volcanoes- the hazards and effects Flashcards
What hazard is Lava flow and how is its speed determined
Primary hazard determined by the viscosity of lava and the amount of silicon dioxide it contains
Effects of Lava flow
infrastructure and farmland covered in a layer of lava
very hot will destroy anything in its path
Case study of lava flow
iceland 1873, molten material erupted from a fissure volcano causing 22% of pop to die from famine
What is pyroclastic flow
mix of hot rock, lava ash and gas moving at a very high temp and speed in air
Effects of pyroclastic flow
destroy anything in its path, caused most death as direction of path is unpredictable, most hazardous when side of volcano as closer to ground
What hazard is a Jokulhlaup
A secondary hazard
What is a Jokulhlaup
When an eruption under an ice sheet/ glacier causes it to melt a large volume of ice and water consequently flows downhill pushing out from under ice
Effects of Jokulhlaup
extremely large floods
spacial extent
how much room a hazard takes up, pyroclastic flow and gases beyond lahars and lava flows
Shield volcanos- where do they form and what kinda eruptions
form at divergent (constructive) boundaries with relatively gentle and effuse eruptions
Composite (strato) volcanos- where do they form and what do they involve
convergent (destructive) boundaries with pyroclastic flows and lava/ash
Super volcanos, how to identify and requirements
erupt at least 1000km cubed of material, form caldera (cone shape) and less frequent
What type of hazard is Ash fall/ tephra
Primary hazard
What is Ash fall/ Tephra
All the pieces of all fragments of rock ejected into the air by erupting volcano
Effects of Ash falls/ Tephra
Very disruptive
Can build up and cause:
-collapse of roofs
-poor visibility
-damage to crops
-respiratory problems
Case study of Ash fall/ Tephra
Eyjafjallajokull (2010) caused 100,000 flights cancelled worldwide
What type of hazard are volcanic gases
Primary hazard
What are volcanic gases and what are they composed of
Explosive eruptions, mix of gas involves water vapour, sulphur dioxide, hydrogen and carbon monoxide
Effect of volcanic gases
When they sink (after travelling) and accumulate it can be deadly
Case study of volcanic gases
In 1986 in Cameroon, co2 emissions killed 1700 people
What hazard is lahar
A secondary hazard
What is Lahar
A mass of rock, mud and water that travels quickly down the sides of a volcano caused when an eruption melts snow and ice or due to heavy rainfall
Effects of Lahar
Can erode away material and infrastructure in their path, serious economic and land damage
Case study of Lahar
Killed 20,000 people in 1985 Nevado del ruiz
