Engineering Strong Motion Research Articles

A novel deep learning-based method for generating floor response spectra of building structures

Accurately and efficiently generating floor response spectra is crucial for the seismic design and analysis of nonstructural components, and seismic analysis of equipment placed on floors. In this article, a direct spectra-to-spectra method for generating floor response spectra is designed based on deep learning algorithms. The dataset was developed using the records of 102 building observation arrays in the Center for Engineering Strong Motion Data, which included 48 concrete structures, 44 steel structures and 10 masonry structures. The procedure involves training a deep learning model (FRSNet) with the ground response spectra and easily obtained structural parameters as inputs and the floor response spectra as outputs. Analysis results show that the prediction performance of the model is good on concrete structures, steel structures and masonry structures. The proposed model has sufficient accuracy, and the prediction performance is better than that of other models compared in this article. Finally, the proposed model is validated through two numerical models, a shaking table model structure and an actual structure. Convincing results confirm the accurate prediction capabilities of the proposed method.

Analysis of depth spatial variations of accelerograms recorded from the Center for Engineering Strong Motion Data: Numerical Simulation for Multipoint Ground Motions

Analysis of depth spatial variations of accelerograms recorded from the Center for Engineering Strong Motion Data: Numerical Simulation for Multipoint Ground Motions

A non-parametric model of ground motion parameters for shallow crustal earthquakes in Europe

The current study focuses on deriving ground motion models (GMMs) for 21 ground motion parameters derived from data sourced from the Engineering Strong Motion (ESM) database. These parameters include Peak Ground Acceleration (PGA), Peak Ground Velocity (PGV), Peak Ground Displacement (PGD), PGV-to-PGA ratio, (V/H) PGA ratio Predominant Frequency (Fp), Central Frequency (Ω), Spectral Parameter (q), Significant Duration (TSig), Root Mean Square Acceleration (Arms), Arias Intensity (Ia), Cumulative Absolute Velocity (CAV), Characteristic Intensity (IC), Acceleration Spectrum Intensity (ASI), Velocity Spectrum Intensity (VSI), Total Energy (Eacc), Spectral Centroid (Ew), Spectral Standard Deviation (Sw), Temporal Centroid (Et), Temporal Standard Deviation (St), and Correlation between time and frequency [ρ(t,ω)]. Both horizontal and vertical components are considered in this study. The inherent random effects within ground motion regression, encompassing inter-event, inter-site, inter-locality, and inter-region variabilities, are addressed using cross-nested mixed effect regression utilizing a non-parametric GMM approach employing Artificial Neural Network (ANN). Quantitative assessment of the models involves correlation coefficients for regression through the origin and error measures like mean squared error and mean absolute error. These findings of the assessment confirm reliable estimates of Ground Motion Parameters (GMPs). A comparison of GMPs computed using the proposed model and those reported in the literature indicated model's superior performance. Furthermore, satisfactory performance of the proposed GMM in ground motion simulation for the ESM region is demonstrated.

Elastic and inelastic acceleration amplification of nonstructural components characterized using recorded building responses

This paper presents a comprehensive study of the acceleration (or force) amplification behavior of building nonstructural components characterized using a large set of recorded building responses available in the Center for Engineering Strong Motion Data (CESMD) repository. The elastic acceleration amplification demands of nonstructural components are analyzed statistically and subsequently compared with the corresponding inelastic demands characterized by the constant-ductility floor response spectra. Different simplified hysteretic rules are adopted for evaluating the inelastic acceleration responses of nonstructural components. The numerical study demonstrates that the elastic acceleration amplification characteristics of the nonstructural components are highly dependent on their natural periods relative to the specific vibration modes of the supporting structures as well as their attachment locations relative to the building height. The presence of component ductility effectively reduces their seismic acceleration demands, particularly in period ranges tuned with their supporting structures. Furthermore, the hysteretic behavior of nonstructural components may moderately modify their acceleration amplification effects. Findings from this study substantiate current seismic design provisions of nonstructural components with evidence derived from building floor responses recorded during real earthquakes.

