Strong Motion Database Research Articles

ESMpro: A Proposal for Improved Data Management for the Engineering Strong-Motion Database (ESM)

AbstractThe strategy for data processing in the Engineering Strong-Motion Database (ESM) is to disseminate only manually revised data to ensure the highest quality. However, manual processing is no longer sustainable, due to the ever-increasing rate of digital earthquake records, from global, regional, and national seismic networks, and a new framework for strong-motion data processing is required, so that records are automatically processed and the human revision is restricted to selected significant records. To this end, we present ESMpro—a modular Python software for a renewed processing framework of ESM. The software is available in a stand-alone beta version to facilitate testing and sharing among the scientific community. ESMpro provides automatic settings for waveform trimming and filtering, along with the automatic recognition of poor-quality data and multiple events. ESMpro allows classifying each record in different quality classes to reduce manual revision on a subset of the incoming data. ESMpro also allows handling different processing techniques in a modular and flexible structure to facilitate the implementation of new or alternative algorithms and file formats. The testing performed on the ESM database results in a good correspondence between the automatic and manual data processing, supporting the migration toward fully automatic procedures for massive data processing.

A Review on the Selection of Real and Artificial Seismic Sequences for Analysis

A huge mainshock activates several aftershocks, divulging the public to serious risk and impeding building repair, rehabilitation, and restoration works. The performance of a structure during multiple earthquakes depends on structural properties and the characteristics of ground motion. Hence, the selection of seismic sequence plays a vital role in the analysis. Presumption of spatial and temporal characteristics of aftershocks is needed for the identification of these repeated motions. This paper further looks into statistical variability connected with aftershock sequences. A critical review of different real and artificial seismic sequences taken for the analysis is carried out. A few studies reveal that a strong motion database for procuring actual mainshock aftershock sequences could underrate the aftershock effects as the database is inadequate and imperfect. It is also observed that artificial sequences can take the place of real sequences especially when an ample data set of real mainshock aftershock sequences are not accessible.

Seismic Response of an Isolated Curved Bridge with Lead Rubber Bearing by Considering Design Aspect

Studies on the application of the lead rubber bearing (LRB) isolation system to various structures carried out as one of the measures to improve seismic performance. Curved bridges play noteworthy role in the modern transportation system. Due to complex interchange and the desire to conform to existing geometric confinements have made this type of structures more alluring. Horizontally curved bridges make up of a noteworthy portion of the bridge population in various countries. In the present study, Lead rubber bearings have been used in an Isolated Curved bridges. Seismic loadings have been considered for three recorded ground motions from PEER strong motion database (PEER 2014) without scaling viz. (1) Imperial Valley (1940) with two orthogonal horizontal ground motion components (PGA0.313g and PGA0.215g); (2) Kobe (1995) with two orthogonal horizontal ground motion components (PGA 0.83g and PGA 0.63g) and (3) Turkey (1992) with two orthogonal horizontal ground motion components (PGA 0.5g and PGA 0.39g). These three ground motions have been considered to represent conditions close to far-fault, near-fault and forward directivity of earthquakes, respectively. Unidirectional and Bi-directional loading have been considered in the present study. Design aspects of the Lead rubber bearings has been considered by deploying the interaction diagram of bearing displacement between the unidirectional and bi-directional responses. It has been found that the bidirectional loading should be considered while designing the isolators.

Study of the Target Earthquake-Induced Track Irregularity Spectrum under Transverse Random Earthquakes

Railway transportation, as an important lifeline during earthquake relief and post-disaster reconstruction, has an extremely significant role. The study of track irregularity caused by earthquakes is the basis for ensuring traffic safety after their occurrence. In this paper, a finite element model of a five-span simply supported high-speed railway beam bridge with the China Railway Track System (CRTS) II was established and an experimental verification was performed. Eighty arbitrarily selected seismic waves were extracted from the Pacific Earthquake Engineering Research Center (PEER) strong ground motion database and a nonlinear time-history analysis was performed on the finite element model. The frequency–domain distribution law of earthquake-induced track irregularities was studied. A stable target earthquake-induced track irregularity spectrum model was constructed, and its expression was fitted. According to the results, in the case of transverse earthquakes, the rails experienced noticeable alignment irregularity and cross-level irregularity, while the amplitude of the gauge and vertical irregularity were relatively small. The target irregularity spectrum has a higher amplitude in the low-frequency components. When peak ground acceleration (PGA) was low, earthquake-induced track irregularity was not obvious, but the deteriorating effects of earthquakes on track irregularities increased significantly with increasing PGA.

