complete dynamic modeling calibration for the thurwieser rock avalanche italian central alps abstract few rock avalanches have been witnessed and no exact real time description is available the 2 5 m m 3 punta thurwieser rock avalanche september 2004 italian central alps is a unique event for which many quantitative observations have been gathered this is the first case ever of a natural rock avalanche being recorded on video and for which an almost exact value of the total time duration from initial detachment to final deposition is available the landslide travelled over 2 9 km from its source partially in a glacial environment the initial failure and the time for the complete evacuation of the source area were studied and assessed by a series of photos the mean front velocities along the path have been estimated from the video the final geometry and the characteristics of the deposit have been obtained by gps measurements aerial photos field surveys and laboratory tests a quasi 3d continuum dynamic analysis of the landslide motion has been performed assuming both a voellmy and a frictional rheology in the model dan 3d for the first time the landslide front velocities have been used for back analyses and calibration of the rheological parameters together with the final shape and thickness of the deposit and its developing extension the dynamic flow resistance parameters initially calibrated with dan were adopted and validated in dan 3d showing good consistency they are consistent with the existing database for calibrated landslides of similar type and scale flow velocities on the path segment underlain by glacial deposits up to 55 65 m s 1 are more accurately predicted by adopting a frictional rheology up to 50 55 m s 1 with zero pore pressure and a 26 friction angle than by a voellmy rheology up to 40 45 m s 1 both observations and modelling show that glacial ice plays a substantial role in increasing the rock avalanche mobility

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

dynamics of the 1984 rock avalanche and associated distal debris flow on mount cayley british columbia canada implications for landslide hazard assessment on dissected volcanoes abstract in 1984 a mass of quaternary pyroclastic rock est vol 0 74 106m3 slid from the western flank of mount cayley volcano in southwest british columbia the disintegrating rock mass entrained a further 0 20 106 m3 and formed a rock avalanche that travelled a horizontal distance of 3 46 km from its source over a vertical elevation difference of 1 18 km equivalent to a fahrboschung of 19 from the superelevation of the debris trimline in the mid path it is estimated that velocities reached at least 42 m s in the upper part of its path velocities may have approached 70 m s the rock avalanche was partially transformed into a distal debris flow that travelled a further 2 6 km down turbid creek in a narrow channelised path to the squamish river temporarily blocking it the motion of the rock avalanche including the production of a distal debris flow was successfully simulated using a dynamic analytical model both the results of this analysis and field evidence indicate that the rock avalanche did not come to a halt in the upper part of its path as suggested by cruden and lu 1992 but travelled to its distal limit in one uninterrupted movement this finding has important implications for landslide hazard assessment at mount cayley and similar sites the landslide is typical of those which occur on the steep slopes of dissected volcanoes and is one of seven high velocity rock avalanches that have occurred in the garibaldi volcanic belt of southwest british columbia since 1855

effects of near fault seismic loadings on run out of large scale landslide a case study this study presents the run out analysis of the daguangbao landslides subjected to near fault multi direction earthquake forces using discontinuous deformation analysis dda the daguangbao landslide is the largest landslide induced by the 2008 wenchuan earthquake in order to investigate the effects of near fault seismic force on landslide run out kinematic behavior of sliding mass is simulated by a dynamic discrete numerical analysis method called dda in this simulation based on the shape of failure surface and the feature of slope geology the whole slope is divided into three parts base block upper sliding mass and lower sliding mass then two sliding masses are divided into the smaller discrete deformable blocks based on pre existing discontinuities size effect of the huge landslide is also considered baseline corrected real horizontal and vertical ground motions are taken as volume force acting to the base block the results show that seismic force has a significant influence on the landslide progression sliding distance and shape of post failure results of the horizontal and vertical situation are in good agreement with those obtained from post earthquake field investigation remote sensing image and description from the survivors

simulation of a long runout rock avalanche triggered by the lushan earthquake in the tangjia valley tianquan sichuan china abstract only one long runout rock avalanche was triggered by the 2013 lushan earthquake in the tangjia valley tianquan sichuan china the rock avalanche involved the failure of 530 000 m3 of sandstone from the source area the displaced material travelled a horizontal distance of 1600 m with an elevation descent of 480 m equivalent to a fahrboschung of 16 7 based on a detailed field investigation we introduce basic characteristics of the rock avalanche and find that the rock avalanche resulted in one run up in the chunwojian valley a superelevation in the gangoutou valley and increase in volume due to the entrainment of path materials a numerical model dan3d was used to simulate the post failure behavior of the rock avalanche by means of trial and error a combination of the frictional model and voellmy model is found to provide the best performance in simulating this rock avalanche the simulation results reveal that of the rock avalanche lasted approximately 160 s and an average velocity of 10 m s

