利用基于密集台阵的面波成像方法研究南北地震带北段地壳上地幔速度结构
发布时间：2018-12-14 20:06
【摘要】：南北地震带北段位于青藏高原东北缘,包含阿拉善块体、鄂尔多斯块体、青藏块体和四川盆地等多个活动块体。这些块体,尤其是它们的交界部位,具有十分复杂的结构。本文首先利用在天水布设的较小型台阵,对数据做空间自相关来提取频散曲线,采用传统成像方法得到地下50 m内浅层速度结构;之后应用背景噪声面波成像方法,背景噪声面波周期较短,路径覆盖密集,获得10~22 s的群速度和相速度信息;近年来,随着越来越多密集台阵的布设,延伸出一些基于密集台阵的新方法,如程函方程成像和赫姆霍兹成像。利用这种方法,得到20~70 s面波相速度图及各向异性信息;地震中面波周期较长,此地区比较复杂,需要对浅层速度做约束,而对10 km以上更浅层信息,需要通过面波另外一个特性进行解释。通过计算得到相同周期下,振幅纵横比反映深度大小的信息,但密集台阵数据过多,九分量NCF计算量更大,利用云计算的方法,大大节省了计算的时间。本文主要包括以下几点:(1)为了对比天然源面波勘探不同台阵布局的探测效果,筛选出探测成果可靠、效率高和便于野外施工的天然源面波勘探台阵阵形,我们在天水市黄土覆盖区的同一场地分别用4种常见的阵形进行了数据采集试验,并对各种阵形数据用SPAC或ESPAC方法提取了相应的频散曲线,通过反演得到了试验点地下的浅层速度结构模型。分析对比试验结果表明:4种台阵提取的频散曲线数值很相近;频散谱能量集中度较高的是嵌套式等边三角形和圆形台阵,L形和直线形相对分散;L形低频段(4~8 Hz)比直线形差,高频段(8~40 Hz)比直线形好。针对直线形排列在高频段信噪比较低的情况,在确保探测成果可靠的前提下,为了提高探测效率,提出了在同一直线形排列上开展天然源和人工源面波联合勘探的数据采集方法。实验结果证实:这种联合方法不仅可弥补直线形高频段的不足,确保探测精度和结果的可靠性,而且还能做到"高低"频兼顾,即"深浅"兼顾。(2)南北地震带北段位于东昆仑断裂带东段以北的青藏高原东北隅构造区,是研究青藏高原东北缘同周边块体相互作用的重要区域,也是研究大陆块体强震孕育模式的重要试验场。本文利用2013年12月到2015年5月密集台阵记录的数据,通过互相关方法提取瑞利波的经验格林函数,利用相匹配滤波的时频分析技术测量瑞利波相速度频散曲线。采用背景噪声面波成像方法得到南北地震带北段地区10~22 s的瑞利波群速度和相速度分布图,结果较好地匹配了块体边界及断层走向。(3)目前面波层析成像是研究地壳上地幔结构的重要方法,并且随着密集台阵的布设,出现了一些基于密集台阵的面波层析成像新方法。本文利用南北地震带北段密集台阵数据,通过自动获取面波相速度方法(ASWMS),得到20~70 s的瑞利面波相速度分布图像及方位各项异性。通过将本文结果和前人研究成果相结合,对南北地震带北段区域的低速层分布、活动块体边界及变形信息有了更深的认识。联合两种基于台阵的成像方法,可以使我们获得较为完备的壳幔结构,从而可以对该区的活动地块分界及其相互作用有较为深入的认识。(4)随着背景噪声研究的发展,九分量背景噪声互相关函数得到越来越多的应用。然而,大规模密集台站往往产生海量的数据集合,利用这些数据计算九分量噪声互相关函数的计算量过大,难以在传统计算模式下快速完成。本文提出一种基于云计算的九分量噪声互相关函数的计算方法,可以利用弹性的云计算服务,实现海量噪声互相关函数计算的分解和加速。我们将此技术应用于"中国地震科学台阵探测 南北地震带北段"674个宽频带台站2014 2015年的三分量连续记录,获取了所有台站间的九分量噪声互相关函数。总体计算共完成了约22万条台站对路径上近14.9亿条单天互相关函数的计算,整体平均耗时约为10.2小时。完成等量计算,传统计算模式需要耗时近6个月,基于云计算的NCF计算技术实现了近400倍的增速,并可以弹性地扩充。我们分析了所得九分量噪声互相关函数中瑞利面波的ZH振幅比,并同天然地震中瑞利面波的振幅比进行了比较,验证了计算结果的可靠性。基于云计算的噪声互相关函数计算方法,为利用现代计算技术处理海量数据提供了重要参考。
[Abstract]:The northern section of the north-south seismic belt is located in the northeast of the Qinghai-Tibet Plateau, including the Alashan block, the Ordos block, the Qinghai-Tibet block and the Sichuan Basin. These blocks, in particular their junction, have a very complex structure. In this paper, the small stage array in Tianshui is used to extract the frequency dispersion curve from the space self-correlation of the data, and the shallow velocity structure in the underground 50 m is obtained by the conventional imaging method. The background noise surface wave imaging method is then applied, the surface wave period of the background noise is shorter and the path coverage is dense, The group velocity and phase velocity information of 10 to 22 s are obtained. In recent years, with the arrangement of more and more dense sets, some new methods based on dense array are extended. With this method, the velocity map and the anisotropic information of 20-70 s surface wave are obtained; the surface wave period in the earthquake is longer, the region is more complex, the shallow velocity is required to be restrained, and the shallow information above 10 km needs to be explained by another characteristic of the surface wave. in that same period, the amplitude and the aspect ratio reflect the information of the depth size, but the data of the dense stage array is too many, the calculation amount of the nine-component NCF is larger, and the method of the cloud calculation is utilized, so that the calculation time is greatly saved. The method mainly includes the following steps: (1) in order to compare the detection effect of different array layout of the natural source surface wave, the natural source surface wave exploration platform array with reliable detection result, high efficiency and convenient field construction is screened, In the same field of the loess-covered area of Tianshui City, the data acquisition test is carried out in four common forms, and the corresponding frequency dispersion curves are extracted by the SPAC or ESPAC method for various formation data, and the shallow velocity structure model of the subsurface of the test point is obtained by inversion. The results of the analysis and comparison show that the numerical values of the frequency dispersion curves extracted from the four matrix arrays are very similar; the energy concentration of the frequency dispersion spectrum is higher than that of the nested equilateral triangle and the circular table array, and the L-shape and the straight line form are relatively dispersed; and the L-shaped low-frequency section (4-8 Hz) is smaller than the straight-line shape, The high frequency band (8 ~ 40 Hz) is better than the straight line. In order to improve the detection efficiency, the data acquisition method for joint exploration of