combining seismic noise techniques for landslide characterization a strong topographic relief and the presence of weakly consolidated sediments create favorable conditions for the development of landslides around the eastern rim of the fergana basin central asia in summer 2012 a field experiment employing small aperture seismic arrays was carried out on an unstable slope using ambient vibration recordings the aim of the study was to constrain the seismic response of a potential future landslide and to map lateral and vertical changes in the shear wave velocity of the surficial soil layers strong variations of horizontal to vertical spectral ratios in terms of amplitude and directionality indicated clear differences in local site effects probably reflecting the stability of different sections of the slope results further showed resonant frequencies of both the entire unstable block as well as for smaller individual parts the use of an ad hoc passive seismic tomography approach based on noise correlograms allowed for the mapping of the shear wave velocities of the sliding material even in cases of significant topography relief based on the recording of seismic noise only we clearly identified a low velocity body of weakly consolidated claystone and limestone material which can be interpreted as the landslide body with laterally varying thickness

using ambient noise to characterise seismic slope response the case of qiaozhuang peri urban hillslopes sichuan china abstract the mw 7 9 wenchuan earthquake of may 12th 2008 shattered and induced failures on hillslopes surrounding the centre of the town of qiaozhuang located 250 km ne of the mainshock epicentre this motivated investigations on the possible occurrence of site amplification phenomena the initial efforts involved a temporary accelerometer monitoring carried out between april and october 2009 on weigan hill and mount dong located sw and ne of the qiaozhuang centre respectively the monitoring results revealed that the local geological setting characterised by silurian phyllites with sub vertical schistosity at weigan and by fractured precambrian limestones at dong exert major influence on the slopes resonance phenomena with a secondary contribution due to the topographic setting to extend the investigation on local slope response a series of ambient noise recordings were conducted at several sites of the two hills as well as at mount shizi located nw of the town centre which is topographically and geologically similar to mount dong the focus was on the sites monitored by accelerometer stations whose seismic records provided the opportunity to validate the outcomes of ambient noise analysis noise data were analysed using two approaches the standard nakamura s method and a new technique based on analysis of instantaneous polarization properties aimed at estimating ellipticity of rayleigh waves data interpretation was hampered by a contingent factor i e environmental conditions characterised by a strong persistent e w polarized noise at low frequencies below 1 hz and by the complex of geologic and geomorphic conditions the latter particularly in the case of weigan hill appear responsible for a considerable amplification of vertical ground motions the repeated recordings and the comparison of the outcomes of the two techniques of noise analysis with the accelerometer data showed that the new technique provides more stable and consistent results furthermore the new technique was able to reveal site resonance properties that nakamura s method fails to recognise because of transient overlapping of different type waves overall the ambient noise analysis provided evidence of i low frequency resonance 1 hz acting at the scale of the entire relief on weigan hill ii directional amplifications at intermediate frequencies 4 hz affecting ridge crests made of fractured limestone on mounts dong and shizi and iii higher frequency resonances 7 20 hz which vary at a very local scale this information is relevant for inferring the susceptibility of local slopes to earthquake induced failures and hence for the collateral seismic hazard assessment in the qiaozhuan peri urban areas

ambient vibration analysis of an unstable mountain slope summary a field experiment with small aperture seismic arrays was performed on the unstable rock slope above the village of randa in the southern swiss alps the aim of this experiment was to constrain the seismic response of a potential future rockslide using ambient vibration recordings weak seismic events were identified on the recordings and site to reference spectral ratios were calculated using a reference site located on the stable part of the slope spectral ratios of up to 30 were observed at sites located within the unstable portion of the slope a strong variation of spectral ratios with azimuth indicates a directional site effect neither amplification nor directionality were observed at sites located in the stable part of the slope furthermore time frequency polarization analysis of the ambient noise was performed to provide robust estimates of frequency dependent directions of the maximum polarization it was found that the unstable part of the slope vibrates within a narrow range of directions 130 10 for the frequency range centred around 5 hz the polarization directions estimated from ambient seismic vibrations are in good agreement with the deformation directions obtained by geodetic and in situ measurements no directionality of ambient vibrations was observed at sites within the stable part of the slope

a parametric numerical study of the interaction between seismic waves and landslides for the evaluation of the susceptibility to seismically induced displacements this study presents the results of a numerical analysis investigating the influence of the interaction between seismic waves and slopes on seismically induced displacements of existing landslides three step like slope geometries with dip angles varying from 10 degrees to 45 degrees and two landslide mechanisms were considered 54 multi frequential dynamic equivalent signals were applied to the models and were derived according to the lema des approach based on the accelerometric records of the european strong motion and cosmos databases the simulations were performed using a finite difference approach that assumed different viscous rheologies and considered different values for both the dynamic properties and the mechanical parameters the interaction between seismic waves and landslides was analyzed using frequency ratios defined for characteristic periods associated with the landslide dimensions i e thickness and length and the seismic input a regression analysis was also performed to derive correlations between seismically induced displacements and the frequency ratios the values of the arias intensity and the critical accelerations the obtained results reveal that a the seismically induced displacements increase with the seismic amplification induced by the landslide mass b the coupling of a 2d interaction between seismic waves and slope with the 1d resonance of the landslide mass which is strictly related to the high impedance contrasts between the landslide mass and the substratum significantly affects the seismically induced displacements and c the seismically induced displacements increase more intensely with increasing slope angle for a rototranslational mechanism with respect to a translational one moreover the seismically induced displacements that can be expected from the here obtained results can significantly differ from those computed by the sliding block stability analyses based on newmark s method

geological hazards in loess terrain with particular reference to the loess regions of china abstract the considerable morphodynamic energy provided by the continuing tectonic evolution of asia is expressed in high erosional potentials and very high rates of sediment production that make this continent unequalled as a terrestrial source of primary silt many of these environments are hazardous threatening human occupation health and livelihood especially in regions of dense population such as the loess lands of north china dry loess can sustain nearly vertical slopes being perennially under saturated however when locally saturated it disaggregates instantaneously such hydrocompaction is a key process in many slope failures made worse by an underlying mountainous terrain of low porosity rocks gully erosion of loess may yield very high sediment concentrations 60 by weight characteristic vertical jointing in loess influences the hydrology enlarged joints develop into natural sub surface piping systems which on collapse produce a loess karst terrain collapsible loess up to 20 m thick is common on the western loess plateau foundation collapse and cracked walls are common many rapid events following periods of unusually heavy monsoonal rain slope failure is a major engineering problem in thick loess terrain flow slide and spread types being common the results are often devastating in both urban and rural areas an associated hazard is the damming of streams by landslides the human population increases the landslide risk in china notably through imprudent land use practices including careless water management a number of environmentally related endemic diseases arise from the geochemistry of loess and its groundwaters including fluorosis cretinism kaschin beck disease keshan disease and goitre the chinese desert margins also have a major atmospheric dust problem the effect of such dust upon human health in these extensive regions including many large cities has yet to be evaluated but pneumoconiosis is thought to affect several million people in north and west china

late devonian glaciation in south america abstract an ice age in famennian late devonian time is documented by the presence of diamictites with striated faceted and polished pebbles rhythmites with dropstones erratic boulders and striated pavements and deformed sandstones the glacigenic beds occur in three huge intracratonic basins solimoes amazonas and parnaiba and in one pericratonic basin acre in northern brazil other possible late devonian diamictites may occur elsewhere in brazil and africa which if confirmed would extend considerably the area affected by this glacial age the onset of the late devonian glaciation caused a global narrowing of the warm climatic belts sharp regression increased clastic sedimentation massive biotic extinction reduced biochemical deposition and unconformities this resulted in important facies changes in the world geological record ice centers moved from northern africa to southwestern south america from late ordovician to early silurian time from mid silurian to early late devonian time no record of glaciation is known in late late devonian time intermittent glaciation began again in central south america and from late late devonian to early late permian time ice centers migrated towards antarctica across south america and south africa the devonian and ordovician silurian glaciations together with the better known permo carboniferous glaciations may all have primarily resulted from the shifting position of the gondwana continent with respect to the south pole

carboniferous and early permian biogeography during the carboniferous changes in the biogeographical distribution of shelf dwelling benthic marine invertebrates were made in response to changes in physical paleogeography and climatic variations calcareous foraminifers and bryozoans are principal examples of the general trends during the early carboniferous which show that tournaisian and early and middle visean faunas were broadly cosmopolitan in a circumequatorial belt and that latitudinal diversity gradients were relatively minor during the later part of the visean and early part of the namurian the hercynian orogeny caused by the collision of euramerica with gondwana disrupted these cosmopolitan equatorial faunal patterns this was also a time of progressively cooler temperatures throughout the world of dramatic reduction in faunal diversity and of high rates of extinction of both species and genera during middle carboniferous time strongly provincial faunas were common spasmodic but limited dispersals gave a few widespread genera significantly different stratigraphic ranges in different provinces so that tethyan and non tethyan distributions are recognizable faunal diversity gradually increased during the middle carboniferous and then declined at the end of the epoch with additional high levels of extinction of species and genera during late carboniferous time several new faunal lineages became well established some filled vacant ecological niches however others took advantage of the increase in the number of niches that became available because of gradually warming climates provinciality continued to be pronounced diversity gradually increased and continued to do so through the early permian

ambient vibration classification of unstable rock slopes a systematic approach abstract in this paper we are comparing the seismic response of 25 different rock slope instabilities with diverse geological properties activity level failure mechanism fracturing and volumes we classify them according to their dynamic behaviour in the dataset we found two main classes of unstable rock slopes depth controlled sites and volume controlled sites for depth controlled instabilities the seismic wavefield is controlled by horizontally propagating surface waves in the highly fractured and weathered material at such sites surface wave dispersion curves can be retrieved and inverted into velocity profiles of the underground the lateral borders of depth controlled instabilities are not obvious and the seismic properties mainly change with depth the seismic response of volume controlled sites is dominated by the eigenvibrations of the rock mass itself such instabilities have clear lateral and vertical borders and show highly amplified ground motion in limited frequency bands the observed polarisation of the ground motion is perpendicular to deep open fractures that do not allow surface waves to propagate a special case of the volume controlled sites is represented by tower like rock masses showing strong amplification and directionality their dynamic behaviour might not only be related to the internal structure but also to their geometry that is similar to high rise buildings another type of rock instabilities is represented by block structures which are difficult to identify by the proposed ambient vibration methods a clear relation between geological properties and seismic response was not found

