Search

Understanding of lithosphere dynamics, tectonic stress localization, earthquake occurrences, and seismic hazards has significantly advanced during the last decades. Meanwhile, despite the major advancements in geophysical sciences, yet we do not see a decline in earthquake disaster impacts and losses. Although earthquake disasters are mainly associated with significant vulnerability of society, comprehensive seismic hazards assessments and earthquake forecasting could contribute to preventive measures aimed to reduce impacts of earthquakes. Modeling of lithosphere dynamics and earthquake simulations coupled with a seismic hazard analysis can provide a better assessment of potential ground shaking due to earthquakes. Here we present a block-and-fault dynamics (BAFD) model, which simulates earthquakes due to lithosphere dynamics and allows for studying the influence of fault network properties and regional movements on seismic patterns. The model's performance is analyzed in terms of reproduction of basic features of the observed seismicity such as the frequency-magnitude relationship, clustering of earthquakes, occurrences of large events, fault slip rates, and earthquake mechanisms. Several studies related to the application of the BAFD model to the following earthquake-prone regions are reviewed: the southeastern Carpathians, Caucasus, the western India, Tibet-Himalaya, and the Sunda Arc. We examine then a new approach to seismic hazard analysis, which is based on instrumentally recorded, historical and BAFD-simulated earthquakes, and analyze how earthquake modeling can assist in hazard assessment. Finally, we discuss perspectives in modeling of earthquake occurrences and improvements in hazard assessment.

We study the spatio-temporal characteristics of earthquakes, and find that power laws and allometric growth laws are both statistically significant in the seismic dataset. For further analyzing the complexity of earthquake sequence, an approach of weighted earthquake networks modeling is presented with using the seismic and rock mass datasets. The rock masses covering the entire region are used to divide the region into a lot of small areas. It is shown that the distributions of connectivities and link weights both follow power law decay forms. The discovery of allometric growth laws is important for studying the dynamics of massive earthquakes. The suggested earthquake network is helpful to study the interactions between rock masses and expand a research prototype for modeling seismicity on complex networks.

The inelastic behavioral characteristics of three RC buildings having 6-, 10- and 20-stories under near-source multi-component earthquake excitations are investigated. Ten earthquake records are used in the analysis to cover a wide range of vertical to horizontal spectral ratios. The performances of the buildings are evaluated through the roof displacements, the maximum story drift ratios and the maximum axial forces and strain ductility factors in the building members.Four analysis cases are considered for each earthquake including, one lateral earthquake component (X-case), two lateral earthquake components (XY-case), one lateral earthquake component accompanied with the vertical earthquake component (XZ-case) and two lateral earthquake components accompanied with the vertical earthquake component (XYZ-case). The results obtained in this study indicate that the multi-component effect of the earthquakes has a considerable effect on the axial forces and strain ductility factors of the building columns although it does not significantly affect the building lateral-deformation response. Keywords: 3-D analysis, Inelastic analysis, Multi-component earthquake, RC buildings, Vertical earthquake

The seismic performance of an important structure in Christchurch, New Zealand was well-documented during the 2010–2011 Canterbury earthquake sequence. Minor ground deformation and negligible-to-minor structural damage occurred during the primary events of the sequence, except for the 22 February 2011 Mw6.2 Christchurch earthquake, which produced differential movement of the basement mat and architectural and structural damage. This case history is evaluated to garner insights. Static settlements are estimated to establish the pre-seismic conditions of the building. Dynamic nonlinear effective stress soil-structure-interaction analysis are performed for the primary events of the Canterbury earthquake sequence using FLAC2D with the PM4Sand constitutive model to capture the cyclic response of the key soil units. The analytical results indicate the post-Canterbury earthquake sequence measured differential mat movements were primarily due to the earthquake events. A thin liquefiable layer, which historic maps indicate is now a buried stream deposit, is largely responsible for the ground movements. A medium dense sandy gravel also appeared to contribute significantly to the observed foundation movements.

The purpose of this study is to verify fault modeling in the source region of the 1940 Shakotan-Oki earthquake using active faults offshore of Japan. Tsunami heights simulated in previous studies are found to be lower than observed levels, which makes it difficult to explain historical tsunami records of this earthquake. However, the application of appropriate slip magnitudes in the fault models may explain these differences. In the “Project for the Comprehensive Analysis and Evaluation of Offshore Fault Informatics (the Project),” a new fault model is constructed using marine seismic data and geological and geophysical data compiled by the Offshore Fault Evaluation Group, Japan Agency for Marine-Earth Science and Technology (JAMSTEC) as part of the Project for Fault Evaluation in the Seas around Japan (Ministry of Education, Culture, Sports, Science and Technology, MEXT). Single-channel and multichannel reflection seismic data were used that includes information from a new fault identified in previous surveys. We investigated fault geometries and their parameters using the above data. Here, we show that the geometric continuity of these faults is adjusted by increasing the magnitude of fault slip. Standard scaling laws are applied on the basis of strong ground motion of the fault parameters, and the validity of the fault model is examined by comparing tsunami heights along the Japanese coastline from historically observed records with tsunami height from simulation analysis. This verification quantitatively uses Aida’s K and κ scale and variance parameters. We determine that the simulated tsunami height determined using the new model approach the heights observed historically, which indicates that the model is valid and accurate for the source region.

