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On February 6th, 2023, southeastern Türkiye was shaken by two catastrophic earthquakes, close to northwestern Syrian border. The first earthquake (Pazarcık) occurred 45 km west of Gaziantep at 1:17:32 (UTC), with a shallow strike-slip faulting at a depth of approximately 8.6 km and a moment magnitude (M W) of around 7.7. The second event (Elbistan) took place 9 h later, 66 km north-east of Kahramanmaraş city center, also with shallow strike-slip faulting at a depth approximately 7 km and an M W of around 7.6. Turkish authorities reported a death toll of over 59,000 in Türkiye and about 8500 in Syria. The destructive effect of the earthquake resulted from widespread strong ground shaking, a rupture length exceeding 300 km, causing collapse of a large number of buildings. The catastrophic destruction of the built environment was accompanied by a range of other earthquake-related effects, including fault ruptures, landslides, and soil liquefaction. The aim of the study is to analyze the distribution of ground motion and their relationships with the observed damages for the two events. Spectral accelerations of key importance were assessed across a large area in the southeastern part of Türkiye. Notably, these accelerations were generally much higher than existing design spectra. A significant correlation between the observed concentration of damage and the significant amplification of motion induced by local soil conditions (such as soft soils and valley effects). The distinct tectonic structure of the region could be the main reason for the high amplification in the valleys (associated with basin effects), even at large distances from the epicenter, especially in correspondence with the bidimensional graben-type geological structures. The investigation delved into the analysis of four specific regions in detail: Antakya and Hassa (both in the Hatay province), Kahramanmaraş and Göksun. Notably, the observable valley effects were found to play a significant role and could account for the significant damage observed in these regions. • An accurate analysis was conducted to examine the distribution of ground motion for the Türkiye Mw 7.7 Pazarcık and Mw 7.6 Elbistan earthquakes of February 6th, 2023 for a large area in the southeastern part of Türkiye.. • The recorded accelerations were generally much higher than existing design spectra by explaining the extensive devastation in the affected areas. • The observed concentration of damage was found to correlate with the significant amplification of motion induced by local soil conditions, such as soft soils and valley effects. • Detailed studies on four case histories: Antakya, Hassa, Göksun, and Kahramanmaraş, were performed by cross-checking recorded ground motions and geological and geotechnical data. • The analyzed four cities: Antakya, Hassa, Göksun, and Kahramanmaraş settled on relatively thick alluviums bordered by mountainous rock flanks are susceptible to valley effects. [ABSTRACT FROM AUTHOR]

The performance of a Metallurgical Facility located on the Dörtyol-Hatay coast is investigated from seismic soil liquefaction engineering perspective. The facility was shaken by the M7.8, and M7.6 Pazarcık and Ekinözü-Elbistan Kahramanmaraş earthquake sequence. This paper presents the assessment results of soil liquefaction triggering and induced ground deformations at the site. It discusses: i) the seismic response of the facility, more specifically, the surface manifestation of seismic soil liquefaction in the form of soil ejecta, ground deformations and displacements, mapped after the earthquake sequence, ii) the results of site investigation studies, performed prior to the events, iii) subsurface soil characterization of the site, iv) assessments of soil liquefaction triggering, v) analyses of liquefaction-induced ground settlements, lateral deformations and displacements, and vi) comparisons of them with those of the predicted. The case history performance documented herein, and the assessment results are believed to be useful in the development of case history-based predictive models for the assessment of liquefaction triggering and post-liquefaction ground deformations. • Liquefaction manifestations observed in a Metallurgical Facility in Hatay. • Lateral displacements and settlements varied in the range of 5–31 cm and 5–88 cm. • Low plasticity silts and clays were predicted to be liquefied. • Volumetric settlements were predicted by Shamoto et al. (1998) and Cetin et al. (2009). • Lateral displacements were predicted by Hamada et al. (1986) and Youd et al. (2002). [ABSTRACT FROM AUTHOR]