Stochastic Time-Series Prediction Equation Using Wavelet Packets for Iran

In this study, a stochastic simulation model proposed by Yamamoto and Baker (Bulletin of the Seismological Society of America 103:3044–3056, 2013) is applied to the Iranian strong motion database, which comprises more than 3828 recordings for the period between 1975 and 2018. Each ground motion is decomposed into wavelet packets. Amplitudes of wavelet packets are divided into two groups, and for each group, model parameters are estimated using the maximum likelihood method. Regression coefficients are then obtained relating model parameters to seismic characteristics such as earthquake magnitude, distance, and site condition. Inter-event residuals of coefficients and correlation of total residuals of those parameters are also calculated. An inverse wavelet packet transform is used to reconstruct the amplitudes in the time domain and perform the simulation. Finally, a validation test is performed. The comparison of ground motion intensity measures for recorded and simulated time series shows acceptable conformity in the application. The estimated parameters using the simulated data agree with the real data, indicating the acceptable validity of the estimated stochastic simulation model. The obtained regression equations can generate ground motions for future earthquake scenarios in Iran.

A Consistently Processed Strong-Motion Database for Chilean Earthquakes

Abstract Since the 1985 M 8.0 central Chile earthquake, national strong-motion seismic networks have recorded ten megathrust earthquakes with magnitudes greater than M 7.5 at the convergent margin, defined by the contact between the Nazca and South American plates. The analysis of these earthquake records have led to improved hazard analyses and design codes for conventional and seismically protected structures. Although strong-motion baseline correction is required for a meaningful interpretation of these records, correction methods have not been applied consistently in time. The inconsistencies between correction methods have been neglected in the practical use of these records in practice. Consequently, this work aims to provide a new strong-motion database for researchers and engineers, which has been processed by traceable and consistent data processing techniques. The record database comes from three uncorrected strong motion Chilean databases. All the records are corrected using a four-step novel methodology, which detects the P-wave arrival and introduces a baseline correction based on the reversible-jump Markov chain Monte Carlo method. The resulting strong motion database has more than 2000 events from 1985 to the date, and it is available to download at the Simulation Based Earthquake Risk and Resilience of Interdependent Systems and Networks (SIBER-RISK) project website.

Fragility-based seismic performance assessment of modular underground arch bridges

Seismic performance assessment of modular underground arch bridges (MUABs) can help mitigate structural damage to MUABs during earthquakes. This study proposed an efficient procedure to evaluate the seismic performance of a three-hinge MUAB by using fragility-based analysis. Firstly, a novel proposal for damage states was presented using the relationship between the crack depth and thickness of the arch component. The relationship between ground motion intensity and structural failure probability was then described using stratum-uncertainty characteristics. The multiple stripe analysis approach with the maximum likelihood function was introduced to detail the uncertainty characteristics of strata by allowing various ground motions at distinct seismic intensity levels. Finally, the collapse probability considering stratum-uncertainty characteristics was specified for seismic intensity and probability levels. The results revealed that the proposed procedure to randomly select ground motions from the strong-motion database of the Pacific Earthquake Engineering Research Center is feasible for evaluating the seismic vulnerability of MUABs. Therefore, the seismic performance of MUABs can be reasonably predicted under earthquakes.

