upper bound solution for seismic bearing capacity of shallow foundations near slopes an upper bound technique of limit analysis is used to determine the bearing capacity of a shallow strip foundation near a slope the approach used is pseudo static and the seismic forces consist of a horizontal load applied to the foundation and the inertia of the soil mass the failure mechanism is composed of an active wedge a passive wedge and a shear transition zone between the two wedges the results are compared with those of other investigators

seismic bearing capacity of foundations on cohesionless slopes by applying the lower bound theorem of limit analysis in conjunction with finite elements and nonlinear optimization the bearing capacity factor n has been computed for a rough strip footing by incorporating pseudostatic horizontal seismic body forces as compared with different existing approaches the present analysis is more rigorous because it does not require an assumption of either the failure mechanism or the variation of the ratio of the shear to the normal stress along the footing soil interface the magnitude of n decreases considerably with an increase in the horizontal seismic acceleration coefficient kh with an increase in kh a continuous spread in the extent of the plastic zone toward the direction of the horizontal seismic body force is noted the results obtained from this paper have been found to compare well with the solutions reported in the literature c 2013 american society of civil engineers

the nonseismic tsunami observed in the bulgarian black sea on 7 may 2007 was it due to a submarine landslide 1 a tsunami like sea disturbance of nonseismic origin was observed on 7 may 2007 on the bulgarian black sea coast the maximum wave amplitude was three meters and the sea oscillations lasted for several hours the anomalous behaviour was seen in many places of the coast of bulgaria and was stronger in the north several accounts of eyewitnesses as well as reports of local port authorities and three tide gauge recordings are available and have been collected and analysed the tsunami could have been produced by a submarine landslide or by atmospheric pressure pulses here we explore the former hypothesis i e the possibility that the tsunami was induced by a landslide that may have occurred on the shelf margin off bulgaria by making use of numerical modelling we find that submarine mass movements taking place within a certain delimited source area off bulgaria may have generated tsunamis compatible with the observations

displacement based seismic design of a shallow strip footing positioned near the edge of a rock slope abstract this paper presents a displacement based dynamic design of shallow strip footings located close to the edge of homogeneous and isotropic rock slopes the analysis is conducted using the generalized tangential technique in which the hoek brown strength is replaced by an optimal tangential mohr coulomb domain within the framework of the kinematic approach of limit analysis theory in order to better understand the influence of these factors including geometrical features rock strength parameters and seismic loading a parametric study is carried out an expression is derived and used to obtain a least upper bound solution for the bearing capacity of a footing on a rock slope considering a kinematically admissible log spiral failure mechanism in addition a similar expression of the horizontal yield seismic coefficient is derived for a given load acting on the foundation the assessment of earthquake induced permanent displacement is performed by a simplified procedure this requires the knowledge of a ground motion parameter that can be evaluated by site specific seismic hazard analyses or ground motion prediction equations and that considers the actual sliding surface the calculated displacement should not be greater than a selected limiting tolerable displacement for the specific case an example is presented illustrating the application of the design procedure for the bridge foundations

calibration of resistance factors for geotechnical seismic design the next edition of the canadian highway bridge design code will contain a table of geotechnical resistance factors to be used for seismic design this paper will estimate the geotechnical resistan

nonlinearity liquefaction and velocity variation of soft soil layers in port island kobe during the hyogo ken nanbu earthquake clear nonlinear behavior is analyzed from the acceleration records of the 1995 hyogo ken nanbu earthquake at port island kobe from four triaxial in struments placed at four different depths the surficial effects during strong ground motions were compared with those during weak motions before and after the main shock we used a spectral ratio technique and a nonlinear inversion for velocity structure to analyze the data from the spectral analysis we observed a large variation of the spectral ratios between the surface and different depths during the strong ground motions and during the liquefied state the spectral ratios after the mainshock i e after the liquefied state are different from those before the mainshock the peak frequencies in the spectral ratios after the mainshock are shifted to lower fre quencies with respect to those in the spectral ratios before the mainshock we in verted the s wave velocities using a genetic algorithm technique to determine the velocity structure before during and after the mainshock the s wave velocity struc ture before and after the mainshock was found to be different specifically the s wave velocity of the second layer 5 m to 16 m depth after the mainshock was 20 lower than before our analysis shows that the liquefied state remains at least 3 hr after the mainshock but no more than 24 hr the rigidity of the soil decreased close to zero when liquefaction happened and later increases gradually following a trend that resembles a consolidation curve the strong influence of nonlinearity during the mainshock yielded a big reduction of the horizontal surface ground motions so that the observed horizontal peak acceleration was only about 25 of the peak acceler ation expected from the linear theory however the nonlinear effects in the vertical peak acceleration were not significant

landslide tsunami vulnerability in the ligurian sea case study of the 1979 october 16 nice international airport submarine landslide and of identified geological mass failures summary the ligurian sea at the france italy boarder of the mediterranean sea has experienced in the past numerous submarine landslides within its very near continental slope the continental shelf being very narrow the most recent occurred on the 1979 october 16 near nice international airport and generated tsunami waves of order 3 m of amplitude in some specific locations more ancient landslides are also easily identified through bathymetric surveys of the seafloor for the 1979 event we propose two distinct tsunamigenic landslides based on identified scars observable on the seafloor the first one corresponds to the volume vol1 that slid at the airport in shallow water while the second one corresponds to the more substantial volume vol2 that has been localized at the slope former studies indicate that only the combination of the two slides may explain the event we complement these studies by asserting that when the two slides are taken separately they already explain a significant although not a total part of the event vol1 explains partly the tsunami observations in the vicinity of the airport while vol2 contributes to explain the ones away from the area in particular at antibes where the highest wave has been observed the modelling effort is then extended to evaluate the tsunamigenesis of selected but representative former landslides having a clear scar signature the vulnerability of the area to landslide triggered tsunami is then proposed to discussion along with possible mechanisms that can be responsible for local wave amplification

