Earth's Interior

Question 1

Crust
- Details about layer
- Details about composition

Answer 1

• Thinnest
• Si, Al
• Brittle
  very thin, averaging about 30 km thick in the continents and 5 km thick in the oceans

Question 2

Mantle
- Details about layer
- Details about composition

Answer 2

• 80% of the total volume of Earth
• Mg, Fe, Al, Si

2900 km thick (almost halfway to the center of the Earth. It is made of dark, dense, ultramafic rock (peridotite).

Question 3

Liquid Outer Core composition

Answer 3

• Fe, Nickel

2300 km thick and is made of a mixture liquid iron (90%) and nickel (10%)

Question 4

Solid inner Core composition

Answer 4

• Solid Nickel
  at the center of the Earth and has a 1200 km radius; it’s made of solid iron (90%) and nickel (10%).

Question 4

Relationship of Temperature to Pressure

Answer 4

• Increasing temp. = Increasing pressure

Question 5

How do we know the Earth has layers?

Answer 5

Earthquakes and their seismograph captures waves

Question 6

Body waves description and examples

Answer 6

• Transmitted into Earth’s interior
• Primary and Shear waves

Question 7

Surface wave description and examples

Answer 7

• only propagated along Earth’s surface
• destructive
• Complex, Love, Rayleigh

Question 8

Focus

Answer 8

the point source of energy

Question 9

epicenter

Answer 9

point on Earth’s surface directly above the focus

Question 10

Primary waves details

Answer 10

• Faster
  -Vibration is parallel to the
  propagation
• Transmitted in both solid and Liqui
• Arrives FIRST causes a S-P time interval

Question 11

What is the composition of the core? Does this “fit” our previous assumption that the interior of the Earth must be composed of much denser materials?

Answer 11

Nickel and Iron. No it does not since temperature and pressure plays a significant role in this

Question 12

If the inner and outer core are composed mostly of the same material and temperature increases with depth, why is the inner core solid while the outer core is liquid?

Answer 12

There is greater pressure in the inner core and this makes it solid

Question 13

What do scientist study to determine the structure of the Earth?

Answer 13

Scientists study earthquakes and the seismic waves through seismographs

Question 14

When an earthquake occurs, in what form is energy released?

Answer 14

Seismic waves

Question 15

How are seismic waves detected?

Answer 15

Through the use of seismograms

Question 16

How is epicentral distance determined using a seismogram?

Answer 16

When one looks at the S-P interval

Question 17

What type of seismic waves are propagated into the Earth’s interior? How are seismic waves propagated into the Earth’s interior (direct transmission, reflection, refraction)

Answer 17

Body waves.

Question 18

How to determine velocity structure of Earth

Answer 18

By measuring travel times of earthquake waves to seismograph stations

Question 19

In the direct propagation of seismic waves, they generally follow curve paths. Why?

Answer 19

Because of reflection and refraction

Question 20

Explain the presence of the P wave and S wave shadow zone. Why are they both proof of the existence of liquid outer core?

Answer 20

P waves can propagate in liquid while s waves cannot. This shows that the earth has a liquid outer core

Question 21

What are discontinuities? Name two of the most important discontinuities.

Answer 21

All earth layers are separated from each other through a transition zone called discontinuities.

The transition zone between the crust and mantle is called as mohorovicic discontinuity. The mantle –core transition zone is called Gutenberg discontinuity The velocity of P wave decreases and S wave completely disappear at this depth.

Question 22

13. What does the low velocity zone represent?

Answer 22

This low­ velocity zone (LVZ) may be a zone of partial melting of the mantle,