Abstract: Northern Hainan Island (Qiongbei) volcanoes are one of the major volcanic clusters in China. A Rn/Th measurement was carried out in April, 2001, in order to get better understanding of the activities of volcanoes and the relevant faults in Qiongbei area. Three traverses were arranged for the measurement. Traverse I for Rn and Th measurement was arranged along the northwest and southeast sides of the Leihuling. The measurement on this traverse focused also on the Leihuling Fault, which is a part of the Rongshan-Lingnan Fault. Traverse Ⅱ for Rn and Th measurement was located on the lip of the Yangnan crater. Traverse Ⅲ for the measurement of gas of earth interior was arranged on both sides of the Leihuling, Maanling and Yangnan craters, respectively. The main purpose of the measurement is to reveal the feature of gas release in crater. The results show that the variations of Rn and Th are closely related to fault structures. The anomalies of Th and Rn observed on traverse Ⅰ and traverse Ⅱ are the distinct reflection of the Rongshan Lingnan Fault. The activity of the fault is analyzed in detail according to the distribution feature and variation of Th and Rn. In addition, the activity of the volcanoes in the studied area is analyzed and discussed as well.

Key words: volcano, fault, Rn and Th measurement, activity

摘要： 琼北火山区是中国的主要火山群之一.笔者应用HDS-1型快速数字闪烁测氡仪对琼北火山群马鞍岭和雷虎岭段的火山及断裂活动性进行了勘测和研究,对荣山-岭南断裂进行了重点测量,查明了该断裂的具体位置,研究了火山及断裂的气体释放特征.发现Rn(氡),Th(钍)的变化与断裂构造有密切关系,在Ⅰ,Ⅱ测线上Th,Rn异常对断裂的反映相当好.根据Th,Rn的展布特征和浓度变化比较深入地分析了断裂的活动性.在雷虎岭西南,荣山-岭南断裂活动性最强,而且,自西北向东南断裂规模及活动性均有增强的趋势.此外,还对火山的活动性进行了讨论和分析.

关键词: 火山, 断裂, Rn,Th测量, 活动性