Response spectral relationships for rock sites derived from the component attenuation model

The seismological model was developed initially from the fundamental relationship between earthquake ground motion properties and the seismic moment generated at the source of the earthquake. Following two decades of continuous seismological research in the United States, seismological models which realistically account for both the source and path effects on the seismic shear waves have been developed and their accuracy rigorously verified (particularly in the long and medium period ranges). An important finding from the seismological research by Atkinson and Boore and their co‐investigators is the similarity of the average frequency characteristics of seismic waves generated at the source between the seemingly very different seismic environments of Eastern and Western North America (ENA and WNA, respectively). A generic definition of the average source properties of earthquakes has therefore been postulated, referred to herein as the generic source model. Further, the generic ‘hard rock’ crustal model which is characteristic of ENA and the generic ‘rock’ crustal model characteristic of WNA have been developed to combine with the generic source model, hence enabling simulations to be made of the important path‐related modifications to ground motions arising from different types of crustal rock materials. It has been found that the anelastic contribution to whole path attenuation is consistent between the ENA and WNA models, for earthquake ground motions (response spectral velocities and displacements) in the near and medium fields, indicating that differences in the ENA and WNA motions arise principally from the other forms of path‐related modifications, namely the mid‐crust amplification and the combined effect of the upper‐crust amplification and attenuation, both of which are significant only for the generic WNA ‘rock’ earthquake ground motions. This paper aims to demonstrate the effective utilization of the latest seismological model, comprising the generic source and crustal models, to develop a response spectral attenuation model for direct engineering applications. The developed attenuation model also comprises a source factor and several crustal (wave‐path modification) component factors, and thus has also been termed herein the component attenuation model (CAM). Generic attenuation relationships in CAM, which embrace both ENA and WNA conditions, have been developed using stochastic simulations. The crustal classification of a region outside North America can be based upon regional seismological and geological information. CAM is particularly useful for areas where local strong motion data are lacking for satisfactory empirical modelling. In the companion paper entitled ‘response spectrum modelling for rock sites in low and moderate seismicity regions combining velocity, displacement and acceleration predictions’, the CAM procedure has been incorporated into a response spectrum model which can be used to effectively define the seismic hazard of bedrock sites in low and moderate seismicity regions. This paper and the companion paper constitute the basis of a long‐term objective of the authors, to develop and effectively utilize the seismological model for engineering applications worldwide.     

Monitoring of the Arctic region: contribution of the Arkhangelsk seismic network

We evaluate the contribution of the Arkhangelsk seismic network to the recording of seismic events of the Arctic region. The evaluation is performed by means of the general analysis of the network seismic catalog, evaluation of the magnitude sensitivity, and comparative analysis of the Arkhangelsk network catalogs with NORSAR seismological data services and the Geophysical Service of the Russian Academy of Sciences. It is established that the Arkhangelsk network has a rather high sensitivity and records the intra-plate and inter-plate seismic activity in the Arctic Region. Due to the start of the seismic station operation on the Franz Josef Land Archipelago, there is a capability to record earthquakes, data on which are missing in the catalogs of well-known seismological data services.     

GIS as a Tool for Seismological Data Processing

—?A computerized application of an integrated seismological GIS model is presented. An object oriented approach of the GIS topology is introduced and the special functions and features of this system are described. A network topology was selected to simulate the network characteristics of seismological data management and analysis. Each seismological entity is considered as a graphical data object, which is associated to other objects by predefined relationships. The graphical user interface introduced by GIS enables to handle seismological software routines and data in a more intuitive way. Examples of interactive processing of seismic waveforms for detecting, locating and characterizing seismic events using GIS visualization capabilities are presented. The benefits of this system during a passive seismic survey in the framework of the CTBT are highlighted.     

