Abstract

One of the main natural disasters is explosive volcanic eruptions, often lasting 2–4 months. It is obvious that such eruptions of volcanoes cause simultaneous mass release of gas bubbles from the melts of their shallow peripheral chambers, which must lead to a sharp increase in the volume of material contained in them, i.e., to explosions. It is shown that the main prerequisite for an explosive eruption is a sharp decrease in the solubility of water in melts known from experimental data at pressures less than 1 kbar corresponding to a depth of 3.5 km (Shilobreeva et al., 1991). Therefore, rising water-saturated melts characteristic of suprasubduction (convergent) settings, automatically become supersaturated with water when they reach depths of 3–4 km, and are thus an explosive mixture that is ready to blow up at any moment. However, the release of gas bubble nuclei is a very energy-consuming process, and will not begin by itself. We believe that the trigger for a catastrophic explosion can be one of the earthquakes preceding the eruption, which resonates with self-oscillations in the peripheral chamber beneath the volcano. This greatly increases the power of the impulse and helps to overcome the energy barrier. It is shown that the necessary and sufficient conditions for the occurrence of a catastrophic eruption are: 1) the existence of a shallow chamber with a water-supersaturated magma melt; the presence of other volatiles (CO₂, SO₃ etc.) does not play a significant role here; 2) the occurrence of a triggering earthquake that is in resonance with self-oscillations in this chamber; and 3) the presence of a continuous supply of the peripheral chamber beneath the active volcano with new melt portions, thus prolonging the eruption.

中文翻译：

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灾难性火山爆发：成因与机制

摘要

主要的自然灾害之一是爆炸性火山爆发，通常持续2-4个月。显然，火山的这种喷发导致气泡同时从其浅层外围腔室的熔体中大量释放出来，这必须导致其中所含材料的体积急剧增加，即导致爆炸。结果表明，爆发性喷发的主要前提条件是，在小于1 kbar的压力（相当于3.5 km的深度）下，根据实验数据可知，水在熔体中的溶解度急剧下降（Shilobreeva等，1991）。因此，超俯冲（收敛）环境中上升的水饱和熔体特性会在达到3-4 km的深度时自动变为水过饱和，因此是随时可能爆炸的爆炸性混合物。然而，气泡核的释放是一个非常耗能的过程，它本身不会开始。我们认为，灾难性爆炸的诱因可能是喷发前的地震之一，它与火山下方外围室内的自激振荡产生共鸣。这大大增加了脉冲的功率并有助于克服能量屏障。结果表明，发生灾难性喷发的必要和充分条件是：1）存在一个浅水室，其水溶质岩浆熔体过饱和；其他挥发物的存在（CO 会在火山下面的外围腔室中与自激振荡产生共振。这大大增加了脉冲的功率并有助于克服能量屏障。结果表明，发生灾难性喷发的必要条件和充分条件是：1）存在一个浅水室，其水饱和岩浆融化。其他挥发物的存在（CO 会在火山下面的外围腔室中与自激振荡产生共振。这大大增加了脉冲的功率并有助于克服能量屏障。结果表明，发生灾难性喷发的必要条件和充分条件是：1）存在一个浅水室，其水饱和岩浆融化。其他挥发物的存在（CO₂，SO ₃等）在这里不起作用；2）在该室内发生与自身振荡共振的触发地震；3）在活动火山下方不断向外围火山室供应新的熔体部分，从而延长了喷发时间。