Fault location by radon and mercury detection at an active volcano in Nicaragua
Fault location by radon and mercury detection at an active volcano in Nicaragua
复制标题
通过检测尼加拉瓜活火山的氡气和汞进行故障定位
作者：
W. Crenshaw;S. Williams;R. Stoiber
尼加拉瓜的马萨亚火山口复合体和活跃的火山口圣地亚哥（图1）是现今玄武岩火山的所在地。一些束缚火山口并位于火山口内的断层可以在地质学上定位；其他的则是假定的。一个可能更古老的火山口边缘位于现今边缘的南部。为了研究是否可以在这种活火山活动环境中识别断层，在火山口内和附近的232个选定点测定了风化层中氡和汞的浓度。在所研究的已知结构中，超过75%的结构中存在较高浓度的Hg0或Rn或两者。一些迄今被怀疑的结构得到证实，而另一些则没有。缺乏化学特征可能是由于没有构造、不适当的采样地点、断层后熔岩覆盖或构造的其他密封。我们在这里展示了如何使用Rn和Hg0测定在这个活火山的结构分析中有所帮助。
The Masaya Caldera Complex, Nicaragua, with the active crater, Santiago (Fig. 1), is the site of present-day basaltic volcanism1,2. Some of the faults that bound the caldera and lie within it can be located geologically; others are postulated. A possible older caldera rim lies to the south of the present margin. To investigate whether one can identify faults in this environment of active volcanism, concentrations of radon and mercury in the regolith were determined at 232 selected points in and adjacent to the caldera. Higher concentrations of Hg0 or Rn or both occurred over 75% of the known structures studied. Some hitherto suspected structures were confirmed while others were not. Lack of a chemical signature may be ascribed to the absence of a structure, inappropriate sampling sites, post-fault lava cover or other sealing of the structure. We show here how the use of Rn and Hg0 determinations has helped in structural analysis at this active volcano.