Tectonics Flashcards
What is a tectonic hazard
a tectonic event that has the ability to cause harm onto people or property
What is a plate boundary
distinct zones at the edges of tectonic plates where earthquakes usually occur
What are intraplate regions
an area where intraplate earthquakes occur due to a build up of stress by continental rifting or its transfer from other regions
What is a divergent plate boundary
where plates move away from eachother
What is a conservative plate boundary
where plates slide past eachother
What is a convergent plate boundary
where the oceanic crust slides under the continental crust
What makes a volcano more explosive
- higher silica content
- high viscocity
- lower temperatures
- more gas
- water content
What are characteristics of the continental crust
- made of less dense rocks
- created at destructive plate boundaries
What are the characteristics of oceanic crust
- made of denser rocks
- formed at divergent plate boundaries
What is the lithosphere
the fusion of the crust and upper most solid mantle
What is the aesthenosphere
the ductile/rheid layer of the Earth that allows the plate to move
What is the mantle
- 82% of Earth’v volume (aesthenosphere to outer core)
- made of silicate rock rich in iron and magnesium
What is the core made up of
- mostly iron and nickel
- outer = liquid
- inner = solid
What are deep sea ocean trenches
the point where oceanic plates subduct beneath continental plates
What are fold mountains
when subduction causes mainly sedimentary rocks to warp and be pushed upwards from collisions
What is the benioff zone
the area where earthquakes occur
What is subduction
when one edge of a plate is force beneath another
What are mantle plumes
abnormally hot rocks which are moving up the Earth
What are hotspots
when mantle plumes breach the surface and spew lava
What do mantleplumes/hotspots create
- intraplate volcanoes
- island arcs
What is the proof of Alfred Wegners theory of continental drift
- plates are puzzle pieces and create Pangea
- continents broke away and drifted apart
- tropical fossils sound in Antartica
- glacial deposits in Brazil/tropical/desert areas
- rock layers matching in different countries
- fresh water fossils found across oceans
What is seafloor spreading
the divergent motion of oceanic plates and rise of balsatic magma to produce mid-ocean ridges
How does paleomagnetism prove seafloor spreading
magma locks in the Earth’s magnetic polarity, which shows changes in geology
What is slab pull
- when dense oceanic crust becomes heavier than the aesthenosphere and descends at subduction zones
- the weight of the sinking cooling plate causes a major pulling motion
What is ridge push
- when plates are hotter and less dense than their surroundings and rise
- form mid-ocean ridges
- slide sideways off high areas
- pushes plates infront of them
What is the modified Mercalli scale
- a measure of intensity
- based on the observations of people who experienced the event
- I-XII
What is the Moment Magnitude Scale
- a measure of the total energy released by an earthquake as soon as it occurs
- 1-10
- logarithmic
What is the Volcanic Explosivity Index
- a logarithmic scale that measures a volcanoes column height, volume of tephra released, and qualitative observations
- 0-8
What is the hypocentre/focus
where the stress is released
What is the epicentre
the point directly above the hypocentre
What are the characteristics of P-Waves
- fastest
- reach the surface first
- compressional waves
- travel through liquids and solids
What are the characteristics of S-Waves
- slower than P-waves
- only pass through solids
- lateral movements
What are the characteristics of L-Waves
- slowest
- cause the most damage
- high amplitude
Why does felsic magma contain more silica, allowing it to produce more explosive eruptions
form at convergent boundaries where continental and oceanic crust is melting
What are primary hazards
hazards that occur during the natural disaster