淮阴台井下测震震级偏差初探

依据台站两年来实测的地震震级和江苏省区域测震台网定的震级进行比较,计算出各个地震的偏差值和台站的震级校正值,并获得相应的标准误差,最后对影响震级差值因素进行了探讨。     

Effects of supplemental viscous damping on seismic response of asymmetric-plan systems

Coupling between lateral and torsional motions may lead to much larger edge deformations in asymmetric-plan systems compared to systems with a symmetric plan. Supplemental viscous damping has been found to be effective in reducing deformations in the symmetric-plan system. This investigation examined how supplemental damping affects the edge deformations in asymmetric-plan systems. First, the parameters that characterize supplemental viscous damping and its plan-wise distribution were identified, and then the effects of these parameters on edge deformations were investigated. It was found that supplemental damping reduces edge deformations and that reductions by a factor of up three are feasible with proper selection of system parameters. Furthermore, viscous damping may be used to reduce edge deformations in asymmetric-plan systems to levels equal to or smaller than those in the corresponding symmetric-plan system. © 1998 John Wiley & Sons, Ltd.     

Hazard-consistent earthquake scenarios

Earthquake-resistant design and seismic analysis often require the earthquake action to be represented in the form of acceleration time-histories. Real accelerograms can be selected based on matching an earthquake scenario, defined by magnitude and distance, and scaled if necessary. The scaled accelerograms should reflect the hazard in terms of the parameters that characterise the inelastic demand on structures, including response spectral ordinates, duration and energy content. In order to maintain realistic ground motions, the scaling factors should not differ greatly from unity. It is found that in many cases, where the hazard is influenced by more than one seismic source, it is impossible to define a single earthquake scenario that is compatible with the results of probabilistic seismic hazard assessment. Even if a hazard-consistent scenario can be defined, there are difficulties encountered in using the results to select and scale real accelerograms.     

Expanding the possibilities of two-dimensional multielectrode systems, with consideration to earlier geoelectric arrays

Recent two-dimensional multielectrode measurements are restricted to only a few geoelectric arrays. Realizing that specific features of nearly 90 other arrays are totally ignored, all original intentions as published about the development of new geoelectric arrays were reviewed. Apart from arrays, either already applied in two-dimensional geoelectric arrays or impossible to be applied in such systems, 61 forgotten once-developed arrays were found. These provide altogether 102 various solutions, which would be able to increase the efficiency of two-dimensional multielectrode measurements in some respect. 46 array solutions are able to enhance the depth of investigation; 9/11 array solutions give better vertical/horizontal resolution; 17 array solutions provide better planview images; 8 array solutions are worth applying in areas with limited access; 11 array solutions may reduce the effect of near-surface inhomogeneities. By reviving these forgotten arrays, it will be possible to develop versatile multielectrode systems, which are more adaptive to the diverse field needs.     

Upper crustal structure under Jingtai–Hezuo profile in Northeastern Tibet from topography-dependent eikonal traveltime tomography

The Northeastern Tibetan plateau records Caledonian Qilian orogeny and Cenozoic reactivation by continental collision between the Indian and Asian plates. In order to provide the constraint on the Qilian orogenic mechanism and the expansion of the plateau, wide-angle seismic data was acquired along a 430 km-long profile between Jingtai and Hezuo. There is strong height variation along the profile, which is dealt by topography flattening scheme in our crustal velocity structure reconstruction. We herein present the upper crustal P-wave velocity structure model resulting from the interpretation of first arrival dataset from topography-dependent eikonal traveltime tomography. With topography flattening scheme to process real topography along the profile, the evenness of ray coverage times of the image area (upper crust) is improved, which provides upper crustal velocity model comparable to the classic traveltime tomography (with model expansion scheme to process irregular surface). The upper crustal velocity model shows zoning character which matches with the tectonic division of the Qaidam-Kunlun-West Qinling belt, the Central and Northern Qilian, and the Alax blocks along the profile. The resultant upper crustal P-wave velocity model is expected to provide important base for linkage between the mapped surface geology and deep structure or geodynamics in Northeastern Tibet.     

广西大厂矿区地震台网技术系统设计

金属矿区开采活动所引起的地质体强度弱化,并产生矿震灾害已引起政府和企业的重视。介绍了全国首个金属矿区地震台网技术系统设计指导思想、台网布局及主要技术指标,以及提出建设矿山地震台网的作用及意义。     

鄂尔多斯盆地北缘南北向剖面上地幔远震P波层析成像

为深入理解华北克拉通破坏机理,本研究通过鄂尔多斯盆地北缘南北向宽频带线性高密度流动地震台观测记录的远震波形数据,获得了1985条高质量到时资料,进而利用FMTT(Fast Marching Teleseismic Tomography)快速行进层析成像方法获得了华北克拉通西部鄂尔多斯盆地北缘深至300 km范围的P波速度模型.结果显示,鄂尔多斯盆地下方呈现出深至150~200 km的高波速异常,说明华北克拉通其西部岩石圈保存完好尚未遭到明显破坏.河套地堑下方存在向鄂尔多斯盆地下方延伸的明显低波速异常,其深度可达300 km深度,而阴山造山带下方上地幔存在深至100 km左右的弱高波速异常,说明鄂尔多斯盆地周边地区的岩石圈均遭到一定程度破坏并减薄,可能与新生代时期太平洋板块的俯冲引起深部热物质上涌等作用密切相关.这些研究结果说明,华北克拉通在构造演化过程中不同块体经历了不同的破坏演化历史,这对于认识克拉通破坏减薄机制具有重要意义.     

SIMPLE PUSH-OVER ANALYSIS OF ASYMMETRIC BUILDINGS

A simple method for the non-linear static analysis of complex building structures subjected to monotonically increasing horizontal loading (push-over analysis) is presented. The method is designed to be a part of new methodologies for the seismic design and evaluation of structures. It is based on the extension of a pseudo-three-dimensional mathematical model of a building structure into the non-linear range. The structure consists of planar macroelements. For each planar macroelement, a simple bilinear or multilinear base shear–top displacement relationship is assumed. By a step-by-step analysis an approximate relationship between the global base shear and top displacement is computed. During the analysis the development of plastic hinges throughout the building can be monitored. The method has been implemented into a prototype computer program. In the paper the mathematical model, the base shear–top displacement relationships for different types of macroelements, and the step-by-step computational procedure are described. The method has been applied for the analysis of a symmetric and an asymmetric variant of a seven-storey reinforced concrete frame–wall building, as well as for the analysis of a complex asymmetric 21-storey reinforced concrete wall building. The influence of torsion on structural behaviour is discussed. © 1997 by John Wiley & Sons, Ltd.     

Delineation of Potential Seismic Source Regions of Moderately Strong Earthquakes Without Seismogenic Tectonics

In this paper,approaches are developed to delineate the potential seismic source regions of moderately strong earthquakes that do not have clear seismotectonic settings.Based on comprehensive analysis of regional tectonic backgrounds and seismicity,the data,such as isoseisrnals,spatial distribution of after shocks,regional tectonic stress field,and focal mechanisms,are employed for the delineation of the potential seismic source regions.The reliability of such potential seismic source regions is also discussed.     

苏门答腊Ms8.7级大震前的地脉动预警信息

介绍了辽宁数字台网运行的脉动异常跟踪系统(RTTS),叙述了这个系统在2004年12月26日08时58分55.2秒印尼苏门答腊西北近海(北纬3.9,东经95.9)8.7级地震前,营口、锦州台地脉动波形的幅度和周期明显异常的情况。并展现了利用RTTS系统进行地脉动研究的前景。