从土耳其地震看强震与活动断层的关系

在本文中，我们讨论了土耳其强震与活动断层的关系。结果表明，二者之间关系密切。因此，对活动断层进行更多、更深入的探测和研究，对地震预报和其它防震减灾工作是十分必要和有益的。     

编者按

随着地震研究的深入、地震预测水平的提高及“十五”计划的逐步启动 ,为更好地做好防震减灾工作 ,必须加强科学研究、制定地震预测科学发展规划 ,提高其预测水平 ,中国地震局分析预报中心科学技术委员会决定在《地震》期刊上开辟“专家论坛”。期望通过该“栏目”,为地震系统及有关单位的领导、科研人员和科技管理人员更多地了解我国地震科技的发展历史 ,认识当前的防震减灾科学研究水平提供参考 ,以便总结过去 ,面向未来 ,更好地推进新世纪的地震科技发展。本专栏拟请国内外相关领域有识志士、专家、院士等学者不拘形式、各抒己见 ,每期刊…     

强震动观测仪器面临的机遇和挑战

本文介绍了国内外强震仪、力平衡加速度计、烈度计、MEMS加速度仪等强震动观测仪器的发展历史与现状,概述了强震动记录中典型异常波形产生的原因和力平衡加速度计的仪器响应误差及校正,建议了解决强震仪器缺陷的措施,分析了强震仪在强震动观测发展中面临的机遇和挑战。研究结果如下:① 进行强震动记录异常波形的研究是有针对性改进现有强震仪存在问题的很好途径;② 早期数字强震仪（力平衡加速度计频带范围0至30Hz）获取的强震动记录应进行仪器校正;③ 应跟踪强震动观测新方法和相关领域新技术,发展MEMS加速度仪和光纤加速度仪等新型仪器。     

前兆台网遥控供电仪的设计

介绍了前兆台网遥控供电仪的设计思路和设计技术，就该遥控仪可实现的功能进行了描述，给出了遥控仪的技术指标和应用图例。该遥控仪可以满足遥测台站供电控制的需要。     

陶赖昭松花江特大桥挠度测量分析

分析了陶赖昭松花江特大桥挠度测量结果。利用QY倾角仪对该桥第六跨和第十跨进行了9组静挠度和36组动挠度的实测，并同光电桥梁挠度检测仪的测量结果进行了比较。对比结果表明利用倾角仪测量桥梁挠度的结果是可靠的，精度是有保证的。     

聊古-井逸出气氦数字化观测资料分析及其映震能力的初步研究

简要介绍了一种新型测氦仪-GWK-201型测氦仪，分析了聊古一井1998年9月1日～1999年11月30日的逸出气氦观测资料。结果表明：该资料的正常动态为近直线型，并且在附近4.0级地震前有显的异常显示，对今后的地震预报探索研究具有一定的参考价值。     

大地电磁感应的场源效应

本文对大地电磁感应的场源效应进行了较详细的研究.用线电流为场源,均匀大地和三层结构为构造模型进行了计算,其结果与均匀场源的感应作了对比.场源效应受场源高度、信号周期、电阻率、测点距离等的影响.为了能更深入的了解和控制这影响,本文提出了“阻抗平均法”,该方法对消减场源效应有一定作用,使平面波的解释继续有效.     

矿震识别及成因研究进展

矿震主要受开采活动、矿山所处构造环境及区域构造应力场的影响。本文首先回顾了矿震的识别研究进展,然后从矿震震源机制、矿震与构造关系、矿震与瓦斯溢出、矿震与开采进程关系、矿震成因力学机制理论与实验研究等角度对矿震的成因研究进行了阐述,最后给出矿震识别及成因研究的进一步建议。矿震成因研究深化了对天然地震的认识。在研究矿震发生机理时,必须针对具体条件进行深入讨论与分析,应更多采用有关数学和力学手段,结合具体的生产地质条件和科学实验研究,有针对性地开展研究工作。可利用层析成像技术详细了解矿震演变过程,深化对地壳介质在应力作用下发生破裂或位错过程的认识,进而对矿震发震成因进行深入研究。     

