INVERSION OF POST-STACK SEISMIC DATA USING SIMULATED ANNEALING1

Model-based inversion of seismic reflection data is a global optimization problem when prior information is sparse. We investigate the use of an efficient, global, stochastic optimization method, that of simulated annealing, for determining the two-way traveltimes and the reflection coefficients. We exploit the advantage of an ensemble approach to the inversion of full-scale target zones on 2D seismic sections. In our ensemble approach, several copies of the model-algorithm system are run in parallel. In this way, estimation of true ensemble statistics for the process is made possible, and improved annealing schedules can be produced. It is shown that the method can produce reliable results efficiently in the 2D case, even when prior information is sparse.     

唐山7．8级地震前地震前兆综合加权信息量的变化

地震前兆综合加权信息量是在地震综合信息量的基础上,改进了地震前兆异常出现概率的计算方法后,得出的一种综合预报新方法。利用“地震预报专家系统”的思想对每一异常事件进行综合评估。考虑到异常的可靠性、有效性、显著性及相互关联性给予不同的权重,以每一异常事件的最可能发震时间来估算异常出现的概率,计算了华北地区1970年以来地震前兆综合加权信息量,分析了1978年7月28日唐山7．8级地震前这种信息量变化的特点。     

大地电磁与地震资料仿真退火约束联合反演

在对仿真退火算法研究的基础上,将非常快速仿真退火的连续模型空间改为可变的离散化形式,理论模型试算表明,使用本文方法可提高工作效率5-10倍. 为适应联合反演的需要, 对非常快速仿真退火的误差"单判断"检验准则改为误差"双判断"检验准则,避免Metrop olis接受准则的判断失误. 在此基础上,实现了一维及二维起伏地形条件下大地电磁与地震资料多参量信息的联合反演. 理论模型的试算及实例说明了约束联合反演的有效性.     

大地电磁与地震资料仿真退火约束联合反演

在对仿真退火算法研究的基础上,将非常快速仿真退火的连续模型空间改为可变的离散化形式,理论模型试算表明,使用本文方法可提高工作效率5-10倍. 为适应联合反演的需要, 对非常快速仿真退火的误差"单判断"检验准则改为误差"双判断"检验准则,避免Metrop olis接受准则的判断失误. 在此基础上,实现了一维及二维起伏地形条件下大地电磁与地震资料多参量信息的联合反演. 理论模型的试算及实例说明了约束联合反演的有效性.     

A NEW APPROACH TO THE INVERSION OF SEISMIC DATA*

A new inversion method for seismic reflection data is based on impedance concepts and uses transformations to reduce the essentially non-linear problem to a linear eigenvalue formulation without approximation. A set of reflection data has been inverted using this method. The characteristic impedances of the layers so determined are compared with log data from a reference borehole.     

ITERATIVE TOMOGRAPHIC METHODS TO LOCATE SEISMIC LOW-VELOCITY ANOMALIES: A MODEL STUDY1

The possibilities for reconstructing seismic velocity distributions containing low-velocity anomalies by iterative tomographic methods are examined studying numerical and analogue 2D model data. The geometrical conditions of the model series were designed to generalize the geometrical characteristics of a typical cross-hole tomographic field case. Models with high (30%) and low (8%) velocity contrasts were realized. Traveltimes of 2D ultrasonic P-waves, determined for a dense net of raypaths across each model, form the analogue data set. The numerical data consists of traveltimes calculated along straight raypaths. Additionally, a set of curved-ray traveltimes was calculated for a smoothed version of the high-contrast model. The Simultaneous Iterative Reconstruction Technique (SIRT) was chosen from the various tomographic inversion methods. The abilities of this standard procedure are studied using the low-contrast model data. The investigations concentrate on the resolving power concerning geometry and velocity, and on the effects caused by erroneous data due to noise or a finite time precision. The grid spacing and the source and receiver patterns are modified. Smoothing and slowness constraints were tested. The inversion of high-contrast analogue model data shows that curved raypaths have to be considered. Hence, a ray-tracing algorithm using velocity gradients was developed, based on the grid structure of the tomographic inversion. This algorithm is included in the SIRT-process and the improvements concerning anomaly localization, resolution and velocity reconstruction are demonstrated. Since curved-ray tomography is time-consuming compared with straight-ray SIRT, it is necessary to consider the effects of grid spacing, ray density, slowness constraints and the     

