Since December 28 2002 the Stromboli Volcano has been particularly active, causing more than once lava flows along its South Eastern slope called the ‘Sciara del Fuoco’ (the volcano is at its peak 3000 m high and approximately 2000 m of its surface is underwater).
The above mentioned slope is covered by loose material of motley dimensions (also made of metric blocks scattered in the sandy bottom matrix). The extreme inclination of the Sciara del Fuoco slope is the result of a major land slide event that occurred about 5000 years ago, following which the side of the volcanic cone was destroyed, leaving a significantly steep slope characterized by a critical incline particularly vulnerable to conditions of gravitational instability by the loose material it is made of. Therefore the triggering of land slides or land movement ranges from daily small slips of sandy material to the rolling of metric blocks up to potentially catastrophic events of major entity.
Conditions for the triggering of land slide phenomena are linked to the presence and scale of volcanic activity and in particular to the swelling of the volcanic edifice which may cause a sudden increase of the slope’s inclination level along the Sciara del Fuoco (i.e. consequent landslide phenomena), which can occur as quickly as in ten minutes particularly following powerful explosions or even slowly but progressively ( during charging phases of the deep magmatic system). Furthermore the critical stability conditions of the slope may degenerate as a result of an ongoing lava flow, which significantly increases the slope’s inclination and load.
In fact on December 30 2002, due to the critical volcanic activity of those days and the associated ongoing lava flow, a part of the Sciara del Fuoco collapsed causing a landslide of18 million cubic meters of material. From the seismic wave recordings the detachment of the wall occurred in two separate close phases, in fact the landslide was first triggered in the submerged part of the Sciara and then spread to the surface part.
The underwater landslide generated a sequence of tsunami waves that in a very short time interested the whole island of Stromboli, the Northern part of the Island of Panarea and eventually spread to the other Islands of the Eolian Archipelago, along the Messina and Calabria coasts.
The maximum height reached by the tsunami wave on the coast, reported during the monitoring phase, reached peaks above 10m in many parts of the Island of Stromboli.
The tsunami hit the Northern part of the Island with greater force than the Southern one. Fortunately since the event occurred during the winter season with low tourist affluence, no deaths or injuries were reported after the tsunami.
The tsunami however did cause serious damage to the island’s population particularly to the homes, the tourist facilities mostly located in the coastal area.
In fact immediately following the event, the National Fire Department (VVF) teams scouted the locations for damage assessment and relative operations needed to ensure the safety of those buildings most affected by the tsunami and restoration of the island’s road system..
Immediately after the onset of the anomalous events the National System of Civil Protection started to mobilize all available and necessary resources to face the emergency in progress. In particular the Operational Centers of Stromboli(COA-Advanced Operational Centre) and Lipari were set up and all the population that wanted to evacuate the island was transferred to the other islands of the Archipelago on the Sicilian coast and monitoring networks were installed and/or strengthened.
Following the 30 December 2002 events, the National System of Civil protection deemed necessary to convene its scientific consultation body (Commissione Nazionale Grandi Rischi) (National Major Risks Commission) to assess the potential development of the scenario in progress.
The landslide event and the tsunami just occurred had been the direct consequence of a rapid and anomalous evolution of the persistent volcanic activity of the Stromboli. Significant and constant topographic deformations to the volcanic edifice were being regularly reported during those days.
The Commissione Grandi Rischi –Major Risk Commission- analysed the situation and assessed that the total evacuation of the population from the island was not necessary, and beside strengthening the monitoring network decided on the importance of an appropriate information campaign to the population on the events in course and risks including the best behaviour to adopt in case of sudden aggravation of the scenario. These measures allowed the resident population of the Island to return to their homes and in short to ensure the recovery of normal tourist business.