南澎列岛及其附近海域、岛屿的地震地质特征

南澎列岛及其附近海域、岛屿地震构造上属东南沿海泉州——汕头地震构造带东支的南段,近年来地震,地质和海洋部门很多学者和研究者对该地震构造带做了很多调查研究工作,使对该地震构造带的认识愈来愈深入。但上述研究大部分主要限于沿岸第四纪盆地及其附近地带,对海域内及岛屿上的地震地质特点论述不多,因此详细地研究该带在海域内和岛屿上的地震地质特点,对于深入了解东南沿海的地震构造,震源物理和地震活动,对于沿海国民经济建设都有重要意义。     

第八届国际盐湖会议将于2002年7月在俄罗斯召开

第八届国际盐湖会议将于 2 0 0 2年 7月 2 6日在俄罗斯哈卡斯 (Ｋｈａｋａｓｓｉａ)共和国召开 .国际盐湖学会是国际盐湖领域研究的权威学术组织 .学会的宗旨和目的是帮助内陆盐湖 (包括盐田 )领域的研究人员建立密切联系 ,使公众更多地了解盐湖领域的科学研究、管理和保护 .学会拥有自己的专门网站、期刊和完善的会员登记制度 ,每三年举行一次国际会议 .2 0 0 1年 1月 2 2日新修订的章程对学会的各个方面进行了详细规定 .本次会议的主题是 :生物技术和医学研究在盐湖管理中的应用 .涉及的内容有 :人口动力学、热带相互作用、微生物加工、当…     

GOCE卫星监测的中国区域重力异常

介绍了利用最新一代重力卫星GOCE(Gravity field and steady-state Ocean Circulation Explorer)重力场模型数据计算重力异常的原理和方法,采用最新发布的GOCE重力场模型数据(2009年10月-2010年7月)计算了中国区域(70°～130°E,15°～55°N)的重力异常,为了进一步分析重力异常与区域地质构造及地震活动性的对应关系,将计算结果与中国区域地形、地震活动区域等资料进行了对比分析,结果表明利用GOCE重力场模型数据计算的重力异常能够较好的反映区域地质构造分布特征,而且强震震中通常位于重力异常变化剧烈的高梯度带上.     

融合GOCE和GRACE卫星数据的无约束重力场模型Tongji-GOGR2019S

本文在法方程层面融合GOCE卫星的V_xx、V_yy、V_zz和V_xz重力梯度分量观测数据和GRACE卫星观测数据,采用直接法解算了220阶次的重力场模型Tongji-GOGR2019S.首先利用ⅡR带通滤波器在5~41 mHz的重力梯度带宽范围内对约24个月的GOCE重力梯度观测方程进行无相移滤波处理,并组成解算220阶次重力场模型的法方程,各梯度分量根据相对于参考模型统计精度进行定权;然后与13.5 a GRACE数据建立的180阶次Tongji-Grace02s重力场模型的法方程进行叠加,解算了220阶次的无约束纯卫星重力场模型Tongji-GOGR2019S.利用EIGEN-6C4重力场模型、GNSS/水准数据、DTU15重力异常数据以及欧洲区域似大地水准面模型EGG2015等数据对Tongji-GOGR2019S模型精度进行全面的检核评定,结果表明：引入GOCE卫星梯度数据后,高于72阶的位系数精度优于Tongji-Grace02s模型,Tongji-GOGR2019S模型的整体精度接近同阶次的DIR-R6等GOCE卫星第6代模型.     

由GOCE引力场模型和CNES-CLS2010平均海面高计算的稳态海面地形

利用欧空局发布的三组GOCE引力场模型及CNES-CLS 2010平均海面高数据,计算得到了全球的稳态海面地形,进而得到了全球地转流速度图.在此基础上重点对黑潮进行了对比分析.结果表明:GOCE不同组解的稳定性较好,所计算的稳态海面地形的差异基本在厘米量级内,这间接表明了GOCE引力场模型提供的大地水准面的精度达到了厘米量级.此外,通过将GOCE与GRACE相应结果进行对比发现,GOCE可提供更多的局部信息,特别是对于流速快、水流窄的边界流,如黑潮、墨西哥湾流等,GOCE所得结果更加清晰,速度也更精确.     

