Seismic Ground Motion Parameters Research Articles

Declustering characteristics of the North China Plain seismic belt and its effect on probabilistic seismic hazard analysis

The accurate and impartial identification of background seismic activity is an important foundation for earthquake model construction and probabilistic seismic hazard analysis (PSHA). We use the Gardner and Knopoff, Reasenberg, nearest-neighbor and stochastic declustering methods to decluster in the North China Plain seismic belt, analyzing the effect of declustering. We optimize the input parameters of the algorithms through Kolmogorov-Smirnov Poisson distribution tests (e.g., the clustering threshold of the nearest-neighbor method is set to 0.6). Four algorithms demonstrate good declustering effects, removing the impact of the strong seismicity in Tangshan while retaining similar trends to all events. The occurrence of major earthquake events can significantly impact the declustering characteristics in terms of time, space and magnitude. There is a difference in the overall hazard between the four declustering algorithms and the Fifth Generation Seismic Ground Motion Parameters Zonation Map of China. The difference in seismic hazard curves is mainly influenced by the annual average occurrence rate (background rates) and the Gutenberg-Richter b value, with the effect of the b value being more pronounced. The analysis of the effect of algorithms and their impact on PSHA can provide reference for earthquake risk assessment, engineering seismic design and disaster research.

The influence of aftershocks on seismic hazard analysis: a case study from Xichang and the surrounding areas

Abstract. In some instances, a strong aftershock can cause more damage than the mainshock. Ignoring the influence of aftershocks may lead to the underestimation of the seismic hazard of some areas. Taking Xichang and its surrounding areas as an example and based on the Seismic ground motion parameters zonation map of China (GB 18306-2015), this study used the Monte Carlo method to simulate synthetic mainshock sequences. Additionally, the Omi–Reasenberg–Jones (Omi–R–J) aftershock activity model is used to simulate the aftershock sequences that follow mainshocks above a certain magnitude threshold. Then, the mainshock and the aftershocks are combined to calculate the regional seismic hazard using ground motion prediction equations (GMPEs). Finally, the influence of aftershocks on seismic hazard analysis is examined and considered. The results show that in areas with moderate to strong seismic backgrounds, the influence of aftershocks on probabilistic seismic hazard analysis can exceed 50 %. These results suggest that the impact of aftershocks should be properly considered for future probabilistic seismic hazard analyses, especially in areas with moderate to strong seismic activity backgrounds and in areas prone to secondary disasters such as landslides and mudslides.

Seismic Hazard Analysis of China’s Mainland Based on a New Seismicity Model

Based on the seismic source model in the Fifth Generation Seismic Ground Motion Parameters Zonation Map of China (FGSGMPZMC), a new seismic fault model, the new zonation of seismic risk areas (SRAs), and the estimation of seismicity rates for 2021–2030, this study constructed a new time-dependent seismic source model of China’s mainland, and used the probabilistic seismic hazard analysis method to calculate seismic hazard by selecting the ground motion models (GMMs) suitable for seismic sources in China. It also provided the probabilities of China’s mainland being affected by earthquakes of modified Mercalli intensity (MMI) VI, VII, VIII, IX, and ≥ X in 2021–2030. The spatial pattern of seismic hazards presented in this article is similar to the pattern of the FGSGMPZMC, but shows more details. The seismic hazards in this study are higher than those in the FGSGMPZMC in the SRAs and fault zones that can produce large earthquakes. This indicates that the seismic source model construction in this study is scientific and reasonable. There are certain similarities between the results in this study and those of Rong et al. (2020) and Feng et al. (2020), but also disparities for specific sites due to differences in seismic source models, seismicity parameters, and GMMs. The results of seismic hazard may serve as parameter input for future seismic risk assessments. The hazard results can also be used as a basis for the formulation of earthquake prevention and mitigation policies for China’s mainland.

Rapid report of seismic damage to buildings in the 2022 M 6.8 Luding earthquake, China

The report summarizes the observed damage to a variety of buildings near the epicenter of the M6.8 Luding earthquake in Sichuan Province, China. They include base-isolated buildings, multi-story reinforced concrete (RC) frame buildings, and masonry buildings. The near-field region is known to be tectonically highly active, and the local intensity level is the highest, that is, 0.4g peak ground acceleration (PGA) for the design basis earthquake, in the Chinese zonation of seismic ground motion parameters. The extent of damage ranged from the weak-story collapse that claimed lives to the extensive nonstructural damage that suspended occupancy. The report highlights the first observation of the destruction of rubber bearings and viscous dampers in the isolation layer of Chinese seismically isolated buildings. It also features the rare observation of the brittle shear failure of RC columns in moment-resisting frames in a region of such a high seismic design requirement. Possible reasons that may have attributed to the reported damage are suggested by providing facts observed in the field. However, careful forensic analyses are needed before any conclusive judgment can be made.

