causes of unusual distribution of coseismic landslides triggered by the mw 6 1 2014 ludian yunnan china earthquake abstract the mw 6 1 2014 ludian yunnan china earthquake triggered numerous coseismic landslides that do not appear to be associated with any previously known seismogenic fault traditional models of triggering for seismically generated landslides do not provide a reasonable explanation for the landslide pattern observed here here the newmark method is applied to a grid to calculate the minimum accelerations required for slope failures throughout the affected region the results demonstrate that for much of the study area the distribution of failure prone slopes is similar to the actual pattern of coseismic landslides however there are some areas where the model predicts considerably fewer failures than occurred we suggest that this is a result of the complex source faults that generated the ludian earthquake which produced a half conjugate rupture on nearly ew and nnw trending faults at depth the rupture directed much of its seismic moment southeast of the epicenter increasing ground shaking and the number of resulting landslides

a scenario study of seismically induced landsliding in seattle using broadband synthetic seismograms abstract we demonstrate the value of utilizing broadband synthetic seismograms to assess regional seismically induced landslide hazard focusing on a case study of an m w 7 0 seattle fault earthquake in seattle washington we computed broadband synthetic seismograms that account for rupture directivity and 3d basin amplification we then adjusted the computed motions on a fine grid for 1d amplifications based on the site response of typical geologic profiles in seattle and used these time series ground motions to trigger shallow landsliding using the newmark method the inclusion of these effects was critical in determining the extent of landsliding triggered we found that for inertially triggered slope failures modeled by the newmark method the ground motions used to simulate landsliding must have broadband frequency content in order to capture the full slope displacement we applied commonly used simpler methods based on ground motion prediction equations for the same scenario and found that they predicted far fewer landslides if only the mean values were used but far more at the maximum range of the uncertainties highlighting the danger of using just the mean values for such methods our results indicate that landsliding triggered by a large seattle fault earthquake will be extensive and potentially devastating causing direct losses and impeding recovery the high impact of landsliding predicted by this simulation shows that this secondary effect of earthquakes should be studied with as much vigor as other earthquake effects online material high resolution maps of relative seismically induced landslide hazard for an m w 7 0 seattle fault earthquake for dry and saturated soil conditions

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

rock avalanches caused by earthquakes source characteristics study of a worldwide sample of historical earthquakes showed that slopes most susceptible to catastrophic rock avalanches were higher than 150 meters and steeper than 25 degrees the slopes were undercut by fluvial or glacial erosion were composed of intensely fractured rock and exhibited at least one other indicator of low strength or potential instability

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

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

controls of earthquake faulting style on near field landslide triggering the role of coseismic slip 1 we compare the spatial distributions of seven databases of landslides triggered by mw 5 6 7 9 earthquakes using distances normalized by the earthquake fault length we show that the normalized landslide distance distributions collapse i e the normalized distance distributions overlap whatever the size of the earthquake separately for the events associated with dip slip buried faulting earthquakes and surface faulting earthquakes the dip slip earthquakes triggered landslides at larger normalized distances than the oblique slip event of loma prieta we further identify that the surface faulting earthquakes of wenchuan chi chi and kashmir triggered landslides at normalized distances smaller than the ones expected from their mw 7 6 magnitudes these results support a control of the seismic slip through amplitude rake and surface versus buried slip on the distances at which landslides are triggered in terms of coseismic landslide management in mountainous areas our results allow us to propose distances at which 95 and 75 of landslides will be triggered as a function of the earthquake focal mechanism

mechanics of the earthquake induced hongshiyan landslide in the 2014 mw 6 2 ludian earthquake yunnan china abstract the hongshiyan landslide the largest landslide volume 12 24 mm3 triggered by 2014 mw 6 2 ludian earthquake blocked the niulan river forming a rockslide dam the failure potential of the dam created an elevated risk to population and infrastructure downstream we provide insight into the failure mechanics of the hongshiyan landslide using data obtained by means of remote sensing techniques and traditional in situ surveys geological data obtained by these methods was then used for kinematic and numerical analyses our study shows that failure of the hongshiyan landslide involved a high rock slope with an average slope of 55 and aspect of 185 ssw in which the geological setting consists of an upper strong limestone slab and an underlying weak silty mudstone the geological setting allowed the landslide to develop as follows i the silty mudstone due to its poor mechanical properties was subject to ductile deformation under the compressive loading from the overlying strong limestone slabs ii a large number of release fractures in the limestone developed as a consequence of pre failure progressive deformation in the underlying weak mudstone iii the oxidation and solution along steep joint walls in the upper limestone indicates that the joints are pathways that allow water ingress into the mudstone further promoting the degradation of shear strength in this layer distinct element modelling udec was used to back analyse the failure mechanism and develop the geological model that best reproduced the hongshiyan failure geometry results show that the failure surface consisted of two elements the upper steeply dipping release surface formed along the slope parallel steep cross joints defining a jointed strong limestone slab and the toe of the failure formed a curved failure surface through the ductile weak silty mudstone underlying the limestone slab independent of any discontinuities within it the pre failure observations and numerical analysis suggest that the hongshiyan slope was in a state of marginal static stability prior to the earthquake as a result of pre failure progressive deformation controlled by the shear strength of the underlying mudstone overall the marginal pre earthquake stability of the hongshiyan slope coupled with the strongest seismic loading which the hongshiyan slope has been historically subjected to are the reasons why this moderate earthquake induced a large scale catastrophic rock slope failure

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

rockfalls triggered by the ad 1356 basle earthquake in the basle region of switzerland we demonstrate that rockfall blocks can be dated accurately using the radiocarbon method soil beneath rockfall blocks containing organic macro remains was sampled at four cliff sites in the tabular jura south east of basle a lightweight drilling rig drills a 101 mm diameter hole through rockfall blocks up to 6 m in height a downhole sampler is used to recover soil samples from below the blocks eighteen radiocarbon dates on charcoal wood needles of conifers and organic macro remains from 11 blocks gave dates between 970 and 440 bp calibrated ages range between ad 1210 and ad 1450 these results along with field observations and historical research suggest that a large number of blocks toppled as rockfalls within a short time interval in the epicentral area of the ad 1356 basle earthquake

the 1989 loma prieta earthquake imaged from inversion of geodetic data we invert geodetic measurements of coseismic deformation from the 1989 ms7 1 loma prieta earthquake to determine the geometry of the fault and the distribution of slip on the fault plane the data include electronic distance measurements global positioning system and very long baseline interferometry vectors and elevation changes derived from spirit leveling the fault is modeled as a rectangular dislocation surface in a homogeneous elastic half space first we assume that the slip on the fault is uniform and estimate the position orientation and size of the fault plane using a nonlinear quasi newton algorithm the best fitting dislocation strikes n48 4 w and dips 76 9 sw consistent with the trend of the aftershock zone and moment tensor solutions bootstrap resampling of the data is used to graphically illustrate the uncertainty in the location of the rupture plane the 95 confidence envelope overlaps the aftershock zone arguing that there is not a significant discrepancy between the geodetic data and the aftershock locations second we estimate the slip distribution using the best fitting uniform slip fault orientation but increase the fault length to 40 km and the downdip width to 18 km the fault is divided into 162 subfaults 18 along strike and 9 along dip each subfault is allowed to have constant right lateral and reverse components of slip we then solve for the slip on each subfault that minimizes a linear combination of the norm of the weighted data residual and the roughness of the slip distribution the smoothing parameter which determines the relative weight put on fitting the data versus smoothing the slip distribution is chosen by cross validation simulations indicate that cross validation estimates of the smoothing parameter are nearly optimal the preferred slip distribution is very heterogeneous with maximum strike slip and dip slip of about 5 and 8 m respectively located roughly 10 km north of the hypocenter there is insignificant dip slip in the southeastern most part of the fault causing the rake to vary from nearly pure right lateral in the southeast to oblique right reverse in the northwest the change in rake is consistent with a uniform stress field if the fault dip increases by about 10 toward the southeast as indicated by the aftershock locations there was little slip above 4 km depth consistent with the observation that there was little if any surface rupture

