Earth's Interior Flashcards
Crust
- Details about layer
- Details about composition
- Thinnest
- Si, Al
- Brittle
very thin, averaging about 30 km thick in the continents and 5 km thick in the oceans
Mantle
- Details about layer
- Details about composition
- 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).
Liquid Outer Core composition
- Fe, Nickel
2300 km thick and is made of a mixture liquid iron (90%) and nickel (10%)
Solid inner Core composition
- Solid Nickel
at the center of the Earth and has a 1200 km radius; it’s made of solid iron (90%) and nickel (10%).
Relationship of Temperature to Pressure
- Increasing temp. = Increasing pressure
How do we know the Earth has layers?
Earthquakes and their seismograph captures waves
Body waves description and examples
- Transmitted into Earth’s interior
- Primary and Shear waves
Surface wave description and examples
- only propagated along Earth’s surface
- destructive
- Complex, Love, Rayleigh
Focus
the point source of energy
epicenter
point on Earth’s surface directly above the focus
Primary waves details
- Faster
-Vibration is parallel to the
propagation - Transmitted in both solid and Liqui
- Arrives FIRST causes a S-P time interval
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?
Nickel and Iron. No it does not since temperature and pressure plays a significant role in this
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?
There is greater pressure in the inner core and this makes it solid
What do scientist study to determine the structure of the Earth?
Scientists study earthquakes and the seismic waves through seismographs
When an earthquake occurs, in what form is energy released?
Seismic waves
How are seismic waves detected?
Through the use of seismograms
How is epicentral distance determined using a seismogram?
When one looks at the S-P interval
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)
Body waves.
How to determine velocity structure of Earth
By measuring travel times of earthquake waves to seismograph stations
In the direct propagation of seismic waves, they generally follow curve paths. Why?
Because of reflection and refraction
Explain the presence of the P wave and S wave shadow zone. Why are they both proof of the existence of liquid outer core?
P waves can propagate in liquid while s waves cannot. This shows that the earth has a liquid outer core
What are discontinuities? Name two of the most important discontinuities.
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.
- What does the low velocity zone represent?
This low velocity zone (LVZ) may be a zone of partial melting of the mantle,
