Mount Athos: area - 335.63 square kilometres
Easy, it hasnt :P
Approx. 300 km (straight line).
Mt. St. Helens' May 18th, 1980 eruption changed the landscape drastically and jsut in a few moments at most. The eruption itself was not a typical eruption that would have had a vertical eruptive...
It has only been around for 69 years