unconventional pseudostatic stability analysis of the diezma landslide granada spain based on a high resolution engineering geological model abstract a novel unconventional pseudostatic analysis is proposed here to infer on the sensitivity of a landslide to earthquakes characterized by different physical properties several sine waves with different amplitudes frequencies and phases were applied to the landslide mass assuming limit equilibrium conditions the unconventional approach was used for the diezma landslide case study the landslide is located 25 km from the city of granada spain although the slope had repeatedly suffered small scale stability problems since the construction of the a 92 highway a larger failure occurred on 18 march 2001 and damaged the highway between kilometers 272 6 and 272 8 the landslide had an estimated volume of 1 2 mm 3 and involved a disordered deposit of silt and clay with heterometric blocks within the numidoide formation which outcrops along the contact between the malaguide and dorsal domains of the betic cordillera mountain range despite the 18 million euros spent since 1999 on geotechnical investigations and stabilization solutions the numerous reactivations that occurred through 2010 and 2013 demonstrate the persistent activity of the landslide the geometry of the large slope failure corresponding to the first activation of the diezma landslide was used to back analyze the stability of the slope based on a high resolution engineering geological model the model was developed from the analysis of numerous borehole logs as well as from geophysical investigations consisting of seismic noise measurements the results demonstrate that the safety factor sf of the diezma landslide varies significantly for frequencies less than 1 hz moreover unstable conditions are reached at frequency values between 0 5 and 1 hz for water pressure distributions corresponding to bishop factors r u between 0 and 0 36 to estimate the co seismic displacements the geometrical and mechanical properties of the landslide mass were used to derive its characteristic periods for thickness t s and length t l which were compared with the characteristic period of the earthquake t m the results indicate that the maximum expected co seismic displacements are up to 2 m for an earthquake with a t m value close to 1 s and an arias intensity on the order of 1 m s

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

the effects of normal and shear stress wave phasing on coseismic landslide displacement predictive models used to assess the magnitude of coseismic landslide strain accumulation in response to earthquake ground shaking typically consider slope parallel ground accelerations only and ignore both the influence of coseismic slope normal ground accelerations and the phase relationship between dynamic slope normal and slope parallel accelerations we present results of a laboratory study designed to assess the significance of the phase offset between slope normal and slope parallel cyclic stresses on the generation of coseismic landslide displacements using a dynamic back pressured shearbox that is capable of simulating variably phased slope normal and slope parallel dynamic loads we subjected sediment samples to a range of dynamic loading scenarios indicative of earthquake induced ground shaking we detail the variations in strain accumulation observed when slope normal and slope parallel stresses occur independently and simultaneously both in and out of phase using a range of dynamic stress amplitudes our results show that the instantaneous phasing of dynamic stresses is critical in determining the amount of coseismic landslide displacement which may vary by up to an order of magnitude based solely on wave phasing effects instantaneous strain rate is an exponential function of the distance normal to the mohr coulomb failure envelope in plots of shear stress against normal effective stress this distance is strongly controlled by the phase offset between dynamic normal and shear stresses our results demonstrate that conditions considered by conventional coseismic slope stability models can either overestimate or underestimate earthquake induced landslide displacement by up to an order of magnitude this has important implications for accurate assessment of coseismic landslide hazard

discussion of eocene to mid pliocene landscape evolution in scandinavia inferred from offshore sediment volumes and pre glacial topography using inverse modelling pederen et al 2018 geomorphology 303 467 485 abstract pedersen et al 2018 use offshore sediment volumes to carry out inverse modelling of the scandinavian landscape during the cenozoic close inspection of the source area s for the sediment volume used in the study reveals that multiple source areas were responsible for the sediments fringing scandinavia in addition to a much more complex origin of the sediments than just scandinavia no consideration about the caliber of the sediments transport media maturation of the sediments and climate is included in the modelling by pedersen et al 2018 the study exposes a large gap between geological observations and modelling

geophysical investigation and dynamic modelling of unstable slopes case study of kainama kyrgyzstan summary the presence of massive quaternary loess units at the eastern border of the fergana basin kyrgyzstan central asia makes this area particularly prone to the development of catastrophic loess earthflows causing damages and injuries almost every year efficient disaster management requires a good understanding of the main causes of these mass movements that is increased groundwater pressure and seismic shaking this paper focuses on the kainama earthflow mainly composed of loess which occurred in 2004 april its high velocity and the long run out zone caused the destruction of 12 houses and the death of 33 people in summer 2005 a field survey consisting of geophysical and seismological measurements was carried out along the adjacent slope by combination and geostatistical analysis of these data a reliable 3 d model of the geometry and properties of the subsurface layers as shown in the first part of the paper was created the analysis of the seismological data allowed us to point out a correlation between the thickness of the loess cover and the measured resonance frequencies and associated amplification potential the second part of this paper is focused on the study of the seismic response of the slope by numerical simulations using a 2 d finite difference code named flac modelling of the seismic amplification potential along the slope confirmed the results obtained from the seismological survey strong amplifications at the crest and bottom of the slope where there is a thick loess cover and almost no amplification in the middle part of the slope furthermore dynamic slope stability analyses were conducted to assess the influence of local amplifications and increased groundwater pressures on the slope failure the results of the dynamic modelling although preliminary show that a combination of seismic and hydrologic origin pore pressure build up during the seismic shaking is the most probable scenario responsible for the 2004 failure

