VOLCANIC ERUPTIONS - Natural Disaster Profile - Technical Hazard Sheet
The different types of ("primary") eruptive events are:
- Pyroclastic explosions;
- Hot ash releases;
- Lava flows;
- Gas emissions;
- Glowing avalanches (gas and ash releases).
Secondary events are
- Melting ice, snow and rain accompanying eruptions are likely to provoke floods and hot mudflows (or lahars);
- Hot ash releases can start fires.
Factors of Vulnerability
- Topographic factors;
- The proximity of a population to the volcano;
- Structures with roof not resistant to ashes accumulations;
- The lack of warning system and evacuation plans.
Main causes of Mortality and Morbidity
The risk depends on the different types of event:
- Mediated trauma, crush type injuries, and lacerations can be caused by explosion and contact with volcanic mass;
- Hot ash, gases, rock and magma cause skin and lung burns, asphyxiation, conjunctivitis or corneal abrasion;
- Breathing the gases and fumes can cause acute respiratory distress;
- Acid rain provokes eyes and skin irritation.
In the case of ashfall, particularly in fine particles, bronchial asthma and other chronic respiratory conditions can be aggravated in children as well as in adults. Death is highly improbable. Nonetheless, it can occur in persons with serious symptoms if they do not protect themselves from the ashes.
Ashes can have toxic consequences (i.e. gastrointestinal problem) due to ingestion of contaminated food or water.
Ashes can have mechanical consequences. The weight of ash may cause collapse of building (i.e. trauma).
Damage on health infrastructures and water systems can be severe. Problem of communication (ashes create serious interference) and transportation (poor visibility and slippery roads) are likely to happen.
Pending an assessment, needs can be anticipated such as: search and rescue, medical assistance, managing population displacement in the short-term, reducing the risk for vulnerable groups of being exposed to ashes, raising awareness on the risk associated with ashes (health and mechanical risk) and maintaining food security conditions over the long term (lava, ashes and acid rain cause damage to crops and livestock).
Volcanic eruption have an important potential lethal impact in the absence of mitigation measures.
- Long-term management of economic and urban development of areas surrounding active volcanoes;
- Preparedness plans and early warning systems (volcanological /seismological);
- Public awareness and education on the risks and contingency plans;
- Full or partial evacuation of the population;
- Masks that retain small particles of ash for those who need to work in an ash-contaminated environment and for vulnerable groups (children, old people, those who have respiratory problems (asthma, ...);
- Simple mask or protection for the general population who need to leave their home for short period.
In case of lava flows, the health impact is minimal. The lava path is predictable and the progression is slow. It leaves plenty of time for people to evacuate.
Early warning systems, timely and adequate inter-sectoral interventions and co-ordination system need to be in place.