Volcanoes, Earthquakes, Platetectonics Flashcards
why does the earth’s crust move?
because the hotter mantle below rises and the colder mantle on bottom sinks, causing a circular movement which moves the crust
what are the 4 types of plate boundaries?
1- Constructive/divergent - moving apart, magma in between plates solidifies & creates new land (SA, Africa)
2- Destructive - oceanic & continental, moving together, subduction, fold mountains
3- Collision - 2 continental moving together, major fold mountains, himalayas
4- Conservative/ transform - moving past each other, huge amount of friction, earthquakes
what is subduction?
when you have an oceanic plate, it is heavier because of the water, once it collides with a continental plate, it goes below because it is heavier and melts
what is the pattern of earthquakes and volcanoes?
earthquakes - all plate boundaries
volcanoes - don’t usually happen in collision as land gets too thick and magma can’t go through, and not usual in transform boundaries as they are too close and there is no gap
case study
volcano
mt st helena - state of washington USA
juan the fuca plate colliding with north american plate
why do people live near volcanoes?
touristic attraction - money, jobs – St Helena
fertile land because of the ash, allows for farming – Mt Etna Italy
mining – mt pinatabu philippines (sulphur mine)
source of energy in cold places such as iceland
some people have to live there as it can sometimes be cheap and they can’t afford anywhere else
some don’t want to move away from where they have lived for so long already
how can we reduce impact of volcanoes
prediction:
pre eruptions - smoke, gas emissions
pressure senses on volcano
plan/prepare:
emergency/evacuation plan
diversion trenches that take lava away
water to cool it down
protect:
rescue services
management after - shelter, water, services
get services running quickly
how can we reduce the impact of earthquakes
prediction: tilt meter can check any movement foreshocks animals can act strangely before historical events, patterns
plan/prepare:
emergency/evacuation plan
enforce regulations to make safer buildings
buildings with wide base, and that are able to sway
protect:
rescue services
management after - shelter, water, services
get services running quickly
what are factors that affect the damage caused by earthquakes?
size of earthquake emergency services building design and construction time of day education physical landscape wealth
