Volcanic hazards

• Volcanic hazards cause damages to lives and properties.
• Understanding volcanic hazards -- how these behave, and how each of these can specifically put us at risk -- is key to preventing future disasters.
• Likely the most popular volcano phenomenon, lava flows are molten rocks coming out from a volcano’s central vent or crater. These flow downslope or along existing channels.
• Mafic lavas flow at less than 1 km/h on gentle, unconfined slopes; and at less than 10 km/h if the slopes are steep.
• However, mafic lava can reach 30 km/h if it travels on a confined channel
• Lava flows pose minimum risk to people’s lives since humans, at an average marathon speed of 20 km/h, can easily outrun this hazard.
• However, forests, farms, large infrastructures, and fixed properties in the path of lava flows are very likely to be buried and burned.
• Apart from lavas, gases are also released by volcanoes.
• The most common volcanic gases are water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2). Hydrogen sulfide (H2S) and hydrogen halides are also emitted.
• If you have gone to an active volcanic area before, you may have encountered the smell of rotten eggs which is characteristic of hydrogen sulfide.
• Volcanic gases pose risks to people, animals, and even plants.
• There are cases when gas released by a volcano may be denser than the surrounding air (for example, cold CO2), and may accumulate in nearby depressions or low areas.
• Humans breathing air with 15% CO2 may quickly lose consciousness, and instantly die by asphyxiation.
• One of the most documented case of disasters due to volcanic gases happened in August 1986 in Cameroon, when Lake Nyos, a volcanic crater, emitted a dense cloud of CO2, killing at least 1700 people (and animals too) within a distance of 20km away from the lake (Edmonds et al., 2018).
• The Philippine Institute of Volcanology and Seismology is currently monitoring Pinatubo and Taal volcanoes for CO2. These volcanoes have large crater lakes which have the potential to store and later release CO2 in the same manner as Lake Nyos.