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In regions that undergo low deformation rates, as is the case for metropolitan France (i.e. the part of France in Europe), the use of historical seismicity, in addition to instrumental data, is necessary when dealing with seismic hazard assessment. This paper presents the strategy adopted to develop a parametric earthquake catalogue using moment magnitude Mw, as the reference magnitude scale to cover both instrumental and historical periods for metropolitan France. Work performed within the framework of the SiHex (SIsmicité de l’HEXagone) (Cara et al. Bull Soc Géol Fr 186:3-19, 2015. doi:10.2113/qssqfbull.186.1.3) and SIGMA (SeIsmic Ground Motion Assessment; EDF-CEA-AREVA-ENEL) projects, respectively on instrumental and historical earthquakes, have been combined to produce the French seismic CATalogue, version 2017 (FCAT-17). The SiHex catalogue is composed of ~40,000 natural earthquakes, for which the hypocentral location and Mw magnitude are given. In the frame of the SIGMA research program, an integrated study has been realized on historical seismicity from intensity prediction equations (IPE) calibration in Mw detailed in Baumont et al. (submitted) companion paper to their application to earthquakes of the SISFRANCE macroseismic database (BRGM, EDF, IRSN), through a dedicated strategy developed by Traversa et al. (Bull Earthq Eng, 2017. doi:10.1007/s10518-017-0178-7) companion paper, to compute their Mw magnitude and depth. Macroseismic data and epicentral location and intensity used both in IPE calibration and inversion process, are those of SISFRANCE without any revision. The inversion process allows the main macroseismic field specificities reported by SISFRANCE to be taken into account with an exploration tree approach. It also allows capturing the epistemic uncertainties associated with macroseismic data and to IPEs selection. For events that exhibit a poorly constrained macroseismic field (mainly old, cross border or off-shore earthquakes), joint inversion of Mw and depth is not possible, and depth needs to be fixed to calculate Mw. Regional a priori depths have been defined for this purpose based on analysis of earthquakes with a well constrained macroseismic field where joint inversion of Mw and depth is possible. As a result, 27% of SISFRANCE earthquake seismological parameters have been jointly inverted and for the other 73% Mw has been calculated assuming a priori depths. The FCAT-17 catalogue is composed of the SIGMA historical parametric catalogue (magnitude range between 3.5 up to 7.0), covering from AD463 to 1965, and of the SiHex instrumental one, extending from 1965 to 2009. Historical part of the catalogue results from an automatic inversion of SISFRANCE data. A quality index is estimated for each historical earthquake according to the way the events are processed. All magnitudes are given in Mw which makes this catalogue directly usable as an input for probabilistic or deterministic seismic hazard studies. Uncertainties on magnitudes and depths are provided for historical earthquakes following calculation scheme presented in Traversa et al. (2017). Uncertainties on magnitudes for instrumental events are from Cara et al. (J Seismol 21:551-565, 2017. doi:10.1007/s10950-016-9617-1). [ABSTRACT FROM AUTHOR]

The estimation of the seismological parameters of historical earthquakes is a key step when performing seismic hazard assessment in moderate seismicity regions as France. We propose an original method to assess magnitude and depth of historical earthquakes using intensity data points. A flowchart based on an exploration tree (ET) approach allows to apply a consistent methodology to all the different configurations of the earthquake macroseismic field and to explore the inherent uncertainties. The method is applied to French test case historical earthquakes, using the SisFrance (BRGM, IRSN, EDF) macroseismic database and the intensity prediction equations (IPEs) calibrated in the companion paper (Baumont et al. Bull Earthq Eng, 2017). A weighted least square scheme allowing for the joint inversion of magnitude and depth is applied to earthquakes that exhibit a decay of intensity with distance. Two cases are distinguished: (1) a “Complete ET” is applied to earthquakes located within the metropolitan territory, while (2) a “Simplified ET” is applied to both, offshore and cross border events, lacking information at short distances but disposing of reliable data at large ones. Finally, a priori-depth-based magnitude computation is applied to ancient or poorly documented events, only described by single/sporadic intensity data or few macroseismic testimonies. Specific processing of “felt” testimonies allows exploiting this complementary information for poorly described earthquakes. Uncertainties associated to magnitude and depth estimates result from both, full propagation of uncertainties related to the original macroseismic information and the epistemic uncertainty related to the IPEs selection procedure. [ABSTRACT FROM AUTHOR]

The accurate evaluation and appropriate treatment of uncertainties is of primary importance in modern probabilistic seismic hazard assessment (PSHA). One of the objectives of the SIGMA project was to establish a framework to improve knowledge and data on two target regions characterized by low-to-moderate seismic activity. In this paper, for South-Eastern France, we present the final PSHA performed within the SIGMA project. A new earthquake catalogue for France covering instrumental and historical periods was used for the calculation of the magnitude-frequency distributions. The hazard model incorporates area sources, smoothed seismicity and a 3D faults model. A set of recently developed ground motion prediction equations (GMPEs) from global and regional data, evaluated as adequately representing the ground motion characteristics in the region, was used to calculate the hazard. The magnitude-frequency distributions, maximum magnitude, faults slip rate and style-of-faulting are considered as additional source of epistemic uncertainties. The hazard results for generic rock condition (Vs30 = 800 m/s) are displayed for 20 sites in terms of uniform hazard spectra at two return periods (475 years and 10,000 years). The contributions of the epistemic uncertainties in the ground motion characterizations and in the seismic source characterization to the total hazard uncertainties are analyzed. Finally, we compare the results with existing models developed at national scale in the framework of the first generation of models supporting the Eurocode 8 enforcement, (MEDD 2002 and AFPS06) and at the European scale (within the SHARE project), highlighting significant discrepancies at short return periods. [ABSTRACT FROM AUTHOR]