K-means cluster analysis and seismicity partitioning for Pakistan

Pakistan and the western Himalaya is a region of high seismic activity located at the triple junction between the Arabian, Eurasian and Indian plates. Four devastating earthquakes have resulted in significant numbers of fatalities in Pakistan and the surrounding region in the past century (Quetta, 1935; Makran, 1945; Pattan, 1974 and the recent 2005 Kashmir earthquake). It is therefore necessary to develop an understanding of the spatial distribution of seismicity and the potential seismogenic sources across the region. This forms an important basis for the calculation of seismic hazard; a crucial input in seismic design codes needed to begin to effectively mitigate the high earthquake risk in Pakistan. The development of seismogenic source zones for seismic hazard analysis is driven by both geological and seismotectonic inputs. Despite the many developments in seismic hazard in recent decades, the manner in which seismotectonic information feeds the definition of the seismic source can, in many parts of the world including Pakistan and the surrounding regions, remain a subjective process driven primarily by expert judgment. Whilst much research is ongoing to map and characterise active faults in Pakistan, knowledge of the seismogenic properties of the active faults is still incomplete in much of the region. Consequently, seismicity, both historical and instrumental, remains a primary guide to the seismogenic sources of Pakistan. This study utilises a cluster analysis approach for the purposes of identifying spatial differences in seismicity, which can be utilised to form a basis for delineating seismogenic source regions. An effort is made to examine seismicity partitioning for Pakistan with respect to earthquake database, seismic cluster analysis and seismic partitions in a seismic hazard context. A magnitude homogenous earthquake catalogue has been compiled using various available earthquake data. The earthquake catalogue covers a time span from 1930 to 2007 and an area from 23.00° to 39.00°N and 59.00° to 80.00°E. A threshold magnitude of 5.2 is considered for K-means cluster analysis. The current study uses the traditional metrics of cluster quality, in addition to a seismic hazard contextual metric to attempt to constrain the preferred number of clusters found in the data. The spatial distribution of earthquakes from the catalogue was used to define the seismic clusters for Pakistan, which can be used further in the process of defining seismogenic sources and corresponding earthquake recurrence models for estimates of seismic hazard and risk in Pakistan. Consideration of the different approaches to cluster validation in a seismic hazard context suggests that Pakistan may be divided into K?=?19 seismic clusters, including some portions of the neighbouring countries of Afghanistan, Tajikistan and India.     

The recently compiled Turkish strong motion database: preliminary investigation for seismological parameters

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.     

Seismic hazard in the Northwestern Apennines

A study of the seismic hazard for the Northwestern Apennines, based on seismotectonic and seismicity data, is presented. Starting from a seismotectonic analysis, showing the complex structural evolution of the region, the seismic activity in the period 1000–1975 has been modeled by some seismic source zones justified by geostructural and seismological considerations. The recurrence statistical parameters and the attenuation laws have been determined for all these sources. With an appropriate analysis method, maps of seismic hazard for return periods of 50, 200, and 500 years were elaborated. Finally, a comparison with the map of maximum felt intensity and with hazard values calculated by a different approach is presented.     

Full-Wave Seismic Data Assimilation: Theoretical Background and Recent Advances

The seismological inverse problem has much in common with the data assimilation problem found in meteorology and oceanography. Using the data assimilation methodology, I will formulate the seismological inverse problem for estimating seismic source and Earth structure parameters in the form of weak-constraint generalized inverse, in which the seismic wave equation and the associated initial and boundary conditions are allowed to contain errors. The resulting Euler?CLagrange equations are closely related to the adjoint method and the scattering-integral method, which have been successfully applied in full-3D, full-wave seismic tomography and earthquake source parameter inversions. I will review some recent applications of the full-wave methodology in seismic tomography and seismic source parameter inversions and discuss some challenging issues related to the computational implementation and the effective exploitation of seismic waveform data.     

澳门地区建筑物设计地震动参数研究

根据澳门地区地震环境、场地特点,利用本地区的工程地质钻孔资料和相似地区的场地设计地震动参数研究成果,结合少量工程地震钻孔剖面的土层反应分析结果,合理地确定了澳门地区不同建筑场地类别的设计地震动参数,对于Ⅱ、Ⅲ类场地,按存在或不存在成片淤泥两种情况进行了反应谱特征周期参数分组,为澳门地区一般建筑工程的抗震设计提供了参考依据。     

Deterministic Seismic Scenarios for Imphal City

In this article, the spatial variation of ground motion in Imphal City has been estimated by the finite-fault seismological model coupled with site response analysis. The important seismic sources around Imphal City have been identified from the fault map and past seismicity data. The rock level acceleration time histories at Imphal City for the 1869 Cachar (M_w 7.5) earthquake and a hypothetical M_w 8.1 event in the Indo-Burma subduction zone have been estimated by a stochastic finite-fault model. Soil investigation data of 122 boreholes have been collected from several construction projects in Imphal City. Site response analysis has been carried out and the surface level ground motion has been determined for Imphal City for these two earthquake events. The results are presented in the form of peak ground acceleration (PGA) contour map. From the present study it has been ascertained that the maximum amplification for PGA over Imphal City is as high as 2.5. The obtained contour maps can serve as guidelines for identifying vulnerable areas and disaster mitigation in Imphal City.     

