Online Quiz 2

Question 1

What is the approximate distance from the surface to the center of Earth?

Answer 1

6,400 km

Question 2

The S-wave shadow zone extends from ____ to 180° angular distance from the earthquake focus.

Answer 2

105°

Question 3

The S-wave shadow zone is larger than the P-wave shadow zone.

Answer 3

True

Question 4

Which of the following seismic waves will arrive at a seismograph first?

Answer 4

P wave

Question 5

Which layer in Earth does not transmit S waves?

Answer 5

the outer core

Question 6

Where do P waves travel fastest?

Answer 6

lower mantle

Question 7

Continental crust beneath mountains can be up to ___ kilometers thick.

Answer 7

100

Question 8

How thick is the oceanic crust?

Answer 8

approximately 7 km

Question 9

The oceanic crust consists mostly of

Answer 9

mafic rocks

Question 10

Correctly list the three rock types in order of increasing P-wave velocity?

Answer 10

granite, gabbro, peridotite

Question 11

The Moho marks the top of a partially molten layer

Answer 11

False

Question 12

The crust is denser than the mantle

Answer 12

False

Question 13

Which of the following marks the boundary between the crust and the mantle?

Answer 13

an increase in P-wave velocity and a change in rock type

Question 14

How thick is average lithosphere?

Answer 14

100 km

Question 15

The asthenosphere is stronger than the lithosphere

Answer 15

False

Question 16

The boundary between the mantle and the core lies at a depth of approximately

Answer 16

3,000 km

Question 17

What causes the sharp increases in the velocity of S waves at a depth of 400 and 660 km in the mantle?

Answer 17

changes in the mineral structures

Question 18

At what depth does the transition from the upper mantle to the lower mantle occur?

Answer 18

approximately 400 to 600 kilometers

Question 19

What element makes up most of Earth’s core?

Answer 19

iron

Question 20

The inner core is solid and the outer core is liquid

Answer 20

True

Question 21

Which of the following regions is hottest?

Answer 21

the inner core

Question 22

Seismic wave speeds increase with

Answer 22

increasing density and decreasing temperature

Question 23

Seismic tomography has revealed that seismic waves in the uppermost mantle are relatively

Answer 23

slow beneath mid-ocean ridges and fast beneath subduction zones

Question 24

Where is Earth’s magnetic field generated?

Answer 24

in the outer core

Question 25

Approximately how often does Earth's magnetic field reverse itself?

Answer 25

every 500,000 years

Question 26

Seismic waves that bounce off a boundary between two different materials are said to be ________, whereas seismic waves that cross the boundary and are bent are said to be ________.

Answer 26

reflected; refracted

Question 27

S waves slow down as they travel through the mantle

Answer 27

False

Question 28

The area on the surface of Earth where P waves and S waves are not recorded by seismograms following an earthquake event are referred to as

Answer 28

Shadow zones

Question 29

A P wave that travels from the earthquake focus through the mantle, outer core, back through the mantle, and to Earth's surface is labeled a

Answer 29

PKP wave

Question 30

An S wave that is reflected once off the surface of Earth is labeled an ______ wave.

Answer 30

SS

Question 31

The graphical curve that describes how temperature changes with depth in Earth is called the

Answer 31

geotherm

Question 32

Earth's magnetic field shields the surface of Earth from

Answer 32

solar winds

Question 33

Earth's inner core was discovered by seismologist

Answer 33

Inge Lehmann

Question 34

In a deep mine, temperatures increase at the rate of approximately ______ per kilometer.

Answer 34

25°C