GOCE Data Processing: The Spherical Cap Regularization Approach

Due to the sun-synchronous orbit of the satellite gravity gradiometry mission GOCE, the measurements will not be globally available. As a consequence, using a set of base functions with global support such as spherical harmonics, the matrix of normal equations tends to be ill-conditioned, leading to weakly determined low-order spherical harmonic coefficients. The corresponding geopotential strongly oscillates at the poles. Considering the special configuration of the GOCE mission, in order to stabilize the normal equations matrix, the Spherical Cap Regularization Approach (SCRA) has been developed. In this approach the geopotential function at the poles is predescribed by an analytical continuous function, which is defined solely in the spatially restricted polar regions. This function could either be based on an existing gravity field model or, alternatively, a low-degree gravity field solution which is adjusted from GOCE observations. Consequently the inversion process is stabilized. The feasibility of the SCRA is evaluated based on a numerical closed-loop simulation, using a realistic GOCE mission scenario. Compared with standard methods such as Kaula and Tikhonov regularization, the SCRA shows a considerably improved performance.     

单加速度计模式下的GOCE卫星重力场建模方法研究

GOCE卫星由于加速度计的特殊安装方式,其非保守力主要由普通模式的组合加速度提供,使得单个加速度计的特征更难提取.本文首次采用实测数据,研究了单加速度计模式下的高低跟踪数据处理.利用GOCE任务2009年(2009-11—2009-12)的实测数据,分别以GOCE卫星梯度仪坐标系三个坐标轴正向的加速度计为研究对象,利用1s间隔的高采样轨道数据,采用动力法同时进行卫星重力场建模和加速度计的精密校准.为了克服两极地区的数据缺失对重力场模型低次系数的影响,即所谓的极空白问题,引入同期GRACE卫星的观测数据,采用方差分量估计方法,建立了GRACE/GOCE卫星跟踪卫星重力场模型WHU-GRGO-SST.该模型完全到100阶次,经6169个美国GPS水准点数据检验,在同阶次上与EGM2008和GGM05S的精度水平相同.分析发现,GOCE卫星的加速度计偏差参数存在显著的漂移,也显示了单加速度计模式处理GOCE高低跟踪数据的优势.本文的研究成果为建立静态高分辨率、高精度的GRACE/GOCE重力场模型提供了更严密的模型与技术方案,同时也为GOCE卫星梯度仪校准,以及梯度数据的深入分析提供了重要的参考信息.     

卫星重力学与重力卫星研究进展

综述了地球重力场研究对揭示其运动和时变与地震之间的关系的重要性；介绍了当今国际固体地球科学与防灾研究的一个新热点——卫星重力学与重力卫星研究的进展。随着重力卫星计划的实施，地球重力场的研究也将因此产生质的变化。文章对CHAMP、GRACE和GOCE重力卫星作了介绍。     

顾及多方向观测值权比反演地球重力场的动力积分法

考虑到不同坐标系下各个方向观测值对反演地球重力场的频谱贡献不同,建立了顾及多方向观测值权比的动力积分法,并利用该方法反演了高精度的GOCE HL-SST卫星重力场模型.首先,分析了不同坐标系下各个方向观测值与地球重力场信息的响应关系,其中惯性系(IRF)下X、Z方向的观测值分别对扇谐系数、带谐系数最为敏感,Z方向的解算精度在全频段均略高于X、Y方向;地固系(EFRF)下各个方向的独立解算精度均与能量守恒法的解算精度相当;局部指北坐标系(LNOF)下X、Z和Y三个方向的解算精度依次递减,且Y方向在47阶附近有明显"驼峰"现象.其次,比较了不同坐标系下顾及三个方向观测值权比的加权解算模型,其中加权联合解算模型精度在20至70阶次均明显优于等权解算模型,在带谐项和共振阶次精度提升明显,且LNOF下的加权联合解算精度要优于IRF和EFRF.最后,比较了GOCE和CHAMP卫星的模型解算精度,采用本文计算方法,仅利用2个月GOCE轨道观测值解算的模型精度优于包含更长观测时段信息的AIUB-CHAMP01S和EIGEN-CHAMP03S模型,且略优于ASU-GOCE-2months模型.     

