Earthquake-induced Ground Motion Research Articles

A Parametric Study on Composite G+8 Structure With Application of Damper on Different Locations Using Time History Analysis

Abstract: The world's population has been growing quite quickly in recent years. Major cities, in particular, have relatively dense populations, which has increased demand for new homes. Because there isn't enough land for new construction in the majority of the old cities, high-rise buildings are moving into mountainous areas. These days, there is more competition to build high rise buildings all over the world as a result of certain developed nations building extremely tall skyscrapers to demonstrate their power and technology to the rest of the world. Buildings on sloping terrain, however, have different structural configurations than those on level terrain, which causes them to vibrate more during earthquake-induced ground motions, resulting in higher displacements and shears. Increased floor displacement results in damage to the structural components, rendering the structure unusable or, in the worst situation, collapsing as a whole. Reducing the amount of seismic energy that enters slanted ground buildings is essential to preventing damage. This can be done by absorbing the majority of the vibrations that an earthquake produces. There are numerous ways to lessen a structure's seismic reaction, including base isolation, shear walls, bracings, dampers, and more. Because of their effectiveness and simplicity of usage, damping devices are particularly well-liked among these methods. The eight-storey building model with four distinct cases—bare frame, bare frame with damper on corners, bare frame with damper on Central Bay, and bare frame with damper on Alternate Bay—is taken into consideration in this research examination. For modeling, use ETABS 2016 Ultimate programme. Utilize time history analysis as well to investigate how earthquake loading affects structures

FE-aided Kalman Filter for nonlinear state estimation with unknown input

A Kalman Filter-Finite Element (KF-FE) framework for joint input-state estimation of nonlinear systems is proposed in the current study. The KF-FE framework has been developed aiming to estimate the nonlinear structural behavior induced by excessive loading such as earthquake-induced ground motions or strong waves, during which a limited number of responses can be measured. The proposed framework involves the use of a Bayesian recursive filter, namely the Kalman Filter, in conjunction with a nonlinear Finite Element (FE) model, which allows to update the state space model formulation at each time step. The proposed KF-FE framework builds its novelty for nonlinear systems on the basis of existing methods for online state estimation of linear systems. The application of such a framework can be suitable for nonlinear state estimation when only output measurements are available. A numerical testbed is adopted herein consisting of a 2D steel moment resisting frame structure subjected to earthquake ground motions. The KF-FE results from the nonlinear numerical analysis scheme indicate estimation performance of high accuracy for both global (e.g., nodal displacements and rotations) and local (moment-curvature relationships) demand parameters while the computational cost is kept low.

The Importance of Assessing the Geological Site Effects of Ancient Earthquakes from the Archaeoseismological Point of View

Earthquakes have and continue to, occur worldwide, though some places are affected more than others by earthquake-induced ground shaking and the same earthquake can cause more damage in one area than in nearby locations due to site-specific geological site conditions, also known as local site effects. Depending on the chronology of the earthquakes, various disciplines of seismology include instrumental and historical seismology, archaeoseismology, palaeoseismology and neotectonics, each focusing on using specific sources of information to evaluate recent or ancient earthquakes. Past earthquakes are investigated to expand the pre-instrumental and instrumental earthquake catalog and better evaluate a region’s seismic hazard. Archaeoseismology offers a way to achieve these goals because it links how ancient civilizations and their environment might have interacted and responded to past earthquake-induced ground motion and soil amplification. Hence, archaeoseismology explores pre-instrumental (past) earthquakes that might have affected sites of human occupation and their nearby settings, which have left their co-seismic marks in ancient manufactured constructions exhumed by archaeological excavations. However, archaeoseismological observations are often made on a limited epicentral area, poorly constrained dated earthquakes and occasionally on unclear evidence of earthquake damage. Archaeological excavations or field investigations often underestimate the critical role that an archaeological site’s ancient geological site conditions might have played in causing co-seismic structural damage to ancient anthropogenic structures. Nevertheless, the archaeological community might document and inaccurately diagnose structural damage by ancient earthquake shaking to structures and even estimate the size of past earthquakes giving little or no consideration to the role of geological site effects in addressing the causative earthquake. This mixture of factors frequently leads to imprecise estimates of the size of ancient earthquakes and unlikely earthquake environmental impacts, leaving unexplained the location and the moment magnitude of the causative earthquake. Hence, it is essential not to rely solely on earthquake intensities based on archaeologically documented co-seismic damage without assessing the nature of the observed structural damage and the contribution of the geological site effects. This paper explains the geological site effects concept to archaeologists unfamiliar with the notion. It clarifies its role in assessing ground shaking, soil amplification and earthquake intensity by past earthquakes and how and why the geological site effects can be estimated when a site is thought to have been struck by an earthquake. Hence, the geological site effects must be considered when archaeological excavations describe and interpret destruction layers. Conversely, engineers and seismologists dealing with seismic hazard risk assessment must pay close attention to archaeological investigations assessing earthquake intensities and locations based on field evidence of damage to structures attributed to past earthquakes, because the geological site effects might have been factored in inaccurately or not at all.

