【摘要】：南北地震帶北段位于青藏高原東北緣,包含阿拉善塊體、鄂爾多斯塊體、青藏塊體和四川盆地等多個活動塊體。這些塊體,尤其是它們的交界部位,具有十分復雜的結構。本文首先利用在天水布設的較小型臺陣,對數(shù)據(jù)做空間自相關來提取頻散曲線,采用傳統(tǒng)成像方法得到地下50 m內淺層速度結構;之后應用背景噪聲面波成像方法,背景噪聲面波周期較短,路徑覆蓋密集,獲得10~22 s的群速度和相速度信息;近年來,隨著越來越多密集臺陣的布設,延伸出一些基于密集臺陣的新方法,如程函方程成像和赫姆霍茲成像。利用這種方法,得到20~70 s面波相速度圖及各向異性信息;地震中面波周期較長,此地區(qū)比較復雜,需要對淺層速度做約束,而對10 km以上更淺層信息,需要通過面波另外一個特性進行解釋。通過計算得到相同周期下,振幅縱橫比反映深度大小的信息,但密集臺陣數(shù)據(jù)過多,九分量NCF計算量更大,利用云計算的方法,大大節(jié)省了計算的時間。本文主要包括以下幾點:(1)為了對比天然源面波勘探不同臺陣布局的探測效果,篩選出探測成果可靠、效率高和便于野外施工的天然源面波勘探臺陣陣形,我們在天水市黃土覆蓋區(qū)的同一場地分別用4種常見的陣形進行了數(shù)據(jù)采集試驗,并對各種陣形數(shù)據(jù)用SPAC或ESPAC方法提取了相應的頻散曲線,通過反演得到了試驗點地下的淺層速度結構模型。分析對比試驗結果表明:4種臺陣提取的頻散曲線數(shù)值很相近;頻散譜能量集中度較高的是嵌套式等邊三角形和圓形臺陣,L形和直線形相對分散;L形低頻段(4~8 Hz)比直線形差,高頻段(8~40 Hz)比直線形好。針對直線形排列在高頻段信噪比較低的情況,在確保探測成果可靠的前提下,為了提高探測效率,提出了在同一直線形排列上開展天然源和人工源面波聯(lián)合勘探的數(shù)據(jù)采集方法。實驗結果證實:這種聯(lián)合方法不僅可彌補直線形高頻段的不足,確保探測精度和結果的可靠性,而且還能做到"高低"頻兼顧,即"深淺"兼顧。(2)南北地震帶北段位于東昆侖斷裂帶東段以北的青藏高原東北隅構造區(qū),是研究青藏高原東北緣同周邊塊體相互作用的重要區(qū)域,也是研究大陸塊體強震孕育模式的重要試驗場。本文利用2013年12月到2015年5月密集臺陣記錄的數(shù)據(jù),通過互相關方法提取瑞利波的經(jīng)驗格林函數(shù),利用相匹配濾波的時頻分析技術測量瑞利波相速度頻散曲線。采用背景噪聲面波成像方法得到南北地震帶北段地區(qū)10~22 s的瑞利波群速度和相速度分布圖,結果較好地匹配了塊體邊界及斷層走向。(3)目前面波層析成像是研究地殼上地幔結構的重要方法,并且隨著密集臺陣的布設,出現(xiàn)了一些基于密集臺陣的面波層析成像新方法。本文利用南北地震帶北段密集臺陣數(shù)據(jù),通過自動獲取面波相速度方法(ASWMS),得到20~70 s的瑞利面波相速度分布圖像及方位各項異性。通過將本文結果和前人研究成果相結合,對南北地震帶北段區(qū)域的低速層分布、活動塊體邊界及變形信息有了更深的認識。聯(lián)合兩種基于臺陣的成像方法,可以使我們獲得較為完備的殼幔結構,從而可以對該區(qū)的活動地塊分界及其相互作用有較為深入的認識。(4)隨著背景噪聲研究的發(fā)展,九分量背景噪聲互相關函數(shù)得到越來越多的應用。然而,大規(guī)模密集臺站往往產(chǎn)生海量的數(shù)據(jù)集合,利用這些數(shù)據(jù)計算九分量噪聲互相關函數(shù)的計算量過大,難以在傳統(tǒng)計算模式下快速完成。本文提出一種基于云計算的九分量噪聲互相關函數(shù)的計算方法,可以利用彈性的云計算服務,實現(xiàn)海量噪聲互相關函數(shù)計算的分解和加速。我們將此技術應用于"中國地震科學臺陣探測 南北地震帶北段"674個寬頻帶臺站2014 2015年的三分量連續(xù)記錄,獲取了所有臺站間的九分量噪聲互相關函數(shù)。總體計算共完成了約22萬條臺站對路徑上近14.9億條單天互相關函數(shù)的計算,整體平均耗時約為10.2小時。完成等量計算,傳統(tǒng)計算模式需要耗時近6個月,基于云計算的NCF計算技術實現(xiàn)了近400倍的增速,并可以彈性地擴充。我們分析了所得九分量噪聲互相關函數(shù)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進行了比較,驗證了計算結果的可靠性。基于云計算的噪聲互相關函數(shù)計算方法,為利用現(xiàn)代計算技術處理海量數(shù)據(jù)提供了重要參考。
[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浗鍦伴渿縐戝鍙伴樀鎺㈡祴 鍗楀寳鍦伴渿甯﹀寳孌，

本文編號：2379238