Current computational resources and physical knowledge of the seismic wave generation and propagation processes allow for reliable numerical and analytical models of waveform generation and propagation. From the simulation of ground motion, it is easy to extract the desired earthquake hazard parameters. Accordingly, a scenario-based approach to seismic hazard assessment has been developed, namely the neo-deterministic seismic hazard assessment (NDSHA), which allows for a wide range of possible seismic sources to be used in the definition of reliable scenarios by means of realistic waveforms modelling. Such reli- able and comprehensive characterization of expected earthquake ground motion is essential to improve building codes, particularly for the protection of critical infrastructures and for land use planning. Parvez et al. (Geophys J Int 155:489–508, 2003) published the first ever neo-deterministic seismic hazard map of India by computing synthetic seismograms with input data set consisting of structural models, seismogenic zones, focal mechanisms and earthquake catalogues. As described in Panza et al. (Adv Geophys 53:93–165, 2012), the NDSHA methodology evolved with respect to the original formulation used by Parvez et al. (Geophys J Int 155:489–508, 2003): the computer codes were improved to better fit the need of producing real- istic ground shaking maps and ground shaking scenar- ios, at different scale levels, exploiting the most significant pertinent progresses in data acquisition and modelling. Accordingly, the present study supplies a revised NDSHA map for India. The seismic hazard, expressed in terms of maximum displacement (Dmax), maximum velocity (Vmax) and design ground acceleration (DGA), has been extracted from the synthetic signals and mapped on a regular grid over the studied territory.

International audience; We investigate temporal variations of the polarization anomaly of surface waves (Rayleigh and Love) relative to an isotropic medium, before and after the 2008 June 13, Iwate-Miyagi Nairiku earthquake (Mw = 6.9) in Japan, using passive image interferometry. We use continuous data records of 20 high-sensitivity three-component seismic stations (National Institute for Earth Sciences and Disaster Resilience—NIED Hi-net) from mid-2007 to the end of 2009. We compute cross-correlations of ambient seismic noise between each pair of stations, in the frequency range of 0.08-0.22 Hz. The temporal variations of the surface wave polarization show slow and weak variations due to seasonal changes to which rapid and strong variations are superposed at the time of the earthquake, and more surprisingly, also a month and a half before the earthquake. Strong changes in the polarization of surface waves might be related to changes in the distribution of crack orientation affecting seismic anisotropy.

This work focuses on the evaluation of the seismic hazard for Romania using earthquake catalogues generated by a Monte Carlo approach. The seismicity of Romania can be attributed to the Vrancea intermediate-depth seismic source and to 13 other crustal seismic sources. The recurrence times of large magnitude seismic events (both crustal and subcrustal), as well as the moment release rates are computed using simulated earthquake catalogues. The results show that the largest contribution to the overall moment release for the crustal seismic sources is from the seismic regions in Bulgaria, while the seismic regions in Romania contribute less than 5% of the overall moment release. In addition, the computations show that the moment release rate for the Vrancea subcrustal seismic source is about ten times larger than that of all the crustal seismic sources. Finally, the Monte Carlo approach is used to evaluate the seismic hazard for 20 cities in Romania with populations larger than 100,000 inhabitants. The results show some differences between the seismic hazard values obtained through Monte-Carlo simulation and those in the Romanian seismic design code P100-1/2013, notably for cities situated in the western part of Romania that are influenced by local crustal seismic sources.

Seismic surges and landslides are both major secondary mountain hazards during an earthquake. This paper investigates earthquake- and landslide-induced composite surges through large-scale shaking table water tank model experiments. A series of tests were conducted for various initial water depths, peak ground accelerations, slide impact velocities, and slide volumes. Based on the results of the tests, the effects of these parameters on the maximum wave heights of the earthquake- and landslide-induced composite surges were analyzed. An amplification coefficient of seismic surges was defined, and the prediction equation for the amplification coefficient was developed through non-dimensional multiple linear regression analysis. Then, an empirical equation for the maximum wave heights of the composite surges was developed based on the amplification coefficient and Demirel’s method. This equation provides a calculation method for earthquake- and landslide-induced composite surge waves.

Strong ground shaking during earthquakes can greatly affect the ancient monuments and subsequently demolish the human heritage. On October 12th 1992, a moderate earthquake (Ms = 5.8) shocked the greater Cairo area causing widespread damages. Unfortunately, the focus of that earthquake is located about 14 km to the south of Zoser pyramid. After the earthquake, the Egyptian Supreme council of antiquities issued an alarm that Zoser pyramid is partially collapsed and international and national efforts are exerted to restore this important human heritage that was built about 4000 years ago. Engineering and geophysical work is thus needed for the restoration process. The definition of the strong motion parameters is one of the required studies since seismically active zone is recorded in its near vicinity. The present study adopted the stochastic method to determine the peak ground motion (acceleration, velocity and displacement) for the three largest earthquakes recorded in the Egypt’s seismological history. These earthquakes are Shedwan earthquake with magnitude Ms = 6.9, Aqaba earthquake with magnitude Mw = 7.2 and Cairo (Dahshour earthquake) with magnitude Ms = 5.8. The former two major earthquakes took place few hundred kilometers away. It is logic to have the predominant effects from the epicentral location of the Cairo earthquake; however, the authors wanted to test also the long period effects of the large distance earthquakes expected from the other two earthquakes under consideration. In addition, the dynamic site response was studied using the Horizontal to vertical spectral ratio (HVSR) technique. HVSR can provide information about the fundamental frequency successfully; however, the amplification estimation is not accepted. The result represented as either peak ground motion parameters or response spectra indicates that the effects from Cairo earthquake epicenter are the largest for all periods considered in the present study. The level of strong motion as indicated by peak ground acceleration reaches the value of 250 gals which is considerably high. At the end, it is worth to mention that the information resulted from the present work may be useful for the planned restoration decision of the Zoser pyramid site.

