On May 27, 2008, a strong earthquake of magnitude 5.3 Richter hit Zanjan province. The radon concentration has been measured and registered at the time of earthquake occurrence at 10:48 local time inside the Katalekhor cave being situated at suburb of Zanjan city. After this event, it was planned to measure and analyze the radon concentration in the same year (2008) and 10 years after the earthquake (2018) by using passive methods and the results have been presented. Real time observations show an increase of five times in radon concentration when earthquake happened comparing to normal condition.

中文翻译：

---

与 10 年的后续数据相比，地震期间 Katalekhor 旅游洞穴中氡浓度增加

2008 年 5 月 27 日，里氏 5.3 级强烈地震袭击了赞詹省。在位于赞詹市郊区的 Katalekhor 洞穴内的氡浓度已在当地时间 10 点 48 分发生地震时进行测量和记录。此次事件后，计划采用被动方法测量和分析同年（2008年）和震后10年（2018年）的氡浓度，并给出了结果。实时观测显示，与正常情况相比，地震发生时氡浓度增加了 5 倍。