second trace echo

例句：

1. 1. The team used a new technique to detect the second trace echoes of the earthquake.
   该团队使用了一种新的技术来探测地震的二次追踪回声。
2. 2. The researcher found that the second trace echoes could be used to improve the accuracy of seismic detection.
   研究人员发现，二次追踪回声可以用来提高地震检测的准确性。
3. 3. In this experiment, we aimed to understand the second trace echoes in the ocean waves.
   在这个实验中，我们的目标是理解海洋波浪中的二次追踪回声。