In the second photograph we can see an active volcano releasing lava and poisonous gasses into the air. Its eruptions form the so called flows, which are high-temperature clouds of ash and steam that can travel down mountainsides at speeds exceeding that of an airliner. They are very dangerous to the people living in the vicinity of the volcano. It is a well known fact that in the year 79 AD the volcanic eruption of Vesuvius buried the city of Pompeii. At the time of that eruption, the town could have had some 20,000 inhabitants. P.S. Today Vesuvius is not considered the most dangerous volcano in the world. That distinction belongs to Mount Rainier, the highest peak in the Cascade Range in Washington state, USA, which overshadows a population of 2.5 million.