辽宁省数字化地震前兆数据库的建立

地震前兆数据一直是地震分析预报必不可少的重要数据资源。随着辽宁省地震前兆台站数字化技术改造的开展，地震前兆模拟记录将逐步被数字化记录所取代。我们结合数字化技术改造的实际情况，采用先进的网络关系数据库模型构造了辽宁省数字地震前兆数据库。该数据库直接面向整个地震系统，为地震预报提供详实的数据服务和先进的研究手段。本文对数据库系统、数据库总体设计及数据共享服务也进行了深入研究和讨论。     

HNS.BAS软件在地震观测报告数据处理中的应用

HNS．BAS是一个地震数据处理软件，用于把地震数据处理成中国地震局要求的地震观测报告。此软件在输入地震数据时，操作便捷，并具有多种数据处理功能，最后自动生成地震观测报告。     

Seismic Microzonation: A Comparison between Geotechnical and Seismological Approaches in Pointe-à-Pitre (French West Indies)

Pointe-à-Pitre, the main city of Guadeloupe in the French West Indies, has on several occasions been partially destroyed by major historical earthquakes. Moreover, a post-seismic assessment of the damage from the 1985 Montserrat earthquake indicates that the town is prone to site effects. Consequently, from 1996 to 1998, BRGM conducted a seismic microzonation study based on geotechnical and geological data. At the same time, three seismological studies were being conducted – two based on earthquake recordings using a time-series analysis and the classical spectral ratio (CSR) method (CETE/LCPC and BRGM), and the third based on noise measurement at 400 points using the horizontal-to-vertical noise ratio (HVNR) method (CETE/LCPC). The objective of this paper is not to carry out a new microzonation study by taking into account all the results, but rather to show in what respects the results of these different methods are in agreement or not. A comparison of the results of the seismological studies with the geotechnical microzonation shows that they are in fairly good agreement, albeit with some discrepancies. The results indicate that the seismological methods and the geotechnical data are highly complementary and should be used together in compiling seismic transfer-function microzonation maps. This revised version was published online in July 2006 with corrections to the Cover Date.     

单台数字化地震监测系统在地方地震工作中的应用

广州市番禺区地层办公室在全国地方地层工作部门范围内，首先建成了一套单台数字化地层监测系统——TDS单台数字化地震监测处理系统，提高了番禺及其邻近地区的地层监测能力，为政府快速反应提供依据，并配合其他职能部门，在地震应急、解决因爆破引起的纠纷和地震科普宣传等方面得到了很好的应用。     

Ground motion modelling in Tehran based on the stochastic method

This paper presents the development of a seismological model for the Tehran area. This modelling approach, which was originally developed in Eastern North America, has been used successfully in other parts of the world including Australia and China for simulating accelerograms and elastic response spectra. Parameters required for input into the model were inferred from seismological and geological information obtained locally. The attenuation properties of the earth crust were derived from the analysis of accelerogram records that had been collated from within the region in a previous study. In modelling local modifications of seismic waves in the upper crust, shear-wave velocity profiles have been constructed in accordance with the power law. Information inferred from micro-zonation studies (for near-surface conditions) and from measurements of teleseismic P-waves reflected from the deeper crusts as reported in the literature has been used to constrain parameters in the power-law relationships. This method of obtaining amplification factors for the upper crust distinguishes this study from earlier studies in the Tehran area (in which site amplification factors were inferred from the H/V ratio of the recorded ground motions). The regional specific seismological model so constructed from the study enabled accelerograms to be simulated and elastic response spectra calculated for a series of magnitude–distance combinations. Importantly, elastic response spectra calculated from the simulated accelerograms have been compared with those calculated from accelerograms recorded from earthquakes with magnitudes ranging between M6.3 and M7.4. The peak ground velocity values calculated from the simulated accelerograms have also been correlated with values inferred from macro-seismic intensity data of 17 historical earthquakes with magnitudes varying between 5.4 and 7.7 and with distances varying between 40 and 230 km. This paper forms part of the long-term strategy of the authors of applying modern techniques for modelling the attenuation behaviour of earthquakes in countries which are lacking in instrumental data of earthquakes.     

基于网络的数字地震台网数据处理系统设计

基于网络的数字地震台网数据处理系统(EDSP_NET)是根据区域数字地震台网在宽频带数据处理、 数据共享方面的需求开发的。 EDSP_NET运行于Windows平台, 用于汇集、 处理来自数字地震台站的波形数据, 实现台网中心间的数据共享, 监视台站和台网中心处理系统的运行状态。 详细介绍了系统结构和功能, 并简要介绍了系统的三个应用模式。     

Seismic activation of tectonic stresses by mining

Hard coal mining in the area of the Bytom Syncline (Upper Silesia Coal Basin, Poland) has been associated with the occurrence of high-energy seismic events (up to 10⁹ J; local magnitude up to 4.0), which have been recorded by the local mining seismological network and regional seismological network. It has been noticed that the strongest seismic events occur when the mine longwall alignments coincide with the syncline axis. Data recorded by the improved local seismic network in the Bobrek Mine allow the estimation of the depths of the events’ hypocentres during excavation of longwall panel 3 as it approached the syncline axis. The recorded data were also used to estimate the location of the rupture surface and stress distribution in the seismic focus region. It was concluded that tectonic stresses, particularly horizontal stress components, are essential in the distribution of seismic tremors resulting from reverse faulting. The stresses induced by mining activity are only triggering tectonic deformations. The hypocentres of the strongest seismic events during mining of longwall panel 3/503 were located 300–800 m deeper than the level of coal seam 503.     

