Chapter 17 Flashcards
(37 cards)
What is Geophisics?
The application of physical laws and principles to a study of earth.
What is seismic reflection?
The return of part of the energy of seismic waves to earth’s surface after the waves bounce off a rock boundary.
What is Seismic Refraction?
The bending of seismic waves as they pass from one material to another.
How fast do p waves travel through oceanic crust and what does that indicate about its make up?
about 7 kilometers. It is made up of basalt and Gabbro.
how fast do p waves travel through continental crust?
6 Kilometers per second.
What term do scientist use when referring to continental crust?
felsic
What term do scientist use when referring to oceanic crust?
Mafic.
how thick is continental crust?
30-50 Kilometers.
What is the Mohorovicic discontinuity?
The boundary separating the crust from the mantle beneath it.
What type of rock is the upper mantle made up of?
Ultramafic
where is the low velocity zone?
200 kilometers
What is the S-wave Shadow zone?
The region on Earths surface in which S waves from the earthquake are absent. Usually do to the liquid core.
Do seismic waves speed up or slow down when they go through the athenosphere?
Slow down.
Describe the flow of the core and mantle at eh core mantle boundary.
The dense, heavy portions of the mantle sink to the mantle base, while lighter portions of the core rise to the mantle.
What changes at the core mantle boundery?
- Density
- Seismic Velocity
- Temperature
What is Isostasy?
The balance or equilibrium between adjacent blocks of crust resting on a plastic mantle.
What is isostatic adjustment?
Concept of vertical movement of sections of Earth’s crust to achieve balance or equilibrium.
What is the D Layer?
The transition zone at the base of the mantle where p-wave velocities decrease dramatically is known as the d layer.
Where is the ultra low-velocity zone located?
the undulating border at the core-mantle boundary that results from either temperature or chemical reactions between the mantle and core.
What do the blobs of liquid crystal slush that forms at the mantle core boundary cause?
- Cause changes in the magnetic field
- aid or interfere with core heat loss
- drive mantle convection
- transfer heat to the surface.
What is crustal Rebound?
The rise of Earth’s crust after the removal of glacial ice.
What is a gravity meter?
An instrument that measures the gravitational attraction between earth and a mass within the instrument.
What is positive Gravity Anomaly?
Greater than normal gravitational attraction.
What is a Negative Gravity Anomaly?
Less than normal Gravitational attraction.