TUNNEL REACTION TO GROUND MOVEMENT USING A SIMPLIFIED MODEL

Purpose: the analysis is performed by modal superposition of the response of a simplified model containing connected bending and shear beams supported by Winkler-type springs.
 Objective: to present a simplified model using coupled Bernoulli and shear beams supported by Winkler-type springs for the systematic identification of tunnels subject to earthquake-induced ground motions. A model formulation is introduced and closed-form solutions for the modal characteristic equation and mode shape are derived.
 Research methods: the formulation of the model is introduced and closed-form solutions are derived for the equation of modal characteristic and mode shape. The latter are checked by the results of numerical models. A system identification algorithm is then presented, demonstrating its ability to recover the model parameters when the recorded acceleration time intervals along the tunnel are perturbed by noise and sensor locations change. The presented framework can be used for initial and simple recovery of tunnel response in the presence of monitoring data or for planning monitoring campaigns in newly constructed or existing tunnels.
 Main results: using a simple genetic algorithm and the proposed simplified model, it was shown that system identification can be performed for variable conditions. The model was tested for two different earthquakes of different frequencies, and the influence of the distribution of sensors along the length of the tunnel was also parametrically investigated. The test results were intentionally compromised by adding white Gaussian noise with a variance equal to that observed during ground motion. It was observed that for values ​​of α >3.0 (ie, when the effect of the shear beam is significant), the model parameters can be successfully recovered. Therefore, for such conditions, the proposed approach can be used to recover important tunnel dynamic properties (e.g., T1 or α) as well as soil-structure interaction by tracking kb changes after earthquakes. For values ​​< 3, a Bernoulli beam with a Winkler basis is a valid representation, while observing differences with a model involving a Pasternak basis are marginal.
 Scientific novelty: another approach to parametric system identification using simplified models. For tunnels, such models usually consist of beams on independent Winkler-type springs, including both numerical and analytical schemes. However, the seismic response of the continuum (i.e., soil) can be better modeled by including a transverse beam above the Winkler foundation, which allows interaction between individual springs, rather than using a single layer of independent springs. In geotechnical seismic resistance, a similar approach was used to assess the seismic response of pile foundations and retaining walls.
 Conclusions and practical challenge: different sensor distributions and reduced number of sensors did not lead to significant differences in the final results. This first shows that sensor position is not the dominant parameter for the case of five sensors along the length of the tunnel, fixed at both ends, and uniform soil conditions and other assumptions made in the paper. Further tests should be performed on real data and sensors to examine the impact of other aspects such as sensor noise.
 Key words: winkler springs, soil; soil; model; system identification algorithm is presented.