Comparative Analysis of Multistorey RCC and Semi-Rigid Steel Frame with Cross Bracings Subjected to Mainshock and Aftershock Earthquake Sequence

Strong Ground Motions have a significant impact on structural analysis and design. Seismic evaluation is deemed necessary for the quality, reliability, and feasibility of existing and developing structures. Earthquakes are even more disastrous when a mainshock is succeeded and preceded by aftershocks of higher magnitude. Most of the time, these aftershocks are ignored during analysis. In the last few decades, steel buildings have been crucial to the construction sector. On the other hand, RCC frames are commonly designed structures for commercial purposes and cost-effectiveness. IS 1893 (Part:1)-2002 Criteria for Earthquake Resistant Design of Structures and IS 13920-2016 Ductile Detailing of RC Structures Subjected to Seismic Reactions are majorly used for Seismic Analysis. Steel bracings in the structural system increase the ductility and stiffness of the frame structure. That can be arranged in a variety of ways, such as X, diagonally, alternatively, V, inverted V, K, etc. Cross bracings are used in this paper for the design of a typical multi-story (G+9) semi-rigid steel frame and a typical RCC frame is designed of the same dimensions. Both the frames are modelled and compared using ETABS software and a static nonlinear Time History analysis is executed to examine the performance of both the frames under the Mainshock and Aftershock of Chamoli earthquake. The Mainshock and Aftershock results of the Chamoli earthquake are extracted from the Centre for Engineering Strong Motion Research Ground Motion Database. Base shear, joint displacement, kinetic energy, and story displacement are a few of the variables of Time History Analysis that affect how well a building performs during mainshock and aftershock earthquakes. When analysing the outcomes, it is important to take into account that each of these factors significantly affects how a building responds to seismic loads.

Analysis of Multistorey RCC Frame subjected to Mainshock and Aftershock Earthquake

Abstract: Structure analysis and design are significantly influenced by earthquake. It is believed that seismic evaluation is required for the viability and serviceability of both present and future building structures. When a structure's base is subjected to a certain type of ground motion, a time history analysis is performed to examine the dynamic reaction of the structure at each time interval. The near-field earthquake ground motion verification may have specific impacts for both forward and backward directivity. The initial's velocity and displacement motions, respectively, exhibit pulse and fling-step characteristics. Therefore, it is crucial to assess how well structures built solely to withstand the primary shock would work through future aftershocks. Using modern seismic protection systems, such as base isolations or / and supplemental dampening devices, that significantly reduce building damages during main shocks and their related aftershocks is one of the appropriate solutions to this issue. Due to changes in both static and dynamic stress that take place during the earthquake process, aftershock events are set off by the primary shock. In order to better understand the ground motion features of a sizable collection of mainshock and subsequent aftershock ground motion data recorded in accelerograph stations around the region, this study reviews pertinent literature in the field. The G+9 RCC building will be used in this study to conduct a time history analysis of the mainshock and aftershock data of the Chamoli earthquake provided by the Centre for Engineering Strong Motion Research Ground Motion Database. For designing purposes, the IS 456-2000 code is taken into consideration. Live loads are measured in accordance with IS 875-part 1, and seismic zone IV is selected for analysis in accordance with IS 1893-2016. Storey drift, base shear, joint reactions, and storey displacement are just a few of the variables that can have an impact on how well a building performs. Since each of these variables has a significant impact on how a structure responds to seismic loads, they are also taken into account when evaluating the results.

