2.a extrusive and intrusive landforms Flashcards
What are the 8 hazards produced by volcanos?
- lava flows
- pyroclastic flow
- gas emissions
- Tephara
- Ash
- lahars
- Flooding
- Tsunami
Explain lava flows as a hazard produced by volcanos?
Basaltic lava is free flowing and can run for considerable distances - low viscosity /Andesitic lava flow - does not flow as far /Everything in the path of the lava is burned,bulldozed,buried
Define pyroclastic flows?
A combination of very hot gases (500*c) + ash and rock fragments traveling at a high speed 100km/h+.
How can pyroclastic flows be a hazard?
Destroys everything within their path /Damaging to people due to inhalation due to poisonous gas + ash - causing fatalities
Explain the gas emissions hazards
Carbon . CO2, sulphur dioxide, carbon monoxide
* Deadly but silent threat as are not able to be seen /Sulphic acid combines with atmospheric water and acid rain is produced.
Define the term tephra
Material ejected from a volcano into the air that ranges in size
How are tephras hazardous
Potentially very hazardous
Can destroy crops
Columns of it can eject into the atmosphere - insanely hot
Identify a place where tephras are located
Iceland
Define the term lahar
A type of mudflow with consistency of wet concrete → but water is needed so when snow melts during eruption causes this rapid movement
How can lahars be a hazard
Picks up rock fragments as it moves down the volcano /Speeds of 50 km / hr /Everything in its path is destroyed or buried
explain flooding as a hazard
Volcanic eruptions beneath a field or glacier causes rapid melts e.g Iceland → due to this glacial melt
Explain tsunami as a hazard
Violent eruption of some island mass can cause massive displacement of ocean water causing speeds of up to 600km/hr / When they break send vasts amount of energy onto shore.
What is meant by etrusive landforms?
Extrusive → activity that occur on the surface of the earth
What are the four etrusive landforms you need to know?
geysers / hot springs and mud pools mud volcanoes fumaroles
What is a geysers?
There Is a fountain of both hot (often boiling) and cold water as well as steam ejected from the ground.
There has to be a powerful heat source beneath them relatively close to the surface and a source of water.
Facts about geysers
Rarest form of geothermal activity / Can rise to over 100m in height As the water moves towards the surface pressure decreases which reduces the boiling point of the water causing the eruption
What are the two other types of geysers
Fountain geysers are more violent eruptions whilst Cone geysers are where it erupts from silica and other sediments (sinter)
Explain hot springs and mud pools
Natural spring where the temperature of water is above body temperature which are not explosive / Surface material is rich in permeable volcanic ash and clay and when with a source of water = mud pools
Explain mud volcanoes landform
Mud pools splatter outwards to the sides which can result in the formation of ‘mini volcanoes’ 2m tall
Hot water mixes with mud and is deposited at the surface –> Tend not to be violent
What is a fumarole?
Vents that give off gases - CO2, Sulphur dioxide, hydrogen sulphide & steam that occur in areas of little water but lots of heat.
Facts about fumaroles
Created when super heated water reaches the surface
and Decrease in pressure changes water to steam
They are also accompanied by a roaring sound