Italian strong motion records in ITACA: overview and record processing

The published version 1.0 of the new Italian strong-motion database ITACA (Italian ACcelerometric Archive, ) includes to date (December 2010) about 4,000 three-component waveforms up to M 6.9, from more than 1,800 earthquakes up to 6.9, recorded by about 400 stations in the period 1972–2009. The uncorrected and corrected strong motion data are archived and can be retrieved with their metadata, concerning events, stations and waveforms. The aim of this paper is to present the procedures for processing the records included in ITACA, accounting for the heterogeneity of this data set, both in terms of quality and amplitude of records as well as illustrating the main features of the ITACA strong-motion dataset. Later, we focus on the “exceptional” ground-motion records, that we, conventionally, denote as those having peak acceleration and peak velocity larger than 300 cm/s² and 15 cm/s, respectively. These records are less than 2% of the whole ITACA dataset but they are the most relevant for the seismic hazard and engineering implications. Such large peak values, recorded at distances up to 30 km, are related not only to the strongest Italian earthquakes, but also to events with magnitude down to 4. Furthermore, we investigate the dependence of the largest peak values on horizontal and vertical directions and on source-to-site distance.     

Identification of accelerometric stations in ITACA with distinctive features in their seismic response

In this work, we analyze the records of the Italian strong motion database (ITACA, ) with the aim of identifying stations affected by site effects that are not captured by standard seismic classification schemes. In particular, we consider four different site classifications, two of them based on geological/geophysical characteristics and two driven by data. For each classification we develop a ground motion prediction equation using a random effect approach to isolate the between-station and within-station distribution of errors. The site coefficients obtained for the different classes confirm that site amplification effects are significant for both the horizontal and vertical components. The between-station error normalized to the standard deviation of the between-station error distribution is then used to identify stations characterized by large errors, attributable to site effects not accounted for by the classification schemes. The results show that large errors can affect the predictions when the site effects are not uniquely related to the reduction of the seismic impedance in the uppermost layers. For example, amplifications of ground motion over the long period range are observed for stations installed within alluvial closed-shape basins, as consequence of locally generated surface waves. For these stations, classifications based on the horizontal to vertical response spectra ratio are not reliable, since amplifications are also affecting the vertical component. Another interesting feature which emerges from the analysis is the significant de-amplification of short period spectral ordinates that seems to be related to stations typically set in at the foundation level of massive structures. To increase the usefulness of the data set, the most important distinctive features of the strong motion stations are documented in the ITACA database reports containing the instrument information and the available geological-geotechnical data.     

The recording stations of the Italian strong motion network: geological information and site classification

One of the main objectives of the ITACA (ITalian ACcelerometric Archive) strong motion database, promoted by the Italian Department of Civil Protection, was to improve the characterization of the recording sites from a geological and geophysical point of view and to provide their seismic classification according to the seismic norms pertinent to Italy, namely the Eurocode 8 and the National Technical Norms for Constructions. A standard format to summarize the available information for the recording stations was first produced, in terms of a technical report dynamically linked to the database, i.e., some of the relevant information is automatically updated when the corresponding fields of the database are modified. Then, an important activity of collection, qualification and synthesis of available data was carried out, especially for stations that recorded the strongest earthquakes in Italy in the last 40 years, and for which a relevant number of studies have been published. In spite of this activity, among the more than 700 strong motion stations present in the ITACA database, only a limited number of them could be characterized by quantitative information on subsurface soil properties. For this reason, a dual seismic site classification criterion was implemented, either based on the standard V _s,30 scheme, or, in the absence of such information, based on an expert opinion supported by shallow geology maps, mostly at 1:100,000 scale, and when available on the H/V ratios calculated on recordings. Owing to the relevance in the Italian geographic and morphological context, a special care was also given to the topographic classification of stations, based on suitable criteria developed within a GIS environment.     

Overview of the Italian strong motion database ITACA 1.0

The Italian Strong Motion Database, ITACA, was developed within projects S6 and S4, funded in the framework of the agreements between the Italian Department of Civil Protection (Dipartimento della Protezione Civile, DPC) and the Istituto Nazionale di Geofisica e Vulcanologia (INGV), starting from 2005. The alpha version of the database was released in 2007 and subsequently upgraded to version 1.0 after: (i) including the most recent strong motion data (from 2005 to 2007) recorded in Italy, in addition to the 2008 Parma earthquake, M 5.4, and the M ≥  4.0, 2009 Abruzzo seismic events; (ii) processing the raw strong motion data using an updated procedure; (iii) increasing the number of stations with a measured shear wave velocity profile; (iv) improving the utilities to retrieve time series and ground motion parameters; (v) implementing a tool for selecting time series in agreement with design-response spectra; (vi) compiling detailed station reports containing miscellaneous information such as photo, maps and site parameters; (vii) developing procedures for the automatic generation of station reports and for the updating of the header files. After such improvements, ITACA 1.0 was published at the web site , in 2010. It presently contains 3,955 three-component waveforms, comprising the most complete catalogue of the Italian accelerometric records in the period 1972–2007 (3,562 records) and the strongest events in the period 2008–2009. Records were mainly acquired by DPC through its Accelerometric National Network (RAN) and, in few cases, by local networks and temporary stations or networks. This paper introduces the published version of the Italian Strong Motion database (ITACA version 1.0) together with main improvements and new functionalities.     

