Figure 4From: The size range of bubbles that produce ash during explosive volcanic eruptionsExamples of ash particles not suitable for the use of stereo-scanning electron microscopy. (a) Vesicle imprints completely filled with finer-grained material; and (b) vesicle imprints oriented perpendicular to the electron beam, both of which inhibit an accurate measurement of vesicle depth (indicated with arrows).Back to article page