Explosive properties of water in volcanic and hydrothermal systems
Explosive properties of water in volcanic and hydrothermal systems
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DOI：
10.1029/2008jb005742
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发表时间：
2009-05-23
影响因子：
3.9
通讯作者：
Mercury, L.
中科院分区：
文献类型：
--
作者：
Thiery, R.;Mercury, L.
本文从热力学的观点出发，论述了水作为炸药的物理化学条件。这种现象经常发生在热液和火山系统中，当水从其初始平衡状态被粗暴地转移时。水（液体或气体）变得亚稳态或不稳定，并通过液-气混合物的剧烈分层而重新平衡。在第一步中，亚稳态的唯象方法是在一个组件的角度来看，介绍了亚稳域的范围内的亚稳域的亚稳域的概念和划定。物理机制（气泡成核，空化，spinodal分解），这是在这些爆炸性的水的转变，涉及到什么是详细的自然喷发的主题。利用文献瓦格纳和Pruss状态方程给出了亚稳水的热力学性质（P-v-T-H-U）。然后，所产生的不同可能的物理转换，包括减压，蒸发，等压加热，和出溶，参与水爆炸的机械功进行了量化。推广了经典的可逆假设下的能量平衡计算，提出了一种考虑不可逆性的途径。该模型可用于根据基于爆炸能量的标度律估计火山影响的大小。
This paper describes, from a thermodynamic point of view, the physicochemical conditions, under which water behaves as an explosive. This phenomenon occurs frequently in hydrothermal and volcanic systems when water is brutally shifted from its initial equilibrium state. Water (either liquid or gas) becomes metastable or unstable and reequilibrates by violent demixing of a liquid-gas mixture. In a first step, a phenomenological approach of metastability is given in a one-component perspective, introducing the notion of spinodals and delimiting the extent of metastable fields. The physical mechanisms (bubble nucleation, cavitation, spinodal decomposition), which are involved in these explosive transformations of water, are detailed in what relates to the natural eruption topic. The specific thermodynamic properties (P-v-T-H-U) of metastable water are presented by using the reference Wagner and Pruss equation of state. Then, the mechanical work produced by the different possible physical transformations, including decompression, vaporization, isobaric heating, and exsolution, involved in water explosions are quantified. The classic calculation of the energy balance under the reversible assumption is extended, proposing a pathway to take irreversibility into account. This model can be used to estimate magnitude of volcanic impacts from scaling laws based on explosion energies.