不同模式自组织介质中声波传播特性的比较研究

中型和大型尺度结构构造分区性, 使得地球内部介质地震波速度表征出大尺度的确定性模型, 而小尺度上微孔和裂隙的存在会导致地震波速度分布的随机扰动, 即自组织模型. 目前地震学中常用的6种模式自组织模型为: 高斯型、指数型、自相似型、白噪声、Flicker噪声和Brown 噪声. 我们从其滤波因子入手, 比较了不同模式的自组织模型特征, 结合有限差分法地震记录模拟及地震波特征分析, 对比了上述6种模式自组织介质中声波传播特性. 结果表明：地震波对不同模式的自组织介质的地震响应不同, 如波形、能量、振幅等. 由此我们可以通过分析实际地震记录的复杂性特征来鉴别其自组织类型, 从而更好地解释实际地震资料.     

正则化偏移成像的全局优化快速算法

目前,偏移后的地震剖面往往只是一个地质构造图像,还不能为后续的岩性分析和油气储层属性的提取提供更精确的信息.为了得到高分辨率真振幅的图像,建议采用正则化偏移成像方法.针对本问题数据规模大和正演算子矩阵稀疏的特点,提出采用一种新的算法--无记忆拟牛顿-模拟退火法对偏移算子方程进行求解.该方法综合了无记忆拟牛顿法优良的局部...     

The New Algorithm for Fast Probabilistic Hypocenter Locations

The spatial location of sources of seismic waves is one of the first tasks when transient waves from natural (uncontrolled) sources are analysed in many branches of physics, including seismology, oceanology, to name a few. It is well recognised that there is no single universal location algorithm which performs equally well in all situations. Source activity and its spatial variability in time, the geometry of recording network, the complexity and heterogeneity of wave velocity distribution are all factors influencing the performance of location algorithms. In this paper we propose a new location algorithm which exploits the reciprocity and time-inverse invariance property of the wave equation. Basing on these symmetries and using a modern finite-difference-type eikonal solver, we have developed a new very fast algorithm performing the full probabilistic (Bayesian) source location. We illustrate an efficiency of the algorithm performing an advanced error analysis for 1647 seismic events from the Rudna copper mine operating in southwestern Poland.     

火山地震监测在火山喷发预测中的应用

火山地震学是火山监测的一种重要方法,同时也是预测火山喷发最有效的方法。本文首先回顾了火山地震监测的历史,分析汇总了火山地震的类型和特征,并介绍了各类地震的形成机理。然后,对近年来发展起来的火山地震学方法进行了简要介绍,如地震活动性分析、实时振幅比测量、地震波速度变化和重复地震等,同时列举了具体的应用实例。最后,介绍了火山地震学方法在中国大陆火山监测中的应用。     

Perturbation methods for two special cases of the time‐lapse seismic inverse problem

Scattering theory, a form of perturbation theory, is a framework from within which time‐lapse seismic reflection methods can be derived and understood. It leads to expressions relating baseline and monitoring data and Earth properties, focusing on differences between these quantities as it does so. The baseline medium is, in the language of scattering theory, the reference medium and the monitoring medium is the perturbed medium. The general scattering relationship between monitoring data, baseline data, and time‐lapse Earth property changes is likely too complex to be tractable. However, there are special cases that can be analysed for physical insight. Two of these cases coincide with recognizable areas of applied reflection seismology: amplitude versus offset modelling/inversion, and imaging. The main result of this paper is a demonstration that time‐lapse difference amplitude versus offset modelling, and time‐lapse difference data imaging, emerge from a single theoretical framework. The time‐lapse amplitude versus offset case is considered first. We constrain the general time‐lapse scattering problem to correspond with a single immobile interface that separates a static overburden from a target medium whose properties undergo time‐lapse changes. The scattering solutions contain difference‐amplitude versus offset expressions that (although presently acoustic) resemble the expressions of Landro ( 2001 ). In addition, however, they contain non‐linear corrective terms whose importance becomes significant as the contrasts across the interface grow. The difference‐amplitude versus offset case is exemplified with two parameter acoustic (bulk modulus and density) and anacoustic (P‐wave velocity and quality factor Q) examples. The time‐lapse difference data imaging case is considered next. Instead of constraining the structure of the Earth volume as in the amplitude versus offset case, we instead make a small‐contrast assumption, namely that the time‐lapse variations are small enough that we may disregard contributions from beyond first order. An initial analysis, in which the case of a single mobile boundary is examined in 1D, justifies the use of a particular imaging algorithm applied directly to difference data shot records. This algorithm, a least‐squares, shot‐profile imaging method, is additionally capable of supporting a range of regularization techniques. Synthetic examples verify the applicability of linearized imaging methods of the difference image formation under ideal conditions.     