The tunnel industry has considered that tunnels, especially tunnels in rock, are naturally resistant to earthquake action, including faulting, shaking, deflection and ground failure. As the number of case histories of tunnels subject to earthquake action has increased, the industry has started to recognize that, although tunnels in rock have good resistance against earthquakes generating peak ground accelerations (PGA) lower than 0.5 g, it is important to include the dynamic forces and displacements generated by seismic ground motions in the design process to obtain a more reliable design. These additional earthquake forces impact the final design, potentially requiring changes to the ground support and additional reinforcement of the concrete lining, as illustrated by case histories presented in this paper.

The main goal of this work is to: (1) argue for the importance of a physically-based probabilistic seismic hazard analysis (pb-PSHA) methodology and show examples to support the argument from recent events, (2) demonstrate the methodology with the ground motion simulations of May 28, 1998, Mw = 5.5 Ras-Elhekma earthquake, north Egypt. The boundaries for the possible rupture parameters that may have been identified prior to the 1998 Ras-Elhekma earthquake were estimated. A range of simulated ground-motions for the Ras-Elhekma earthquake was “predicted” for frequency 0.5–25 Hz at three sites, where the large earthquake was recorded, with average epicentral distances of 220 km. The best rupture model of the 1998 Ras-Elhekma earthquake was identified by calculated the goodness of fit between observed and synthesized records at sites FYM, HAG, and KOT. We used the best rupture scenario of the 1998 earthquake to synthesize the ground motions at interested sites where the main shock was not recorded. Based on the good fit of simulated and observed seismograms, we concluded that this methodology can provide realistic ground motion of an earthquake and highly recommended for engineering purposes in advance or foregoing large earthquakes at non record sites. We propose that there is a need for this methodology for good-representing the true hazard with reducing uncertainties.

WOS: 000438615600008 Over the years, several local and regional seismic hazard studies have been conducted for the estimation of the seismic hazard in Turkey using different statistical processing tools for instrumental and historical earthquake data and modeling the geologic and tectonic characteristics of the region. Recently developed techniques, increased knowledge and improved databases brought the necessity to review the national active fault database and the compiled earthquake catalogue for the development of a national earthquake hazard map. A national earthquake strategy and action plan were conceived and accordingly with the collaboration of the several institutions and expert researchers, the Revision of Turkish Seismic Hazard Map Project (UDAP-C-13-06) was initiated, and finalized at the end of 2014. The scope of the project was confined to the revision of current national seismic hazard map, using the state of the art technologies and knowledge of the active fault, earthquake database, and ground motion prediction equations. The following two seismic source zonation models are developed for the probabilistic earthquake hazard analysis: (1) Area source model, (2) Fault and spatial smoothing seismic source model (FSBCK). In this study, we focus on the development and the characterization of the Fault Source model, the background spatially smoothed seismicity model and intrinsic uncertainty on the earthquake occurrence-rates-estimation. Finally, PSHA results obtained from the fault and spatial smoothed seismic source model are presented for 43, 72, 475 and 2475 years return periods (corresponding to 69, 50, 10, and 2% probability of exceedance in 50 years) for PGA and 5% damped spectral accelerations at 0.2 and 1.0 s. AFAD (Disaster and Emergency Management Authority of Turkey) [UDAP-C-13-16] First, we would like to express our gratitude to Sinan Akkar for his kind coordination of the project titled as "The update of the seismic hazard maps of Turkey'', and to Mustafa Erdik for his suggestions and comments, which helped us to considerably improve the project. We would like to thank various local researchers who gave us feedback and comments: Tolga Yilmaz, Ahmet Yakut, from Middle East Technical University; Murat Utkucu from Sakarya University. We also acknowledge Laurentiu Danciu from ETHZ, Roberto Basili from INGV, and Tuba Eroglu Azak who wrote and improved the codes and some scripts used in the calculation of some parameters. The study has been sponsored by AFAD (Disaster and Emergency Management Authority of Turkey) under Project Code UDAP-C-13-16. We would also like to thank Dr. Baumont for his review and suggestions for the improvement of the manuscript.

The present paper discusses the use of an integrated remote sensing and Geographical Information System (GIS) techniques for evaluation of seismic hazard areas in Syria. In the proposed approach, we have used the Advanced Spaceborne Thermal Emission and Reflection Radiometer (Aster) satellite data, digital elevation data (30 m resolution), earthquake data, and active tectonic maps. Many important factors for evaluation of seismic hazard were identified and corresponding thematic data layers (past earthquake epicenters, active faults, digital elevation model, and slope) were generated. A numerical rating scheme has been developed for spatial data analysis using GIS to identify ranking of parameters for the evaluation of seismic hazard. The resulting earthquake potential map delineates the area into different relative susceptibility classes: high, moderate, low and very low. The potential earthquake map was validated by correlating the obtained different classes with the local probability that produced using conventional analysis of observed earthquakes. Using earthquake data of Syria and the peak ground acceleration (PGA) data are included in the model to develop final seismic hazard map based on Gutenberg-Richter ( a and b values) parameters and the concepts of local probability and recurrence time. The application of the proposed technique in Syrian region indicates that this method provides good estimate of seismic hazard map compared to those developed from traditional techniques deterministic (DSHA) and probabilistic seismic hazard (PSHA). For the first time, we have used numerous parameters in preparation of seismic hazard map. The evaluation of seismic hazard maps using the proposed model is found to be very realistic.