application of a characteristic periods based cpb approach to estimate earthquake induced displacements of landslides through dynamic numerical modelling the authors would like to thank the european union erdf for financial support via the monitorizacion sismica de deslizamientos criterios de reactivacion y alerta temprana project of the programa operativo feder de andalucia 2007 2013

tien shan geohazards database earthquakes and landslides abstract in this paper we present new and review already existing landslide and earthquake data for a large part of the tien shan central asia for the same area only partial databases for sub regions have been presented previously they were compiled and new data were added to fill the gaps between the databases major new inputs are products of the central asia seismic risk initiative casri a tentative digital map of active faults even with indication of characteristic or possible maximum magnitude and the earthquake catalogue of central asia until 2009 that was now updated with usgs data to may 2014 the new compiled landslide inventory contains existing records of 1600 previously mapped mass movements and more than 1800 new landslide data considering presently available seismo tectonic and landslide data a target region of 1200 km e w by 600 km n s was defined for the production of more or less continuous geohazards information this target region includes the entire kyrgyz tien shan the south western tien shan in tajikistan the fergana basin kyrgyzstan tajikistan and uzbekistan as well as the western part in uzbekistan the north easternmost part in kazakhstan and a small part of the eastern chinese tien shan for the zones outside kyrgyzstan and tajikistan only limited information was available and compiled on the basis of the new landslide inventory and the updated earthquake catalogue the link between landslide and earthquake activity is analysed first size frequency relationships are studied for both types of geohazards in terms of gutenberg richter law for the earthquakes and in terms of probability density function for the landslides for several regions and major earthquake events case histories are presented to outline further the close connection between earthquake and landslide hazards in the tien shan from this study we concluded first that a major hazard component is still now insufficiently known for both types of geohazards and even totally unknown for most giant landslides the time information thus dating rockslides and any large mass movement is a crucial factor in order to better constrain related hazards second we highlight the role of coupled hazards in the tien shan inside the mountain range the largest disasters were caused by earthquake triggered landslides and massive earth flows therefore it is of prime importance for these mountain regions to complement single hazard assessment by coupled hazard scenarios on the basis of these scenarios risk evaluations may then be completed considering direct impacts on artificial dams hydropower schemes mining and road infrastructure as well as remote effects from possible dam breaches and mobilisation of mining and nuclear waste storages basic hazard and risk components are partly analysed in this paper and partly in a companion paper tien shan geohazards database landslide susceptibility and impacts

development of the late paleozoic glaciations of the south american gondwana in western argentina abstract the late paleozoic ice age in the south american segment of gondwana consisted of several glaciations which can be grouped into two main glacial periods the oldest of them occurred in late early to early late carboniferous time and the younger in early permian time paleontological evidence in the western argentine precordillera supports a late visean age for the beginning and a probable early westphalian age for the end of the carboniferous glacial period in this span of time subsidence and deposition of glacial debris took place in the western mobile belt and in patagonia but no sediments of that age were deposited in the eastern portion of the south american gondwana where subsidence started later a carboniferous glacial sequence is remarkably well preserved in the san eduardo group on the western flank of the precordillera where at least three distinct glaciations are recognized this sequence can be taken as a reference section for the carboniferous glacial deposits shorter than the former and probably restricted to the asselian epoch the permian glacial period is better known the evidence for it is well developed in eastern south american gondwana although a relic is also present in the precordillera the recognition of two glacial periods within the late paleozoic ice age is supported by the existence of a long lasting interglacial which seemingly began in the late westphalian and lasted until the end of the carboniferous period this major interglacial period is inferred from the total absence of glacial features in the upper carboniferous sequences in spite of the existence of a mountainous belt parallel to the pacific during the carboniferous period the presence of marine beds and glacial drift well to the east of these ranges suggests that it was not altitude that was the main factor in determining the formation of glaciers but latitude plus a global change in temperature it is argued that the ice sheets extended greatly during the carboniferous glaciations and reached neighboring areas of the paganzo basin in central argentina

