用Pg波走时重建华北地区结晶基底速度及时间项图像
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摘要
应用层析成象反投影方法，对华北地区28条深地震测深剖面Pg波走时进行处理，作出了该区结晶基底速度及时间项成象。并作了方法的数值模型合成数据的敏感性分析，证明所采用方法的有效性及成象结果的可靠性。计算中应用LSQR算法求解大型稀疏超定方程。并采用只存储矩阵非零元素技术，使存储量减小到原矩阵的百分之一，同时零元素不参加计算，提高了运算速度。华北地区结晶基底速度为5.9～6.35km／s，时间项最大为2.0s。
The crystal basement velocities and time-terms in North China region are imaged by a tomographic backprojection using Pg waves from 28 pro filles. Quantitative analyses of the algorithms are given by synthetic data of the digital model. The results from the test show that our method is quite stable and reliable. The LSQR algorithm is used for solving overdetermined equations. The zero elements of the large sparse matrix are not stored and calculated. Thus the store amount is reduced to one percent. The speed of calculation is raised greatly. The minimum and maximum velocities are 5. 9km/s and 6. 35km/s respectively. The maximum time-term is 2.0 second.
The crystal basement velocities and time-terms in North China region are imaged by a tomographic backprojection using Pg waves from 28 pro filles. Quantitative analyses of the algorithms are given by synthetic data of the digital model. The results from the test show that our method is quite stable and reliable. The LSQR algorithm is used for solving overdetermined equations. The zero elements of the large sparse matrix are not stored and calculated. Thus the store amount is reduced to one percent. The speed of calculation is raised greatly. The minimum and maximum velocities are 5. 9km/s and 6. 35km/s respectively. The maximum time-term is 2.0 second.
引文
1 Scheidegger, A.E and P. L.Willmore,1957, The use of a least squares method for the interpretation of data from seismic surveys Geophysics,V. 22, pp. 9—22.
2 Smith,T,et al,1996,lake Superiore crustal structure,J.G.R,V.71,pp.1141—1172.
3 Hearn,T. M. and R. W.Clayton, 1986, Lateral velocity variattons in Southern California,I. Results for the upper Crust from Pg Waves,Bull.Seism Soc.Am.,V.76.pp.2,459—509
4 Notet, G,1985,Soiving or resolving inadequate and noisy tomographic systems,J.Comp. phys., 61, 463-482
5 刘福田,曲克信,吴华,李强,刘建华,胡戈.华北地区地震层面成像.地球物理学报, 1985, 29(5): 442-449
6 孙若昧,刘福田.京津唐地区地壳结构与强震发生-I.P波速度结构.地球物理学报,1993,38,599—608.
2 Smith,T,et al,1996,lake Superiore crustal structure,J.G.R,V.71,pp.1141—1172.
3 Hearn,T. M. and R. W.Clayton, 1986, Lateral velocity variattons in Southern California,I. Results for the upper Crust from Pg Waves,Bull.Seism Soc.Am.,V.76.pp.2,459—509
4 Notet, G,1985,Soiving or resolving inadequate and noisy tomographic systems,J.Comp. phys., 61, 463-482
5 刘福田,曲克信,吴华,李强,刘建华,胡戈.华北地区地震层面成像.地球物理学报, 1985, 29(5): 442-449
6 孙若昧,刘福田.京津唐地区地壳结构与强震发生-I.P波速度结构.地球物理学报,1993,38,599—608.
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