A SIMPLE APPROACH TO HIGH RESOLUTION SEISMIC PROFILING FOR COAL*

Seismic exploration techniques which have been developed for oil prospecting contribute a valuable means for surveying coal measures. Since the object is to detect minor faults within the first 1500 m, rather than structural features at great depth, the new technique requires much higher resolution in the early part of the traditional seismic cross-section. Higher resolution means broader bandwidth, which must be obtained by extending the high frequency end of the spectrum. This is achieved (a) by scaling down the explosive charge size and using single geophones instead of groups, and (b) by reducing the sampling interval in space and time. Noise which does not scale down includes static anomalies and ground-roll. The consideration of statics, ground-roll, and the high-cut filtering effect of the near surface layers forces the use of deep shot holes and, where possible, deep detectors. This approach is confirmed by experiments and has been implemented on a regular basis in production. It is demonstrated that the present technique will clearly resolve faults with a vertical throw of about 5 m at 800 m depth.     

地震数据模型优化过程方法及初步应用

由于地震数据种类繁多且数量不断增大,使得地震数据共享和数据服务面临的困难越来越大.针对这个问题,提出了基于PowerDesigner建模工具对已有的地震数据模型进行优化的过程方法.并将此方法初步应用于现有的1/400万活动断层GIS数据库中,针对该库目前存在的问题,实现了对断层数据模型的优化,结合具体的实例,应用了优化...     

地震科技档案信息资源的开发利用

叙述了地震科技档案开发利用的意义,对如何做好地震科技档案开发利用工作进行了探讨。     

RESIDUAL STATICS ESTIMATION: SCALING TEMPERATURE SCHEDULES USING SIMULATED ANNEALING1

Linearized residual statics estimation will often fail when large static corrections are needed. Cycle skipping may easily occur and the consequence may be that the solution is trapped in a local maximum of the stack-power function. In order to find the global solution, Monte Carlo optimization in terms of simulated annealing has been applied in the stack-power maximization technique. However, a major problem when using simulated annealing is to determine a critical parameter known as the temperature. An efficient solution to this difficulty was provided by Nulton and Salamon (1988) and Andresen et al. (1988), who used statistical information about the problem, acquired during the optimization itself, to compute near optimal annealing schedules. Although theoretically solved, the problem of finding the Nulton–Salamon temperature schedule often referred to as the schedule at constant thermodynamic speed, may itself be computationally heavy. Many extra iterations are needed to establish the schedule. For an important geophysical inverse problem, the residual statics problem of reflection seismology, we suggest a strategy to avoid the many extra iterations. Based on an analysis of a few residual statics problems we compute approximations to Nulton–Salamon schedules for almost arbitrary residual statics problems. The performance of the approximated schedules is evaluated on synthetic and real data.     

老旧房屋震害预测的一个数学模型

本从云南城市建筑的实际出发，给出一个老旧房屋震害预测的数学模型。     

强震前地震活动图象与震源机制类型的相关性分析

在对1966年以来63次强震前中等地震活动图象全时空扫描的基础上,讨论了大陆不同构造区域、不同震源机制强震前中等地震活动图象异常演化特征及其主要活动图象与震源机制节面的相关性. 研究表明:强震前中等地震活动图象显现出应力集中和减弱两个阶段性特征,第一阶段（中期阶段）的活动图象以条带、空区和集中活跃为主;第二阶段（中短期）以持续平静为主. 走滑和正断层机制震前显示出较好的特征图象;逆冲断层震前的活动图象与其它两种机制的图象不同,没有明显的特征图象,两个阶段都有平静现象出现. 强震前中等地震条带走向与震源机制的两个节面走向一致性较好,但空区的一致性较差.      