Vertical spectra consistent with horizontal seismic hazard

Construction of vertical spectra (V) for scenario- and intensity-based seismic performance assessment is proposed based on scaling of the associated horizontal spectral ordinates (H) through respective V/H spectral ratios. Geometric mean of the spectra along and normal to the principal plane components is considered as the intensity measure of the horizontal component. V/H spectral shape is constructed using a large database (PEER-NGA-WEST2) of strong motion records contingent on the magnitude of the event, epicentral distance and average shear wave velocity. The procedure is based on the ratio of median vertical-to median horizontal-spectral ordinates which are shown to be well representative of the median of V/H spectral ratio. The construction is based on median response of the scenario and also applies to the design level (of a particular facility located in a specific site, which is also governed by a scenario) under certain assumptions and involves two steps: construction of normalized V/H spectra with unity at zero period scaled by the ratio of median vertical-to median horizontal- PGA (beta). The normalized V/H spectrum is shown to be characterized by three control points. An empirical estimate is proposed for beta as a function of epicentral distance. Normalized V/H spectra are further idealized for use with the intensity-based assessment per seismic codes. Vertical spectra using the proposed framework are compared with the various recommendations reported in the prior art including seismic codes and recorded events. PESMOS and COSMOS databases of strong motion events recorded in the Indian subcontinent are also used during the assessment.

Seismic site classification of the Costa Rican Strong-Motion Network based on VS30 measurements and site fundamental period

In this paper, a new seismic site classification for the Costa Rican Strong-Motion Network (CRSMN) is proposed. The soil profile classification of the Costa Rican Seismic Code based on the average shear-wave velocity of the top 30 m (VS30) is used as a reference. The site fundamental period (Tf) is included as a parameter to complement the existing characterization. For this, the VS30 measurements from 52 accelerometric stations are related to the site fundamental period obtained through horizontal-to-vertical spectral ratios (HVSR) using ground motion records from the Costa Rican Strong-Motion Database. The H/V ratios are estimated with 5% damped acceleration response spectra and with traditional Fourier amplitude spectra from the S-wave window. From the relation between VS30 and Tf, different ranges of Tf are assigned to the existing soil profile classification and a graph with three-lines and four-areas is proposed to classify the stations of the CRSMN.

強震動データベースに基づく機械学習による地震動評価モデルの構築

強震動データベースに基づく機械学習による地震動評価モデルの構築

A Methodological Approach to Update Ground Motion Prediction Models Using Bayesian Inference

In recent decades, prediction of ground motion at a specific site or a region is of primary interest in probabilistic seismic hazard assessment (PSHA). Historically, several ground motion prediction equation (GMPE) models with different functional forms have been published using strong ground motion records available from NGA-West and European databases. However, low-to-moderate seismicity regions, such as Central & Eastern United States and western Europe, is characterized by limited strong-motion records in the magnitude–distance range of interest for PSHA. In these regions, the available data for the development of empirical GMPEs is very scarce and limited to small magnitude events. For these regions, the general practice in PSHA is to consider a set of GMPEs developed from data sets collected in other regions with high seismicity. This practice generates an overestimation of the seismic hazard for the low seismicity regions. There are two potential solutions to overcome this problem: (1) a new GMPE model can be developed; however, development of such a model can require significant amount of data which is not usually available, and (2) the existing GMPE models can be recalibrated based on the data sets collected in the new region rather than developing a new GMPE model. In this paper, we propose a methodological approach to recalibrate the coefficients in a GMPE model using different algorithms to perform Bayesian inference. The coefficients are recalibrated for a subset of European Strong-Motion (ESM) database that corresponds to low-to-moderate seismicity records. In this study, different statistical models are compared based on the functional form given by the chosen GMPE, and the best model and algorithm are recommended using the concept of information criteria.

Seismic analysis of high-speed railway irregular bridge\u2013track system considering V-shaped canyon effect

To explore the effect of canyon topography on the seismic response of railway irregular bridge–track system that crosses a V-shaped canyon, seismic ground motions of the horizontal site and V-shaped canyon site were simulated through theoretical analysis with 12 earthquake records selected from the Pacific Earthquake Engineering Research Center (PEER) Strong Ground Motion Database matching the site condition of the bridge. Nonlinear seismic response analyses of an existing 11-span irregular simply supported railway bridge–track system were performed under the simulated spatially varying ground motions. The effects of the V-shaped canyon topography on the peak ground acceleration at bridge foundations and seismic responses of the bridge–track system were analyzed. Comparisons between the results of horizontal and V-shaped canyon sites show that the top relative displacement between adjacent piers at the junction of the incident side and the back side of the V-shaped site is almost two times that of the horizontal site, which also determines the seismic response of the fastener. The maximum displacement of the fastener occurs in the V-shaped canyon site and is 1.4 times larger than that in the horizontal site. Neglecting the effect of V-shaped canyon leads to the inappropriate assessment of the maximum seismic response of the irregular high-speed railway bridge–track system. Moreover, engineers should focus on the girder end to the left or right of the two fasteners within the distance of track seismic damage.

