Eighteen-year-old Nicanor Mabao was one of the three who survived what scientists call a phreatic, or steam-driven, explosion.

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Furthermore, it would take a combination of extreme events to make things dangerous in Tokyo (nuclear re-criticality, steam explosion) etc all of which are being rendered less and less likely as time passes and the heat decay process progresses.

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Institute Director Renato Solidum said the explosion early Tuesday was "steam-driven" and is considered "normal" activity for a volatile volcano like Mount Mayon.

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