干涉走时微地震震源定位方法

本文基于地震波场干涉原理,建立了干涉走时微地震震源定位方法.该方法将两个接收点相对于一个微地震事件的走时差(称为干涉走时)的扰动作为残差函数,通过迭代求解最小残差函数,最终获得震源的空间位置.干涉走时震源定位方法利用两个接收点的到时差消除发震时刻未知和速度模型误差的影响,简化了震源定位算法.数值计算表明,本文提出的干涉走时定位方法在速度模型有误差的情况下仍然可以获得准确的微地震震源定位.     

大同地震台远震波形走时残差的计算和应用

选取大同地震台记录的2010—2019年531个M_S≥5.0地震事件,根据发震区域的不同对其波形走时残差进行分析,得到不同发震区域地震波形的平均走时残差。结果表明,日本、喜马拉雅地区地震波形的走时残差总体为负值,平均残差分别为-1.51 s、-0.70 s;斐济、中国台湾地区、南美洲西海岸地区大多为正值,平均残差为0.79 s、1.83 s、1.86 s。同时发现,在有干扰的情况下参考不同区域平均走时残差计算结果,通过判断实际初至震相与理论初至震相的位置关系,可以更好地开展初至波震相识别工作。     

利用J-B地震走时表和IASPEI走时表计算P波残差分析黑龙江省国家测震台的区域地震误差成因

利用黑龙江省国家测震台接收到的日本本岛及周边海域、台湾岛东北部及附近海域、中国大陆东北深震区以及中国东北与俄罗斯交界处部分地震,使用J-B地震走时表和IASPEI走时表分别计算P波走时残差,探讨黑龙江省测震台站接收研究区域地震事件误差成因。     

基于克里金方法的区域震相走时标定技术研究

在台网比较稀疏的情况下,台站走时标定是提高低震级事件定位、识别能力的重要手段.为了提高稀疏台网的定位精度,首先利用标定事件和IASPEI1991走时表以及中国大陆走时表,计算了初至P波和Lg波到AAK,MAKZ,NIL,TLG以及WMQ等5个台站的走时残差;接着,采用非平稳贝叶斯克里金方法和走时残差数据构造上述台站的走时校正曲面;最后,通过加入和不加入走时校正定位一系列位置准确的发生在新疆地区的地震事件评估克里金走时校正的有效性.结果表明,克里金走时校正能够较大地提高稀疏台网的定位精度,同时有效地缩小误差椭圆的面积.     

基于克里金方法的区域震相走时标定技术研究div.

在台网比较稀疏的情况下,台站走时标定是提高低震级事件定位、识别能力的重要手段．为了提高稀疏台网的定位精度,首先利用标定事件和IASPEI1991走时表以及中国大陆走时表,计算了初至P波和Lg波到AAK,MAKZ,NIL,TLG以及WMQ等5个台站的走时残差;接着,采用非平稳贝叶斯克里金方法和走时残差数据构造上述台站的走时校正曲面;最后,通过加入和不加入走时校正定位一系列位置准确的发生在新疆地区的地震事件评估克里金走时校正的有效性．结果表明,克里金走时校正能够较大地提高稀疏台网的定位精度,同时有效地缩小误差椭圆的面积．      

基于局部一维模型与走时标定的区域三维速度模型构建技术研究

构建区域介质三维速度模型并以之获得准确的区域震相走时,是提高区域地震定位精度的重要手段之一.为充分利用已有的一维模型、GT事件、地质资料等实现三维模型构建,尝试基于目标区域内已有的部分局部一维模型,通过克里金空间插值建立初始三维模型,然后利用GT事件走时数据并参考其它地震地质资料对其不断进行修正,使得其走时偏差图与GT事件走时偏差图一致,进而获得能够提高区域地震定位精度的三维模型.使用不同模型进行的地震定位实验表明,以此方法建立的三维模型的定位偏差较初始模型减少约20％,较好地起到了减小区域震相走时残差,提高区域地震定位精度的作用.     

区域地震走时表的检验

走时表不仅是鉴定地震图上的震相、确定震源参数的重要工具,而且其走时提供了有关地球内部最重要的资料。所以,走时表是地震和地球物理研究中心不可少的工具。由于科学研究的深入发展,人们对资料的要求越来越高,大范围的走时表(如 J—B 表)已不能适应研究工作的深入发展,尽快做出精确度更高的区域走时表便成为广大地震工作者十分迫切的愿望。     

基于局部一维模型与走时标定的区域 三维速度模型构建技术研究

构建区域介质三维速度模型并以之获得准确的区域震相走时, 是提高区域地震定位精度的重要手段之一. 为充分利用已有的一维模型、 GT事件、 地质资料等实现三维模型构建, 尝试基于目标区域内已有的部分局部一维模型, 通过克里金空间插值建立初始三维模型, 然后利用GT事件走时数据并参考其它地震地质资料对其不断进行修正, 使得其走时偏差图与GT事件走时偏差图一致, 进而获得能够提高区域地震定位精度的三维模型. 使用不同模型进行的地震定位实验表明, 以此方法建立的三维模型的定位偏差较初始模型减少约20%, 较好地起到了减小区域震相走时残差, 提高区域地震定位精度的作用.      

