Chapter 5

Question 1

Define: Earthquake

Answer 1

Earth shaking caused by rapid release of energy

Question 2

Define: Focus (hypocenter)

Answer 2

The place where the fault slip occurs

Question 3

Define: Epicenter

Answer 3

point on surface directly above the faults

Question 4

Define: Fault

Answer 4

Fracture surface separating blocks of rock that have moved relative to one another

Question 5

The blocks on a dipping fault are classified as the ____________ and the _____________________.

Answer 5

hanging wall
Footwall

Question 6

In a normal fault in the crust, the hanging wall moves ________________ relative to the footwall.

Answer 6

down

Question 7

A normal wall results from what kind of stress?

Answer 7

pull-apart or stretching (tension)

Question 8

In a reverse fault, the hanging-wall moves _____________ relative to the footwall.

Answer 8

Up

Question 9

A reverse fault results from what kind of stress?

Answer 9

Compression (squeezing or shortening)

Question 10

In a strike-slip fault, one block slides past the other block while maintaining a relatively flat surface. What stress is this this the result of?

Answer 10

Shearing

Question 11

Seismic waves are vibrational waves that travel via solid earth materials outward in all directions from the FOCUS. Name the 2 main groups of seismic waves.

Answer 11

1. Body waves
2. Surface waves

Question 12

Define: body waves

Answer 12

Fastest waves that travel through the body of the earth

Question 13

Define: Surface waves

Answer 13

Slower waves that travel along the earth’s surface, most destructive type of seismic waves

Question 14

What two types of body waves are there?
Which one is the fastest?

Answer 14

1. P-waves (fastest)
2. S-waves

Question 15

S-waves (secondary or shear waves) only travel through ______________.

Answer 15

Solids

Question 16

What 2 type of surface waves are there?

Answer 16

1. Love waves
2. Rayleigh waves

Question 17

What is a seismometer?

Answer 17

An instrument that an measure ground motion.

Question 18

What 2 measurements describe earthquake size?

Answer 18

1. Intensity: severity of damage
2. Magnitude: amount of energy released by the earthquake

Question 19

What does the Mercalli Scale measure?

Answer 19

Intensity

Question 20

What is the magnitude of an earthquake?

Answer 20

QUANTITATIVE measurement of amount of energy released by an earthquake

Question 21

Is the logarithmic richter scaled still in use today?

Answer 21

No

Question 22

What is the most accurate measurement of the magnitude of an earthquake today?

Answer 22

Moment Scale

Question 23

Intermediate and deep earthquakes only occur at what type of plate boundaries?

Answer 23

Convergent

Question 24

True or False: The shearing San Andres fault is a very active strike-slip fault.

Answer 24

True

Question 25

What likely cause are there for Intraplate Earthquakes?

Answer 25

Remnant crustal weaknesses in the former fault ones or ancient plate boundaries

Question 26

Name 2 human activities that can cause earthquakes?

Answer 26

1. Deep waste disposal
2. Nuclear bomb/explosions

Question 27

How do p-waves and s-waves cause earthquake damage?

Answer 27

P-waves: first to arrive, produce a rapid, buckling up and down motion
S-waves: arrive second, produce a pronounced back and forth motion

Question 28

How do love waves and rayleigh waves affect earthquake damage?

Answer 28

Love waves: arrive soon after s-waves and cause ground to writhe like a snake
Rayleigh Waves: last to arrive and cause land surface to undulate like ripples across a pond. Theses waes usually last longer than the others.

Question 29

Which of the 4 types of seismic waves cause the most damage?

Answer 29

Rayleigh waves