Italian strong motion database relative to the period 1972–2004: motivations and aims

The Italian Accelerometic Archive (ITACA) was created in 2007 during a joint project between the Italian Institute for Geophysics and Vulcanology (Istituto Nazionale di Geofisica e Vulcanologia, INGV) and the Italian Civil Protection (Dipartimento della Protezione Civile, DPC). The project, started in 2006, had the aim of filling the data gap of existing strong motion databases and facilitating strong motion data users in obtaining good quality waveforms, through the collection, homogenization and distribution of strong motion data acquired during the period 1972–2004 in Italy by different institutions (Ente Nazionale per l’Energia Elettrica, ENEL, Italian electricity company; Ente per le Nuove tecnologie, l’Energia e l’Ambiente, ENEA, Italian energy and environment organization DPC). The compiled database contains 2,182 three-component waveforms generated by 1,008 earthquakes with a maximum moment magnitude of 6.9 (1980 Irpinia earthquake) and can be accessed on-line at the portal denominated ITACA at the site , where a wide range of search tools enables the user to interactively retrieve events, recording stations and waveforms with particular characteristics, whose parameters can be specified, as needed, through user friendly interfaces. A range of display options allows users to view data in different contexts, extract and download time series and spectral data. This article describes the state of the art up to 2006 and the activities which led to the completion of the project.     

Engineering ground motion record selection in the ITalian ACcelerometric Archive

This paper introduces REXELite, an internet version of REXEL, a software for automatic selection of ground motion suites for nonlinear dynamic analysis of structures. REXELite was developed with the aim of integrating an advanced earthquake records’ repository, such as the ITalian ACcelerometric Archive (ITACA), with a tool to define seismic input for engineering seismic analysis according to international standards (with priority to Europe). In fact, REXELite allows to define target design spectra according either to Eurocode 8 or to the Italian building code, and to search ITACA for suitable sets of seven records (comprised of one or two horizontal ground motion components) matching such target spectra: on average, in a user-specified period range, and with the desired tolerance. The records in the set also have, individually and according to some criteria, the most similar spectral shape with respect to that of the code. Selection options include magnitude, source-to-site distance, soil conditions and, if desired, linear scaling of records to reduce further record-to-record variability of the selected suite.     

The ITalian ACcelerometric Archive (ITACA): processing of strong-motion data

The Italian strong-motion database was created during a joint project between Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italian Institute for Geophysics and Vulcanology) and Dipartimento della Protezione Civile (DPC, Italian Civil Protection). The aim of the project was the collection, homogenization and distribution of strong motion data acquired in Italy in the period 1972–2004 by different institutions, namely Ente Nazionale per l’Energia Elettrica (ENEL, Italian electricity company), Ente per le Nuove tecnologie, l’Energia e l’Ambiente (ENEA, Italian energy and environment organization) and DPC. Recently the strong-motion data relative to the 23th December 2009, Parma (Mw = 5.4 and Mw = 4.9) and to the April 2009 L’Aquila sequences (13 earthquakes with 4.1 ≤ Mw ≤ 6.3) were included in the Italian Accelerometric Archive (ITACA) database (beta release). The database contains 7,038 waveforms from analog and digital instruments, generated by 1.019 earthquakes with magnitude up to 6.9 and can be accessed on-line at the web site . The strong motion data are provided in the unprocessed and processed versions. This article describes the steps followed to process the acceleration time series recorded by analogue and digital instruments. The procedures implemented involve: baseline removal, instrumental correction, band pass filtering with acausal filters, integration of the corrected acceleration in order to obtain velocity and displacement waveforms, computation of acceleration response spectra and strong motion parameters. This procedure is applied to each accelerogram and it is realised to preserve the low frequency content of the records.     