the 28 october 1996 landslide and analysis of the stability of the current huashiban slope at the liangjiaren hydropower station southwest china on 28 october 1996 a landslide occurred on the huashiban slope near the liangjiaren hydropower station the landslide was caused by a failure mechanism induced by an earthquake mw 7 0 at lijiang on 3 february 1996 after which a tensile fracture zone formed on the huashiban slope the subsequent impact of several small earthquakes on the slope increased the tension crack connectivity and the tensile strength gradually decreased severe rainfall in the rainy season between may and october especially in july and august decreased the shear strength of the bottom sliding surface resulting in a landslide on the huashiban slope on 28 october 1996 the stability of the huashiban slope is important for plant site selection if a further landslide occurs on the slope the liangjiaren hydropower station project will be critically affected so analysis of the current slope stability is extremely important at present the huashiban slope can be divided into five subzones 1 a landslide deposit zone 2 a landslide zone 3 a tensile fracture zone 4 a crescent shaped zone and 5 an upper slide zone using historic landslide data for 28 october 1996 retrospective analysis of the landslide process revealed shear strength parameters for the huashiban slope the cohesion strength is 0 024 mpa the friction angle at the bottom sliding surface is 14 and the tension crack connectivity is 50 these parameters were used to compute the stability of the huashiban slope under the same conditions the stability of the whole slope is better than that of part of the slope and the overall stability is dominated by the tensile fracture zone under earthquake and rainfall conditions it is possible that failure will occur in the tensile fracture zone thus the huashiban slope should be reinforced for construction and operation of the liangjiaren hydropower station

representation of the carbon cycle in box models and gcms 2 organic pump 1 box models of the ocean atmosphere co 2 system rely on mechanisms at polar outcrops to alter the strength of the ocean s organic carbon pump gcm based carbon system models are reportedly less sensitive to the same processes here we separate the carbon pumps in a three box model and the gcm based princeton ocean biogeochemistry model to show how the organic pumps operate in the two kinds of models the organic pumps are found to be quite different in two respects deep water in the three box model is relatively well equilibrated with respect to the pco 2 of the atmosphere while deep water in the gcm tends to be poorly equilibrated this makes the organic pump inherently stronger in the gcm than in the three box model the second difference has to do with the role of polar nutrient utilization the organic pump in the gcm is shown to have natural upper and lower limits that are set by the initial po 4 concentrations in the deep water formed in the north atlantic and southern ocean the strength of the organic pump can swing between these limits in response to changes in deep water formation that alter the mix of northern and southern deep water thus unlike the situation in the three box model the organic pump in the gcm can become weaker or stronger without changes in polar nutrient utilization

earthquake induced landslides and their effects on alluvial fans abstract earthquakes as small as magnitude 4 0 may dislodge landslides from susceptible slopes and larger earthquakes can generate tens of thousands of landslides throughout areas of hundreds of thousands of square kilometers producing billions of cubic meters of loose surficial sediment these landslides can have significant geomorphic effects that vary depending on the landslide characteristics and materials and on the settings in which the landslides occur a review of data from historical earthquakes indicates that the landslides they generated can be classified into 14 different types these include highly disaggregated and fast moving falls disrupted slides and avalanches more coherent and slower moving slumps block slides and earth slides and lateral spreads and flows that involve partly to completely liquefied material rock falls disrupted rock slides and disrupted slides of earth and debris are the most abundant types of earthquake induced landslides whereas earth flows debris flows and avalanches of rock earth or debris typically transport material the farthest because of their abundance or long distances of transport these landslides generally have the greatest effects on the landscape during and after earthquakes landslide effects on alluvial fans include direct deposition of material on fan surfaces fissuring and displacement of fan materials alterations in drainage basins such as devegetation denudation and changes in channel networks and generation of large amounts of sediment that may be transported to fans by post earthquake water flows or debris flows

the paradox of the loma prieta earthquake why did rupture terminate at depth the 1989 loma prieta earthquake was an oblique thrusting event that raptured a moderately dipping fault that is subparallel to the san andreas fault rupture initiated at 18 km and propagated both updip and bilaterally seismic and geodetic studies indicate that rupture terminated between 8 and 5 km depth we examine the role of the elastic properties of the crust as a mechanism for reducing stress in the upper crust and terminating rupture we use linear elastic fracture mechanics and the finite element method to model the loma prieta fault rupture as a mode ii and mode iii shear crack in a layered elastic crust our analysis shows that a low stress condition generated in our models by a change in material properties in the upper crust is capable of stopping rapture we also examine the stress condition at the intersection of the san andreas and loma prieta faults to determine the present state of stress and seismic hazard in the region we find that the loma prieta fault in the upper crust is still closer to the point of failure than the san andreas fault over the same depth rupture of the loma prieta fault did not increase the seismic hazard of the san andreas fault within the crustal volume above the loma prieta rupture

tree ring based reconstruction of rockfalls at cofre de perote volcano mexico in this study dendrogeomorphic techniques are employed to analyse the temporal frequency and spatial distribution of rockfalls on a talus slope of la teta valley located on the nw slopes of cofre de perote volcano at 4000 m above sea level based on the interpretation of disturbance signals in growth rings of old growth pinus hartwegii lindl trees we identify 100 growth disturbances related with rockfall events dated between 1780 and 2011 with slightly more than half of these events being dated to the last 50 years the sectors most susceptible to rockfall correspond with the young rock lobes located at the foot of scarps roughly three in ten events has been triggered by regional m 6 earthquakes whereas half of the events activity coincides with periods characterized by severe prolonged summer rainfalls such as the ones occurred in 1995 1998 2005 and 2011

lake sediments record high intensity shaking that provides insight into the location and rupture length of large earthquakes on the alpine fault new zealand abstract understanding the seismic hazard posed by large earthquakes requires paleoseismic investigation because most faults have not ruptured repeatedly during the period of historic records however determining the location and length of fault ruptures using paleoseismic data remains challenging our study demonstrates that lake sediments record the high intensity shaking that occurs proximal to fault rupture allowing the location and length of ruptures to be reconstructed in two lakes adjacent to the alpine fault new zealand seismic shaking is recorded as subaqueous mass wasting derived turbidites formed by coseismic subaqueous slope failures which are overlain by sets of hyperpycnites representing elevated fluvial sediment fluxes from earthquake induced landslides precise radiocarbon age models show that shaking events are synchronous between the two lake sites and correlate with the timing of known alpine fault earthquakes modelled shaking intensities for the last two alpine fault earthquakes show that subaqueous mass wasting occurs when shaking intensities exceed modified mercalli scale mm vi vii and that fluvial sediment fluxes from earthquake induced landslides occur when shaking intensities exceed mm ix the data demonstrate that lake records distinguish between strong mm vi and violent mm ix shaking at a lake site the ability to map the spatial extent of mm ix shaking provides new insights into the timing and extent of rupture for the last five earthquakes on the alpine fault the study demonstrates that lake deposits constrain the spatial extent of rupture during large earthquakes and may yield long records of the spatial and temporal patterns of fault rupture