the interaction of seismic waves with step like slopes and its influence on landslide movements abstract the interaction of seismic waves with slopes is a major factor influencing landslide movements that involve slope stability local site seismic amplification and topographic effects affecting ground motion the results of a numerical study of landslide movements induced by the interaction of seismic waves with step like slopes are presented here to investigate this input slope interaction a dynamic analysis was performed using the finite difference stress strain numerical code flac 6 0 under visco plastic conditions the dynamic signals were selected to be representative of different peak ground accelerations pgas arias intensities and frequency contents and they were used in a parametric study of different step like slopes with different geometrical configurations in terms of dip height and thickness of geological strata the derived outputs were processed for a seismic amplification analysis and to evaluate the induced stress strain effects in terms of progressive failure and resulting displacements the obtained results i describe a fundamental role of topography in amplifying or de amplifying the seismic ground motion ii demonstrate that the progressive failure of unsheared slopes influences the seismic amplification iii show that the strain effects on unsheared slopes in terms of progressive failure are more intense with increasing arias intensity and slope dip iv prove that amplification or de amplification processes can justify the values of displacements involving pre existing landslide masses which are significantly different with respect to those expected on the basis of sliding block approaches i e newmark s and flexible sliding block methods v highlight that in the geological setting considered here the seismically induced displacements arising from the reactivation of pre existing landslide masses can be significantly underestimated by sliding block approaches in the case of low angle slopes characterised by high k values i e the ratios between the critical pseudostatic threshold ky of the landslide and pgas of the applied seismic input

deep seated gravitational slope deformation dsgsd and slow moving landslides in the southern tien shan mountains new insights from insar tectonic and geomorphic analysis we investigated deep seated gravitational slope deformation dsgsd and slow mass movements in the southern tien shan mountains front using synthetic aperture radar sar time series data obtained by the alos palsar satellite dsgsd evolves with a variety of geomorphological changes e g valley erosion incision of slope drainage networks over time that affect earth surfaces and therefore often remain unexplored we analysed 118 interferograms generated from 20 sar images that covered about 900 km2 to understand the spatial pattern of the slope movements and to identify triggering parameters we correlated surface dynamics with the tectono geomorphic processes and lithologic conditions of the active front of the alai range we observed spatially continuous constant hillslope movements with a downslope speed of approximately 71 mm year 1 velocity our findings suggest that the lithological and structural framework defined by protracted deformation was the main controlling factor for sustained relief and consequently downslope mass movements the analysed structures revealed integration of a geological structural setting with the superposition of cretaceous paleogene alternating carbonatic and clastic sedimentary structures as the substratum for younger less consolidated sediments this type of structural setting causes the development of large scale gravity driven dsgsd and slow mass movement surface deformations with clear scarps and multiple crest lines triggered planes for large scale deep mass creeps and these were related directly to active faults and folds in the geologic structures our study offers a new combination of insar techniques and structural field observations along with morphometric and seismologic correlations to identify and quantify slope instability phenomena along a tectonically active mountain front these results contribute to an improved natural risk assessment in these structures

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

s wave velocity measurements applied to the seismic microzonation of basel upper rhine graben summary an extensive s wave velocity survey had been carried out in the frame of a recent seismic microzonation study of basel and the border areas between switzerland france and germany the aim was to better constrain the seismic amplification potential of the surface layers the survey included single station h v spectral ratios and ambient vibration array measurements carried out by the swiss team as well as active s wave velocity measurements performed by the german and french partners this paper is focused on the application of the array technique which consists in recording ambient vibrations with a number of seismological stations several practical aspects related to the field measurements are outlined the signal processing aims to determine the dispersion curves of surface waves contained in the ambient vibrations the inversion of the dispersion curve provides a 1 d s wave velocity model for the investigated site down to a depth related to the size of the array since the size of arrays is theoretically not limited arrays are known to be well adapted for investigations in deep sediment basins such as the upper rhine graben including the area of the city of basel in this region 27 array measurements with varying station configurations have been carried out to determine the s wave velocity properties of the geological layers down to a depth of 100 250 m for eight sites the outputs of the array measurements have been compared with the results of the other investigations using active sources the spectral analysis of surface waves sasw and s wave reflection seismics borehole information available for a few sites could be used to calibrate the geophysical measurements by this comparison the advantages and disadvantages of the array method and the other techniques are outlined with regard to the effectiveness of the methods and the required investigation depth the dispersion curves measured with the arrays and the sasw technique were also combined and inverted simultaneously to use the advantages of both methods finally the paper outlines and discusses the contribution of the s wave velocity survey to the new seismic microzonation of the basel region in this regard one major outcome of the survey is the quantification of vertical and lateral changes of the s wave velocity due to changing lithology or changing compaction and degree of weathering of the layers

on the seismic response of deep seated rock slope instabilities insights from numerical modeling abstract earthquake induced landslides constitute a critical component of seismic hazard in mountainous regions while many seismic slope stability analysis methods exist with varying degrees of complexity details of interactions between seismic waves and incipient landslides are not well understood and rarely incorporated in particular for deep seated slope instabilities we present a series of 2d distinct element numerical models aimed at clarifying interactions between earthquakes and large rock slope instabilities the study has two main goals 1 to explore the role of amplification in enhancing co seismic slope deformation a relationship widely discussed in literature but rarely tested quantitatively and 2 to compare our numerical results with the well established newmark method which is commonly used in seismic slope stability analysis we focus on three amplification phenomena 1 geometric topographic amplification 2 amplification related to material contrasts and 3 amplification related to compliant fractures slope height topography seismic velocity contrasts and internal strength and damage history were varied systematically in a series of models with a relatively simple scalable geometry for each model we compute the spatial amplification patterns and displacement induced by real earthquake ground motions we find that material contrasts and internal fracturing create both the largest amplification factors and induced displacements while the effect of geometry is comparably small newmark type sliding block methods underestimate displacements by not accounting for material contrasts and internal fracturing within the landslide body both common phenomena in deep seated slope instabilities although larger amplification factors tend to be associated with greater displacements we did not identify a clear link between ground motion frequency content spectral amplification and induced displacement nevertheless observation of amplification patterns can play an important role in seismic slope stability analyses as 1 strong amplification related to material contrasts or compliant fractures is an indicator of potentially large co seismic displacements and 2 amplification patterns can be used to constrain geological and numerical models used for seismic stability analysis the complexity of wave slope interactions as well as the potential to severely underestimate hazard using newmark type methods motivates use of rigorous numerical modeling for quantitative seismic hazard and risk assessment of large landslides

