Primary hazards
- Nuess ardentes- a glowing cloud which forms on strato or composite volcanoes. This is where there is a collapse of a lava Dome on the edge of the volcano, which leads to an ash cloud of high temperatures flowing down the flanks of a volcano of speeds up to 40 mph. These can stop breathing and cover the flanks in ash.
- Tephra- these are pieces of debris which is thrown out of the eruption at great velocity. This hazard would happen at converging margins. The tephra is split into lapilli (3mm to 64mm) and anything above this is considered a lava bomb. The lapilli which is considered finer particles can enter air currents hence spread to other areas on a regional scale . Therefore, if the ash enters the global air currents, its impacts become regional. For example, the 2010 Icelandic eruption led to ash and debris entering air currents which blocked air navigation equipment, thus making flying difficult . Therefore, this led to flights being cancelled in the UK, which had a cost of up to 95 million pounds on the economy. Lava bumps which are larger pieces of rock which can have direct effects on life and can destroy infrastructure. In Goma, 14 villages were affected and the Goma airport was split into two.
- Lava flows- these are flows of magma which flowed down the flanks of a volcano. This is split into aa and pahoehoe flows. Aa flows are the faster of the two flows, therefore can produce moreover hazard. These flows have a crustal rock on the outside which breaks off and falls in front of the direction of flow , hence it melts back into the main lava flow. Therefore, is able to move at faster speeds and cause more damage. Pahoehoe flows are low silica, runny lava which is of lower temperature. As a result, calls much faster forming a rock formation. In Nyriagongo, it’s the pahoehoe flow which had inundated 2 metres of parts of Goma.
- Lahars- these form when there is a suitable body of water on the flanks of the volcano. When the ash and debris enter the body of water, it turns into a muddy water which contains lava blocks. As a result, as it flows down the flanks of the volcano becomes a battering ram.
- Pyroclastic ash fallout- where a mushroom cloud of ash is dispersed into the atmosphere leading to ash falling down onto the surface.
- Acid rain- this is when sulfuric gases which are released into the atmosphere dissolves into water vapour. Therefore, when the water vapour condenses it produces cumulus limbus clouds which lead to acid rain. This rain can have local or national impacts depending on the air currents, but the acid rain can enter water courses leading to more long term damage.
Secondary hazards
- Climate change- when the ash and debris enter the atmosphere, it rises up into the stratosphere and blocks incoming solar radiation. Therefore, this leads to cooler surface temperatures which would have a reverse effect on climate change. This would have to be a plinian eruption to have such global consequences like the mount Tambora eruption in 1816, which led to the year without summer.
- Tsunami- if the volcano is near a coastal environment like at a continental and oceanic plate, then the lava bombs produced will enter the oceans to produce a tsunami wave.
- Flooding- this is where the ground shaking caused by the eruption leads to cracks appearing in dams which produce flooding. Where there is a glacier on the side of a volcano , which melts under the heat of the magma and flows down the volcano.