Magnitude Scaling Factor Research Articles

Assessment of Liquefaction Hazard for Sites in Romania Using Empirical Models

This paper is focused on the evaluation of the liquefaction hazard for different sites in Romania. To this aim, a database of 139 ground motions recorded during Vrancea intermediate-depth earthquakes having moment magnitudes MW ≥ 6.0 is employed for the evaluation of the equivalent number of cycles for this seismic source. Several functional forms for the empirical evaluation of the equivalent number of cycles considering various seismological or engineering parameters are tested and evaluated. The regression analysis shows smaller uncertainties for the empirical models based on ground motion engineering parameters. Considering the lack of information in terms of engineering parameters, a simpler empirical model which accounts for the earthquake magnitude, source–site distance and soil conditions is selected for the liquefaction hazard analysis. Based on the proposed empirical model, specific magnitude scaling factors for Vrancea intermediate-depth earthquakes are proposed for the first time as well. The liquefaction hazard analysis is performed for sites whose seismic hazard is generated by either the Vrancea intermediate-depth seismic source or by local shallow crustal seismic sources. In the case of some of the selected sites, liquefaction phenomena were observed during past large-magnitude earthquakes. Unlike previous studies dealing with liquefaction analyses for sites in Romania, in this research, the hazard assessment is performed for various ground motion levels evaluated based on probabilistic seismic hazard assessment. Liquefaction hazard curves are constructed for each analyzed site. The results of the liquefaction hazard analysis show that this phenomenon is more likely to occur in the areas exposed to Vrancea intermediate-depth earthquakes, compared to the areas affected by local shallow earthquakes. In the case of the analyzed soil profiles from Bucharest, Craiova and Ianca, the minimum liquefaction safety factors less than one even for seismic hazard levels having mean return periods of 100 years and less.

Calibration of Pore Pressure Model for the Liquefaction Prediction of Soils Based on Behavior of Clean Sand, Magnitude Scaling Factor, and Initial Stress Level

Calibration of Pore Pressure Model for the Liquefaction Prediction of Soils Based on Behavior of Clean Sand, Magnitude Scaling Factor, and Initial Stress Level

Liquefaction potential hazard study at UIN Datokarama, Palu City, Central Sulawesi

In June 2019, the Asian Development Bank approved emergency rehabilitation and reconstruction assistance (EARR) to help Indonesia rebuild better critical infrastructure damaged by the 2018 Palu-Donggala earthquake. One of the EARR sub-projects is the reconstruction of Universitas Islam Negeri (UIN) Datokarama that suffered significant damage from the combined effects of the tsunami and earthquake. The design for the building's reconstruction incorporated better principles of deconstruction, including pile foundations to ensure the facilities are earthquake, tsunami, and liquefaction resistant. This study purpose is to evaluate liquefaction potential and estimate its severity or damage potential to structures in the reconstruction site. Liquefaction potential will be assessed in two ways, first by using soil deposits grain sizes distribution method from Japan technical standards for port and harbour facilities and second by safety factor against liquefaction (FOS) method using the SPT-based liquefaction triggering analysis with the revised magnitude scaling factor (MSF) relationship by Idriss and Boulanger. Liquefaction Potential Index (LPI) from Iwasaki will be used for estimating liquefaction severity. The analysis is performed on dataset taken from 6 boreholes in location dominated by saturated sandy soil and shallow ground water. Based on the result, liquefaction potentially triggered at various depth with consistent LPI index at > 15, The reconstruction site has a very high liquefaction risk.

Recommended b-Value for Computing Number of Equivalent Stress Cycles and Magnitude Scaling Factors for Simplified Liquefaction Triggering Evaluation Procedures

Recommended b-Value for Computing Number of Equivalent Stress Cycles and Magnitude Scaling Factors for Simplified Liquefaction Triggering Evaluation Procedures

Liquefaction Vulnerability Analysis using N-SPT Value and Grain Size Analysis on Gumbasa Irrigation Canal in the Post-Disaster Petobo Area, Sulawesi

Strong earthquakes occurred in Central Sulawesi, Indonesia, in late 2018, causing an inheritance disaster, soil liquefaction on Gumbasa Irrigation Canal at Petobo, Sulawesi. Soil liquefaction is a phenomenon of a decreasing soil bearing capacity triggered by strong vibrations in certain soil conditions. It immediately changes the soil characteristic from solid to liquid. Liquefaction vulnerability analysis was done using Idriss-Boulanger’s simplified procedure based on SPT value in several spots. The Petobo liquefaction zone has seven boreholes, five of which are located near the Gumbasa Irrigation Canal. The soil sample at those boreholes was taken to the laboratory for further soil testing using grain size analysis. The simplified procedure is intended to calculate the safety factor using Cyclic Resistance Ratio, Cyclic Stress Ratio, and Magnitude Scaling Factor. The liquefaction vulnerability analysis resulted in the AB 1 – AB 3 area near Gumbasa Irrigation Canal, which liquefied. Meanwhile, LP 1 and LP 4 are contrary. LP 1 is located upstream of the canal, whereas LP 4 the downstream. Grain size analysis yields a consistent result that AB 1 – AB 3 soil is quite scattered inside the liquefiable constraint.

