Microearthquake analysis for hydraulic frac－turing proces

Ｍｉｃｒｏｅａｒｔｈｑｕａｋｅａｎａｌｙｓｉｓｆｏｒｈｙｄｒａｕｌｉｃｆｒａｃ┐ｔｕｒｉｎｇｐｒｏｃｅｓＹＩＮＧ－ＰＩＮＧＬＩ（李应平）ＤｅｐａｒｔｍｅｎｔｏｆＥａｒｔｈ，ＡｔｍｏｓｐｈｅｒｉｃａｎｄＰｌａｎｅｔａｒｙＳｃｉｅｎｃｅｓ，Ｍａｓａｃｈ...     

An explicit finite element－finite difference method for analyzing the effect of visco－elastic local topography on the earthquake motion

Ａｎｅｘｐｌｉｃｉｔｆｉｎｉｔｅｅｌｅｍｅｎｔ－ｆｉｎｉｔｅｄｉｆｆｅｒｅｎｃｅ　ｍｅｔｈｏｄｆｏｒａｎａｌｙｚｉｎｇｔｈｅｅｆｆｅｃｔｏｆｖｉｓｃｏ－ｅｌａｓｔｉｃ　ｌｏｃａｌ　ｔｏｐｏｇｒａｐｈｙ　ｏｎ　ｔｈｅ　ｅａｒｔｈｑｕａｋｅ　ｍｏｔｉｏｎ...     

附录K Flinn－Engahl地震区域

附录ＫＦｌｉｎｎ－Ｅｎｇａｈｌ地震区域ＣｏｄｅＳｅｉｓｍｉｃＲｅｇｉｏｎＤｅｓｃｔｐｃｉｏｎ４５３Ｃａｌｉｆｏｎｉａ－ＭｅｘｉｃｏＢｏｒｄｅｒＲｅｇｉｏｎ１１ＣｅｎｒａｌＡｌａｓｋａ４６３Ｗ．Ａｒｉｚｏｎａ－ＭｅｘｉｃｏＢｏｒｄｅｒＲｅｇｉｏｎ２１Ｓ...     

《ActaSeismologicaSinica》isinprogress──reporttothefourthsessionofacademicsymposlumofSSContheworkofASS（1992－1994）

《ＡｃｔａＳｅｉｓｍｏｌｏｇｉｃａＳｉｎｉｃａ》ｉｓｉｎｐｒｏｇｒｅｓｓ──ｒｅｐｏｒｔｔｏｔｈｅｆｏｕｒｔｈｓｅｓｓｉｏｎｏｆａｃａｄｅｍｉｃｓｙｍｐｏｓｌｕｍｏｆＳＳＣｏｎｔｈｅｗｏｒｋｏｆＡＳＳ（１９９２－１９９４）Ｘｉｎ－ＭｅｉＬＩＵａｎｄＹ...     

Study on the characteristics of crust－mantle transition zone in Western Yunnan Province

Ｓｔｕｄｙｏｎｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｃｒｕｓｔ┐ｍａｎｔｌｅｔｒａｎｓｉｔｉｏｎｚｏｎｅｉｎＷｅｓｔｅｒｎＹｕｎｎａｎＰｒｏｖｉｎｃｅＨＯＮＧ－ＸＩＡＮＧＨＵ（胡鸿翔）ＺＨＯＮＧ－ＹＡＮＧＬＩＮ（林中洋）ＹＩＮ－ＪＵＢＩＡＮ（边银...     

Expert system for earthquake prediction（ESEP）（2）－Knowledge representation and evidence combination

Ｅｘｐｅｒｔｓｙｓｔｅｍｆｏｒｅａｒｔｈｑｕａｋｅｐｒｅｄｉｃｔｉｏｎ（ＥＳＥＰ）（２）－ＫｎｏｗｌｅｄｇｅｒｅｐｒｅｓｅｎｔａｔｉｏｎａｎｄｅｖｉｄｅｎｃｅｃｏｍｂｉｎａｔｉｏｎＨｏｎｇ－ＳｈｕｎＦＡＮ（范洪顺）ａｎｄＢｉ－ＱｕａｎＷＡＮＧ（王碧泉...     

The fine velocity structure of sediment－base－ment layer in the Three－GorgesRegionoftheChangjiangRiver（YangtzeRiver）

Ｔｈｅｆｉｎｅｖｅｌｏｃｉｔｙｓｔｒｕｃｔｕｒｅｏｆｓｅｄｉｍｅｎｔ┐ｂａｓｅ┐ｍｅｎｔｌａｙｅｒｉｎｔｈｅＴｈｒｅｅ┐ＧｏｒｇｅｓＲｅｇｉｏｎｏｆｔｈｅＣｈａｎｇｊｉａｎｇＲｉｖｅｒ（ＹａｎｇｔｚｅＲｉｖｅｒ）ＨＯＮＧ－ＸＩＡＮＧＨＵ（胡鸿翔），...     