natural source and artificial source surface wave in the same linear arrangement is proposed in order to improve the detection efficiency. The experimental results confirm that the combined method can not only make up the shortage of the high frequency band of the straight line, ensure the reliability of the detection precision and the result, but also can achieve the "high and low"-frequency balance, that is, the "depth" balance. (2) The northern section of the north-south seismic belt is located in the northeast corner of the Qinghai-Tibet Plateau, north of the east section of the East Kunlun fault zone. It is an important area for studying the interaction between the northeast margin of the Qinghai-Tibet Plateau and the surrounding block. It is also an important test ground for studying the model of strong earthquake in the continental block. This paper uses the data from December 2013 to May 2015 to extract the Rayleigh wave's experience Green's function by means of cross-correlation method, and uses the matched filtering time-frequency analysis technique to measure the Rayleigh wave phase velocity dispersion curve. The Rayleigh wave group velocity and phase velocity profile of 10-22 s in the northern section of the North-South seismic belt are obtained by the background noise surface wave imaging method. The results show that the block boundary and the fault direction are well matched. (3) The current surface wave tomography is an important method to study the geotectonic structure of the earth's crust, and with the arrangement of the dense stage array, some new methods of surface wave tomography based on dense array are presented. In this paper, by means of automatic acquisition of surface wave phase velocity method (ASWMS), the velocity distribution and azimuth of Rayleigh surface wave of 20 to 70 s are obtained by means of automatic acquisition of surface wave phase velocity method (ASWMS). By combining the results of this paper with the previous research results, the low-velocity layer distribution, the moving block boundary and the deformation information of the northern section of the north-south seismic belt are more and more recognized. Combining the two imaging methods based on the array matrix, we can get a complete shell structure, so we can understand the boundary and interaction of the movable plot in this area. (4) With the development of background noise research, the cross-correlation function of nine-component background noise gets more and more application. However, large-scale dense stations tend to generate a large set of data, and the calculation of the cross-correlation function of the nine-component noise by using these data is too large to be quickly completed in the traditional calculation mode. In this paper, a method for calculating the cross-correlation function of nine-component noise based on cloud computing is presented. The elastic cloud computing service can be used to realize the decomposition and acceleration of the mass noise cross-correlation function calculation. We apply this technique to the three-component continuous record of "涓浗鍦伴渿绉戝鍙伴樀鎺㈡祴 鍗楀寳鍦伴渿甯﹀寳娈，
本文编号：2379238
[Abstract]:The northern section of the north-south seismic belt is located in the northeast of the Qinghai-Tibet Plateau, including the Alashan block, the Ordos block, the Qinghai-Tibet block and the Sichuan Basin. These blocks, in particular their junction, have a very complex structure. In this paper, the small stage array in Tianshui is used to extract the frequency dispersion curve from the space self-correlation of the data, and the shallow velocity structure in the underground 50 m is obtained by the conventional imaging method. The background noise surface wave imaging method is then applied, the surface wave period of the background noise is shorter and the path coverage is dense, The group velocity and phase velocity information of 10 to 22 s are obtained. In recent years, with the arrangement of more and more dense sets, some new methods based on dense array are extended. With this method, the velocity map and the anisotropic information of 20-70 s surface wave are obtained; the surface wave period in the earthquake is longer, the region is more complex, the shallow velocity is required to be restrained, and the shallow information above 10 km needs to be explained by another characteristic of the surface wave. in that same period, the amplitude and the aspect ratio reflect the information of the depth size, but the data of the dense stage array is too many, the calculation amount of the nine-component NCF is larger, and