The seismic response and isolation mechanism of a new unconnected pile-caisson foundation (UPCF) suitable for supporting deep-water large-span bridges under seismic loading were investigated by large shaking table tests. Five scaled models were constructed utilizing different cushion material (aggregate), cushion thickness and piles configuration. Each model was tested under 18 different seismic loading conditions. The tests observations were analyzed to evaluate the seismic response characteristics and isolation mechanism of UPCF. The maximum displacement of UPCF and the peak acceleration of the input ground motion were linearly related. Under strong ground motions, the foundation soil and cushion displayed a significant softening behavior manifested in reduced natural frequencies and prolonged periods, which resulted in lower acceleration amplification. However, the stiffnesses of soil and cushion were largely restored after the ground shaking ended. The cushion model with larger aggregate particles performed better in terms of the caisson residual displacement and displacement restoration rate of the caisson. It was found that the UPCF constructed with a thin cushion layer comprised of large, rounded aggregate particles exhibited acceptable seismic isolation effect and reduced the peak seismic acceleration by up to 26.7%. It was also observed that the front and middle piles experienced larger loads, and accordingly, their peak moment envelopes were greater and the location of peak moment was shallower. • The dynamic response of the unconnected piles-caisson foundation (UPCF) is obtained, by large-scale shaking table tests. • The influences of cushion material, thickness and pile arrangement on the isolation effect are evaluated. • It is observed that the softening effect of the cushion under strong earthquake motions. • The relationship between earthquake intensity and caisson peak displacement is obtained. [ABSTRACT FROM AUTHOR]

Abstract Several earthquakes over the past two decades have demonstrated that bridges crossing fault rupture zones may suffer significant damage due to the combined effects of ground shaking and surface rupture. Although it is widely recommended to avoid building a bridge across a fault, it is not always possible to achieve this objective, especially in regions with a dense network of active faults. This review begins by compiling two databases: one of fault-crossing bridges damaged in past earthquakes and another of bridges crossing potentially active fault rupture zones. The article then continues to review findings of experimental, analytical and numerical studies, and to summarize seismic design provisions and recommendations related to fault-crossing bridges. The review ends with suggestions for future research directions in this area. Highlights • Information about fault-crossing bridges damaged in past earthquakes is collected. • A database of well-documented cases of bridges crossing potentially active faults is compiled. • Small- and large-scale experimental studies of fault-crossing bridges are reviewed. • Analytical and numerical studies of bridges crossing fault rupture zones are summarized. • Seismic design provisions and recommendations for fault-crossing bridges are discussed. [ABSTRACT FROM AUTHOR]

An active sequence of earthquakes (foreshock, main-shock, and aftershocks) hit the Kumamoto area (Japan) in April 2016, resulting in 69 deaths and considerable economic loss. The earthquakes induced numerous ground failures and cascading geo-hazards, causing major damage to important infrastructures. The main damage patterns include: (a) surface rupture with widespread subsidence of the surface ground, resulting in damage and disruption to transport infrastructure; (b) landslide and slope failure of mountains causing severe damage, collapse and near-collapse of bridges; and (c) liquefaction in some areas of Kumamoto City. Following the earthquakes, field surveys were conducted to study the damages and to understand the main cause of the observed failures. This technical note provides a summary of the geotechnical and infrastructural damage in Kumamoto and the lessons learnt and future research needs are also highlighted. [ABSTRACT FROM AUTHOR]

Tectonic ground deformations in the near-fault region cause major damage to buildings and infrastructure. To characterize ground deformation demands on structures, a novel stochastic approach to evaluate the ground deformations of tectonic origin is developed by combining probabilistic models of earthquake source parameters, synthetic earthquake slip models, and Okada equations for calculating the deformation field due to a fault movement. The output of the method is the probability distribution of ground deformations at a single location or differential ground deformations between two locations. The derived probabilistic models can be employed as input to advanced structural models and analyses. The method is illustrated for the 16 April 2016 Kumamoto earthquake in Japan. By comparing simulated ground deformations with observed deformations at multiple sites, a set of refined source models is first derived and then used to investigate the detailed earthquake characteristics of the event and to develop probability distributions of tectonic ground deformations at target sites. [ABSTRACT FROM AUTHOR]

