Acta Geophysica ( IF 2.3 ) Pub Date : 2020-10-09 , DOI: 10.1007/s11600-020-00494-1 Xian-Xiang Wang , Ju-Zhi Deng , Jing-Li Ren
In CSAMT exploration, the using of the artificial sources not only improves the signal-to-noise ratio of the data, but also brings a series of distortion effects, such as shadow and source overprint effects. This paper attempts to introduce a distortion effect caused by the target in the survey area. Although it is often ignored, it always plagues the data interpretation. In CSAMT method, the primary current has determined direction due to the source. When the primary current encounters electrical interfaces, the induced charge will accumulate on it and generate local current, causing local distortion. The anomaly body stretches in the direction of the vertical primary current, and a false anomaly with opposite polarity appears on both sides of the target. If the direction of the primary current is different, the accumulation position of the induced charge is also different, which will result in different shapes of the anomalies in observed data. This paper confirms the existence of the distortion by taking four simple models as examples and explains it from the physical mechanism. On this basis, the paper summarizes the relationship between inversion and distortion. If our code can simulate the distortion effect in the forward, we do not need to remove it before the inversion. Otherwise, it must be removed.
中文翻译:
CSAMT探测中目标异常体引起的失真效应
在CSAMT勘探中,人工源的使用不仅提高了数据的信噪比,而且带来了一系列失真效应,例如阴影和源套印效应。本文尝试介绍由调查区域中的目标引起的失真效果。尽管它经常被忽略,但它总是困扰着数据解释。在CSAMT方法中,由于电流的缘故,初级电流已确定方向。当初级电流遇到电接口时,感应电荷将在其上积累并产生局部电流,从而引起局部畸变。异常体沿垂直初级电流的方向伸展,目标的两侧出现极性相反的虚假异常。如果一次电流的方向不同,感应电荷的积累位置也不同,这将导致观测数据中异常的形状不同。本文以四个简单的模型为例,确认了畸变的存在,并从物理机理进行了解释。在此基础上,本文总结了反演与失真之间的关系。如果我们的代码可以模拟向前的失真效果,则无需在反转之前将其删除。否则,必须将其删除。如果我们的代码可以模拟向前的失真效果,则无需在反转之前将其删除。否则,必须将其删除。如果我们的代码可以模拟向前的失真效果,则无需在反转之前将其删除。否则,必须将其删除。