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Earthquake-induced soil liquefaction can cause enormous life and economic losses. The joint distribution of the peak ground surface acceleration ( a max ) and the moment magnitude of an earthquake ( M w ) is crucial to the estimation of soil liquefaction-related hazards. In this paper, a new method is suggested to estimate the joint distribution of a max and M w . Compared with the existing method, the suggested method is easier to implement, and depends on fewer assumptions. The derived joint distribution is then used to assess the damage state of a building caused by soil liquefaction during a given exposure time. The method is illustrated with an example in which a reinforced concrete frame building is assumed to be at different locations and is subjected to different exposure time. It is found that, as the exposure time increases, the chance of higher degree of damage also increases. When the exposure time is the same, the damage state of the building may also be different when it is at different locations. The method suggested in this paper can be used to quantify the effect of ground condition as well as the seismic effects at a site on the damage state of a building, thus providing a more transparent understanding of the risk associated with the soil liquefaction hazard on structural damage. [ABSTRACT FROM AUTHOR]

In recent years, many have mapped the liquefaction potential index (LPI) to describe the liquefaction hazard at regional scale. Several investigators have calibrated the LPI to field observations of liquefaction-induced ground failure after a number of major earthquakes; the significance of LPI values and their correlation with the severity of liquefaction-induced ground failure can vary greatly depending on the calibration. In this study, the LPI was computed at more than 1200 cone penetration test soundings across the Christchurch area, New Zealand, using peak ground accelerations from the 2011 Christchurch Earthquake. Based on detailed field observations of liquefaction-induced ground failure after the earthquake, it was shown that the LPI has potential for discriminating between areas with no liquefaction-induced ground failure hazard and areas that may experience liquefaction-induced ground oscillations and settlement; however, the LPI performed poorly at sites where severe ground failures occurred, especially at sites that experienced lateral spreading. As many researchers have found a positive correlation between lateral spreading and the proximity and depth of a nearby free-face (i.e., a steep topographic depression, river channel, etc.), a new LPI framework was proposed that includes a parameter named the free-face ratio ( FFR ). FFR was shown to have a significant correlation with field observations of lateral spreading in Christchurch. It was shown that by incorporating FFR into the LPI framework, modified LPI values are positively correlated with the severity of field observations of liquefaction-induced ground failure in Christchurch. It was also shown that maps can be produced based on LPI and FFR , and such maps rarely underpredict the liquefaction-induced ground failure hazard, unlike maps based on the unmodified LPI. [ABSTRACT FROM AUTHOR]

The seismic hazard studies for Egypt have been initiated a long time ago aiming to predict the ground motion parameters at different geographical scales; their review process had been routinely performed due to the increase of available instrumental observations rather than from methodological advances. For the comprehensive understanding of the development of seismic hazard assessment (SHA) studies in Egypt, we properly collect and test the existing SHA maps, computed at different geographic scales, against the available observations, data quality, physical assumptions and adopted methodology. Most of these SHA studies are probabilistic and the mapped ground motion acceleration values have been often largely exceeded by the observed values due to earthquakes occurred after their publication. For each study, we discuss and evaluate the input data, methodology and the results obtained in order to understand the reasons behind the bad performance of the available seismic hazard maps and to avoid such shortcomings in future seismic hazard assessment. Finally, we formulate suggestions that could be considered before new seismic hazard maps are released and then adopted, for the real benefit of society. [ABSTRACT FROM AUTHOR]