山西大同数字遥测地震台网技术系统的建设

叙述了山西大同数字遥测地震台网的结构及监测能力，台网的功能及技术指标和遥测台技术系统、供电系统、中心系统、避雷系统、中继站、信道等的建设情况，分析了山西大同数字遥测地震台网考核运行期间获得的资料，结果表明，大同数字遥测地震台网在检测地震能力、动态范围、地震处理精度和速度方面优于模拟台网，对网内大部分区域及东部网缘区域的地震监控能力可达1.5级，网内地震响应速度小于10min，得出该台风可为地学研究及地震预报提供更为丰富的数字地震资料的结论。     

地震震相分析与测量的进展

地震震相分析是地震学研究中最基本、也是最基础的工作。本文就震相分析与测量方面的一些重要进展进行了概述,主要包括初动到时和极性的测量,震相中其他参数的测量,以及其他震相的识别与测量等。本文还着重介绍了《IASPEI标准地震震相表》,该震相表的完成与公布是地震震相分析工作的重要进展。     

An attenuation model for distant earthquakes

Large magnitude earthquakes generated at source–site distances exceeding 100km are typified by low‐frequency (long‐period) seismic waves. Such induced ground shaking can be disproportionately destructive due to its high displacement, and possibly high velocity, shaking characteristics. Distant earthquakes represent a potentially significant safety hazard in certain low and moderate seismic regions where seismic activity is governed by major distant sources as opposed to nearby (regional) background sources. Examples are parts of the Indian sub‐continent, Eastern China and Indo‐China. The majority of ground motion attenuation relationships currently available for applications in active seismic regions may not be suitable for handling long‐distance attenuation, since the significance of distant earthquakes is mainly confined to certain low to moderate seismicity regions. Thus, the effects of distant earthquakes are often not accurately represented by conventional empirical models which were typically developed from curve‐fitting earthquake strong‐motion data from active seismic regions. Numerous well‐known existing attenuation relationships are evaluated in this paper, to highlight their limitations in long‐distance applications. In contrast, basic seismological parameters such as the Quality factor (Q‐factor) could provide a far more accurate representation for the distant attenuation behaviour of a region, but such information is seldom used by engineers in any direct manner. The aim of this paper is to develop a set of relationships that provide a convenient link between the seismological Q‐factor (amongst other factors) and response spectrum attenuation. The use of Q as an input parameter to the proposed model enables valuable local seismological information to be incorporated directly into response spectrum predictions. The application of this new modelling approach is demonstrated by examples based on the Chi‐Chi earthquake (Taiwan and South China), Gujarat earthquake (Northwest India), Nisqually earthquake (region surrounding Seattle) and Sumatran‐fault earthquake (recorded in Singapore). Field recordings have been obtained from these events for comparison with the proposed model. The accuracy of the stochastic simulations and the regression analysis have been confirmed by comparisons between the model calculations and the actual field observations. It is emphasized that obtaining representative estimates for Q for input into the model is equally important.Thus, this paper forms part of the long‐term objective of the authors to develop more effective communications across the engineering and seismological disciplines. Copyright © 2003 John Wiley & Sons, Ltd.     

山东数字化水位观测资料与模拟观测资料的对比分析

山东数字化水位观测开展了近3年时间，与模拟观测相比，具有数据传输快、数据量级大、人为误差少的优点，从而使地下水位的高频、短周期信息大量增加，为捕捉地震短临异常信息提供了有利条件。分析结果表明，数字化水位观测资料与模拟观测资料的变化特征一致，因而可以代替现有的模拟观测；数字化水位观测资料保存在SQLserver数据库，可通过地震前兆信息处理与软件系统（EIS2000）方便地联接，随时采用相关的数学处理方法分析，跟踪动态的发展变化；日常分析应用表明，数字化水位观测资料仍可延用以往模拟观测资料的分析处理方法，同时许多新方法（如潮汐分析、加卸载响应比法）也可在数字化水位观测资料分析中应用。