Probabilistic Seismic Hazard Analysis of Hazara Kashmir Syntaxes and its Surrounding

Abstract The Hazara Kashmir syntaxes (HKS) is located in the western Himalayas in Pakistan that marks the easternmost proximity of the western Himalayan mountain system and is regarded as one of the most tectonically active domains of the world. In this study, the seismic ground motion parameters have been calculated for Hazara Kashmir syntaxes and its surrounding. The seismic hazard parameters were computed using probabilistic seismic hazard analysis (PSHA) and the standard Cornell–McGuire method at each grid spacing of 0.1o × 0.1o. This study encompasses the seismic records of the historical and instrumental database to establish the recurrence relationship based on an appropriate ground motion prediction equation (GMPE). Recently developed, the Boore and Atkinson (2008) next-generation attenuation (NGA) and Akkar and Bommer (2007) attenuation relationships were adopted for hazard computation. The resultant peak ground acceleration (PGA) maps and spectral intensity curves at T = 0.05 to T = 3, for 100, 250, 475, 1000, and 2500 year return periods have been estimated at bedrock level. This study concludes that the seismic provision for the building code of Pakistan needs to be revised and updated.

Research on seismic ground motion parameters applicable to the safety of rectangular shallow tunnel

The objective of this paper is to optimize the selection of seismic ground motion intensity indexes in the seismic fortification of urban shallow-buried rectangular tunnels. This paper takes a shallow-buried rectangular tunnel in a city as the research object, uses ABAQUS to establish a finite-infinite element coupling model, and selects 70 typical seismic ground motions for dynamic calculation. Using dynamic time history analysis method to study the seismic response of tunnel lining structure in terms of internal force, minimum safety factor and strain energy, and analyze their correlation with 15 seismic ground motion parameters. Selecting the seismic ground motion parameters with strong correlation, good effectiveness, and high credibility for safety evaluation. The research results show that: Peak acceleration (PGA) has a weak correlation with the seismic response of tunnel lining structures, and PGA as an independent seismic ground motion intensity index has greater uncertainty in the seismic fortification of tunnels; Peak displacement (PGD), Root-mean-square velocity (RMSV), Root-mean-square displacement (RMSD), and Specific energy density (SED) can be used as independent seismic ground motion intensity index, The linear regression model is used to evaluate the safety of the lining structure, and finally the evaluation result is verified by the incremental dynamic analysis method (IDA), which shows that the evaluation result is accurate. The research results can provide reference for the preliminary design of seismic fortification of rectangular shallow tunnels.

Multisegment Rupture Hazard Modeling along the Xianshuihe Fault Zone, Southeastern Tibetan Plateau

AbstractThe Xianshuihe fault is a remarkable strike-slip fault characterized by high slip rate (∼10 mm/yr) and frequent strong historical earthquakes. The potential for future large earthquakes on this fault is enhanced by the 2008 Mw 7.9 Wenchuan earthquake. Previous works gave little attention to the probabilities of multisegment ruptures on the Xianshuihe fault. In this study, we build five possible multisegment rupture combination models for the Xianshuihe fault. The fault slip rates and historical earthquakes are used as input constraints to model the future seismicity on the fault segments and test whether the rupture combination models are appropriate. The segment combination model, based essentially on historical ruptures, has produced the seismicity rates most consistent with the historical records, although the model with ruptures on both the entire northern section and southern section should also be considered. The peak ground acceleration values with a return period of 475 yr calculated using the modeled rates on the Xianshuihe fault for both two models are on average larger than the values of the China Seismic Ground Motion Parameters Zonation Map.

Correlation analysis of earthquake impacts on a nuclear power plant cluster in Fujian province, China

The construction of nuclear power plants in China has proceeded rapidly in recent years, and a nuclear power plant cluster is present in the coastal area of Fujian Province. Considering the lessons of the Fukushima Daiichi nuclear power plant accident, we applied the Monte Carlo approach to calculate the correlation characteristics of earthquake impacts on the nuclear power plant cluster and to assess the seismic hazards at multiple sites. Based on the seismic source zone model, seismicity model and ground-motion prediction model of the Seismic Ground Motion Parameters Zonation Map of China, many earthquake scenarios were sampled, and the possibility of multiple sites experiencing ground motions that exceed critical values at the same time were obtained. The results show that the correlation between nuclear power plants Fuqing (C) and Putian (D) is the largest and that they have a slight probability of exceeding their respective design criteria at the same time. The correlation of earthquake impacts on nuclear power plants Ningde (A) and Xiapu (B) is also high, but the probability that they simultaneously exceed their respective design criteria is very low. This study can provide a reference for the site selection of nuclear power plants.