A new algorithm is proposed to implement viscoelastic wave propagation in earth medium with surface topography by introducing history variables into integral type GZB constitutive equations and by using the recursive formulae of these history variables. Combining the proposed algorithm with the flexural wave algorithm for frame structure and the algorithm for bidirectional wave propagation, a new type of integrated method is developed for earthquake response analyses of near-fault building clusters in mountain city due to rupture of causative fault. The earthquake responses of building clusters of frame structures situated at different sites of a mountain in Chongqing city, China, are studied during a hypothetical M w 6.2 near-fault earthquake. The numerical results show that, for the multi-story buildings, the maximum peak value of beam-end bending moments appears in the building on the hill top and the earthquake risk positions are mainly at the bottom and/or the top of the buildings. For the high-rise buildings, the maximum peak value of beam-end bending moments appears in the building on the mountainside and the earthquake risk positions are mainly at the bottom and/or the middle of the buildings. [ABSTRACT FROM AUTHOR]

The geology of SW-Iceland is characterized by alternating basaltic lava units, hyaloclastite formations, postglacial sedimentary filled valleys and alluvial plains, as well as highly fractured bedrock within the Reykjanes Peninsula volcanic rift zone and the South-Iceland transform fault system. Historic earthquakes within this region reach magnitudes 6.5–7. Using earthquake and ambient noise recordings from 15 seismic stations within the rift and transform zones we compared wavefield polarization and seismic site response in order to assess characteristics of local amplification of ground motion. Ambient noise and earthquake ground motion spectral ratios are comparable in frequency and can qualitatively be subdivided into three groups: one with a spectral ratio characterized by a single predominant frequency of horizontal amplification, one with a bi- or multimodal and one characterized by a relatively constant amplitude across the frequency range. Seismic wavefield polarization within the transform zone has a prevailing direction of amplification towards 110°−150°N in the frequency range 1.0–3.0 Hz, having a quasi -perpendicular relationship with mapped faults and fractures. Shear wave splitting results show that the wavefield polarization and fast S wave directions tend to be orthogonal, i.e. highly dependent on the anisotropy of the medium. [ABSTRACT FROM AUTHOR]

In this paper, seismic behavior of gas supply networks is investigated by constructing a 24 m×24 m buried network and conducting an artificial earthquake test by detonating TNT explosives. The pipe network consists of typical welded steel pipes used in gas supply networks. Ground motion is produced by detonating 30 kg of TNT explosives buried 5 m below ground surface and 15 m away from the network. The test preparations are presented, including site selection, network layout, ground motion generation, and arrangements of different sensors. The measured ground acceleration, strain, and acceleration of welded steel pipes, and pipe–soil relative slippage are discussed. The deformation patterns of welded steel pipes are also analyzed and explained, including axial and bending deformations, systematic network characteristics, deformation relationship between ground and pipes, and dynamic response of buried pipes. [ABSTRACT FROM AUTHOR]