昆明台P波走时残差与东川、通海、昭通地震

本文分析了昆明台1962年至1974年P波走时残差随时间变化的情况,发现1966年2月5日东川地震和1974年5月11日昭通地震前,残差出现了较为明显的异常;1970年1月5日通海地震前残差的变化却不明显。这一结果再一次表明P波走时残差随时间的变化情况可能作为获得地震前兆信息的一种手段。     

基于图形界面的波形相关法拾取远震相对走时残差

利用图形界面操作集成两种波形相关法(多道互相关和自适应叠加)拾取远震走时残差,在该软件包中地震学研究者通过轻松点击鼠标等基本操作即可实现数据的预处理、地震波形的质量控制、走时残差结果的显示及对比分析等操作,提高远震震相走时残差的拾取效率和准确度.     

A Monte Carlo study of rainfall forecasting with a stochastic model

A procedure for short-term rainfall forecasting in real-time is developed and a study of the role of sampling on forecast ability is conducted. Ground level rainfall fields are forecasted using a stochastic space-time rainfall model in state-space form. Updating of the rainfall field in real-time is accomplished using a distributed parameter Kalman filter to optimally combine measurement information and forecast model estimates. The influence of sampling density on forecast accuracy is evaluated using a series of a simulated rainfall events generated with the same stochastic rainfall model. Sampling was conducted at five different network spatial densities. The results quantify the influence of sampling network density on real-time rainfall field forecasting. Statistical analyses of the rainfall field residuals illustrate improvement in one hour lead time forecasts at higher measurement densities.     

Earthquake Engineering and Engineering Vibration Aims And Scope

正This journal is established by the Institute of Engineering Mechanics(IEM),China Earthquake Administration,to promote scientific exchange between Chinese and foreign scientists and engineers so as to improve the theory and practice of earthquake hazards mitigation,preparedness,and recovery.To accomplish this purpose,the journal aims to attract a balanced number of papers between Chinese and     

Foreword

Destructive earthquakes have caused great damage in China and the United States and collapsing buildings havecaused many deaths and injuries. The field of earthquake engineering studies earthquake hazards, the occurrence ofearthquakes of various magnitudes, the nature of the ground shaking during an earthquake, the vibration of structuresduring earthquakes, the strengthening of existing structures and the design of new structures to be earthquake resistant,and finally, how to cope with earthquake damage and restore a city to normal functioning. Such efforts are in progressin both countries, but unfortunately, the language barrier interferes with the free flow of information between China andthe Untied States. It would be mutually beneficial if some means could be developed to promote the exchangeof information across the Pacific Ocean. This new journal has been established for this purpose and its success willbe an important step in promoting earthquake engineering in China and the United States.     

WORLD ASSOCIATION FOR SEDIMENTATION AND EROSION RESEARCH(WASER)

正President:Giampaolo Di Silvio,Italy Vice Presidents:Ulrich C.E.Zanke,Germany Zhao-yin Wang,China The World Association for Sedimentation and Erosion Research(WASER),inaugurated on Oct.19,2004,is an independent non-governmental,non-profit organization.The mission of WASER is to promote international co-operation on the study     

Enhancing remote sensing research on global change to improve our understanding on Earth system processes

正Global Change includes climate change and other environmental changes caused by the joint interaction among various layers of Earth. From the positive side, global change provides new opportunities to human and other living forms on Earth. In the meantime, it creates tremendous challenges and negative impact. At present, the negative impacts have reached all primary processes of the global ecosystem and every aspect of human society, especially causing degradation of the ecosystem. For instance, intensive deforestation causes decline of biodiversity; global warming causes sea level rise and increases     

Solute concentrations in the lower niger river and the source rock contribution

Water quality analyses for the Niger River for the 1980/81 hydrological year are presented. The samples were collected from the main river at Lokoja, and from two main tributaries, the Kaduna and the Benue Rivers. Different water types were distinguished by the concentrations of major ions. The type Ca > Na > Mg > K - HCO₃ > SO₄ > Cl was represented at all stations during at least part of the year. Chloride was found to dominate the sulphate ion in the Kaduna and Niger, while the Benue maintained a higher concentration of sulphate relative to chloride all year round. Distinct patterns of seasonal variation in the ion concentrations were observed, particularly for the samples collected at Lokoja. Low ion concentrations were prominent during periods of high discharge, while low flow periods coincided with high dissolved ion concentrations. The contribution of rainwater to the total dissolved solids in the river waters was assessed indirectly using rainwater chemistry data from the Gulf of Guinea. The estimated rainwater contribution to the Lower Niger amounts to 5.15 mg 1^?1. Geochemical weathering calculations involving reactions of the four major minerals of granitic rocks - anorthite, biotite, albite, and K-feldspar - with carbon dioxide and water, can account for the average water composition of the Lower Niger. The proportion of the ionic components was also related to the occurrence of the respective element in the minerals.