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As space-based Earth observations are delivering a growing amount and variety of data, the potential of this information to better support disaster risk management is coming into increased scrutiny. Disaster risk management actions are commonly divided into the different steps of the disaster management cycle, which include: prevention, to minimize future losses; preparedness and crisis management, often focused on saving lives; and post-crisis management aiming at re-establishing services supporting human activities. Based on a literature review and examples of studies in the area of coastal, hydro-meteorological and geohazards, this review examines how space-based Earth observations have addressed the needs for information in the area of disaster risk management so far. We show that efforts have essentially focused on hazard assessments or supporting crisis management, whereas a number of needs still remain partly fulfilled for vulnerability and exposure mapping, as well as adaptation planning. A promising way forward to maximize the impact of Earth observations includes multi-risk approaches, which mutualize the collection of time-evolving vulnerability and exposure data across different hazards. Opportunities exist as programmes such as the Copernicus Sentinels are now delivering Earth observations of an unprecedented quality, quantity and repetitiveness, as well as initiatives from the disaster risk science communities such as the development of observatories. We argue that, as a complement to this, more systematic efforts to (1) build capacity and (2) evaluate where space-based Earth observations can support disaster risk management would be useful to maximize its societal benefits.

The paper describes the methodology proposed in the PERPETUATE Project (funded by the Seventh Framework Programme – Theme ENV.2009.3.2.1.1). The methodology proposed in PERPETUATE uses a displacement-based approach for the vulnerability evaluation and design of interventions. The use of safety verification in terms of displacement, rather than strength, orients to new strengthening techniques and helps in the comprehension of interaction between structural elements and unmovable artistic assets. The procedure is based on the following fundamental steps: definition of performance limit states, specific for the cultural heritage assets (considering both structural and artistic assets); evaluation of seismic hazard and soil-foundation interactions; construction knowledge (non-destructive testing, material parameters, structural identification); development of structural models for the seismic analysis of masonry structures and artistic assets and design of interventions; application and validation of the methodology to case studies. Two main scales are considered: the seismic risk assessment at territorial scale and at the scale of single historic building or artistic assets. The final aim of the project is to develop European Guidelines for evaluation and mitigation of seismic risk to cultural heritage assets.

This paper presents two numerical case studies of medium and strong motion events, namely Loma-Prieta 1989 and Hyogoken-Nambu (Kobe) 1995. These simulations were performed using CyberQuake model. The cyclic elastoplastic constitutive model is fully detailed in the companion paper. Through these case studies, we demonstrate the importance of using appropriate constitutive modelling when the part played by nonlinear phenomena is preponderant. The need to account for 3D kinematics (i.e. the three components of the input motion), is also demonstrated, even though a 1D geometry is considered, as the plastic coupling existing between components of motion during the earthquake, strongly affects the seismic soil response.

International audience; The assessment of historical elements at risk from earthquake loading presents a number of differences from the seismic evaluation of modern structures, for design or retrofitting purposes, which is covered by existing building codes, and for the development of fragility curves, procedures for which have been extensively developed in the past decade. This article briefly discusses: the hazard framework for historical assets, including a consideration of the appropriate return period to be used for such elements at risk; the intensity measures that could be used to describe earthquake shaking for the analysis of historical assets; and available approaches for their assessment. We then discuss various unique aspects of historical assets that mean the characterisation of earthquake loading must be different from that for modern structures. For example, historical buildings are often composed of heterogeneous materials (e.g. old masonry) and they are sometimes located where strong local site effects occur due to: steep topography (e.g. hilltops), basin effects or foundations built on the remains of previous structures. Standard seismic hazard assessment undertaken for modern structures and the majority of sites is generally not appropriate. Within the PERPETUATE project performance-based assessments, using nonlinear static and dynamic analyses for the evaluation of structural response of historical assets, were undertaken. The steps outlined in this article are important for input to these assessments.

