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We updated the earthquake strong-motion database of Türkiye (SMD-TR) that is initially compiled by Akkar et al. The updated data set consists of of 9244 earthquakes of magnitudes 3.0 ≤ M ≤ 7.8 that occurred between 1976 and 2023. It includes 95,890 three-component waveforms recorded at 1022 stations (55,375 records that are processed from 6710 events and 974 stations). The database is disseminated under research-oriented website DesignSafe (https://doi.org/10.17603/ds2-f21x-s189) and is compiled to provide ground-motion flatfile, which will be updated periodically until 2025. The released version includes events occurred in Türkiye until 28 February 2023, and hence, it comprises of the mainshocks and a great portion of aftershocks from the February 6th, 2023, Kahramanmaraş earthquakes. The database includes event metadata compiled from national and international seismological agencies as well as the literature. We classified events according to their tectonic environments (i.e. active crustal and subduction) and identified the aftershocks. The station information provided by AFAD1 was used to compute the major site parameters, including time-based average of shear-wave velocity of uppermost 30 m (VS30) and depth-to-rock horizon at which the shear-wave velocity (VS) attains 1 km/s (Z1). We also computed the finite-fault distance metrics and flagged the stations located on the hanging-wall side of the rupture, as well as identified pulse-like records. We developed an automatic processing algorithm to determine the waveform quality, apply appropriate filtercut-offs to remove low- and high-frequency noise, and compute ground-motion parameters. The automatic processing was applied to small-magnitude (M < 5.5) events, whereas manual processing scheme is preferred for waveforms recorded from larger events (M ≥ 5.5). The peak ground-motion values, spectral ordinates, and ground-motion duration are provided along with the key data processing parameters in the flatfile. [ABSTRACT FROM AUTHOR]

We assess the significance of rupture-plane uncertainty in the estimated ground-motion intensity measures (IMs) by using the centroid moment-tensor and fault-plane solutions as well as the ground-motion recordings of the 30 October 2020 Samos Earthquake. We sampled ground-motion fields using stochastically generated rupture planes by considering the uncertainties imposed from alternative fault-plane solutions to reach our objective. Our observations indicate that the compromise between rupture-plane uncertainty and variability in the predicted ground-motion IMs depends on the modeling complexity of the ground-motion predictive model (GMPM). It also depends on the spatial location of the site relative to the ruptured fault. This conclusive remark is important for modelers who perform regional or site-specific seismic hazard and risk analyses. The presented case studies are also useful for GMPM developers because the ground-motion models contain predictor parameters, the most ubiquitous one is source-to-site distance, that are affected from rupture-plane geometry. Depending on the level of model complexity, the number of predictor parameters affected from rupture-plane geometry can increase and therefore the estimated ground-motion IMs can become more prone to rupture-plane uncertainty. Confined to our case-specific observations, we intend to make some suggestions to hazard, risk, and GMPM modelers for the consideration of rupture-plane uncertainty at the end of the paper. [ABSTRACT FROM AUTHOR]

This article presents comparisons among the five ground-motion models described in other articles within this special issue, in terms of data selection criteria, characteristics of the models and predicted peak ground and response spectral accelerations. Comparisons are also made with predictions from the Next Generation Attenuation (NGA) models to which the models presented here have similarities (e.g. a common master database has been used) but also differences (e.g. some models in this issue are nonparametric). As a result of the differing data selection criteria and derivation techniques the predicted median ground motions show considerable differences (up to a factor of two for certain scenarios), particularly for magnitudes and distances close to or beyond the range of the available observations. The predicted influence of style-of-faulting shows much variation among models whereas site amplification factors are more similar, with peak amplification at around 1s. These differences are greater than those among predictions from the NGA models. The models for aleatory variability (sigma), however, are similar and suggest that ground-motion variability from this region is slightly higher than that predicted by the NGA models, based primarily on data from California and Taiwan. [ABSTRACT FROM AUTHOR]