Up to now, the search for increased reliability in probabilistic seismic hazard analysis (PSHA) has concentrated on ways of assessing expert opinion and subjective judgement. Although in some areas of PSHA subjective opinion is unavoidable, there is a danger that assessment procedures and review methods contribute further subjective judgements on top of those already elicited. It is helpful to find techniques for objectively assessing seismic source models that show what the interpretations physically mean in terms of seismicity. Experience shows that well-meaning but flawed design decisions can lead to source models that are incompatible with the seismic history that was used as input. In this paper a method is demonstrated in which large numbers of synthetic earthquake catalogues, that match the completeness thresholds of the historical catalogue, are generated. The study area can be divided into a grid of uniform cells, and the number of earthquakes in each cell in both the historical catalogue and each simulated catalogue are then counted. Comparison of the historical pattern and a set of 1,000 simulated patterns, using a X test, shows if the historical pattern is credibly a member of the set of outcomes obtainable from the seismic source model. A second method is to chart the distribution of a large sample of simulated catalogues in terms of magnitude frequency, and observe whether the historical catalogue is comfortably within this distribution, or an outlier. If it proves impossible to replicate the historical catalogue using the model, it casts doubt on whether the model is a valid depiction of the seismicity rates that will govern the future hazard. At the very least, the disparity needs careful investigation to ensure the model is error-free. A worked example is presented here for the UK, using a source model that was used in Global Seismic Hazard Map (GSHAP), compared to one that was artificially constructed to be credible but flawed. Two tests find the GSHAP model to be an acceptable representation of the pattern of seismicity in the UK, while the artificial model is conclusively rejected. [ABSTRACT FROM AUTHOR]

Earthquake-induced slope instability is one of the major sources of earthquake hazards in near fault regions. Simplified tools such as Newmark's sliding block (NSB) analysis are widely used to estimate the sliding displacement of slopes during earthquake shaking. Additionally, empirical models for predicting NSB displacement using single or multiple ground motion intensity measures based on global (e.g. NGA-W1 database, Chiou et al. 2008) or regional datasets are available. The objective of this study is to evaluate the compatibility of candidate NSB displacement prediction models for the probabilistic seismic hazard assessment (PSHA) applications in Turkey using a comprehensive dataset of ground motions recorded during the earthquakes occurred in Turkey. Then, application of the most suitable NSB displacement prediction model in the vector-valued PSHA framework is demonstrated using the seismic source characterization models developed for Bolu-Gerede Region (in northwest Turkey). The results are presented in terms of the NSB displacement hazard curves and the hazard curves are evaluated for the influence of parameter selection (site conditions, yield acceleration, distance to the fault plane, and other seismic source model parameters) on the final hazard output. [ABSTRACT FROM AUTHOR]

The article presents a comparison of different probabilistic methods for ground motion hazard assessments that include site effects. The approaches examined here were selected and refined during the different phases of the S2-Project, which this journal volume is addressed to. Different procedures characterized by different levels of sophistication, from the simpler one based on the use of standard ground motion predictive equations for specific ground types to the more complex one based on the convolution of a site-specific amplification function (and its variability) with the hazard curve for reference rock, are compared and contrasted with the aim of pointing out strengths and weaknesses of each of them. In addition, a fully non-ergodic approach that separates the epistemic contribution (i.e., the epistemic uncertainty affecting the soil properties) from the total variability in site amplification is presented. To fulfill the scope of the work, the study focuses on three test sites in Italy characterized by different geological conditions and seismicity levels: Mirandola and Soncino in the Po Plain (northern Italy) and Peglio in central Italy. [ABSTRACT FROM AUTHOR]

European researchers and seismic networks are active in developing new approaches to earthquake early warning (EEW), implementing and operating test EEW systems, and in some cases, offering operational EEW to end users. We present the key recent developments in EEW research in Europe, describe the networks and regions where EEW is currently in testing or development, and highlight the two systems in Turkey and Romania that currently provide operational systems to a limited set of end users. [ABSTRACT FROM AUTHOR]

An extensive application of seismic microzoning studies requires the definition of specific proxies to allow local practitioners to quantify litho-stratigraphical amplification phenomena on the basis of procedures simple enough to allow a widespread application. To be effective, these tools should be specialized to the litho-stratigraphical configurations representative of the study area. A procedure is here described for providing such a tool on the basis of extensive numerical simulations taking advantage of geological/geotechnical information made available by regional/national Authorities. This procedure is quite general and could be applied in several contexts and, in particular, in developing countries low seismicity areas or where extensive accelerometric databases are lacking. As an example, an application of the above procedure developed on behalf of the Tuscany Regional Administration (in Central Italy) is presented. [ABSTRACT FROM AUTHOR]