earthquakes

Question 1

Seismologists

Answer 1

study earthquakes

Question 2

Seismographs

Answer 2

are the machines that measure the magnitude, or strength, of an earthquake.

Question 3

Focus

Answer 3

is the place within the crust where an earthquake occurs.

Question 4

Epicentre

Answer 4

is the area on the surface found directly above the focus. It is where the tremors/shock waves reach the surface first. These tremors/seismic waves decrease with distance from the epicentre.

Question 5

earthquake

Answer 5

An earthquake is the shaking or vibration of the Earth’s crust, usually on or near a plate boundary

Question 6

what causes an earthquake

Answer 6

It is caused by the sudden release of energy along a fault line due to the movement of plates caused by convection currents.

Question 7

what happens to the plates during an earthquake

Answer 7

The plates appear to stick, stress and pressure builds up.
When this pressure is suddenly released as the plates slips, an earthquake happens.

Question 8

what are seismic waves also known as

Answer 8

shock waves

Question 9

where do shock waves spread out from

Answer 9

These spread out from the focus deep with the Earth’s crust.

Question 10

what is directly above the focus on earth’s crust

Answer 10

the epicenter

Question 11

what are the waves/tremors that occur after the earthquake are known as

Answer 11

afterschocks

Question 12

where do earthquakes occur

Answer 12

They occur along divergent, convergent and transform plate boundaries

Question 13

what are the most dangerous earthquakes are associated with

Answer 13

Subduction zones, as one plate is dragged beneath another.

Question 14

what subduction zone is most deadly

Answer 14

The subduction zone off the coast of Japan is the most deadly in the world. e.g. Pacific Ring of Fire

Question 15

transform plate boundary earthquake example

Answer 15

San Andreas Fault

Question 16

divergent plate boundary earthquake example

Answer 16

Mid-Atlantic Ridge, but these are not as frequent or dangerous.

Question 17

shallow focus

Answer 17

focus is found close to the surface [less than 80 km from it]

Question 18

what is the most common and dangerous type of earthquake

Answer 18

Shallow focus

Question 19

what do shallow focus earthquakes cause

Answer 19

They cause great loss of life and destruction.

Question 20

where do shallow focus earthquakes occur

Answer 20

Occur at plate boundaries.

Question 21

what are shallow earthquakes results of

Answer 21

It is a result of a plate sinking and becoming stuck and then suddenly releasing its energy.

Question 22

Deep Focus

Answer 22

are found at much deeper depths [greater than 300 km]

Question 23

where are deep focus earthquakes often located

Answer 23

Often located at subduction zones as one plate moves beneath the other.

Question 24

where do deep focus earthquakes occur

Answer 24

They occur so deep in the Earth’s crust that they rarely cause damage on the surface

Question 25

what are seismographs sensitive to?

Answer 25

movement

Question 26

what does a seismograph detect

Answer 26

detects, measures and records the seismic waves that are released by an earthquake.

Question 27

There are three types of seismic waves recorded

Answer 27

Primary or P - Waves Secondary or S - Waves Surface Waves

Question 28

Primary or P-waves

Answer 28

Fastest waves and the first to be recorded Travel through molten material

Question 29

Secondary or S-waves

Answer 29

Slower-moving waves that travel through rock The second to arrive

Question 30

what is the Richter scale used for

Answer 30

Used to measure the ground movement caused by an earthquake and magnitude or strength

Question 31

when was the Richter scale developed

Answer 31

1935

Question 32

by who was the richter scale developed

Answer 32

Charles Richter

Question 33

what does The Mercalli scale messure

Answer 33

Measures the damage caused by an earthquake

Question 34

why is earthquake prediction important

Answer 34

can help prevent loss of life, as people will have enough time to prepare and evacuate.

Question 35

who was the Mercalli scale developed by

Answer 35

Giuseppe Mercalli

Question 36

how many points does the mercalli scale have

Answer 36

12

Question 37

why is it important to know where the most badly affected areas are

Answer 37

so precautions can be put in place in relation to buildings and communication links.

Question 38

how can seismologists predict earthquakes

Answer 38

Seismic Gaps Tiltmeters Radon Gas Lasers Animal Behaviour Level of Water

Question 39

Seismic Gaps

Answer 39

pattern in seismic gaps/length of time between earthquakes in an area

Question 40

Tiltmeters

Answer 40

measure any bulging of the land surface

Question 41

Radon Gas

Answer 41

the levels increase just before an earthquake

Question 42

Lasers

Answer 42

used to monitor vulnerable areas to measure any changed in the ground/rock movement

Question 43

Animal Behaviour

Answer 43

unusual animal behaviour is a sign an earthquake is imminent.

Question 44

Level of Water

Answer 44

it will rise of stress levels in the crust increase prior to an earthquake.

Question 45

LDCs

Answer 45

Less Developed Countries

Question 46

Terrain

Answer 46

The Landscape

Question 47

Geology

Answer 47

The rock type of an area

Question 48

Factors that determine the damage caused by an earthquake

Answer 48

Time of day Magnitude of the earthquake Depth of the focus Distance from the epicentre Duration of shaking Population density in the area Number of earthquake proof buildings Terrain Geology of the area Economic wealth of the region

Question 49

Short-term effects

Answer 49

Loss of life Destruction of buildings and communication links Landslides and avalanches Tsunamis Disruption and damage

Question 50

Long-term effects

Answer 50

Outward migration Disease Economic slowdown

Question 51

Liquefaction

Answer 51

this occurs when unconsolidated material such as sands and gravel mix with water, are shaken vigorously and turned into liquid mud that cannot support structures

Question 52

Outward migration

Answer 52

to leave one area/region in order to settle in another. People migrating from earthquake-prone area leads to homelessness of large numbers of people.

Question 53

Disease

Answer 53

from exposed corpses and damage utilities, as sewage can leak into water supplies

Question 54

Economic slowdown

Answer 54

as shops and industries are damaged.

Question 55

Time of day

Answer 55

people still in bed

Question 56

Magnitude of the earthquake

Answer 56

the stronger the earthquake the more damage caused

Question 57

Depth of the focus

Answer 57

deep focus, less damage shallow focus more damage

Question 58

Distance from the epicentre

Answer 58

the closer the distance the stronger the impact

Question 59

Duration of shaking

Answer 59

the longer an area is shaken, the more damage caused

Question 60

Population density in the area

Answer 60

more people more deaths

Question 61

Number of earthquake proof buildings

Answer 61

more earthquake proof buildings less destruction

Question 62

Terrain

Answer 62

if the landscape is inaccessible, it will be difficult to reach people

Question 63

Geology of the area

Answer 63

if the area is made up of unconsolidated material, it will not take the impact as well as solid rock

Question 64

Economic wealth of the region

Answer 64

ldc's won't be prepared for earthquakes