We introduce a procedure for selecting and ranking of ground-motion prediction equations (GMPEs) that can be useful for regional or site-specific probabilistic seismic hazard assessment (PSHA). The methodology is called Euclidean distance-based ranking (EDR) as it modifies the Euclidean distance (DL) concept for ranking of GMPEs under a given set of observed data. DE is similar to the residual analysis concept; its modified form, as discussed in this paper, can efficiently serve for ranking the candidate GMPEs. The proposed procedure separately considers groundmotion uncertainty (i.e., aleatory variability addressed by the standard deviation) and the bias between the observed data and median estimations of candidate GMPEs (i.e., model bias). Indices computed from the consideration of aleatory variability and model bias or their combination can rank GMPEs to design GMPE logic trees that can serve for site-specific or regional PSHA studies. We discussed these features through a case study and ranked a suite of GMPEs under a specific ground-motion database. The case study indicated that separate consideration of ground-motion uncertainty (aleatory variability) and model bias or their combination can change the ranking of GMPEs, which also showed that the ground-motion models having simpler functional forms generally rank at the top of the list. We believe that the proposed method can be a useful tool to improve the decision-making process while identifying the most proper GMPEs according to the specific objectives of PSHA. [ABSTRACT FROM AUTHOR]

SUMMARY A large scale seismic risk prioritization study was conducted for medium-rise, gravity-designed reinforced concrete residential buildings in Istanbul. The implemented procedure was based on evaluating selected building parameters that could be easily observed or measured during a systematic sidewalk survey. The survey was actually conducted on approximately 100,000 buildings in the six subprovinces of Istanbul over the period 2004-2009 by a large team of trained surveyors. The collected data were processed to calculate a safety score for each building, which is in turn used for ranking the surveyed buildings with respect to their expected seismic performance under the calculated ground motion intensities produced for a scenario earthquake of M7.5 along the Marmara Sea Fault. The basic objective of this laborious study was to identify the buildings that would be likely to sustain severe damage or suffer collapse during the expected Istanbul earthquake. Accordingly, a rational risk reduction planning can be conducted for minimizing the life and property losses. This paper presents the methodology, results of field surveys and risks evaluated in 100,000 buildings. As a result, 52,000 buildings have been classified as 'high risk', that is, expected to sustain severe damage or collapse during the scenario event. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ground-motion prediction equations (GMPEs) for spectral accelerations have traditionally focused on the range of response periods most closely associated with the dynamic characteristics of buildings. Providing predictions only in this period range (from 0.1 to 2 or 3 s) has also accommodated the assumed limitations on the usable period range resulting from the processing of accelerograms. There are, however, engineering applications for which estimates of spectral ordinates are required at shorter response periods. Recent work has demonstrated that high-frequency spectral ordinates are relatively insensitive to record processing, contrary to previous assumptions. In the light of this finding, additional regressions are performed to extend a recent pan-European GMPE to higher response frequencies. This model and others that also include coefficients for spectral ordinates at several high response frequencies are used to explore options for interpolating coefficients for equations that do not provide good coverage in this range. The challenges and uncertainties associated with such interpolations are discussed. The paper concludes that a set of standard response frequencies could be usefully established for future GMPEs. [ABSTRACT FROM AUTHOR]