A review of the activity of two accelerometric networks in Basilicata (Italy)

The Basilicata region (Italy) is affected by the intense seismic activity of the Apenninic Chain. Since 1998 the University of Basilicata and the Institute of Methodologies for Environmental Analysis (IMAA-CNR) started a multi-parametric geophysical monitoring including seismometers and accelerometers. The 1996 marked the initial deployment of the Civil Protection of Province of Potenza accelerometric network with permanent real-time link since 2006. In 2003, the Basilicata regional government started a microzonation project that allowed the University and IMAA-CNR to manage a mobile accelerometric network and to redesign the permanent seismic and accelerometric network. This paper reviews the main results achieved so far, the data that will be contributed to ITACA (the Italian Accelerometric network) and the future developments of the two networks.     

EES-GIS系统及其在九江-瑞昌地震中的应用

叙述了EES—GIS应急数据库系统的技术思路、组成及其功能,介绍了该系统在九江地震应急中的应用效果。实践表明,EES—GIS系统在地震应急辅助决策中能有效地提高评估效率。     

Extensive characterization of Italian accelerometric stations from single-station ambient-vibration measurements

This paper describes the analyses of the single-station ambient-vibration measurements performed on the Italian accelerometric network to detect site resonance phenomena potentially affecting earthquake recordings. The use of low cost, high quality microtremor measurement can be helpful to discriminate among soil classes, since several classification schemes based on resonance frequencies were proposed in the last decades. Operatively, in the framework of the Italian Strong Motion Database project (DPC-INGV 2007–2009 S4; ), soil resonance frequencies have been evaluated from more than 200 ambient vibration measurements in correspondence of accelerometric stations included in ITACA (). The noise recordings have been analyzed using the same numerical protocol in order to standardize the results. Particular attention has been paid to evaluate the quality of measurements and to develop an on-purpose mathematical tool to automatically estimate the peaks in the horizontal-to-vertical spectral ratio (HVSR) curve. The reliability of the resonance frequencies from HVSR has been tested by comparing estimates provided by independent methods (modeling or earthquake recordings). The test confirmed the reliability of the microtremor HVSR for assessing the resonance frequencies of the examined sites.     

AGrav—The New International Absolute Gravity Database of BGI and BKG and its benefit for the Global Geodynamics Project (GGP)

A new database for absolute gravity (AG) measurements has been implemented at BGI and BKG and is operational now for storing absolute gravity data either in the form of metadata or as detailed measurement results. The database development was proposed by the IGFS (International Gravity Field Service) and is expected to have a great importance for the GGOS (Global Geodetic Observing System) initiative. This database will provide an overview about AG stations and observations and by this improve the cooperation between gravity groups and foster the combination with other geodetic observation techniques. The international community of absolute gravimeter users is asked to contribute to this database.In addition to its primary purposes, demonstration of the global site distribution and information about available observations, the database could also provide an important contribution to the Global Geodynamics Project (GGP). Precise repeated absolute gravity measurements at the superconducting gravimeter (SG) sites are necessary for the determination of SG drift parameters and can be used for checking SG instrument calibration factors. The AGrav database is capable of storing the necessary AG observations at the SG location in detail up to the “single drop level” and provides this information for the combination with SG time series. An example for a selected station is presented. It is proposed to establish an interface between the AGrav and GGP databases.     

Horizontal and vertical ground motion prediction equations derived from the Italian Accelerometric Archive (ITACA)

A set of Ground Motion Prediction Equations (GMPEs) for the Italian territory is proposed, exploiting a new strong-motion data set become available since July 2007 through the Italian Accelerometric Archive (ITACA). The data set is composed by 561 three-component waveforms from 107 earthquakes with moment magnitude in the range 4.0–6.9, occurred in Italy from 1972 to 2007 and recorded by 206 stations at distances up to 100 km. The functional form used to derive GMPEs in Italy (Sabetta and Pugliese in Bull Seismol Soc Am 86(2):337–352, 1996) has been modified introducing a quadratic term for magnitude and a magnitude-dependent geometrical spreading. The coefficients for the prediction of horizontal and vertical peak ground acceleration, peak ground velocity and 5% damped acceleration response spectra are evaluated. This paper illustrates the new data set, the regression analysis and the comparisons with recently derived GMPEs in Europe and in the Next Generation Attenuation of Ground Motions (NGA) Project.     