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

the earthquake triggered rock avalanche of cui hua qin ling mountains p r of china the benefits of a lake damming prehistoric natural disaster abstract this paper deals with an investigation of cui hua rock avalanche in the qin ling mountains in the dong cha valley an eastern branch of taiyi river some 30 km south of xi an province of shaanxi p r of china the landslide originated on lithotectonic structures along seismic active fault systems its occurrence could be correlated with an earthquake in 780 bc that must have triggered the landslide due to a stabilizing human input the landslide area in front of the dammed tianchi lake became an area of settlement for native people of this area which used this rapidly geomorphologic changing system for their needs over the past 2780 years nowadays the lake is considered to be a reservoir for drinking water agriculture and a hydropower plant even more the deposit of the cui hua rock avalanche has become a touristic place for sightseeing and vacation

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

investigation and dynamic analysis of the long runout catastrophic landslide at the shenzhen landfill on december 20 2015 in guangdong china at 11 40 a m december 20 2015 a catastrophic landslide occurred in shenzhen guangdong southeast china seventy seven people were killed and 33 buildings were buried or damaged which were in the direct path of the landslide at the guangming new district the landslide involved 2 73 million m3 of the municipal solid waste msw and had a horizontal runout distance of 1100 m over a vertical distance of 113 m which was equivalent to a fahrboschung of 6 and covered an area of 0 38 km2 basic post failure characteristics are described in this study dynamic simulation software danw and rheological models were used to simulate the runout behavior of the displaced landslide material in order to provide information for the hazard zonation of similar types of potential msw landslides the simulated results revealed that a combination of the frictional model and voellmy model is able to provide the best performance in simulating this landslide also the results showed that this landslide had a duration of about 50 s with a maximum velocity of 22 4 m s it was expected that these models and parameters could improve the accuracy of future hazard assessments of areas with geological topographical and climatic features similar to the shenzhen hong ao landfill

deformation due to the 17 august 1999 izmit turkey earthquake measured from spot images the geometry of the ruptured areas and the coseismic slip distribution data are key to highlighting the behavior of seismic faults this information is generally retrieved from field investigations and geodetic measurements or synthetic aperture radar sar interferometry here we show that spot images can also be used to accurately map the fault zone and to determine the slip distribution by subpixel correlation of images acquired before and after an earthquake the measured slip includes the contribution of possible distributed shear that might not be clearly expressed in surface ruptures and smoothes out possible along strike variability due to near surface fault complexities we apply the technique to the m s 7 4 1999 izmit earthquake our results reveal a 100 m wide and very linear fault zone that can be traced for 70 km from golcuk to akyazi along which supershear rupture has been inferred the obtained slip distribution compares well with the field measurements and is consistent with ground deformation measured at some distance from the fault zone using sar images very little deformation was accommodated off the main fault plane maximum slip is observed near sapanca lake at a small fault jog that has probably influenced rupture propagation

a model for the analysis of rapid landslide motion across three dimensional terrain a new numerical model for the dynamic analysis of rapid flow slides debris flows and avalanches has been developed the model is an extension of an earlier algorithm and is implemented using a nu

observations from the large rapid yigong rock slide debris avalanche southeast tibet the yigong rock slide debris avalanche yra which occurred on 9 april 2000 received worldwide attention as one of the largest nonseismic landslides in recent years with a volume of 0 3 109

dynamic modelling of entrainment in rapid landslides entrainment of path material is an important feature of many rapid landslides the associated increases in volume and changes in flow character can significantly influence mobility a simple material entrainment algorithm based on the assumption of natural exponential growth with displacement has been incorporated into a new computer model designed to simulate rapid landslide motion across 3d terrain the user controls the growth rate and can also implement a change in rheology at the onset of entrainment a hypothetical example is used to demonstrate the influence of the mass and momentum transfer assumptions a back analysis of the 1999 nomash river landslide is included to show that the simple model is capable of simulating the bulk characteristics of a complex event involving substantial entrainment key words landslides debris flows rock avalanches entrainment erosion dynamic modelling