This study discusses the effects of local site conditions on earthquake ground motion for city of Xanthi, North-Eastern Greece, focusing on the influence of complex site effects and soil non-linearity. Although city of Xanthi is characterized as a low seismicity area, documented strong earthquake events of past centuries indicate the necessity of an appropriate estimation of ground surface motion of the region. Therefore, a typical 2D cross-section along the city following an E-W direction is constructed, based on the synthesis of available geological, geotechnical and geophysical data of the broader area. 1D and 2D numerical models are generated utilizing the Finite Difference Method and site response is investigated for different seismic scenarios. Wave amplification is captured as a result of 1D resonance phenomena integrated with potential 2D complex wave effects, due to lateral propagation of the locally generated at the discontinuities surface waves. The additional, relatively to 1D, 2D amplification or de-amplification of ground shaking, in terms of its amplitude and its spectral content is quantified. The impact of soil deposits non-linearity on amplification level, as well as, on generated 2D wave fields is considered by implementing both equivalent-linear and non-linear approaches. The results reveal that, across the city, spatial variation of ground surface motion is obvious, attributed primarily to the variation of subsurface soil profiles. 2D wave effects have been generated signifying that, at particular site locations, ground motion is additionally amplified or de-amplified with respect to 1D response. However, 2D versus 1D differentiation has been calculated of ±20% in terms of PGA and spectral accelerations up to 1.0 s, in the majority of the examined sites, implying that site response even though, influenced by 2D resonance phenomena, could be sufficiently captured by an 1D approach. Moreover, it is shown that if soil non-linearity is properly accounted for, it may play an important role on the estimated ground response, since non-linear approach seems to produce lower amplification levels with regard to 1D and 2D equivalent-linear approaches. As a general trend across the investigated site, for the entity of the various scenarios, the numerically calculated response spectra exceed EC8 seismic code provisions. [ABSTRACT FROM AUTHOR]

In 2012 Northern Italy was hit by a seismic sequence with earthquakes of moderate local magnitudes and shallow hypocentral depths. After the main shocks of May 20, collapse of buildings and lifeline ruptures were widely observed in the epicentral area within a distance of about 15 km, where large acceleration values with prevailing vertical component were recorded. Locally, at a greater distance, intense and spectacular liquefaction effects were observed. They mainly affected the earthen embankments of the old Reno river channel (paleochannel), and, to a lesser extent, their immediate surroundings. In these far-field areas, ground surface accelerations were significantly low and not consistent with the spreading and extent of the observed liquefaction effects. A detailed geotechnical survey was performed to identify depth, location and behaviour of liquefied soil layers and to analyse their influence on ground response and surface liquefaction effects. Results from in situ and laboratory tests, performed under static and dynamic loading conditions, are presented herein and a complete geotechnical model of the ancient levees and the underlying soil deposit is proposed for numerical site-specific seismic analyses. More attention was paid to analysing the influence of non-linear behaviour of interbedded liquefied sands on the expected surface ground motion. Implications and limits of the results obtained are discussed with, finally, proposals for adjustments to 1-D linear equivalent models operating in the frequency domain, for taking into account stiffness degradation of liquefiable layers at high strain levels. [ABSTRACT FROM AUTHOR]

Surface fault rupture has caused significant damage to structures in several earthquakes. The propagation of the bedrock fault rupture through the overlying soil deposit has been studied by several researchers; however, the effects of fault rupture dynamics, as opposed to pseudostatic fault movement, have not yet been evaluated. There is the potential for dynamic effects to influence significantly structural damage due to the rapid rate of deformation imposed by surface fault rupture. Numerical simulations are performed to analyze the effects of the rate of fault rupture on dip-slip surface fault rupture for free-field and soil-structure interaction conditions. The numerical results indicate that in some limited scenarios, fault rupture dynamics can influence the amount of structural damage expected for a structure located near a fault. However, in most scenarios, fault rupture dynamics is expected to play a secondary role compared to fault, soil, and structural characteristics in evaluating building performance. [ABSTRACT FROM AUTHOR]

