Laboratory simulations of sustained volcanic eruptions

Article

关键词: MOUNT-ST-HELENS;    MAGMA DISCHARGE;    COLUMN HEIGHT;    DYNAMICS;    FLOW;    VESUVIUS;    VELOCITY;    BEHAVIOR;    CONDUIT;   

DOI  :  10.1038/41306

来源: SCIE

【 摘 要 】

Many violent eruptions are driven by rapid exsolution of dissolved volatiles within liquid magma. The accelerating two-phase mixture emerges at the vent as a sustained quasi-steady discharge lasting for periods from hours to days (refs 1, 2), The initial growth in discharge rate commonly observed(2-4), subsequent fluctuations(5,6) and discrete pulses and shocks(7) remain largely unexplained, We have simulated volcanic conduit flows by producing sustained, quasi-steady explosions in a liquid undergoing rapid exsolution of a gas. This was done by rapidly decompressing large volumes of CO2-saturated water. The results reveal fluctuations in discharge rate that reflect heterogeneities in the two-phase mixture that form spontaneously as a consequence of the size and geometry of the experimental system, An initial transient with a growing discharge rate is observed in experiments in which material is erupted from a spherical flask up a narrow neck that mimics the magma-chamber/conduit assembly of volcanic systems. The fragmentation region propagates down the neck during the initial transient until it reaches a stable position at the top of the flask, at which point a quasi-steady discharge ensues.

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