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

database and spatial distribution of landslides triggered by the lushan china mw 6 6 earthquake of 20 april 2013 abstract on 20 april 2013 an earthquake with mw 6 6 ms 7 0 hit lushan county sichuan province of china 30 3 n 103 e only 85 km southwest of the 2008 wenchuan mw 7 9 event the lushan shock triggered a large number of landslides with various types including highly disrupted shallow slides and rock falls deep seated landslides and large scale rock avalanches post earthquake high resolution aerial photographs and satellite images as well as a series of pre earthquake high resolution satellite images were collected to construct a detailed accurate objective and complete coseismic landslide database inventory which was validated by field investigation in selected areas based on the aerial photographs 0 2 or 0 6 m resolution that partly cover the affected area and pre earthquake satellite images 14 580 coseismic landslides were recognized and mapped in those areas without post earthquake aerial photographs coverage we mapped 7 948 more coseismic landslides based on post earthquake satellite images rapideye images with 5 m resolution and zy 3 images including panchromatic images with 2 1 m resolution and multi spectral images with 5 8 m resolution and pre earthquake satellite images the 22 528 coseismic landslides with a horizontal projection area of 18 88 km 2 and an estimated total volume of 41 56 10 6 m 3 were distributed in a nearly elliptic area of about 5 400 km 2 correlations between coseismic landslide abundances and topographic geologic and seismic factors were analyzed on 15 546 landslides of area 100 m 2 scatter plots between regional slope angle and landslide abundances in generalized homogeneous lithology combinations show no obvious relationship is present between them which challenges the conclusions of previous studies combining the lushan earthquake triggered landslides with other events on reverse and or thrust faults such as the 1999 chi chi and 2008 wenchuan shocks we found that coseismic landslides tend to occur in areas enveloped by two or more imbricated reverse and or thrust faults rather than only along the seismogenic fault the lushan event shows a higher ability of triggering landslides compared with other earthquakes of similar magnitudes which is likely due to the steep and rugged topography and fractured and densely jointed lithology resulted from long term tectonic activity the blind reverse seismogenic fault is likely also another significant factor based on detailed coseismic landslide inventory maps and databases of several recent major earthquakes such as the 2008 wenchuan 2010 haiti 2010 yushu and 2013 lushan temblors we suggest that the empirical correlations between earthquake magnitude and coseismic landslides need to be updated

the characteristics of the landslides triggered by the wenchuan ms 8 0 earthquake from anxian to beichuan abstract this paper presents a quantitative analysis of the number and area of the landslides triggered by the wenchuan ms 8 0 earthquake from anxian to beichuan in this study the controlling factors of landslides are obtained from geological maps relief amplitude slope and topographic roughness calculated from dem data in arcgis 9 2 a total of 4134 landslides are identified from digital aero image of 1 m resolution covering 19 7 km2 that accounts for 6 4 of the study area the number of landslides with areas less than 5000 m2 is up to 85 22 the smallest landslide is 6 m2 and the largest 1515 000 m2 the number of landslides which have occurred is 1 6 times more prevalent at hanging walls as opposed to foot walls also the relationship between the numbers of landslides and the distances to an earthquake rupture at a hanging wall is linear but exponential at a footwall these results prove that landslide activity is more severe at hanging walls than at foot walls the outcrop area of geologic unit is proportional to the number of landslides except the jurassic triassic and quaternary units r2 0 952 in the study area and landslide density is 19 meanwhile the area of a landslide is linearly proportional to outcrop area of geologic unit except jurassic lower cambrian and quaternary unit r2 0 8279 in the study area and appear to indicate that the lithology does not play an important role in landslides in the study area earthquake triggered landslides tend to be concentrated in specific zones associated with the event controlling parameters such as reliefs slopes and topographic roughness the landslides occurred particularly in the range of 600 1293 m relief amplitudes and the number in this range amounts to 90 of total slides in the studied region moreover landslides easily occurred in the curvature 1 15 with slope between 5 and 55 in addition landslides also usually occurred in the range of 1 1 5 topographic roughness therefore these correlations provide a way to assess regional landslide hazards and are of great significance to regional geohazard planning and prediction

the geotechnical effects of long human habitation 2000 years earthquake induced landslide hazard in the city of zefat northern israel abstract this work studies the effects of long human habitation on site geotechnical conditions it is focused on the city of zefat that is located on the borders of the dead sea transform in northern israel the city of zefat suffered severe damage and loss of life in historical earthquakes as a consequence of earthquake induced landslides eils in this work we evaluate the current eils hazard for the city of zefat using a gis based regional newmark analysis with calibration of the calculated newmark displacement representing eils hazard using maps of field evidence and historical documents testifying to slope instability that occurred in historical earthquakes we found that the core city of zefat is built on a layered anthropogenic material few meters deep which was deposited as a result of more than 2000 years of human habitation the anthropogenic material is mechanically weak susceptible to slope failure and to amplification of seismic shaking it is responsible for the city s devastation in historical earthquakes and it is the source for the current high seismic hazard as well our model shows that earthquakes of magnitudes mw 5 6 and 7 at distances of up to 10 km 50 km and more than 100 km respectively are likely to induce landslides in the core city of zefat the current engineering status of the city is poor and as a consequence severe damage and loss of life are expected in future earthquakes due to eils unless major engineering efforts are made cities in the eastern mediterranean with comparable long habitation histories e g jerusalem tiberias nablus amman are expected to have similar geotechnical problems in their old sections and are advised to take appropriate engineering steps to reduce damage and loss of life in future earthquakes evaluation of historical earthquake magnitudes based on reported local damage may however lead to overestimated magnitudes where the damaged sites are built on anthropogenic talus a common setting in the vicinity of the dead sea transform

horizontal deformation associated with the loma prieta earthquake abstract co seismic horizontal displacements for the 1989 loma prieta earthquake were derived from preseismic triangulation trilateration observations and post seismic gps observations as part of this process the empirical model entitled tdp h91 was applied to correct the preseismic measurements for the crustal motion that occurred during the seven decades spanned by these data these newly derived displacements were combined with previously documented geodetic results to generate a dislocation model for the earthquake our preferred model consists of a vertically segmented rupture surface represented by two rectangles that share a common edge at a depth of 9 km the upper rectangle dips 90 and the lower rectangle dips 70 sw via a trial and error technique the following estimates were found for the remaining parameters strike 134 4 0 7 fault length 32 4 0 7 km upper depth 4 8 0 1 km lower depth 15 1 0 3 km right lateral strike slip 1 86 0 06 m for the upper rectangle and 1 96 0 13 m for the lower rectangle and thrusting dip slip 1 06 0 06 m for the upper rectangle and 2 30 0 18 m for the lower rectangle