International audience; The destructive 1999 Chi-Chi earthquake (Mw 7.5) was the largest inland earthquake in Taiwan in the 20th century. Several observations witness the non-linear seismic soil response in sediments during the earthquake. In fact, large settlements as well as evidence of liquefaction attested by sand boils and unusual wet ground surface were observed at some sites. In this paper, we present a seismic response simulation performed with CyberQuake software on a site located within the Chang-Hwa Coastal Industrial Park during the 1999 Chi-Chi earthquake in Taiwan. A non-linear multi-kinematic dynamic constitutive model is implemented in the software. Computed NS, EW and UP ground accelerations obtained with this model under undrained and two-phase assumptions, are in good agreement with the corresponding accelerations recorded at seismic station TCU117, either for peak location, amplitudes or frequency content. In these simulations, liquefaction occurs between depths 1.3 and 11.3m, which correspond to the observed range attested by in place penetration tests and other liquefaction analyses. Moreover, the computed shear wave velocity profile is very close to post-earthquake shear wave velocity profile derived from correlations with CPT and SPT data. Finally, it is shown that in non-linear computations, even though a 1D geometry is considered, it is necessary to take into account the three components of the input motion.

The general methodology presented in Chap. 2 of this book, has been conceived in order to be general enough to be adequate for each system. The purpose of this chapter is to decline this methodology to the specificity of each physical system considered: i.e., Buildings, Water Supply System, Waste Water Network, Electrical Power Network, Oil and Gas Network, Transportation Network, Health Care System and Harbours. Each system is described based on its structure and taxonomy, on the dependencies it shares with the other systems, on the available methods to describe its systemic vulnerability and, finally, on the existing indicators to evaluate its performance, but also its functionality according to the societal needs.

In the proposed element-free Galerkin method for deforming multiphase porous media, displacement of the porous-solid skeleton is modelled by standard finite elements while wetting and non-wetting fluid pore pressures are included as element-free nodes. The matrix formulation is derived from the variational formulation of the multiphase governing equations. The case of a domain with a material or field discontinuity is handled by using Lagrange multipliers. One- and two-dimensional applications are presented for which the results, compared with those obtained by either the closed-form solution standard finite-element approach or experimental tests, show the efficiency of the proposed technique. The necessity of taking air pore pressure into account for partially saturated soils is discussed: free surface capturing is analysed and the problem of its intersection with outer boundaries (so-called seepage surface) is studied. © 1998 John Wiley & Sons, Ltd.

In this paper, spectral impedance for absorbing boundaries using second-order paraxial approximation is presented for a linear elastic isotropic media. High-order derivatives then appear which yields to employ the diffuse element method for discretize the displacement field in the weak form.

The present chapter aims to present and review fragility curves for components of gas and oil system networks. These fragility functions need to be applicable to the specific European context and they should be available for a variety of network components such as buried pipelines, storage tanks and processing facilities (i.e. compression and reduction stations). Based on a literature review, it is found that the available fragility functions are mostly empirical and should be applied to the European context, given the current lack of data needed to validate potential analytical methods of vulnerability assessment. For buried pipelines, fragility relations are reviewed with respect to both wave propagation and ground failure. Existing fragility curves for storage tanks and processing facilities are also critically appraised, according to the modelling assumptions and the derivation techniques (e.g. fault-tree analysis, numerical simulation or empirical relation).

In Bobrowsky, P. (Ed) Encyclopedia of Natural hazards, Springer, Encyclopedia of Earth Science series

Amongst different existing techniques developed for absorbing boundaries in transient dynamic analysis, the paraxial approximation represents an elegant framework. This approach is extended to the case of saturated porous media, which is of vital interest in many earthquake engineering problems. With respect to the frequency content of the dynamic process, several formulations exist for modelling the two-phase behaviou of soil or rock materials. The existence of a shear wave and two dilatational waves, which are standard features of porous media, is verified for the adopted formulation. The paraxial approximation is presented in the case of the u – p Biot two-phase dynamic formulation, suitable for seismic analyses and implemented by using a finite element approach. The efficiency of these boundaries is further verified through same numerical examples.

This paper, along with its companion paper, presents the importance of the adequate soil behaviour model to simulate earthquake site response analysis. An elastoplastic model taking into account the elementary necessary plastic mechanisms such as progressive friction mobilization, Coulomb type failure, critical state and dilatancy/contractance flow rule, is used. However, one of the obstacles in the use of elastoplastic models in the everyday design processes for evaluation of the seismic soil response is the difficulty in identifying their parameters. In this paper, a methodology to identify a coherent set of parameters of the elastoplastic model for a given type of soil is presented. The strategy behind the decision making process proposed here is based on the use of minimum physical and easily measurable properties of the soil to directly provide or indirectly assess the required model parameters.