landslide amplification by liquefaction of runout path material after the 2008 wenchuan m 8 0 earthquake china here we propose that an earthquake can trigger the failure of a landslide mass while simultaneously triggering liquefaction of runout path materials before the arrival of the landslide mass thus greatly increasing the size and mobility of an overriding landslide during the 2008 wenchuan earthquake about 60 000 landslides were triggered directly resulting in about 20 000 casualties while these landslides mainly originated from steep slopes some landslides with high mobility formed in colluvial valley deposits among these the most catastrophic was the xiejiadian landslide in pengzhou city which traveled hundreds of meters before coming to rest through field investigation and laboratory testing we conclude that this landslide primarily formed from colluvial deposits in the valley and secondarily from failure of slopes in granitic rock located uphill much of the granitic slope failure was deposited in the upper part of the travel path near the slide head the remainder was dispersed throughout the main landslide deposit superposition of deposits at the landslide toe indicates that landslide debris derived from colluvial soil was deposited first the deposits at the landslide toe displayed flow characteristics such as fine materials comprising basal layers and large boulders covering the deposit surface we hypothesize that the main part of the landslide resulted from seismogenic liquefaction of valley colluvium rather than from liquefaction potentially caused by undrained loading from the granitic slope failures impacting the colluvium to examine the likelihood that seismogenic liquefaction occurred we took samples from different areas of the landslide deposit and performed undrained cyclic shear tests on them in the laboratory the results showed that the sandy soils that comprise most of the deposit are highly liquefiable under seismic loading therefore we conclude that liquefaction of the colluvium in the valley during the earthquake was the main reason for this rapid 46 m s long runout 1 7 km landslide

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

collision rotation and the initiation of subduction in the evolution of sulawesi indonesia the island of sulawesi indonesia has been shaped and deformed as a result of collision with the sula platform a sliver of continental material from the northern margin of australia new guinea the collision has resulted in rotation of the north volcanic arm of sulawesi and the development of the accretionary wedge of the north sulawesi trench the north sulawesi trench changes laterally from a zone of no active deformation in the eastern part to a wide accretionary wedge in the west early stages of thrusting produce a steep frontal slope 8 16 indicative of relatively high basal shear stress whereas the more advanced western zone of thrusting produces a gentle 2 slope consistent with low basal shear stress reported paleomagnetic data suggest post late eocene counter clockwise rotation of the north arm and the offshore geophysics are explained by a pivot of the north arm with respect to the celebes basin about the eastern end of the arc convergence between the north banda basin and southeast sulawesi is documented by the presence of the tolo thrust its outcrop is strongly arcuate and its accretionary wedge varies in width from a minimum of a few kilometers at each end to a maximum of 30 40 km in the central part the northern end transforms to the leftlateral matano fault with a reported offset of 20 km the southern end of the thrust projects toward the deformed rocks of buton but the structural relations there are not clear the matano fault zone appears to connect westward with the palu fault which forms the western transform of the north sulawesi trench the palu matano fault system acts as a trench trench transform between the north sulawesi trench and the tolo thrust and this system is described by the same rotation pole as that for the sulawesi north arm

the landslide story the catastrophic wenchuan earthquake induced an unprecedented number of geohazards the risk of heightened landslide frequency after a quake with potential secondary effects such as river damming and subsequent floods needs more focused attention

spatial correlation of interseismic coupling and coseismic rupture extent of the 2011 mw 9 0 tohoku oki earthquake 1 imaging the extent to which the rupture areas of great earthquakes coincide with regions of pre seismic interplate coupling is central to understanding patterns of strain accumulation and release through the earthquake cycle both geodetic and seismic estimates of the coseismic rupture extent for the march 11 2011 mw 8 9 9 0 earthquake tohoku oki earthquake may be spatially correlated 0 26 0 05 to 0 82 0 05 with a region estimated to be partially to fully coupled in the interseismic period preceding the earthquake though there is substantial variation in the estimated distribution and magnitude of coseismic slip the 400 km long region estimated to have slipped 4 m corresponds to an area of the subduction zone interface that was coupled at 30 of long term plate convergence rate with peak slip near a region coupled 80 the northern termination of rupture is collocated with a region of relatively low 20 interseismic coupling near the epicenter of the 1994 mw 7 6 sanriku oki earthquake and near a region of potential long term low coupling or ongoing slow slip slip on the subduction interface beneath the coastline 40 50 km depth is best constrained by the land based gps data and least constrained on the shallowest portion of the plate interface due to the 230 km distance between geodetic observations and the japan trench