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

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

effects of active fault types on earthquake induced deep seated landslides a study of historical cases in japan abstract we investigated the relationship between the distribution of deep seated landslides dsls landslide volume 10 5 m 3 induced by inland earthquakes as well as the distribution of corresponding active faults by compiling preexisting documents on historical dsl occurrence records the following points are found 1 the dsls induced by reverse fault earthquakes tend to occur equally within a wide range of about 20 km from the faults whilst 80 of dsls induced by strike slip fault earthquakes are concentrated within a small range of about 5 km from the faults 2 most of the dsls are distributed on the hanging wall side of the active faults 3 the distribution of some historical dsls may reflect the directivity of the seismic waves of the historical earthquakes the minimum peak ground velocity pgv and peak ground acceleration pga during earthquakes that can induce dsls are estimated to be 15 20 cm s 1 and 300 400 cm s 2 although most of the dsls examined were induced by strike slip fault earthquakes with pgv 60 cm s 1 and pga 900 cm s 2 this discrepancy may be attributed to a possible limitation of the proposed equation which was established mainly for cases of reverse fault earthquakes it is implied that the type of fault the side of the epicenter location hanging wall footwall side and the directivity of seismic waves should be considered for assessing the distribution of ground motion in terms of dsl occurrence and that these factors may reflect the level of risk for earthquake induced landslides around active faults

a late holocene deep seated landslide in the northern french pyrenees abstract a very large deep seated landslide dsl in the northern pyrenees with over 1 4 10 9 m 3 was mapped and dated based on sedimentation rates and 10 be terrestrial cosmogenic radionuclide surface exposure cre dating our analysis on the landslide reveals the role of inherited structures in the landslide process and highlighted typical gravitational morpho structures and a small lake trapped at the toe of the landslide head scarp the rate of lake sedimentation 0 86 0 57 mm yr 1 also provided us with the approximate age of the landslide 1106 540 yr the cre dating result highlights two main slope destabilization phases then we discussed the history of dsl activity and its controlling factors information related to historic markers and the absence of particular climate markers and changes during the medieval dark ages point to a single event in ad 1380 due to a major seismic event lavedan earthquake

determining landslide susceptibility in central taiwan from rainfall and six site factors using the analytical hierarchy process method this work provides a landslide susceptibility assessment model for rainfall induced landslides in central taiwan based on the analytical hierarchy process method the model considers rainfall and six site factors including slope geology vegetation soil moisture road development and historical landslides the rainfall factor consists of 10 day antecedent rainfall and total rainfall during a rainfall event landslide susceptibility values are calculated for both before and after the beginning of a rainfall event the 175 landslide cases with detailed field surveys are used to determine a landslide susceptibility threshold value of 9 0 when a landslide susceptibility assessment value exceeds the threshold value slope failure is likely to occur three zones with different landslide susceptibility levels below slightly above and far above the threshold are identified the 9149 landslides caused by typhoon toraji in central taiwan are utilized to validate the study s result approximately 0 2 0 4 and 15 3 of the typhoon caused landslides are located in the three landslide susceptibility zones respectively three villages with 6 6 0 4 and 4 9 of the landslides respectively are used to validate the accuracy of the landslide susceptibility map and analyze the main causes of landslides the landslide susceptibility assessment model can be used to evaluate susceptibility relative to accumulated rainfall and is useful as an early warning and landslide monitoring tool

seismically induced mass movements and volumetric fluxes resulting from the 2010 mw 7 2 earthquake in the sierra cucapah mexico the observation that sediment flux from mountain ranges struck by high magnitude earthquakes can be strongly influenced by coseismic mass movements brings into question the nature of coseismic deformation as a net contributor to mountain building to better constrain the role of high magnitude earthquakes in orogenesis high resolution data of earthquake induced mass wasting is required for areas of differing tectonic morphological and climatic settings here we compare the erosional flux to the tectonic flux associated with the 2010 mw 7 2 sierra el mayor earthquake in mexico and examine the landslide patterning of coseismic mass movements associated with this event the ruptured fault system has a significant strike slip component with subsidence along the eastern flank and uplift on the western flank of the range peak ground acceleration was highest along the steepest sections of the range such that the frequency of landslide occurrence was strongly correlated to slope gradient both vertical and horizontal coseismic displacement demonstrated a strong control over landslide initiation this result suggests that strike slip systems experience very different landslide patterning to thrust faults during earthquakes based on interferometric analysis of synthetic aperture radar images the earthquake resulted in a total uplifted volume of 41 6 106 m3 and a loss of 95 2 106 m3 due to subsidence this suggests a net tectonic volumetric flux of 53 6 106 m3 sediment mobilisation by coseismic landslides is estimated at 2 7 106 m3 derived from a manually mapped inventory using spot 5 multispectral imagery thus the net volume loss through coseismic subsidence of the mountain range generated a strongly negative mass flux which was only marginally enhanced by mass wasting

distribution and characteristics of loess landslides triggered by the 1920 haiyuan earthquake northwest of china abstract on december 16 1920 an earthquake with a magnitude of 8 5 occurred in haiyuan county ningxia hui autonomous region northwest of china this earthquake triggered several thousand loess landslides which resulted in thousands of deaths and blockages of rivers the distribution and characteristics of the landslides triggered by the haiyuan earthquake in loess areas were studied using satellite images and field investigation a total of about 3700 landslides with a cumulative area of about 177 km2 were interpreted over an area of 21 000 km2 it was found that landslides triggered by the earthquake were concentrated in a western of 40 55 km from the haiyuan fault landslides were concentrated near ridge crests with 65 7 of the landslides originating in the upper quadrant of slopes the aspects of the landslides triggered by the haiyuan earthquake were parallel to the faults and there is no back direction effect in landslides triggered by haiyuan earthquake these landslides have long run out distances travel distance l height different h 0 6 and deposited materials in river channels forming 51 dammed lakes that still exist the relationship between the area a and volume v of the landslides is v 4 170 a1 086 based on the relationship between number and volume of landslide and the magnitude of earthquake 100 000 landslides with a cumulative volume of 0 5 1010 m3 were triggered by the haiyuan earthquake as loess is sensitive to liquefaction during an earthquake and tends to produce landslides with long travel distances hence the loess depth slope and geological stresses are the primary factors responsible for the high density of landslides in this region

multimodal method for coseismic landslide hazard assessment abstract regional scale coseismic landslide hazard assessments have traditionally been based on infinite slope analyses considering only a single mode of failure inventories and landslide reconnaissance work have shown a diverse range of coseismic landslide modes with significantly different consequences of failure this paper presents a multimodal approach for regional scale coseismic landslide hazard assessment through a two step procedure the multimodal method explicitly accounts for four general landslide types commonly observed during earthquakes rock slope failures disrupted soil slides coherent rotational slides and lateral spreads first the susceptibility to each landslide mode is evaluated based on topography second coseismic landslide hazards are assessed using mode specific geotechnical models a trial multimodal landslide assessment is presented for the seismically active country of lebanon results show that the computed coseismic landslide hazard closely matches field verified slope activity across different regions of the country exhibiting a range of failure modes these results qualitatively demonstrate the efficacy of the procedure and suggest that multimodal coseismic landslide hazard analysis is especially well suited for regions with varying terrain and where landslide inventories are not available

geodetic estimate of coseismic slip during the 1989 loma prieta california earthquake offsets in the relative positions of geodetic stations resulting from the loma prieta earthquake can be explained with a dislocation model that includes buried oblique slip on a rupture surface extending 37 km along the strike of the san andreas fault dipping 70 degree to the sw and extending from a depth of about 5 to 17 5 km assuming uniform slip on a rectangular surface the mean values for a range of reasonable fault geometries are 1 6 plus minus 0 3 m right lateral strike slip and 1 2 plus minus 0 3 m reverse slip slip on an adjacent extension of the rupture to the southeast recorded in the aftershock sequence is not well constrained by the geodetic data the geodetic data clearly preclude rupture extending near the surface