reappraisal of vertical motion effects on soil liquefaction introduction ground motion induced by an earthquake is in general characterised by a vector with its components along the vertical and two horizontal directions in current practice and research the effect of vertical ground motion is often disregarded while attention is focused mainly on the horizontal ground motion two primary reasons have been accepted for neglect of the vertical seismic motion first engineering structures are considered to have adequate resistance to dynamic forces induced by the vertical ground motion which is generally much smaller than its horizontal counterparts if the effect of vertical motion is explicitly included in design it is typically assumed that the ratio of vertical to horizontal v h response spectra will not exceed two thirds international code council 1996 second the vertical ground motion is considered to have negligible influence on soil liquefaction because it induces almost purely compressive stresses which cannot cause changes in the effective stress in the subsoil ishihara 1996 however there are repeated observations from recent earthquakes such as those in northridge california in 1994 and kobe japan in 1995 bardet et al 1997 nceer 1997 that the rule of thumb ratio of two thirds is a poor descriptor of vertical ground motions the v h spectral ratios may substantially exceed two thirds in the near field of moderate and large earthquakes and at short periods a typical case comes from the three dimensional borehole array recordings obtained at port island kobe during the 1995 kobe earthquake yang sato 2000 which indicated that the peak vertical acceleration was twice as high as the peak horizontal acceleration at the ground surface fig 1 an integrated study of this case history yang sato 2000 yang et al 2000 has revealed that both the horizontal and the vertical ground motions were closely related to the liquefied soil layers and particularly the condition of partial saturation in the near surface soils played a crucial role in the amplification of vertical motion partial saturation conditions may occur in certain situations as a result of fluctuating groundwater tables associated with natural or man made processes they may also exist in offshore sites or marine sediments thus considerable interest arises in reappraising the effect of vertical ground motion on soil liquefaction and especially in clarifying whether or not this effect is dependent on the saturation condition aimed at this goal analyses have been conducted by means of a verified fully coupled numerical procedure for a model deposit subjected to a variety of combinations of loading and saturation conditions a significant finding of the analyses is that the current understanding that the effect of vertical motion on liquefaction is negligible may not always hold true rather the effect is dependent on the saturation condition this paper presents the main results and the related mechanisms implications of the results for dynamic model testing in the geotechnical laboratory are also addressed briefly

dilatancy induced p waves as evidence for nonlinear soil behavior a much discussed topic in seismology deals with how and under which loading conditions soil shows nonlinear behavior and how this can be verified from seismograms seismologists have been seriously searching for signatures of nonlinear soil response to earthquakes for about two decades a mechanism explaining the dispersion in the p wave spectra due to the interaction between compressional p and shear s waves is presented shear waves in granular materials induce longitudinal dilatancy waves so called waves with approximately double frequency this can be explained with dilatancy and contractancy which is characteristic of granulates under shear deformations the predicted dispersion is observed in laboratory experiments and verified by comparing accelerograms from hard rock and soil stations from the vrancea region romania the arrival time difference between waves and s waves may theoretically be indicative of the thickness of nonsaturated granular layers these results modeled with nonlinear constitutive relations of the rate type show a specific type of nonlinearity in granular sediments also for earthquakes of moderate magnitudes

the landslide tsunami of november 3 1994 skagway harbor alaska we show that the tsunami of november 3 1994 in skagway alaska was generated by an underwater landslide formed during the collapse of a cruise ship wharf undergoing construction at the head of taiya inlet this event occurred at a time of extreme low tide and was not associated with a regional seismic event or incoming oceanic tsunami persistent wave motions with an amplitude of 1 m and a period of 3 min recorded by a tide gauge in skagway harbor following the landslide are linked to the formation of a cross inlet seiche and quarter wave resonance within the harbor the high q factor for the harbor q 20 indicates weak dissipation and strong resonance within the harbor

near source attenuation of peak horizontal acceleration strong motion data recorded within 50 km of the rupture zone were used to study near source attenuation characteristics of horizontal peak ground acceleration for worldwide earthquakes of magnitudes 5 0 to 7 7 the data base consisted of 229 horizontal components of peak acceleration recorded from 27 earthquakes including the 15 october 1979 imperial valley earthquake these data were found to be adequately represented by the functional relationship pga a exp b m r c m d where pga represents the mean of the peak values scaled from the two horizontal components of each recording m is richter magnitude and r is distance from the fault rupture zone peak acceleration was found to be lognormally distributed with a standard error representing a 45 per cent increase in the median estimate the regression analysis statistically confirmed the results of earthquake simulation studies that have predicted peak acceleration to become independent of magnitude and distance in the near field an extensive sensitivity study showed that predictions based on our attenuation relationships are stable with respect to reasonable model and parameter variations an analysis of residuals was used to investigate the behavior of peak acceleration with respect to various earthquake site and recording parameters the more significant findings being 1 a similarity in the level of acceleration recorded on soil or rock 2 larger than average accelerations recorded at sites located on shallow soils or in areas of steep topography 3 larger than average accelerations associated with earthquakes having reverse fault mechanisms and 4 lower than average accelerations recorded in large embedded structures