The range of response frequencies for which spectral ordinates obtained from accelerograms may be considered reliable is limited by several factors, primary among them being the effects of filters that are routinely applied to remove noise from the records. Considerable attention has been focused on the low-frequency limit of the usable spectral ordinates because of various engineering applications requiring long-period spectral accelerations or displacements but only recently have rational approaches to selecting the high-frequency limit been proposed. Since there are applications for which the high-frequency spectral ordinates are important, the approaches to this issue presented in the recent studies are reviewed and their application to the ground-motion database from Europe and the Middle East is explored. On the basis of the results of these analyses, it is concluded that a large proportion of this dataset can be used to provide reliable estimates of response spectral ordinates at much shorter periods than may have previously been considered feasible. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We examined the differences between the ground-motion estimations of local and global prediction equations and explored some seismological parameters that may explain these differences. To achieve this objective, we first derived a set of ground-motion prediction equations (GMPEs) for estimating peak horizontal acceleration, velocity, and pseudospectral acceleration using the recently compiled Turkish ground-motion database. The new GMPEs are comparable with the recent global GMPEs in terms of model sophistication, and they are based on a well-studied national dataset. Using global GMPEs from the Next Generation Attenuation of Ground Motions project (Power et al, 2008) and the pan-European Akkar and Bommer (2010) model, we observed that the discrepancy between local and global GMPEs is more prominent at small magnitudes provided that the GMPEs possess similar magnitude limits. Our more detailed comparisons with the pan-European Akkar and Bommer (2010) predictive model, as well as with the estimations from a combined Italian and Turkish accelerometric dataset, indicate that depth can be of importance for delineating the differences between local and global GMPEs. [ABSTRACT FROM AUTHOR]

Strong motion data recorded by the Turkish national strong motion network has been compiled and processed systematically for the first time, together with detailed geophysical and geotechnical site measurements for all of its stations. The catalog information of 18 seismological agencies and other sources were examined to obtain reliable source, geometry, and distance parameters for each event. The high quality digital and analog strong motion data was processed by a uniform methodology to remove the high- and low-frequency noise. Currently, the seismological and spectral information of 4,607 strong motion records are available for use by earth scientists and earthquake engineers. In this article, we present the fundamental features of this database and explain our methodology in their calculation. We present several comparisons of our database with other related studies to verify our approach during the computational stage of the seismological parameters. The results confirm the reliability of our calculations. The database has also enabled us to derive empirical magnitude conversion relationships to estimate moment magnitude in terms of different magnitude scales. The article ends with a discussion of the likely improvements in the European accelerometric data through contributions from this strong motion database applicable for seismically active shallow-crust regions. The findings of this article emphasize the necessity of global strong motion databases in Europe for better estimation of seismic hazard in regions of similar seismotectonic environment. [ABSTRACT FROM AUTHOR]

A key issue in the assessment of seismic hazard in regions of low-to- moderate seismicity is the extent to which accelerograms obtained from small-magnitude earthquakes can be used as the basis for predicting ground motions due to the larger-magnitude events considered in seismic hazard analysis. In essence, the question is whether empirical ground-motion prediction equations can be applied outside their strict range of applicability as defined by the magnitude and distance ranges covered by the datasets from which they are derived. This question is explored by deriving new spectral prediction equations using an extended strong-motion dataset from Europe and the Middle East covering the magnitude range Mw 3.0-7.6 and comparing the predictions with previous equations derived using data from only Mw 5.0 and above events. The comparisons show that despite their complex functional form, including quadratic magnitude-dependence and magnitude-dependent attenuation, the equations derived from larger-magnitude events should not be extrapolated to predict ground motions from earthquakes of small magnitude. Moreover, the results suggest not only that ground-motion prediction equations cannot be used outside the ranges of their underlying datasets but also that their applicability at the limits of these ranges may be questionable. Although only tested for smaller magnitudes, the results could be interpreted to suggest that predictive equations also cannot be reliably extrapolated to higher magnitudes than those represented in the dataset from which they are derived, a finding that has important implications for seismic hazard analysis. The conclusion of the study is that empirical derivation of ground-motion prediction equations should be based on datasets extending at least one unit below the lower limit of magnitude considered in seismic hazard calculations. The inclusion of small-magnitude recordings results in a significant increase in the aleatory variability of the equations, although it is yet to be established whether this is due to greater uncertainty in the associated metadata or whether ground-motion variability is genuinely dependent on earthquake magnitude. [ABSTRACT FROM AUTHOR]