The Epi－continental arc of Southeast China and relevant earthquakes

ＴｈｅＥｐｉ┐ｃｏｎｔｉｎｅｎｔａｌａｒｃｏｆＳｏｕｔｈｅａｓｔＣｈｉｎａａｎｄｒｅｌｅｖａｎｔｅａｒｔｈｑｕａｋｅｓＪＩＡ－ＷＥＩＸＵ（徐嘉炜）ＤｅｐａｒｔｍｅｎｔｏｆＲｅｓｏｕｒｃｅａｎｄＥｎｖｉｒｏｎｍｅｎｔａｌＳｃｉｅｎｃｅｓ,ＨｅｆｅｉＵ...     

On the hydro－spectrum of deep wells and the response ability of well－aquifer system

Ｏｎｔｈｅｈｙｄｒｏ－ｓｐｅｃｔｒｕｍｏｆｄｅｅｐｗｅｌｌｓａｎｄｔｈｅｒｅｓｐｏｎｓｅａｂｉｌｉｔｙｏｆｗｅｌｌ－ａｑｕｉｆｅｒｓｙｓｔｅｍＷｅｎ－ＢｉｎＪＩＡＮ（简文彬）；Ｂａｏ－ＲｅｎＣＨＥＮ（陈葆仁）ａｎｄＳｈｕ－ＹｕｎＬＩＵ（刘淑芸）（Ｄｅ...     

Research on characteristics of magnitude structure of earthquake sequences

ＲｅｓｅａｒｃｈｏｎｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｍａｇｎｉｔｕｄｅｓｔｒｕｃｔｕｒｅｏｆｅａｒｔｈｑｕａｋｅｓｅｑｕｅｎｃｅｓＰＥＩ－ＱＩＮＧＳＵＮ（孙佩卿）ＱＩＮ－ＺＵＬＩ（李钦祖）ＹＩＮＧ－ＨＵＡＤＡＩ（戴英华）ＪＵＮＺＨＡＯ（赵军）Ｓｅ...     

Grid dispersion in generating finite-differences synthetic seismograms

Ｇｒｉｄｄｉｓｐｅｒｓｉｏｎｉｎｇｅｎｅｒａｔｉｎｇｆｉｎｉｔｅ－ｄｉｆｆｅｒｅｎｃｅｓｓｙｎｔｈｅｔｉｃｓｅｉｓｍｏｇｒａｍｓＡｂｄｏｌｒａｈｉｍＪａｖａｈｅｒｉａｎ（ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃｓ，ｔｈｅＵｎｉｖｅｒｓｉｔｙｏｆＴｅｈ...     

SEISMOGRAM SYNTHESIS AND RECOMPRESSION OF DISPERSIVE IN-SEAM SEISMIC MULTIMODE DATA USING A NORMAL-MODE SUPERPOSITION APPROACH

In spite of a geometrical rotation into radial and transverse parts, two- or three-component in-seam seismic data used for underground fault detection often suffer from the problem of overmoding ‘noise’. Special recompression filters are required to remove this multimode dispersion so that conventional reflection seismic data processing methods, e.g. CMP stacking techniques, can be applied afterwards. A normal-mode superposition approach is used to design such multimode recompression filters. Based on the determination of the Green's function in the far-field, the normal-mode superposition approach is usually used for the computation of synthetic single- and multi-mode (transmission) seismograms for vertically layered media. From the filter theory's point of view these Green's functions can be considered as dispersion filters which are convolved with a source wavelet to produce the synthetic seismograms. Thus, the design of multimode recompression filters can be reduced to a determination of the inverse of the Green's function. Two methods are introduced to derive these inverse filters. The first operates in the frequency domain and is based on the amplitude and phase spectrum of the Green's function. The second starts with the Green's function in the time domain and calculates two-sided recursive filters. To test the performance of the normal-mode superposition approach for in-seam seismic problems, it is first compared and applied to synthetic finite-difference seismograms of the Love-type which include a complete solution of the wave equation. It becomes obvious that in the case of one and two superposing normal modes, the synthetic Love seam-wave seismograms based on the normal-mode superposition approach agree exactly with the finite-difference data if the travel distance exceeds two dominant wavelengths. Similarly, the application of the one- and two-mode recompression filters to the finite-difference data results in an almost perfect reconstruction of the source wavelet already two dominant wavelengths away from the source. Subsequently, based on the dispersion analysis of an in-seam seismic transmission survey, the normal-mode superposition approach is used both to compute one- and multi-mode synthetic seismograms and to apply one- and multimode recompression filters to the field data. The comparison of the one- and two-mode synthetic seismograms with the in-seam seismic transmission data reveals that arrival times, duration and shape of the wavegroups and their relative excitation strengths could well be modelled by the normal-mode superposition approach. The one-mode recompressions of the transmission seismograms result in non-dispersive wavelets whose temporal resolution and signal-to-noise ratio could clearly be improved. The simultaneous two-mode recompressions of the underground transmission data show that, probably due to band-limitation, the dispersion characteristics of the single modes could not be evaluated sufficiently accurately from the field data in the high-frequency range. Additional techniques which overcome the problem of band-limitation by modelling all of the enclosed single-mode dispersion characteristics up to the Nyquist frequency will be mandatory for future multimode applications.     