discussion of subsurface characterization at ground failure sites in adapazari turkey by jonathan d bray rodolfo b sancio turan durgunoglu akin onalp t leslie youd jonathan p stewart raymond b seed onder k cetin ertan bol m b baturay c christensen and t karadayilar a discussion of an article with the aforementioned title published in this journal in july 2004 is presented the discussers reevaluate some of the cases in the original paper to define the causes of the ground failures other than liquefaction the properties for the failure of building sites f c and g are reviewed to consider bearing capacity degradation calculations as a possible cause for the ground failures while there is no current tool or technique to evaluate the liquefaction susceptibility of fine grained soils it may be misleading to claim it as the main cause of damage and destruction

possible atmospheric origin of the 7 may 2007 western black sea shelf tsunami event 1 the paper examines the possibility that tsunami event recorded in the western black sea on 7 may 2007 was triggered by a traveling atmospheric disturbance as meteotsunamis are favored by specific synoptic conditions we inspected available ground and sounding observations european centre for medium range weather forecasts reanalysis fields and satellite based products and compared them to the documented mediterranean meteotsunamis we found an atmospheric disturbance traveling toward 30 nne with amplitude of 2 3 hpa and propagation speed of about 16 m s passing through few tens of kilometers wide pathway over the region affected by the tsunami this disturbance occurred in the lower troposphere but it was capped by instable convective cell that preserved gravity disturbance s coherence over a region at least 150 km long an ocean modeling study showed that such a disturbance is capable of generating large tsunami waves and strong currents over the shallow regions following the observations over the region where maximum sea level oscillations have been documented therefore this event has a potential to be classified as a meteotsunami the first of such kind in the black sea

continental margins as a source of tsunami hazard the 1977 gioia tauro italy landslide tsunami investigated through numerical modeling abstract slides along continental margins represent a considerable source of hazard especially when occurring in shallow water close to a densely populated coast among the known landslide tsunamis affecting harbors or coastal infrastructures the 1977 event that hit the harbor of gioia tauro se tyrrhenian sea italy is one of the less studied according to historical reports 5 m waves hit the western dock provoking relevant damages on port facilities post event bathymetric surveys found a lack of mass of more than 5 million m3 at the head of the gioia tauro canyon that starts just outside the harbor after having considered two possible sliding bodies the respective landslide motion and generated tsunami are calculated here through numerical in house developed numerical codes in order to assess their effects on the coast and validate the hypothesis of a landslide source for the 1977 event tsunami features inside the harbor basin are characterized as well evidencing the importance of assessing the consequence of such small scale events not involving large areas but posing a relevant threat for coastal communities and infrastructures

dynamic response of deep soft soil deposits under multidirectional earthquake loading the analysis of site response to earthquake is of great importance for seismic design of structure although it has long been recognized that the ground is simultaneously subjected to both horizontal and vertical motions during a real earthquake the effect of vertical motion is usually ignored in most site response analyses moreover some studies show that there are significant differences in site responses for saturated and unsaturated soil deposits and site response is influenced by variation of groundwater table therefore these factors should be considerably considered in the dynamic site response analysis based on the results of geological investigation as well as laboratory and field tests conducted in shanghai a deep geotechnical profile with a depth of 280 m is analyzed in this paper by using a verified fully coupled and inelastic finite element procedure a series of numerical analyses is carried out for a deep soft soil profile subjected to multidirectional earthquake loadings parameters of the model in the procedure are calibrated by field and laboratory tests numerical results demonstrate that the behavior of vertical amplification is quite different from the horizontal counterpart furthermore the use of a single horizontal component as seismic input in site response analysis neglecting the other horizontal component and the vertical one may result in considerable underestimation of site response variation of groundwater table brings about a profound effect on both vertical and horizontal motions its ratio the response spectra at ground surface and excess pore water pressure ratio the analysis can capture a more complete and fundamental aspects of ground response for preliminary seismic assessment

the potential failure of monte nuovo at ischia island southern italy numerical assessment of a likely induced tsunami and its effects on a densely inhabited area ischia is the emergent top of a large volcanic complex that rises more than 1 000 m above the sea floor at the north western end of the gulf of naples caldera resurgence in the central part of the island has resulted in the formation of differentially displaced blocks among which mt epomeo 787 m a s l is the most uplifted deformation and slope instability have been recognised as common features induced by a block resurgence mechanism that causes uplift and favours gravitational loading and flank failure the monte nuovo block a topographic high on the north western flank of mt epomeo has recently been interpreted as a block affected by deep seated gravitational slope deformation this block may undergo a catastrophic failure in the case of renewal of magmatic activity this paper investigates the potential failure of the monte nuovo block as a rockslide debris avalanche the consequent tsunami generation and wave propagation and discusses the catastrophic effects of such an event mobilization prone volume has been estimated at about 160 106 m3 and would move from a maximum elevation of 400 m a s l the landslide itself would sweep away a densely populated territory as large as 3 5 km2 the highest waves generated by the tsunami on which this paper is mainly focussed would hit the northern and western shores of ischia however the high coast would prevent inundation and limit devastation to beaches harbours and surrounding areas most of the tsunami energy would head towards the north east hitting the campania coast severe inundation would affect an area of up to 20 km2 around the mouth of the volturno river including the urban area of castel volturno in contrast less energy would travel towards the south and the gulf of naples would be perturbed by long persisting waves of limited damaging potential

