Fig. 3From: Physical characteristics of scoriae and ash from 2014–2015 eruption of Aso Volcano, JapanThin section images of a scoria and ash. a Open nicol image of a typical high-porosity scoria (Fig. 2a). b Open nicol image of the molten scoria shown in Fig. 4f. c Ash observed by a microscope showing the existence of fine ash \(<63 \, \upmu \hbox {m}\). d Magnified view of (c)Back to article page