Natural Processes

Question 1

Where and when do earthquakes occur

Answer 1

where- most occur near plate boundaries and also fault lines
when- break in rock mass along which movement has occurred (when plates/rocks move)

Question 2

What is a fault

Answer 2

fractures in the crust along which displacement has taken place and a break in the rock with movement

Question 3

What are the four types of faults and draw a small picture to indicate their movement

Answer 3

1. normal fault ◀️▶️ one going up, one going down
2. reverse fault ▶️◀️
3. strike-slip fault ◀️
   ▶️ side to side
4. dip-slip fault ▶️
   ? up and over

Question 4

what are the three types of seismic waves

Answer 4

1. Primary, or P, waves
2. Secondary, or S, waves
3. Surface waves

Question 5

slowest wave

Answer 5

secondary

Question 6

first wave to arrive at a seismic station

Answer 6

primary

Question 7

most destructive type of wave

Answer 7

surface

Question 8

waves that move side to side

Answer 8

primary

Question 9

waves that move at right angles

Answer 9

secondary

Question 10

waves that have vertical and horizontal displacement

Answer 10

surface

Question 11

fastest types of waves

Answer 11

primary

Question 12

what’s the difference between the focus and the epicenter

Answer 12

focus- place within earth where earthquake waves originate (beneath/below)
epicenter- location on the surface directly above the focus (surface)

Question 13

describe elastic bound

Answer 13

the springing back motion of a former deformed rock and when deformed rock snaps back into place

Question 14

what is an aftershock?

Answer 14

smaller earthquake that follows the main earthquake

Question 15

Define an earthquake

Answer 15

vibration of earth, produced by the rapid release of energy and generates seismic waves that radiate through earth

Question 16

what instrument is used to measure earthquakes

Answer 16

seismograph

Question 17

what is the difference between seismograph and seismogram

Answer 17

seismograph- instrument that measures earthquakes

seismogram- actual reading of seismic waves

Question 18

what is a foreshock

Answer 18

small earthquakes that often precede a major earthquake by days or in some cases, by as much as several years

Question 19

geologists measure the distance between __ and __ wave arrival times to a seismograph

Answer 19

P and S

Question 20

what is the relationship between arrival time and distance to the earthquake epicenter

Answer 20

difference in velocities of P and S waves provides a method for locating the epicenter

• the greater the span of time: further from earthquake
• the smaller the span of time: closer to earthquake

Question 21

how many seismic stations are needed to locate an earthquake

Answer 21

three

Question 22

the process of locating an earthquake is called_______

Answer 22

triangulation

Question 23

what is the name of the scale most commonly used to measure earthquakes

Answer 23

Richter scale

Question 24

the scale goes from ___ to ___

Answer 24

1 to 10

Question 25

at what magnitude is an average earthquake felt

Answer 25

3

Question 26

what is a volcano

Answer 26

a weak spot in the crust where molten material or magma comes to the surface

Question 27

what is viscosity

Answer 27

resistance of a liquid to flowing

Question 28

if lava is highly viscous what is the result

Answer 28

it's sticky and it creates a plug in the volcano which is highly explosive

Question 29

2 examples of high viscosity

Answer 29

syrup and honey

Question 30

2 examples of low viscosity

Answer 30

water and vinegar

Question 31

viscosity of magma in a volcano is dependent on what two characteristics

Answer 31

silica content and temperature

Question 32

what is the relationship between silica and viscosity

Answer 32

- the more silica magma has, the higher its viscosity (sticky and light in color) - the less silica magma has, the lower its viscosity (runny and dark in color)

Question 33

what are the three types of volcanoes

Answer 33

shield volcanoes cinder cone volcanoes composite cone volcanoes

Question 34

define each type of volcano

Answer 34

shield volcano- broad, wide in diameter, slightly domed structure (looks like pancake) and erupts basaltic lava cinder cone volcano- usually small with really steep sides and erupts tephra and cinders composite cone volcano (stratovolcanoes)- large, nearly symmetrical structure, explodes quietly, alternating layers of lava and pyroclastic material and erupts pyroclastic material

Question 35

what is pyroclastic flow

Answer 35

an explosive eruption that hurls out a mixture of hot gases, ash, cinders, bombs, and dust and races down sides

Question 36

what is a lahar

Answer 36

a mudflow that occurs when deposits of volcanic ash and debris become saturated with water and flows down steep volcanic slopes

Question 37

what are the three types of magma and their silica content

Answer 37

basaltic magma- 50% andesitic magma- 60% rhyolitic (felsic) magma- 70%

Question 38

what is silica

Answer 38

an abundant material in the earths crust formed from oxygen and silicon