PROBABILITY OF COSEISMIC LANDSLIDES: A NEW GENERATION OF EARTHQUAKE-TRIGGERED LANDSLIDE HAZARD MODEL

The probability of the occurrence of coseismic landslides is basically blank. In this study, the Bayesian Probability Method and the Machine Model are used to carry out the real probability of coseismic landslides of China. The first generation of coseismic landslide hazard probability map of China is produced on the basis of nine earthquake cases. They include 1999 Chi-chi, Taiwan, 2005 Kashmir, 2008 Wenchuan, 2010 Yushu, 2013 Lushan, 2013 Minxian, 2014 Ludian, 2015 Nepal, and 2017 Jiuzhaigou earthquakes. Seven of the nine earthquakes occurred in China. The 2005 Kashmir and the 2015 Nepal quakes occurred in China's neighboring areas, which can better control the accuracy of the model. All these earthquake events have detailed and complete coseismic landslide inventories. They include 306 435 landslide polygons. Considering the real earthquake landslide occurrence area, the difference of landslide size, the ratio of landslide to non-slip sample ratio, a total of 5 117 000 samples are selected. A total of 13 factors are selected. They are absolute elevation, relative elevation, slope angle, slope aspect, slope curvature, slope position, topographic humidity index, land cover, vegetation coverage percentage, fault distance, stratum, average annual precipitation, and peak ground acceleration. The Bayesian probability method is combined with the machine learning model to establish a multi-factor impact model for the probability of earthquake-triggered landslide. Then the weights of each continuous factor and the weight of each class of the classification factor are obtained. The model is applied in China considering the peak ground acceleration as the triggering factor of landslides and considering the real probability of earthquake landslides in China under different peak ground accelerations(0.1~1 g, one result per 0.1 g, a total of 10 results). In addition, combined with Seismic Ground Motion Parameters Zonation Map of China, the corresponding true probability of earthquake-triggered landslides of China is generated.

Seismic and geologic controls on spatial clustering of landslides in three large earthquakes

Abstract. The large, shallow earthquakes at Northridge, California (1994), Chi-Chi, Taiwan (1999), and Wenchuan, China (2008), each triggered thousands of landslides. We have determined the position of these landslides along hillslopes, normalizing for statistical bias. The landslide patterns have a co-seismic signature, with clustering at ridge crests and slope toes. A cross-check against rainfall-induced landslide inventories seems to confirm that crest clustering is specific to seismic triggering as observed in previous studies. In our three study areas, the seismic ground motion parameters and lithologic and topographic features used do not seem to exert a primary control on the observed patterns of landslide clustering. However, we show that at the scale of the epicentral area, crest and toe clustering occur in areas with specific geological features. Toe clustering of seismically induced landslides tends to occur along regional major faults. Crest clustering is concentrated at sites where the lithology along hillslopes is approximately uniform, or made of alternating soft and hard strata, and without strong overprint of geological structures. Although earthquake-induced landslides locate higher on hillslopes in a statistically significant way, geological features strongly modulate the landslide position along the hillslopes. As a result the observation of landslide clustering on topographic ridges cannot be used as a definite indicator of the topographic amplification of ground shaking.

POD-based dimension reduction representation of stochastic ground motion fields

In this paper, two kinds of proper orthogonal decomposition (POD) representations for simulating the non-stationary stochastic vector processes are derived based on the basic theory of POD, namely the orthogonal-random-variables-based POD representation and the random-phase-angles-based POD representation. It is clarified that the random-phase-angles-based scheme is a special case of the orthogonal-random-variables-based scheme, and the differences between them are analyzed from the number of elementary random variables and the constraint conditions. It is found that the randomness degree (the number of elementary random variables) of the non-stationary stochastic vector processes could be greatly reduced by introducing some appropriate constraint conditions. To this end, the efficient dimension reduction simulation of the non-stationary stochastic vector processes with just two elementary random variables is realized through introducing more rigorous constraints on the orthogonal random variables in the orthogonal-random-variables-based scheme. Also, the complete probability information of the stochastic processes is fully emerged. Through the numerical analysis of the ground motion stochastic field simulation, it is obtained that the relative errors of the mean and standard deviation, evolutionary power spectrum and coherence function of the non-stationary ground motion acceleration vector process are all in good agreement with the corresponding target values, which shows that the proposed method is effective and accurate. Meanwhile, in order to further verify the applicability of this method in terms of engineering characteristics upon ground motion, according to the five classes of the typical soil sites divided in “Seismic ground motion parameters zonation map of China”, 920 strong motion records are selected for comparing and analyzing the response spectrum and the Fourier amplitude spectrum of ground motion acceleration, respectively. The research shows that the simulation results of the proposed method have good consistency with the strong motion records, which lays a solid foundation for this proposed method applied in engineering applications.