faulting geometry and slip from co seismic elevation changes the 18 october 1989 loma prieta california earthquake abstract leveling surveys conducted before and after the loma prieta earthquake provide observations of the co seismic elevation changes these data are used to determine the faulting geometry and distribution of slip considering planar listric and negatively listric fault shapes both the planar and nonplanar models produce elevation changes consistent with the observations most of the observed elevation changes can be modeled with a rupture surface that extends from 4 to 15 km depth if the rupture surface is planar the observations require 2 4 m of right lateral strike slip and 1 7 m of reverse slip on a 34 km long plane that dips 60 sw the best fitting model faults lie above and to the southwest of the aftershock zone a significantly better fit to the observations is obtained when these fault geometries are allowed to have two rake values with a larger thrust component northwest of the epicenter and a larger strike slip component southeast of the epicenter when a low modulus layer over a half space is used for consistency with the seismic p wave velocity structure the fault deepens coming within 3 km of the hypocenter but still locates several kilometers southwest of most aftershocks

site characterization for urban seismic hazards in lower manhattan new york city from microtremor array analysis 1 we characterize the shear wave velocity vs of soil deposits in lower manhattan at six sites using the spac and hvsr microtremor methods the soil vs ranges from 140 m s to 300 m s over bedrock we believe that bedrock depth is constrained to 15 with these microtremor data but an accurate quantification of bedrock vs is unattainable because of low spectral coherency at frequencies below 3 hz hvsr data corroborate the spac microtremor results at sites based on good alignment of theoretical rayleigh ellipticity peaks 1d sh amplifications and peak hvsr resonant frequencies vary between 1 4 and 5 5 hz between the sites from both observed hvsr and predicted 1d sh amplification shear wave velocities to 30 m classify the sites as c d or e this study demonstrates that given relatively shallow bedrock depth the spac method can work in extremely urbanized areas

a statistical model for the impact of the 1999 chi chi earthquake on the subsequent rainfall induced landslides a statistical model is proposed for the temporal impact of the 1999 chi chi earthquake on the subsequent rainfall induced new landslides in the choushui river watershed of central taiwan based on daily precipitation records from 1996 to 2008 and the landslide inventories obtained from satellite images taken in this period the parameters of the model functions were obtained by genetic algorithm the proposed model estimates new landslide density from daily precipitation with an average error of 13 91 to the variation analysis result from landslide inventory over 15 image dates the model estimation reveals a continuously decaying pattern of earthquake impact on the subsequent rainfall induced new landslides an average daily 0 004 background new landslide density and a 4 97 new landslide density caused by the earthquake directly within the study area also the model suggests that there are impacts and latency of antecedent precipitation among the occurrence of new landslides

characteristics and remediation of a landslide complex triggered by the 2008 wenchuan china earthquake case from yingxiu near the earthquake epicenter during the 2008 wenchuan earthquake the river valley from yingxiu to wenchuan experienced numerous landslides and became a prominent area of landslide complexes the present large landslide complex near the earthquake epicenter consisted of laohuzui slide 1 laohuzui slide 2 and douyaping slide the scale geology morphology sliding process and failure mechanism of the landslide complex are analyzed by means of field investigation aerial photograph and stereographic projection technique characteristics of these three slides including seismic response of slope landslide debris damage and potential failure are discussed the convex slope and the upslope of fractured granitic rock at high altitude are highly prone to landsliding under earthquake the high source altitude and long travel path determine grain sizes and the deposit angle of the slide debris the landslide complex completely buries the g213 roadway and dams up the minjiang river in these sections after the earthquake rainfall aftershocks and river erosion may retrigger new failures such as retrogressive slide of weathered fractured rock colluvial landslide debris flow embankment failure and rockfall the following are presented as suggested remedial measures to protect the roadway and stabilize the slope the removing and trenching protective concrete rock blocks against erosion retaining structure rockfall stopping wall rockfall restraining net rock bolt and the planting of vegetation

the mechanism of high speed motion and damming of the tangjiashan landslide abstract understanding the mechanisms of landslide failure and resulting damming processes is crucial for constraining the hazard chain associated with landslide damming events on may 12 2008 the wenchuan earthquake caused a large number of secondary hazardous events such as landslides and collapses most of which occurred in high mountain gorges in these areas the sliding distance of landsides is often very short and the landslides are often characterized by high speed short distance and damming using the tangjiashan landslide damming events induced by the wenchuan earthquake as a model this paper reconstructs the three dimensional failure and associated damming caused by the landslide based on a detailed geological investigation of the landslide area and using the dynamic finite element technique the study proposes a four stage model for the failure and damming process of the tangjiashan landslide earthquake induction and progressive destruction of the slide body destruction and high speed sliding of the slide body slide body impact disintegration and river blockage for the formation of a damming body and vibration compression the average speed of the tangjiashan landslide reached a maximum value of 22 m s about 30 s after the earthquake and the landslide reached stability about 60 s later

forecasting landslide hazard by the 3d discrete element method a case study of the unstable slope in the lushan hot spring district central taiwan abstract catastrophic landslides and related phenomena are commonly facilitated by the subtropical climate with frequent typhoons and recurrent earthquakes in taiwan s mountainous areas one area susceptible to potentially catastrophic landslides is located at lushan in central taiwan which is famous for its hot springs and tourism the northern slope above the hot spring district slips gradually and frequently due to heavy rainfall for safety reasons the slip affected area has been under constant borehole monitoring by government agencies and a controversial public debate has arisen over permanent evacuation of the hot spring district in this study we attempt to simulate possible scenarios of catastrophic slope failure using slip geometries derived from the monitoring data and assess potential landslide impact areas by a discrete element method using the pfc3d code in the worst case scenario the lushan hot spring district is predicted to be destroyed by debris in 20 s besides the planned regional emergency refuge is rapidly jeopardized by flooding resulted from landslide dammed lakes this study addresses catastrophic slope failure under heavy rainfall conditions given a range of friction coefficients and varied continuity of the failure surfaces it is noted that the pfc3d code has limitations in modeling all complex mechanisms of landslide particularly in modeling loss of material shear strength due to increases in pore pressure nevertheless the numerical simulation results by the 3d discrete element method provide scenario based runout paths particle velocities and landslide affected areas which are useful information for decision support and future landslide hazard assessment

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

spatial distribution of landslides triggered from the 2007 niigata chuetsu oki japan earthquake abstract understanding the spatial distribution of earthquake induced landslides from specific earthquakes provides an opportunity to recognize what to expect from future events the july 16 2007 mw 6 6 mjma 6 8 niigata chuetsu oki japan earthquake triggered hundreds of landslides in the area surrounding the coastal city of kashiwazaki and provides one such opportunity to evaluate the impacts of an offshore magnitude 6 earthquake on a steep coastal region as part of a larger effort to document all forms of geotechnical damage from this earthquake we performed landslide inventory mapping throughout the epicentral area and analyzed the resulting data for spatial seismic motion and geologic correlations to describe the pattern of landsliding coupled with examination of a third party aerial photo based landslide inventory our analyses reveal several areas of high landslide concentration that are not readily explained by either traditional epicentral and fault plane distance metrics or by recorded and inferred ground motions whereas average landslide concentrations averaged less than 1 landslide per square kilometer ls km2 some areas reached up to 2 ls km2 in the nishiyama hills to the northeast of kashiwazaki and between 2 and 11 ls km2 in coastal areas to the north and south of the city correlation with seismometer based and monument overturning back calculated ground motions suggests that a minimum peak ground acceleration pga of approximately 0 2 g was necessary for landsliding throughout the region but does not explain the subregional areas of high landslide concentration however analysis of topographic slope and the distribution of generally weak dip slope geologic units does sufficiently explain why on a sub regional scale high landslide concentrations occurred where they did these include 1 an inland region of steep dip slope anticlinal sedimentary strata with associated fold belt compression and uplift of the anticline and 2 coastal areas with generally weaker weathered outcrop lithology and steeper slopes resulting from active marine and terrestrial cliff processes the results offer lessons for understanding the effects of earthquakes on both regional and subregional scales with regard to the spatial distribution of landsliding

