Dynamic Earth 9 Flashcards
Define a fossil
Any evidence of once-living organisms from the distant past
Define a focus
The point of origin for the energy released from an earthquake
Outline the supercontinents in order
- Pangea
- Gondwana
- Pannotia
Describe the evidence of continental drift
- The same fern was found of 5 continents
- Rock types align along South America and Africa where they used to be connected
- Fossils of certain animals had been found in Antarctica, India and Africa
Outline the structure of the Earth from the outside inwards
- Crust (thick, solid)
- Mantle (deep, semi-liquid)
- Outer core (thick, liquid)
- Inner core (solid)
What is the difference between the lithosphere and asthenosphere?
The lithosphere consists of the crust, plates and upper-solid crust. The asthenosphere is the liquid that tectonic plates slide over. The asthenosphere is also part of the upper mantle.
Outline how convection currents in magma move tectonic plates
As the hot outer core heats up the mantle at the bottom, the hot mantle rises until it cools down and falls back down again
What is this?
Convection currents
What is plate divergence?
Plates moving away from each other
What is plate convergence?
Plates moving towards each other
What is plate transformation?
Plates sliding against each other
Describe the effects, structures created, and volcanic activity in plate divergence
Effects - constructive (creates rock)
Structures created - ridge/rift
Volcanic activity - yes
Describe the effects, structures created, and volcanic activity in plate convergence
Effects - destructive (rock destroyed)
Structure created - trench
Volcanic activity - Yes
Describe the effects, structures created, and volcanic activity in plate tranlsation
Effects - conservative (rock neither created not destroyed)
Structures - None
Volcanic activity - none
What is this?
Plate divergence
What is this?
Plate convergence
What is this?
Plate translation
Define an earthquake
A sudden, rapid shaking of the Earth due to the release of energy stored in rocks
What is the Richter scale based on?
The earthquake’s intensity
What is the Mercalli Scale based on?
The effects that the earthquake had on humans and the destruction caused
Define Epicentre
the point on the earth’s surface vertically above the focus of an earthquake
What are the 3 types of seismic waves?
S waves, P waves, and L waves
Outline the type of wave, relative speed and materials able to be travelled through of S waves
Type of wave - transverse
Relative speed - slower
Can travek through - solids only, can’t move through liquid outer core
Outline the type of wave, relative speed and materials able to be travelled through of P waves
Type of wave - longitudinal
Relative speed - faster
Can travek through - solids & liquids, can move through liquid outer core
Describe L waves
Last to arrive, surface waves that can travel through the crust only, almost entirely responsible for earthquake destruction, the deeper the focus the less the strength of L waves
What is the green?
Areas of earthquake activity
What is the blue?
Rift Valley
What is the pink?
Ring of fire
What is the purple?
Mid-atlantic ridge
What type of waves is the right side?
P waves
What type of waves is the left side?
S waves
Describe 4 secondary dangers from a volcanic eruption
- landslides
- tsunamis
- water contamination
- wildfires
What is the ring of fire?
A path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes.
How can a volcanic island form?
As volcanoes erupt, they build up layers of lava that may eventually break the water’s surface. When the tops of the volcanoes appear above the water, an island is formed.
What is the difference between dormant and extinct volanoes?
Dormant volcanoes have not erupted in a long time but are expected to erupt again in the future. Extinct volcanoes are those which have not erupted in human history
Outline the DART system
- a tsunametre detects the change in water pressure caused by a tsunami
- this sends a signal to the DART surface buoy
- This signal is sent via satellite to the Tsunami Warning centres where an alert is issued
What is the Rift Valley in Africa?
The Rift Valley in Africa has magnetic minerals which preseverd the Earth’s magnetic fingerprint as they cooled & hardened into rock
