Tectonic Flashcards
How does convection currents lead to tectonic plate movements?
-Heat from the earths core causes the mantle material to become less dense
-mantle material rises towards the surface
-The rising convection current then spread beneath the plates and drag them apart, causing divergent plate movement
-The mantle material then loses heat and sinks towards the core
-Convergent plate movement occurs where the convection currents collide
-The materials then get heated up again, and the process repeats itself.
How does slab pull force contribute to tectonic plate movement?
-When 2 plates collide the denser oceanic crust gets pulled down by gravity as it subducts beneath the less dense crust
-The denser oceanic crust sinks deeper in the mantle under its own weight, pulling the rest of the plate with it, contributing to further convergence
What is evidence of seafloor spreading?
-When 2 plates move away from each other at divergent plate boundaries, seafloor spreading occurs.
-Magma from deep within the earth rises , through the mid ocean ridge
-New oceanic crust is formed
Where are the younger rocks found?
-Rocks nearer to the crest of the mid-ocean ridge are the youngest.
-Rocks further away from the ridge are progressively older.
What happens at the divergent plate boundary?
-2 oceanic plates move apart
-the decrease in overlying pressure causes parts of the underlying mantle to melt, forming magma
-Magma rises through weak areas in the crust to the earth surface, and fills gaps caused by the spreading plate.
-lava cools and solidifies to form basaltic rocks.
-The rocks makes up a new oceanic crust
AN example is North american plate and oceanic eurasian plate move apart.
this forms a mid-atlantic ridge
What happen at convergent plate boundaries?
-2 oceanic plates collide
-the less dense oceanic plate subducts beneath the other plate
-this forms a deep depression known as an oceanic trench.
-As the subducting plate sinks into the mantle, the high pressure forces water out of its oceanic crust. Water lowers the melting point of the overlying mantle, causing it to melt, forming magma
-Magma rises Through weak areas in the crust to the earths surface.
-This forms a chain of volcanoes, known as a volcanic island.
What happens at Continental-Continental Convergent plate boundaries?
-2 continental plates collide
- Subduction does not take place because continental plates are too buoyant to subduct
-Enormous pressure causes the rocks to be uplifted and buckled to form fold mountains
How do tectonic process result in earthquake?
-Rocks masses on either side of a fault are pushed by tectonic forces.
-friction causes them to get locked , and stress builds up.
-When stress exceed the strength of the fault ,the rocks snap or suddenly move to a new position.
-This sudden movement causes seismic waves to be released, resulting in ground shaking
What are the scales used to rate magnitude of earthquakes?
Richter scale
Moment Magnitude scale
How does the Richter scale calculate earthquake magnitude?
The Richter scale calculates earthquake magnitude using the height pf the largest wave recorded on seismometers.
How does the Moment Magnitude scale calculate earthquake magnitude?
The Moment magnitude scale rates earthquake magnitude based on the total energy released during the earthquake.
What happen at transform plate boundaries?
-Stress caused by the plate movement produces a fault, Which is a zone of fractures
-Earthquake occurs here as one plate suddenly slips past another.
-Magma does not rise to the Earth’s surface, hence there are no volcanoes
When does stratovolcano form?
-Stratovolcanoes are formed by high silica lava which is more viscous magma.
-As magma rises towards the earths surface, the dissolved gases in the magma cannot escape easily.
-More pressure builds up until gases explosively resulting in violent, explosive eruptions.
-As high silica lava is viscous, it travels a shorter distance before cooling and solidifying, the volcano has steep sides and a narrow summit.
When does shield volcano form?
-shield volcano are formed by low silica lava which is less viscous magma.
-As magma rises towards the earths surface, the dissolved gases in the magma can escape easily.
-less pressure builds up resulting gentle effusive eruptions.
-As low silica lava is less viscous, it travels a longer distance before cooling and solidifying, the volcano has has gently sloping side and a broad summit
How does increasing preparedness for response and recovery build community resilience? and what are the strategies to increase preparedness?
-Being prepared for disasters means knowing what to do in the event of a tectonic hazard so that the community can avoid the dangers associated with the hazards.
1.Raising public awareness of hazards through education as this provides people with knowledge of the hazards and how to response. For example taking temporary shelter from volcanic ash during an eruption and sealing doors and windows
2.Conducting first aid training, This enables people to administer basic medical care to the injured and keep them mobile so that they can evacuate if needed.
