THE 1631 ERUPTION

The 1631 eruption, with more than 4,000 victims, was the most violent and destructive event on Vesuvius in recent times. It happened after almost five centuries of quiescence, during which time the volcano had been in a closed conduit state.

S. Gennaro stops the 1631 eruption (N. Perrey - 1631)

Before this eruption there had been macroscopic precursory phenomena such as earthquakes and ground deformation; it started at 7a.m. of 16th December following the opening of a fracture on the south-west slopes of the volcano. An eruption column formed, reaching a height of 13-19 km. This was immediately followed by the fall of blocks and lapilli in the areas to the east and north-east of the volcano, until 6p.m. of the same day.

During the night of 16th and 17th December there followed a succession of significant explosions with ash fallout, accompanied by heavy storms. At 10a.m. of 17th December several pyroclastic currents were observed running down the sides of the volcano, destroying the villages on its slopes. These pyroclastic currents reached the sea at Torre del Greco and Torre Annunziata.
During the night between the 16th and 17th of December and on the afternoon of the 17th the formation of lahars took place and the intense rainfall caused rapid mudflows, both along the slopes of the volcano and in the plains to the north and north-east.
The eruption lasted only 48 hours and the explosive phases, responsible for the formation of pyroclastic flow and surge deposits, caused the partial destruction of the cone of Vesuvius, bringing its height down by over 450 m.

The 1631 eruption (Claude Lorrain)

The 1631 eruption is considered by volcanologists to be an example of the worse case scenario if eruptive activity were to recur. The Civil Protection Corps' current emergency plan has been conceived with the aim of planning the measures to be taken to protect the population from the consequences of an eruption of similar intensity to the 1631 eruption.