interpretation of seismic vertical amplification observed at an array site strong ground motions were recorded at port island kobe by a borehole array during the 1995 hyogo ken nanbu kobe earthquake these records indicate that while the horizontal peak accelerations were reduced as seismic waves traveling from the bottom to the surface motions in the vertical direction were significantly amplified at the surface with peak value of 1 5 to 2 times larger than the horizontal components some studies have discussed local site effects on the horizontal motions whereas the available study on the vertical amplification is limited in this article we present a possible mechanism to explain the observed vertical amplification in detail we consider that the observed large vertical amplification is mainly associated with incomplete saturation of near surface soils which causes substantial amplification of p waves but does not affect the propagation of s waves based on the concept of homogeneous pore fluid and biot s theory of two phase media we discuss the characteristics of p wave velocity poisson s ratio and degree of saturation in shallow soil layers and show evidence of incomplete saturation of near surface soils at the array site we analyze a simple model to theoretically investigate the effects of saturation on vertical motion amplification the results show that the degree of saturation may produce substantial influence on the amplification both amplitude and frequency content using a solid fluid coupled finite element procedure we perform a simulation of the observed vertical motions at the array site by including the effects of saturation the results demonstrate the mechanism of large amplification caused by incomplete saturation of near surface layers the present study indicates that vertical component motions may significantly be affected by pore water saturation of soils suggesting that we may need to carefully examine the condition of saturation in the study of vertical site amplification manuscript received 24 may 1999

ultimate seismic bearing capacities and failure mechanisms for strip footings placed adjacent to slopes assessment of the ultimate bearing capacity of foundations adjacent to slopes is complex as it is highly dependent on the slope geometry and soil properties seismic loading may impact both the cri

historical and pre historical tsunamis in the mediterranean and its connected seas geological signatures generation mechanisms and coastal impacts abstract the origin of tsunamis in the mediterranean region and its connected seas including the marmara sea the black sea and the sw iberian margin in the ne atlantic ocean is reviewed within the geological and seismotectonic settings of the region a variety of historical documentary sources combined with evidence from onshore and offshore geological signatures geomorphological imprints observations from selected coastal archeological sites as well as instrumental records eyewitnesses accounts and pictorial material clearly indicate that tsunami sources both seismic and non seismic e g volcanism landslides can be found in all the seas of the region with a variable tsunamigenic potential local regional and basin wide tsunamis have been documented an improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented from west to east the most important tsunamigenic zones are situated offshore sw iberia in the north algerian margin in the tyrrhenian calabria and messina straits in the western and eastern segments of the hellenic arc in the corinth gulf of central greece in the levantine sea offshore the dead sea transform fault and in the eastern side of the marmara sea important historical examples including destructive tsunamis associated with large earthquakes are presented the mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency 1 96 years is observed in the east mediterranean basin for most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co seismic slip by earthquake triggered submarine landslides or by a combination of both mechanisms in pre historical times submarine volcanic eruptions i e caldera collapse massive pyroclastic flows volcanogenic landslides and large submarine landslides caused important tsunamis although little is known about their source mechanisms we conclude that further investigation of the tsunami generation mechanisms is of primary importance in the mediterranean region inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent well documented aseismic landslide tsunamis e g 1963 corinth gulf 1979 cote d azur 1999 izmit bay 2002 stromboli volcano since the tsunami generation mechanisms are controlled by a variety of factors and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action future interdisciplinary research efforts on past tsunamis are needed

seismic bearing capacity factors for spread foundations the effect of horizontal earthquake body forces on the bearing capacity of foundations has been examined computationally in a rigorous manner by employing the method of stress characteristics the bearing capacity factors n c n q and n y due to the components of soil cohesion ground surcharge pressure and soil unit weight respectively have been plotted as a function of earthquake acceleration coefficient a h for different values of soil friction angle phi the inclusion of earthquake body forces causes a considerable reduction in the bearing capacity factors the bearing capacity factors n c and n q are seen to be approximately of the same magnitude as those reported in the literature on the basis of different solution methods however the obtained values of n y are found to be significantly smaller than the available results the nature of the pressure distribution along the footing base and the geometry of the observed failure patterns vary with the consideration of earthquake body forces

characteristics of vertical and horizontal ground motions recorded during the niigata ken chuetsu japan earthquake of 23 october 2004 abstract the niigata ken chuetsu japan earthquake of 23 october 2004 m w 6 6 was the most significant earthquake that had affected japan since the kobe earthquake of 1995 the dense network of seismographs deployed in this region generated a quality dataset and as such offers a good opportunity to understand events similar to those that can be expected in other parts of the world in this paper characteristics of the free field ground motion recorded during the earthquake are examined the database includes 156 records at 52 sites ranging from rock to stiff soil special attention of this study is placed on the behavior of the recorded vertical ground motion and its relation to the horizontal ground motion the analysis shows that the vertical response spectra generally display low frequency contents at distant sites and high frequency contents at hard sites depending on site distance and site condition the period for peak response in the spectra may vary from 0 05 to 0 15 s the analysis also shows that the vertical to horizontal spectral ratio v h is strongly dependent on spectral frequency site to source distance and site condition the v h ratio can be significantly larger than the rule of thumb value of 2 3 at short periods and tends to exceed 2 3 again at very long periods greater than 5 s

