System Earth Ch 07 Flashcards
(36 cards)
seismology
the study of earthquakes and related phenomena
earthquakes
the rapid release of stored energy as a result of quick movement between rocks. Can be as deep as 700km below surface
fault
fracture caused by an earthquak
surface waves
travel along the earth’s surface and transmit earthquake energy
body waves
travel through the earth and are categorised as P or S waves
P waves
longitudinal
they can travel through the earth’s core but also through the crust. They provide the estimate for how big the core is
S waves
are transverse waves. They cannot travel through the earth’s core. Can only travel through solids. The furthest they travelis 103 degrees from where they were emitted.
mohorovcic discontinuity
difference in earth’s crust thickness
continental vs oceanic crust
continental is thicker but less dense. They differ in chemical and meteorological compositions as well.
igneous
cooling and solidification of magma. If this occurs below the earth’s surface, it is an intrusive rock
lithification
conversion of loose sediment into rocks (sedimentary rocks who would believe it)
sedimentary rocks
compacted sediment bigger than sand
metamorphic rock
rocks that form under high pressure. As long as no melting is involved, it’s metamorphic
major rock forming minerals
feldspars, quartz, olivine, pyroxene
what type of rock covers most of the earth’s surface
sedimentary
mantle
a seismic low velocity zone exists
mantle rotates in the same direction as the earth
core
is made up of iron, nickel and ligth elements. It is much denser than the mantle, changing its seismic wave velocity. It is the source of earth’s magnetic field.
earth’s magnetic field
in the core, like a dynamo, transforms energy into fluid motions. The liquid outer core convects and conducts electricity. The solidification of iron releases heat, allowing for a liquid iron core.
mid ocean ridges
has a rift and is an indicator of seafloor spreading
lithosphere and asthenosphere
upper crustal part of the lithosphere is brittle. Below this is the asthenosphere, a region of the upper mantle that acts more like a fluid than a solid. It is ductile.
divergent margins
constructive plate boundary
rift vallyes, lava rises and cools, forming new land
triple junction is if there is a centre point of the margin
convergent margin
destructive plate boundary. you get subduction of the denser plate and melting and slab pull and convection currents etc. the subducting plate creates deep sea trenches. you get a volcanic arc
convergent margin oceanic vs. oceanic
same thing but it’s called a volcanic island arc. Marianas trench is an example.
convergent continental vs. continental
neither can be subducted so you get a separation of crustal poition of the lithospheric plate from teh mantle bbelow. Subduction of teh mantle part might happen whil the continental crust compresses and crumples. This results in mountain formation like when india collided with asia.