a physical model for widespread near surface and fault zone damage induced by earthquakes 1 i present a rigorous unifying interpretation of the well documented widespread near surface and fault zone damage induced by earthquakes by simulating three dimensional dynamic rupture propagation on a vertical strike slip fault stresses in the crust are depth dependent and material response is governed by the drucker prager yielding criterion i show that material yielding induced by seismic waves under the low confining pressure causes widespread near surface damage because the confining pressure increases with depth the yielding zone at depth is narrowly confined near the fault but its thickness broadens dramatically near the surface forming a flower like damage zone the fault zone damage at depth is induced by large dynamic stresses associated with the rupture front while is induced by strong seismic waves ahead of the rupture front near the earth s surface these results have important implications for the formation and evolution of fault zones and possibly for the dynamic triggering of earthquakes as well

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

catastrophic debris flows on 13 august 2010 in the qingping area southwestern china the combined effects of a strong earthquake and subsequent rainstorms in the wenchuan area in sw china an abundance of loose co seismic landslide debris was present on the slopes after the wenchuan earthquake which in later years served as source material for rainfall induced debris flows or shallow landslides slopes composed of cambrian sandstones and siltstones intercalated with slates appeared to be most susceptible to co seismic landsliding a total of 20 debris flows are described in this paper all were triggered by heavy rainfall on 13th of august 2010 field reconnaissance and measurements supported by aerial photo interpretation were conducted to identify the locations and morphological characteristics of the debris flow gullies in order to obtain information about surface area and volume of landslides and the debris flows the debris flows in the study area were initiated by two processes a run off erosion on co seismic landslide material and concentrated erosion of landslide debris in steep channels b new landslides that transform into debris flows the volume of debris flow deposits on individual fans varies by many orders of magnitude the smallest deposit has a volume of from 5760 to 3 1 million m3 a comparison of the measured volumes deposited on the fan with the volumes of debris stored in the catchment shows the huge potential for future debris flow activity whilst there is a weakly significant positive correlation between these two volumes no significant statistical correlation could be established between volumes of debris flow deposits and other morphometric parameters of the catchment a catastrophic debris flow catchment the wenjia catchment was selected as an extreme case to show in detail the mechanism of debris flow formation as a result of intensive erosion in loose material which was deposited by a rock avalanche during the 2008 earthquake event analyses of the meteorological conditions that triggered these debris flows show one day antecedent precipitation varying between 67 7 and 137 6 mm with a mean rainfall intensity of about 7 3 to 22 5 mm h a rainfall event with peak intensity of 38 7 mm h triggered the largest debris flow event rainfall data related to five debris flow events in the wenjia torrent was used to establish a primary rainfall intensity duration relationship for the triggering of debris flows which was compared to other rainfall duration thresholds from other parts of the world in the discussion emphasis is laid on the need to unravel the process mechanisms which initiated the debris flows for a better understanding and assessment of meteorological thresholds

