面波频散反演的数值模拟     

李平  许厚泽  卢造勋  熊熊 《大地测量与地球动力学》2000,20(1):22-29

大量的数值模拟表明,SVD和LSQRD在面波频散网格反演两步法中的应用效果都很好.但SVD可以用分辨矩阵、信息矩阵和协方差矩阵对解估计进行数学上客观有效的评价;而对于大型稀疏方程组的求解,LSQRD确是一种内存需求小、计算速度快以及分辨抗噪能力都较强的算法 .在现有计算机运算速度较快、内存可以扩充较大的条件下,实测数据量不很大时,应采用SVD算法进行线性反演.  相似文献   

Analysis of the Sea Fog in the Sea Around the Great Wall Station,Antarctica     

黄耀荣  薛振和 《海洋通报(英文版)》2001,3(1)

The synoptic analysis of sea fog in western Antarctic sea region is made based on the observation data in the Chinese Antarctic station, Great Wall Station, from December 1994 to November 1995, and the facsimile weather charts issued by Chile. It is found that more than 90% fog in this region is the advection cooling fog. Also, the synoptic mechanism of the fog creation and distinction is discussed by analyzing the pressure field, the temperature field and the upperlevel stratification. Finally, the focus of attention in forecasting fog is pointed out.  相似文献   

Highly efficient iterative methods for solving linear equations of three-dimensional sphere discontinuous deformation analysis     

Gang-Hai Huang  Yuan-Zhen Xu  Xiong-Wei Yi  Ming Xia  Yu-Yong Jiao  Shu Zhang 《国际地质力学数值与分析法杂志》2020,44(9):1301-1314

The efficiency of solving equations plays an important role in implicit-scheme discontinuous deformation analysis (DDA). A systematic investigation of six iterative methods, namely, symmetric successive over relaxation (SSOR), Jacobi (J), conjugate gradient (CG), and three preconditioned CG methods (ie, J-PCG, block J-PCG [BJ-PCG], and SSOR-PCG), for solving equations in three-dimensional sphere DDA (SDDA) is conducted in this paper. Firstly, simultaneous equations of the SDDA and iterative formats of the six solvers are presented. Secondly, serial and OpenMP-based parallel computing numerical tests are done on a 16-core PC, the result of which shows that (a) for serial computing, the efficiency of the solvers is in this order: SSOR-PCG > BJ-PCG > J-PCG > SSOR>J > CG, while for parallel computing, BJ-PCG is the best solver; and (b) CG is not only the most sensitive to the ill-condition of the equations but also the most time consuming under both serial and parallel computing. Thirdly, to estimate the effects of equation solvers acting on SDDA computations, an application example with 10 000 spheres and 200 000 calculation steps is simulated on this 16-core PC using serial and parallel computing. The result shows that SSOR-PCG is about six times faster than CG for serial computing, while BJ-PCG is about four times faster than CG for parallel computing. On the other hand, the whole computation time using BJ-PCG for parallel computing is 3.37 hours (ie, 0.061 s per step), which is about 36 times faster than CG for serial computing. Finally, some suggestions are given based on this investigation result.  相似文献   

Iterative seismic inversion   总被引：4，自引：0，他引：4  

Stephen J. Norton 《Geophysical Journal International》1988,94(3):457-468

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用水准测量资料反演1990年青海共和地震的震源机制     

赵明  陈运泰  巩守文  王庆良 《大地测量与地球动力学》1992,(4)

利用地面垂直形变测量资料研究了1990年4月26日青海共和Ms6.9地震的震源机制。通过反演得出这次地震是由逆冲倾滑为主的断层错动引起的。该断层走向102°,倾向SW,倾角46°,长40km,宽9km,断层上部边界至地面的垂直距离3km,下部边界至地面的垂直距离10km。逆冲倾滑错距79cm,伴以错距5cm的左旋走向滑动。这是一次低应力降(3.8MPa)的板内地震,应变降为5.7×10~(-5),地震矩9.8×10~(18)N°m,能量释放5.0×10~(14)J。由反演得到的共和地震的震源机制与等震线的形态、余震的空间分布以及共和盆地断层交汇的特征总体上是一致的。  相似文献   

Inversion of temperature measurements in lake sediment     

P. Y. Shen  A. E. Beck 《Geophysical Journal International》1988,94(3):545-558

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Linear programming approach to moment tensor inversion of earthquake sources and some tests on the three-dimensional structure of the upper mantle     

Toshiro Tanimoto  Hiroo Kanamori 《Geophysical Journal International》1986,84(2):413-430

Summary. A new method of moment tensor inversion is developed, which combines surface wave data and P -wave first motion data in a linear programming approach. Once surface wave spectra and first motion data are given, the method automatically obtains the solution that satisfies first motion data and minimizes the L1 norm of the surface wave spectra. We show the results of eight events in which the method works and is stable even for shallow events. We also show one event in which surface wave data and P -wave first motion data seem to be incompatible. In such cases, our method does not converge or converges to a solution which has a large minor (second) double couple component. It is an advantage that the method can determine the compatibility of two data sets without trial and error.
Laterally heterogeneous phase velocity corrections are used to obtain spectra at the source. The method is also applied to invert moment tensors of eight events in two recent three-dimensional (3-D) upper mantle structures. In both 3-D models, variances of spectra are smaller than those in a laterally homogeneous model at 256 s. Statistical tests show that those reductions are significant at a high confidence level for five events out of eight examined. For three events, we examined those reductions at shorter periods, 197 and 151 s. The reduction of variances is comparable to the results at 256 s and is again statistically significant at a high confidence level. Orientation of fault planes does not change very much by incorporation of lateral variations of phase velocity or by doing inversions at different periods. This is mainly because of the constraints from P -wave first motion data. Scatter of phase spectra at shorter periods, especially at 151 s, is great and suggests that surface wave ray paths deviate from great circle paths substantially and these effects cannot be ignored.  相似文献   

Anelastic Rayleigh Wave Attenuation In the Iberian Peninsula   总被引：1，自引：0，他引：1  

Jose A. Canas  Fernando De  Miguel†  Francisco Vidal†  Gerardo Alguacil† 《Geophysical Journal International》1988,95(2):391-396

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Non-Linear Reflection Tomography   总被引：6，自引：0，他引：6  

V. Farra  R. Madariaga 《Geophysical Journal International》1988,95(1):135-147

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A Variable Slip Fault Model For the 1908 Messina Straits (Italy) Earthquake, By Inversion of Levelling Data   总被引：1，自引：0，他引：1  

Giuseppe De  Natale Folco Pingue 《Geophysical Journal International》1991,104(1):73-84

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