Earthquake record processing algorithms to form a strong motion database

This study is devoted to the development of algorithms and software for earthquake record processing. The algorithms are based on the methodology used by the Pacific Earthquake Engineering Research Center for the implementation of the scientific project NGA-West2. The purpose of processing is to determine reliable values of ground acceleration and other parameters of earthquakes from the available records of velocity time series. To analyze the operation of the algorithms, earthquake records (simultaneously recorded time series of acceleration and velocity) taken from the European Rapid Raw Strong-Motion database were used. The developed algorithms and the implemented software will allow in the future to form a database of strong motions for building regional attenuation models on the territory of the Russian Federation.

Determination of near-fault impulsive signals with multivariate na\xefve Bayes method

Near-fault ground motions may contain impulse behavior on velocity records. To calculate the probability of occurrence of the impulsive signals, a large dataset is collected from various national data providers and strong motion databases. The dataset has a large number of parameters which carry information on the earthquake physics, ruptured faults, ground motion parameters, distance between the station and several parts of the ruptured fault. Relation between the parameters and impulsive signals is calculated. It is found that fault type, moment magnitude, distance and azimuth between a site of interest and the surface projection of the ruptured fault are correlated with the impulsiveness of the signals. Separate models are created for strike-slip faults and non-strike-slip faults by using multivariate naïve Bayes classifier method. Naïve Bayes classifier allows us to have the probability of observing impulsive signals. The models have comparable accuracy rates, and they are more consistent on different fault types with respect to previous studies.

A Comparative Study of Response and Fourier Spectral Ratios on Classifying Sites

It has been known for decades that predominant periods of soil columns have crucial roles in the evaluation of site effects of ground motion. For this reason, detecting reliable site predominant periods relies upon a diligent data process and frequency domain transform method. In engineering seismology literature, predominant period-based site classifications have been developed to mitigate the local site effects of earthquakes. The main purpose of this study is to investigate the differences between Fourier and response spectral ratios in order to estimate the clear predominant periods and seismic site classes using instrumental accelerogram data. Within this framework, Fourier and response spectra of 26 installed strong ground motion stations in southern Turkey operated by AFAD [T.C. Disaster and Emergency Management Presidency, Strong Ground Motion Database of Turkey (TR-NSMN)] were examined. A total of 527 acceleration records with magnitude ranging from 3 to 5 having shallow crustal depths (0–25 km) and near-field earthquakes (< 150 km) have been analyzed. Elastic response and Fourier spectral ratios of horizontal-to-vertical (H/V) spectra were evaluated for a fair comparison using the S-wave phase. Although there are no significant differences, it was observed in this study that the response spectral ratio’s predominant periods reveal more reliable results for engineering purposes, especially in many sites where Fourier spectra show superficial peaks at engineering bedrock. As a pioneer study for a part of Turkey’s seismic station network, it will be an important step to establish a relationship between response and Fourier spectra to detect the site classes of stations alternatively in a global extent manner in the future.

Simulation of non-stationary stochastic ground motions based on recent Italian earthquakes

