Earthquakes

Question 0

Converge

Answer 0

Collide

Question 1

What are the two types of earthquakes

Answer 1

Caused by volcanic activity

Caused by tectonic plate movement

Question 2

Focus

Answer 2

Where the fault initially ruptures under the ground and the origin of seismic waves

Question 3

Epicentre

Answer 3

Where the seismic waves first reach the surface

Question 4

What are the types of faults

Answer 4

Normal fault
Reverse fault
Strike slip fault
Oblique slip fault

Question 5

A normal fault and eg.

Answer 5

Crust is being pulled apart, the land slumps downwards and away from the block on the other side, eg. Taupo volcanic zone and bay of plenty

Question 6

A reverse fault eg.

Answer 6

When two blocks are driven together/compressed so one side climbs up the sloping fault and overlaps the other. Eg. South Island and lower north island

Question 7

Strike slip fault and eg.

Answer 7

Blocks move sideways past each other. Sinistral when far side moves left and dextral when far side moves right eg. many major faults in New Zealand

Question 8

Oblique slip fault and eg.

Answer 8

Different movements are combined. Eg. Wairarapa fault caused 1855 earthquake with reverse and strike slip movement

Question 9

Deep earthquakes

Answer 9

Only occur when a tectonic plate subducts deeply into the mantle

Question 10

Shallow earthquakes

Answer 10

Occur along tectonic plate boundary caused by beginning of subduction of oceanic crust

Question 11

Two main types of waves

Answer 11

Body waves and surface waves

Question 12

Two types of body waves

Answer 12

P wave

S wave

Question 13

Two types of surface waves

Answer 13

Love wave

Rayleigh wave

Question 14

Primary waves

Answer 14

Travel through the earth
Fastest, arriving at seismometer first. Moves rock particles backwards and forwards in the direction the wave is travelling

Question 15

Secondary waves

Answer 15

Move more slowly arriving second Result in a rolling motion
Travel through earth
Move rocks particles perpendicular to the path of the waves

Question 16

Love and Rayleigh waves

Answer 16

Arrive last
Being near surface and MIRV along surface only
Destructive waves because most intense

Question 17

The two scales for measuring earthquakes

Answer 17

Richter scale

Mercalli scale

Question 18

Richter scale

Answer 18

Compares earthquake magnitudes or the amount of energy released of an earthquake

Question 19

Mercalli scale

Answer 19

Measures earthquake shaking by its effects on people, buildings and the environment

Question 20

Volcanic earthquakes

Answer 20

Magma and volcanic gases moving up towards the surface can break the surrounding rock, producing moderate volcanic earthquakes, tremors and ground swelling

Question 21

Why are earthquakes caused by tectonic plate movement frequent

Answer 21

Because nz straddles he AP/PP tectonic plate boundary

Question 22

How are faults formed?

Answer 22

When tectonic plates converge or move laterally past each other, the crust slowly distorts and stress builds up over many years. the stress is released by the crust cracking, forming faults and therefore causing earthquakes

Question 23

The strength of an earthquake depends on what?

Answer 23

how much of the fault has shifted
the depth of an earthquake
the amount of elastic potential energy that has built up over time

Question 24

Major historical earthquakes

Answer 24

Murchison 1929 - white creek fault Napier 1931 Darfield 2010 -greendale fault Wairapara 1855 which caused 3 different types of tsunamis

Question 25

What is liquefaction

Answer 25

Causes the strength and stiffness of a soil to be reduced by earthquake shaking squeezing out water. The soil flows as a liquid instead.

Question 26

Subduction earthquakes

Answer 26

Occur when one plate subducts under another, friction stops the subducting plate sliding smoothly. Pulls the overlying plate causing shallow earthquakes (accretionary wedge)

Question 27

How are earthquakes recorded

Answer 27

By a network of seismometers

Question 28

What are seismometers

Answer 28

Measure movement of the ground at that particular place

Question 29

What is amplitude

Answer 29

Measures the energy of the waves

Question 30

Major faults in nz

Answer 30

North Island fault system -cook strait to bay of plenty Marlborough fault system - marlborough coast to alpine fault Alpine fault - cook strait to milford sound

Question 31

north island fault system

Answer 31

``` waiohau whakatane waimana wairarapa wellington ruahine mohaka ```

Question 32

Marlborough fault system

Answer 32

hope clarence awatere wairau

Question 33

example of subduction earthquake

Answer 33

Fiordland earthquake 2009

Question 34

When is a fault considered active

Answer 34

if it has moved within the last 100,000 years

Question 35

What is the reoccurrence interval for earthquakes on faults

Answer 35

The average time between earthquakes on any given fault

Question 36

What is the fault called that caused the murchison earthquake

Answer 36

white creek fault

Question 37

What is the fault called that caused the darfield earthquake

Answer 37

greendale fault

Question 38

What are faults

Answer 38

cracks made in the crust due to stress being built up over time but is then released

Question 39

Example of liquefaction

Answer 39

As Christchurch is built on river and swamp sediments the particles of the sediment are often small in size with not much strength. strong shaking from an earthquake cause water pressure to increase and soil particles to move to each other. Therefore causing liquefaction. Soil can no longer support buildings, sewerage or water pipes so they become badly damaged

Question 40

how does the geosphere cause earthquakes

Answer 40

there is movement along faults that run through rock

Question 41

how does the hydrosphere cause earthquakes

Answer 41

offshore earthquakes cause tsunamis, water between layers of rock increases the chance of landslips after an earthquake. liquefaction occurs only with the right combination of water and water-laden silt

Question 42

how does the biosphere cause earthquakes

Answer 42

a hillside well covered in vegetation is les likely to slip after an earthquake thn one that has been stripped of vegetation

Question 43

accretionary wedge and eg.

Answer 43

crumpled and uplifter sediments at the subduction zone due to a subducting plate eg. napier

Question 44

how does an accretionary wedge cause an earthquake

Answer 44

the wedge contains many faults and movement of one of these with the assistance of the continental subduction pacific plate downwards causes movement along the fault therefore an earthquake