what are 3 types of plate boundary
constructive - plates move apart
conservative - plates move past
destructive - plate subducts
what is an intraplate earthquake/volcano
occur in the middle of the plate and are associated with ancient faults. theyre the result of crust cracking and newer faults can cause new plate boundaries
what are intraplates a result of
mantle plumes - stationary upwelling of abnormally hot rock within the mantle
hot spots - where plume meets the mantle
what is the theory of mantle convection
heat rises from the core where temps are over 6000 degrees. as it rises, it cools and creates convection currents and sinks back into the mantle
what is sea floor spreading
new crust is formed at mid-ocean ridges, the mantle crust pushes the plates apart. (ridge push is a part of sfs)
what is paleomagnetism
magnetic fields change every 400,000 years, leaving imprints in the rock which show the magnetic orientation of the new crust
what is subduction
the earth doesn’t expand due to sfs since new crust is created at mid-ocean ridges, it is being destroyed by subduction as the end of the plates sink
what is slab pull
the driving force between movements, new material cools and becomes denser as plates sink into the mantle and pull the rest with it
what are the 3 types of earthquake waves
primary waves
secondary waves
love waves
what are p waves
when tectonic stress energy is released. they are the fastest and cause the most damage
what are s waves
they make the ground shake violently. they are the slowest
what are love waves
they only travel across the surface and have a large amplitude. they create significant damage, including crustal fracturing
what are the characteristics of basaltic lava
very hot iron rich and silica poor
low gas content
runny hot lava
erupt continuously
not very explosive
create shield volcanos
what are the characteristics of andesitic lava
hot iron poor and silica rich
sticky and take centuries between eruptions
can be very explosive
what are the characteristics of rhyolitic lava
cooler lava
iron poor and silica very rich
high silica and low temps mean high gas content - combustible
erupt rarely but devastating
name the primary hazards of volcanos
lava flows
pyroclastic flows
ash falls
gas eruptions
name the primary hazards of earthquakes
crustal fracturing
ground shaking
name the secondary hazards of volcanos
lahars
jökulhlaups
name the secondary hazards of earthquakes
tsunamis
liquefaction
landslides