频率域中的合成地震记录

波动理论的合成地震记录是地震资料处理和解释中的重要研究课题。 目前,制作波动理论的合成记录主要是用Trorey的克希霍夫方法,正在研究的有有限差分法和有限元素法。本文提出一种新的方法,在频率域中制作波动理论的合成记录,给出了与克希霍夫绕射波方程等价的频率域中的绕射波方程。在国产DJS-11型计算机上,应用两种绕射波方程实现了合成地震记录,并且进行了比较,认为频率域方法是有效的,可以用于波动方程偏移和地震资料解释,进一步工作有可能获得多层变速模型的波动理论记录。     

Determining the focal mechanisms and depths of relatively small earthquakes using a few stations by full‐waveform modelling

Determining the focal mechanism of earthquakes helps us to better define faults and understand the stress regime. This technique can be helpful in the oil and gas industry where it can be applied to microseismic events. The objective of this paper is to find double couple focal mechanisms, excluding scalar seismic moments, and the depths of small earthquakes using data from relatively few local stations. This objective is met by generating three‐component synthetic seismograms to match the observed normalized velocity seismograms. We first calculate Green's functions given an initial estimate of the earthquake's hypocentre, the locations of the seismic recording stations and a 1D velocity model of the region for a series of depths. Then, we calculate the moment tensor for different combinations of strikes, dips and rakes for each depth. These moment tensors are combined with the Green's functions and then convolved with a source time function to produce synthetic seismograms. We use a grid search to find the synthetic seismogram with the largest objective function that best fits all three components of the observed velocity seismogram. These parameters define the focal mechanism solution of an earthquake. We tested the method using three earthquakes in Southern California with moment magnitudes of 5.0, 5.1 and 4.4 using the frequency range 0.1–2.0 Hz. The source mechanisms of the events were determined independently using data from a multitude of stations. Our results obtained, from as few as three stations, generally match those obtained by the Southern California Earthquake Data Center. The main advantage of this method is that we use relatively high‐frequency full‐waveforms, including those from short‐period instruments, which makes it possible to find the focal mechanism and depth of earthquakes using as few as three stations when the velocity structure is known.     

用广义射线和有限差分计算近场理论地震图的混合方法

本文提出一种结合广义射线和有限差分理论而形成的混合方法（以下简称混合方法）．在介质均匀区（包括平行介质分层区）应用广义射线理论，在介质不均匀区应用有限差分理论．在这种结合过程中，把均匀区广义射线的结果作为不均匀区有限差分区波场连续的输入．对于均匀介质模型，混合方法理论地震图和广义射线理论地震图、广义反射透射系数矩阵及离散波数法地震图的对比，取得了满意的结果，在数值上证明了该方法的正确性．计算了１９９０年８月５日Ｈａｋｏｎｅ地震前震在日本Ａｓｈｉｇａｒａ山谷盲测点的响应，理论地震图和实际资料的比较同样取得好的结果．这种方法可用于地震勘探、工程地震、强地面运动的研究．     

A Full Waveform Test of the Southern California Velocity Model by the Reciprocity Method

— We apply the reciprocity method (Eisner and Clayton, 2001a) to compare the full waveform synthetic seismograms with a large number of observed seismograms. The reciprocity method used in the finite-difference modeling allows for the use of high quality data observed from the earthquakes distributed over the wide range of azimuths and depths. We have developed a methodology to facilitate the comparison between data and synthetics using a set of attributes to characterize the seismograms. These attributes are maximum amplitude, time delay and coda decay of the magnitude of the displacement vector. For the Southern California Velocity Model, Version 1 (Magistrale et al., 1996), we have found misfits between data and synthetics for paths traveling outside of the sedimentary basins and the western part of the Los Angeles and San Fernando basins.     

