Term 4 Exam Year 8 Semester 2 Flashcards
What causes earthquakes?
Earthquakes are caused by the build up and release of stress within strata.
What is elastic rebound?
As stress accumulates in ricks either side of the fault the rocks bend and distort until the earthquake occurs and the rocks snap back to their original state releasing energy that produces seismic waves.
What is the epicentre?
The epicentre is the place in the earths surface where the earthquake is first felt.
What is the focus?
The focus is the place inside the earth where the earthquake originates.
What are seismic waves?
Seismic waves are energy released during an earthquake.
What are the three different types of seismic waves?
P Wave - Primary Waves
S Wave - Secondary Waves
L Wave - Surface Waves
What is a P Wave?
Primary Waves Fastest Compressional Weakest Travels through fluids and solids
What is an S Wave?
Secondary Waves Slower Shearing (pulls rocks in opposite directions) Stronger Only travels through solids
What is an L Wave?
Surface waves Slowest Compressional and shearing Strongest Travels through solids only
What is the asthenosphere?
The layer of slow flowing hot semi-solid rock in the upper mantle.
What is a seismograph?
A machine that records earthquake activity.
What is a seismogram?
A record of earthquake activity.
What are the different types of plate boundaries?
Transform
Divergent
Convergent (oceanic oceanic, continental continental and oceanic continental)
What is a transform plate boundary?
When two plates slide against each other, these don’t make mountains or volcanoes but do produce lots of earthquakes. An example in real life is Los Angeles close to San Francisco (extra marks) where the North American plate is slowly moving downwards and the Pacific plate is slowly moving upwards, causing a transform boundary.
What is a divergent plate boundary?
A divergent plate boundary is where two plates move away from each other causing constant creation of new land. Plates move apart and the crust expands. When two pieces of crust move away from each other, molten rock rises into the opening. An example of this in real life is Iceland because Iceland is constantly growing in size due to it being in the middle of the North American plate and the Eurasian plate.
What is a convergent plate boundary?
A continental plate boundary is when two plates move toward each other?
What are the three types of convergent plate boundaries?
Continental continental, when to continents converge
Oceanic oceanic, when two oceanic plates converge
Oceanic continental, when an oceanic plate and a continental converge
What is a continental continental convergent plate boundary?
A continental continental plate boundary is when two continents meet head-on, the crust tends to buckle and be pushed upwards or sideways p. A real life example of this is the Himalayan mountains.
What is an oceanic oceanic convergent plate boundary?
An oceanic oceanic convergent plate boundary is when two oceanic plates converge, one is usually subducted under the other and in the process a deep oceanic trench is formed. Oceanic oceanic plate convergence also results in the formation of undersea volcanoes. A real life example of this is Mid-Oceanic ridges or rift valleys. Such as Mt. Kilimanjaro, Dead Sea, Sea of Galilee.
What is an oceanic continental convergent plate boundary?
An oceanic continental convergent plate boundary is when oceanic and continental plates move towards each other. When an oceanic plate pushes I to and subducts under a continental plate. Because it is more dense. The overriding continental plate is lifted up and a mountain range is created. A real life example of this is the Andes mountains.
What is convection?
Convection is when particles rise because they are heating up, they then move across as they start to cool and fall once it has cooled down, this process continues. One the particles have reached the top they have nowhere else to go forcing the tectonic plates to move apart. This happens in the mantle.
What is Sea floor spreading?
Sea floor spreading is when the old crust sinks down and new crust rises from the mantle to create new crust. This happens when the crust spreads out and new crust is formed.
