The 2013 European Seismic Hazard Model (ESHM13) results from a community-based probabilistic seismic hazard assessment supported by the EU-FP7 project “Seismic Hazard Harmonization in Europe” (SHARE, 2009–2013). The ESHM13 is a consistent seismic hazard model for Europe and Turkey which overcomes the limitation of national borders and includes a through quantification of the uncertainties. It is the first completed regional effort contributing to the “Global Earthquake Model” initiative. It might serve as a reference model for various applications, from earthquake preparedness to earthquake risk mitigation strategies, including the update of the European seismic regulations for building design (Eurocode 8), and thus it is useful for future safety assessment and improvement of private and public buildings. Although its results constitute a reference for Europe, they do not replace the existing national design regulations that are in place for seismic design and construction of buildings. The ESHM13 represents a significant improvement compared to previous efforts as it is based on (1) the compilation of updated and harmonised versions of the databases required for probabilistic seismic hazard assessment, (2) the adoption of standard procedures and robust methods, especially for expert elicitation and consensus building among hundreds of European experts, (3) the multi-disciplinary input from all branches of earthquake science and engineering, (4) the direct involvement of the CEN/TC250/SC8 committee in defining output specifications relevant for Eurocode 8 and (5) the accounting for epistemic uncertainties of model components and hazard results. Furthermore, enormous effort was devoted to transparently document and ensure open availability of all data, results and methods through the European Facility for Earthquake Hazard and Risk (
 www.efehr.org
 ).

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The 2013 European Seismic Hazard Model: key components and results

This article presents the latest generation of ground-motion models for the prediction of elastic response (pseudo-) spectral accelerations, as well as peak ground acceleration and velocity, derived using pan-European databases. The models present a number of novelties with respect to previous generations of models (Ambraseys et al. in Earthq Eng Struct Dyn 25:371–400, 1996, Bull Earthq Eng 3:1–53, 2005; Bommer et al. in Bull Earthq Eng 1:171–203, 2003; Akkar and Bommer in Seismol Res Lett 81:195–206, 2010), namely: inclusion of a nonlinear site amplification function that is a function of $$\text{ V }_\mathrm{S30}$$
 and reference peak ground acceleration on rock; extension of the magnitude range of applicability of the model down to $$\text{ M }_\mathrm{w}$$
 4; extension of the distance range of applicability out to 200 km; extension to shorter and longer periods (down to 0.01 s and up to 4 s); and consistent models for both point-source (epicentral, $$\text{ R }_\mathrm{epi}$$
 , and hypocentral distance, $$\text{ R }_\mathrm{hyp}$$
 ) and finite-fault (distance to the surface projection of the rupture, $$\text{ R }_\mathrm{JB}$$
 ) distance metrics. In addition, data from more than 1.5 times as many earthquakes, compared to previous pan-European models, have been used, leading to regressions based on approximately twice as many records in total. The metadata of these records have been carefully compiled and reappraised in recent European projects. These improvements lead to more robust ground-motion prediction equations than have previously been published for shallow (focal depths less than 30 km) crustal earthquakes in Europe and the Middle East. We conclude with suggestions for the application of the equations to seismic hazard assessments in Europe and the Middle East within a logic-tree framework to capture epistemic uncertainty.

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Empirical ground-motion models for point- and extended-source crustal earthquake scenarios in Europe and the Middle East

Machine learning (ML) has evolved rapidly over recent years with the promise to substantially alter and enhance the role of data science in a variety of disciplines. Compared with traditional appro...

The promise of implementing machine learning in earthquake engineering: A state-of-the-art review

Presented herein is an updated model for empirical prediction of 5 %-damped elastic response spectra in the period range 0–10 s, peak ground acceleration and velocity, based on a global dataset of digital acceleration records. The predictive model features saturation of the shaking parameters with both magnitude $$M_{W}$$
 and distance $$R_{ RUP }$$
 , magnitude-dependent distance attenuation, alternative parameterisations of the amplification effects due to local site conditions (based either on ground types or $$V_{S,30}$$
 ) and corrective terms for style-of-faulting. The calibration dataset comprises more than $$1{,}880\times 2$$
 orthogonal horizontal accelerometer records with $$R_{ RUP }< 150$$
  km from 98 global earthquakes with $$4.5\le M_{W}\le 7.9$$
 . The processing technique applied to the acceleration data optimises the reliability of the predictions at long periods, as required by displacement-based design techniques. Developed independently of the recent NGA-West2 and RESORCE-based models, the new predictive tool effectively contributes to capturing the epistemic uncertainties associated with the prediction of seismic shaking levels for engineering applications.