3d numerical modeling using smoothed particle hydrodynamics of flow like landslide propagation triggered by the 2008 wenchuan earthquake abstract the extremely strong wenchuan earthquake triggered thousands of landslides in sichuan province china flow like landslides such as the tangjiashan wangjiayan and donghekou landslides were among the most destructive causing many casualties and serious economic damage it is therefore important to identify the flow mechanisms and investigate the specific characteristics of these flow like landslides this paper presents a three dimensional model based on smoothed particle hydrodynamics sph to simulate rapid landslide motion across 3d terrain the navier stokes equations in a cfd framework are used as governing equations and artificial viscosity is incorporated into the pressure terms in the momentum equation to dissipate energy to avoid numerical oscillation and particle penetration thus improving the stability of the numerical results a non newtonian fluid model the bingham model has proven suitable for describing the relationship between the shear strain rate and the shear stress in highly deformed soil materials in the proposed model it is used as the constitutive model to describe the fluidization characteristics of flow like landslides combined with the mohr coulomb yield criterion the model incorporates a no slip boundary condition to consider the effect of a solid boundary on slope movement ghost particles are created and assigned an artificial velocity the viscous force caused by the solid boundary is calculated using the relative velocities between the fluid and the boundary particles open multiprocessing openmp an api for multi platform shared memory parallel programming is used to improve the efficiency of the sph code running to show the validity of the proposed approach a benchmark problem of 3d dam break was simulated the calculated distances of the surge front at different times agree well with the test results numerical modeling of the propagation of the tangjiashan wangjiayan and donghekou landslides was performed by the application of sph models to real flow like landslides the whole flow processes of these flow like landslides across the 3d terrain are represented the landslides change direction split or join in and spread or contract in their flow path in response to the local topography time history curves of the velocity and displacement were obtained to analyze the movement characteristics of the landslide mass the shapes of the deposition zones after slide occurrence were investigated comparisons of the sph simulated geometry and the surveyed landslide configurations for the tangjiashan wangjiayan and donghekou landslides were conducted and show a high degree of similarity this indicates that the proposed 3d sph model can accurately represent the evolution of the final slide shape the prediction of the fluidization characteristics of earthquake induced flow like landslides can notably reduce sudden loss of life as it provides a means for mapping hazardous areas for estimating the hazard intensity and for identification and design of appropriate protective measures

a model for the runout analysis of rapid flow slides debris flows and avalanches runout analyses are used for risk assessment and design of remedial measures against rapid landslides such as debris flows debris avalanches rockslide avalanches large scale liquefaction failure

a sph depth integrated model for popocatepetl 2001 lahar mexico sensitivity analysis and runout simulation abstract lahars are debris flows of volcanic origin which can endanger or even destroy communities located near the flanks of volcanoes lahars are not always triggered by eruptions they can form during heavy rainfall or after hydrothermal alteration and volcanic edifice collapse decision makers need lahar hazard maps to devise hazard prevention measures that will prevent casualties so lahar modelling is an important tool for assessing flow behavior and determining inundation areas the depth integrated numerical model used in this study is derived from the velocity pressure of the biot zienkiewicz model and was discretized using the smoothed particle hydrodynamics sph method to simulate a lahar that occurred at popocatepetl volcano in 2001 in order to investigate the convergence of the model we used a range of different sph mesh resolutions once the optimum mesh resolution was bounded we analyzed the model s sensitivity to the initial lahar volume the density of the geomaterial and the rheological parameter of the bingham fluid the results show that the sph depth integrated model produced a highly accurate simulation of the distribution and velocity of the 2001 lahar the study also shows the effects of sph mesh resolution and the relevant influence of rheological parameters

how well do surface slip measurements track slip at depth in large strike slip earthquakes the importance of fault structural maturity in controlling on fault slip versus off fault surface deformation abstract comparisons of observed surface displacements with geodetically inferred slip at depth in six large m w 7 1 strike slip earthquakes reveal a correlation between the structural maturity of the fault and the ratio of deep slip to surface slip that occurs on localized zones of surface rupture specifically structurally immature faults 25 km of total displacement manifest only 50 60 of total slip on narrow fault surface traces versus 85 95 for structurally mature faults 85 km total slip the same pattern holds when structurally simple parts of a surface rupture are analyzed separately from parts that exhibit obvious structural complexity e g discontinuous or multiple traces or significant dip slip these results imply that geologic measurements of surface slip along structurally immature faults are likely to significantly underestimate the true slip at depth in large earthquakes this observation has implications for a number of important problems including determination of fault slip rates which are based on surface offsets earthquake probability assessments which are based on geologic fault slip rates comparisons of geologic and geodetic rate data in the search for strain transients the structural evolution of fault zones estimation of paleo earthquake magnitudes based on geomorphic offsets analyses of the relative importance of faulting vs distributed deformation in accommodating relative plate motions in continental crust the design and construction of infrastructure built near active faults and possibly for the prediction of strong ground motions which may at least partially depend on the degree of slip localization to the surface

