The volcanic eruption occurs due to the rapid decompression of the high-pressure high-temperature high-viscosity magma. It is mainly dependent on the appearance of the gas phase in the magma whether it is an explosive eruption or not. In the present study, the volcanic eruption is reproduced with the high-pressure visible shock tube apparatus and simulant materials. The simulant materials for the magma are two-fluid component of silicone oil and acetone. In the experiment, the bubble forming behavior of the simulant materials and the rapid change in pressure was observed. The bubble forming behavior had completed in very short span and then bubbles developed. The number of bubbles nucleated under sudden decompression increased with the decompression rate. It was indicated from the experimental results that the driving force of bubble forming under sudden decompression depends on the decompression rate.

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