Fragile World and ecosystems Flashcards
(38 cards)
How many layers are there of the earth and what are they?
4 - Crust, mantle, outer core and inner core
What are plates are how do they meet one and other?
They are what is in a divided crust and they meet at plate margins
What are the three different types of plates?
Constructive, conservative and destructive
What do the plates do at each of these plate margins?
Constructive - plates move apart, constructive where plates slide past each other, destructive - where the plates collide.
3 facts about the crust
Has an oceanic crust and continental crust, 5 km depth on oceanic crust and 70 km deep in continental crust, under the ocean is basalt and under continents is granite.
3 facts about the mantle:
It’s 3000 km thick, The magma in the mantle moves slowly slowly due to powerful convection currents, temperature of it is crucial to formation of tsunamis and earthquakes.
3 facts about the outer core:
Made up of liquid and iron, 2200 km thick and 5300°C, the iron is responsible for our electro magnetic field which helps us live.
3 Facts about the inner core:
7200 km thick, made of solid nickel and iron, heat originates radio active decay.
3 facts about the oceanic crust:
Sinks at mantle when both crusts meet, forms constantly at constructive plate margins, destroyed at destructive plate margins.
3 facts continental crust:
Doesn’t sink, 3.4 billion years old, cannot be destroyed
What happens in the earths core to make volcanic eruptions and earthquakes to occur?
Heat rises from the earths core, setting of convection currents up in the mantle. The convection currents can move the plates to the extent that it can trigger earthquakes and volcanos.
What happens at destructive plate margins and how do they trigger volcanic eruptions?
At destructive plate margins the oceanic plate is denser than the continental plate and sinks beneath it. It sinks into the mantle and melts. Meaning it will rise up thorough the continental crust and explode at the surface as a volcano.
What happens at conservative plate margins and how do they trigger earthquakes?
The two plates are side by side. They move at different rates per year and cause friction over time. Eventually there is a release of energy that slides a plate out of place because of the build up of energy which causes an earthquake.
What happens at constructive plate boundaries?
Two plates are moving opposite ways. This allows magma to rise in the gap that is created by the two plates. This allows the formation of volcanos.
What happens at a collision boundary?
An oceanic and continental plate come together going in the same direction. The continental crust crumples because of the collision and forms a fold mountain where volcanoes can occur.
What happened in Montserrat when a volcano erupted?
It was after an unexpected span of small eruptions it had a massive eruption in 1997 because of its volcanic arc which developed a destructive plate margin. At that specific plate margin the Atlantic plate was subducting under the Caribbean plate causing magma to rise to the surface and cause Montserrat to erupt.
What are some of the effects of this eruption?
Montserrat was uninhabitable, poor infrastructure, 19 dead, lack of tourism, ash caused lung disease.
What causes a tsunami?
The tsunami will form on a plate boundary. One plate in the ocean will subduct under another. An earthquake is triggered in nearby city’s and country’s and the tsunami begins to follow the earthquakes path.
Why does a tsunami wave get bigger as it gets nearer the shore?
The wave travels fast in the deep water but as it gets shallower it gets slower because of friction and taller because the back of the wave catches onto the front because of its speed and it goes towards shore and the wave eventually breaks.
How are volcanoes caused in destructive plate margins?
The trapped sea water turns into steam as the sub ducting plate melts into the magma and this raises the Cilicia levels. This means that when magma rises in the volcano and is blocked by a vent but because if the build up of pressure below the vent it blows off and the lava from the volcano explodes out.
How are earthquakes caused from constructive plate margins?
When the magma is connecting in the mantle it can solidify causing a sudden halt in the movement of the plates going in opposite directions causing an earthquake because of its release of energy.
What caused the earthquake in chile?
At a destructive plate margin the NASCA plate was sub ducting under the South American plate building pressure and eventually slipped under shifting the South American plate upwards casing a rift and causing an earthquake to happen.
What were the effects of the earthquake in chile?
Up to 500 killed, up to 12000 injured, some building stood and fell, power and water were cut temporarily.
How was chile prepared for this earthquake and how did they protect themselves when it happened?
Buildings were reinforced with concrete colours, government made a plan of what to do in the situation, earthquake drills were practiced frequently by cilvillians, they followed the procedure drop cover hold