Question 1

If an S-wave is traveling through rock when it encounters a magma chamber,the S-wave will ________________.

Accepted Answer

S-waves, or secondary waves, cannot travel through liquids, including magma. When they encounter a magma chamber, they are unable to propagate through it.

Question 2

If a P-wave is traveling through sandstone and then encounters peridotite,the P-wave will ________________.

Accepted Answer

B

Question 3

You are studying the seismic data from Mars when you notice that there are no S-waves recorded from 130° through 180° on the opposite side of the planet.What does this information tell you about the interior of Mars?

Accepted Answer

The absence of S-waves in a certain region on the opposite side of the planet suggests that there is a layer of liquid material in the interior of Mars. S-waves are unable to travel through liquids and can only pass through solids. This phenomenon is known as the shadow zone, which occurs when seismic waves are refracted (bent) as they travel through different layers of the Earth or a planet. The presence of this shadow zone indicates the existence of a liquid layer in the interior of Mars.

Question 4

A mountain range made of granite would produce a(n)_____________ gravity anomaly.

Accepted Answer

The answer of A mountain range made of granite would...

Question 5

Which layer of the Earth has the highest density?

Accepted Answer

The inner core is made up of solid iron and nickel with a density that is estimated to be between 12.6 and 13.0 g/cm3, making it the layer with the highest density in the Earth.

Question 6

The core consists of two layers: the ______ inner core and ______ outer core.

Accepted Answer

The inner core is solid and primarily made of iron, while the outer core is liquid and primarily made of nickel and iron. Therefore, option C is the correct choice.

Question 7

Geophysics is the study of _________.

Accepted Answer

Geophysics is primarily concerned with studying the interior of Earth using seismicity (earthquakes), magnetics, and gravity. Choice A is more specific to volcanology, and choice B is related to geology in general. Choice D is more related to geodesy or topography.

Question 8

If a gravity anomaly is negative,what does that imply about the material underground?

Accepted Answer

A negative gravity anomaly indicates that the material underground has a lower density than the surrounding rock. This could be due to the presence of less dense materials such as sedimentary rock, water or air-filled cavities.

Question 9

If a seismic wave is refracted upward at a boundary,what can be said about the material the wave is traveling through?

Accepted Answer

When a seismic wave is refracted upward at a boundary, it means that the wave is moving from a slower material into a faster material. This causes the wave to change its direction of travel and bend upward. This happens because seismic waves travel at different speeds through different types of rocks and minerals, and when they encounter a boundary between materials with different velocities, they can refract or bend.

Question 10

If a P-wave is traveling through the Earth and encounters a molten magma chamber,what will happen to the velocity of the P-wave?

Accepted Answer

When a P-wave encounters a molten magma chamber, its velocity will slow down because the density and elasticity of the molten rock are lower than those of solid rock. As a result, the wave will travel more slowly through the magma chamber, causing a change in its velocity.

Question 11

In the seismic tomography cross section below,where is the subducting Juan de Fuca Plate,considering that the subducting plate is much cooler than the surrounding material?

Accepted Answer

In seismic tomography, cooler material shows up as blue and warmer material shows up as red. The subducting Juan de Fuca Plate is cooler than the surrounding material, so it will show up as a blue blob. The blue blob on the left side of the picture that extends down at an angle into the image (choice B) is the most likely candidate for the subducting plate. The blue blob on the right side (choice A) is likely the result of a different geological feature, and the two red blobs (choices C and D) are warmer materials and therefore not the subducting plate.

Question 12

The picture below shows a seismic tomography image of the western United States.What is the relative temperature of the blue regions (darker grey regions not outlined in black)versus the red regions (darker grey regions outlined in black)?

Accepted Answer

The answer of The picture below shows a seismic tomography...

Question 13

Why would the gravity anomaly over a deep-ocean trench be negative?

Accepted Answer

The gravity anomaly over a deep-ocean trench would be negative because water fills the space above the subducting slab and is much less dense than rock. This creates a deficit in mass and therefore a negative gravity anomaly.

Question 14

What causes the velocity of a P-wave to slow down when it enters the outer core?

Accepted Answer

The answer of What causes the velocity of a P-wave...

Question 15

The following picture is that of a gravity map of the United States.What do the dark grey regions mean in terms of the density of the material below?

Accepted Answer

The dark grey regions on the gravity map indicate areas of higher density material below the surface. These high-density regions are often associated with geological features such as mountain ranges or deep geological formations. Therefore, option A is the most suitable choice.

Question 16

S-waves travel ________ than P-waves; however,unlike P-waves,they _______ travel through liquids.

Accepted Answer

S-waves travel slower than P-waves, but unlike P-waves, they cannot travel through liquids.

Question 17

In the following graph,why does the line for S-waves NOT appear in the outer core?

Accepted Answer

S-waves cannot travel through the outer core because it is liquid. S-waves require a solid medium to propagate, and the outer core is composed of molten iron and nickel. Therefore, the line for S-waves does not appear in the outer core on the graph.

Question 18

Earth's gravity is best represented by an equipotential surface that contains bumps and depressions where areas of more or less gravity appear over the Earth,this representation is called the _________.

Accepted Answer

The equipotential surface that takes into account the variability of gravity over the Earth's surface is called the geoid. The reference geoid is a specific model of the geoid that uses mathematical calculations based on satellite measurements to represent the surface of equal potential energy. Isostasy refers to the balance of forces between the lithosphere and the asthenosphere, while gravitational potential is a measure of the work done in moving an object against gravity.

Question 19

If a ship weighs 52,000 tons and is in isostatic equilibrium when 6,000 tons of cargo is added,what is the total mass of water that will be displaced by the ship after the cargo is added?

Accepted Answer

Isostatic equilibrium means that the weight of the ship is equal to the weight of the water displaced by the ship. Therefore, the weight of water displaced by the ship before the cargo is added is 52,000 tons.

When 6,000 tons of cargo is added, the total weight of the ship becomes 52,000 + 6,000 = 58,000 tons. To maintain isostatic equilibrium, the ship must now displace 58,000 tons of water. Therefore, the total mass of water displaced by the ship after the cargo is added is 58,000 tons.

Question 20

In the picture below,when the ship is filled with cargo it sinks into the water until the mass of water displaced is equal to the mass of the cargo.The ship is then said to be ____________.

Accepted Answer

When a ship is filled with cargo, it sinks into the water until the mass of water displaced is equal to the mass of the cargo. This is known as Archimedes' Principle. In this situation, the ship is said to be in isostatic equilibrium, meaning that it is in a state of balance with the water around it.

Quiz 23: The Earths Interior Revisited: Insights From Geophysics