A is for (whoever gets Z starts the next theme)

[twyngwyn]

Grows on a tree

A is for Almond

[mytreechange]

F is for Fire

[countessalmirena]

G is for gases spewing upwards and out

[twyngwyn]

H is for Hawaii

[countessalmirena]

I is for ignimbrite (the same thing as ash flow tuff)

[mytreechange]

J is for Jets of steam bursting through the earth

[twyngwyn]

K is for Krakatoa 

[mytreechange]

L is for Lava

[twyngwyn]

M is for Magma

[mytreechange]

N is for Nearby panic

[twyngwyn]

O is for Once is enough!