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Updated predictive equations for broadband (0.01–10 s) horizontal response spectra and peak ground motions, based on a global dataset of digital acceleration records

Ground motion prediction equations

This paper presents 1 the overall procedure followed in order to assemble the most recent pan-European strong-motion databank: Reference Database for Seismic Ground-Motion in Europe (RESORCE). RESORCE is one of the by-products of the SeIsmic Ground Motion Assessment (SIGMA; projet-sigma.com) project. RESORCE is intended to be a single integrated accelerometric databank for broader Europe to understand the regional differences in seismic hazard for improving risk studies in Europe and surrounding countries. RESORCE principally updates and extends the previous pan-European strong-motion data-bank (Ambraseys in Bollettino di Geofisica Teorica ed Applicata 45:113-129, 2004a) from recently compiled Greek, Italian, Swiss and Turkish accelerometric archives. The updates also include the earthquake-specific literature studies published in recent years. The current content of RESORCE includes 5,882 multi-component and uniformly processed accelerograms from 1,814 events and 1,540 strong-motion stations. The moment magnitude range covered by RESORCE is 2.8 Mw 7.8. The source-to-site distance interval extends to 587 km and distance information is given by the common point- and extended-source distance measures. The paper presents the current features of RESORCE through simple statistics that also quantify the differences in metadata and strong-motion processing with respect to the previous version of the pan-European strong-motion databank.

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Reference database for seismic ground-motion in Europe (RESORCE)

In a companion article Akkar et al. (Bull Earthq Eng, doi:
 10.1007/s10518-013-9461-4
 , 2013a; Bull Earthq Eng, doi:
 10.1007/s10518-013-9508-6
 , 2013b) present a new ground-motion prediction equation (GMPE) for estimating 5 %-damped horizontal pseudo-acceleration spectral (PSA) ordinates for shallow active crustal regions in Europe and the Middle East. This study provides a supplementary viscous damping model to modify 5 %-damped horizontal spectral ordinates of Akkar et al. (Bull Earthq Eng, doi:
 10.1007/s10518-013-9461-4
 2013a; Bull Earthq Eng, doi:
 10.1007/s10518-013-9508-6
 , 2013b) for damping ratios ranging from 1 to 50 %. The paper also presents another damping model for scaling 5 %-damped vertical spectral ordinates that can be estimated from the vertical-to-horizontal (V/H) spectral ratio GMPE that is also developed within the context of this study. For consistency in engineering applications, the horizontal and vertical damping models cover the same damping ratios as noted above. The article concludes by introducing period-dependent correlation coefficients to compute horizontal and vertical conditional mean spectra (Baker in J Struct Eng 137:322–331, 2011). The applicability range of the presented models is the same as of the horizontal GMPE proposed by Akkar et al. (Bull Earthq Eng, doi:
 10.1007/s10518-013-9461-4
 2013a; Bull Earthq Eng, doi:
 10.1007/s10518-013-9508-6
 , 2013b): as for spectral periods $$0.01 \hbox { s}\le \,\hbox {T}\le \,4\hbox { s}$$
 as well as PGA and PGV for V/H model; and in terms of seismological estimator parameters $$4\le \hbox {M}_\mathrm{w} \le 8, \hbox { R} \le 200 \hbox { km}, 150\hbox { m/s}\le \hbox { V}_\mathrm{S30}\le $$
 1,200 m/s, for reverse, normal and strike-slip faults. The source-to-site distance measures that can be used in the computations are epicentral $$(\hbox {R}_\mathrm{epi})$$
 , hypocentral $$(\hbox {R}_\mathrm{hyp})$$
 and Joyner–Boore $$(\hbox {R}_\mathrm{JB})$$
 distances. The implementation of the proposed GMPEs will facilitate site-specific adjustments of the spectral amplitudes predicted from probabilistic seismic hazard assessment in Europe and the Middle East region. They can also help expressing the site-specific design ground motion in several formats. The consistency of the proposed models together with the Akkar et al. (Bull Earthq Eng, doi:
 10.1007/s10518-013-9461-4
 2013a; Bull Earthq Eng, doi:
 10.1007/s10518-013-9508-6
 , 2013b) GMPE may be advantageous for future modifications in the ground-motion definition in Eurocode 8 (CEN in Eurocode 8, Design of structures for earthquake resistance—part 1: general rules, seismic actions and rules for buildings. European Standard NF EN 1998-1, Brussels, 2004).

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Compatible ground-motion prediction equations for damping scaling factors and vertical-to-horizontal spectral amplitude ratios for the broader Europe region

Since 1976, the General Directorate of Disaster Affairs of Turkey has deployed several strong-motion accelerographs at selected sites, particularly along the North Anatolian Fault zone. Within the framework of the project entitled Compilation of National Strong Ground Motion Database in Accordance with International Standards, initiated in 2006, site conditions at a total of 153 strong-motion sites were investigated within the upper 30 m depth through boreholes including Standard Penetration Testing (SPT) and surface seismics. A preliminary assessment of the site characterization was held by making use of the mean shear-wave velocity of the uppermost 30 m depth with reference to the NEHRP provisions. The recorded accelerograms and corresponding catalogue information were compiled for these strong-motion sites using the available information from national and international databases. The 5% damped normalized elastic acceleration spectra of the accelerograms recorded for events with M w ⩾ 4.0 were computed and categorized according to the site class and M w . Mean normalized spectra computed for different M w and site class bins were compared in order to investigate the significance of site class on the spectral response. NEHRP site classification is evaluated within the limitations of available data and findings.

M. A. Sandikkaya

Papers

Reference database for seismic ground-motion in Europe (RESORCE)

Compatible ground-motion prediction equations for damping scaling factors and vertical-to-horizontal spectral amplitude ratios for the broader Europe region

An Evaluation of Site Classification for National Strong-Motion Recording Stations in Turkey