Tectonic Processes and Hazards Flashcards
What is a Hazard?
A potential threat to human life and property
Where do Geophysical hazards occur?
Near plate boundaries
What is it called when Earthquakes occur near the middle of plates?
Intraplate Earthquakes
There are two main sub-sections of Natural Hazards. What are they called?
- Hydro-meteorological
- Geophysical
What are Hydro-meteorological hazards?
Hazards caused by climatic processes
What are Geophysical hazards?
Hazards caused by land processes
Name types of Hydro-meteorological Hazards:
- Floods
- Droughts
- Cyclones
- Blizzards
Names types of Geophysical Hazards:
- Earthquakes
- Volcanic Eruptions
- Sinkholes
- Tsunamis
Name the layers of Earth’s structure from the outermost to innermost layer:
1) Crust
2) Mantle
3) Outer Core
4) Inner Core
What is the difference between Oceanic and Continental Crust?
- Oceanic is thin and dense
- Continental is thick
What was Holmes Theory in 1929?
Radioactive Reactions occur in the Core, which produce Convection Currents in the Mantle. This is the force behind Continental Drift.
What was Alfred Wegener’s theory in 1912?
All continents were once joined in a super-continent called Pangea, however Continental Drift caused it to split apart. This is further verified by similar fossils found where these plates could have fit.
What is the Wadati-Benioff zone?
A dipping flat zone of Earthquakes that is produced by the subduction of Oceanic Plate under a Continental Plate
When does Sea Floor Spreading occur?
It occurs when two Oceanic Plates move away from each other, allowing magma from the mantle to rise and form new crust ridges within the ocean, resulting in the sea floor widening.
What is Palaeomagnetism?
The study of magnetic patterns in cooled magma within the sea floor that allign with the Earth’s magnetic field, and they reverse over millions of years. This helps date Oceanic crust and proves that the Earth did once fit together.
Name the 3 types of Plate Boundaries?
- Divergent
- Convergent
- Conservative
Describe a Continental to Oceanic Convergent Plate Boundary:
- The denser Oceanic Plate subducts below the Continental
- The plate subducting leaves a deep ocean trench
- Built up pressure from the melting plate cause explosive volcanoes bursting through the Continental Plate
Describe an Oceanic to Oceanic Convergent Plate Boundary:
- The heavier plate subducts leaving an ocean trench
- Built up pressure causes underwater volcanoes bursting through Oceanic Plate
- Lava cools and creates new land called Island arcs
Describe a Continental to Continental Convergent Plate Boundary:
- Both plates are not as dense as Oceanic Plates so lots of pressure builds up
- Ancient Oceanic Crust is subducted slightly, but there is no subduction of Continental Crust
- Pile up of Continental Crust on top of lithosphere due to pressure between plates
- Fold mountains formed from piles of Continental Crust
Describe an Oceanic and Oceanic Divergent Plate Boundary:
- Magma rises in between the gap left by the two plates separating, forming new land when it cools
- Less explosive underwater volcanoes formed as magma rises
- New land forms on the ocean floor by lava filling the gaps, which is known as sea floor spreading
Describe a Continental and Continental Divergent Plate Boundary:
- Any land in the middle of the separation is forced apart, causing a rift valley
- Volcanoes form where the magma rises
- Eventually the gap will most likely fill with water and separate completely from the main island
What is Ridge Push?
The slope that is created when plates move apart has gravity acting upon it as it is at a higher elevation. Gravity pushes the plates away, widening the gap.
What is Slab Pull?
When a plate subducts, the plate sinking into the mantle pulls the rest of the plate with it, causing further subduction.
Describe a Conservative Plate Boundary:
Between any Crust, the parallel plates move in different directions or at different speeds. No plates are destroyed, so no landforms are created.