S-Wave Attenuation Variation and its Impact on Ground Motion Amplitudes During 2016–2017 Central Italy Earthquake Sequence

A very energetic seismic sequence struck the central Apennines, Italy, in 2016–2017, with a series of damaging earthquakes, three of them with moment magnitudes M ≥ 5.9, and five of them with M ≥ 5.0, occurred over a few months between 24 August 2016, and late 2017. Several studies explained the phenomenon of a cascading earthquake sequence with fluid movements that provoked the rupture of different parts of the fault segments at different times and locations (e.g., Miller, Nature, 2004, 427, 724–727; Gabrielli, Frontiers in Earth Science, section Structural Geology and Tectonics, 2022; Malagnini, Frontiers in Earth Science, section Solid Earth Geophysics, 2022). In this study, we investigated the variation of crustal S-wave attenuation in terms of the frequency-dependent quality factor Q(f) before and after the main events (including the Amatrice, Visso, and Norcia sub-sequences, hereafter, AVN, and periods before and after the AVN multi-mainshock sequence). The spectral characteristics of regional attenuation in the central Apennines, as well as of the earthquake sources of the AVN sequence, are derived through regression analysis using a large set of seismograms; Q(f) is modeled, together with the bilinear geometrical spreading, g(r), using a widely used tool, namely, random vibration theory, RVT (Cartwright and Longuet-Higgins, 1956). The primary objective of this effort was to examine how the variability of crustal anelastic attenuation would impact the earthquake-induced ground motions. The latter is quantified in terms of peak ground accelerations (PGAs), peak ground velocities (PGVs), and pseudo spectral accelerations (PSAs) at 0.3 and 2 s . Here, we showed that the main events of the AVN sequence strongly affect crustal S-wave attenuation, including its frequency dependence. However, the effects of 1/Q(f) fluctuations on earthquake-induced ground motions are small and have a negligible impact on the seismic hazard.

Exploring the performances of the vibrating barriers for the seismic protection of the Zoser pyramid

In this paper we aim to investigate the use of the Vibrating Barrier (ViBa) as a potential strategy to mitigate the effects of the seismic action on the Zoser Pyramid. The Vibrating Barrier is a structure buried in the soil that is able to absorb a significant portion of the dynamic energy arising from the ground motion. The working principle exploits the dynamic interaction among vibrating structures resting on a compliant semi-infinite space, namely the structure–soil–structure interaction. A reliable numerical simulation of the Zoser Pyramid and the surrounding soil undergoing stochastic ground motion excitations representing the seismicity in Saqqara is presented. Due to the unique structural form, the ViBa is herein optimized through an ad-hoc procedure to minimize a response strain energy spectral density used as a synthetic performance parameter. Various layouts of the ViBa have been considered and presented in the paper. The efficiency of the ViBa is assessed by numerical simulation of the finite element model of the ViBa-Soil-Pyramid system and by laboratory testing. Results from a pertinent Monte Carlo study show an evident reduction of the stresses in the Pyramid manifesting the feasibility of this novel strategy to protect historic structures from earthquake-induced ground motion. Experimental results on a 1:500 gelatine model of the pyramid and the surrounding area highlighted the efficiency and efficacy of the proposed approach.

Power spectral models of stationary earthquake-induced ground motion process considering site characteristics

In this article, several spectral models describing the stationary stochastic process of earthquake ground motion are explored and compared. The Hu-Zhou spectrum, which is regarded as an improved model of Kanai-Tajimi spectrum, is concerned specially. It is proved that the earthquake-induced ground acceleration process described by the Hu-Zhou spectrum is a twice filtered white noise process in essence, and two filters for modifying low-frequency components and moderate- and high-frequency components respectively are investigated. Total 1946 strong earthquake records in different sites are employed to determine the parameters of spectral models, including the Kanai-Tajimi spectrum, the Clough-Penzien spectrum and the Hu-Zhou spectrum. The results show that the Hu-Zhou spectrum fits well with the actual observed ground motions over the whole frequency range, it is not only distinct in physical meaning and concise in mathematical expression, but also reasonable in practice.

