The development of Mt. Vesuvius has been studied since Roman times.  The magma chamber of Vesuvius  lies at a depth of 5-6 km, according to current estimates.  The volcanic activity started about 10,000 years ago.  Periods of frequent eruption alternated with periods of absolute tranquility that sometimes lasted more than 2000 years.  Before the disastrous eruption of 79 AD Vesuvius had been quiet for 1200 years; only a few scientists knew that it was a volcano.  The history of this, the most famous eruption in Europe, is known through a detailed description by Pliny the Younger in two letters to Tacitus.  Since 79 AD Vesuvius has been active at irregular intervals, but has seldom remained quiet very long.  The last major eruption occurred in 1944, but activity may start up at any moment.

   Below: This is a picture that does not do any justice to the beauty that Mother Nature had created on this day.  The rainbow against the mostly clear sky was surreal.  It was awe inspiring in person.  This picture was shot from the top of the hill in Monte di Procida.  What you see from front to back is the town of Bacoli, the gulf of Pozzuoli, the partial rainbow, the city of Pozzuoli (across the water), and Mt. Vesuvius in the background.