fault zone controls on the spatial distribution of slow moving landslides slow moving landslides earthflows can dominate hillslope sediment flux and landscape erosion in hilly terrain with mechanically weak fine grained rock controls on the occurrence of slow moving landslides are poorly constrained and need to be understood for landscape evolution models sediment budgets and infrastructure and hazards planning here we use airborne interferometric synthetic aperture radar insar and aerial photographs to document 150 previously unidentified active earthflows along the central creeping portion of the san andreas fault california the earthflows move seasonally in response to winter rainfall occur on hillslopes at 20 40 gradients less than typically associated with rapid catastrophic landslides and have similar morphological characteristics to earthflows in different climatic and tectonic settings although our data extend up to 10 km from the fault trace 75 of detected landslides occur within 2 km of the active fault topographic precipitation and rock type metrics alone are not enough to explain the observed spatial distribution of earthflows instead we hypothesize that earthflows cluster near the creeping san andreas fault because of a fault induced zone of reduced bulk rock strength that increases hillslope susceptibility to failure in addition similar lithology topography and climate exist north of the creeping section of the fault yet earthflows there are rare this may be due to large magnitude earthquakes episodically triggering coseismic rapid landslides which preferentially remove weak rock from the fault damage zone our analysis suggests that the necessary conditions for earthflow formation in central california include some combination of reduced rock strength fine grained sedimentary rock threshold precipitation and relief and possibly the absence of large magnitude earthquakes these conditions likely hold for earthflow development in other areas and our work suggests that local variations in rock strength and seismicity such as those associated with fault zones need to be taken into account in order to accurately predict earthflow occurrence

comment on spatial distribution analysis of landslides triggered by 2008 5 12 wenchuan earthquake china by shengwen qi qiang xu hengxing lan bing zhang jianyou liu engineering geology 116 2010 95 108

relations between density of earthquake damaged trace and environmental factors in seismic intensity a case study in wenchuan county china many studies have been designed to assess seismic hazard and to improve post earthquake damage evaluation models compared with previous studies the research attempted to solve the problems of the effectiveness differences of seismic intensity on density of earthquake damaged trace de and established the appropriate models for de in different scale of seismic intensity de as a relative value reduced the influence of area on earthquake damaged trace the research will provide the necessary scientific support to fast post earthquake damage assessment and modeling by utilizing gis rs and field investigation data the spatial distribution characteristic of earthquake damaged traces was analyzed effective factors including seismic intensity distance to rivers and slope were identified through pca specifically seismic intensity was identified as the key factor the inherent relations between de and seismic intensity de and distance to rivers in seismic intensity and de and slope in seismic intensity were modeled by regression analysis the results demonstrated that both earthquake energy and de have attenuation characteristics there is a significant positive correlation between de and seismic intensity the pearson correlation is 0 917 that is the higher the seismic intensity the greater the de was the erosion of river leads to steep slope which is in favor of the formation of mountain hazards de showed the decreasing tendency with the increasing distance to river with the increase of slope the de gradually became stronger for distance to river the largest changing rate of de appeared on seismic intensity xi but for slope the largest changing rate of de appeared on seismic intensity x

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

evaluation of anfis and lr models for seismic rockfalls susceptibility mapping a case study of firooz abad kojour iran earthquake 2004 seismic rockfall is one of the prevalent geohazards that cause huge losses in the earthquake stricken areas in the present research a model is developed to map susceptibility occurrence probability of seismic rockfalls in a regional scale using logistic regression lr and adaptive neuro fuzzy inference system anfis techniques in this research firooz abad kojour earthquake of 2004 was introduced as the benchmark and the model base the susceptible zones predicted by lr and anfis methods were compared with the database distribution map of seismic rockfalls by which the results revealed a good overlapping between the susceptible zones predicted by the anfis and the field observation of rockfalls triggered by this earthquake besides for the statistical evaluation of results obtained by lr and anfis models the verification parameters with high accuracy such as density ratio dr quality sum qs and receiver operating characteristic curve roc were used by analyzing the susceptibility maps and considering the qs index obtained by lr 21 04184 and anfis 26 75592 it could be found that the qs of anfis is higher than that of lr moreover based on the obtained value of the area under the curve auc from lr 0 972 and anfis 0 984 methods anfis provided a higher accuracy in zonation and susceptibility mapping of rockfalls triggered by firooz abad kojour earthquake of 2004 compared to the lr method

coseismic landsliding estimates for an alpine fault earthquake and the consequences for erosion of the southern alps new zealand landsliding resulting from large earthquakes in mountainous terrain presents a substantial hazard and plays an important role in the evolution of mountain ranges however estimating the scale and effect of landsliding from an individual earthquake prior to its occurrence is difficult this study presents first order estimates of the scale and effects of coseismic landsliding resulting from a plate boundary earthquake in the south island of new zealand we model an mw 8 0 earthquake on the alpine fault which has produced large m 7 8 8 2 earthquakes every 329 68 years over the last 8 ka with the last earthquake 300 years ago we suggest that such an earthquake could produce 50 000 20 000 landslides at average densities of 2 9 landslides km 2 in the area of most intense landsliding between 50 and 90 are expected to occur in a 7000 km2 zone between the fault and the main divide of the southern alps total landslide volume is estimated to be 0 81 0 87 0 55 km3 in major northern and southern river catchments total landslide volume is equivalent to up to a century of present day aseismic denudation measured from suspended sediment yields this suggests that earthquakes occurring at century timescales are a major driver of erosion in these regions in the central southern alps coseismic denudation is equivalent to less than a decade of aseismic denudation suggesting precipitation and uplift dominate denudation processes nevertheless the estimated scale of coseismic landsliding is considered to be a substantial hazard throughout the entire southern alps and is likely to present a substantial issue for post earthquake response and recovery

using provenance analysis in an anthropocene natural laboratory abstract globally anthropogenic perturbations to sediment dispersal systems produce detrital signals that are evident in the recent sedimentary record we review the study of anthropogenic perturbations to sediment dispersal systems from the perspective of detrital signals and discuss the use of provenance analysis in anthropocene sedimentology anthropocene provenance analysis is illustrated by a case study from the monterey bay sediment dispersal system mbds of coastal and offshore central california u s a the mbds records two phases of alterations to sediment flux an early increase in fine flux recognized in increased sedimentation rates and a later decrease in coarse flux recognized in detrital provenance signatures results from the mbds suggest that a multi methodological approaches employing provenance analysis and detailed short timescale 102 104 yr depositional chronology markers combined with the study of other anthropocene indicators like the introduction of non natural detritus are valuable tools for describing natural sedimentary processes in addition to human alterations to natural systems the recognition and description of such perturbations to sediment supply is increasingly recognized as an important variable in understanding the effects of human driven landscape alteration particularly in the face of a changing climate the broad concepts and approach outlined in this study provide tools that can extend environmental observations past the period of historical record and can be used to understand past and predict future impacts of altered sediment flux in response to drivers like climate change and sea level rise