GOCE Gravity Field Processing Strategy

A processing strategy and the corresponding software architecture for the processing of GOCE (Gravity field and steady-state Ocean Circulation Explorer) observables is presented and described, with the major objective to compute a high-accuracy, high-resolution spherical harmonic model of the Earth's gravity field. The combination of two numerical solution strategies, i.e. the rigorous solution of the corresponding large normal equation systems applying parallel processing (on a PC cluster) as the core solver, and the fast semianalytic approach as a quick-look gravity field analysis (QL-GFA) tool, is proposed. Such a method fusion benefits from the advantages of the individual components: the rigorous inversion of the system providing also the full variance-covariance information, and the quickness enabling the consecutive production of intermediate gravity field solutions, for the purpose to analyse partial and incomplete data sets and to derive a diagnosis of the performance of the GOCE measurement system. The functionality and operability of the individual components are demonstrated in the framework of a closed loop simulation, which is based on a realistic mission scenario both in terms of the orbit configuration and the coloured measuring noise. Special concern is given to the accuracy of the recovered coefficients, the numerical behaviour, the required computing time, and the particular role of the individual modules within the processing chain. In the case of the core solver, it is demonstrated that the assembling and rigorous solution of large normal equation systems can be handled by using Beowulf clusters within a reasonable computing time. The application of the quick-look tool to partial data sets with short-term data gaps is demonstrated on the basis of several case studies. Additionally, the spectral analysis of the residuals of the adjustment is presented as a valuable tool for the verification of the noise characteristics of the GOCE gradiometer.     

High-harmonic geoid signatures related to glacial isostatic adjustment and their detectability by GOCE

The Earth’s asthenosphere and lower continental crust can regionally have viscosities that are one to several orders of magnitude smaller than typical mantle viscosities. As a consequence, such shallow low-viscosity layers could induce high-harmonic (spherical harmonics 50–200) gravity and geoid anomalies due to remaining isostasy deviations following Late-Pleistocene glacial isostatic adjustment (GIA). Such high-harmonic geoid and gravity signatures would depend also on the detailed ice and meltwater loading distribution and history.ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite mission, planned for launch in Summer 2008, is designed to map the quasi-static geoid with centimeter accuracy and gravity anomalies with milligal accuracy at a resolution of 100 km or better. This might offer the possibility of detecting gravity and geoid effects of low-viscosity shallow earth layers and differences of the effects of various Pleistocene ice decay scenarios. For example, our predictions show that for a typical low-viscosity crustal zone GOCE should be able to discern differences between ice-load histories down to length scales of about 150 km.One of the major challenges in interpreting such high-harmonic, regional-scale, geoid signatures in GOCE solutions will be to discriminate GIA-signatures from various other solid-earth contributions. It might be of help here that the high-harmonic geoid and gravity signatures form quite characteristic 2D patterns, depending on both ice load and low-viscosity zone model parameters.     

A Wavelet-Based Assessment of Topographic-Isostatic Reductions for GOCE Gravity Gradients

Gravity gradient measurements from ESA’s satellite mission Gravity field and steady-state Ocean Circulation Explorer (GOCE) contain significant high- and mid-frequency signal components, which are primarily caused by the attraction of the Earth’s topographic and isostatic masses. In order to mitigate the resulting numerical instability of a harmonic downward continuation, the observed gradients can be smoothed with respect to topographic-isostatic effects using a remove–compute–restore technique. For this reason, topographic-isostatic reductions are calculated by forward modeling that employs the advanced Rock–Water–Ice methodology. The basis of this approach is a three-layer decomposition of the topography with variable density values and a modified Airy–Heiskanen isostatic concept incorporating a depth model of the Mohorovi?i? discontinuity. Moreover, tesseroid bodies are utilized for mass discretization and arranged on an ellipsoidal reference surface. To evaluate the degree of smoothing via topographic-isostatic reduction of GOCE gravity gradients, a wavelet-based assessment is presented in this paper and compared with statistical inferences in the space domain. Using the Morlet wavelet, continuous wavelet transforms are applied to measured GOCE gravity gradients before and after reducing topographic-isostatic signals. By analyzing a representative data set in the Himalayan region, an employment of the reductions leads to significantly smoothed gradients. In addition, smoothing effects that are invisible in the space domain can be detected in wavelet scalograms, making a wavelet-based spectral analysis a powerful tool.