Lava
lakes are large volumes of molten
lava, usually
basaltic, contained in a
vent, crater, or broad depression. Scientists use the term to
describe both lava lakes that are molten and those that are partly
or completely solidified. Lava lakes can form (1) from one or more
vents
in a crater that erupts enough lava to partially fill the crater;
(2) when lava pours into a crater or broad depression and
partially fills the crater; and (3) atop a new vent that erupts
lava continuously for a period of several weeks or more and slowly
builds a crater higher and higher above the surrounding ground.