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

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

the role of seismic triggering in a deep seated mudstone landslide china historical reconstruction and mechanism analysis abstract deep seated mudstone landslides are widely distributed in northwest china the zhengjiamo landslide occurred in 734 ce near taijing tianshui region it was triggered by the main shock of the historical ms 7 0734 ce earthquake the earthquake also induced a wide range of landslides in this area with hundreds of fatalities and many houses destroyed by landslide debris based on a detailed field survey borehole data and mapping a detailed geological reconstruction of the slope was achieved and the geo mechanical features of the claystone involved in the landslide were obtained using the particle flow code to simulate the mechanism of the zhengjiamo landslide the features of the landslide dynamics were obtained using a 5 stage model during the landslide process the slip mass at the front and upper edges exhibited higher mobility than at the rear and bottom edges furthermore the contact bond strength of the sliding body gradually weakened the model indicates that the particle bond strength has a larger influence on the maximum runout distance and landslide debris morphology than the type of weak intercalated layers the slip mass presented a rotational slide pattern and remained on the slip plane throughout the sliding process finally the earthquake uplifted the slope toe which prevented the slip mass from gliding the modelled scenario provided a reasonably good fit to the actual topography verifying the modelling results after the historical earthquake with the clay minerals swelling and shrinking under rainfall and efflorescence conditions the structure of the soft rock changed contributing to the weakening of the sliding rock mass the landslide gradually crept and evolved to its current topography

dynamic distinct element analysis of the 800 m high aknes rock slope dynamic analysis of the 800m high aknes rock slope using udec dynamic distinct element analysis of the 800 m high aknes rock slope

the tsaoling landslide triggered by the chi chi earthquake taiwan insights from a discrete element simulation article i nfo in the village of tsaoling in yunlin county taiwan a major landslide was triggered by the chi chi earthquake in 1999 with more than 125 10 6 m 3 of rock displaced the kinematic behaviour of this landslide is simulated using a 2d discrete element model pfc2d code our numerical model is composed of discs bonded together the initial boundary conditions are applied along the ball wall contacts by using derived velocities integrated from the strong motion data with a duration of 160 s including the peak acceleration near tsaoling the constraints are mainly issued from the final geometry of the landslide including its capacity to cross the river valley and reach a significant elevation on the opposite mountain flank they also result from a variety of geological and hydrological observations including the local levels of material disruption and the location of survivors our modelling thus indicates that a low friction coefficient about 0 15 and a medium strength are required to account for the actual landslide characteristics a self lubrication mechanism probably accounts for the low residual friction our model also suggests that the maximum velocity of sliding reached 50 m s a result that cannot be checked in the absence of actual measurements in addition to friction the strength of sliding block is of special importance because it controlled the possibility for the upper layer fragments to roll and get buried and hence the probability of survival

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

coseismic deformation and dislocation models of the 1989 loma prieta earthquake derived from global positioning system measurements global positioning system gps surveys were used to determine coseismic displacements within the epicentral region of the 1989 loma prieta earthquake near santa cruz the california highway department caltrans conducted the preearthquake survey in february and march 1989 using single frequency gps receivers in march 1990 we reoccupied eight of the caltrans stations using dual frequency receivers relative displacements were computed by differencing the station coordinates determined from these two surveys displacements were determined relative to sites remote from the earthquake by incorporating gps measurements from loma prieta station lp1 to the very long baseline interferometry vlbi site at fort ord examination of repeated measurements in the single frequency preearthquake survey indicates precision is 10 mm in the horizontal although it may be as low as 40 mm in the weakly connected part of the network the precision in the vertical is generally 30 40 mm in contrast the largest observed coseismic displacement is 410 mm horizontal and 341 mm vertical we use a quasi newton method to estimate the parameters of the uniform rectangular dislocation source that best fits the observed displacements the best fitting dislocation dips 68 southwest extending from 3 to 16 km depth strikes n66 w and has 1 8 m of dip slip and 1 2 m of strike slip the best fitting dislocation overlaps the aftershocks but is rotated 15 counterclockwise from the trend of the afterhock zone we find that the data can be fit nearly as well with a dislocation that is constrained to lie in the plane of the aftershocks in this case the fault extends from 5 to 15 km depth the constrained model explains 96 of the data both models have a moment of m0 2 9 1019 n m we also use the quasi newton method to estimate rectangular dislocation models from the leveling data of marshall et al 1991 and the trilateration and gps data of it lisowski et al 1990 in contrast to the previous studies we find that both of these data sets are independently best fit with dislocations embedded within the aftershock zone

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

mass movement in cordon de las osamentas de la flecha river basin san juan argentina abstract the de la flecha river basin is located to the southwest of san juan province at around 31 50 s 68 57 w in this area a total of twenty debris rock slides in the cordon de las osamentas were mapped and studied the mode of failure of each was determined to be a rotational slide the areal extent of the smallest observable landslide body is approximately 0 58 km2 and the largest is 367 76 km2 the slides were detected through high resolution satellite imagery interpretation digital elevation models and field surveys by identifying both the landslide detachment zones and landslide bodies based on the geographic information system gis the slides have varying controlling factors including lithology and slope which seem to be the main controlling factors in causing slope instability the spatial relationships among the landslides and the distribution of seismic epicentres historical earthquakes and quaternary faults maradona las osamentas papagayos faults la chilca and el mocho faults were analysed these gravitational movements were triggered by seismic shocks associated with active faults

spatial distribution analysis of mass movements triggered by the 2005 kashmir earthquake in the northeast himalayas of pakistan abstract distribution of the mass movements triggered by the 2005 kashmir earthquake was analysed in the vicinity of jhelum valley neelum valley and muzaffarabad in the northeast himalayas of pakistan mass movements were mapped using spot satellite imagery and field investigations geographic information systems gis were used to analyse the relations of the distribution of these mass movements using various parameters such as distance from an earthquake source epicentre and fault topographic parameters slope steepness slope aspect and elevation and geological units the results of the analysis indicate that the mass movement concentration decreases with increased distance from the earthquake epicentre and the reactivated muzaffarabad fault the maximum concentration of mass movements is near the epicentre and a fault a significant occurrence and concentration of mass movements were evident at slope angles between 31 40 the preferred orientations of the mass movements were in southerly directions the concentrations of mass movements differ substantially among various geological units mass movements are widely distributed in the miocene murree formation whereas the concentration of mass movements is higher in the cambrian muzaffarabad formation the median mass movement concentration inflicted by the epicentre and the muzaffarabad fault exhibited no significant differences ks 0 505 p 0 961 the results of the pca reveal that the largest variance in mass movement concentration is attributed to the distance from the epicentre and the muzaffarabad fault the findings suggest that the mass movement concentration is primarily dependent on the distance from the earthquake source in addition the topographic parameters and geological units played subordinate roles in the distribution of mass movements

density distribution of landslides triggered by the 2008 wenchuan earthquake and their relationships to peak ground acceleration the distribution of landslides induced by the 2008 m w 7 9 wenchuan earthquake was investigated following the method of meunier et al 2007 to examine the relationships to peak ground acceleration pga results suggest that landslide densities are quantifiably related to pga thresholds of pgacr for landslide failure are graphic 1 for average horizontal pga and graphic 2 for average vertical pga as with other earthquakes the distribution of the wenchuan earthquake triggered landslides can be described by two equations based on area and source densities respectively the similar damping factors of 20 in these two equations suggest that both density distribution patterns of landslides reflect the dissipation of seismic energy landslide derived pga equations were then produced for the hanging wall region of the earthquake affected area the results indicate that it should be possible to produce an earthquake shake map from the distribution of earthquake triggered landslides in an area where there are few or no seismic instruments but many landslides 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif

