Earth Interior Flashcards
What is Geophysics?
It is the branch of Geology that studies the earth’s interior.
What are Seismic waves?
They are the form in which energy is transferred from earthquakes and they occur as a result of breakage at the faultline. They can travel all around the globe.
What is Seismic Reflection?
The return of some waves to the surface after bouncing of a rocky layer in the earth.
What is Sesimic Refraction?
bending of
seismic waves as they pass from
one material to another having
different seismic wave velocities
What are the differences between oceanic and continental crust in terms of wave transfer speeds?
Waves travel faster in oceanic crust compared to continental crust due to the mineral makeup of each type. Continental is mostly made from felsic rocks (granite).
The oceanic crust is mostly made of mafic rocks such as basalt.
Waves in the Mantle.
P and S waves pass through the mantle which indicates that it is solid rock only with isolated pockets of magma.
Higher velocities in the mantle indicate higher-density ultramafic composition.
Beneath the lithosphere, seismic wave speed decreases abruptly in the asthenosphere region.
Describe the Geothermal Gradient.
The geothermal gradient highlights the increase in temperature with depth, which is steepest near the surface and tapers off deeper into the Earth due to increasing pressure.
What is the composition of the core?
It is an Iron-Nickel alloy mixed with small amounts of lighter elements.
Describe the P-wave shadow zone.
103 - 142 degrees from the epicenter. It is explained by the refraction of waves. Observation of P-wave refraction indicates that the core is solid.
Describe the S-wave shadow zone
it is ≥103° from epicenter. It suggests that the outer core is a liquid.
