Plate Margins Flashcards
(25 cards)
What is a collision margin?
When 2 plates meet that are made of continental crust converge. Because neither is denser than the other, there is no subduction. Plates buckle up to create a range of fold mountains. There are no volcanoes because there is no rising magma but there are very powerful earthquakes.
What is the difference between primary and secondary hazards for earthquakes and give examples.
Primary hazards happens right away when the earthquake strikes such as ground shaking and buildings collapsing whereas secondary hazards happen because of the primary hazards, sometimes minutes, hours or days later such as tsunamis, fires, landslides etc.
What is the difference between primary and secondary hazards for volcanoes and gives examples of each.
Primary hazard happen straight away durning eruption such as lava flows, ash clouds, pyroclastic flows whereas secondary hazards happen after the eruption, often as a result of the primary hazards happen after such as lahars(mudflows), tsunamis, acid rain and crop failure.
What is the difference between continental and oceanic crust?
Oceanic crust is denser , thinner (on average 7km thick), mainly made of basalt and they are a lot younger, usuallly less than 20 million years old whereas continental crust is thicker, usually 30-50km and less dense and is older, can be billions of years old.
What are the key characterises of the inner core?
This part of the core is solid and is made up of metal, mainly nickel mixed with iron. This is the hottest part of Earth and is only 1260km thick.
What are the main characterises of the outer core?
This part of the core is liquid and is made of metal, mainly iron mixed with nickel . It’s about 2220km thick.
What are the main characteristics of the mantle?
The outer mantle is hard, but further in it is like soft toffee. This is the thickest part of Earth at about 290km thick . This is made of denser rock than the crust.
What are the main characteristics of the crust?
This is the thinnest layer, ranging from 8-65km thick. We live on the layer and it is made of less dense rock so it floats in the mantle.
What are the main processes and landforms of the constructive margin?
Two plates DIVERGING above the upward plume. Magma rises through the gap between the plates , resulting in volcanoes . Lava solidifies and cools to create a new crust. Eruptions and earthquakes are relatively gentle.
What are the main processes and landforms of the destructive margin?
Destructive margins occur where two plates, one made from oceanic , one from continental crust, are CONVERGING. When they meet, the oceanic dives underneath the continental because it is denser. This is called subduction. The sinking plate and can stuck due to friction leading to pressure which is released and resulting to earthquakes.
What are the main processes and landforms of the collision margin?
A collision margin occurs when two plates made of continental crusts CONVERGE. Neither plates are denser than the other so no subduction and the plates buckle up to create fold mountains. There are no volcanoes because there is no rising magma. There are very powerful earthquakes.
What are the main processes and landforms of the conservative margin?
Conservative margins occur when two plates move alongside in opposite or same directions. Friction can cause the plates to stick and pressure builds up and the pressure is released into powerful earthquakes. No volcanoes because no rising magma.
What is the focus?
The point underground where the plates slip and from where the seismic waves radiate outwards.
What is the epicentre?
The point on on the Earths surface dierectly above the focus. In theory shaking here would be strongest.
What are seismic waves?
Energy waves that radiate outwards from the focus and cause the ground to shake.
What is the Richter scale?
Measures the amount of energy released during earthquake. Each number on the scale means the earthquake is 10times stronger than the one before.
1–2 Tiny, not felt by people
3–4 Small, might be felt, no damage
5–6 Moderate, can cause damage
7–8 Strong, major damage likely
9+ Extremely powerful, widespread destruction
What is magnitude?
The magnitude is the amount of energy released by an earthquake at its source. Tells us how strong an earthquake is.
What is the magma chamber?
A large underground pool where magma(molten rock) collects beneath a volcano. When this starts to rise, an eruption is likely.
What is the primary vent?
The primary vent aka the main vent is the main opening in the volcano where lava, ash and gases come out during the eruption and also the ‘pipe’ connects the magma chamber to the crater.
What is the secondary vent?
The secondary vent is a smaller opening on the side of the volcano where lava, gas or ash can escape if the primary vent is blocked or if pressure finds another way out
What is the crater?
The opening at the top of the volcano where lava, ash and gases come out during eruption.
What is the parasitic cone?
It is a small cone shaped volcano that forms on the side of a larger volcano. It is made when lava and ash erupt from the secondary vent.
What are three reasons why people live in areas of volcanic hazards?
- Fertile soil for farming. Volcanic ash breaks down into soil that is rich in minerals, making it great for growing groups.
- Poverty- they have a lack of choices and cannot afford to live anywhere else so they stay there even if it’s is dangerous
- Confidence im prediction and monitoring- modern tech oncology can monitor volcanic activity so people feel safer because they believe they will get warnings before eruptions.
What are 3 physical that affect the severity of hazard impacts during an earthquake or a volcano?
- Larger magnitudes mean bigger earthquakes or stronger volcanic eruptions that cause more damage.
- If the earthquake happens close to the surface, it causes more shaking and destruction.
- If there is bad weather during or after the eruption/earthquake, it can cause mudslides or slow down rescue efforts.