地动仪研究中的五个地震学基本概念

地动仪的研究涉及历史和科学的统一。古籍文字的主要部分是对测震现象的描述,研究的学术观点和模型尽可不同,但地震学基本概念和原则是需要遵循和坚持的,方能正确把握和解读史料。针对一些专业认识上的误解,本文以地震学的基本概念和学科发展史实为依据作了必要的澄清和纠正,诸如地动仪的反应方向、对地震和非地震的不同反应、陇西地震的量化分析、地震学的实验检验、在地震科学史上的作用等。还对个别的脱离实际却被媒体高调宣传的模型实验,指出了其原则性失误。地动仪研究的重点并不局限于重建一个模型,更要探寻古人如何发现和利用了自然规律,学习和掌握地震学的基本知识。     

Ambient noise as the new source for urban engineering seismology and earthquake engineering: a case study from Beijing metropolitan area

In highly populated urban centers, traditional seismic survey sources can no longer be properly applied due to restrictions in modern civilian life styles. The ambient vibration noise, including both microseisms and microtremor, though are generally weak but available anywhere and anytime, can be an ideal supplementary source for conducting seismic surveys for engineering seismology and earthquake engineering. This is fundamentally supported by advanced digital signal processing techniques for effectively extracting the useful information out from the noise. Thus, it can be essentially regarded as a passive seismic method. In this paper we first make a brief survey of the ambient vibration noise, followed by a quick summary of digital signal processing for passive seismic surveys. Then the applications of ambient noise in engineering seismology and earthquake engineering for urban settings are illustrated with examples from Beijing metropolitan area. For engineering seismology the example is the assessment of site effect in a large area via microtremor observations. For earthquake engineering the example is for structural characterization of a typical reinforced concrete high-rise building using background vibration noise. By showing these examples we argue that the ambient noise can be treated as a new source that is economical, practical, and particularly valuable to engineering seismology and earthquake engineering projects for seismic hazard mitigation in urban areas.     

Effect of coherent noise on single-station direction of arrival estimation

Polarization analysis of multi-component seismic data is used in both exploration seismology and earthquake seismology. In single-station polarization processing, it is generally assumed that any noise present in the window of analysis is incoherent, i.e., does not correlate between components. This assumption is often violated in practice because several overlapping seismic events may be present in the data. The additional arrival(s) to that of interest can be viewed as coherent noise. This paper quantifies the error because of coherent noise interference. We first give a general theoretical analysis of the problem. A simple mathematical wavelet is then used to obtain a closed-form solution to the principal direction estimated for a transient incident signal superposed with a time-shifted, unequal amplitude version of itself, arriving at an arbitrary angle to the first wavelet. The effects of relative amplitude, arrival angle, and the time delay of the two wavelets on directional estimates are investigated. Even for small differences in angle of arrival, there may be significant error (>10°) in the azimuth estimate.     

Planetary seismology

Since 1969, seismology has been extended beyond the Earth, and seismic sensors have been placed on the surface of other bodies of the solar system. A Lunar seismic network thus operated for the 8 years after 1969, with up to 4 stations, and detected some 1000 Moonquakes per year. A single seismic station was also operated on the Martian surface for 19 months since 1977. Unfortunately, it did not detect any Marsquakes, but produced useful information for future experiments. Remotesensing seismic experiments using Doppler shift observation have also been applied to Jupiter in the last two years and are beginning to return information on the normal modes. Planetary seismology is thus now well developed, and will provide increasing information on the structure and dynamics of the planets and bodies of the solar system. In this paper we review the state of the art in planetary seismology. For the terrestrial planets, we compare the seismic sources, structure and experiments on Earth, Moon and Mars. Such a comparison is useful in evaluating the design of past or future experiments. Results in the seismology of giant planets are also reviewed, stressing the connection between methods and theory.     

Note sur la crise sismo-volcanique à la soufrière de La Guadeloupe 1975–1977

Superficial volcanic manifestations occurred at Soufriere de Guadeloupe in 1976–1977. Superficial phenomena started on July 8, and had been preceded the previous year by a seismovolcanic crisis of exceptional amplitude for the Caribbean region. The essentially phreatic manifestations were accompanied by an extraordinarily high number of recorded quiakes: 16,467 earthquakes in 21 months, 153 of which classified as clearly perceived. The epicentral area covered about 30 km², and the seismic energy released reached a total of 10¹⁸ erg. Thirty-six volcanic tremors accompanied violent superficial manifestations, and 26 strong phreatic eruptions have been observed. The important role played by seismology as a crisis detector for this type of volcanoes has been clearly shown.     

