Week 3, Chpt 8, 9 Flashcards
(25 cards)
How old is the Earth?
4.5 Billion Years
The oldest ocean crust is ____ years old.
200 million
What kind of seismic wave can travel through both solids and liquids?
P-Wave
What kind of seismic wave can only travel through solids and not liquids?
S-Wave
Do seismic waves move faster or slow in the mantle?
Faster
How can we map out the crust-mantle boundary?
By seeing how fast seismic waves are travelling.
Seismometers can detect earthquakes all around the planet except in
shadow zones.
Why do we have a solid inner core?
Because pressure increases the melting temperature.
How hot is the centre of the Earth?
10, 800 degrees Fahrenheit
How thick is the Earth’s crust?
4000 miles
6400 km
How thick is the Earth’s mantle?
1802 miles
2900 km
How big is the Earth’s core?
760 miles
1220 km
Surface of uniform gravity on Earth
Geoid
Seismic wave velocities generally ____ with depth
increase
Stress of strain causes 3 types of deformation:
Displacement
Rotation
Deformation
How do we calculate strain?
Change in length
_____________
Original length
Strain is controlled by
Temperature
Pressure
Deformation Rate
Composition
Elastic Rebound Theory
Earthquakes happen because of stress build up, causing rock adjacent to the fault to bend elastically until slip on the fault occurs.
Focus Point
The point in the Earth where the slip occurs.
Epicenter
The point on the surface of the Earth directly above the focus point.
Seismic Waves
Earthquake energy travels through rock and sediment in the form of waves.
4 Categories of Seismic Waves(from fastest to slowest moving)
P-wave
S-wave
L-wave (surface wave)
R-wave (surface wave)
An increase in 1 earthquake magnitude number results in
10x increase in shaking and 32x increase in energy release.
Stress causes
strain.
