Formation of lauoho o Pele (Pele’s hair) by extreme stretching of bubbly magma

Abstract Lauoho o Pele (often called Pele’s hair) is a common product of basaltic volcanism, produced during Hawaiian lava fountaining, gas jetting, and on the surface of flowing lava. The morphology—long thin strands of glass—indicates that these strands are formed through stretching of filaments of melt. The prevailing model is that they are formed by the action of jets of volcanic gas that “spin out” threads of melt, which quench as hairs. However, this mechanism does not explain the formation of lauoho o Pele on lava flows and lava lakes, or the occurrence of “hanks” of lauoho o Pele—bundles of hundreds to thousands of near-identical aligned strands. We propose and test an alternative mechanism: that lauoho o Pele can be formed by the extreme stretching of parcels of bubbly magma. We created pucks of synthetic bubbly magma using techniques derived from artistic hot-glass working, which we then stretched mechanically. This process produces bundles of filaments, similar to lauoho o Pele, via the stretching of the plateau borders where three bubbles meet; the number of filaments is determined by the abundance of bubbles in the molten glass. We find that lauoho o Pele forms at high vesicularity in our experiments, which is consistent with the interiors of high Hawaiian lava fountains, and the surfaces of lava lakes, and proximal and intubated lava flows.