Traveltime seismic tomography with adaptive wavelet parameterization

An algorithm for solving the inverse kinematic problem of traveltime seismic tomography is developed and tested. The algorithm is intended for imaging the three-dimensional (3D) velocity model composed of a layer underlain by a half-space. This algorithm considers the bottom boundary of the layer as a first-order seismic velocity discontinuity with unknown position that has to be determined in the inversion together with the velocity variations inside the overlying layer and the sub-interface boundary velocities. The inversion can be applied to the travel times of refracted, head and reflected waves. The main idea behind the algorithm is the adaptive parameterization of the medium by the sparse Haar wavelet series expansion. In order to throw off the poorly resolved coefficients of expansion, we suggest using two empirical local resolution measures: the number of seismic rays crossing the support of the corresponding wavelet support area and their angular coverage, i.e., the spread in the azimuths of these rays. The adequacy of these measures is tested by their comparison with the estimation of the diagonal elements of the resolution matrix on the synthetic examples. This comparison proved that the proposed measures can be successfully applied for statistical estimation of the resolution and for constructing the adaptive parameterization. It was shown also that the best results are achieved while using the number of rays normalized to the size of the wavelet support together with their angular coverage. An automated procedure for throwing off poorly resolved unknowns is developed. The parameters of this procedure can be tuned to provide the desired level of detail of the model to be reconstructed. The synthetic checkerboard testing proved the efficiency of the algorithm. The proposed algorithm can be applied to solve different types of problems, including regional seismic studies, as well as exploration and engineering seismology. The use of this algorithm is especially convenient when the medium is essentially three-dimensional and when the conventional seismic methods implying regular network measurements directly above the studied structure (such as the common depth point method) are inapplicable, e.g., in the seismic studies of the foundations of buildings and in rugged terrains.     

数字化台网的近震震相自动识别

首次提出了数字化台网对于近震震相自动识别的“波形变化值增长”算法和“无后续震相”判据 .前者根据波形变化值来描述近震波形的变化 ,用该值的增长捕捉地震波振幅或频率的突变 ;后者在识别到初动后考察后续波形的变化情况 ,如果没有其它震相 ,初动识别无效 .该判据使算法在初动震相振幅过小识别不清时 ,不会误将后续振幅较大的震相识别为初动震相 .该方法经实例检验表明精度符合地震速报的要求 ,并编制了相应的程序     

现代地震记录

由于我国数字地震学研究起步较晚，在很多地震学家中，对于数字地震学的意义和数字地震资料的使用还存在不少疑问。本文结合中国数字地震台网（ＣＤＳＮ）的工作，对经常提出的比较集中的两个问题，即数字地震记录的物理意义和数字地震记录与传统地震记录有哪些不同的问题进行了回答和讨论。     

Lunar noise correlation,imaging and monitoring

Passive seismic techniques have revolutionarised seismology,leading for example to increased resolution in surface wave tomography,to the possibility to monitor changes in the propagation medium,and to many new processing strategies in seismic exploration.Here we review applications of the new techniques to a very particular dataset,namely data from the Apollo 17 lunar network.The special conditions of the lunar noise environment are investigated,illustrating the interplay between the properties of the noise and the ability to reconstruct Green's functions.With a dispersion analysis of reconstructed Rayleigh waves new information about the shallow shear velocity structure of the Moon are obtained.Passive image interferometry is used to study the effect of temperature changes in the subsurface on the seismic velocities providing direct observation of a dynamic process in the lunar environment.These applications highlight the potential of passive techniques for terrestrial and planetary seismology.     

遗传算法在地球物理中的应用进展

简要介绍了遗传算法的基本原理及实现步骤；论述了遗传算法在地震数据处理中的AVO波、速度参数、静校正，波阻抗等方面的应用状况；概述了该方法在重力、电法、测井及磁力等非地震勘探的研究进展；最后讨论了遗传算法的优缺点，对遗传算法的发展及其在地球物理勘探中的进一步应用作了展望。     

Earthquake magnitude scales

The earthquake magnitude was introduced into seismology nearly 40 yr ago, as a purely empirical concept. After an unparalleled success in scientific and practical applications the magnitude is developing into a concept with a clearer physical meaning and a more solid theoretical foundation. The magnitude determined from the maximum particle amplitude or velocity reflects the maximum radiation power of the seismic source in the frequency band recorded on a particular seismograph. Recently developed models for seismic sources assist in classifying earthquakes according to size and spectral character. From corresponding scaling laws the relations between various magnitude scales can be established. The magnitude aims at enabling one to compare the sizes of seismic sources ranging in character from nearly aseismic events to explosions. While the former are characterized by a relatively long-peroidic radiation maximum, the latter radiate primarily short-periodic seismic energy. Tectonic earthquakes are likely to range in character between the two extreme spectral cases. A comparison of earthquake magnitude with stellar magnitude leads to analogies in spectral character between earthquakes and stars, whereby seismic sources seem to follow a distribution similar to the Hertzsprung-Russell diagram for stars. Before seismological practice can catch up with the new cognitions, improvements in the definition of the earthquake magnitude are in need.     

