An examination of the eruption of Mount Pelee on the Caribbean island of Martinique which, on 8 May 1902, incinerated 30,000 people in seconds.
Turkey is in an earthquake zone, as shown only too painfully last year in the city of Izmit.
If the Mamara sea fault moves again, the capital city Istanbul may get just seven seconds warning.
In 1963 the water behind the Vaiont dam in Italy escaped, killing 2,600 people.
Incredibly the dam itself held despite being subjected to a massive force and remains standing today.
Bill McGuire asks whether constructions like the Thames Barrier could prevent flooding elsewhere in the world.
It was constructed after the worst floods in Britain in the 20th century, when the Thames burst its banks in 1953, causing many deaths.