New insights into the relationship between seismic intensity measures and nonlinear structural response

This paper focuses on the probabilistic analysis of Intensity Measures (IMs) and Engineering Demand Parameters (EDPs) in the context of earthquake-induced ground motions. Several statistical properties, which are desirable in IMs when they are used to predict EDPs, have been analysed. Specifically, efficiency, sufficiency and steadfastness have been quantified for a set of IMs with respect to two EDPs: the maximum inter-storey drift ratio, MIDR, and the maximum floor acceleration, MFA. Steadfastness is a new statistical property proposed in this article, which is related to the ability of IMs to forecast EDPs for large building suites. In other words, this means that efficiency does not significantly vary when different types of buildings are simultanously considered in the statistical analyses. This property allows reducing the number of calculations when performing seismic risk estimations at urban level since, for instance, a large variety of fragility curves, representing specific building typologies, can be grouped together within a more generic one. The main sources of uncertainty involved in the calculation of the seismic risk have been considered in the analysis. To do so, the nonlinear dynamic responses of probabilistic multi-degree-of-freedom building models, subjected to a large data set of ground motion records, have been calculated. These models have been generated to simulate the dynamic behavior of reinforced concrete buildings whose number of stories vary from 3 to 13. 18 spectrum-, energy- and direct-accelerogram-based IMs have been considered herein. Then, from clouds of IM-EDP points, efficiency, sufficiency and steadfastness have been quantified. For MIDR, results show that IMs based on spectral velocity are more efficient and steadfast than the ones based on spectral acceleration; spectral velocity averaged in a range of periods, AvSv, has shown to be the most efficient IM with an adequate level of steadfastness. For MFA, spectral acceleration-based-IMs are more efficient than velocity-based ones. A comparison is also presented on the use of linear vs quadratic regression models, and their implications on the derivation of fragility functions. Concerning sufficiency, most of the 18 IMs analysed do not have this property. Nonetheless, multi-regression models have been employed to address this lack of sufficiency allowing to obtain a so-called ‘ideal’ IM.

Comparative Study, Design and Analysis of a G+12 Structure in Earthquake Zone in India

Seismic isolation is a technology that decouples a building structure from the damaging earthquake motion. It is a simple structural design approach to mitigate or reduce potential earthquake damage. In base-isolated structures, the seismic protection is obtained by shifting the natural period of the structure away from the range of the frequencies for which the maximum amplification effects of the ground motion are expected; thus, the seismic input energy is significantly reduced. At the same time, the reduction of the high deformations attained at the base of the structure is possible, thanks to the energy dissipation caused by the damping and the hysteretic properties of these devices, further improving the reduction of responses of the structures. Base isolation is also an attractive retrofitting strategy to improve the seismic performance of existing bridges and monumental historic building.  The method of base isolation was developed in an attempt to mitigate the effects of earthquakes on buildings during earthquakes and has been practically proven to be the one of the very effective methods in the past several decades.  Base isolation consists of the installation of support mechanism which decouples the structure from earthquake induced ground motions.  Base isolation allows to filter the input forcing functions and to avoid acceleration seismic forces on the structure.  If the structure is separated from the ground during an earthquake, the ground is moving but the structure experienced little movement. To minimize the transmission of potentially damaging earthquake ground motions into a structure is achieved by the introduction of flexibility at the base of the structure in the horizontal direction while at the same time introducing damping elements to restrict the amplitude or extent of the motion caused by the earthquake somewhat akin to shock absorbers. In recent years this relatively new technology has emerged as a practical and economic alternative to conventional seismic strengthening. This concept has received increasing academic and professional attention and is being applied to a wide range of civil engineering structures. To date there are several hundred buildings in Japan, New Zealand, United States, India which use seismic isolation principles and technology for their seismic design.

Accounting for directivity-induced pulse-like ground motions in building portfolio loss assessment

Earthquake-induced pulse-like ground motions are often observed in near-source conditions due to forward-directivity. Recent worldwide earthquakes have emphasised the severe damage potential of such pulse-like ground motions. This paper introduces a framework to quantify the impact of directivity-induced pulse-like ground motions on the direct economic losses of building portfolios. To this aim, a simulation-based probabilistic risk modelling framework is implemented for various synthetic building portfolios located either in the fault-parallel or fault-normal orientations with respect to a case-study strike–slip fault. Three low-to-mid-rise building typologies representative of distinct vulnerability classes in the Mediterranean region are considered: non-ductile moment-resisting reinforced concrete (RC) frames with masonry infills, mainly designed to only sustain gravity loads (i.e. pre-code frames); moment-resisting RC infilled frames designed considering seismic provisions for high ductility capacity (i.e. special-code frames); special-code steel moment-resisting frames. Monte Carlo-based probabilistic seismic hazard analysis is first performed, considering the relevant modifications to account for the pulse-occurrence probability and the resulting spectral amplification. Hazard curves for sites/buildings located at different distances from the fault are obtained, discussing the spatial distribution of the hazard amplification. A set of pulse-like ground motions and a set of one-to-one spectrally-equivalent ordinary records are used to perform non-linear dynamic analysis and derive fragility relationships for each considered building typology. A vulnerability model is finally built by combining the derived fragility relationships with a (building-level) damage-to-loss model. The results are presented in terms of intensity-based and expected annual loss for synthetic portfolios of different sizes and distribution of building types. It is shown that, for particularly short-period structures (e.g. infilled RC frames), the influence of near-source directivity can be reasonably neglected in the fragility derivation while kept in place in the hazard component. Overall, near-source directivity effects are significant when estimating losses of individual buildings or small portfolios located very close to a fault. Nevertheless, the impact of pulse-like ground motions on losses for larger portfolios can be considered minimal and can be neglected in most of the practical large-scale seismic risk assessment applications.

Reliability-based seismic evaluation of buried pipelines subjected to earthquake-induced transient ground motions

Reliability-based seismic evaluation of buried pipelines subjected to earthquake-induced transient ground motions

Ground motion amplification models for Japan using machine learning techniques

Earthquake-induced ground motions can be altered by various factors that are associated with the characteristics of earthquake sources, paths, and sites. Conventionally, regression approaches have been used to develop empirical prediction models for ground motion amplifications. We developed models for ground motion amplifications based on three machine learning techniques (i.e., random forest, gradient boosting, and artificial neural network) using the database of the records at the KiK-net stations in Japan. The proposed machine learning based models outperforms the regression based model. The random forest based model provides the best estimation of amplification factors. Average shear wave velocity and the depth of the borehole are the two factors that influence the amplification model the most. Maps of the amplification factors for all KiK-net stations under moderate and large earthquake scenarios are provided. The three machine learning technique based models are also provided for the forward prediction of other earthquake scenarios.

A numerical investigation of seismic performance for an RC frame with latticed concrete infill walls

Expansive polystyrene granule cement (EPSC) latticed concrete wall can be used as an infill wall. After the expanded polystyrene granule cement form has been demolished, the part that remains is a latticed concrete infill wall comprising lattice beams and columns whose cross section is circular with a diameter of 0.12 m. The horizontal and vertical rebar are arranged within the beams and columns. The dynamic responses of a full-scale single-story reinforced concrete (RC) frame with latticed concrete infill walls subjected to earthquake-induced ground motion are simulated using the nonlinear finite element ABAQUS software. This study aims to investigate the effects of different types of earthquakes on the structure and the acceleration responses of the structure. The results obtained indicate that the structure has excellent seismic behavior, although the structural responses vary between earthquakes. This research may help in promoting the design and application of RC frames with latticed concrete infill walls.

