Sawtooth wave-like pressure changes in a syrup eruption experiment: implications for periodic and nonperiodic volcanic oscillations
Sawtooth wave-like pressure changes in a syrup eruption experiment: implications for periodic and nonperiodic volcanic oscillations
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糖浆喷发实验中的锯齿波状压力变化：对周期性和非周期性火山振荡的影响
DOI：
10.1007/s00445-018-1227-z
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
and M. Ichihara
中科院分区：
文献类型：
--
作者：
Kanno;Y.;and M. Ichihara
这项研究是基于观察的连续波的压力变化（STW），在重复的气体排放过程中观察到的糖浆喷发实验。在许多活火山观测到类似的波形作为大地测量信号。通过研究此类实验的物理学，我们经常发现适用于自然火山现象的新想法和见解。因此，我们尝试识别我们的实验系统和自然火山系统的共同特征。我们推断，在我们的实验中的振荡机制是类似的流动诱导振荡之间的耦合控制的弹性电容和可变的流动阻力。我们开发了一个基本的管道室系统，以定量地测试这一假设。我们观察到三种不同的振荡模式：周期性STW，非STW和非周期性STW。建立了一个数学模型来支持这一假设，并与现有的火山系统模型进行比较。流动引起的火山振荡模型在数学上类似于我们的实验系统中得出的模型。我们的研究结果表明，流动模式的转变是必不可少的振荡行为在气体排放。一个重要的发现是，循环的周期性和波动性受到管道内向上和向下流动之间的相互作用的控制，特别是在气体排放终止和向下一个循环的过渡期间。类似的相互作用发生在自然火山：在爆炸性喷发结束时，喷出物质的回落或回流可能会调节下一个喷发周期的爆炸性和周期性。我们的实验系统可以为理解天然火山系统的振荡行为提供一个有用的工具。这项研究也可能证明，原始喷发实验提供了一个有用的工具，用于解释自然火山系统的振荡和喷发行为的动力学在教育（例如，开放日）示威。
This study is based on the observation of sawtooth wave-like pressure changes (STW) observed during repetitive gas emissions in a syrup eruption experiment. Similar waveforms are observed at many active volcanoes as geodetic signals. By studying the physics of such experiments, we often find new ideas and insights that are applicable to natural volcanic phenomena. We consequently try identifying the features common to both our experimental system and natural volcanic systems. We infer that the oscillatory mechanism in our experiment is similar to flow-induced oscillation controlled by a coupling between elastic capacitance and variable flow resistance. We developed an elementary pipe–chamber system to quantitatively test this hypothesis. We observed three distinct oscillatory patterns: periodic STW, non-STW, and nonperiodic STW. A mathematical model is constructed to support the hypothesis and to enable comparison with existing models of volcanic systems. Models of flow-induced volcanic oscillations are mathematically similar to the model derived from our experimental system. Our results indicate that flow pattern transitions are essential for oscillatory behavior during gas emission. An important finding is that cycle periodicity and fluctuation are controlled by interactions between upward and downward flow within the pipe, especially during the termination of gas emission and the transition to the next cycle. Similar interactions occur in natural volcanoes: during the termination of an explosive eruption, fall-back or drain-back of ejected materials may modulate the explosivity and periodicity of the next eruption cycle. Our experimental system may provide a useful tool for understanding the oscillatory behavior of natural volcanic systems. This study may also give a proof that the original eruption experiment provides a useful tool for explaining the dynamics of oscillatory and eruptive behaviors of natural volcanic systems in educational (e.g., Open Day) demonstrations.