In conventional seismic hazard analysis, uniform distribution over area and magnitude range is assumed for the evaluation of source seismicity which is not able to capture peculiar characteristic of near-fault ground motion well. For near-field hazard analysis, two important factors need to be considered: (1) rupture directivity effects and (2) occurrence of scenario characteristic ruptures in the nearby sources. This study proposed a simple framework to consider these two effects by modifying the predictions from the conventional ground motion model based on pulse occurrence probability and adjustment of the magnitude frequency distribution to account for the rupture characteristic of the fault. The results of proposed approach are compared with those of deterministic and probabilistic seismic hazard analyses. The results indicate that characteristic earthquake and directivity consideration both have significant effects on seismic hazard analysis estimates. The implemented approach leads to results close to deterministic seismic hazard analysis in the short period ranges (T 1.0 s). Finally, seismic hazard maps based on the proposed method could be developed and compared with other methods.

During the 2011 Great East Japan earthquake occurring at the north-east pacific region, serious secondary disasters caused by collision of drifting containers or ships occurred in various structures when tsunami came. Disaster deterioration caused by earthquake and drifting object impact during earthquake and tsunami has become another problem. This study presents an effective method to evaluate the accumulative response of steel bridge under earthquake and large drifting object impact due to tsunami flow, and the earthquake and tsunami come from the same fault motion. The main innovation has to do with the quantification of the earthquake effect and the ship-impact effect due to earthquake-induced tsunami directly into ductility demands, a phenomenon which has not been studied in the past. A series of seismic response analysis and impact analysis are carried out, and damage to the main tower of bridge is evaluated by means of elastic-plastic finite element analysis. This study shows that piers of main tower of bridge can be severely damaged due to the earthquake and ship impact effect compared to only impact effect. An effective evaluated method that could be useful for evaluating damage of lifeline engineering under such mega earthquake and tsunami is proposed.

Summary Simplified approaches for examining structural system response under sequential earthquake and tsunami loading are helpful for understanding response trends. To aid understanding, nonlinear (constant-ductility) response spectra are developed for elastoplastic single degree of freedom systems subjected to seismic loads followed by hydrodynamic tsunami loads. The forcing function is composed of long-duration earthquake motion concatenated with a range of tsunami hydrodynamic forces that are proportional to the pseudo-spectral acceleration produced by the earthquake motion. The constant-ductility spectra are thus constructed for scenarios where the loading imposed by one hazard is not dominant over the other. The spectra and basic intensity measures indicate that the amplification of response for sequential earthquake and tsunami loading over the earthquake only case is most significant for systems with long natural periods and high-ductility capacity under seismic loading. Copyright © 2017 John Wiley & Sons, Ltd.

The historical earthquake of the 1894 in Atalanti, Greece, produced widespread liquefaction effects on the broader coastal area. Although this earthquake has been extensively studied in the past, its magnitude still remains controversial. In the present study, we propose an indirect method for assessing its magnitude by simulating the ground motion and liquefaction effects, caused by a scenario earthquake with the characteristics of the 1894 event, at several sites located at the coastal zone of Atalanti Bay. For this purpose, we utilize information about the near‐surface soil conditions obtained by geophysical tools, data of recent seismic events, and results of stochastic simulation of strong ground motion for the scenario earthquake of the 1894 event. We confirm the high liquefaction potential of the investigated sites and establish that the low limit of magnitude ( M w ) for the 1894 earthquake is equal to 7.0. Electronic Supplement: Results of liquefaction analysis.

Near-field ground motions are significantly severely affected on seismic response of structure compared with far-field ground motions, and the reason is that the near-source forward directivity ground motions contain pulse-long periods. Therefore, the cumulative effects of far-fault records are minor. The damage and collapse of engineering structures observed in the last decades’ earthquakes show the potential of damage in existing structures under near-field ground motions. One important subject studied by earthquake engineers as part of a performance-based approach is the determination of demand and collapse capacity under near-field earthquake. Different methods for evaluating seismic structural performance have been suggested along with and as part of the development of performance-based earthquake engineering. This study investigated the results of illustrious characteristics of near-fault ground motions on the seismic response of reinforced concrete (RC) structures, by the use of Incremental Nonlinear Dynamic Analysis (IDA) method. Due to the fact that various ground motions result in different intensity-versus-response plots, this analysis is done again under various ground motions in order to achieve significant statistical averages. The OpenSees software was used to conduct nonlinear structural evaluations. Numerical modelling showed that near-source outcomes cause most of the seismic energy from the rupture to arrive in a single coherent long-period pulse of motion and permanent ground displacements. Finally, a vulnerability of RC building can be evaluated against pulse-like near-fault ground motions effects.

The Niigata-ken Chuetsu-Oki Earthquake (hereinafter referred to as “the NCO Earthquake”) occurred in 2007 with a hypocenter very close to Kashiwazaki-Kariwa Nuclear Power Station of Tokyo Electric Power Company Holdings, Inc. (hereinafter referred to as “TEPCO”). TEPCO's subsequent plant investigation, earthquake response analysis using observation records and large-scale shaking table tests have provided us valuable experiences, including the fact that safety related components were undamaged and non-safety-related components sustained only limited damage. This paper describes the time history analysis of components whose damage states are based on excessive stress or deformations due to elastoplastic behavior. The input ground motions for the time history response analysis were records from the NCO Earthquake. The components were modeled with simplified bi-linear models representing their load-deflection characteristics; one of the analysis results was the maximum ductility factor of each component when subjected to the NCO Earthquake motions. Based on the assumption that increasing ductility factor values is correlated with damage to components, this paper discusses the threshold of the ductility factor that affected to the damages to components. This paper concludes that the ductility factor could be considered as a damage indicating parameter (DIP) to components whose damage states are a function of plastic deformation. If this ductility factor is reflected in the seismic design, it is considered to contribute to the improvement of the diversity and the reliability of the seismic design system of nuclear power plants.

