ELECTRICAL EFFECTS GENERATED BY EXPERIMENTAL VOLCANIC EXPLOSIONS

We report on the experimental study of electrical phenomena during exp losive volcanic eruptions, which provides qualitative and quantitative insight into different fragmentation and eruption mechanisms of magma tic melt. The experiments show that air friction and surface enlargeme nt by hydro- and/or aerodynamic magma fragmentation are only minor con tributors to electrical charging of erupted particle clouds in compari son to thermo-hydraulic fracturing of magma by explosive magma/water i nteraction. This process has the potency to explain the frequently obs erved occurrence of Lightning in eruption clouds of explosive volcanic events. (C) 1997 American Institute of Physics.