Seismic exploration‐scale velocities and structure from ambient seismic noise (>1 Hz)
Seismic exploration‐scale velocities and structure from ambient seismic noise (>1 Hz)
复制标题
DOI：
10.1002/jgrb.50339
复制
发表时间：
2013-08
期刊：
影响因子：
--
通讯作者：
D. Draganov;X. Campman;J. Thorbecke;A. Verdel;K. Wapenaar
中科院分区：
文献类型：
--
作者：
D. Draganov;X. Campman;J. Thorbecke;A. Verdel;K. Wapenaar
在固体地震学中使用长时间相关性和随后的地壳层析成像成功地恢复了面波，这引发了人们对从勘探地震学中的噪声中提取地下信息的兴趣。勘探地震学中的地下信息通常来源于大于1 Hz的体波反射，这对于利用环境噪声是具有挑战性的。我们使用11小时的噪音记录在苏尔特盆地，利比亚。首先，我们研究了噪声的特性。我们表明，大部分的噪声是由表面波在低于6赫兹的频率。一些噪声面板包含几乎垂直传播的事件。我们进一步表征这些事件使用波束形成算法。从波束形成，我们得出结论，这些事件表示具有相当丰富的方位角分布的体波到达。在噪声中具有体波到达是体波反射恢复的先决条件。我们将记录的环境噪声面板进行互相关和求和，以检索共源道集，采用两种方法-使用所有噪声和仅使用可能有助于反射检索的包含体波到达的噪声面板。将反演道集与活动地震数据进行比较，我们发现，几个反演同相轴在短炮检距处的双向旅行时与活动数据中的反射波的双向旅行时相一致，因此对应于反射波的顶点。然后，我们将从两种方法中检索的地下叠加部分与活动数据叠加部分进行比较，并显示反射层沿沿着是一致的。第二种方法的结果更好地展示了反射器。
The successful surface waves retrieval in solid‐Earth seismology using long‐time correlations and subsequent tomographic images of the crust have sparked interest in extraction of subsurface information from noise in the exploration seismology. Subsurface information in exploration seismology is usually derived from body‐wave reflections > 1 Hz, which is challenging for utilization of ambient noise. We use 11 h of noise recorded in the Sirte basin, Libya. First, we study the characteristics of the noise. We show that the bulk of the noise is composed of surface waves at frequencies below 6 Hz. Some noise panels contain nearly vertically traveling events. We further characterize these events using a beamforming algorithm. From the beamforming, we conclude that these events represent body‐wave arrivals with a fairly rich azimuthal distribution. Having body‐wave arrivals in the noise is a prerequisite for body‐wave reflections retrieval. We crosscorrelate and sum the recorded ambient‐noise panels to retrieve common‐source gathers, following two approaches—using all the noise and using only noise panels containing body‐wave arrivals likely to contribute to the reflections retrieval. Comparing the retrieved gathers with active seismic data, we show that the two‐way traveltimes at short offsets of several retrieved events coincide with those of reflections in the active data and thus correspond to apexes of reflections. We then compare retrieved stacked sections of the subsurface from both approaches with the active‐data stacked section and show that the reflectors are consistent along a line. The results from the second approach exhibit the reflectors better.