Numerical modeling of dynamic wave processes in heterogeneous media allows to investigate the earthquake stability of different constructions. The aim of this work is to study the earthquakes impact on the ground buildings and underground facilities. The use of grid-characteristic method makes possible to take into account the physics of arising wave processes. The use of systems of hierarchical grids allows to perform a calculation of seismic waves directly from the earthquake source to the ground buildings and underground facilities. The arising area of cracks in this ground building (two-storied houses) at different times from different types of seismic waves is studied. Also the impact of earthquake on the underground facilities is considered. The dynamical arising of cracks and destruction into the underground facilities made from different types of reinforced concrete due to the impact of different types of seismic waves is investigated in this paper. The results demonstrate a possibility of investigation earthquake stability of underground facilities and living buildings using modeling of seismic waves propagation directly from the earthquake centers.

A large set of earthquake records from the highly instrumented Samoa Channel bridge-ground system has been compiled and made available by the California Geological Survey. During six seismic events, more than 30 data channels have been documenting the seismic response of the bridge, abutments, and adjacent ground surface. Of special interest is the response of one of the bridge piers with records at the deck level, pile cap and within the underlying pile foundation. Response of this pile foundation is compared to that of the ground as documented by the nearby Eureka geotechnical downhole array. In this paper, records from the strongest to date 2010 Ferndale earthquake (PGA of about 0.16 g), along with other available low-amplitude events (2007–2014) are employed to evaluate the ground, pile foundation, and overall bridge seismic response. Spatial variation of the recorded motions is examined. Linear and nonlinear response of the ground and the bridge are assessed using system identification techniques. During the strong shaking phase of the 2010 Ferndale Earthquake, a clear and significant stiffness reduction was observed in the column as well as in the foundation of the instrumented pier.

The Gyeong-Ju earthquake in the magnitude of 5.8 on the Richter scaleoccurred in September 12, 2016. Because there are many nuclear power plants (NPP) near the epicenter of the Gyeong-Ju earthquake, the seismic stability of nuclear power plants is becoming a social problem. In order to evaluate the safety of seismically isolated NPP, the seismic response of a NPP subjected to the Gyeong-Ju earthquake was compared with those of 30 sets of artificial earthquakes corresponding to the nuclear standard design spectrum (NSDS). A 2-node model and a simple beam-stick model were used for the seismic analysis of seismically isolated NPP structures. Using 2-node model, the effect of internal temperature rise, decrease of shear stiffness, increase of lateral displacement and decrease of vertical stiffness according to nonlinear behavior of lead-rubber bearing (LRB) were evaluated. The displacement response, the acceleration response, and the shear force response of the seismically isolated nuclear containment structure were evaluated using the simple beam-stick model. It can be observed that the seismic responses of the isolated nuclear structure subjected to Gyeong-Ju earthquake is significantly less than those to the artificial earthquakes corresponding to NSDS.

This paper investigates seismic damage potential of recent September 12 M5.8 Gyeongju earthquake from diverse earthquake engineering perspectives using the accelerograms recorded at three stations near the epicenter. In time domain, strong motion durations are evaluated based on the accelerograms and compared with statistical averages of the ground motions with similar magnitude, epicentral distance and soil conditions, while Fourier analysis using FFT is performed to identify damaging frequency contents contained in the earthquake. Effective peak ground accelerations are evaluated from the calculated response spectra and compared with apparent peak ground accelerations and the design spectrum in KBC 2016. All these results are used to consistently explain the reason why most of seismic damage in the earthquake was concentrated on low-rise stiff buildings but not quite significant. In order to comparatively appraise the damage potential, the constant ductility spectrum constructed from the Gyeongju earthquake is compared with that of the well-known 1940 El Centro earthquake. Deconvolution analysis by using one accelerogram speculated to be recorded at a stiff soil site is also performed to estimate the soil profile conforming to the response spectrum characteristics. Finally, response history analysis for 39-and 61-story tall buildings is performed as a case study to explain significant building vibration felt on the upper floors of some tall buildings in Busan area during the Gyeongju earthquake. Seismic design and retrofit implications of M5.8 Gyeongju earthquake are summarized for further research efforts and improvements of relevant practice.

A significant number of Chinese and international earthquake disaster surveys indicate active faults as the root cause of earthquakes. Areas along fault lines experience the most severe damage and a greater number of personal injuries compared to regions on either side of the fault. Therefore, by adopting the shallow seismic reflection method to accurately detect the location and distribution of active faults, and developing effective measures to evade active faults, we can reduce earthquake disaster damage and economic losses. On April 20, 2013, the Lushan Ms7.0 earthquake occurred near the Shuangshi-Dachuan Fault (SDF) in the southern section of the Longmenshan fault zone. Because of its relatively high rate of earthquake activity, complex seismo-tectonic environment, and unique geological conditions, achieving usable data with seismic reflection is not easy. For that reason, available shallow seismic data of the SDF is extremely scarce. In our work, we carefully designed a survey to meet the constraints of the project and we have identified the precise location and near-surface structural form of the NE-trending SDF in the disaster area of the earthquake. The seismic surveys were located in Shuangshi Town of Lushan County and Daxi of Baoxing County. The detection of the SDF provided a scientific basis for selecting sites for post-disaster recovery and reconstruction to avoid these active fault zones, and reduce possible disastrous losses that could be caused by future earthquakes.

