Volcanic Hazards Flashcards
What are the smallest fragments erupted from a volcano called?
Ash
Ash can be carried around the planet in the atmosphere.
What can heavy ash falls cause to buildings?
Roofs to collapse
Ash can also damage machinery and electronics.
How do ash clouds affect aviation?
They disrupt flight paths and damage engines and fuselages
Ash can cause significant hazards for aircraft.
What is a common volcanic gas that may condense locally?
Water vapour
It can mix with other erupted materials.
What gas is known to cause ‘acid rain’?
Sulphur dioxide (SO2)
SO2 is poisonous in high concentrations.
What is a pyroclastic flow?
A dense mixture of superheated solid particles and poisonous gases
Pyroclastic flows are considered the most dangerous volcanic hazard.
What speeds can pyroclastic flows reach?
Up to 700 km/h
They can destroy buildings and people in their path.
What are lava flows?
Molten magma that flows down the sides of volcanoes until it cools
Basaltic lavas flow fastest.
What are lahars?
A mixture of water and erupted volcanic material that flows rapidly down river valleys
Lahars can reach speeds of 60 km/h.
What triggers a jokulhlaup?
A volcano erupting underneath an ice cap
Meltwater builds up and eventually bursts out, flowing rapidly to lower ground.
Fill in the blank: Pyroclastic flows consist of a dense mixture of _______ and poisonous gases.
Superheated solid particles (tephra)
This mixture can move at great speeds and is extremely hazardous.
True or False: Lava flows are typically fast enough to cause many fatalities.
False
People can usually escape unless they are asleep or new eruption locations open up.
How do lahars pose a hazard to settlements?
They flow very fast down river valleys where settlements are usually located
Lahars can be difficult to escape even from a distance.
What can happen to river channels due to pyroclastic flows?
They may block river channels and cause flooding
This can lead to additional hazards beyond the flow itself.