The landslides induced by the Mid-Niigata Offshore earthquake in 2007 (M JMA 6.8) occurred mostly along the shore of the Japan Sea. This study focused on the landslides that occurred near the Hijirigahana Cape, Yoneyama Town in the Niigata Prefecture. The study area is located in the western region of the central Niigata Prefecture, along the Japan Sea. The geology of the landslide area is dominated by late Miocene sandstone-rich member of alternating beds of sandstone and siltstone. These strata gently dip to the north at approximately 25° to 30° and form cataclinal and orthoclinal slopes on the north- and west-facing slopes, respectively. The central Niigata region is one of the most landslide-prone areas in Japan. The study area is located approximately 30 km from the epicenter of the earthquake with an estimated intensity of 6 lower in the JMA (Japan Meteorological Agency) scale. A group of landslides occurred in the study area. The area contains the most concentrated set of landslides from this earthquake, even though it is located far from the epicenter. Most of the landslides occurred on north-facing slopes, but two occurred on west-facing slopes. The landslides on the north-facing slopes are characterized as translational slides. The largest rock slide in the study area, Unit D (width 100 m, length 230 m), slipped along the bedding plane of the strata. Observations from slickenlines from the slip surface and outcrop in the upper portion of Unit D suggest that before this earthquake, landslides frequently occurred on the north-facing slopes and were controlled by the bedding plane. With the exception of the largest one, other landslides on north-facing slopes were mostly debris slides, indicating that sediments from older landslides exist. The second largest landslide occurred on a west-facing orthoclinal slope. A rotational rock slide, Unit A, was 80 m wide and 100 m long. During the excavation after the landslide, a high angle fault with a SW dip was identified behind the crushed zone. Based on field observation, the fault was considered to be a non-tectonic fault and created by gravitational movement. During the excavation, the crushed zone was identified on the cutting wall of the slope. These results revealed that the relatively larger rotational rock slides occurred because of the existence of the crushed zone due to older events that caused the slippage along a non-tectonic fault. [ABSTRACT FROM AUTHOR]

Abstract: Fragility curves can be developed using analytical or empirical methods. When the actual building damage records and the associated ground motion data are available, empirical methods are often adopted. Traditionally, district-based records of building damage are analyzed for developing such fragility curves. In this paper, a new procedure based on the concept of “isointensity-isoexposure” is developed. The new procedure is demonstrated through a case study of the building damage records collected from the 1999 Chi-Chi, Taiwan earthquake. The results show that the fragility curves developed with the proposed procedure are more in-line with observations than with the traditional district-based procedure. The developed fragility model may be used for earthquake loss estimation and future emergency planning in the study area. The limitations of the proposed approach include: (1) the developed fragility curves are area-specific and may not be readily applicable to other regions, and (2) ground motion intensity data may not be available at every location in an area of interest. [Copyright &y& Elsevier]

Abstract: Permanent sliding displacement represents a common damage parameter for evaluating the seismic stability of slopes. Recently developed empirical models for the sliding displacement of shallow (rigid) sliding masses have demonstrated that including multiple ground motion parameters in the predictive model (e.g., peak ground acceleration and peak ground velocity) improves the displacement prediction and reduces it uncertainty. A unified framework is developed that extends these empirical displacement models for application to flexible sliding masses, where the dynamic response of the sliding mass is important. This framework includes predicting the seismic loading for the sliding mass in terms of the maximum seismic coefficient (kmax) and the maximum velocity of the seismic coefficient-time history (k–velmax). The predictive models are a function of the peak ground acceleration (PGA), peak ground velocity (PGV), the natural period of the sliding mass (Ts), and the mean period of the earthquake motion (Tm). The empirical predictive models for sliding displacement utilize kmax and k–velmax in lieu PGA and PGV, and include a term related to the natural period of the sliding mass. This unified framework provides a consistent approach for predicting the sliding displacement of rigid (Ts =0) and flexible (Ts >0) slopes. [Copyright &y& Elsevier]

Abstract: The influence of site effects on landslide triggering during earthquakes has been inferred in several studies, but its evaluation is made difficult by the complexity of factors controlling the dynamic response of potentially unstable slopes and also by the lack of local ground motion instrumental observations. This work explores this problem and reports new findings based on an ongoing long term accelerometric monitoring conducted on a landslide-prone test area in the Apennine Mountains, Italy, where the presence of site effects enhancing seismic susceptibility of local slopes has been invoked on the basis of historic accounts of landsliding triggered at large epicentral distance. The recordings relative to low-to-moderate magnitude earthquakes showed significant amplifications affecting hillslope portions covered by thick (>5m) colluvia and pronounced amplification maxima oriented along the local maximum slope direction on a recent deep-seated landslide. While the amplifications seem most likely linked to high impedance contrast between surface materials and underlying substratum, the causes of directivity are less clear. The case of the monitored test site together with evidence of site response directivity identified on other hillslopes, suggest that the directivity phenomena can result from a combination of topographic, lithological and structural factors that act together to re-distribute shaking energy, focusing it on site-specific directions. Thus, it is difficult to single out the critical factors controlling such phenomena and no general criterion for the identification of sites affected by directivity is proposed here. Nevertheless, the presence and orientation of site response directivity can be revealed through reconnaissance techniques by using recordings of seismic weak motion and/or ambient microtremors, and calculating azimuthal variation of shaking energy and horizontal-to-vertical ground motion spectral ratios. A comparison with the recordings obtained during the recent MW =6.3 earthquake that hit the Abruzzo region in April 2009 demonstrated that analysis relying on data from low energy events can furnish valid indications for slope behaviour also under stronger shaking, provided the data are well differentiated in terms of distance, azimuth and source characteristics. Furthermore, the comparative analysis of the Abruzzo earthquake recordings at a landslide and reference sites showed that directivity properties of strong shaking had been correctly anticipated using earlier weak motion observations. However, under the complex slope conditions the identification of resonance frequencies from horizontal-to-vertical spectral ratios estimated from weak-motion accelerometric recordings does not seem reliable, and better results have been obtained by velocimetric microtremor recordings. [Copyright &y& Elsevier]