INGe: Intensity-ground motion data set for Italy

In this paper we present an updated and homogeneous earthquake dataset for Italy compiled by joining the intensities available in the Italian Macroseismic Database DBMI15 and the peak ground motion (PGM) parameters present in the Engineering Strong-Motion (ESM) accelerometric data bank. The database has been compiled through an extensive procedure of evaluation and revision based on two main steps: 1) the selection of the earthquakes in DBMI15 with homogeneous macroseismic intensities in terms of data sources and 2) the extraction of all the localities reporting intensity data which are located within 3 km from the accelerograph stations that recorded the data. The final dataset includes 519 intensity-PGM data pairs from 65 earthquakes and 227 stations in the time span 1972–2016. The reported intensities are expressed either in the Mercalli-Cancani- Sieberg (MCS) or the European macroseismic (EMS-98) scales. The events are characterized by magnitudes in the range 4.1–6.8 and depths in the range 0–55 km. Here, we illustrate the data collection and the properties of the database in terms of recording, event and station distributions as well as macroseismic intensity points. Furthermore, we discuss the most relevant features of engineering interest showing several statistics with reference to the most significant metadata (such as moment magnitude, several distance metrics, style of faulting etc). The dataset is expected to be useful for benchmarking existing and for developing new ground motion intensity conversion equations offering a common basis, and sparing the time and effort required for assembling to the interested researchers. The dataset is available at https://zenodo.org/record/4623732#.YNX-AZMzbdc.

Simplified procedure for simulating artificial non-stationary multi-point earthquake accelerograms

A simplified procedure is proposed to generate artificial non-stationary multi-point ground motion inputs for the dynamic seismic analysis of long span or large scale structures. The probability distribution parameters for the phase difference were fitted using 438 recordings selected from Center for Engineering Strong Motion Data. Then the time curve of the number of zero crossings were fitted using the same dataset. By implementation of the empirical coherency function, we simulated the non-stationary multi-point artificial ground motions given design earthquake scenario (i.e. magnitude and epicentral distance) of the target site. The generated artificial recordings successfully account for non-stationarity in both the time domain and frequency domain, and the trend of spatial correlation is consistent with the utilized coherency function. The generated artificial ground motions were then applied as multi-support excitations for dynamic time-history analysis of the 190 m continuous rigid-frame box girder bridge. Approximately 15%–30% structural response difference was observed between using multi-support excitations and uniform excitations. The vertical displacement amplitude regarding mid-span of the bridge using multi-support excitations is significantly larger than the results using the uniform excitations. For both uniform input and non-uniform input cases, it is also found that the structural response of studied bridge using fitted mean ± standard deviation time curves of number of zero crossings are smaller than the results using fitted mean time curve. The difference is largely caused by the various energy content of generated recordings that are indicated by Arias intensity. This study provides an efficient procedure to generate artificial non-stationary multi-point earthquake accelerograms without cumbersome computation cost, and could be easily implemented in engineering applications.

Near-source magnitude scaling of spectral accelerations: analysis and update of Kotha et al. (2020) model

Ground-motion models (GMMs) are often used to predict the random distribution of Spectral accelerations ( $$\mathrm{SAs}$$ ) at a site due to a nearby earthquake. In probabilistic seismic hazard and risk assessment, large earthquakes occurring close to a site are considered as critical scenarios. GMMs are expected to predict realistic $$\mathrm{SAs}$$ with low within-model uncertainty ( $${\upsigma }_{\upmu }$$ ) for such rare scenarios. However, the datasets used to regress GMMs are usually deficient of data from critical scenarios. The (Kotha et al., A Regionally Adaptable Ground-Motion Model for Shallow Crustal Earthquakes in Europe Bulletin of Earthquake Engineering 18:4091–4125, 2020) GMM developed from the Engineering strong motion (ESM) dataset was found to predict decreasing short-period $$\mathrm{SAs}$$ with increasing $${M}_{W}\ge {\mathrm{M}}_{\mathrm{h}}=6.2$$ , and with large $${\upsigma }_{\upmu }$$ at near-source distances $$\le 30\mathrm{km}$$ . In this study, we updated the parametrisation of the GMM based on analyses of ESM and the Near source strong motion (NESS) datasets. With $${\mathrm{M}}_{\mathrm{h}}=5.7$$ , we could rectify the $${M}_{W}$$ scaling issue, while also reducing $${\upsigma }_{\upmu }$$ at $${M}_{W}\ge {\mathrm{M}}_{\mathrm{h}}$$ . We then evaluated the GMM against NESS data, and found that the $$\mathrm{SAs}$$ from a few large, thrust-faulting events in California, New Zealand, Japan, and Mexico are significantly higher than GMM median predictions. However, recordings from these events were mostly made on soft-soil geology, and contain anisotropic pulse-like effects. A more thorough non-ergodic treatment of NESS was not possible because most sites sampled unique events in very diverse tectonic environments. We provide an updated set of GMM coefficients, $${\upsigma }_{\upmu }$$ , and heteroscedastic variance models; while also cautioning against its application for $${M}_{W}\le 4$$ in low-moderate seismicity regions without evaluating the homogeneity of $${M}_{W}$$ estimates between pan-European ESM and regional datasets.