Inversion of seismograms to determine simultaneously the moment tensor components and source time function for a point source buried in a horizontally layered medium

Summary A method of determining simultaneously the moment tensor and source time function in the point source approximation is presented. For trial values of the moment tensor components and of the source time function, parametrized by the sum of overlapping triangles delayed in time, theoretical seismograms can be synthetized and compared with the recorded ones. The iterative procedure determines the adjustment of source parameters until a good correlation of both synthetic and observed records is reached. The Green functions in a horizontally stratified medium are constructed with the use of a modal summation method.The limits of applicability of the algorithm are illustrated by the inversion of four synthetic seismograms constructed for two horizontally stratified models of the structure in Friuli area, Italy. The records constructed for the same structural model as for which the Green functions were computed can be inverted even in the high-frequency range. In the opposite case, when the records and Green functions used corresponded to different structural models, a good correlation of the input records with the final synthetics was obtained for low - pass filtered data only.Additional tests performed with input seismograms contaminated with random noise yielded good resolution of the moment tensor and the duration of the source time function even for a high noise to signal ratio.     

Feasibility of waveform inversion of Rayleigh waves for shallow shear-wave velocity using a genetic algorithm

Conventional surface wave inversion for shallow shear (S)-wave velocity relies on the generation of dispersion curves of Rayleigh waves. This constrains the method to only laterally homogeneous (or very smooth laterally heterogeneous) earth models. Waveform inversion directly fits waveforms on seismograms, hence, does not have such a limitation. Waveforms of Rayleigh waves are highly related to S-wave velocities. By inverting the waveforms of Rayleigh waves on a near-surface seismogram, shallow S-wave velocities can be estimated for earth models with strong lateral heterogeneity. We employ genetic algorithm (GA) to perform waveform inversion of Rayleigh waves for S-wave velocities. The forward problem is solved by finite-difference modeling in the time domain. The model space is updated by generating offspring models using GA. Final solutions can be found through an iterative waveform-fitting scheme. Inversions based on synthetic records show that the S-wave velocities can be recovered successfully with errors no more than 10% for several typical near-surface earth models. For layered earth models, the proposed method can generate one-dimensional S-wave velocity profiles without the knowledge of initial models. For earth models containing lateral heterogeneity in which case conventional dispersion-curve-based inversion methods are challenging, it is feasible to produce high-resolution S-wave velocity sections by GA waveform inversion with appropriate priori information. The synthetic tests indicate that the GA waveform inversion of Rayleigh waves has the great potential for shallow S-wave velocity imaging with the existence of strong lateral heterogeneity.     

较复杂介质波场计算中的一种透射边界

传统的人工边界是在声波或弹性波分解为内行和外行分量的基础上设计的.对于较复杂的介质模型（如粘弹介质、弹塑介质、塑性介质模型等）,地震波不能简单地分解为各自满足其运动方程的纵波、横波等成分,且地震波在传播过程中还有衰减现象,因此传统的人工边界已不能有效地用于非弹性的较复杂介质的波场模拟.本文提出了一种适合于更一般的地震模型的波场计算的透射边界条件,并以粘弹介质的一个较简单的二维几何模型为例,通过有限元数值求解这种透射边界和刚性边界下粘弹波的激发和传播,得到地面合成地震记录,证明了这种透射边界用于较复杂介质波场计算是可行的.     

Numerical-analytical interfacing in two dimensions with applications to modeling NTS seismograms

A new method for interfacing numerical and integral techniques allows greater flexibility in seismic modeling. Specifically, numerical calculations in laterally varying structure are interfaced with analytic methods that enable propagation to great distances. Such modeling is important for studying situations containing localized complex regions not easily handled by analytic means. The calculations involved are entirely two-dimensional, but the use of an appropriate source in combination with a filter applied to the resulting seismograms produces synthetic seismograms which are point-source responses in three dimensions. The integral technique is called two-dimensional Kirchhoff because its form is similar to the classical three-dimensional Kirchhoff. Data from Yucca Flat at the Nevada Test Site are modeled as a demonstration of the usefulness of the new method. In this application, both local and teleseismic records are modeled simultaneously from the same model with the same finite-difference run. This application indicates the importance of locally scattered Rayleigh waves in the production of teleseismic body-wave complexity and coda.