stability analysis of three dimensional seismic landslides using the rigorous limit equilibrium method abstract in this paper a new method combining the rigorous limit equilibrium method and the pseudo dynamic method is proposed to investigate stability of 3d seismic landslides in which the force equilibrium conditions along three coordinate axes and the overall moment equilibrium conditions around three coordinate axes are all strictly satisfied moreover sinusoidal cosinusoidal wave is applied to simulate earthquake displacement and an amplification factor of peak seismic acceleration is referred to as the amplification of seismic wave when it propagates from the bottom to the top of landslides the pseudo dynamic factor of safety of 3d seismic landslides is determined using trust region reflective iterative algorithm the effects of the parameters of the seismic landslides on the stability are analyzed by the bp neural network algorithm in which a database to investigate the stability of 3d seismic landslides is established in addition the stability of donghekou landslide is studied to verify the accuracy and precision of the present method

on far field occurrence of seismically induced landslides abstract earthquakes may induce landslides at large distances from the epicentral area in the last two decades there have been many studies of this phenomenon to determine the causes that contribute to the occurrence of landslides at very long distances from earthquake epicenter in this study which is based on previously published works a worldwide database comprising 270 earthquakes including 150 during the instrumental period was compiled to analyse the features of those landslides that occur at much further distances than maximum expected distances from the analysis of the compiled data it was observed that susceptible slopes can be grouped into five broad geological categories jointed rock marly clayey cohesive soils granular alluvial and or colluvial sediments volcanic soils and residual soil slopes these categories were equally likely to be associated with far field disrupted landslides whereas far field coherent landslides were more frequent on cohesive soil slopes other factors along with slope susceptibility may also contribute to far field landslides and increase the size of the area affected among these factors site effects antecedent rain and occurrence of seismic series have been cited the analysis of available data also showed that for events of the same magnitude far field disrupted landslides may occur at greater distances than coherent ones the same database has also been employed to determine for the first time the upper bound curves for the maximum observed epicentral distances of several types of landslides and the maximum area observed to be affected by landslides both based on the epicentral intensity of the events

distribution of landslides along the andean active orogenic front argentinean precordillera 31 33 s abstract as one of the main environmental effects of earthquakes the distribution of landslides could reflect regional neotectonic activity to that end we carried out an inventory of landslides along the precordillera range 31 33 s comprising the most seismically active region of argentina main quaternary deformation is concentrated in this western central part of the country associated with active faults linked to intense shallow seismic activity

the long term evolution of landslide activity near the epicentral area of the 2008 wenchuan earthquake in china abstract the wenchuan earthquake triggered numerous landslides and damaged vast areas of vegetation strong mountain earthquakes have long term impacts on the activities of subsequent landslides it is crucial for long term geohazard risk assessment to investigate the spatio temporal evolution of post earthquake landslides we used multi year images from 2008 to 2018 to track the reactivation of coseismic landslides and newly occurring landslides to evaluate the influence of the wenchuan earthquake on subsequent rain induced landslides with the aid of a gis platform combined with field investigations we analyzed the temporal and spatial evolutions of landslide activities over the past ten years and the factors controlling these changes in addition the process of vegetation recovery at landslide sites in the epicentral area was detected based on multi year landsat tm data after the wenchuan earthquake we observed that the total area of active landslides decreased significantly with time in the first 5 years 2008 2013 the vegetation recovered quickly but was not well rehabilitated and post seismic landslides generally maintained high activity levels due to progressive revegetation and consolidation most of the coseismic deposits along the hillslopes gradually stabilized subsequently 2013 2018 landslide activity weakened and mainly occurred in high and steep areas with poor vegetation recovery particularly in proximity to the drainage network decreasing occurrence of rain induced landslides was closely related to vegetation recovery in both time and space and vegetation recovery could promote the reduction in post earthquake landslide activities we also proposed a quantitative model for the landslide rate in the epicentral area of the wenchuan earthquake which shows that the enhanced landslide rate reached its peak after the earthquake and will decrease to the pre earthquake level in 25 years the evolution of the post seismic landslide activity can be categorized into four stages high active period 2008 2013 low active period 2013 2018 recovery period 2018 2033 and stable period after 2033

statistical analysis of factors affecting landslide distribution in the new madrid seismic zone tennessee and kentucky abstract more than 220 large landslides along the bluffs bordering the mississippi alluvial plain between cairo ill and memphis tenn are analyzed by discriminant analysis and multiple linear regression to determine the relative effects of slope height and steepness stratigraphic variation slope aspect and proximity to the hypocenters of the 1811 12 new madrid mo earthquakes on the distribution of these landslides three types of landslides are analyzed 1 old coherent slumps and block slides which have eroded and revegetated features and no active analogs in the area 2 old earth flows which are also eroded and revegetated and 3 young rotational slumps which are present only along near river bluffs and which are the only young active landslides in the area discriminant analysis shows that only one characteristic differs significantly between bluffs with and without young rotational slumps failed bluffs tend to have sand and clay at their base which may render them more susceptible to fluvial erosion bluffs having old coherent slides are significantly higher steeper and closer to the hypocenters of the 1811 12 earthquakes than bluffs without these slides bluffs having old earth flows are likewise higher and closer to the earthquake hypocenters multiple regression analysis indicates that the distribution of young rotational slumps is affected most strongly by slope steepness about one third of the variation in the distribution is explained by variations in slope steepness the distribution of old coherent slides and earth flows is affected most strongly by slope height but the proximity to the hypocenters of the 1811 12 earthquakes also significantly affects the distribution the results of the statistical analyses indicate that the only recently active landsliding in the area is along actively eroding river banks where rotational slumps formed as bluffs are undercut by the river the analyses further indicate that the old coherent slides and earth flows in the area are spatially related to the 1811 12 earthquake hypocenters and were thus probably triggered by those earthquakes these results are consistent with findings of other recent investigations of landslides in the area that presented field historical and analytical evidence to demonstrate that old landslides in the area formed during the 1811 12 new madrid earthquakes results of the multiple linear regression can also be used to approximate the relative susceptibility of the bluffs in the study area to seismically induced landsliding

the november 17th 2015 lefkada greece strike slip earthquake field mapping of generated failures and assessment of macroseismic intensity esi 07 abstract on november 17 2015 a strong shallow earthquake mw 6 5 occurred on the island of lefkada along a n20 5 e east dipping strike slip fault with right lateral sense of slip the event triggered environmental effects that were mainly mapped at the western part of the island while moving towards the eastern part the severity of the earthquake induced failures decreased the most characteristic geological effects that were triggered by the earthquake were slope failures including rock falls rock slides and landslides the spatial density of the failures follows an exponential increase with slope angle and decreases for values larger than 55 small size liquefaction phenomena such as sand craters and ejection of fine grained sand through ground cracks were documented at the coastal area of vassiliki the epicentral intensity was assessed based on the definitions of environment seismic intensity scale as viii esi 07 and the macroseismic epicenter viii up to ix was located at the coastal area of egremnoi west of athani village south lefkada in addition comparing the severity of earthquake induced failures on the main road network triggered by the 2003 and 2015 events it is concluded that the behavior of the protection measures such as fences and walls could be generally characterized as satisfactory on the contrary the similarity of the structural failures triggered by the 2003 event with the ones triggered by the 2015 earthquake documented at the port of vassiliki indicates that the post 2003 constructed port facilities failed to guarantee the functionality of the port of vassiliki