fully coupled inelastic site response analysis for 1986 lotung earthquake two major earthquakes m 6 2 and m 7 with different characteristics took place in the eastern coast of taiwan in 1986 within a 4 month period a test site at lotung was located near the epicenters of the two quakes the site was instrumented with three dimensional 3d surface and downhole accelerometer arrays and pore pressure transducers embedded at depths from 3 to 16 m below the ground surface field investigation of the site including sampling undisturbed soils was carried out before the two events and followed by a laboratory test program aimed at gaining detailed soil properties based on the available information numerical analyses were performed using a fully coupled multidirectional dynamic procedure incorporating a bounding surface hypoplasticity model the calculated responses for the two different events showed equally reasonable agreements with the field records in both 3d acceleration and pore pressure time histories this paper reports the methodology of the analyses and presents

nonlinear site effects on strong ground motion at a reclaimed island recently there has been an increased interest in the study of the nonlinearity in soil response for large strains through in situ earthquake observations in this paper the downhole array acceleration data recorded at a reclaimed island kobe during the 1995 kobe earthquake are used to study nonlinear site effects particular attention is given to the liquefaction induced nonlinear effects on the recorded ground motions by using the spectral ratio and the spectral smoothing technique the characteristics of the ground motions are analyzed it is shown that the peak frequencies in spectral ratios were shifted to lower frequencies when the strongest motions occurred the increase in the predominant period was caused primarily by a strong attenuation of low period waves rather than by amplification of long period motions based on the spectral analyses the nonlinearity occurring in the shallow liquefied layer during the shaking event is identified manifested by a significant reduction of the shear modu

numerical modeling of seismic site effects in a shallow estuarine bay suai bay shantou china abstract this paper presents the results of numerical modeling of seismic site effects in a shallow estuarine bay suai bay shantou china which is meaning for seismic hazard assessment and mitigation of estuarine and coastal structures such as immersed tunnels pipelines caissons and breakwaters the subsurface stratum and soil properties in the study area are obtained from geological and geotechnical surveys large scale 2d finite element refined nonlinear modeling is used to simulate ground motion for near field and far filed input motions with different design earthquake levels the results show that for the study area 1 the spatial distribution of pga amplification factor presents obvious vertical and horizontal variations and is strongly affected by the overall geometry of interfaces of different materials 2 the attenuation in soft sediments have significant influences on surface ground motion which leads to a deamplification of the acceleration amplitude a prolongation of the significant duration and a filtration of the high frequency spectral content 3 the pga alone cannot be regarded as an adequate parameter to quantify nonlinear site effects while the energy content expressed by arias intensity is more closely related to transfer functions patterns 4 the seismic intensity at surface is greater than the intensity of input motion during weak motions while the seismic intensity at surface is smaller than the intensity of input motion during strong motions suggesting that isolation effects may be expected in the areas having thick soft soils with a low plasticity index during strong motions

seismic bearing capacity of foundations on slopes the effect of pseudo static horizontal earthquake body forces on the bearing capacity of foundations on sloping ground has been assessed using the method of stress characteristics two failure mechanisms were considered based on the extension of the characteristics from the ground surface towards the footing base from either one side or both sides the magnitude of n gamma based on the both sides failure mechanism for smaller values of earthquake acceleration coefficient alpha h has been found to be significantly smaller than that obtained using the single side mechanism however in the presence of alpha h the both sides mechanism becomes kinematically inadmissible in many cases for higher values of phi only the single side mechanism was found statically admissible for computing the bearing capacity factors n c and n q on sloping ground all the bearing capacity factors reduce considerably with increase in ah for various ground inclinations

large deepwater slope failures implications for landslide generated tsunamis deepwater landslides are often underestimated as potential tsunami triggers the north gorringe avalanche nga is a large 80 km3 and 35 km runout newly discovered and deepwater 2900 m to 5100 m depth mass failure located at the northern fl ank of gorringe bank on the southwest iberian margin steep slopes and pervasive fracturing are suggested as the main preconditioning factors for the nga while an earthquake is the most likely trigger mechanism near fi eld tsunami simulations show that a mass failure similar to the nga could generate a wave 15 m high that would hit the south portuguese coasts in 30 min this suggests that deepwater landslides require more attention in geo hazard assessment models of southern europe as well as at a global scale in seismically active margins

a parametric study of tsunamis generated by submarine slides in the ormen lange storegga area off western norway tsunami generation by submarine slides have been a major concern in the risk assessment for the ormen lange gas field off western norway tsunamis are analysed with a numerical model supplemented by an analytical one both models show how slide extensions and slide dynamics influence the tsunamigenic potential for a large region several combinations of slide parameters were tested and the product of initial acceleration and the volume of the slide gave the best correlation with the maximum surface elevation for the near coastal domain

the landslide generated tsunami of november 3 1994 in skagway harbor alaska a case study we examine the origin and behavior of the catastrophic tsunami that impacted skagway harbor at the head of taiya inlet alaska on november 3 1994 geomorphologic and tide gauge data combined with numerical simulation of the event reveal that the tsunami was generated by an underwater landslide formed during the collapse of a cruise ship dock undergoing construction use of a fine grid model for skagway harbor and a coarse grid model for taiya inlet enables us to explain many of the eyewitness accounts and to reproduce the dominant oscillations in the tide gauge record including the persistent 1 h 3 min oscillation in skagway harbor the occurrence of the landslide is linked to critical overloading of the slope materials at a time of extreme low tide

passive pressure coefficients critical failure surface and its kinematic admissibility using a combination of a logarithmic spiral and a straight line as a failure surface comprehensive charts have been developed to determine the passive earth pressure coefficients and the positions of the critical failure surface for positive as well as negative wall friction angles translational movement of the wall has been examined in detail considering the soil as either an associated flow dilatant material or a non dilatant material to determine the kinematic admissibility of the limit equilibrium solutions