The accuracy of earthquake locations and their correspondence with subsurface geology depends strongly on the accuracy of the available seismic velocity model. Most modern methods to construct a velocity model for earthquake location are based on the inversion of passive source seismological data. Another approach is the integration of high-resolution geological and geophysical data to construct deterministic velocity models in which earthquake locations can be directly correlated to the geological structures. Such models have to be kinematically consistent with independent seismological data in order to provide precise hypocenter solutions. We present the Altotiberina (AT) seismic model, a three-dimensional velocity model for the Upper Tiber Valley region (Northern Apennines, Italy), constructed by combining 300 km of seismic reflection profiles, 6 deep boreholes (down to 5 km depth), detailed data from geological surveys and direct measurements of P- and S-wave velocities performed in situ and in laboratory. We assess the robustness of the AT seismic model by locating 11,713 earthquakes with a non-linear, global-search inversion method and comparing the probabilistic hypocenter solutions to those calculated in three previously published velocity models, constructed by inverting passive seismological data only. Our results demonstrate that the AT seismic model is able to provide higher-quality hypocenter locations than the previous velocity models. Earthquake locations are consistent with the subsurface geological structures and show a high degree of spatial correlation with specific lithostratigraphic units, suggesting a lithological control on the seismic activity evolution.

This paper deals with the dynamic response of a free-standing ancient column in the Roman Agora of Thessaloniki, Greece as a means to shed more light on the complex behaviour of rocking bodies under seismic excitation. Numerical analyses utilizing discrete element method were carried out with the use of multiple seismic records selected based on the disaggregation of the seismic hazard for the region of interest. To identify their impact on structural performance, earthquake Intensity Measures, such as Peak Ground Acceleration and Peak Ground Velocity are examined for the case of a column that sustained no visible permanent deformations during the Ms = 6.5 Thessaloniki earthquake of 1978. The analysis revealed a weak correlation of PGA and PGV with the response results and a significant influence of the mean frequency (fm) of the seismic motion. No coupling was found between the maximum displacement of the top during the oscillation and the permanent post-seismic deformations. The complementarity of both earthquake Intensity Measures in the structural vulnerability assessment is also depicted.

Metro underground tunnels are strategic elements in transportation and utility networks in any metropolitan city and their importance makes their vulnerability to earthquakes a very sensitive issue. A large earthquake would not only cause loss of human lives but can also damage lot of other pertinent infrastructure. In order to reduce the potential loss of serviceability, it is essential to reduce the possible risk associated and the effects of damage. Underground structures cannot be treated as completely exempt to the effects of ground shaking, as demonstrated by the recent Kobe earthquake of 1995, Chi–Chi earthquake of 1999, and Niigata earthquake of 2004, where several underground structures suffered severe damage. Earlier work in this area suggests that various authors have presented explicit expressions for axial force, shear force and bending moment developed in the RC liners of tunnels. Some numerical studies were also undertaken. In this paper, an attempt has been made to simulate the case of Delhi metro underground tunnels through PLAXIS 2D and study their response to 1991 Uttarkashi earthquake of lower Himalaya and then conduct some parametric study. The response so obtained has been compared with the available closed form solutions. Damping plays a significant role in seismic analysis. Analysis shows that forces in RC liners reduce with increase in damping. Similarly, displacements, both in soil and RC liners, decrease with increase in damping. Amplification in horizontal acceleration occurs due to reduction in damping ratio. The effect of horizontal component of 1991 Uttarkashi earthquake was found to be more critical than the vertical component, though of course the influence of vertical component was also found to be significant. It has therefore been realized that seismic response of metro underground tunnels to the both horizontal as well as vertical component of earthquake should be considered in design.

The 7.8 Mw Gorkha earthquake struck the east of Lamjung in Nepal, followed by a sequence of powerful aftershocks. Chinese Team Six including the authors inspected the seismic damage to civil structures along 10 paths in densely populated areas with a seismic intensity of VII to IX, 40 days after the main shock. The damage was categorized according to structure types and described in detail. Several conclusions are made: powerful aftershocks can significantly affect the failure patterns; geological conditions, structure types, and height have great influence on the level of damage; and the local risky retrofitting technique needs improvement badly.

In highway projects, the common destruction effects of earthquake faults include the sand seismic liquefaction, the instability and failure of slopes. Thereinto, the dynamic instability of slopes induced by earthquake faults is most commonly seen. In order to research the influences of the destruction effects of earthquake faults on the dynamic stability of highway slopes, the distribution of previous earthquakes happening in the research area is qualitatively analyzed to establish the earthquake fault model and explore the kinematic characteristics. On this basis, representative slopes–cutting slopes in seismic damage areas are selected to calculate their earthquake response using the ABAQUS finite element program. The displacement field and acceleration output from the program are used to analyze the variation in the displacement of slope top and calculate the distribution coefficient of acceleration. Then, the stress fields output by the dynamic finite element analysis (FEA) are substituted in the genetic algorithm programmed by MATLAB to obtain the time history curves of safety factor of slopes and intelligently search the critical slip surfaces. By doing so, the changing rule of safety factor with seismic acceleration is obtained, together with the range of the safety factor of the envelope diagram of critical slip surfaces.