Comparative Study of Seismic Ground Motion Parameters in Deep-Cut and High-Fill Engineering before and after Ground Leveling

Because of lack of flat land, more and more deep-cut and high-fill engineering are being carried out in mountainous areas. The original geological formations are greatly changed by ground leveling. Therefore, it is very important to analyze the seismic parameters before and after ground leveling. In this paper, the seismic motion parameters before and after ground leveling of deep-cut and high-fill engineering are compared by the establishment of seismic response analysis model in different geological conditions. The results show that the peak acceleration and the characteristic period of the response spectrum are lower than those before excavation; But the results change when filling on the foundation of bedrock or the foundation where original cover soil layers have already existed. The peak acceleration and characteristic period of acceleration response spectrum increase more than those ground motion parameters before filling in this site. Besides, when filling in the bedrock site, the peak acceleration magnification tended to decrease, with the increase of the filling thickness, and the characteristic period tended to increase. Therefore, seismic ground motion parameters after ground leveling can be lower than those before ground leveling in excavation area, conversely, ground motion parameters are higher in fill area.

A geolithological approach to seismic site classification: an application to the Molise Region (Italy)

Seismic site classification is a critical issue in order to reliably predict seismic ground motion parameters for the development of microzonation maps and site-specific hazard studies, addressed to territorial planning, real-time generation of shaking maps, and seismic design of engineering structures. The equivalent shear wave velocity through the topmost 30 m (VS30) is commonly assumed as the reference parameter to provide practical site classifications. Different approaches aimed at expressing local site conditions in terms of VS30 exist. Overall geological and morphological characteristics are often suggested in the technical literature as proxy to infer VS30 at a regional scale. In this study, the reliability of two commonly accepted approaches based either on the topographic slope proxy or on a basic geological classification was assessed with reference to a well-documented case study, the Molise Region (Italy). A comprehensive database of Down-Hole tests was collected, validated and processed in order to compare measured VS30 values with those inferred from proxy-based approaches. Furthermore, an up-to-date review of the geology of the area was carried out, and a novel methodology based on a geolithological approach was proposed for site classification at a regional scale. The methodology is based on the definition of a set of homogeneous geolithological complexes, and on their classification according to a statistical analysis of the measured VS30 and of the bedrock depth. Original maps of the seismic ground types were developed following classification criteria based upon the European building code for seismic design (EC8) and relevant modifications proposed in the literature. The comparison of the results obtained by the geolithological approach versus those deriving from the application of the above mentioned proxies pointed out an enhanced capability of the proposed method to fit the distribution of ground types, as assessed on the basis of the VS30 values measured in the reference area.

Site correction of ground motion in Fujian area

On the basis of the interpretation of the high-resolution satellite remote sensing images, in combination with the data of engineering geological exploration and shear-wave velocity testing, the site category-zoning map of FJ area with the scale of 1:200,000 is generated according to the site classification standard of “Code for Seismic design of Buildings” of China (GB50011 2010). By the method of Probabilistic Seismic Hazard Analysis, we obtain bedrock seismic ground motion parameters of five recurrent periods (50, 200, 500, 1000, and 2500 a) of FJ area. By using the 617 typical soil layer structures of the site classifications in FJ area, we build seismic response models of soil layers and make seismic response analysis, then obtain the statistic sample space of site amplification factors, which possess reasonable distribution and sufficient data. Considering the distribution characteristics of The Quaternary Strata in FJ area, according to the statistic zoning (mountains and coastal areas respectively) and site classifications as well as the level of bedrock importing ground motion, the site magnification-factors of ground motion in FJ area are obtained by classification statistics.