A regionally adaptable ground-motion model for fourier amplitude spectra of shallow crustal earthquakes in Europe

Typical seismic ground-motion models predict the response spectral ordinates (GMM-SA), which are the damped responses of a suite of single-degree-of-freedom oscillators. Response spectra represent the response of an idealized structure to input ground-motion, but not the physics of the actual ground-motion. To complement the regionally adaptable GMM-SA of Kotha et al. (2020), we introduce a model capable of predicting Fourier amplitudes (GMM-FA); developed from the Engineering Strong Motion (ESM) dataset for pan-Europe. This GMM-FA reveals the very high variability of high frequency ground-motions, which are completely masked in a GMM-SA. By maintaining the development strategies of GMM-FA identical to that of the GMM-SA, we are able to evaluate the physical meaning of the spatial variability of anelastic attenuation and source characteristics. We find that a fully data-driven geospatial index, Activity Index (AIx), correlates well with the spatial variability of these physical effects. AIx is a fuzzy combination of seismicity and crustal parameters, and can be used to adapt the attenuation and source non-ergodicity of the GMM-FA to regions and tectonic localities sparsely sampled in ESM. While AIx, and a few other parameters we touch upon, may help understand the spatial variability of high frequency attenuation and source effects, the high frequency site-response variability—dominating the overall aleatory variance—is yet unresolvable. With the rapid increase in quantity and quality of ground-motion datasets, our work demonstrates the need to upgrade regionalization techniques, site-characterisation, and a paradigm shift towards Fourier ground-motion models to complement the traditional response spectra prediction models.

Implications of high-frequency decay parameter, “κ-kappa”, in the estimation of kinematic soil-structure interaction effects

In the present study, the difference between the peak seismic response measures recorded on building basements and those at nearby free-field conditions is studied by means of estimating the high-frequency spectral decay parameter, “κ” (known as “kappa”). Computation of “κ” is performed for selected accelerographic stations belonging to three strong motion networks, namely the Hellenic National Accelerographic Network (HNAN) in Greece, the Center for Engineering Strong Motion Data (CESMD) in California, USA and the Building Research Institute (BRI) in Japan. Parameter “κ” is computer according to Anderson and Hough (1984), while an automated signal energy-based procedure is developed to calculate the S-wave windows of each waveform, accounting for any errors. Site-specific restrictions on the upper frequency limit, f2, for the calculation of “κ” at the foundation level are imposed, based on the empirical transfer functions between foundation and free-field motions. Based on the above procedure, non-linear regression analyses are conducted to relate “κ”, as computed for free-field and foundation motions (κff, - κfnd), to magnitude Mw, source-to-site distance Repi and shear wave velocity VS30. Simulation of ground motions though the point-source stochastic method is accomplished, utilizing the regression expression to define “κ” and assess its effectiveness to predict the variation of intensity between free-field and foundation motions as a proxy for assessing soil-structure interaction effects. It is shown that the regression-based expressions, combined with stochastic simulations, consist a promising tool for correcting seismic motions recorded at a building foundation or basement levels and thus, for reliably predicting the corresponding intensity and characteristics of the actual “building-free” ground motions.

