Pompeii: The New Dig

PROFESSOR CHRIS JACKSON: 24 hours before the eruption, things would have started to change in Pompeii.

VOLCANO RUMBLES SOFTLY CHRIS: There would have been a series of earthquakes shaking the city.

RUMBLING GROWS CHRIS: There would be smells in the air, sulfur dioxide being expelled from the magma within the volcano.

There would have been emissions of steam out of the volcano as magma rose through the volcano and actually came into contact with water.

Animals, birds would have started to leave the area.

They would have known something had changed.

And then about an hour before the eruption, there was an emission of steam and ash from Vesuvius.

Gases within the magma had started to increase the pressure within the volcano, which at that time didn't have a crater but was covered by hard rock.

Those pressures built and built and built, finally blowing the top off the volcano.

EXPLOSION ROARS CHRIS: Magma and rocks surged out of the center of that crater, going up a few tens of kilometers very quickly into the atmosphere.

The people living in Pompeii at that moment would have known something was happening, but they wouldn't have heard anything straight away, and that's because the sound of the top of the volcano being blown off took 24 seconds to reach them.

VOLCANO EXPLODES LOUDLY: