Earthquakes and Volcanos Flashcards
(32 cards)
What are tectonic plates?
Huge slabs of rock that form the Earth’s crust and float on the mantle.
Name the 2 types of tectonic plate:
Continental
Oceanic
What are the features of a continental plate?
Light and thick. They form land.
What are the features of a oceanic plate?
Thin and heavy. They form the ocean floors.
What is the movement of plates called?
Continental drift. The plates are floating on the magma.
The magma is moving with the convection currents generated by immense heat.
What is the name for where tectonic plates meet?
Tectonic plate boundaries.
What are the names of the 4 types of plate boundary?
Destructive
Conservative/sliding
Constructive
Collision
What are the features of a destructive plate boundary?
Where an oceanic and continental plate boundary meet.
The heavier oceanic plate sinks under the continental plate. Where they meet is known as the subduction zone.
Where the 2 plates rub together this creates friction.
When the forces become too great for friction to restrict the movement of the plates they move abruptly.
This causes an earth quake.
Volcanos could form where there is a gap in the plates at a destructive plate boundary.
What is the Earth made up of?
The Earth has four main layers - the inner core the outer core the mantle the crust.
What is the inner core of the Earth like?
The inner core is 5,500°C - extremely hot.
It is a very dense solid made from iron and nickel.
What is the outer core of the Earth like?
The outer core is 2,000 km thick and is a liquid.
What is the Earth’s crust like?
The crust is the rocky outer layer of the Earth.
It is thin compared to the other sections, approximately 5 km to 70 km thick.
If the Earth was scaled down to the size of an apple, the crust would be about the thickness of the apple skin.
What are the features of a constructive plate boundary?
A constructive plate boundary occurs when plates move apart.
Volcanoes are formed as magma wells up to fill the gap, and eventually new crust is formed.
Constructive plate boundaries can be formed between two oceanic or two continental plates.
What is an example of a constructive plate boundary?
The mid-Atlantic Ridge.
What are the features of a conservative / sliding plate boundary?
A conservative/sliding plate boundary, occurs where plates slide past each other in opposite directions, or in the same direction but at different speeds.
The plates can be both continental or both oceanic.
Friction is eventually overcome and the plates slip past in a sudden movement. The shockwaves created produce an earthquake.
What are the features of a collision plate boundary?
Collision zones form when two continental plates collide.
Neither plate is forced under the other, and so both are forced up and form fold mountains.
The Himalayas are a famous example of collision boundaries of the Indo Australian and Eurasian plates moving towards each other to form fold mountains.
Give an example of a famous collision plate boundary?
The Himalayas.
Give an example of a famous conservative / sliding plate boundary?
The San Andreas fault in California.
Give an example of a famous destructive plate boundary?
The Ring of Fire around the Pacific Ocean.
What are the names of the tectonic plates?
- Eurasian
- Pacific
- Indo-Australian
- African
- Antarctic
- South American
- North American
- Nazca
What are the main features of a volcano?
A volcano is an opening in the Earth’s crust. It allows hot magma, ash and gases to escape from below the surface.
- Magma chamber - large underground pool of magma
- Lava - magma, once it reaches the surface
- Crater - bowl-shaped basin in the top of the volcano
- Vent - central tube which magma travels through
- Secondary cones - eruptions from other vents may build up secondary cones on the flanks
- Ash, steam and gas - material thrown out by the volcano
- Volcanic bombs - larger material thrown out by the force of eruption
What are the 2 types of volcano?
Composite
Shield
What are the 3 classifications for volcanic activity?
Extinct – Volcano that has not erupted in the last 200 years and will not erupt again.
Dormant – Volcanos that have erupted in the last 200 years but not in the last 200 years.
Active - Have erupted in the last 2000 years and are likely to erupt again.
What are the features of a composite volcano?
Composite volcanoes are steep and made from layers of ash and thick sticky lava.
They occur on destructive plate boundaries.
The eruptions are violent. Ash and lava are ejected into the air. Building up layers of ash and lava.
Pyroclastic flows of hot gas and ash travelling at more than 100 miles per hour can flatten and burn everything in its path.