Accessing European Strong-Motion Data: An Update on ORFEUS Coordinated Services

AbstractStrong ground motion records and free open access to strong-motion data repositories are fundamental inputs to seismology, engineering seismology, soil dynamics, and earthquake engineering science and practice. This article presents the current status and outlook of the Observatories and Research Facilities for European Seismology (ORFEUS) coordinated strong-motion seismology services, namely the rapid raw strong-motion (RRSM) and the engineering strong-motion (ESM) databases and associated web interfaces and webservices. We compare and discuss the role and use of these two systems using the Mw 6.5 Norcia (Central Italy) earthquake that occurred on 30 October 2016 as an example of a well-recorded earthquake that triggered major interest in the seismological and earthquake engineering communities. The RRSM is a fully automated system for rapid dissemination of earthquake shaking information, whereas the ESM provides quality-checked, manually processed waveforms and reviewed earthquake information. The RRSM uses only data from the European Integrated Waveform Data Archive, whereas the ESM also includes offline data from other sources, such as the ITalian ACcelerometric Archive (ITACA). Advanced software tools are also included in the ESM to allow users to process strong-motion data and to select ground-motion waveform sets for seismic structural analyses. The RRSM and ESM are complementary services designed for a variety of possible stakeholders, ranging from scientists to the educated general public. The RRSM and ESM are developed, organized, and reviewed by selected members of the seismological community in Europe, including strong-motion data providers and expert users. Global access and usage of the data is encouraged. The ESM is presently the reference database for harmonized seismic hazard and risk studies in Europe. ORFEUS strong-motion data are open, “Findable, Accessible, Interoperable, and Reusable,” and accompanied by licensing information. The users are encouraged to properly cite the data providers, using the digital object identifiers of the seismic networks.

Study on the damping ratios of reinforced concrete structures from seismic response records

AbstractStructural damping ratio, which quantifies the energy dissipation of civil engineering structures under dynamic excitations, plays a critical role in structural seismic design and assessment. However, structural damping ratio is usually identified as an empirical value in design or as an optional parameter for different structure types as suggested in existing building seismic design guidelines. In the present work, the structural damping features of a variety of reinforced concrete (RC) structures under real ground motion excitations are further investigated by processing their response records reported in the Center for Engineering Strong Motion Data (CESMD) database. From the storey-by-storey methodology developed in this study, the equivalent damping ratios of the structures are estimated, and the time-varying effect of damping ratio is further explored, confirming the correlation between the damping ratio and the amplitude of ground motion. Based on a statistical analysis, an empirical relationship between the equivalent damping ratio and the peak ground acceleration (PGA) has been developed and validated, providing civil engineers with a refined basis for reasonably selecting the equivalent damping ratios during either the design or the post-earthquake assessment of RC structures.

Spectral decomposition of the Engineering Strong Motion (ESM) flat file: regional attenuation, source scaling and Arias stress drop

We perform a spectral decomposition of the Fourier amplitude spectra disseminated along with the Engineering Strong Motion (ESM) flat file for Europe and Middle East. We apply a non-parametric inversion schema to isolate source, propagation and site effects, introducing a regionalization for the attenuation model into three domains. The obtained propagation and source components of the model are parametrized in terms of geometrical spreading, quality factor, seismic moment, and corner frequency assuming a ω2 source model. The non-parametric spectral attenuation values show a faster decay for earthquakes in Italy than in the other regions. Once described in terms of geometrical spreading and frequency-dependent quality factor, slopes and breakpoint locations of the piece-wise linear model for the geometrical spreading show regional variations, confirming that the non-parametric models capture the effects of crustal heterogeneities and differences in the anelastic attenuation. Since they are derived in the framework of a single inversion, the source spectra of the largest events which have occurred in Europe in the last decades can be directly compared and the scaling of the extracted source parameters evaluated. The Brune stress drop varies over about 2 orders of magnitude (the 5th, 50th and 95th percentiles of the ∆σ distribution are 0.76, 2.94, and 13.07 MPa, respectively), with large events having larger stress drops. In particular, the 5th, 50th and 95th percentiles for M > 5.5 are 2.87, 6.02, and 23.5 MPa, respectively whereas, for M < 5.5, the same percentiles are 0.73, 2.84, and 12.43 MPa. If compared to the residual distributions associated to a ground motion prediction equation previously derived using the same Fourier amplitude spectra, the source parameter and the empirical site amplification effects correlate well with the inter-event and inter-station residuals, respectively. Finally, we calibrated both non-parametric and parametric attenuation models for estimating the stress drop from the ratio between Arias intensity and significant duration. The results confirm that computing the Arias stress drop is a suitable approach for complementing the seismic moment with information controlling the source radiation at high frequencies for rapid response applications.

