What to know - Vesuvius

The most likely type of eruption of the Vesuvius is an explosive eruption of medium-low energy. However, as a safety measure, the National Civil Protection Planning refers to a medium energy eruption as a scenario, which includes:    

• the formation of an eruptive column made of gas, burning lava clots, and several kilometres high ashes.    

• the fall of volcanic material, both large (like volcano bombs and blocks) in the area closest to the eruptive vent and smaller particles (like ashes and lapilli) that are blown by the wind, can settle even several tens of kilometres away.    

• the flow of pyroclastic flows, which are avalanches of gas, ash, and volcanic fragments at elevated temperatures and speed for several kilometres down the slopes of the volcano.    

Seismic activity may occur before the eruption and accompany its different stages, resulting in particularly severe damage to buildings already hit by falling ash and lapilli.

On Vesuvius, a volcanic monitoring system of geophysical and geochemical parameters (seismicity, ground deformation, gas composition, and temperature, etc.) whose changes may be forerunners of an eruption, is active.
Monitoring is crucial for defining the state of volcanic activity and the related warning level and implementing measures outlined in the Civil Protection Plan.
Vesuvius monitoring data are reported by the Ingv - Vesuvius Observatory to the Department of Civil Protection and published on the website of the Vesuvius Observatory.  

The warning system has specific "alert levels" that indicate the state of the volcano based on monitoring parameters and possible ongoing phenomena. The green alert level represents ordinary volcanic activity, while the yellow, orange, and red alert levels correspond to increasing stages of volcanic instability leading to a possible eruption. The length of each alert level can be highly variable.
The Department of Civil Protection declares alert levels in liaison with the Civil Protection of the Campania Region. Any variation in alert level is assessed according to the information provided by INGV's Vesuvius Observatory upon advice from the National Commission for the Forecasting and Prevention of Major Risks.
The following actions to be taken by the National Civil Protection Service are set out in the operational phases (attention, pre-alarm, and alarm) foreseen in civil protection planning. The Prime Minister declares the pre-alarm and alarm phases.  

Currently, the alert level for Vesuvius is basic (i.e. green).  

The red zone covers the area exposed to the possible invasion of pyroclastic flows, which, due to their elevated temperatures and speed, are the most dangerous phenomenon for people, and an area subject to elevated risk of collapse of building roofs due to the accumulation of pyroclastic deposits, such as volcanic ash and lapilli. The red zone includes 25 municipalities in the provinces of Naples and Salerno: Boscoreale, Boscotrecase, Cercola, Ercolano, Massa di Somma, Ottaviano, Pollena Trocchia, Pompeii, Portici, Sant'Anastasia, San Giorgio a Cremano, San Sebastiano al Vesuvio, San Giuseppe Vesuviano, Somma Vesuviana, Terzigno, Torre Annunziata, Torre del Greco, Trecase, Palma Campania, Poggiomarino, San Gennaro Vesuviano, and Scafati, and only partially the districts of Barra, Ponticelli and San Giovanni a Teduccio in the municipality of Naples, the municipality of Nola and the enclave of Pomigliano d'Arco in the municipality of Sant'Anastasia.  The yellow zone, outside the red zone, covers the area exposed to the significant fallout of volcanic ash and pyroclastic materials, the accumulation of which could damage some buildings. The yellow zone includes 63 municipalities and three districts of the City of Naples.  

The only safeguard measure for the red zone is population evacuation before the eruption.
People can decide whether to autonomously find accommodation outside the risk zones or benefit from the accommodation offered by the state in the Region or Autonomous Province twinned with their municipality.
In the yellow zone, the evacuation of people will be considered during the event, depending on the direction of the winds and the extent of the eruption.
The Plan for volcanic risk for Vesuvius is national, meaning it has been drafted by the entire National Civil Protection Service starting with the Civil Protection Department, Campania Region, Naples Prefecture, municipalities in the red zone, and twinned Regions and Autonomous Provinces.

In the pre-alarm phase, people who want to evacuate can do so autonomously, moving to an alternative accommodation (i.e., second home, from relatives or friends, rented house) by getting a financial contribution from the State.
In the alarm phase, people can decide whether to evacuate by means provided by the State or autonomously. In the latter case, the evacuation must be reported to the municipality, and the routes provided in the planning must be followed according to the established schedules.
The population can also decide whether to move to an alternative self-chosen accommodation with a financial contribution from the State or take advantage of the accommodation offered in the twinned Region or Autonomous Province.
Those who decide to evacuate with the means made available by the State must reach the waiting area identified by the Civil Protection Plan of the municipality, either autonomously or with the shuttles organized by their municipality. From there, the transfer to the meeting area outside the red zone will occur with the means made available by the Campania Region. In contrast, the transfer to the twinned Region or Autonomous Province will be guaranteed by the means of transport identified by the planning (train, bus, ship).
The Plans of the individual Regions and Autonomous Provinces outline the relocation and hosting of the population.  

The IT-alert public warning system for volcanic risk at Vesuvius is used to give early warning of a potential upcoming eruption with the resulting need to take civil protection actions, including the evacuation of the population living in the red zone, provided for in the plans. When the operational phase of "alarm" is activated, an IT-alert message is sent to the cell phones of those in the Campania region to inform them of the potential danger. It is, therefore, essential to know what to do right away.