Following the emergency events of 2002-2003 several monitoring networks have been installed on the volcano, and particularly against the risk of tsunamis the following instruments were installed:
For the monitoring of the Sciara del Fuoco surfacing slope and potential landslide phenomena capable of triggering tsunami waves, an interferometer synthetic aperture radar (SAR) was installed , a widely experimented system for monitoring landslides, placed on a volcano for the first time.
SAR allows to collect information on the state of deformation of the volcanic edifice, both in day light and at night, also under adverse conditions, as those typical of volcanic environments (ashes, dust, gas clouds).
The system captures an image of the radiated area every 12 minutes, and connected partly in wireless and partly in optic fiber transmits the acquired data, roughly 120 images daily, tothe Advanced Operational Centre (COA) of Stromboli and to the Central Functional Center for Volcanic Risk of Rome
This instrument can also be used to monitor environment and marine parameters (conductivity dissolved oxygen, ph, turbidity, etc.).
The system has been researched to work in complete autonomy with a data transmission in real time through radio waves to the Advanced Operational Center of Stromboli.
In order to monitor the stability of the Sciara del Fuoco submerged slope an elastic beacon instrumented with a wavemeter and hydroacustic monitoring system off the Stromboli Island shore.
The beac on is a wavemeter buoy anchored at 200 m from the coast on a 43 m deep bed by a dead body weighing approximately 10 tons, connected with the structure by a steel cable.
COA - Centro Operativo Avanzato
During the emergency of 2002-2003, the Department of Civil Protection implemented a permanent COA-Advanced Operational Center in Stromboli located in the higher part of the town of Stromboli , behind the Church of San Vincenzo.
COA is a Civil Protection integrated structure which in case of emergency is ready to welcome DPC staff from the various operational structures and scientific community. Although the presence of staff is planned according to actual need, the structure is operational on a permanent basis on the Island, in constant contact with the Department of Civil Protection and is ready to make decisions in real time in the field of volcanic risk mitigation. The COA collects all the signals and data coming from the monitoring instruments coordinated by the Civil protection as well as the INGV (National Institute of Geophysics and Volcanology) monitoring network and other research institutions.
Early Warning System
A system of sirens to alert the population has been activated on the coastal area and appropriate signs have been installed indicating to the population and to the tourists the evacuation routes to the safe areas in case of emergency.
Pier in Ginostra
In the village of Ginostra, in order to ensure a safe and quick evacuation of the population in case of emergency, a pier was built to serve as docking port connecting to the other islands and to the main land.
Radio communication network
Following the 2002 emergency a synchronous radio network was activated to guarantee full coverage of the archipelago and of the Thyrrhenian side of the coasts of Messina and the regions of Calabria, Lucania and Campania including the Policastro Gulf coastal area and with SSI (the Italian Situation Room) and the Central Operational Headquarters of the Department of Civil Protection in Rome in order to coordinate the potential emergencies in that area.
The Island of Stromboli is an active volcano, whose persistent activity referred to as “stromboliana” presents moderate explosive activity of mid intensity occurring every 10 to 20 minutes, and specifically for this reason is increasingly becoming a coveted tourist destination.
The island’s economy in fact is mainly based on tourism, linked to the presence of its spectacular volcano.
The island’s powerful volcanic activity has not however discouraged the ever growing tourist flow, on the contrary, following the earliest phases of major emergencies tourists have flocked to the Island to witness the spectacular volcanic explosions.
Therefore, in order to manage the delicate balance between the need from the economic point of view to allow a constant influx of tourists and the need at the same time to manage the risks determined by the tourists presence on the Island, Stromboli has come up with:
- A very useful handbook supplying all the necessary information to visit the Island safely, including information on the local civil protection system and behavior code to adopt in emergency situations
- Safety guide for hiking trails
Stromboli: A neither good nor bad Volcano (link to the video)
The video is a filmed documentary related to the interventions put in practice by Civil Protection, on the Stromboli Island, following the extraordinary volcanic activity, started in December 2002 and about the linked events that followed as, the seaquake occurred on December 30th, 2002.