2016–2017 Central Italy seismic sequence: strong-motion data analysis and design earthquake selection for seismic microzonation purposes

This work describes the analysis of the strong-motion data from the Engineering Strong Motion database (ESM, http://esm.mi.ingv.it ), aimed at: (1) extract a dataset of accelerometric waveforms recorded during the 2016–2017 Central Italy seismic sequence; (2) identify the recording stations to be used as reference sites for further seismological analysis; (3) select the records to be used as input for seismic microzonation of higher level at 137 municipalities. Firstly, a residual analysis is carried out on the extracted dataset to perform: (1) the quality check of the waveforms recorded by temporary networks installed soon after the occurrence of the first main shock (M 6.0, 24 August 2016); (2) the estimation of the site-to-site residual term for each recording station with the aim of recognising potential reference rock sites. Finally, the software REXELite, integrated within the ESM website, is adopted to select suites of spectrum-compatible accelerograms, that will be used as input for calculating site amplifications through 1D and 2D simulations at sites which suffered the greatest damage. The results of this work demonstrate the success of the synergy among Italian institutions. The setup of key infrastructures, such as emergency networks and data repositories, together with the knowledge developed during national projects, turned out to be successful in terms of timely intervention during the emergency phase and the planning of the post-emergency.

Geotechnical risk analyses and evaluation of design criteria of embankment dam systems

The integrity of the state and national system of embankment dams and levees is a crucial component in ensuring the safety of protected communities in any country. The failure of such systems due to natural or man-made hazards can have monumental repercussions, sometimes with dramatic and unanticipated consequences on human life, property and the economy of the states and the country. For highly seismic areas such as Southern California, it is critical to investigate and study the seismic response of embankment dams and levees for the afore mentioned reasons. While experimental studies of embankment dams under seismic loads is expensive, very time consuming, and limited, numerical studies usually suffer from lack of legitimate real data for verification of the developed models. However, organizations such as the California Strong Motion Instrumentation Program (CSMIP) instrument lifeline structures such as earth dams and levees with accelerometers and actively collect strong-motion data. The data obtained from CSMIP accelerometers is then processed by the Center for Engineering Strong Motion Data (CESMD) and made public for earthquake engineering applications. In this study, numerical models of existing earth embankment dams verified with site specific CESMD data are created in order to analyze their stability for a future earthquake, for post-earthquake response purposes. The seismic fragility of the modelled dams was assessed, providing insight for decision makers regarding priority areas important for matters such as maintenance, dam retrofit, or first-aid response locations for a hypothetical major earthquake. Society can benefit from increased awareness of the seismic response of the modelled structures and can be better prepared for a potential catastrophic seismic event.

LONG-PERIOD SEISMIC IMPACTS AND IT AFFECTING ON THE STRENGTH OF HIGH-RISE BUILDINGS CONSTRUCTIONS

Currently, in all building codes, the diagrams of dynamics coefficient are limited to a maximum natural oscillation period of 1.8 s. However, this range is clearly not enough for the calculation of constructions of high-rise structures with characteristic basic periods of about 4-5 s and more. This article analyzes the available seis-mological data presented in the Center for Engineering Strong Motion Data (CESMD) database. The spectra of Tolioku earthquakes (Tohoku earthquake. Japan. March 11. 2011) and Emberley (New Zealand Earthquake. New Zealand. November 13, 2016) were studied, and dynamic factors for periods of natural oscillations of structures 4-5 s are calculated. The results of the study allow to establish reasonable values of dynamic coefficients in the field of high periods.

