1.5D inversion of lateral variation of Scholte-wave dispersion
1.5D inversion of lateral variation of Scholte-wave dispersion
复制标题
DOI：
10.1190/1.1707052
复制
发表时间：
2004-03-01
期刊：
影响因子：
3.3
通讯作者：
Theilen, F
中科院分区：
文献类型：
--
作者：
Bohlen, T;Kugler, S;Theilen, F
浅水海洋沉积物现场剪切波速度的可靠模型对于岩土工程应用、岩性沉积物表征和地震勘探研究是重要的。从Scholte波频散的横向变化推断了浅海沉积物的二维横波速度结构。Scholte波记录在一个普通的接收器收集产生的气枪拖在船后面远离一个固定的海底地震仪。偏移距窗口沿着公共接收器道集移动以拾取局部波场。倾斜叠加产生局部波场的慢度频谱，其中包含气枪激发的所有模式。局部频谱中的振幅最大值（色散曲线）被拾取并反转为位于窗口中心的剪切波速度深度剖面。当窗口沿共接收道集连续沿着移动时，生成2D剪切波速度剖面。在一个合成的例子中，地面剪切波速度的平滑横向变化被很好地重建。该方法适用于两个正交的共同接收机采集在波罗的海（北方德国）。反演的2D模型显示了海底剪切波速度的强烈垂直梯度。沿着一个剖面，在海底附近观察到显著的横向变化。
Reliable models of in-situ shear-wave velocities of shallow-water marine sediments are important for geotechnical applications, lithological sediment characterization, and seismic exploration studies. We infer the 2D shear-wave velocity structure of shallow-water marine sediments from the lateral variation of Scholte-wave dispersion. Scholte waves are recorded in a common receiver gather generated by an air gun towed behind a ship away from a single stationary ocean-bottom seismometer. An offset window moves along the common receiver gather to pick up a local wavefield. A slant stack produces a slowness-frequency spectrum of the local wavefield, which contains all modes excited by the air gun. Amplitude maxima (dispersion curves) in the local spectrum are picked and inverted for the shear-wave velocity depth profile located at the center of the window. As the window continuously moves along the common receiver gather, a 2D shear-wave velocity section is generated. In a synthetic example the smooth lateral variation of surficial shear-wave velocity is well reconstructed. The method is applied to two orthogonal common receiver gathers acquired in the Baltic Sea (northern Germany). The inverted 2D models show a strong vertical gradient of shear-wave velocity at the sea floor. Along one profile significant lateral variation near the sea floor is observed.