Pyroclastic fall deposit of the 1813 eruption ("Bunka" eruption) at southern region of Suwanose-jima volcano(right). The light grey thickest layer is scoria layer that is produced by the climactic phase of the eruption (sub-plinian style). The underlying layers (dark grey or black) are those by phreatomagmatic and small magmatic eruptions.　

Now I'm very interested in why the styles of volcanic eruptions are diversive. The 1986 eruption at Izu-Oshima volcano, south of Tokyo, Japan, is characterized by diverse types of eruption which produced various types of deposits. This picture (left) is one of the thermal images taken about 3 weeks after the eruption (Okamoto et al., 1987).