Overview
Volcanoes emit a variety of products which may be harmful to human and animal health. Some cause traumatic injury or death and others may trigger diseases, particularly in the respiratory and cardiovascular systems, or mental health problems. The impact on health is related to the style of eruption and type of volcano. Effusive eruptions tend to emit gases and aerosols, which may damage the respiratory system, and lava flows which rarely kill but may cause thermal injuries and mental stress due to the threat of loss of property. Explosive eruptions kill, injure and potentially trigger disease via a multitude of hazards ranging from proximal impacts related to production of fragmented rock and more distal impacts from ash, gas and secondary effects.
Injury agents
Injury and death are caused by a range of volcanic hazards (e.g. Auker et al. (2013)), which can be summarised by their impact on the body:
1) Mechanical injury where the body is crushed. Explosive eruptions may produce large volumes of fragmented rock, which range in size from boulders to fine ash. Mechanical injury/death occurs from a range of volcanic processes relating to the ejection of material and its transport through air or water (lahars, rock avalanches, ballistics). In 1985, the eruption of Nevado del Ruiz volcano, Colombia, led to glacial melt mixing with ash/rock deposits to form a lahar which buried 23,000 people downstream in the town of Armero. Roof collapse is also a common crushing injury, from the weight of ashfall, particularly on flat roofs [see Chapter 12]. Occasionally those proximal to the volcano may be buried by deposits or suffer asphyxiation from inhalation of particles.
2) Thermal injury (burns) caused by hot volcanic emissions. These take the form of pyroclastic density currents (PDCs) and surges (composed of searing gas, ash and rocks), lava flows and hydrothermal waters (which are used for recreational bathing). On Montserrat, West Indies, most of those killed during the Soufrière Hills eruption died on 25 June 1997 when PDCs and surges swept into the exclusion zone, where locals had returned to maintain their farms.