SQLite在地震前兆数据汇集器中的应用

首先概述地震前兆数据汇集器的软硬件体系结构及使用嵌入式数据库的优越性,进而介绍简洁实用的嵌入式数据库SQLite,并搭建平台进行可行性测试与论证,为地震前兆数据汇集器应用嵌入式数据库提供依据。     

Adaptive Training of Neural Networks for Automatic Seismic Phase Identification

—?A neural network module has been implemented in the Prototype International Data Centre (PIDC) for automated identification of the initial phase type of seismic detections. Initial training of the neural networks for stations of the International Monitoring System (IMS) requires considerable effort. While there are many seismic phases in the analyst-reviewed database that can be assumed as the ground-truth resource of the initial phase type of Teleseism (T), Regional P (P), and Regional S (S), no ground-truth database of noise (N) is available. To reduce analyst effort required in building a ground-truth database, an “Adaptive Training Approach” is proposed in this paper. This approach automatically selects training patterns to take advantage of the learning ability of neural networks and information on the accumulated observation database. Using this approach, neural networks were trained on the data provided by station STKA, Australia. The performance of automated phase identification has been improved significantly by the retrained neural networks. This approach is also validated by comparison with the performance using the ground-truth noise database.     

Development of an Information and Database System for the IERS: Status and outlook

The focus of this paper is to present the concepts for a new dynamic, i.e. database-driven information system for the International Earth Rotation and Reference Systems Service (IERS). Its goal is to coordinate the data and information flow between the participating institutions. Therefore, all relevant data and products of the IERS should be archived to guarantee their long-term availability. At the same time the consistency and timeliness of the contents of the information system can be guaranteed by managing the information in a database. Additionally, the metadata of all products (including the IERS publications) should be modelled in a database to allow the users to search for specific data or topics with respect to space, time and content. In order to be able to link related data the heterogeneous formats of the products have to be transformed into a common format. The eXtensible Markup Language (XML) is going to be used, to perform this ambitious task. The usage of XML not only allows to link related data but also to easily exchange data and to present them in different ways like Web pages, pdf, etc. The system will be completed by several tools to manage and coordinate the tasks of the Central Bureau (CB) and by an information system with respect to IERS-related topics. The standardised database tools will also allow an easy exchange of information with and links to other databases within the IGGOS project to realize a powerful instrument to serve the Earth observing system.     

Database system for deep seismic sounding

A new technique to handle massive geophysical data has been developed with the aid of database in last decade. In this paper, we describe briefly the formation of deep seismic sounding database, the functions of the database management system, and the current research situation on this technique in China. The database is based on the Chinese version of the relational database management software package named FoxBase. The established database shows the features of low redundancy, and high data-sharing, independence and integrity. Its management system has advantages of high efficiency and convenience. This database can further be upgraded to a database for all kinds of deep geophysical methods.     

Database system for deep seismicsounding

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General database for ground water site information

In most cases, analysis and modeling of flow and transport dynamics in ground water systems require long-term, high-quality, and multisource data sets. This paper discusses the structure of a multisite database (the H+ database) developed within the scope of the ERO program (French Environmental Research Observatory, http://www.ore.fr). The database provides an interface between field experimentalists and modelers, which can be used on a daily basis. The database structure enables the storage of a large number of data and data types collected from a given site or multiple-site network. The database is well suited to the integration, backup, and retrieval of data for flow and transport modeling in heterogeneous aquifers. It relies on the definition of standards and uses a templated structure, such that any type of geolocalized data obtained from wells, hydrological stations, and meteorological stations can be handled. New types of platforms other than wells, hydrological stations, and meteorological stations, and new types of experiments and/or parameters could easily be added without modifying the database structure. Thus, we propose that the database structure could be used as a template for designing databases for complex sites. An example application is the H+ database, which gathers data collected from a network of hydrogeological sites associated with the French Environmental Research Observatory.     

基于GIS的长江三峡水库诱发地震预测数据库构建

从系统需求分析出发 ,介绍了可视化的长江三峡水库诱发地震预测数据库构建的主要内容及其实施技术路线 ,划分了国内外典型的诱震震例以及长江三峡地区基础地理、诱震地质环境和诱发地震前兆监测等相关基础信息的主要类型 ,确定了各类信息的数据库结构和数据格式。在此基础上 ,对各类基础图形进行数字化处理 ,建立了可视化的图形数据库 ;通过其相关属性信息的录入或转换 ,建立了各类图形相应的属性数据库 ;利用GIS技术 ,对图形数据库及其属性数据库进行了无缝集成 ,实现了图形数据与其相应属性数据间的可视化交互式查询、浏览、管理和分析     

福建水位观测网对印度尼西亚8级巨震的响应特征分析

分析了福建水位观测网对2004年和2005年2次印度尼西亚（以下简称印尼）8级巨震的响应情况,结果表明福建水位观测网能够记录和反映远大地震事件,响应的时间分布、空间展布、幅度大小、变化形态均同构造密切相关;同时指出,水井对远震的响应特征不但同水井的构造位置有关,还同水井的井孔结构、水文地质条件等因素有关。现有的数据库应进一步完善,增加水井的井孔结构、构造地质、水文地质等基础背景资料,才能更好地进行地震监测。