The discrepancies between the dynamic response obtained with "Beam on the nonlinear Winkler Foundation" method, as a 1D model, and the actual pile behaviour in the liquefiable ground have been identified and marked in the vast body of literature. In this study, a 1D formulation is presented for the soil-pile system which provided considerable insights on the physics of the soil behaviour around the pile in the liquefiable ground and its dependence on soil properties. Unlike the mechanical models that may or may not be generalizable, the presented method is controlled by the soil properties. By a concept that the pile response is mainly influenced by the response of soil located on a unit volume in the pile vicinity, a macro-element is hypothesized by introducing a volumetric constraint incorporating the soil volume changes. The nonlinearity of macro-element is coupled in between volumetric and distortional behaviours where an incremental plastic work is assumed. Hence a stiffness matrix operator is used, instead of a scalar value, to link the pile resistance components with displacement components. A hypo-elastic bounding surface model was developed in this framework to capture the complex mechanism of soil-pile interaction in the liquefiable ground and presents a very good accord with available field measurement and centrifuge study while the computational time reduces to a couple of minutes for an earthquake excitation. An application for the presented 1D modelling approach is presented by calculating the instantaneous period and damping of the soil-pile interaction system in the liquefiable ground. • A 1D formulation is presented for the soil-pile system in liquefiable ground. • a macro-element is hypothesized by introducing a volumetric constraint incorporating the soil volume changes. • The nonlinearity of macro-element is coupled in between volumetric and distortional behaviours. • A stiffness matrix is used in linking pile resistance to the displacement components. • Instantaneous first-mode period and damping of the soil-pile system were calculated. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the fault rupture zone traversing a seismically isolated bridge is investigated utilizing a finite element model of a section of the Bolu Viaduct and a set of synthetic broadband strong ground motions simulated for the Bolu Viaduct site due to the 1999 Duzce earthquake. Both the original and a potential retrofit seismic isolation system designs are considered in the analyses. The results show double isolation system demands when fault crossing is considered, as compared to the case where fault crossing is ignored. The pier drift demands, however, remain comparable in both cases. Furthermore, the location of fault crossing along the bridge length, as well as the fault orientation with respect to the bridge longitudinal direction are shown to influence substantially the response of the seismically isolated bridge. Isolation system permanent displacements are greatly influenced by the restoring force capability of the isolation system when fault crossing effects in the excitations are ignored. In the case of fault crossing, the permanent displacements of the isolation system are dominated by the substantial permanent tectonic displacement along the fault trace which is imposed upon the structure. The results of this study contribute to developing a better understanding of how seismically isolated bridges respond when traversed by fault rupture zones. The lack of analyses and design guidelines for bridges crossing faults in international standards renders this study a useful reference for the profession. [Copyright &y& Elsevier]

Abstract: Wave energy flow in shallow ground depth is calculated based on main shock records obtained at 30 vertical array sites throughout Japan during nine recent strong earthquakes (M J =6.4–8.0) by assuming vertical propagation of SH waves. It is generally found that upward energy tends to decrease considerably as it goes up from the base (about 100m deep) to the ground surface. Large energy is reflected at layer boundaries with clear impedance contrast and returns to deeper ground, so that only less than 10–30% of the upward energy at the base level arrives at the ground surface in most sites. Energy dissipation calculated from the upward and downward energies tends to increase with the increase of damping ratio of the ground back-calculated from the seismic records. It is also found that the upward energy at the base may roughly be estimated for engineering purposes using spherical energy radiation of the body wave despite strong effects of fault rupture/path mechanisms. [Copyright &y& Elsevier]

The 2020 M7.0 Samos earthquake had occurred on the north of Samos Island; however, structural damage was observed in İzmir-Bayraklı, which is located approximately 65 km away from the epicenter. Strong ground motions recorded in İzmir Bay showed unique site amplifications, mostly due to the interaction between the basin and deep alluvial deposit response. The objective of this study is to evaluate the predictive performance of current ground motion models (GMMs) for estimating the recorded strong motions, especially the recordings over or near the Bayraklı-Bornova basin. 66 strong motion stations from Turkey with rupture distance (R RUP) < 200 km are used in the residual analysis, considering the ambiguities in the magnitude and depth to the top of the rupture estimations. Event terms of the earthquake for tested GMMs are found to be small and lie within the expected scatter, except for T = 0.5–1.5 s spectral accelerations. Event-specific distance attenuation for R RUP <100 km is consistent with the median predictions of current GMMs; however, the distance scaling for 100 km