Chapter 19: Earthquakes

Question 1

What are the three types of stress that exist on Earth’s rocks

Answer 1

compression (pushes down), tension(pulls apart), and shear(twists)

Question 2

stress vs. strain

Answer 2

stress=forces per unit area acting on a material

strain=deformation of material in response to stress

Question 3

ductile deformation

Answer 3

maintains deformed even if there is zero strain like an elastic stretched its limit

Question 4

fault

Answer 4

resulting fracture or system of fractures along which movement occurs

Question 5

the 3 types of faults

Answer 5

reverse faults are fractures that form as a result of horizontal compression

Question 6

strike-slip faults

Answer 6

caused by horizontal shear

Question 7

normal faults

Answer 7

fractures caused by horizontal tension

Question 8

primary waves

Answer 8

squeeze and pull rocks in the same direction that the waves are travelling

Question 9

secondary waves

Answer 9

cause rocks to move at right angles in relation to the waves

Question 10

surface waves

Answer 10

move in two directions as they pass through

Question 11

focus vs. epicenter of an earthquake

Answer 11

focus the point where the earthquake originates and epicenter is the point on earth directly above the focus

Question 12

seismometer

Answer 12

detects and records vibrations from Earthquakes

Question 13

seismogram

Answer 13

record produced by a seismometer

Question 14

explain how earthquakes are measured

Answer 14

the Ritcher scale

Question 15

Mercalli scale

Answer 15

rates earthquakes by assesing damage and other effects of an earthquake

Question 16

deep vs. shallow earthquake

Answer 16

deep focus earth quakes produces smaller vibrations at the epicenter than a shallow focus quake. shallow focus has a greater intensity

Question 17

why are three stations needed to find the epicenter of an earthquake

Answer 17

so you can find where the 3 circles overlap at a specific point

Question 18

Where do most major Earthquakes occur

Answer 18

the circum pacific belt because it is on a tectonic boundary