(SEM1Q1, SCI) 2.1 - Interior of the Earth

crust

What layer of the earth is composed of continents, land areas, and ocean floors?

continental, oceanic

What are the two kinds of crusts?

dry land of the Earth's surface

What is the continental crust?

light colored, less dense igneous rocks, metamorphic rocks, and sedimentary rocks

What can you find in the continental crust?

diorite, granite

What are some rocks you can find in the continental crust? (2)

dark, dense igneous rocks

What can you find in the oceanic crust?

gabbro, basalt

What are some rocks you can find in the oceanic crust? (2)

crust and mantle

What two parts of the Earth make up the largest part of mass?

solid iron, magnesium, and silicate rocks

What is the mantle consisted of? (3)

inner core and outer core

What are the two parts of the core?

inner core

What do you call the solid core?

outer core

What do you call the liquid core?

iron and nickel

What elements can you find in the core? (2)

because of the convection in the molten liquid region

Why does the inner core rotate independently?

a region where no direct waves are detected from the focus of an earthquake

What is the core shadow zone?

due to the discontinuity in the core (refraction of P-waves and inability for S-waves to travel through the core)

Why does the core have shadow zones where waves cannot be detected?

failure of S-waves to pass through the outer core; refraction of P-waves

What proves that the core is composed of two layers: liquid outer and solid inner? (2)

mohorovicic discontinuity

What is another way of saying Moho?

Andrija Mohorovicic (1909)

Who discovered the Mohorovicic Discontinuity? When?

boundary between the crust and mantle which has different rocks that transmit waves at different velocities

What is the mohorovicic discontinuity region?

crust

What do you call 1?

mantle

What do you call 2?

outer core

What do you call 3?

inner core

What do you call 4?

vibrations that transmit energy through waves

What does the sudden movement of rocks during an earthquake cause?

outward in concentric spheres at a constant velocity

How do waves radiate in a uniform, homogeneous medium?

the nature of material when they pass through

What do the velocity of the seismic waves depend on?

rigidity, density

What two factors affect the velocity of seismic waves? (2)

refract or reflect

What happens when a seismic wave passes from one material to another?

gases, liquids, solids

Since P-waves are compressional waves, what mediums can it travel through?

solids

Since S-waves are transverse waves, what mediums can it travel through?

it disappears

What happens to an S-wave when it travels through the Earth's surface at angle of more than 103 degrees?

a region where S-waves cannot be detected

What is the S-wave shadow zone?

This is because S-waves cannot pass through liquids. The outer core is liquid so when the S-waves travel from the epicenter to the crust to the mantle, it stops at the outer core because it cannot pass through.

Why can't S-waves be detected beyond 103 degrees?

103 degrees to 143 degrees

At what degree does P-waves disappear from?

a region where P-waves cannot be detected

What is the P-wave shadow zone?

When the P-wave reaches the liquid core, it bends or refracts. This happens because it changes from the solid mantle to a liquid core. It happens again until it reaches outside of the core. The refraction causes areas to not receive any P-waves.

Why do P-waves disappear between 103 degrees and 143 degrees?

Inge Lehmann

Which Danish seismologist and geophysicist discovered that the Earth has a solid inner core and molten outer core in 1936?

measurements of seismic waves were inconsistent (due to the unknown shadow zones at the time)

In the past, seismologists believed the Earth's core was a single molten sphere. However, what was the problem with this idea?