[4] Inside the crater, forests thrived along with three lakes from which pasturing herds drank from, however they would ultimately disappear due to rising temperatures as Vesuvius began its erupting process.

[4][5] As early as August 1631, visible signs of Vesuvius' reawakening could be seen on the North flank of the Vesuvian cone, where sightings of increased fumarolic activity and nocturnal incandescence were reported.

[7] Several unusual phenomena preceded the eruption, including acoustic disturbances, ground deformations, gas emissions, and changes in groundwater.

Local vegetation showed signs of distress, with drooping plants and reports of animal disappearances, likely due to the emission of toxic volcanic gases.

Wells and springs began to produce muddy water, with some sources turning saline, indicating a disturbance in the underlying hydrogeological system.

[8] The eruption began on 16 December 1631, with the opening of a fissure vent on the western side of Vesuvius, close to the base of the volcanic cone.

[9] The explosion caused a giant eruption column, which pushed by high pressure inside the volcano reached about 13 km altitude.

According to William Hamilton "Giulio Cesare Braccini measured with a quadrant the elevation of the mass of clouds that was formed over Vesuvius during the eruption, and found it to exceed thirty miles in height".

This gap in the plate enables upwelling convection currents to interact with enriched mantle materials from the subducted slab, resulting in Vesuvius' distinct volcanic characteristics compared to the other volcanoes in the Campanian arc.

Arc-related magmatism also played a significant role in the lithospheric detachment, with the interaction of convection currents and varying subduction dynamics believed to have driven the slab tear.

Pyroclastic flows were a significant component of the 1631 eruption, depositing thick, poorly sorted layers in the proximal areas.

Surge deposits, found in localized areas, consist of well-sorted ash and pumice, indicating turbulent flow conditions.

[9] It is estimated that around 4,000 people were killed by the eruption, making it the highest death toll for a volcanic disaster in the Mediterranean in the last 1800 years.

[9] Pyroclastic flows, ash falls, and toxic gases caused a majority of the deaths in nearby villages, including Torre del Greco, as many people ended up being suffocated or buried under debris.

[18] Many buildings were also weakened by seismic activity occurring throughout the eruption process, and eventually collapsed under the weight of accumulated ash or were wiped out by succeeding lava flows.

Ash falls contributed to the destruction of farmlands, killing plant life and causing land infertility on a large scale.

[19] Due to the proximity of Vesuvius to Naples, this eruption was broadly described by contemporary authors and its study affected the evolution of natural philosophy in the first half of the 17th century.

During this time period, many people believed that a volcano erupted because the Gods were attempting to punish humans for their failure to adhere to proper morals.

Although the population in the region was predominantly Roman Catholic at this time period, so they believed their singular god was punishing the town for its collective decadence and immorality.

The initiative to understand volcanic events grew out of a need to limit damages and loss of life in the future(which was highlighted by the 1631 eruption).

Thus, the purpose of the observatory was both to predict and prepare for dangerous eruptions and to enhance the common understanding of volcanology in the modern age.

[26] The observatory was placed on the southern slope of Mount Vesuvius (far from the crater to stay out of danger), in a Campanian town called Herculaneum.

[11] While it is not possible to predict the exact timing of the eruption, the Italian government and the INGV are continuously monitoring the volcano to be aware of a potential volcanic event.