importance of horizontal seafloor motion on tsunami height for the 2011 mw 9 0 tohoku oki earthquake abstract it is now clear that the 2011 tohoku oki earthquake ruptured the subduction interface all the way to the japan trench however there is significant disagreement about just how much slip occurred at the trench with most geodetic studies locating only a small fraction of the maximum slip there whereas broadband seismic studies put the majority of the slip near the trench measurements of seafloor displacement near the trench also imply more slip there than is estimated by the geodetic studies here by means of a joint inversion of displacement measurements and seafloor pressure data we show that it is possible to reconcile geodetic and seismic studies and that a considerable amount of slip indeed occurred at the trench with slip magnitudes reaching 57 74 of the maximum slip the seafloor displacement predicted by our model agrees very well with independent measurements made close to the trench we also find good agreement between our tsunami model and independent measurements of tsunami height in the ocean and on land re running of the inversion without the near field pressure gauge data however leads to underprediction of the flooding on land even when the seafloor geodetic data are still included thus even if the seafloor geodetic measurements had been available in real time they would still not have allowed reliable prediction of near field tsunami inundation close to the trench the dip of the plate interface is shallow which serves to decrease the vertical motion of the sea floor for any given slip however the horizontal motion is conversely larger because the ocean floor slopes steeply near the trench it acted like a giant wedge converting the horizontal motion of the ground into an uplift of the water column and causing the peak initial tsunami wave height to be twice as high as it would have been from vertical displacement alone

on characteristics and dynamic analysis of the niumian valley rock avalanche triggered by the 2008 wenchuan earthquake sichuan china on may 12 2008 a large catastrophic rock avalanche was triggered by the wenchuan earthquake on niumian valley in yingxiu town wenchuan county china the displaced landslide materials traveled about 2 640 m with a descent of about 850 m and buried several houses and caused nearly 20 casualties based on detailed field investigation some basic characteristics of this landslide are introduced field investigation showed that the displaced landslide materials experienced three times of run up and twice of superelevation along the run out path and downslope enlargement due to the entrainment of run out path materials a numerical model dan3d is used to simulate the landsliding process by means of trial and error it can be seen that the voellmy model and values of friction coefficient f 0 19 dimensionless and turbulent coefficient xi 2 000 m s2 can provide the best performance in the prediction of sliding and depositing areas the simulated results show that the duration of the rock avalanche is about 120 s with an average velocity of 22 m s

landslides induced by the 2008 wenchuan earthquake sichuan china the 2008 wenchuan earthquake with a magnitude of mw 7 9 induced numerous slope movements on the hanging walls of fault surface ruptures and on steep inner valleys along the minjiang river landslide moving directions showed preferred orientations normal to the fault ruptures indicating the effect of the directivity of the seismic wave the most common landslides were of carbonate rocks which are easily dissolved and decrease the contact surfaces the largest non volcanic landslide in history was induced in bedded dolomite by the earthquake and was preceded by gravitational deformation with ridge top depressions valley fill materials were mobilized at 36 locations probably by pore water pressure build up

effects of new baffles system under the impact of rock avalanches abstract to reduce the flow energy of rockfall in rmountain area a baffle array is set up in the protection zone the optimized design can enhance the efficiency of hazard source energy dissipation project in the present study the arc shaped baffles were studied as compared with the conventional baffles square baffles and cylindrical baffles based on practical engineering the comparison of three types of baffles was discussed in detail by experimental studies which primarily focused on the blocking ability and effectivity in particular by determining the optimal case using those different types of baffles the effects of the optimization of baffle system column spacing row spacing and ld distance between first baffle row and chute terminal were investigated according to the results the arc shaped baffle is the best case among those three types of baffle i e the deposit area and runout are all shorter than those of any other cases with the same value of sr shape changing cylindrical to arc shaped will up regulate the fragment blockage degree the following avalanches will take place close to the avalanche deposition leading to a huge dissipation of kinetic energy moreover by comparing deposition dimensionless velocity u and velocity reduction ratio vrr arc shaped baffle system showed competitive blocking ability when sc 3 5 and sr 4 5 with the rise in the ld the energy dissipation efficiency can be enhanced through the particle collision and particle friction during the geo disaster movement furthermore it can effectively narrow the deposit area and reduce deposit depth and deposit width the results obtained from this study are useful for facilitating design of baffles against rock avalanches

