Flashcards in Tectonics- Lesson 5 Deck (18):
What type of volcano is Mt. Nyiragongo?
What percentage of all volcanic eruptions is Mt Nyiragongo responsible for?
When were Mt Nyiragongo's main eruptions?
1977 and 2002
Where is Mt Nyiragonga?
How many people were killed and evacuated in the 2002 eruption?
How wide is the lava lake?
How is the viscosity of lava determined?
It's determined by the amount of silicon dioxide
What happened as a result of the lava wall breaking in 1977?
The lava drained out for 1 hour
It flowed at 6km per second across 9 km swamping villages whilst people were asleep
What causes Lahars to form?
High levels of H2O vapour causing high levels of rainfall
How is SO2 a volcanic hazard?
The particles gets into the stratosphere.
It also produces acid rain which corrodes and affects vegetation
How is fluorine gas dangerous?
At high concentrations, its poisonous.
It contaminates farmland and water supply
How can ash affect local regions?
Most of it falls locally on villages. This causes roofs to collapse. It can choke machinery and other electronics. It also causes respiratory problems. It also buries vegetation.
How can ash disrupt on a global scale?
Ash can get carried via the jet stream causing it to travel irate distances. It can disrupt flights - can cause the abrasion of fuselages and engine blades
How fast are lahars?
What are pyroclastic flows?
Frothing bubbles of molten magma in the vent burst explosively.
Ejects a dense mixture of hot gases and pyroclastic material e.g. Shards, pumice, crystals
What temperatures can pyroclastic flows reach?
How do pyroclastic flows cause secondary hazards?
Volcanic deposits are lefts behind which are up to 200m thick.
Secondary hazards include damming rivers.