Tectonic hazards Flashcards
What is a natural hazard?
A natural hazard is a naturaal process which could cause death, injury or distruption to humans or destroy property and possesions
Extreme events which do not pose any threat to human activity are not counted as hazards (e.g a drought in an uninhabited dessert)
What is a natural disaster?
A natural disaster is a natural hazard that has actually happened
What are geological hazards?
Give examples
Geological hazards are caused by land and tectonic processes
They include volcanoes and earthquakes, landlsides and avalaches
What are meteorological hazards?
Give
Meterorological hazards are caused by weather and climate
They include tropical storms, extreme weather, hurricane and heatwaves
What is a hazard risk?
The probability of people being affected by a hazard in a particular area
How does vulnerability affect hazard risk?
The more people that are in an area exposed to natural hazards, the greater the probability they will be affected by a natural hazard
How does capacity to cope affect hazared risk?
The better the population can cope with an extreme event the lower the risk of them being severely affected
E.g. hics can afford to build flood defences
How does the nature of natural hazards affect hazard risk?
The risk of some hazards is greater than others
E.g. tropical storms can easily be detected and monitered whereas earthquakes can happen very suddenly
What are tectonic plates?
The earths crust is divided into slabs called tectic plates that float on mantle
The plates are moving because of convection currents
Destructive margins
These are where two plates are moving towards each other
Where an oceanic plate meets a continental plate, the denser oceanic plate is subducted (forced down into the mantle) and destroyed, creating gs rich magma. Volcanoes and ocean trenches occur here.
Constructive margins
Constructive margins are where two plates are moving away from each other. Magma rises from the mantle to fill the gap and cools, creating new crust.
Conservative margins
Conservative margins are where two plates are moving sideways plast each other or are moving in the same direction but at different speeds. Crust isn’t destroyed.
How is a volcano formed?
In a destructive margin
At dectructive margins, the denser oceanic plate moves down into the mantle, where it melts.
A pool of magma forms which then rises through cracks in the crust called vents
The magma (calld lava when it reaches the surface) erupts, forming a volcano
How is a volcano formed?
At a constructive margin, the magma rises up into the gap created by plates moving apart, forming a volcano
How are earthquakes formed?
By tension that builds up at all three types of plate margins
Tension builds when they get stuck while moving past each other. Tension builds along cracks in the plates as they move away from each other. Tension builds when plates that are grinding past each other get stuck.
The plates eventually jerk past each other sending out shock waves/vibra
