Layers of the Earth
What are the three main layers of the earth?
Crust, Mantle, Core
What are tectonic plates and what can they be composed of?
Large slabs of rocky material
Can be only oceanic crust but most plates are composed of both oceanic crust and continental crust
Where do almost all earthquakes occur?
Along plate boundaries. Location of greatest stress on the rock in earth's crust.
What is a volcano and what is lava?
Volcano-Opening in Earth's surface where magma and other materials are released.
Lava- magma that has been released onto Earth's surface.
What is the instrument called the measures earthquakes?
Seismograph
What is the Lithosphere composed of?
Outer layer of solid rock that is composed of crust and part of the upper mantle
What enables the tectonic plates to move?
The asthenosphere.
The plates can move on the hot material as it flows.
What is an earthquake?
Movement's in the Earth's crust can squeeze, stretch or twist the rock, which applies pressure to the rock. When pressure it applied too quickly or is larger than the strength of the rock- the rock breaks. Stored energy in the rock is released as an earthquake.
Fault- break in the rock
Where are two locations that volcanoes can form?
Most volcanoes form at convergent boundaries:
- Oceanic- oceanic convergent boundary
- Oceanic- continental convergent boundary
What is the magnitude of an earthquake?
A number that represents the strength of an earthquake?
What is the Asthenosphere layer?
Layer that is made up of extremely hot material that behaves like plastic
Name and describe the three plate boundaries.
Convergent- when two plates collide and the more dense plate slips under the less dense plate (called subduction). Causes deep sea trenches.
Divergent- Where tectonic plates move apart and form new oceanic crust. Occurs where the sea floor spreads along a mid-ocean ridge. Can also occur in continents.
Transform- Where two tectonic plates slide past each other horizontally.
Name and describe the three types of faults.
Reverse fault- forms when rock is squeezed together and one block rides up to overlap the other block. Crust is shortened horizontally. Arrows pointing together.
Normal fault- forms when rock is pulled apart and one block slips downward. Crust is lengthened. Arrows pointing apart.
Strike-slip fault- forms when blocks of rock slip past one another horizontally.
What is the process of volcano formation at a oceanic- oceanic convergent boundary?
One oceanic plate collides with another and one subducts underneath the other plate. Ocean trench forms where one plate subducts beneath the other. Magma rises to the upper plate and is released onto the surface. Overtime, erupted lava and ash build up and form a curved group of volcanic islands. Example, Aleutian Islands of Alaska.
What is the Richter scale?
A scale for reporting the strength of an earthquake. Based on the size of the largest seismic waves that are formed. Higher number means greater strength. Each number represents a 10-fold difference.
How does density change in each layer (crust, mantle core)?
Crust- Lease dense layer (oceanic crust more dense than continental crust)
Mantle- Density increases with depth due to increasing pressure
Core- Most dense layer (heaviest material)
Describe how mantle convection drives plate tectonic movement.
Warmer less dense material rises.
Cooler more dense material sinks.
Causes large convection currents in the mantle.
As the mantle material moves, it drags the plates above along with it.
What and where is the focus and epicentre of an earthquake?
Focus- point where earthquake starts. The point where breakage of rock inside Earth first happens.
Epicentre- point on the Earth's surface above the focus.
What is the process of volcano formation at an oceanic-continental convergent boundary?
Oceanic crust collides with continental crust. Oceanic crust subducts beneath continental crust. Volcanoes form on the surface of continental crust. Magma can rise to the surface and cause an eruption. The pressure causes squeezing of crust for hundreds of km. Cause crust to fold and crumple producing large volcanic mountain ranges.
Massive mountain ranges are formed when two continental plates collide. One plate is shoved under the other (not easily). Impact causes a large area to be pushed up forming mountains.
What is the composition of each layer (crust, mantle, core)?
Crust- Solid rock made up of mostly silicon and oxygen (oceanic crust- basalt, continental crust- granite)
Mantle- Hot softened rock, contains magnesium and iron.
Core- Mostly iron and nickel. Outer core is a slow flowing liquid. Inner core is a spinning solid.
What are the two processes that determine how mantle convection affects the movement of tectonic plates?
Ridge push- New material pushes older material aside, causing plates to move apart. Rising material spreads out as it reaches the upper mantle. Causes the lithosphere to lift and push tectonic plates apart at divergent boundaries.
Slab pull- Pulling of a tectonic plate due to gravity and subduction. As the leading edge of a subducting plate sinks, it pulls the rest of the plate with it and convergent plate boundaries. Gravity and convection assist this movement.
Name and describe the three types of seismic waves.
Primary (P)- Move the fastest. Are the first ones detected in an earthquake. Cause rock particles to move forward and backward. Can travel through liquids and solids.
Secondary (S)- Move slower than P waves. Cause rock particles to move up and down. Can only travel through solids.
Surface (L)- Slowest of the three waves. On the surface and often cause the greatest damage. Cause rock particles to move up and down and side to side. Can travel on the surface of the Earth (not through interior).
What is a hot spot and hot spot volcanic ranges?
Hot spot- hot regions of Earth's mantle where magma rises to the surface by breaking through weak parts of the Earth's lithosphere. Volcanoes can form above hot spots as magma rises and melts through Earth's crust.
Hot spot volcanic ranges- magma rises, melts through the crust and forms volcanoes. Motion of the plate drags the plume head. The hot spot remains in one location but the plate moves forming a chain of volcanoes. Example, Hawaiian islands.
How did the Himalayan mountain range form?
Formed because of a collision between the Eurasian plate and the Indian plate. Fast movement of the Indian plate would have caused a violent collision. Tallest mountain range on Earth.