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Meter‐Scale Experiments on Magma‐Water Interaction
Author(s) -
Sonder Ingo,
Harp Andrew G.,
Graettinger Alison H.,
Moitra Pranabendu,
Valentine Greg A.,
Büttner Ralf,
Zimanowski Bernd
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb015682
Subject(s) - magma , thermite , phreatomagmatic eruption , strombolian eruption , explosive material , groundwater , geology , mechanics , volcano , petrology , materials science , chemistry , geotechnical engineering , seismology , physics , composite material , aluminium , organic chemistry
Interaction of magma with groundwater or surface water can lead to explosive phreatomagmatic eruptions. Questions of this process center on effects of system geometry and length and time scales, and these necessitate experiments at larger scale than previously conducted in order to investigate the thermohydraulic escalation behavior of rapid heat transfer. Previous experimental work either realized melt‐water interaction at similar meter scales, using a thermite‐based magma analog in a confining vessel, or on smaller scale using ≃0.4 kg remelted volcanic rock in an open crucible, with controlled premix and a ≃5 J kinetic energy trigger event. The new setup uses 55 kg melt for interaction, and the timing and location of the magma‐water premix can be controlled on a scale up to 1 m. A trigger mechanism is a falling hammer that drives a plunger into the melt (≃28 J kinetic energy). Results show intense interaction ( L max ≥ 0 . 25m 2 ) at relatively low magma/water mass ratio. A video analysis quantifies rate and amount of melt ejection and compares results with those using the same melt in the smaller scale setup. Experiments show that on the meter scale intense interaction can start spontaneously without an external trigger if the melt column above the initial mixing location is larger than 0.3 m. Experiments suggest that buoyant rise of water domains in a melt column could promote explosive interaction. We assess interaction scenarios between introduced water domains and a magma column, some of which could result in eruptions of Strombolian style, promoting brecciation and incorporation of wall rock debris into a magma column.