Journey into an Icelandic volcano   Dr Freysteinn Sigmundsson, a
geophysicist at the University of Iceland and a co-leader of the
FutureVolc project shows the BBC's Neil Bowdler around the
dormant Thrihnukagigur volcano in Iceland.  They head down into
the volcano on a cradle and see the magma-filled crack where
magma forced its way up through the Earth's crust 5000 years
ago, carving out a unique volcanic chamber.