re are the explosive calderas. Formed from the violent explosions of volcanoes, these are large blast craters, usually andesitic in composition. They form from the disintegration of a volcanic summit, following the collapse of the magma chamber after an explosive eruption. (Summerfield p 118). The size of explosive calderas varies but is limited to less than 10 km. (Steinberg p 29-30) The source of these explosions are the differentiation's of the magma chambers lava, over time. As the lava column becomes vertically stratified, the more viscous, gas rich, magma rises to the top. As the pressure is released by initial eruptions, and the level of the magma chamber falls, the pressure is lowered on the magma causing the underlying layers to degas violently. (Summe
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