Vapor Bubbles and Velocity Control on the Cooling Rates of Lava and Pyroclasts During Submarine Eruptions

Moitra, P.; Sonder, Ingo

doi:10.1029/2022jb024665

Cited by 2 publications

(1 citation statement)

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“…As mentioned in Section 2.1.1, we use spherical-shaped samples for reproducible results and quantification of heat transfer parameters. More research is necessary to quantify the geometric dependency in order to investigate its importance relative to the many other factors relevant to magma-water interaction, such as the magma's own motion and deformation, external water flow (Moitra and Sonder, 2022), water salinity, and pressure (Gregg, 2013;Wohletz et al, 2013;Zimanowski et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Experimental constraints on the stability and oscillation of water vapor film—a precursor for phreatomagmatic and explosive submarine eruptions

Sonder

Moitra

2022

Front. Earth Sci.

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Pre-mixing of magma and external water plays a key role in driving explosive phreatomagmatic and submarine volcanic eruptions. A thin film of water vapor forms at the magma–water interface as soon as hot magma comes in direct contact with the cold water (Leidenfrost effect). The presence of a stable vapor film drives efficient mixing and mingling between magma and water, as well as magma and wet and water-saturated sediments. Such mixing occurs before explosive molten fuel–coolant type interactions. Using high-temperature laboratory experiments, we investigate the effect of magma and water temperatures on the stability of vapor film, which has not been performed systematically for a magmatic heat source. The experiments were performed with re-melted volcanic rock material, from which spherically-shaped rock samples were produced. These samples were heated to 1,110°C and then submerged in a water pool with a constant temperature (3–93°C). The experiments were recorded on video, and, synchronously, sample and water temperatures were measured using thermocouples. The time-dependent thickness of the vapor film was measured from the video material. The vapor film tends to oscillate with time on the order of 102 Hz. We find that the vertical collapse rates of vapor films along the sample–water interfaces are 13.7 mm s−1 and 4.2 mm s−1 for water temperatures of 3.0°C and 65°C, respectively. For a given initial sample temperature, the thickness and stability time scales decrease with decreasing water temperature, which has implications for the efficiency of pre-mixing required for explosive eruptions. Using thermodynamics and previously measured material parameters, it is shown that a sudden collapse of the vapor film can start brittle fragmentation of the melt and thus serves as the starting point of thermohydraulic explosions.

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Section: Discussionmentioning

confidence: 99%