International audience; A specific approach is studied to couple two well-known numerical methods, a finite difference method (FDM) and a finite element method (FEM) for simulating regional seismic wave propagation to local site response. This coupling uses a technique of the “paraxial approximation” in order to input in the FEM the seismic wave generated in the FDM. The main advantage of this approach is to locally extract an area of interest where non-linear soil response or complex geometry is important from the regional wave propagation in a relatively simple medium. This result in taking advantage of both methods: the portability of the FDM and the flexibility of the FEM. This paper presents a theoretical framework of the paraxial approximation, through which the coupling is realized between the FDM and the FEM, and demonstrates some examples for the validation of the proposed coupling technique as well as its possible applications.

International audience; We analyze the ingredients required for deterministic wave propagation simulation in order to estimate more accurately ground motion in terms of amplitude, frequency content and duration. Building maps of expected ground motion before a catastrophic event for various scenarios may help design ways to mitigate impacts of ground vibrations as well as fast calibration of these maps once the event occurs. Reconstruction of 3D structures requires collection of information at two different scales: the regional one (a few tens of kilometres) and the local (a few tens of metres to hundreds of metres). Different techniques from permanent to temporary deployments of seismic stations and from active to passive source excitations together with other geophysical and geotechnical investigations will provide the necessary information. Characterisation of possible seismic sources is another challenge and requires careful seismotectonic analysis in the region of interest. Uncertainties may be large provided that one can reproduce wave propagation from these hypothetical spatially extended sources. Frequency content of these simulations is more limited by our knowledge of the medium than by computer resources. In fact, in order to perform such simulations, the geological structure has to be known within a resolution scale of one-tenth of the wavelength. Duration and amplitude are affected by the source mechanism and the mechanical properties of the underground structure. Variability in these ground motion estimations should be appreciated and key parameters identified. Designing approaches to calibrate these simulations with recorded data as well as necessary links with the probabilistic approach should be addressed in the future.

National audience; ABSTRACT. Earthquake shaking represents complex loading to the structure. It cannot be accurately characterized by a single parameter, e.g. peak ground acceleration. The goal of this work is to compare the role of various strong-motion parameters on the induced damage in the structure through numerical calculations. To this end, a robust structural model that can perform several dynamic calculations, with an acceptable cost, is required. The developed methodology is based on the use of structural elements with nonlinear behaviour of damage mechanics and plasticity type. The damage level of a typical reinforced concrete structure is evaluated by the use of nonlinear numerical calculations. The effect of numerous ground-motion parameters on the computed damage is analyzed and discussed. A set of weakly-correlated parameters are chosen that characterize different aspects of the shaking. Natural accelerograms were chosen based on a consideration of the magnitude-distance ranges of design earthquakes. It is expected that an increase from one to two or three groundmotion parameters would lead to a significant reduction in the scatter in the fragility curve, which when more than one parameter is used will be a surface. RÉSUMÉ. Le mouvement sismique applique un chargement complexe aux structures. Un seul paramètre, e.g. " PGA ", ne peut pas caractériser correctement ce chargement. L'objectif de ce travail est d'évaluer le rôle de plusieurs paramètres caractérisant un séisme sur le niveau de dégradation des structures. Pour y parvenir, il est essentiel de disposer de modèles fiables et robustes nous permettant de réaliser plusieurs calculs de structures avec un coût limité. La méthodologie développée s'appuie sur l'emploi d'éléments de structure capables de tirer profit des lois de comportement non-linéaires de type mécanique de l'endommagement et plasticité. Les simulations sont réalisées à l'aide d'accélérogrammes naturels ayant des caractéristiques variées et imposées suivant les trois directions de l'espace. Ces études permettent d'estimer les niveaux d'endommagement des structures en béton armé pour différentes intensités de l'action sismique. Lors des simulations E.F. réalisées sur un modèle d'un bâtiment R+7 les effets de plusieurs paramètres du mouvement sismique sur l'endommagement ont été analysés. Grâce à deux ou trois paramètres caractérisant l'action sismique, nous espérons diminuer significativement la dispersion des résultats des études de vulnérabilité sismique du bâti.