1.5.3 - Volcanic Hazards Flashcards
What is a Volcano?
A volcano is an opening in the Earth’s crust that allows magma, hot ash and gases to escape. Volcanoes can look like mountains or small hills.
How does a volcano form?
1) Magma rises through cracks or weaknesses in the Earth’s crust
2) Pressure builds up inside Earth
3) When pressure is released, as a result of plate movement, magma explodes to the surface causing a volcanic eruption
4) Lava from the eruption cools to form new crust
5) Over time, after several eruptions, rock builds up and a volcano forms
What is a magma chamber?
Store of magma underground
What is a vent?
The ‘tube’ whereby magma rises to the surface
What is a crater?
Opening at the top of the volcano
What is lava?
Molten rock at the surface that comes out of the volcano
What is a volcanic bomb?
Hot ‘lumps’ of rock forced from the volcano during an eruption
What is ash, steam and gases?
Released from a volcano during an eruption
Describe layers of ash and lava
Cooled to form the cone shape of the volcano
How do we know a volcano is going to erupt?
- Seismic activity
- Gas
- Magma
- Lava can pool into a vent
- Change in soil temperature + acidity
- Change water temperature + acidity
Define ‘ash’
Fine particles and dust ejected during an eruption, which can remain airborne as clouds or accumulate on the ground.
Define ‘convection currents’
The circulation of magma within the mantle (asthenosphere). Magma is heated by radioactive processes in the core and cools at the surface, and so circulates between the two places.
Define ‘hot spot’
Volcanoes found away from the plate boundary, due to a magma plume closer to the surface.
Define ‘lahar’
A flow of mud and debris.
Define ‘pyroclastic flow’
A mixture of gases and rock fragments, at high temperatures travelling at rapid speeds.
