic maps 1 24 000 scale with contour intervals of 20 ft 6 1 m are not generally useful in identifying earthflows with much less than 18 to 60 m of vertical relief useful recognition keys for the topographic expression of earthflows are presented these keys include divergent contours along a slope fall line with headward cutting upslope and depositional fans downslope fans tend to widen and deepen downslope earthflows in first and second order watersheds may exhibit more dissection of their toe lobes than those in zero order basins earthflows commonly occur in large coalescing complexes with one event or lobe superceding another this forms a series of superposed lobes with the most recent lobes being easiest to discern while older lobes are increasingly mollified with time the soft cohesive clay and silt debris deposited by earthflows is most easily eroded in the headscarp area and compacted naturally in the depositional lobe this makes the recognition of earthflows increasingly difficult with age earthflow debris is often interpreted to be colluvium when deposited on slopes without appreciable shearing to form slickensided contacts discernment of earthflows using topographic recognition techniques depends on the scale and quality of the topographic maps being evaluated

the international bathymetric chart of the southern ocean ibcso version 1 0 a new bathymetric compilation covering circum antarctic waters the international bathymetric chart of the southern ocean ibcso version 1 0 is a new digital bathymetric model dbm portraying the seafloor of the circum antarctic waters south of 60 degrees s

evaluation of camel comprehensive areal model of earthquake induced landslides abstract a new comprehensive areal model of earthquake induced landslides camel has been developed to assist in planning decisions related to disaster risk reduction camel provides an integrated framework for modeling all types of earthquake induced landslides using fuzzy logic systems and geographic information systems camel is designed to facilitate quantitative and qualitative representation of terrain conditions and knowledge about these conditions on the likely areal concentration of each landslide type camel has been empirically evaluated with respect to disrupted landslides category i using a case study of the 1989 m 6 9 loma prieta ca earthquake in this case camel performs best in comparison to disrupted slides and falls in soil for disrupted rock fall and slides camel s performance was slightly poorer the model predicted a low occurrence of rock avalanches when none in fact occurred a similar comparison with the loma prieta case study was also conducted using a simplified newmark displacement model the area under the curve method of evaluation was used in order to draw comparisons between both models revealing improved performance with camel camel should not however be viewed as a strict alternative to newmark displacement models camel can be used to integrate newmark displacements with other previously incompatible types of knowledge

impact of tensile strength and incident angles on a soil slope under earthquake sv waves abstract the tensile strength and incident angles play important roles in seismically induced slope failures in this paper a new criterion for tension shear coupling is proposed based on several sets of relevant lab data and is verified using the experimental data provided by previous researchers this criterion can perfectly depict the tension region as well as the compression region in the entire stress space moreover the tension shear criterion was converted into an expression that could be directly used in a numerical method and it was verified by a numerical example in addition the sv waves were input using the equivalent nodal force method based on a viscous spring artificial boundary this process was implemented by the abaqus software and two numerical examples were used to verify this method subsequently based on the proposed new criterion and input method the impacts of the strength criterion and incident angles on an analysis of seismically induced slope failures were studied the results indicated that the evaluation of the tension shear region is extremely important in the analysis of the seismically induced slope failures the tensile strength of the seismically induced landslides was overestimated by the calculation of mohr coulomb criterion owing to the ambiguous description of the tensile failure or the tension shear failure the assessment of the slope stability was thus not conservative the incident angles of seismic waves affected the travel path and the directivity of slope seismic responses the sliding displacement of the slope side near the epicenter rose with increasing angles of wave incidence the critical slip surface deepened and the hazard aggravated therefore it is important to introduce both the tensile strength and incident angles when evaluating the stability of slopes subjected to seismic loads

undercutting of marine terminating glaciers in west greenland marine terminating glaciers control most of greenland s ice discharge into the ocean but little is known about the geometry of their frontal regions here we use side looking multibeam echo sounding observations to reveal that their frontal ice cliffs are grounded deeper below sea level than previously measured and their ice faces are neither vertical nor smooth but often undercut by the ocean and rough deep glacier grounding enables contact with subsurface warm salty atlantic waters aw which melts ice at rates of meters per day we detect cavities undercutting the base of the calving faces at the sites of subglacial water sgw discharge predicted by a hydrological model the observed pattern of undercutting is consistent with numerical simulations of ice melt in which buoyant plumes of sgw transport warm aw to the ice faces glacier undercutting likely enhances iceberg calving impacting ice front stability and in turn the glacier mass balance