CPTu-based approaches for cyclic liquefaction assessment of alluvial soil profiles

Over the years, methods to assess cyclic liquefaction potential based on piezocone penetration tests (CPTu) have been developed. This paper presents a comparative study between three CPTu-based methodologies, mainly in terms of the normalization procedures of overburden stresses, equivalent clean sand resistance, and magnitude scaling factor (MSF). Four CPTu profiles from a pilot site in southwest Portugal are thoroughly analysed with different methods, in terms of factor of safety against liquefaction, the Liquefaction Potential Index (LPI), and the Liquefaction Severity Number (LSN). The site presents very heterogeneous soil profiles, composed of alluvial deposits. Due to the presence of significant sand-silt–clay interbedded layers, the influence of transition zones and the use of different soil behaviour type index (Ic) cut-off values were also considered. From these analyses, a set of recommendations is presented for CPTu-based liquefaction assessment. Based on the extensive database of CPTu results in the pilot site area, a new classification relating LPI and LSN is proposed to assess liquefaction severity and damage.

Overview on Standards for Liquefaction Triggering Evaluation using the Simplified Method

Evidence of liquefaction during the 2017 Pohang earthquake has highlighted the urgent need to evaluate the current seismic design standard for liquefaction in Korea, particularly the liquefaction triggering standard. With the simplified method, which is the most popular method for evaluating liquefaction triggering, the factor of safety for liquefaction triggering is calculated via the cyclic stress ratio (CSR) and the cyclic resistance ratio (CRR). The parameters in the CSR and CRR have undergone changes over time based on new research findings and lessons learned from liquefaction case-histories. Hence, the current design standard for liquefaction triggering evaluation in Korea should also reflect these changes to achieve seismic safety during future earthquakes. In this study, liquefaction susceptibility criteria were discussed initially and this was followed by a review of the current liquefaction triggering codes/guidelines in other countries and Korea. Next, the parameters associated with the CSR such as the maximum ground acceleration, stress reduction factor, magnitude scaling factor, and overburden correction factor were discussed in detail. Then, the evaluation of the CRR using the SPT N-value and CPT qc-value was elaborated along with overburden and clean-sand correction factors. Based on this review of liquefaction triggering evaluation standards, recommendations are made for improving the current seismic design standard related to liquefaction triggering in Korea.

Equivalent number of uniform cycles versus earthquake magnitude relationships for fine-grained soils

In current geotechnical seismic design practice, the empirical correlation between equivalent number of uniform cycles (Neq) of shaking and earthquake magnitude (Mw) forms an integral part of liquefaction potential evaluation. This relationship, in turn, is used to derive the magnitude scaling factors that are commonly used in field-based liquefaction evaluation procedures. The Neqversus Mwrelationship for liquefaction assessment was examined for fine-grained soils using time-histories in the range 5 < Mw≤ 9, especially including strong ground motion time-histories from the latest subduction zone earthquakes with Mw> 8.0. The experimental database available from cyclic direct simple shear tests conducted on natural fine-grained soils retrieved from undisturbed soil sampling was used to obtain the cyclic shear resistance weighting curves for the study. The work presented herein has contributed to further improving the current models used to represent magnitude scaling factor (MSF) values for large earthquake magnitudes and the functional dependency of this parameter on soil type. The MSF–Mwcurve derived for low-plastic Fraser River Delta silt lies in-between the MSF curves derived for clean sand and clay, resonating with the inferences that have been made that the silt behavior can neither be considered sand-like nor clay-like.