Abstract: In this article we examine how variability in driving and resisting force parameters together translate into uncertainty in seismic slope deformation predictions. Predictive uncertainty of the Newmark rigid-block and Makdisi–Seed decoupled deformation-based methods was evaluated by performing a series of probabilistic Monte Carlo simulations for two idealized slope models. Results from these analyses demonstrate that the highly non-linear relationship between acceleration ratio and displacement associated with the deformation models dictates the way in which parametric variability is propagated through the analysis and can lead to varying degrees of uncertainty in the deformation predictions. Based on this observation, three zones along the displacement-acceleration ratio relationship were identified according to their relative degree of non-linearity and correlated with their relative influence on predictive uncertainty; these are: (i) highly uncertain, (ii) moderately uncertain and (iii) low uncertainty. Using this framework, the widely held notion of a generic “order-of-magnitude” estimate for deformation predictions is a misnomer. Based on this, it is recommended that realistic levels of parametric variability be incorporated in the seismic slope deformation analysis to establish the operating conditions of the slope system. Slopes identified as highly uncertain or moderately uncertain require a more robust probabilistic analyses to meaningfully interpret poorly constrained deformation predictions. [Copyright &y& Elsevier]

Abstract: Earthquake induced dip-slope sliding or rock-block sliding is usually analyzed using friction angles or friction coefficients measured at the sliding interface. A tilt test is a convenient test for measuring the required friction angle. However, a tilt test is a test under static conditions, and the applicability of measured friction parameters to analyze slopes under dynamic excitation requires further discussion. This study conducts a static tilt test and a dynamic shaking table test to simulate block sliding with base excitation, compares differences in measured sliding thresholds, and discusses the cause of these differences. Tests on three different materials (aluminum, sandstone, and synthetic sandstone) show that friction coefficients measured by tilt tests are always larger than the ones derived by shaking table tests. Moreover, high frequency tests yield larger friction coefficients, suggesting the sliding threshold is non-constant under excitation. In addition, tests with varying normal stresses on the sliding block show that with increasing contact stresses, sliding thresholds decrease, implying that sliding threshold varies with normal stress. Instantaneous friction coefficients, μ i (t), during sliding are also studied in this work. It has been found that frictional behavior of synthetic sandstone deviates from the idealized Coulomb friction model. The instantaneous friction coefficient varies with relative displacement and relative velocity during sliding. Finally, reasons for differences between a static tilt test and a dynamic shaking table test are discussed. This study preliminarily identifies the limitations of the tilt test when applied to dynamic problems, and concludes that realistic sliding thresholds can only be obtained using dynamic tests such as shaking table tests. [Copyright &y& Elsevier]

Abstract: During the twentieth century, several methods to assess the stability of slopes during earthquakes were developed. Pseudostatic analysis was the earliest method; it involved simply adding a permanent body force representing the earthquake shaking to a static limit-equilibrium analysis. Stress-deformation analysis, a later development, involved much more complex modeling of slopes using a mesh in which the internal stresses and strains within elements are computed based on the applied external loads, including gravity and seismic loads. Stress-deformation analysis provided the most realistic model of slope behavior, but it is very complex and requires a high density of high-quality soil-property data as well as an accurate model of soil behavior. In 1965, Newmark developed a method that effectively bridges the gap between these two types of analysis. His sliding-block model is easy to apply and provides a useful index of co-seismic slope performance. Subsequent modifications to sliding-block analysis have made it applicable to a wider range of landslide types. Sliding-block analysis provides perhaps the greatest utility of all the types of analysis. It is far easier to apply than stress-deformation analysis, and it yields much more useful information than does pseudostatic analysis. [Copyright &y& Elsevier]

