Earthquakes

Question 1

Divergent Boundary

(Constructive Boundary/ Spreading Ridge)

e.g. Iceland

Answer 1

= a plate boundary at which new material is being created

Question 2

Convergent Boundary

(Destructive Boundary)

e.g. off the west coast of South America

Answer 2

= a plate boundary at which material is destroyed at a subduction zone

Explanation = where oceanic crust and continental crust converge, the denser oceanic crust plunges under the lighter, less dense continental crust into the mantle. This is a subduction zone.

Results=

1. island arc - when this happens under the sea instead of under the continent
2. mountains - crumpling of sediment as the plates push together

Question 3

Collision Boundary

e.g where Eurasian and Indian plate collide to form the Himalayas

Answer 3

= a plate boundary in which two similar plates come together - neither is destroyed, but both are folded to form fold mountains

Question 4

Conservative Boundary

(Transform Boundary)

e.g the Sand Andreas fault where the North American plate and Pacific plate move in the same direction but at different speeds.

Answer 4

= a plate boundary in which two similar plates move past each other - neither is destroyed but earthquake activity is common

Question 5

What are the 3 geographical issues associated with earthquakes?

Answer 5

1. impact on human activities
2. human activities increasing the impacts of earthquakes
3. physical factors increasing the impacts of earthquakes

Question 6

What is the epicentre?

Answer 6

the point on the earth’s surface vertically above the focus of an earthquake

Question 7

What is the hypocentre (aka the focus)

Answer 7

the point inside the crust where the earthquake energy is released in seismic waves

Question 8

What does an S wave do?

Answer 8

shake the ground perpendicular to the direction of travel

Question 9

What does a P wave do?

Answer 9

shakes the ground parallel to the direction of travel

Question 10

What are the 2 main types of seismic waves?

Answer 10

1. body waves (s waves and p waves)

2. surface waves (love waves and raleigh waves)

Question 11

Whats the difference between body waves and surface waves?

Answer 11

1. location
   surface waves = restricted to and guided by surface
   WHEREAS
   body waves = can travel through the whole earth
2. place of origin
   surface waves = epicentre
   body waves = focus/ hypocenter

Question 12

What does a love wave do?

Answer 12

create a rolling motion

Question 13

What does a raleigh wave do?

Answer 13

shake the ground at right angles to the direction of movement

Question 14

what type of seismic waves cause most of the damage near the epicentre?

Answer 14

• surface waves (love waves and raleigh waves)

Question 15

What is an earthquake?

Answer 15

a sudden violent shaking of the ground, typically causing great destruction, as a result of movements within the lithosphere or volcanic action

Question 16

What causes an earthquake

Answer 16

• when tectonic plates move alongside each other friction occurs, causing a build up of stress and a deformation of rock
• this stress is stored as elastic energy
• when this stress exceeds the strength of the fault, the rock fractures and rebound to their original positions
• when this happens, seismic waves are released