Addressing limitations in existing ‘simplified’ liquefaction triggering evaluation procedures: application to induced seismicity in the Groningen gas field

The Groningen gas field is one of the largest in the world and has produced over 2000 billion m3 of natural gas since the start of production in 1963. The first earthquakes linked to gas production in the Groningen field occurred in 1991, with the largest event to date being a local magnitude (ML) 3.6. As a result, the field operator is leading an effort to quantify the seismic hazard and risk resulting from the gas production operations, including the assessment of liquefaction hazard. However, due to the unique characteristics of both the seismic hazard and the geological subsurface, particularly the unconsolidated sediments, direct application of existing liquefaction evaluation procedures is deemed inappropriate in Groningen. Specifically, the depth-stress reduction factor (rd) and the magnitude scaling factor relationships inherent to existing variants of the simplified liquefaction evaluation procedure are considered unsuitable for use. Accordingly, efforts have first focused on developing a framework for evaluating the liquefaction potential of the region for moment magnitudes (M) ranging from 3.5 to 7.0. The limitations of existing liquefaction procedures for use in Groningen and the path being followed to overcome these shortcomings are presented in detail herein.

Deterministic and Probabilistic Analysis of Liquefaction for Different Regions in Bihar

The built environment and human life have been regularly affected by earthquakes. One of the most catastrophic earthquake hazards is liquefaction causing failure of embankment, earth structures, foundations, natural slopes and superstructures. In this paper, three methods have been used to predict the liquefaction susceptibility of some of high seismically active regions of Bihar such as Darbhanga, Samastipur, West-Champaran and Araria Sangram. The first method is based on semi-empirical approach, given by Idriss and Boulanger (in: Proceedings of 11th International conference on soil dynamics and earthquake engineering and 3rd International conference on earthquake geotechnical engineering vol 1, pp 32–56, 2006). The stress reduction factor (rd), overburden correction factor for cyclic stress ratios Kσ, earthquake magnitude scaling factor for cyclic stress ratios (MSF) and recently modified relations has been considered in this approach. The result is obtained in form of factor of safety at particular depth beneath the ground surface. The second approach is based on Muduli’s probabilistic method (2013) and third is on relevance vector machine (RVM) method developed by Karthikeyan et al. (Eur J Environ Civ Eng 17(4):248–262, 2013). RVM model has been used to determine the liquefaction potential of soil based on standard penetration test (SPT) blow count. The SPT data has been used as input parameter for the analysis. Site coming under high seismic zone is more susceptible to liquefaction during earthquake. This concludes that earthquake magnitude plays very important role for the assessment of liquefaction, irrespective of soil type and water table of the site. This paper contains the deterministic and probabilistic analysis of liquefaction behavior of soil.

Characterisation of the Groningen subsurface for seismic hazard and risk modelling

AbstractThe shallow subsurface of Groningen, the Netherlands, is heterogeneous due to its formation in a Holocene tidal coastal setting on a periglacially and glacially inherited landscape with strong lateral variation in subsurface architecture. Soft sediments with low, small-strain shear wave velocities (VS30around 200 m s−1) are known to amplify earthquake motions. Knowledge of the architecture and properties of the subsurface and the combined effect on the propagation of earthquake waves is imperative for the prediction of geohazards of ground shaking and liquefaction at the surface. In order to provide information for the seismic hazard and risk analysis, two geological models were constructed. The first is the ‘Geological model for Site response in Groningen’ (GSG model) and is based on the detailed 3D GeoTOP voxel model containing lithostratigraphy and lithoclass attributes. The GeoTOP model was combined with information from boreholes, cone penetration tests, regional digital geological and geohydrological models to cover the full range from the surface down to the base of the North Sea Supergroup (base Paleogene) at ~800 m depth. The GSG model consists of a microzonation based on geology and a stack of soil stratigraphy for each of the 140,000 grid cells (100 m × 100 m) to which properties (VSand parameters relevant for nonlinear soil behaviour) were assigned. The GSG model serves as input to the site response calculations that feed into the Ground Motion Model. The second model is the ‘Geological model for Liquefaction sensitivity in Groningen’ (GLG). Generally, loosely packed sands might be susceptible to liquefaction upon earthquake shaking. In order to delineate zones of loosely packed sand in the first 40 m below the surface, GeoTOP was combined with relative densities inferred from a large cone penetration test database. The marine Naaldwijk and Eem Formations have the highest proportion of loosely packed sand (31% and 38%, respectively) and thus are considered to be the most vulnerable to liquefaction; other units contain 5–17% loosely packed sand. The GLG model serves as one of the inputs for further research on the liquefaction potential in Groningen, such as the development of region-specific magnitude scaling factors (MSF) and depth–stress reduction relationships (rd).