A STATISTICAL APPROACH TO THE EXTRACTION OF THE SEISMIC PROPAGATING WAVELET*

A model of the seismic trace is generally given as a convolution between the propagating wavelet and the reflectivity series of the earth and normally it is assumed that a white noise is added to the trace. The knowledge of the propagating wavelet is the basic point to estimate the reflectivity series from the seismic trace. In this paper a statistical method of wavelet extraction from several seismic traces, assuming the wavelet to be unique, is discussed. This method allows one to obtain the propagating wavelet without any classical limitative assumptions on the phase spectrum. Furthermore, a phase unwrapping method is suggested and some statistical properties of the phase spectrum of the reflectivity traces are examined.     

A PARAMETRIC APPROACH TO THE COMPRESSION OF SEISMIC SIGNALS BY FREQUENCY TRANSFORMATION*

The compression of seismic signals which have propagated through a dispersive medium can be achieved by a frequency-domain transformation. This transformation is formally related to the dispersion characteristic of the medium and is independent of phase and group velocities. By defining a suitable cost-function to measure the degree of dispersion of a time- signal, an iterative technique can be employed to find that transformation which gives minimum dispersion. In this paper, we assume that the inverse of the dispersion characteristic can be adequately approximated by a finite polynomial in the region of maximum signal energy density. The coefficients of this polynomial are the parameters of dispersion of the medium. These parameters can be estimated both in the presence of noise and in the case of signals made up of multiple arrivals. The techniques developed in this paper are applied to seismic signals which have been recorded underground by a set of geophones designed to detect and map discontinuities in coal-seams. Results of dispersion estimation and signal compression are discussed for data collected in the Blackshale seam, Pye Hill Colliery, near Derby, in the United Kingdom.     

改进的钢筋混凝土结构双参数地震破坏模型

本文在分析现有结构地震破坏模型的基础下，提出了一种改进掇参数地震破坏模型。文中采用三线退化型恢复力模型对实际钢筋混凝土结构在实际地震作用下的变形与累积耗能，极限变形与极限滞回耗能进行了分析，通过模型计算的破损结果与实际在结果的对比，研究了模型参数，从而建立了钢筋混凝土结构的双参数地震破坏模型。     

地震烈度衰减关系统计方法的探讨

在地震学和地震工程学的研究中，地震烈度衰减关系的研究和应用日益受到重视。本文从在等烈度外包线上如何取烈度值，烈度衰减曲线的头尾处理，Ｒ０值的选取，衰减公式的偏差这四个方面对目前广泛使用的地震烈度衰减关系的统计方法作了分析和探讨，指出了这些方法中存在的不足，并提出了改进的建议。     

震源体破裂行为的重整化群方法研究

应用重整化群方法对一维、二维和三维震源体的破裂问题进行了研究，得到了一维、二维和三辰原体破裂的临界概率值分别国０．２０６３、０．１７０７和０．１５９９，相关长度指数分别为１．４３８８、０．８０８４和０．５７５７。进而由此揭示了临界概率和相关长度指数随维数增大而减少的变化规律。     

层析成像新算法及其在工程检测上的应用

基于走时和振幅的层析成像反演涉及大型稀疏矩阵方程的求解，当矩阵严重病态时，目前流行的正交分解型迭代算法难以取得良好的成像效果．本文介绍一种改进的ＬＳ_ｑＲ算法，即带阻尼的ＬＳ_ｑＲ迭代算法，它应用在北京机场高速公路桥墩施工质量检测中，取得了良好的效果．     

层析成像新算法及其在工程检测上的应用

基于走时和振幅的层析成像反演涉及大型稀疏矩阵方程的求解,当矩阵严重病态时,目前流行的正交分解型迭代算法难以取得良好的成像效果．本文介绍一种改进的ＬＳｑＲ算法,即带阻尼的ＬＳｑＲ迭代算法,它应用在北京机场高速公路桥墩施工质量检测中,取得了良好的效果．     

新疆地震趋势的模糊灰色预测

从模糊数学和灰色系统理论两个不同角度来分析地震事件，把模糊数学的表达方式用于灰色灾变预测ＧＭ（１，１）中，建立了地震预测的模糊灰色模型。用此模型讨论了南北天山四个区（带）的震级序列，在等维情况下，对比了模糊灰色方法与单纯灰色方法的优劣，讨论了影响预测结果的因素，最后给出了不同目标震级下各区（带）的预测值。