site effect evaluation using spectral ratios with only one station the spectral ratio technique is a common useful way to estimate empirical transfer function to evaluate site effects in regions of moderate to high seismicity the purpose of this paper is to show that it is possible to estimate empirical transfer function using spectral ratios between horizontal and vertical components of motion without a reference station the technique originally proposed by nakamura to analyze rayleigh waves in the microtremor records is presented briefly and it is discussed why it may be applicable to study the intense s wave part in earthquake records results are presented for three different cities in mexico oaxaca oax acapulco gro and mexico city these cities are very different by their geological and tectonic contexts and also by the very different epicentral distances to the main seismogenic zones affecting each city each time we compare the results of nakamura s technique with standard spectral ratios in all three cases the results are very encouraging we conclude that if site effects are caused by simple geology a first estimate of dominant period and local amplification level can be obtained using records of only one station

damage to sewerage systems during the 2004 earthquake in niigata ken chuetsu japan the 2004 earthquake in niigata ken chuetsu japan caused widespread damage to sewer pipelines due to uplift behaviors caused by ground settlement after liquefaction sewer pipelines which are important lifelines suffer damage when sewerage systems cease to operate over a long period of time manholes ejected from the ground s surface can disrupt traffic to study the failure mechanism after the earthquake the nagaoka city government conducted an open cut survey of the damaged sewerage systems the main features of the collected data included the locations of damaged sections and the inclination of the sewer pipes before and after the earthquake in the present study the cause of damage to the sewerage systems was investigated using the datasets and the standard penetration test spt borehole logs the relationship between the sewer pipeline damage and the geological settings in the affected area reveals that the groundwater depth and the geotechnical properties of the original subsoils acted as the key parameters influencing the manhole uplift behavior also the uplift mechanism was investigated through centrifuge modeling tests and these findings agree well with the test results obtained in this study

potential tsunamigenic submarine landslides in active margins abstract a review of modern historical and submarine landslides from the geological record shows that landslides in active continental margins can generate tsunamis the tsunamis may damage coastal and seabed infrastructure and so represent an important element of marine geohazards research due to their potentially significant impacts on society the primary trigger mechanism of tsunamis in this type of setting was thought to be earthquake activity however there are also a number of alternative hypotheses regarding the likely initiation mechanism including the generation of submarine landslides in this paper we briefly review the geological features and trigger mechanisms of tsunamigenic submarine landslides on active margins large tsunamigenic submarine landslides appear to occur mostly on margins characterized by non accretion these observations have implications for tsunami warning systems as the japanese system does not consider the scenario of tsunami excitation by submarine landslides

foundation models in seismic areas four case studies near the city of granada spain abstract this paper presents four case studies of the geotechnical characteristics of foundation design under seismic conditions in towns located in the province of granada spain much of this province is affected by seismic activity caused by active faults in the betic cordillera the alboran sea the atlantic ocean and the area around the northern border of africa from morocco to algeria although seismic activity in the region is moderate with peak accelerations of 2 4 m s 2 for a return period of 475 years it is the region with the highest seismic risk in the iberian peninsula the four study areas include the towns of atarfe albolote fuente vaqueros churriana de la vega and the district of la chana the nw sector of the city of granada churriana de la vega has a very homogeneous soil profile with a coarse granulometry high relative density high bearing capacity high field penetration test values and a deep water table in contrast the other three areas have a seasonally shallow water table and extremely variable soil profiles in terms of bearing capacity they are characterized by predominantly fine alluvial soils of low relative density and with low field penetration test values they are thus susceptible to seismic effects such as liquefaction and densification based on geotechnical reports dynamic penetration tests and direct shear and consolidation tests on disturbed samples we first defined the basic mechanical properties of the soil under static conditions and determined the features related to bearing capacity and foundation design the next step was to analyze the corresponding dynamic geotechnical parameters by using various empirical correlations between static and dynamic parameters for this purpose our research study took into account the definitions and criteria regarding bearing capacity under seismic conditions regulated by the spanish nsc 02 and european eurocode 8 technical codes the results obtained led us to propose new foundation types which would be capable of withstanding potential seismic action these improved foundations have a better load distribution and higher stiffness thanks to strip footing reinforced concrete plates and the occasional use of deep piling the dynamic actions of the terrain and the associated settlement effects due to soil liquefaction or densification showed that the areas most in need of deep foundations were located around albolote as a result a deeper foundation is necessary such as the type found in fuente vaqueros where geotechnical conditions are even more unfavorable

seismic bearing capacity of soils this paper derives the seismic bearing capacity factors for a c phi soil within the framework of the mohr coulomb theory horizontal and vertical accelerations and the effects of a inertia forces of the soil both below and above the footing and b the applied loads are all taken into consideration the method is used to derive the ultimate seismic bearing capacity for a square footing 2 5m wide founded 1 0m below a homogeneous soil with c soil cohesion parameter 7 kpa phi 25 degrees and a unit weight of 18 kn per cubic metre the results indicate that the horizontal accelerations as well as soil cohesion and vertical accelerations affect the bearing capacity coefficients considerably

factors affecting site response to multi directional earthquake loading abstract this paper presents an investigation into various factors that may affect the ground response to multi directional earthquake loading focusing mainly on the behavior of vertical ground motion and its relation with the horizontal counterpart the factors investigated herein include the intensity of input motion and the associated soil nonlinearity the location of input motion rock outcrop versus bedrock the variation of water table and the damping property of soil influence of these factors is studied on the characteristics of site amplification in both vertical and horizontal directions the response spectra of vertical and horizontal ground surface motions the spectral ratio between the two components v h at the ground surface and the distributions of stresses and strains in the ground one of the main results is that varying water table can bring about a significant impact on vertical motion and the relationship between vertical and horizontal motions the surface response spectral ratio v h can largely exceed the rule of thumb value of 2 3 at low periods with lowering the water table but does not appear to be substantially affected at long periods