Pattern informatics (PI), load/unload response ratio (LURR), state vector (SV), and accelerating moment release (AMR) are four previously unrelated subjects, which are sensitive, in varying ways, to the earthquake’s source. Previous studies have indicated that the spatial extent of the stress perturbation caused by an earthquake scales with the moment of the event, allowing us to combine these methods for seismic hazard evaluation. The longrange earthquake forecasting method PI is applied to search for the seismic hotspots and identify the areas where large earthquake could be expected. And the LURR and SV methods are adopted to assess short-to-intermediate-term seismic potential in each of the critical regions derived from the PI hotspots, while the AMR method is used to provide us with asymptotic estimates of time and magnitude of the potential earthquakes. This new approach, by combining the LURR, SV and AMR methods with the choice of identified area of PI hotspots, is devised to augment current techniques for seismic hazard estimation. Using the approach, we tested the strong earthquakes occurred in Yunnan–Sichuan region, China between January 1, 2013 and December 31, 2014. We found that most of the large earthquakes, especially the earthquakes with magnitude greater than 6.0 occurred in the seismic hazard regions predicted. Similar results have been obtained in the prediction of annual earthquake tendency in Chinese mainland in 2014 and 2015. The studies evidenced that the ensemble approach could be a useful tool to detect short-to-intermediate-term precursory information of future large earthquakes.

This study investigates ground motion parameters and their damage potential for building type structures. It focuses on low and mid-rise reinforced concrete buildings that are important portion of the existing building stock under seismic risk in many countries. Correlations of 19 parameters of 466 earthquake records with nonlinear displacement demands of 1056 Single Degree of Freedom (SDOF) systems are investigated. Properties of SDOF systems are established to represent RC building construction practice. The correlation of damage and ground motion characteristics is examined with respect to number of story and site classes. Equations for average nonlinear displacement demands of considered RC buildings are given for some of the ground motion parameters. Velocity related parameters are generally found to have better results than the acceleration, displacement and frequency related ones. Correlation of the parameters may be expected to decrease with increasing intensity of seismic event. Velocity Spectrum Intensity and Peak Ground Velocity have been found to have the highest correlation values for almost all site classes and number of story groups. Common parameter of Peak Ground Acceleration has lower correlation with damage when compared to them and some other parameters like Effective Design Acceleration and Characteristic Intensity. © 2016 Techno-Press, Ltd.

Seismic catalogues summarize information mainly on recent earthquakes and seismic events, recorded by means of relatively new instruments. Hence, this information, although being of high quality and quantitative value, sometimes is rather incomplete, since historical earthquakes are neglected in many cases. An example is the 1908 Cerbon earthquake (in Spain). This shake caused a good number of effects in the epicentre and surrounding area, triggering a huge landslide among some other effects. A complete geological and seismic site analysis, accompanied by a historical review of testimonies and journals of the time describing this particular earthquake, has been carried out, along with a deep field investigation to identify the mechanism of this landslide and the characteristics of the involved materials. A retrospective pseudo-static numerical simulation has been carried out to calculate the most probable range of peak horizontal accelerations during the earthquake. The results demonstrate the moderate relevance of this shake, also allowing us to quantify its objective importance. The presented methodology can be easily extended to some other similar cases, if seismic catalogues are to be completed for future designs accounting for seismic considerations.

Geophysical characterization of the subsurface by shallow seismic and electrical resistivity in conjunction with the geological conditions can provide more realistic information on earthquake hazard vulnerability assessment. Earthquake hazard vulnerability assessment requires not only the knowledge of earthquake source and propagation of seismic waves, but also local geological conditions which regulate ground shaking. Geophysical methods such as shallow seismic, electrical tomography, borehole geophysics and microtremor response are the most effective tools those contribute substantially in the earthquake hazard microzoning program. Strong-motion ground shaking character of a site due to an earthquake depends firstly on the magnitude of the source (moment magnitude, Mw) and the focal depth. However, fault reactivation can develop strong ground shaking at a site. Similarly, ground liquefaction can occur due to wave attenuation and amplification and can develop long residence time for ground shaking. Hence, earthquake hazard vulnerability of a site can be addressed more realistically taking into consideration of the source response, path response and site response. Groundwater condition and lithological variation of the subsurface zone can play an important role on the seismic response of a site. Geophysical parameters such as electrical resistivity, shear-wave velocity, dominant period and amplification factor in conjunction with geological information provide earthquake hazard vulnerability status. Earthquake hazard zoning is the first and the most important required step toward seismic risk analysis and mitigation strategy in the densely populated urban areas. Major earthquakes such as Bengal Earthquake in 1885 (also known as Manikganj Earthquake), 1897 Great Indian Earthquake and 1918 Srimangal Earthquake affected Dhaka Mega City of Bangladesh significantly. These earthquakes have been considered as the scenario earthquakes for hazard vulnerability assessment of Dhaka Mega City.

A moderate earthquake ground motion with moment magnitude (Mw) 6.4 took place in the North-Western area of Iran on August 11, 2012, which was followed by an aftershock (Mw = 4.9) just 6 min later. Eleven minutes after the first event, the affected area was struck by another moderate seismic event (Mw = 6.3) coming from a different seismogenic source. Earthquake ground motions of this special type of seismic sequence were recorded in the cities of Varzaghan and Ahar. Therefore, the first part of this study investigated the energy distribution and frequency content characteristics of the Varzaghan–Ahar earthquake ground motions records through wavelet transform analysis. The second part of this study presents the results of the nonlinear response of SDOF systems subjected to as-recorded Varzaghan–Ahar seismic sequences. The nonlinear response was measured in terms of constant-ductility strength reduction factors, R , and inelastic displacement ratios, IDR, which were compared with predictive capabilities of previously proposed predictive expressions that take into account seismic sequences. Results indicate that the predictive expressions for R and IDR underestimate values obtained in this study for the intermediate- and long-period spectral region.