simulation of the sliding process of donghekou landslide triggered by the wenchuan earthquake using a distinct element method in the village of donghekou in qingchuan county sichuan province china a major landslide was triggered by the wenchuan earthquake in 2008 with more than 10 106 m3 of rock displaced the kinematic behavior of this landslide is simulated using a 2d discrete element model the numerical model used in this work is composed of discs bonded together the initial boundary conditions are applied along the ball wall contacts by using an initial velocity estimated from the strong motion data the constraints are mainly issued from the final geometry of the landslide including its capacity to dam the river the modeling thus indicates that a low friction coefficient about 0 1 is required to account for the actual landslide characteristics the runout behaviors are analyzed and some useful conclusions are drawn

source characteristics of long runout rock avalanches triggered by the 2008 wenchuan earthquake china the may 12 2008 wenchuan china earthquake which measured m w 8 3 according to chinese earthquake administration cea m w 7 9 according to the usgs directly triggered many landslides which caused about 20 000 deaths a quarter of the total rock avalanches were among the most destructive landslides triggered by this seismic event and have killed more people than any other type of landslide in this earthquake the donghekou rock avalanche one example of a catastrophic avalanche triggered by the wenchuan earthquake occurred in qingchuan and buried one primary school and 184 houses resulting in more than 780 deaths and in addition caused the formation of two landslide dams which formed barrier lakes combining aerial images resolution of 0 5 m with field investigations this paper lists some parameters of 66 cases in one table and details source characteristics of six typical cases it has been found that most of the long runout rock avalanches have source areas with high relief and steep inclination causing the debris in the travel courses to accelerate there was also a large amount of saturated holocene age loose deposits formed by a river or gully that existed in the travel courses comparison studies indicate that saturated holocene loose deposits in the travel courses could be the most important factor for the causes of the long runout characteristic of the rock avalanches especially when they traveled over gentle or even flat ground surfaces furthermore the relationships among the relief slope gradient runout and covered area are investigated and a threshold line for predicting the maximum horizontal runout distance under certain change in elevation is presented c 2010 elsevier ltd all rights reserved

mass wasting triggered by the 2008 wenchuan earthquake is greater than orogenic growth shallow earthquakes lead to the uplift of mountain ranges but also trigger landslides that remove mass an analysis of the 2008 wenshuan earthquake suggests that more material was removed from the orogen by widespread landslides than was added by coseismic uplift

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

chronology of marine sediments by the racemization reaction of aspartic acid in planktonic foraminifera abstract racemization reaction rate constants of aspartic acid kasp were obtained and compared in bulk foraminifera and in a dissolution resistant foraminiferal species pulleniatina obliquiloculata obtained from marine sediments through ca 20 000 yrbp in the western equatorial pacific the average kasp values were 0 63 10 5 yr 1 for bulk foraminifera and 0 72 10 5 yr 1 for p obliquiloculata this disparity in kasp values could be attributed to the presence of dissolution vulnerable foraminifera in bulk foraminifera it is believed that the leaching of racemized free amino acid having high d l values when the calcareous test was subjected to dissolution through geological time could have led to a lower value of kasp in bulk foraminifera this study thus demonstrates that it is important to analyze a single species of planktonic foraminifera resistant to dissolution in order to avoid spurious changes in kasp values if this condition were satisfied aspartic acid racemization is shown to be extremely useful not only for determining the geological age of marine sediment but also to assess the quality of the sedimentary core stratigraphy

evidence of supershear during the 2018 magnitude 7 5 palu earthquake from space geodesy a magnitude 7 5 earthquake hit the city of palu in sulawesi indonesia on 28 september 2018 at 10 02 43 coordinated universal time it was followed a few minutes later by a 4 7 m high tsunami palu is situated in a narrow pull apart basin surrounded by high mountains of up to 2 000 m altitude this morphology has been created by a releasing bend in the palu koro fault a rapidly moving left lateral strike slip fault here we present observations derived from optical and radar satellite imagery that constrain the ground surface displacements associated with the earthquake in great detail mapping of the main rupture and associated secondary structures shows that the slip initiated on a structurally complex and previously unknown fault to the north extended southwards over 180 km and passed through two major releasing bends the 30 km section of the rupture south of palu city is extremely linear and slightly offset from the mapped geological fault at the surface this part of the rupture accommodates a large and smooth surface slip of 4 7 m with no shallow slip deficit almost no aftershock seismicity was recorded from this section of the fault as these characteristics are similar to those from known supershear segments we conclude that the palu earthquake probably ruptured this segment at supershear velocities the devastating 2018 magnitude 7 5 earthquake in palu indonesia ruptured at supershear speeds according to evidence from space geodesy