revealing the source of the 27 august 1810 loreto baja california tsunami from historical evidence and numerical modelling historical documents revealed that on 27 august 1810 an earthquake affected the loreto town and the surrounding region along 200 km of the coast of baja california mexico and damage was considerable due to strong ground motions however the 1810 loreto earthquake unlike other earthquakes of the nineteenth and twentieth centuries produced an extensive tsunami flooding on the eastern coast of baja california from loreto to la paz we report here the historical account of this event and analyse the source of the related tsunami based on the historical record and the tectonic setting we infer that this earthquake was produced along a transform fault right lateral strike slip fault farallon fault on the baja california gulf however the associated tsunami was disproportionally large if compared with the earthquake intensity ix and approximate magnitude 7 4 mw fault style and the relatively late tsunami arrival i e an hour after the earthquake suggesting that a submarine landslide triggered by this earthquake was the suspect source for the loreto tsunami we present here historical data and a numerical model of the loreto 1810 tsunami to elucidate the source using both the 1810 earthquake and a submarine landslide and confirm that a submarine landslide is most likely the tsunami triggering mechanism that followed the 1810 earthquake

frequency and triggering of small scale submarine landslides on decadal timescales analysis of 4d bathymetric data from the continental slope offshore nice france time series bathymetric data acquired from 1967 to 2011 are used to evaluate the morphological evolution of the continental shelf and upper continental slope off the city of nice se france ligurian sea mapping in water depths of 0 300 m was undertaken to identify the changing morphology of landslide scars and their erosive chutes quantitative digital terrain model dtm comparisons reveal areas of erosion and deposition over intervals of 5 8 years sediment remobilization events on the upper slope above depths of 200 m are frequent and significant landslide scars with volumes 25 000 m3 can occur with frequencies of 200 m periods of quiescence 1980 1990 and 2006 2011 are seen to alternate with periods when rapid retrogressive failure increase sediment volumes eroded from the upper slope shelf transition by an order of magnitude 1999 2006 temporal variations in landslide activity were correlated to several potential triggering factors that individually would not induce failures including earthquake activity rapid deposition of fine grained sediments on a steep slope and rainfall leading to fresh groundwater circulation below the shelf this 4d bathymetric study suggests that over the last 50 years the most important factor triggering landslides offshore nice is overpressure due to freshwater outflows

three dimensional simulation of the near fault ground motion for the 1995 hyogo ken nanbu kobe japan earthquake abstract the 17 january 1995 hyogo ken nanbu earthquake is a typical example showing that the ground motions along basin edge faults can be very destructive in this study we simulate the near fault ground motion from this earthquake based on a kinematic fault model and a simplified 3d velocity structure of the kobe area the kinematic earthquake rupture and the wave propagation are modeled using a 3d finite difference method fdm our simulation identifies the basin edge effect as an important factor that influenced the ground motion amplification pattern in the kobe area we found that the coupling of the source directivity and basin edge effects causes impulsive ground motions with extremely high amplitude at periods greater than 1 sec and in a narrow zone offset less than 1 km from the basin edge the combination of these effects acted to create a fairly continuous band of amplification that extends about 30 km in an elongated zone parallel to the basin edge boundary in some areas localized site effects might have been as important as the abovementioned effects but they cannot explain the continuity of the extended east west zone of damage

the landslides and tsunamis of the 30th of december 2002 in stromboli analysed through numerical simulations on the 30th of december 2002 two tsunamis were generated only 7 min apart in stromboli southern tyrrhenian sea italy they represented the peak of a volcanic crisis that started 2 days before with a large emission of lava flows from a lateral vent that opened some hundreds of meters below the summit craters both tsunamis were produced by landslides that detached from the sciara del fuoco this is a morphological scar and is the result of the last collapse of the northwestern flank of the volcanic edifice that occurred less than 5 ka b p the first tsunami was due to a submarine mass movement that started very close to the coastline and that involved about 20 106 m3 of material the second tsunami was engendered by a subaerial landslide that detached at about 500 m above sea level and that involved a volume estimated at 4 9 106 m3 the latter landslide can be seen as the retrogressive continuation of the first failure the tsunamis were not perceived as distinct events by most people they attacked all the coasts of stromboli within a few minutes and arrived at the neighbouring island of panarea 20 km ssw of stromboli in less than 5 min the tsunamis caused severe damage at stromboli

subaqueous landslides at the distal basin of lago nahuel huapi argentina towards a tsunami hazard evaluation in northern patagonian lakes abstract the may 22nd 1960 valdivia earthquake chile mw 9 5 triggered a series of subaqueous mass wasting processes debris flows and slides in lago nahuel huapi argentina generating a tsunami like wave that hit the coasts of san carlos de bariloche aiming to provide a first preliminary insight into tsunami hazards for the lakeshore communities in this paper we identify and characterize the subaqueous landslides at the populated distal basin of the lake swath bathymetric and seismic profiling surveys were carried out and high resolution digital elevation models were derived from these data to perform a landslide inventory map a series of morphometrical parameters including the landslide area the volume of displaced materials and the run out distance among others were estimated upon selected events the results indicated that landslide activity at the distal basin of lago nahuel huapi has been concentrated in the vicinity of bariloche massive landslide triggered by the 1960 earthquake and within steep delta fronts where the slope failures typically initiate at shallow waters 9 11 m depth the sliding mass frequently travels basinward along a great distance 1000 m at the delta fronts the volume of material removed by landslides can reach 40 10 4 m 3 leaving scar areas of up to 13 m thick the periodic occurrence of rotational translational mass movements initiating at the upper edge of the delta fronts with vertical displacements of the mobilized materials reaching 200 m probably represents a potential tsunami hazard for the nearby populated coasts

