Tectonic plates and Volcanoes Flashcards
What are the layers of the earth?
Inner core, outer core , mantle , crust
What are the types of plates?
Oceanic and Continental
What are the characteristics of oceanic plates?
Density , basaltic rock, 7km deep, sima and plates are destroyed
What is the aesthenosphere?
Upper part of the mantle
What is a hot spot?
Places where magma rises through the crust
What is the Lithosphere?
the outer part of the earth, consisting of the crust and upper mantle.
What are the type of north poles?
Grid north, polar north, magnetic north
What are S waves?
S-waves, secondary waves, are a type of seismic wave that move through the Earth during an earthquake.
What are p waves?
Primary waves, longitudinal waves from compression
What type of plate is Sial?
Continental
What is Sima?
silica (Si) and magnesium (mg)
What is Sial?
silica (Si) and aluminum (Al).
How are convection currents created?
Convection currents are movements of gases or liquids in a circular pattern, caused by heating and cooling
What are convection currents?
Convection currents are heat-driven cycles that occur in the air, ocean, and mantle.
What is Moho discontinuity?
boundary between the crust and mantle
What are the characteristics of Continental plates?
Grantic 35km, Sial, thick
Which way do destructive(convergent) plate boundaries move?
Plates move towards each other
Which way do constructive (divergent) plate boundaries move?
Tectonic plates are moving away from one another.
Which way do conservative plates move?
where two crustal plates slide past each other.
What are transform fault boundaries?
a fault between two plates of the lithosphere, which will slide past one another
What is the focus?
The focus is where the pressure is released underground and where the energy radiates out from. Starting point
What is the Benioff zone?
Zone where lithospheric plate is subducted
What is an example of a destructive plate margin?
Japan
What is an example of a constructive plate margin?
San Andreas
What is Moho discontinuity?
Boundary between the crust and the mantle
How does ridge push occur?
Mid-ocean ridges ( constructive boundaries) pull apart, => magma rise and create slope=> New rock, cools & becomes denser, => slides down and pushes the plates
How does slab-pull occur?
Destructive plate boundaries, oceanic plate sinks into the mantle , pulling the rest of the plate
What are the different movements in plate mechanisms?
Convection currents , slab pull, ridge push , gravitational sliding
What are the different landforms in plate movements?
oceanic ridges, volcanoes , oceanic trench, young fold, island arc
How are oceanic ridges formed?
new ocean floor is created as the Earth’s tectonic plates spread apart.
How are oceanic trenches formed?
Trenches are formed by subduction, in which two or more of Earth’s tectonic plates converge and the older, denser plate is pushed beneath the lighter plate
What are shield volcanoes?
a broad volcano with shallow inclining sides
What are cone volcanoes?
a triangle-shaped hill formed as material from volcanic eruptions piles up around the volcanic vent, or opening in Earth’s crust
How are shield volcanoes formed?
repeated eruptions that occurred intermittently over vast periods of time
How are cone volcanoes formed?
They form after violent eruptions blow lava fragments into the air, which then solidify and fall
How are young fold mountains formed?
where two or more of Earth’s tectonic plates are pushed together
How is an island arc formed?
from volcanic activity along a subduction zone
When do destructive plate margins occur?
when oceanic plate boundaries slide beneath the continental plate
When do conservative plate margins occur?
when plates slide past each other
When do constructive plate margins occur?
When plates move apart, magma rises and fills the gap thats been created
How is a rift valley created?
When the crust pulls apart, and the land drops, creating a rift valley
What is sea floor spreading?
formation of fresh oceanic crust , created through new magma=> sea to spread
What are the features of destructive plate boundaries?
Volcanoes, Mountain ranges, ocean trenches
What are the properties of shield volcanoes?
Low silica content (45-55%), low viscosity, lava erupted
What are the properties of composite cone volcanoes?
High silica(>65%), higher viscosity. ash volcanic bombs, lahars erupted, pyroclastic flows
What is pyroclastic flow?
A pyroclastic flow is a hot, chaotic mixture of rock fragments, gas, and ash that travels rapidly (tens of meters per second) away from a volcanic vent
What is a lahar?
A mixture of volcanic material and water. Usually occur during rapid melting of ice following an eruption
How are composite volcanoes are formed?
Alternating eruptions of ash , tephra and lava, builds up volcano layers.
Where do you find destructive subduction plate boundaries?
Where a continental meets oceanic ( oceanic heavier than continental)
What landforms are found at destructive plate boundaries?
young fold mountains, deep sea trenches, island arcs, volcanoes
What are the different landforms at constructive plate boundaries?
Volcanoes, ocean ridges, rift valleys
How are hotspots made?
A hot mass of rising heat, weakness in a plate, magma rises to the surface
What is an earthquake?
An earth quake is when the ground moves or shakes, creating seismic activity
What are earthquakes measured in?
Product moment fit
What measurement is used for the impact of an earthquake?
Mercali scale
What is liquefaction?
occurs when the shaking causes loose or saturated soils to lose their strength, causing water to be released
How is a tsunami formed?
Tsunamis happen when the seabed and large columns of water are displaced by submarine earthquakes. These types of earthquakes usually happen at subduction zones.
What is the elastic rebound theory?
Elastic rebound theory explains how stress builds up in rocks along a fault until they break and release energy, causing an earthquake. Oceanic-Continental subduction
What rock type ae composite volcano?
Basaltic
What rock type are shield volcanoes?
Cryolitic/ Andesitic
What is the hazard management cycle?
How well a country will cope with the earthquake will depend on how they go through steps in this cycle
=> Response, recovery, mitigation and preparedness
What are the main secondary hazards from earthquakes
tsunamis, liquefaction and landslides
What are characteristics of tsunamis?
high velocity, drop in sea level, short amplitude, long-wave length , followed by a draw back in water
What is the debris of a lahar comprised of?
Water, volcanic ash, pyroclasitc flow
What are magma plumes?
A magma plume is an upwelling of abnormally hot rock within the Earth’s mantle that rises towards the surface.
