The proliferation of nuclear tests is a problem that threatens the safety and health of everybody. In order to tackle this problem, the UN is promoting the Comprehensive Nuclear-Test-Ban Treaty (CTBT), which includes protocols for monitoring and On-Site Inspections (OSI). The purpose of OSI is to verify if a nuclear test has been carried out by identifying with a geophysical technique the presence of a cavern, hole or some device that indicates the violation of the treaty. In this context, it is desirable to be able to use exploration-seismology techniques to detect caverns created by an underground nuclear explosion. However, there is scarce information about the seismic signature of this type of cavern. We present the results of elastic wave propagation simulations, in the time domain, with a cavern created by an underground nuclear explosion. The wave equation is solved using the spectral element method with 4th order basis functions and quadrilateral elements. We show the results for models with cavities and caverns corresponding to explosions of 1, 20 and 100 kilotons, and obtain seismic traces in which we can observe the effect of the structures. We conclude that caverns created by nuclear explosions can be detected using seismic data and distinguished from caves because they behave like two concentric diffractor bodies, as opposed to caves-like diffractors.

中文翻译：

---

二维勘探地震数据中地下核爆炸产生的洞穴的理论特征

核试验的扩散是一个威胁着所有人安全与健康的问题。为了解决这个问题，联合国正在促进《全面禁止核试验条约》（CTBT），其中包括监测和现场视察（OSI）协议。OSI的目的是通过使用地球物理技术识别是否存在表明违反条约的洞穴，洞口或某些装置来验证是否进行了核试验。在这种情况下，希望能够使用勘探地震学技术来探测由地下核爆炸产生的洞穴。但是，关于这种洞穴的地震特征的信息很少。我们介绍了在时域中由地下核爆炸产生的洞穴产生的弹性波传播模拟的结果。使用具有四阶基函数和四边形元素的频谱元素方法来求解波动方程。我们显示了具有对应于1、20和100千克爆炸的空洞和洞穴的模型的结果，并获得了地震迹线，可以在其中观察结构的影响。我们得出的结论是，可以使用地震数据检测由核爆炸产生的洞穴，并将其与洞穴区分开来，因为它们的行为就像两个同心衍射体，而不是像洞穴一样的衍射体。