The impact evaluation of soil liquefaction on low-rise building in the Meinong earthquake

This paper presents major preliminary observations on the liquefaction-induced damages in the Meinong earthquake (ML = 6.4). The severe damages to buildings centered on Huian and Sanmin Streets in Tainan City where the places were reclaimed fish or farm ponds with poor construction quality from many decades ago. To better understand the effect due to the soil liquefaction at these sites, the information provided by the in situ 13 Standard Penetration Test boreholes and 5 Cone Penetration Test soundings accompanying with the PGAs derived from the near seismographs was used to conduct the soil liquefaction evaluation by the Seed method (Seed et al. in J Geotech Eng ASCE 111(12):1425–1445, 1985) when subject to the Meinong earthquake. The liquefaction potential index (LPI) was then evaluated accordingly. From the results, it was found that the estimated damage severity was not consistent to the field conditions if the local site effect was not taken into account. To better reflect the site response in such sites, the sites’ PGAs in the PGA contour map were multiplied by 1.5 times to quantify the amplification effects due to the soft geological condition. In addition, the PGAs based on other simple approaches were evaluated as well for comparison. Besides, the effects of fines content and magnitude scaling factor were also discussed in this paper. After that, several common simplified methods were also used to calculate the LPI when subject to the Meinong earthquake in order to evaluate the applicability of these simplified methods.

Comparison of Numerical and Analytical Liquefaction Analyses of Tailings

The seismic performance of a tailings impoundment can be adversely affected by the behavior of the retained tailings. However, there remains considerable uncertainty in tailings liquefaction analysis. Twenty cyclic simple shear tests conducted on tailings from a gold mine in Quebec, Canada, were simulated numerically. The simulations indicated that the dynamic behavior of tailings could be modelled reasonably well, except that the weighted cyclic resistance curve of the tailings differed from that of clean sand which was used to develop the constitutive model (UBCSAND). An (N1)60-CS value of 10 blows/30 cm was estimated for the tailings based on calibration at a CSR of 0.10 for 15 cycles of loading. Numerical simulation of the behavior of a 20-m-high deposit of tailings during an earthquake (Mw = 5.9) indicated liquefaction of the upper 8 m of tailings. Liquefaction analysis using the Simplified method with published magnitude scaling factors (MSF) did not predict the occurrence of liquefaction. The use of MSF values calculated from the laboratory testing predicted liquefaction in the upper 8 m of tailings, corresponding quite well with the numerical simulation. The results indicate that both analytical and numerical methods can be used to evaluate the potential for tailings liquefaction under seismic loads.

Spatial variation of magnitude scaling factors during the 2010 Darfield and 2011 Christchurch, New Zealand, earthquakes

The combination of well-documented liquefaction response during the Darfield and Christchurch, New Zealand, earthquakes, densely-recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to investigate the significance of the spatial variation of magnitude scaling factors (MSF) on liquefaction triggering. Towards this end, MSF were computed at 15 SMS sites across Christchurch and its surroundings using two established approaches. Trends in the spatial variation of the MSF computed using number of equivalent cycles (neq) from both approaches were similar, with the spatial variation being more significant for the Christchurch earthquake than the Darfield earthquake. However, there was no consistent trend for regions with lower computed MSF having experienced more severe or widespread liquefaction. Additionally, there is a general correlation between MSF and amax, but because amax ranges more widely than MSF it has a greater influence on the resulting seismic demand imposed on the soil than MSF does. Nevertheless, the spatial variation of the MSF is deemed significant enough that it warrants being considered for incorporation into future variants of simplified liquefaction evaluation procedures.

The role of biomonitoring in chemical risk assessment: The contribution of the Scientific Committee of Occupational Toxicology of the International Commission on Occupational Health

The combination of well-documented liquefaction response during the Darfield and Christchurch, New Zealand, earthquakes, densely-recorded ground motions for the events, and detailed subsurface characterization provides an unprecedented opportunity to investigate the significance of the spatial variation of magnitude scaling factors (MSF) on liquefaction triggering. Towards this end, MSF were computed at 15 SMS sites across Christchurch and its surroundings using two established approaches. Trends in the spatial variation of the MSF computed using number of equivalent cycles (neq) from both approaches were similar, with the spatial variation being more significant for the Christchurch earthquake than the Darfield earthquake. However, there was no consistent trend for regions with lower computed MSF having experienced more severe or widespread liquefaction. Additionally, there is a general correlation between MSF and amax, but because amax ranges more widely than MSF it has a greater influence on the resulting seismic demand imposed on the soil than MSF does. Nevertheless, the spatial variation of the MSF is deemed significant enough that it warrants being considered for incorporation into future variants of simplified liquefaction evaluation procedures.