Earthquake could cause severe damage to the architectural heritage which should be conserved. The ground shaking by earthquake generates the dynamic loading to the structure on the surface and this dynamic loading can cause damage (such as collapse) to the structure. The magnitude of this dynamic loading is proportional to that of ground shaking. Therefore, seismic hazard can be determined through the evaluation of ground shaking. In this study, seismic hazard of architectural heritages in Seoul is evaluated by site investigation using surface wave method and site-specific ground response analysis.

In present work, seismic hazard from future earthquake is worked out for Delhi region in terms of different strong motion parameters such as peak ground acceleration (PGA), characteristics frequency and spectral acceleration (Sa). The earthquake of March 5, 2012, is taken as key earthquake for synthesis. Stochastic finite modeling technique based on dynamic corner frequency initially is used to produce and match the ground motion histories where 2012 earthquake was recorded. The matching is attained in terms of PGA, response spectra and duration. Once a good match is found, the ground motion is estimated for higher magnitude earthquakes (i.e., Mw 6.0 and Mw 6.5). Our work demonstrates that a Mw 6.0 magnitude earthquake in proximity of Delhi will deliver PGA estimations of 20–209 gal (1 cm/s2 = 1 gal), the lower values occurring at hard rock sites like NDI (IMD) and DJB. Similarly Mw 6.5 earthquake may produce PGA values ranging between 30 and 323 gal. Finally seismic hazard in Delhi and surrounding regions is estimated from Mw 6.5 magnitude earthquake in terms of PGA, Sa and predominant period. Our computation specifies that at short period, the small structures toward eastern and north-western part of Delhi city may be affected by the earthquakes. For a case of 0.5 s period, Sa values are distributed uniformly at all the places in Delhi, indicating that the buildings with five floors or so may be in danger from future higher magnitude earthquakes. The Sa maps acquired in this study can be utilized to survey the seismic danger of the region and identify vulnerably susceptible areas in and around Delhi from future higher magnitude earthquake.

Wind energy is a rapidly growing field of renewable energy, and as such, intensive scientific and societal interest has been already attracted. Research on wind turbine structures has been mostly focused on the structural analysis, design and/or assessment of wind turbines mainly against normal (environmental) exposures while, so far, only marginal attention has been spent on considering extreme natural hazards that threat the reliability of the lifetime-oriented wind turbine's performance. Especially, recent installations of numerous wind turbines in earthquake prone areas worldwide (e.g., China, USA, India, Southern Europe and East Asia) highlight the necessity for thorough consideration of the seismic implications on these energy harnessing systems. Along these lines, this state-of-the-art paper presents a comparative survey of the published research relevant to the seismic analysis, design and assessment of wind turbines. Based on numerical simulation, either deterministic or probabilistic approaches are reviewed, because they have been adopted to investigate the sensitivity of wind turbines' structural capacity and reliability in earthquake-induced loading. The relevance of seismic hazard for wind turbines is further enlightened by available experimental studies, being also comprehensively reported through this paper. The main contribution of the study presented herein is to identify the key factors for wind turbines' seismic performance, while important milestones for ongoing and future advancement are emphasized. Copyright © 2016 John Wiley & Sons, Ltd.

The variometric approach is investigated to measure real-time seismic waves induced by the 2015 Mw 7.8 Nepal earthquake with high-rate multi-GNSS observations, especially with the contribution of newly available BDS. The velocity estimation using GPS + BDS shows an additional improvement of around 20% with respect to GPS-only solutions. We also reconstruct displacements by integrating GNSS-derived velocities after a linear trend removal (IGV). The displacement waveforms with accuracy of better than 5 cm are derived when postprocessed GPS precise point positioning results are used as ground truth, even if those stations have strong ground motions and static offsets of up to 1–2 m. GNSS-derived velocity and displacement waveforms with the variometric approach are in good agreement with results from strong motion data. We therefore conclude that it is feasible to capture real-time seismic waves with multi-GNSS observations using the IGV-enhanced variometric approach, which has critical implications for earthquake early warning, tsunami forecasting, and rapid hazard assessment.

Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in companion paper and the latter in this paper. In order to investigate the effect of an input earthquake motion on the permanent deformation, three bins of spectral matched real earthquake records with different magnitude, regions, epicentral distance are constructed. Parametric study was performed using the verified RHA through the companion paper for each earthquake records in the bins. The most influential parameter affecting permanent displacement is magnitude. The other parameters describing earthquake motion are not significant enough to increase permanent displacement of the inverted T-type wall except for energy related parameters(AI, CI, SEI).

Fragility curves constitute the cornerstone in seismic risk evaluations and performance-based earthquake engineering. They describe the probability of a structure to experience a certain damage level for a given earthquake intensity measure, providing a relationship between seismic hazard and vulnerability. In this paper a numerical approach is applied to derive fragility curves for tunnel shafts built in clays, a component that is found in several critical infrastructure such as urban metro networks, airport facilities or water and waste water projects. The seismic response of a representative tunnel shaft is assessed using tridimensional finite difference non-linear analyses carried out with the program FLAC3D, under increasing levels of seismic intensity. A hysteretic model is used to simulate the soil non-linear behavior during the seismic event. The effect of soil conditions and ground motion characteristics on the soil-structure system response is accounted for in the analyses. The damage is defined based on the exceedance of the concrete wall shaft capacity due to the developed seismic forces. The fragility curves are estimated in terms of peak ground acceleration at a rock or stiff soil outcrop, based on the evolution of damage with increasing earthquake intensity. The proposed fragility models allows the characterization of the seismic risk of a representative tunnel shaft typology and soil conditions considering the associated uncertainties, and partially fill the gap of data required in performing a risk analysis assessment of tunnels shafts.