the method of the cloud calculation is utilized, so that the calculation time is greatly saved. The method mainly includes the following steps: (1) in order to compare the detection effect of different array layout of the natural source surface wave, the natural source surface wave exploration platform array with reliable detection result, high efficiency and convenient field construction is screened, In the same field of the loess-covered area of Tianshui City, the data acquisition test is carried out in four common forms, and the corresponding frequency dispersion curves are extracted by the SPAC or ESPAC method for various formation data, and the shallow velocity structure model of the subsurface of the test point is obtained by inversion. The results of the analysis and comparison show that the numerical values of the frequency dispersion curves extracted from the four matrix arrays are very similar; the energy concentration of the frequency dispersion spectrum is higher than that of the nested equilateral triangle and the circular table array, and the L-shape and the straight line form are relatively dispersed; and the L-shaped low-frequency section (4-8 Hz) is smaller than the straight-line shape, The high frequency band (8 ~ 40 Hz) is better than the straight line. In order to improve the detection efficiency, the data acquisition method for joint exploration of natural source and artificial source surface wave in the same linear arrangement is proposed in order to improve the detection efficiency. The experimental results confirm that the combined method can not only make up the shortage of the high frequency band of the straight line, ensure the reliability of the detection precision and the result, but also can achieve the "high and low"-frequency balance, that is, the "depth" balance. (2) The northern section of the north-south seismic belt is located in the northeast corner of the Qinghai-Tibet Plateau, north of the east section of the East Kunlun fault zone. It is an important area for studying the interaction between the northeast margin of the Qinghai-Tibet Plateau and the surrounding block. It is also an important test ground for studying the model of strong earthquake in the continental block. This paper uses the data from December 2013 to May 2015 to extract the Rayleigh wave's experience Green's function by means of cross-correlation method, and uses the matched filtering time-frequency analysis technique to measure the Rayleigh wave phase velocity dispersion curve. The Rayleigh wave group velocity and phase velocity profile of 10-22 s in the northern section of the North-South seismic belt are obtained by the background noise surface wave imaging method. The results show that the block boundary and the fault direction are well matched. (3) The current surface wave tomography is an important method to study the geotectonic structure of the earth's crust, and with the arrangement of the dense stage array, some new methods of surface wave tomography based on dense array are presented. In this paper, by means of automatic acquisition of surface wave phase velocity method (ASWMS), the velocity distribution and azimuth of Rayleigh surface wave of 20 to 70 s are obtained by means of automatic acquisition of surface wave phase velocity method (ASWMS). By combining the results of this paper with the previous research results, the low-velocity layer distribution, the moving block boundary and the deformation information of the northern section of the north-south seismic belt are more and more recognized. Combining the two imaging methods based on the array matrix, we can get a complete shell structure, so we can understand the boundary and interaction of the movable plot in this area. (4) With the development of background noise research, the cross-correlation function of nine-component background noise gets more and more application. However, large-scale dense stations tend to generate a large set of data, and the calculation of the cross-correlation function of the nine-component noise by using these data is too large to be quickly completed in the traditional calculation mode. In this paper, a method for calculating the cross-correlation function of nine-component noise based on cloud computing is presented. The elastic cloud computing service can be used to realize the decomposition and acceleration of the mass noise cross-correlation function calculation. We apply this technique to the three-component continuous record of "涓浗鍦伴渿绉戝鍙伴樀鎺㈡祴 鍗楀寳鍦伴渿甯﹀寳娈，
本文编号：2379238
本文链接：https://www.wllwen.com/kejilunwen/diqiudizhi/2379238.html