The pan-European Engineering Strong Motion (ESM) flatfile: compilation criteria and data statistics

The Engineering Strong-Motion (ESM) flatfile is a parametric table which contains verified and reliable metadata and intensity measures of manually processed waveforms included in the ESM database. The flatfile has been developed within the Seismology Thematic Core Service of EPOS-IP (European Plate Observing System Implementation Phase) and it is disseminated throughout a web portal ( http://esm.mi.ingv.it/flatfile-2018/flatfile.php ) for research and technical purposes. The adopted criteria for flatfile compilation aim to collect strong motion data and related metadata in a uniform, updated, traceable and quality-checked way to develop Ground Motion Models (GMMs) for Probabilistic Seismic Hazard Assessment (PSHA) and engineering applications. In this paper, we present the characteristics of ESM flatfile in terms of recording, event and station distributions, and we discuss the most relevant features of the Intensity Measures (IMs) of engineering interest included in the table. The dataset for flatfile compilation includes 23,014 recordings from 2179 earthquakes and 2080 stations from Europe and Middle-East. The events are characterized by magnitudes in the range 3.5–8.0 and refer to different tectonics regimes, such as shallow active crustal and subduction zones. Intensity measures include peak and integral parameters and duration of each waveform. The spectral amplitudes of the (5% damping) acceleration and displacement response are provided for 36 periods, in the interval 0.01–10 s, as well as the 103 amplitudes of the Fourier spectrum for the frequency range 0.04–50 Hz. Several statistics are shown with reference to the most significant metadata for GMMs calibrations, such as moment magnitude, focal depth, several distance metrics, style of faulting and parameters for site characterization. Furthermore, we also compare and explain the most relevant differences between the metadata of ESM flatfile with those provided by the previous flatfile derived in RESORCE (Reference Database for Seismic Ground Motion in Europe) project.

The pan-European engineering strong motion (ESM) flatfile: consistency check via residual analysis

We present the results of a consistency check performed over the flatfile extracted from the engineering strong motion (ESM) database. The flatfile includes 23,014 recordings from 2179 earthquakes in the magnitude range from 3.5 to 7.8 that occurred since the 1970s in Europe and Middle East, as presented in the companion article by Lanzano et al. (Bull Earthq Eng, 2018a). The consistency check is developed by analyzing different residual distributions obtained from ad-hoc ground motion prediction equations for the absolute spectral acceleration (SA), displacement and Fourier amplitude spectra (FAS). Only recordings from earthquakes shallower than 40 km are considered in the analysis. The between-event, between-station and event-and-station corrected residuals are computed by applying a mixed-effect regression. We identified those earthquakes, stations, and recordings showing the largest deviations from the GMPE median predictions, and also evaluated the statistical uncertainty on the median model to get insights on the applicable magnitude–distance ranges and the usable period (or frequency) range. We observed that robust median predictions are obtained up to 8 s for SA and up to 20 Hz for FAS, although median predictions for Mw ≥ 7 show significantly larger uncertainties with ‘bumps’ starting above 5 s for SA and below 0.3 Hz for FAS. The between-station variance dominates over the other residual variances, and the dependence of the between-station residuals on logarithm of Vs30 is well-described by a piece-wise linear function with period-dependent slopes and hinge velocity around 580 m/s. Finally, we compared the between-event residuals obtained by considering two different sources of moment magnitude. The results show that, at long periods, the between-event terms from the two regressions have a weak correlation and the overall between-event variability is dissimilar, highlighting the importance of magnitude source in the regression results.

Strong-motion processing service: a tool to access and analyse earthquakes strong-motion waveforms

Strong-motion data processing is necessary to evaluate reliable ground-motion for standard or specific applications. We describe a processing web-service, fully integrated with the engineering strong motion database (ESM), a daily-updated strong-motion archive that contains more than 50,000 waveforms of events with magnitude ≥ 4.0, mainly recorded in the Pan-European region. A user-friendly web front-end allows the interactive use of a “robust” procedure (in the sense that it has been extensively tested), in order to select and process uncorrected waveforms from the ESM database, and derive several products: processed acceleration, velocity and displacement time series, as well as acceleration and displacement response spectra. The service is addressed to engineering seismologists, earthquake engineers, but also to students and professionals, if adequately trained.