numerical modelling of a landslide generated tsunami the 1979 nice event on the 16th of october 1979 a part of the nice new harbour extension close to the nice international airport french riviera slumped into the mediterranean sea during landfilling operations a submarine slide with initial volume close to seashore of about 10 millions m3 which could have evolved later into an avalanche was followed by a small tsunami noticed by several witnesses in the baie des anges the maximum tsunami effects were observed 10 km from the slide location near antibes city which was inundated previous analyses used rough approximate methods and produced models which did not conveniently fit data in this paper both the slide and the generated water waves are numerically simulated on the basis of the shallow water approximation the landslide is assimilated to a heavy newtonian homogeneous fluid downslope under gravity water waves are generated by sea bottom displacements induced by the landslide taking into account a very accurate multibeam bathymetric map the nice slide of 10 millions m3 is simulated by this model the numerical results are generally consistent with the observed hydraulic local effects in front of the nice airport however they are not in agreement in the far field a larger and deeper landslide 2 km off nice airport is tested to quantitatively study the effects of the landslide volume on water waves generation

analysis of earthquake recordings obtained from the seafloor earthquake measurement system sems instruments deployed off the coast of southern california for more than 20 years a program has been underway to obtain records of earthquake shaking on the seafloor at sites offshore of southern california near oil platforms the primary goal of the program is to obtain data that can help deter mine if ground motions at offshore sites are significantly different than those at onshore sites if so caution may be necessary in using onshore motions as the basis for the seismic design of oil platforms we analyze data from eight earthquakes recorded at six offshore sites these are the most important data recorded on these stations to date seven of the earthquakes were recorded at only one offshore station the eighth event was recorded at two sites the earthquakes range in magnitude from 4 7 to 6 1 because of the scarcity of multiple recordings from any one event most of the analysis is based on the ratio of spectra from vertical and horizontal compo nents of motion the results clearly show that the offshore motions have very low vertical motions compared to those from an average onshore site particularly at short periods theoretical calculations find that the water layer has little effect on the horizontal components of motion but that it produces a strong spectral null on the vertical component at the resonant frequency of p waves in the water layer the vertical to horizontal ratios for a few selected onshore sites underlain by relatively low shear wave velocities are similar to the ratios from offshore sites for frequencies less than about one half the water layer p wave resonant frequency suggesting that the shear wave velocities beneath a site are more important than the water layer in determining the character of the ground motions at lower frequencies

potential mass movements on the palinuro volcanic chain southern tyrrhenian sea italy and consequent tsunami generation abstract the palinuro volcanic chain pvc is located about 80 km offshore the campania region italy in the southern sector of the tyrrhenian sea the chain consists of 15 volcanic edifices aligned in an e w direction with two distinct major seamounts palinuro and glabro they cover a 90 km long and 20 km wide area with a present day volume of 2700 km3 palinuro volcanism emplaced between 0 8 and 0 3 ma although shallow seismicity and hydrothermalism indicate an ongoing volcanic activity a geomorphological analysis of the volcanic chain and data from a multichannel seismic profile reveal large volumes of buried chaotic material suggesting gravity mass sliding from the volcano flanks and slide scars a stability analysis of the palinuro flanks has been carried out to determine the sectors potentially prone to sliding in case of shallow volcanic earthquakes landslides are simulated by adopting a scenario based approach tsunamis induced by these mass movements and their propagation across the tyrrhenian sea are modeled results suggest that shallow earthquakes m 4 6 4 8 are able to destabilize the flanks of the volcanic chain generating slope failures sliding volumes in the order of 1 5 km3 and 2 4 km3 may induce waves as high as 1 5 and 6 m respectively along the peri tyrrhenian coast our results underline the need for further investigations on the stability of the submarine volcanoes of the tyrrhenian basin these volcanoes are still poorly known although their instability could trigger large tsunamis along the southern italy coastal sectors our recommendation is that multiparamertic monitoring networks on pvc and periodic oceanic cruises should be put into action and further that a systematic evaluation of the tsunami hazard related to possible sliding phenomena on the flanks of the tyrrhenian seamounts should be performed

static and seismic passive earth pressure coefficients on rigid retaining structures the passive earth pressure problem is investigated by means of the kinematical method of the limit analysis theory a translational kinematically admissible failure mechanism composed of a sequence

liquefaction and flow failure during earthquakes two aspects of seismically induced liquefaction are discussed which are of vital engineering significance the triggering condition and the consequences of liquefaction the triggering condition is examined with respect to liquefaction analysis note being taken of the onset condition which is governed by cyclic strength consequences of liquefaction are discussed with respect to post seismic stability analysis in which the residual strength plays a major role procedures used for liquefaction analysis based on the results of in situ sounding tests are introduced and the applicability of this method for estimating associated ground settlements is discussed the evaluation of residual strength requires a better understanding of undrained sand behaviour results of extensive laboratory rests on japanese standard sand are examined and new index parameters are proposed to quantify undrained sand behaviour better the results of laboratory tests on silty sands are examined in the same way ah the results are