The Spectral Behavior of Ground Coseismic Motion in the Baikal Region: Effect of Seasonal Thawing–Freezing Cycles

Abstract —Reliable solution of theoretical and applied seismological problems requires the knowledge of natural factors that influence ground motion induced by earthquakes. The effect of seasonal freezing and thawing on the behavior of coseismic ground motion in the Baikal region has been studied using data on local geology, earthquake source parameters, seismogeology, and seismic risk zoning for East Siberia. East Siberia, including the highly seismic Baikal region, is located in a temperate and cold, sharply continental climate, with the mean annual air temperature locally falling below –10 ºC. In this respect, the knowledge of seasonal variations in the ground motion spectra in different seismic-climatic zones of the region is of special importance. We study the dynamic parameters of seismic signals and their variations caused by seasonal thawing and freezing of the ground, using calculated spectra of selected earthquakes that were recorded by 0.5–20 Hz digital seismic stations at a sampling interval (Δ) of 0.01 s. Spectral analysis was applied to three-component records of more than two hundred M = 2.8 (K = 9–14) earthquakes that occurred in the region for the past twenty years at distances from 32 to 280 km from the stations. The influence of seasonal temperature variations on the frequency responses of coseismic ground motion is discussed for the case of two seismic stations in zones of continuous and sporadic permafrost. The results are complemented by generalized data from other seismic stations located in different permafrost conditions within the Baikal region. The effect of seasonal freezing and thawing turns out to be the most prominent at frequencies above 5–6 Hz and depend on the properties and thermal state of soils beneath the stations. At the same time, they are more prominent in thawing than in freezing curves for any soil, including relatively solid bedrock. The spectral behavior of earthquake-induced ground motion is associated with variations in wave amplitudes, which correlate with seasonal temperature variations. The reported results have implications for geophysical prospecting, seismic-risk zoning, and prediction of shaking intensity of large earthquakes, which require due regard for local permafrost conditions.

Theoretical modeling of spatially varying ground motions under ice-seawater interface and earthquake analysis of cable-stay bridges

The ice-seawater interface has a significant effect on earthquake-induced ground motion. This paper proposed a new method of modeling spatially varying ground motion due to ice-seawater layer. The reflection function was derived to evaluate the effect of ice-seawater layer on earthquake ground motion. Moreover, the coherence function and site transfer function were used to calculate the loss of spatial coherent and the corresponding local effects, respectively. Furthermore, the effects of water saturation on ground motion was considered. Taking the above factors into consideration, the spatial variance of seismic ground motions in an area with an ice-seawater interface was synthesized. The ground motion was assumed to consist of SH and P-SV waves, which included horizontal out-of-plane SH wave, horizontal in-plane P-SV waves and vertical in-plane P-SV waves. By comparing simulated ground motions with different site conditions, we observed that the vertical in-plane motion at the seafloor was noticeably attenuated when an ice-seawater interface was present. At the same time, the soil layer greatly amplified the acceleration of out-of-plane and in-plane ground motions. In order to verify the ability of the above method for synthesizing seismic time history, a three-dimensional seismic analysis of a large span cable-stayed bridge was conducted. Three of such case studies were used to investigate the effect of the ice-seawater interface on the bridge. Analysis of the displacement and bending moment of the bridge deck and tower demonstrated that the ice-seawater interface had a great effect on the seismic response of the cable-stayed bridge. In particular, the maximum vertical deck displacement with the ice-seawater interface present was 74% of the case in which the interface was absent. Likewise, the maximum longitudinal displacement of the bridge tower with the interface present was 70% of the case in which the interface was absent.

An uncertain computational model for random vibration analysis of subsea pipelines subjected to spatially varying ground motions

Based on a nonparametric modelling approach, this paper presents a random vibration analysis of a subsea pipeline subjected to spatially varying ground motions. The earthquake-induced ground motions are modelled as nonstationary random processes and their spatial variations are considered. The modelling uncertainties of the subsea pipeline are taken into account using a random matrix theory, while the unilateral contact relationship between the pipeline and seabed is also considered. Thus, an uncertain computational model for the subsea pipeline subjected to a random earthquake is established, and the corresponding solutions are calculated using Monte Carlo simulation (MCS). In order to highlight the contribution of the unilateral contact effect to random responses of pipelines, comparative studies are performed between the unilateral and permanent contact models. In numerical examples, the possible convergence problems in the present computational model are firstly studied to determine the optimal numbers of reduced modes and MCS samples. Then influences of the randomness in the earthquake and modelling uncertainties in the pipeline are investigated qualitatively through three representative cases. The different propagations of randomness and modelling uncertainties in the unilateral and permanent models are also examined and discussed. It is concluded that the randomness of the earthquake and modelling uncertainties of the pipeline have significant influences on the statistical characteristics of earthquake responses of the pipeline.