Abstract: Although, thanks to the new developments in investigation techniques, modeling, and data analyses, much progress has been made in our understanding of collateral seismic hazards, important new lessons are still being learned from historic and recent earthquakes. By referring to the accompanying papers included in this Special Issue and other recent literature, we present an overview of current issues and future challenges of research on earthquake, triggered landsliding. We also offer some recommendations for future research priorities, as a proposed starting point for the next generation of research on earthquake-induced slope failures. These include i) the compilation of many more complete seismic landslide inventories with adequate contextual information, as well as of retrospective inventories; ii) the improvement of regional-scale assessments of seismic landslide susceptibility and hazard; iii) the development of new methods for regional scale analysis of hazards from large catastrophic landslides; and iv) the long-term monitoring of representative test slopes instrumented with an array of accelerometer stations. [Copyright &y& Elsevier]

Abstract: A method for total risk analysis of embankment dams under earthquake conditions is discussed and applied to the selected embankment dams, i.e., Chang, Tapar, Rudramata, and Kaswati located in the Kachchh region of Gujarat, India, to obtain the seismic hazard rating of the dam site and the risk rating of the structures. Based on the results of the total risk analysis of the dams, coupled non-linear dynamic numerical analyses of the dam sections are performed using acceleration–time history record of the Bhuj (India) earthquake as well as five other major earthquakes recorded worldwide. The objective of doing so is to perform the numerical analysis of the dams for the range of amplitude, frequency content and time duration of input motions. The deformations calculated from the numerical analyses are also compared with other approaches available in literature, viz, Makdisi and Seed (1978) approach, Jansen''s approach (1990), Swaisgood''s method (1995), Bureau''s method (1997), Singh et al. approach (2007), and Saygili and Rathje approach (2008) and the results are utilized to foresee the stability of dams in future earthquake scenario. [Copyright &y& Elsevier]

Abstract: A new comprehensive areal model of earthquake-induced landslides (CAMEL) has been developed to assist in planning decisions related to disaster risk reduction. CAMEL provides an integrated framework for modeling all types of earthquake-induced landslides using fuzzy logic systems and geographic information systems. CAMEL is designed to facilitate quantitative and qualitative representation of terrain conditions and knowledge about these conditions on the likely areal concentration of each landslide type. CAMEL has been empirically evaluated with respect to disrupted landslides (Category I) using a case study of the 1989 M =6.9 Loma Prieta, CA earthquake. In this case, CAMEL performs best in comparison to disrupted slides and falls in soil. For disrupted rock fall and slides, CAMEL''s performance was slightly poorer. The model predicted a low occurrence of rock avalanches, when none in fact occurred. A similar comparison with the Loma Prieta case study was also conducted using a simplified Newmark displacement model. The area under the curve method of evaluation was used in order to draw comparisons between both models, revealing improved performance with CAMEL. CAMEL should not however be viewed as a strict alternative to Newmark displacement models. CAMEL can be used to integrate Newmark displacements with other, previously incompatible, types of knowledge. [Copyright &y& Elsevier]

• Slope stability is a critical consideration for superstructures and infrastructures. • Estimation of the earthquake-triggered landslide displacement is one of the most important topics of slope engineering. • Newmark sliding block model is a widely used method for predicting earthquake-induced ground displacement. • A new useful and more appropriate regression equation has been obtained to estimate the Newmark displacement. Landslides are one of the most important results of earthquakes. Estimation of the earthquake-triggered landslide displacement is a major topic for engineering because the amount of ground displacement is significant for seismic hazard assessment. Newmark sliding block model is a method commonly used to estimate earthquake-induced ground displacements. Based on this method some regression analyses have been carried out and different equations have been obtained. In this study, primarily, previous studies have been updated according to significant world wide earthquake records (2307 strong ground motion records belonging to 26 earthquakes). Then, in scope of this paper, a new regression equation has been obtained and the results have been examined. In consequence of the comparisons, it has been determined that the new formula has more appropriate results in terms of the regression parameters (R2 and standard deviation). All of these regression equations are suitable for a general approximation to the topic. These equations are useful to predict the amount of displacement for regionalscale seismic landslide hazard but they are not proposed for spesific design. [ABSTRACT FROM AUTHOR]