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

gis based landslide susceptibility mapping for the 2005 kashmir earthquake region abstract the m w 7 6 october 8 2005 kashmir earthquake triggered several thousand landslides throughout the himalaya of northern pakistan and india these were concentrated in six different geomorphic geologic anthropogenic settings a spatial database which included 2252 landslides was developed and analyzed using aster satellite imagery and geographical information system gis technology a multi criterion evaluation was applied to determine the significance of event controlling parameters in triggering the landslides the parameters included lithology faults slope gradient slope aspect elevation land cover rivers and roads the results showed four classes of landslide susceptibility furthermore they indicated that lithology had the strongest influence on landsliding particularly when the rock is highly fractured such as in shale slate clastic sediments and limestone and dolomite moreover the proximity of the landslides to faults rivers and roads was also an important factor in helping to initiate failures in addition landslides occurred particularly in moderate elevations on south facing slopes shrub land grassland and also agricultural land were highly susceptible to failures while forested slopes had few landslides one third of the study area was highly or very highly susceptible to future landsliding and requires immediate mitigation action the rest of the region had a low or moderate susceptibility to landsliding and remains relatively stable this study supports the view that 1 earthquake triggered landslides are concentrated in specific zones associated with event controlling parameters and 2 in the western himalaya deforestation and road construction contributed significantly to landsliding during and shortly after earthquakes

landslide processes and landslide susceptibility analysis from an upland watershed a case study from st andrew jamaica west indies abstract rainfall induced landslides are common geomorphic events on the steeper slopes of upper st andrew and cause severe environmental engineering social and economic repercussions in the area a geotechnical study was initiated to identify a past present and potential landslide types and sites for landslides b to examine the nature of geological geomorphological and geotechnical conditions under which failures can take place and c the potential landslide hazard in the area 886 failures were mapped more than 80 of which were located in soils a total of 1 55 km2 9 80 of the total area had failed approximately 59 failures per km2 were mapped with the highest density within elastic sedimentary units and weathered granodiorite 789 failure were mapped on slopes between 20 45 with no failure on slope less than 10 481 failures were mapped along twelve major roadways 46 6 km of road with approximately 10 failures km of road analysis of eighteen geotechnical units within nine geological formations revealed that the highest susceptibility for failure was within old landslide deposits with granular nonplastic to low plasticity soils and on slopes between 20 and 30 the lowest susceptibility was found within white limestones and recent alluvium and terrace deposits granular nonplastic to low plasticity soils are generally more susceptible than fine soils especially on slopes between 30 and 45 while granular and expansive clay soils demonstrate similar susceptibilities but on slopes between 30 and 45 and 20 and 45 respectively clastic sedimentary rocks are more susceptible that igneous lithologies an increase in slope angle increases the susceptibility to failures but only on slopes up to 45 an increase in the degree of weathering of soils and bedrock and fracturing of bedrock as well as road construction increases the landslide susceptibility in the area

influence of sea ice decline atmospheric warming and glacier width on marine terminating outlet glacier behavior in northwest greenland at seasonal to interannual timescales 1 discharge from marine terminating outlet glaciers represents a key component of the greenland ice sheet mass budget and observations suggest that mass loss from northwest greenland has recently accelerated despite this the factors controlling outlet glacier dynamics within this region have been comparatively poorly studied here we use remotely sensed data to investigate the influence of atmospheric oceanic and glacier specific controls on the frontal position of alison glacier ag northwest greenland and nine surrounding outlet glaciers ag retreated by 9 7 km between 2001 and 2005 following at least 25 years of minimal change results suggest that sea ice and air temperatures influence glacier frontal position at seasonal and interannual timescales however the response of individual outlet glaciers to forcing was strongly modified by factors specific to each glacier specifically variations in fjord width and terminus type overall our results underscore the need to consider these factors in order to interpret recent rapid changes and predict the dynamic response of marine terminating outlet glaciers to atmospheric and oceanic forcing

the link between climate warming and break up of ice shelves in the antarctic peninsula a review of in situ and remote sensing data covering the ice shelves of the antarctic peninsula provides a series of characteristics closely associated with rapid shelf retreat deeply embayed ice fronts calving of myriad small elongate bergs in punctuated events increasing flow speed and the presence of melt ponds on the ice shelf surface in the vicinity of the break ups as climate has warmed in the antarctic peninsula region melt season duration and the extent of ponding have increased most break up events have occurred during longer melt seasons suggesting that meltwater itself not just warming is responsible regions that show melting without pond formation are relatively unchanged melt ponds thus appear to be a robust harbinger of ice shelf retreat we use these observations to guide a model of ice shelf flow and the effects of meltwater crevasses present in a region of surface ponding will likely fill to the brim with water we hypothesize building on weertman 1973 hughes 1983 and van der veen 1998 that crevasse propagation by meltwater is the main mechanism by which ice shelves weaken and retreat a thermodynamic finite element model is used to evaluate ice flow and the strain field and simple extensions of this model are used to investigate crack propagation by meltwater the model results support the hypothesis