Lava pillar animation
This animation shows an interpretation of the sequence of events during the drainback phase of a submarine volcanic eruption. The movie shows how the rhythmic formation of vapor cavities and lava crusts form the thin, closely spaced, horizontal "lava shelves" on the sides of a lava pillars. The view is a cross-section through a lava flow, including one side of a lava pillar (the hollow interior of the pillaris along the left edge). Red is molten lava, black is solid lava crust, dark blue is cold seawater, and light blue is hot vaporized seawater.
A description of the sequence of events in the animation:
(1) The movie starts after the flow is fully inflated. The lava flow has a solid upper crust and a molten interior. The lava pillar is a hollow pipe connecting the upper and lower crusts of the flow, allowing seawater trapped beneath the flow to escape upwards.
(2) As lava drainback begins, small cavities form under the upper lava crust, and seawater is immediately syringed into these cavities through the crust above. When the seawater encounters the molten lava a hot vapor phase forms, allowing residual lava to drip down from the underside of the upper crust.
(3) The upper crust eventually fails where it is unsupported from below, condensing the vapor and exposing the molten lava to cold seawater. A new crust starts to form on the subsiding lava which attaches to the side of the pillar.
(4) As drainback continues the new lava crust becomes stranded and a new vapor cavity forms, this time only near the pillar because the crust stays in contact with the lava surface away from the pillar.
(5) The perched crust also eventually fails creating a lava shelf with quenched lava drips on its underside. This process repeats over and over until drainback ends.
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