波形模板匹配定位方法在北京地区的应用

在地震学研究中，高效的微震检测方法是既重要又具有挑战性的问题。本文对波形模板匹配检测方法、匹配定位技术、波形自相关检测技术进行详细介绍和对比，对国内外应用实例进行总结，并展望微震检测方法应用前景和发展趋势。利用基于图形处理器加速的匹配定位技术和双差地震定位法，对北京地区19个台站记录的2015年连续地震资料进行分析。基于中国地震台网中心提供的地震目录，筛选出245个地震事件作为模板事件，检测得到1229个地震事件，约为地震台网原始地震目录数量的5倍。精定位结果可显示小震沿黄庄-高丽营断裂周边小断裂分布形态特征，本文微震检测和定位结果可为研究北京地区地震活动性与发震断层深部构造提供基础数据支撑。     

机器学习在地震检测与震相识别的应用综述

在地震学研究中地震检测与震相识别是最基础的环节,其拾取速度和精度直接影响其在地震精确定位以及地震层析成像中的应用效率和精度。近年来,机器学习在地震学领域中引起广泛关注。机器学习可以改进传统地震检测和震相识别方法,使它们能达到更加准确,识别率更高的效果。把机器学习方法按照监督学习和无监督学习分类介绍,并对机器学习方法流程进行总结,并对目前在地震检测与震相识别方面应用较为广泛的机器学习方法(卷积神经网络、指纹和相似性阈值、广义相位检测、PhaseNet、模糊聚类)进行综述。结果表明:机器学习在地震事件检测和震相识别将会是主要的手段。数据驱动的机器学习在地震学中的应用和物理模型的联合运用将是未来的发展趋势。     

The Present Status and Prospect of Earthquake Focal Depth Locating

Locating an earthquakes focal depth is always a key project in seismology. Precise focal depth is of critical importance for evaluating seismic hazards, deciphering dynamic mechanisms of earthquake generating,estimating aftershock evolutions and risk,as well as monitoring nuclear tests. However,how we determine an accurate focal depth is always a challenge in seismological studies. Aiming to solve these problems, we analyzed and summarized the present status and the future development of earthquake focal depth locating. In this paper we first reviewed the present status of focal depth locating in the world,and summarized the frequently-used relocating methods and ideas at present,and introduced two types of focal depth relocating ideas: arrival time relocating and waveform modeling methods. For these ideas,we systematically described the S-P and the Pn-Pg methods that belong to arrival time method,and polarization focal depth locating and amplitude focal depth locating that belongs to waveform modeling,and further analyzed the advantages and limitations of these methods. Since the depth phase methods are highly sensitive to focal depth,and are relatively free from the uncertainties of crustal models,we mainly reviewed the depth phases of s Pm P,s PL,s Pn,and s Sn,and quantitatively evaluated their availabilities and characteristics. Second,we also discussed the effects of crustal velocity models on the reliability of focal depth locating,and reviewed the advancements of seismic tomography techniques over recent years. Finally,based on the present status of the progress on the focal depth locating,and studies of seismic velocity structures,we proposed an idea of combining multiple datasets and relocating methods,jointly utilizing seismologic and geodetic techniques to relocate focal depth,which should be the major research field in investigating focal depth and source parameters in the near future.     

移动线源的Green函数求解及辐射能量分析:高铁地震信号简化建模

在基于人工主动源的勘探地震学中,往往采用固定位置和激发时间的点源数学模型来描述爆炸型震源或可控震源,因此就有了描述单点力源作用下的弹性全空间或半空间中弹性波传播的Green函数,成为了勘探地震学的重要理论基础.而如今,行进中的高速列车(高铁)是一种全新的主动源,其接近匀速的运行速度、确定的长度和荷载使其可以被重复利用.本文将行进中的高铁在数学上简化建模为一个移动线源来进行研究,给出了这一震源作用下的弹性半空间和全空间中Green函数的计算方法,并分别讨论了全空间中远场Green函数的频谱特征和空间辐射能量的方向性特点,以及半空间中Green函数与近场观测数据的对比结果,为高铁震源下的地震波传播规律和振动信号的研究与利用提供帮助.