This work presents an up-to-date model for the simulation of non-stationary ground motions, including several novelties compared to the original study of Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996). The selection of the input motion in the framework of earthquake engineering has become progressively more important with the growing use of nonlinear dynamic analyses. Regardless of the increasing availability of large strong motion databases, ground motion records are not always available for a given earthquake scenario and site condition, requiring the adoption of simulated time series. Among the different techniques for the generation of ground motion records, we focused on the methods based on stochastic simulations, considering the time- frequency decomposition of the seismic ground motion. We updated the non-stationary stochastic model initially developed in Sabetta and Pugliese (Bull Seism Soc Am 86:337–352, 1996) and later modified by Pousse et al. (Bull Seism Soc Am 96:2103–2117, 2006) and Laurendeau et al. (Nonstationary stochastic simulation of strong ground-motion time histories: application to the Japanese database. 15 WCEE Lisbon, 2012). The model is based on the S-transform that implicitly considers both the amplitude and frequency modulation. The four model parameters required for the simulation are: Arias intensity, significant duration, central frequency, and frequency bandwidth. They were obtained from an empirical ground motion model calibrated using the accelerometric records included in the updated Italian strong-motion database ITACA. The simulated accelerograms show a good match with the ground motion model prediction of several amplitude and frequency measures, such as Arias intensity, peak acceleration, peak velocity, Fourier spectra, and response spectra.

Hellenic Strong-Motion Database with Uniformly Assigned Source and Site Metadata for the Period 1972–2015

AbstractWe present a Hellenic database of intensity measures from uniformly processed strong ground motion recordings, together with metadata on earthquake source attributes and recording site conditions. The database consists of information from 471 earthquakes between 1973 and 2015 that produced 2993 usable recordings from 333 sites. A key element of this work is a unified presentation of data from two major data providers that operate in Greece (Institute of Engineering Seismology and Earthquake Engineering and the Institute of Geodynamics, National Observatory of Athens) along with a university-operated local urban array (University of Patras). Consistent procedures were applied to develop source parameters that include hypocenter locations, moment magnitudes (directly estimated or derived using a conversion procedure), fault-plane solutions, and finite-fault parameters (generally, for events with M&amp;gt;6.0). The time-averaged shear-wave velocity in the upper 30 m parameter is provided for all 333 recording sites based on geophysical measurements where available (102) and proxy-based estimates otherwise. Most events are in the magnitude range of 3.8–7, occurred at shallow hypocentral depths (&amp;lt;30 km), and provide data for rupture distances generally between 10 and 300 km. The combined ground motion, seismic source, and site database is anticipated to be useful for engineering applications, including ground-motion model development and time series selection for response-history analyses.

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.

Evolution of the Kandilli Observatory and Earthquake Research Institute (KOERI) Seismic Network and the Data Center Facilities as a Primary Node of EIDA

AbstractAs the earliest institute in Turkey dedicated to locating, recording, and archiving earthquakes in the region, the Kandilli Observatory and Earthquake Research Institute (KOERI) has a long history in seismic observation, which dates back to the installation of its first seismometers soon after the devastating Istanbul earthquake of 10 July 1894. For over a century, since the deployment of its first seismometer, the KOERI seismic network has grown steadily in time. In this article, we present the KOERI seismic network facilities as a data center for the seismological community, providing data and services through the European Integrated Data Archive (EIDA) and the Rapid Raw Strong-Motion (RRSM) database, both integrated in the Observatories and Research Facilities for European Seismology (ORFEUS). The objective of this article is to provide an overview of the KOERI seismic services within ORFEUS and to introduce some of the procedures that allow to check the health of the seismic network and the quality of the data recorded at KOERI seismic stations, which are shared through EIDA and RRSM.

The vibrations of a nonlinear, absorbing soil ground calculation by the method of the seismic microzoning multiple-reflected waves

A nonlinear version of the program ZOND (nonlinear) has been developed based on the dependence of the shear and absorption modulus values on the seismic impact intensity, as well as on the introduction of ratios for calculating various indicators of soil movement (normal stress, deformation, etc.). The program algorithm is based on the multiple-reflected waves theory. An accelerogram of an earthquake, recorded on a rocky ground in Japan with earthquake characteristics similar to those for the territory of Tbilisi (magnitude, epicentral distance, spectral features, etc.), was chosen as an accelerogram set into the bedrock from the generated strong motion database AGESAS. The results of linear and nonlinear calculations with and without absorption are presented. It is clearly seen that with an increase in the intensity of the impact, the nonlinearity manifestation increases. At the same time, absorption increases. In this regard, the resulting movement at very high levels of impact may be below the initial level. This corresponds to the facts known from the analysis of the consequences of strong earthquakes that have occurred in recent years.