A simple procedure to estimate the local displacement demands in regular frame-type structures that respond in elastic limits is described. Given the spectral displacement and beam-to-column stiffness ratio, the procedure estimates the maximum ground story and maximum interstory drifts along the height of the structure. A total of 145 near-fault ground motions recorded on dense-to-firm soil sites are used for the evaluation of the procedure. The approximate drift demands computed from this procedure and the exact results from 27,550 response history analyses are used for calculating the error statistics. The calculations show that the procedure can be used with confidence for frames with fundamental periods between 0.3 and 1.5 s when they are subjected to near-fault records without pulse. The approximations are in good agreement with the exact response history results of near-fault records with pulse when the fundamental period to pulse period ratio is less than 1.5. The performance of the new procedure is also compared with other approximate methods that are employed for similar purposes. The method can be useful for preliminary design of new structures or rapid assessment of existing buildings. [ABSTRACT FROM AUTHOR]

A statistical study is presented to evaluate the accuracy of five approximate methods that have been proposed in the past to estimate the maximum inelastic deformation demand on existing structures. Three are based on equivalent linearization in which the inelastic deformation is approximated by the maximum deformation of an equivalent linear elastic system having lower lateral stiffness and larger viscous damping with respect to the preyielding properties of the inelastic system. In the equivalent linear methods evaluated here the equivalent period and equivalent damping ratio are computed as a function of the maximum deformation through the displacement ductility ratio. The other two methods estimate the maximum inelastic deformation of a system by modifying its maximum elastic deformation through a displacement modification factor. Modification factors depend on the initial period of vibration and its lateral strength. A relatively large number of earthquake ground motions recorded on sites having average shear wave velocities higher than 180 m/s are used to calculate error statistics. For each method mean errors and standard errors, as well as probability of underestimating or overestimating inelastic deformations, are presented and discussed. [ABSTRACT FROM AUTHOR]

Lateral strengths required to avoid dynamic instability of single-degree-of-freedom systems are examined. Oscillators with a bilinear hysteretic behavior with negative postyield stiffness are considered. Mean lateral strengths normalized by the lateral strength required to maintain the system elastic are computed for systems with periods ranging from 0.2 to 3.0 s when subjected to 72 earthquake ground motions recorded on firm soil. The effect of the period of vibration and postyield stiffness are investigated. Results indicate that mean normalized lateral strengths required to avoid dynamic instability decrease as negative postyield stiffness increases and that the reductions are much larger for small negative postyield stiffness than for severe negative postyield stiffnesses. It is concluded that there is a significant influence of the period of vibration for short-period systems and for systems with mildly negative postyield stiffnesses. Dispersion of normalized lateral strengths required to avoid dynamic instability are found to increase as the negative postyield stiffness decreases and as the period of vibration increases. Simple equations that capture the effects of period and postyield stiffness to aid in the evaluation of existing structures are obtained through nonliner regression analyses. [ABSTRACT FROM AUTHOR]

We introduce a site factor computation method for a region by extending the site-specific and probabilistic site amplification approach in Bazzuro and Cornell (2004). The site-factor exceedance probability is estimated from the exceedance probabilities of the reference rock ground motion and the soil amplification conditioned on the reference rock ground motion. The former probability is represented by regional hazard curves. The latter probability is computed from soil amplification models. The proposed method is capable of yielding site factors for a target exceedance probability. This property does not exist in the current code-based site factors. Given a site class, if the site factors and the reference rock spectrum possess the same exceedance probability the resulting spectrum would have the same probability of exceedance. The use of such probabilistically consistent earthquake demands would be more relevant for probability-based seismic design and assessment. Owing to the use of hazard curves, the proposed method can account for regional seismicity in the computation of site factors. • Examines Eurocode 8 and NEHRP site factors. • Period dependency and nonlinear soil behavior should be considered in site factors. • Computes probabilistically the hazard-consistent site factors for a region. • NEHRP site factors are found sufficient but more realistic site factors are computed. [ABSTRACT FROM AUTHOR]