rainfall patterns and the distribution of coals and evaporites in the mesozoic and cenozoic abstract paleoclimatologists have adequately demonstrated over the last twenty years that the distribution of climatically sensitive sediments can be related to present day climatic zones that are roughly parallel to latitude for example coals were deposited at paleolatitudes that correspond to the present day rainy zones at the equator and at about 55 n and 55 s indicating that those zones were present in the past from this it can be concluded that atmospheric circulation has not been radically different from its present configuration despite some apparently great differences in some climatic parameters such as the equator to pole temperature gradient nevertheless the zonal model for predicting the distribution of climatically sensitive sediments is not wholly adequate although general atmospheric circulation may not have been radically altered from its present pattern it would have differed in some respects because the paleogeography was different from the present geography therefore we have constructed what we believe are more realistic maps of the distribution of rainfall through time these maps are based on maps of atmospheric circulation that have been successfully used to predict the distribution of some petroleum source beds and phosphorites we have compared the predicted distribution of rainfall to the distribution of coals and evaporites for each of seven geologic stages the circulation rainfall maps were more successful than the zonal model for predicting the distribution of evaporites and coals for times when the paleogeography would have maximized the development of a monsoonal circulation which most effectively disrupts the general zonal pattern for times when a monsoonal circulation would not have been important the zonal model adequately predicted the distribution of these rocks

climate of the late devonian to triassic abstract remarkable changes are apparent in climate during late devonian triassic times mostly the climate was rather different from the present the faunas and floras offer much evidence for understanding the climate but in turn understanding the palaeogeography of the faunas and floras is dependent on understanding the climate and the changes in climate the late devonian apparently had a warm climate the climate of the early carboniferous was warm and equable no cold climate can be identified and apparently no ice was present at the poles even a cold temperate climate is difficult to identify on the other hand the tropical zone does not appear to have been particularly hot apparently this reflects an ocean current system and a weather system different from the present ones during the late carboniferous the world became colder and the faunas and floras more provincial ice probably mountain ice appeared in boreal and austral regions widespread glaciation occurred in the earliest permian but it had a very assymetrical character whether continental ice sheets like those of the pleistocene were present is not proven during the early permian the world became warmer probably with some fluctuation in climate and with evidence for seasonal ice but not for glaciers during the late permian the warming continued and a new kind of provincialism developed within the broad tropical and subtropical zone by the end of the permian the earth was very warm in the early triassic no equatorial humid zone can be identified and whereas the tropical zone was hotter than at present the polar zones were also warm the early triassic appears to have been almost universally dry the climate remained warm during the middle and late triassic but humid zones can be recognized the climate also showed some apparent assymetry the pecularities of the climate and the change of climate in this interval of time are not readily explainable either on the basis of the present climate or the present or a similar distribution of land and sea nor are they readily explainable on reconstructions commonly accepted such as pangaea formed in the carboniferous as is often claimed probably more basic data are required before any satisfactory explanations are possible and as well as terrestrial effects including a change in the angle of the earth s rotation extra terrestrial planetary and galactic effects require study

the nature origin and accumulation of loess abstract loess can be defined simply as a terrestrial clastic sediment composed predominantly of silt size particles which is formed essentially by the accumulation of wind blown dust there are three fundamental requirements for its formation 1 a sustained source of dust 2 adequate wind energy to transport the dust and 3 a suitable accumulation site most loess has been modified to some degree by local reworking bioturbation and syn depositional weathering but a process of loessification is not necessary for a dust deposit to qualify as loess the terms primary loess and secondary loess have previously been used to described wind deposited loess and redeposited loess respectively but it is more accurate to describe material reworked and redeposited by non aeolian processes as loess derived colluvium or loess derived alluvium during the quaternary loess formed in three main situations 1 mid continental shield areas beyond the limits of ice sheets periglacial loess 2 on the margins of high mountain ranges perimontane loess and 3 on the semi arid margins of some lowland deserts peridesert loess peridesert loess is relatively poorly developed partly due to the limited efficiency of silt generating mechanisms in low land deserts compared with glaciation but also important is the tendency in arid areas for dust to be dispersed over a wide area and to be rapidly reworked after deposition particularly in areas which experience frequent climatic changes the remarkably thick loess of china and central asia results from an unusual combination of conditions which has persisted for much of the last 2 3 million years namely rapid uplift of the tibetan plateau and surrounding mountain ranges high rates of sediment production and supply to adjacent basins a strong northwesterly and westerly wind regime and the existence of effective dust traps downwind of the source regions