System Identification of Tunnel Response to Ground Motion Considering a Simplified Model

This paper presents a simplified model using coupled Bernoulli and shear beams supported by Winkler-type springs for system identification of tunnels subjected to earthquake-induced ground motions. The model formulation is introduced and closed-form solutions to the modal characteristic equation and mode shapes are derived. The latter are verified against the results of numerical models. Then, the system identification algorithm is presented, showcasing its ability to recover model parameters when recorded acceleration time histories along the tunnel are compromised by noise and sensor locations are varied. The presented framework can be used to initially and, simply, recover tunnel response when monitoring data is available, or to plan for monitoring campaigns in newly constructed or existing tunnels.

Two-dimensional site seismic response analysis for a strategic building in Catania

This study is part of a more extensive research aimed to the seismic risk mitigation in Eastern Sicily. The earthquakes that occurred in Sicily in 1169, 1542, 1693, 1818, 1908 and more recently in 1990, testify the high level of seismic hazard in this region. It is well recognized that local seismic effects can exert a significant influence on the distribution of damage during earthquake. Traditionally, these effects are studied by means of simple one–dimensional (1-D) models of seismic wave propagation, which take only the influence of the stratigraphic profile and soil proprieties into to account for the site seismic response. It is known that the seismic response is strongly influenced by stratigraphic and topographic features that can reduce or amplify the earthquake induced ground motion depending on the soil stiffness and on the ground topography. This paper concerns the results of a two-dimensional (2-D) finite element analysis carried out to evaluate the response of the site where the National Institute of Geophysics and Volcanology (INGV) building is located in the town of Catania. The analysis, performed using as seismic input the accelerogram recorded in 1990 during the Santa Lucia earthquake, allowed to make some considerations about the expected accelerations at that the site and some comparison with the peak accelerations prescribed by Italian seismic code.

On-going challenges in physics-based ground motion prediction and insights from the 2010–2011 Canterbury and 2016 Kaikoura, New Zealand earthquakes

This paper presents on-going challenges in the present paradigm shift of earthquake-induced ground motion prediction from empirical to physics-based simulation methods. The 2010–2011 Canterbury and 2016 Kaikoura, New Zealand earthquakes are used to illustrate the predictive potential of the different methods. On-going efforts in simulation validation and theoretical developments are then presented, as well as the demands associated with the need for explicit consideration of modelling uncertainties. Finally, discussion is also given to the tools and databases needed for the efficient utilisation of simulated ground motions both in specific engineering projects as well as for near-real-time impact assessment.

Earthquake-induced settlement of a clay layer

A model for pore water pressure accumulation and settlement of saturated clay layer induced by uniform and irregular cyclic shear strains was developed by concerning the direction of cyclic shear strain. To apply this model to any kinds of clay, the effects of Atterberg's limits of cohesive clay on the cyclic shear-induced pore water pressure and the settlement were observed by using the strain-controlled cyclic simple shear test apparatus which can control the cyclic shear direction. In conclusion, the effects of Atterberg's limits of clay on the cyclic shear-induced pore water pressure accumulation and settlement were clarified by using the cumulative shear strain. Based on the experimental results, estimation methods for the pore water pressure accumulation and post-cyclic settlement of clay with a wide range of Atterberg's limits were developed. Furthermore, to apply the proposed methods to the earthquake-induced ground motions, a transformation procedure of irregular cyclic shears to the equivalent uniform ones including the effect of cyclic shear direction was developed and the practical applicability was confirmed.