LABORATORY MODELS OF HAWAIIAN AND STROMBOLIAN ERUPTIONS
LABORATORY MODELS OF HAWAIIAN AND STROMBOLIAN ERUPTIONS
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DOI：
10.1038/331058a0
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发表时间：
1988-01-07
期刊：
影响因子：
64.8
通讯作者：
VERGNIOLLE, S
中科院分区：
文献类型：
--
作者：
JAUPART, C;VERGNIOLLE, S
玄武岩喷发常以活动的周期性变化为特征。在夏威夷，连续喷涌的周期与更长的流出周期交替进行1,2。在斯特隆波利火山喷发中，活动是通过断断续续的离散爆发进行的。我们报告了模拟玄武岩喷发脱气过程的实验室实验。气泡在装满粘性液体的容器底部产生，顶部有一个小的开放导管。气泡上升并积聚在顶部形成泡沫层，泡沫层的厚度增加。当达到临界厚度时，气泡会聚集，泡沫会破裂，产生气泡，其大小取决于液体粘度和表面张力。在低粘度下，形成一个大的气穴，流入导管。它以环形流动的形式喷射，中心射流喷出湿润导管壁的液体膜。在较高的粘度下，会形成许多较小的气穴，这些气穴以段塞的形式上升，并在排气口间歇性地爆发出来。实验表明，在腔室和导管中存在的收缩在决定喷发行为方面起着重要作用。
Basaltic eruptions are often characterized by cyclic changes of activity. At Hawaii, periods of continuous fountaining alternate with much longer periods of effusive outflow1,2. In Strombolian eruptions, activity proceeds through intermittent discrete bursts2–5. We report laboratory experiments that simulate the degassing process in basaltic eruptions. Gas bubbles are generated at the bottom of a tank filled with viscous liquid and topped by a small open conduit. The bubbles rise and accumulate at the roof in a foam layer whose thickness increases. At a critical thickness the bubbles coalesce and the foam collapses, generating gas pockets whose size depends on liquid viscosity and surface tension. At low viscosity a single large gas pocket is formed, which flows into the conduit. This erupts in an annular flow configuration where a central jet expels the liquid films that wet the conduit walls6. At higher viscosity many smaller pockets are formed, which rise as slugs and burst out intermittently at the vent. The experiments imply that the presence of constrictions in the chamber and conduits plays a major role in determining eruption behaviour.