For as long as he has existed, Man has been fascinated by volcanic eruptions. Of all the natural phenomena, nothing is more mysterious, more grandiose, and more terrifying than an active volcano. Its projections of incandescent matter, its fountains of steam, its rumbles and roars give it a life of its own. No one can remain insensitive to the destructive power of a volcano. Each volcano is unique and often unpredictable. Some have been active for thousands of years; others have remained dormant through the past history of mankind, only to suddenly awaken and erupt without any forewarning. Although volcanoes can kill, they are also a great source of life. More than 400 million of the Earth's inhabitants are able to live thanks to the exceptional fertility of volcanic soil. For more than a century, scientists and volcanologists have been trying to pierce the veil of mystery surrounding volcanoes. They are now able to forecast some eruptions and evacuate the populations threatened by these "Mountains of Fire".