ambient seismic noise tomography of a loess high bank at dunaszekcső hungary loess high banks along the right side of the danube in hungary are potential subjects of landslides small scale ambient seismic noise tomography was used at the dunaszekcs high bank the aim of the study was to map near surface velocity anomalies since we assume that the formation of tension cracks which precede landslides are represented by low velocities mapping rayleigh wave group velocity distribution can help to image intact and creviced areas and identify the most vulnerable sections the study area lies at the top of the castle hill of dunaszekcs which was named after castellum lugio a fortress of roman origin the presently active head scarp was formed in april 2011 and our study area was chosen to be at its surroundings cross correlation functions of ambient noise recordings were used to retrieve the dispersion curves which served as the input of the group velocity tomography phase cross correlation and time frequency phase weighted stacking was applied to calculate the cross correlation functions the average rayleigh wave group velocity at the loess high bank was found to be 171 ms 1 the group velocity map at a 0 1 s period revealed a low velocity region whose location coincides with a highly creviced area where slope failure takes place along a several meter wide territory another low velocity region was found which might indicate a previously unknown loosened domain the highest velocities were observed at the supposed remnants of castellum lugio

amplification of seismic response of a large deep seated landslide in tokushima japan abstract to better understand seismic site responses of deep seated landslides we carried out long term seismic monitoring of a target landslide reactivated by a rainstorm in 2004 accompanying typhoon namtheun in naka town tokushima prefecture japan five seismometers with high sensitivity were installed at different locations on landslide areas with different elevations by examining numerous records of earthquake events we distinguished the effects of material contrast and topography on these localized amplifications for different areas and summarized their features with help of detailed geological and geophysical surveys to analyze differences in amplification the hvsr method calculating the horizontal to vertical spectral ratio of ground motion was applied the amplification on a landslide block with an hvsr peak amplitude smaller than 5 and resulting from topography is predominantly perpendicular to the direction of elongation of the mountain ridge however the amplification revealed by hvsr peak amplitude of 3 to 5 resulting from material contrasts in multiple strata showed differing amplification directions by examining the relationship between the hvsr peak amplitude and shear velocity profiles we found that the amplifications at different frequencies are greatly affected by the extent of material contrasts this may explain why the toe part of the slope with ancient landslide deposits generally shows the greatest ground motion characterized by hvsr peak amplitude normally 10 this type of strong amplification due to material contrasts may result in severe damage to residential areas in mountainous areas during an earthquake and should be considered for the construction of buildings on landslide areas

composite mechanism of the buyukcekmece turkey landslide as conditioning factor for earthquake induced mobility abstract earthquake induced displacements of landslides are significantly conditioned by their 1d and 2d interactions with seismic waves as currently proven by several studies nevertheless the role of a more complex geological setting responsible for a heterogeneous composition of the landslide mass can significantly influence these phenomena the heterogeneity can also depend on multiple phases of the landslide activity responsible for dislodging the whole landslide mass into submasses each one delimited by secondary scarps and characterized by individual mobility hence in the framework of the european project marsite marmara supersite new directions in seismic hazard assessment through focused earth observation in the marmara supersite the buyukcekmece landslide located approximately 30 km w of istanbul turkey was considered as a case study this landslide involves a large mass of approximately 140 million cubic metres composed of silty clays tuffs and sands ascribable to cenozoic geological formations the landslide is characterized by multiple phases of activity with a composite rototranslational mechanism which created seven submasses delimited by secondary scarps the scheme of water circulation in the landslide slope based on piezometer data as well as on a geological survey accounts for two flow nets the first shallower flow net is located in superficial sandy deposits outcropping in the dislodged landslide submasses the second deeper flow net is located in the main sliding surface a slope stability analysis following a global limit equilibrium approach provided a distribution of the pseudostatic coefficient vs pore water pressure the results show that the stability of the landslide submasses increases moving downslope and reactivations are expected in the case of earthquakes with a return period between 475 and 2475 yr according to the local seismic hazard dynamic numerical modelling was also performed using the stress strain finite difference code flac 7 0 to derive the distributions of horizontal displacements vs characteristic period ratios defined as the period due to depth ts and total length tl of the landslide mass over the earthquake characteristic period tm the obtained results indicate that an effective characteristic period of the landslide tl related to the length of a single counter slope tilted submass can provide a more correct explanation for the effect of seismic wave interactions on earthquake induced displacements this result indicates that the earthquake induced mobility of the buyukcekmece landslide is strongly conditioned by its composite rototranslational mechanisms in general these results indicate that landslide evolution can induce a change over time for the characteristic periods related to the dimensions of the dislodged landslide portions and then modify its interactions with seismic waves

instrumental evidence of normal mode rock slope vibration summary a unique field experiment was performed to constrain the seismic response of a large potentially unstable rock slope in the southern swiss alps small aperture seismic arrays were deployed to record ambient vibrations both inside and outside of the mapped instability boundary the recordings were analysed by means of the high resolution f k method site to reference spectral ratios and time frequency dependent polarization analysis all three methods indicated that the wavefield within the potentially unstable rock mass is dominated by normal mode motion standing waves rather than horizontal propagation of seismic waves both fundamental frequency and relative amplification could be recovered from ambient noise data the observed amplification is strongly directional and the maximum amplification is oriented perpendicular to open tension cracks mapped at the ground surface our results highlight site response characteristics relevant for analysis of earthquake triggered rock slope failures

major element geochemistry and paleoclimatology of the permo carboniferous glacigene dwyka formation and postglacial mudrocks in southern africa abstract a chemical index of alteration cia is used to quantify the degree of weathering of fine grained materials in the glacigenic permo carboniferous dwyka formation and succeeding stratigraphic units of southern africa diamictites in the dwyka formation have low cia values compatible with their glacigenic origin interbedded mudrocks show a wide scatter of values suggesting that at least some of them were deposited during periods when ice had retreated from the source areas samples from the prince albert shale which immediately overlies the dwyka formation show high cia values suggesting a rapid transition to a much more intensive weathering regime warmer climatic conditions samples from the succeeding whitehill shale have a low average value so that weathering was once more inhibited perhaps by a temporary return to a colder climate the highest stratigraphic units sampled the upper shales have an average cia value comparable to that of average shales and suggesting normal weathering conditions major element geochemical data can supplement sedimentological and paleontological information and provide a valuable contribution to the detailed paleoclimatic interpretation of such glacigenic successions

geophysical survey to estimate the 3d sliding surface and the 4d evolution of the water pressure on part of a deep seated landslide geophysical surveys were conducted on the very unstable front part of the la clapiere landslide in the french alps alpes maritimes the electrical resistivity survey was carried out to obtain for the first time on this deep seated landslide 3d information on the slipping surface and the vertical drained faults moreover we planned to follow within time 6 months the evolution of the saturated zones presence of gravitational water and their percolation into the shearing zones our 4d results showed the importance of the complex water channelization within the slope and relation to geological discontinuities

derivation of long term spatiotemporal landslide activity a multi sensor time series approach abstract this paper presents a remote sensing based method to efficiently derive multi temporal landslide inventories over large areas which allows for the spatiotemporal analysis of landslide activity which is an important prerequisite in systematic regional landslide hazard and risk assessment the developed method uses globally archived satellite remote sensing data for a retrospective systematic assessment of past multi temporal landslide activity landslides are automatically identified as spatially explicit objects based on landslide specific vegetation cover changes using temporal ndvi trajectories and complementary relief oriented parameters to enable the long term analysis of large areas with highest possible temporal resolution the developed method facilitates the use of a large amount of optical multi sensor time series data the database of this study consists of 212 datasets that comprise freely available landsat tm etm data and spot 1 5 irs1 c lissiii aster and rapideye data these data were acquired between 1986 and 2013 and cover a landslide prone area of 2500 km 2 in southern kyrgyzstan we identified 1583 landslide objects ranging in size between 50 m 2 and 2 8 km 2 spatiotemporal analysis of the landslides that were detected during these 27 years reveals continuous landslide activity of varying intensity the highest overall landslide rates occurred in 2003 and 2004 exceeding the long term annual average rate of 57 landslides per year by more than a factor of five the areas of highest landslide activity are also determined whereas most of these areas were persistent over time

comprehensive analysis of the local seismic response in the complex buyukcekmece landslide area turkey by engineering geological and numerical modelling multi risk management requires a strong comprehension of possible effects induced by natural hazardous events in this regard landslides triggering due to earthquakes results from complex interactions between seismic waves and slopes multidisciplinary approaches can significantly contribute to better understand such interactions the large buyukcekmece landslide about 1500 m wide and 1830 m long located in turkey avcilar peninsula about 15 km northward from the north anatolian fault zone nafz was selected as case study in the framework of the european project marsite marmara supersite new directions in seismic hazard assessment through focused earth observation in the marmara supersite the avcilar area was recently affected by the 17th august 1999 mw 7 4 kocaeli and by the 12th november mw 7 2 duzce earthquakes the buyukcekmece landslide involves upper oligocene to lower miocene deposits consisting of silty clays tuffs and sands no earthquake induced re activations are testified so far but the landslide area was interested by a very intense urbanization during the last decade a detailed engineering geological model for the local seismic response of the buyukcekmece landslide slope was constructed based on geophysical measurements data from a multisensor in hole monitoring system and stress strain numerical modelling several tens of earthquakes were recorded from october 2014 to may 2015 in the landslide site by considering in hole and surface data the reliability of the local seismic response obtained by numerical modelling respect to the empirically derived one was checked in terms of both site to reference spectral ratios and transfer function between surface and downhole sites inside the landslide mass the 2d numerical amplification functions confirm that the local seismic response is a consequence of the complex geological setting of the landslide slope while no relevant amplification effects can be referred to topographic features based on these results the interaction between seismic waves and the buyukcekmece landslide slope cannot be neglected to evaluate the possibility of future landslide re activations