Regression analysis for seismic slope instability based on a double phase viscoplastic sliding model of the rigid block

Semi-empirical models based on Newmark’s sliding block permit the estimation of expected co-seismic displacements in relation to one or more parameters which characterize the ground motion that theoretically caused them. Taking this into consideration, a regression analysis, based on a double-phase viscoplastic (DPV) model, was developed using 96 Italian ground motion accelerograms for a total of 1,448 combinations obtained for different parametric conditions of the indefinite slope model. Repeated stability analysis, performed by means of the DPV model, allows for the assessment of the seismic instability of a slope in relation to different reached behaviour levels, as well as seismically induced permanent displacements. At these behaviour levels, co-seismic increases and possible subsequent decreases of viscoplastic shear strengths are associated. This implies that the post-seismic persistent mobility (collapse) of the slope can be obtained from the computation. On the other hand, coherently with the increasing of shear resistances during fast sliding displacements in clay soils, the seismic-forced displacements result substantially lower than corresponding values obtained by means of the rigorous Newmark’s sliding block. In addition, in relation to some seismic ground motion parameters, regression and functional border and separation curves were obtained with the aim of providing an expeditious seismic slope stability evaluation in reference to the co-seismic and post-seismic behaviour of clayey slopes. Regarding this, the real behaviour of two historical landslide events is discussed in the light of the results of the regression analysis outlined in this work.

Generation of site-dependent earthquake ground motion parameters

The generation of ground motion parameters, in the form of time histories, power spectral density functions or response spectra, specific to a site in a probabilistic format could result into an improved method of design. In the absence of enough earthquake records for a site, generation of site-dependent earthquake ground motions is the best alternative. A probabilistic method to simulate the seismic ground motion parameters specific to sites lying in earthquake prone region with a limited earthquake records is presented. Seismic hazard curves indicating the seismicity of a site and risk consistent spectral shapes and corresponding power spectral density functions are obtained using empirical relationships, and ground acceleration time histories are simulated using Monte Carlo technique. One dimensional wave propagation analysis, considering both linear and nonlinear behavior of soil overlying the bedrock is carried out to obtain the free field hazard curves and the ground motion parameters. The method is applied in generation of site-dependent ground motion parameters for three sites of Bhaktapur City of Kathmandu Valley. Major finding of the study shows that the free field hazard curves and the ground motion parameters vary from site to site, and are significantly influenced by the overlying soil characteristics of specific sites. Keywords: ground motion parameters, hazard curve, time history, response spectrum, power spectral density function, soil amplification Nepalese Journal of Engineering Vol.1(1) 2005 pp.84-91

Large, moderate, small earthquakes and seismic fortification criterion

This paper discusses the relation between two-step seismic design and the standard of probability of exceedance, and the relation of three-levels seismic ground motion parameters given by probability method and comprehensive probability method. The relative size relations of the ground motions with 2%, 10%, 63% probability of exceedance in 50 years, namely “large earthquake”, “moderate earthquake”, and “small earthquake”, are discussed through a practical example of seismic hazard analysis. The methods to determine seismic fortification criterion are discussed.

Correlation between macroseismic intensities and seismic ground motion parameters

We propose correlation relations between the macrosesimic intensity felt in Italy and displacement, velocity, acceleration, design ground acceleration obtained from synthetic seismograms modelling the ground motion generated by past seismicity. The results are in good agreement with empirical relations given by other authors and compare quite well with the few observations available in the Italian territory.

A NON-PARAMETRIC APPROACH TO ATTENUATION RELATIONS

A non-parametric multidimensional regression method is proposed for the prediction of seismic ground motion parameters. The main features which distinguish the method from standard regression procedures are: (1) The relationship between the input and output variables is not selected a priori by a prediction law, (2) an arbitrary number of input variables Can be taken into account, provided that an appropriate data base exists, and (3) the computational procedure is very simple. The results can be easily updated when new information becomes available. The method has been applied for the derivation of attenuation relations by using a combination of databases compiled by other researchers. In the majority of the cases discussed in this paper, the method was used for the prediction of horizontal peak ground acceleration as a function of magnitude and distance. In some cases, ground conditions were also taken into account. Some results on the attenuation relations of peak ground velocity and displacement, as well as Arias intensity, are also presented.

Locally derived earthquake ground motion attenuation relations for Jordan and conterminous areas

Abstract The most recent catalogue of earthquakes in Jordan and conterminous areas is used to derive formulae for the principal seismic ground motion parameters of peak ground acceleration (PGA), surface wave magnitude (M s ), Mercalli intensity (I 0 (MM)), and epicentral distance (R). In this context, empirical relations characterizing earthquake ground motion attenuation in Jordan are developed. The main purpose of this paper is to assist engineers in estimating ground motion parameters in the pre-planning and design stages of construction as well as to help seismologists in decisions concerning the installation and operation of earthquake strong motion instrumentation around the country.