vertical acceleration effect on landsides triggered by the wenchuan earthquake china the 2008 wenchuan earthquake with ms8 0 triggered extensive throwing pattern landslides in the area within or near the seismic faults the resultant landslides from this earthquake brought to the fore the effect of vertical earthquake acceleration on landslide occurrence the pseudostatic analysis and the dynamic response on landslide stability due to the wenchuan earthquake are studied with the chengxi west town catastrophic landslide used as a case study the results show that the epicenter distance is an important factor which affects the vertical acceleration and thus the stability of landslide also the vertical acceleration was found to have a significant impact on the fos of landslide if the earthquake magnitude is quite large within the seismic fault the amplitude effect of vertical acceleration is very dominant with the fos of landslide for vertical acceleration ranging from positive to negative having a variation of 25 the variation of fos of landslide for vertical acceleration ranging from positive to negative are 15 and 5 for landslides near seismic fault and outside seismic fault respectively for landslide with a slope angle 45 the fos of landslide with both horizontal and vertical accelerations is significantly greater than the one without vertical acceleration further the results computed from both the pseudostatic method and dynamic analysis reveal that the fos during the earthquake varied significantly whether vertical acceleration is considered or not the results from this study explain why lots of throwing pattern catastrophic landslides occurred within 10 km of the seismic fault in the wenchuan earthquake

rock avalanches triggered by oblique thrusting during the 12 may 2008 ms 8 0 wenchuan earthquake china the 12 may 2008 wenchuan earthquake ms 8 0 triggered over 56 000 landslides over a broad area including shallow disrupted landslides rock falls deep seated landslides and rock avalanches among these landslides rock avalanches are of great concern because of the large volume of displaced material the long runout distance and the resulting fatalities in this paper some rock avalanches including the woqian the tangjiawan the hongyancun the xiejiadianzi and the shuimogou rock avalanches were selected for detailed study mapping of coseismic surface rupture has been carried out at regional and site scales the minor scarps or stepped topographic features observed at the source areas of the rock avalanches correspond spatially to the surface rupture indicating that they should be created by thrusting of a fault that ruptured during the 2008 wenchuan earthquake avalanche deposits of some rock avalanches are shifted northeastward the same direction with the strike slip of the fault rupture compared with the sources of the rock avalanches indicating that the component of strike slip of the fault rupture exerted a horizontal initial velocity on the failed mass for the woqian rock avalanche the source rock on the hanging wall was pushed northeastward creating a hummocky topographic feature because of the right lateral slip of the fault rupture these rock avalanches are therefore triggered by oblique thrust faulting in addition the source rock mass was of poor quality resulting from the shearing and brecciation associated with fault movement in history rendering the rock slopes prone to failure and contributing to the high degree of disintegration of the failed rock mass

diagrammatize movement disintegration patterns of bedding rockslide disintegration in a bedding rockslide often results in damage to structures and lands on the slide mass three disintegration patterns have been proposed through the analysis of bedding rockslide causes in the three gorges area of china using a tree diagram seven affecting factors have been identified and classified by literature analysis and field surveying of 21 bedding rockslides both rough set and synthetic index methods have been employed to analyze the susceptibility of the seven factors and to determine disintegration patterns three main disintegration patterns are indicated for bedding rockslides whole translation and minor disintegration of the slide mass type 1 rapid translation and partial disintegration of the slide mass type 2 and rapid translation and complete disintegration of the slide mass type 3 the slip surface shape a2 the ratio of mass thickness to acceleration distance a4 the profile terrain a5 and the triggering factor a7 are susceptive factors affecting disintegration a matrix graph depicts the criterion that either of the two sets of a2 a5 a7 or a2 a4 a7 can determine the disintegration pattern of a bedding rockslide thereby guiding land use decisions on a bedding rockslide