CPT-Based Liquefaction Triggering Procedure

AbstractA probabilistic cone penetration test (CPT) based liquefaction triggering procedure for cohesionless soils is derived using a maximum likelihood method with an updated case history database. The liquefaction analysis framework includes revised relationships for the magnitude scaling factor (MSF) and for estimating fines contents from CPT data when laboratory test data are not available. The updated case history database and methodology for developing the liquefaction correlation are described. Measurement and estimation uncertainties, the potential effects of false positives and false negatives in the case history database, and the effects of the choice-based sampling bias in the case history database are accounted for. Sensitivity analyses showed that the position of the most likely triggering curve and the magnitude of the total error term are reasonably well constrained by the data. The sensitivity study provides reasonable bounds on the effects of different interpretations, from which probabil...

Magnitude scaling factors in liquefaction triggering procedures

A revised magnitude scaling factor (MSF) relationship for CPT-based and SPT-based liquefaction triggering analyses is presented in this paper. The revised MSF relationship incorporates functional dependency on the soil characteristics [represented by clean sand equivalent penetration resistances in the present form] as well as on earthquake magnitude. The revisions in MSF are based on the examination of cyclic testing results for a broad range of soil types and densities, analyses of strong ground motion records to develop relationships for the equivalent number of loading cycles for different soil properties, and the synthesis of those results into an MSF relationship suitable for implementation in practice. A separate study [2] showed that use of the revised MSF relationship in CPT-based and SPT-based liquefaction triggering procedures is well-supported by the case history databases. Other factors known to fundamentally influence the MSF are discussed.

Seismic Demand of the Liquefaction Potential with Equivalent Number of Cycles for Probabilistic Seismic Hazard Analysis

Equivalent number of cycles (Ncyc) is a significant factor in assessing liquefaction potential during earthquakes. However, the effects of Ncyc are considered a deterministic value by using a magnitude scaling factor, and the uncertainties of these effects have not been included in the current design practice. This paper calculates Ncyc within the soil mass by deconvolution analysis as a function of the period of soil layer from the ground surface (Ts) and the soil property (b) using a wide range of acceleration time histories. The predictive model of Ncyc is developed as variable dependent on earthquake magnitude, peak ground acceleration (PGA), and ratio of spectral acceleration, Ts and b. Then, the Ncyc model is combined with the ground-motion prediction equation of PGA and the prediction equation of seismic shear-stress reduction coefficient (rd) to obtain the prediction equation of the seismic demand of the liquefaction potential (K1cyc). The standard deviation of K1cyc is also modeled on the basis of the aleatory variability of PGA, rd, and Ncyc with correlations between these residuals. This predictive model of K1cyc is implemented in probabilistic seismic hazard analysis (PSHA) to show the impact of these uncertainties on design practice.

Prediction of cyclic resistance ratio for silty sands and its applications in the simplified liquefaction analysis

Liquefaction resistance of granular soils is commonly characterized by the cyclic resistance ratio (CRR) in the simplified shear stress procedure of liquefaction potential assessment. This parameter is commonly estimated by cyclic tests on reconstituted samples or empirical correlations between liquefied/non-liquefied case histories. The current study employs results of cyclic triaxial tests on reconstituted soil specimens and presents a predictive equation for cyclic resistance ratio (CRR) of clean and silty sands. The CRR equation is a function of relative density, effective mean confining pressure, non-plastic fines content, number of harmonic cycles for liquefaction onset, and some other basic soil properties. It is demonstrated that the developed relationship obtains reasonable accuracy in the prediction of laboratory-based CRR. Based on the developed CRR model, new relationships are then presented for the coefficient of effective overburden pressure (Kσ) and magnitude scaling factor (MSF), two important modification factors in the simplified shear stress procedure. These new modification factors are then compared with those recommended by previous researchers. Finally, the possible application of the proposed CRR model in field condition is shown for a specific case. This study provides a preliminary insight into the liquefaction resistance of silty sands prior to the complementary laboratory studies.

Comparison of Nonlinear Time Domain Site Response Analysis Subjected to Earthquake Provokes-Case Study

The present paper aims to characterize the nonlinear time domain seismic site response analysis taking into consideration geomorphological conditions, geotechnical and geophysical parameters by use of generated geotechnical based GUI computer software. In this paper a case study on ground response analysis of a seismic geotechnical site response analysis on Damghan earth dam in Semnan province of Iran during the Kahak earthquake (Ml5.7, 2007) after the magnitude-scaling factor is presented. For site characterization, deep site investigations have been undertaken and the nonlinearity on site response for the selected site with assumption of elastic and rigid half space bedrock by use of nonlinear standard hyperbolic model was evaluated. The modeling was implemented using the combination of several computer codes with MATLAB programming tool and their results over a number of geotechnical areas were compared to each other. The key factor in this work was to develop and use Abbas Converter and the present research shows its ability on site response analyses procedure.