Earthquakes

Question 1

What is an earthquake

Answer 1

Vibrations or shaking in the earths crust caused by movements at plate boundaries or at fault lines (cracks in the earths surface)

Question 2

Most common boundaries earthquakes occur

Answer 2

Transform

Convergent

Question 3

What is energy released by an earthquake in the form of

Answer 3

Seismic waves that give a series of shocks called tremors

Question 4

Small earthquakes before big earthquake

Answer 4

Foreshock

Question 5

Small earthquakes after big earthquake

Answer 5

After shocks

Question 6

Define focus/ hypocentre

Answer 6

Origin of the earthquake deep within the crust, point where seismic waves radiate outwards from

Question 7

Define epicentre

Answer 7

Point on the earths surface directly above the focus where the most damage occurs

Question 8

Define fault

Answer 8

A break in the rocks that make the earths crust along which rocks on either side move

Question 9

Define Fault scarp

Answer 9

A feature on the surface of the earths that looks like a step caused by a slip in the fault

Question 10

Causes of earthquakes

Answer 10

Slipping plates
Sinking plates
Ice age
Ancient faults

Question 11

Types of earthquakes

Answer 11

Shallow focus
Intermediate focus
Deep focus

Question 12

Where do shallow focus earthquakes occur

Answer 12

All types of plate boundaries
Less than 80km below the surface
Most destructive as closer to surface

Question 13

Where do intermediate focus earthquakes occur?

Answer 13

At oceanic and continental subduction zones

Up to 300km below surface

Question 14

Where do deep focus earthquakes occur

Answer 14

At oceanic and oceanic subduction zones
More than 300km below the surface
Don’t do too much damage to surface as they occur so deep

Question 15

What’s a Wadati-Benioff zone?

Answer 15

Dipping, roughly flat zones of increased earthquake activity as an oceanic plate sinks beneath another plate. (Subduction zones)

Deep focus earthquakes occur here

Question 16

Way of predicting earthquakes

Answer 16

Measuring rock stress
Measuring randon gas emissions 
Observing unusual animal behaviour
Identifying seismic gaps
Early warning systems

Question 17

How can rock stress be measured

Answer 17

Strainmeters (measure build up of stress along fault lines)
Tiltmeters (changes in slope and bulging)
Seismographs (minor movements in earths crust (foreshocks and aftershocks)

Question 18

Examples of unusual animal behaviour before earthquakes

Answer 18

Snakes come out of hibernation
Animals refuse to enter buildings
Restless pets

Question 19

What are seismic gaps

Answer 19

An area on a fault where little to no seismic activity has occurred for a long period eg Guerro Gap Mexico

Question 20

% of earthquakes at Pacific ring of fire

Answer 20

80%

Question 21

Speak about Earthquakes at convergent plate boundaries

Answer 21

Most common
Most intense
Japan 2011- tsunami under ocean (where Pacific and Eurasian collide)
China and India (indo Australian and Eurasian plate collide) recieve Kanu earthquakes

Question 22

Discuss earthquakes at transform plate boundaries

Answer 22

SAN Andreas fault 1300km long
Pacific and North American plate
1906 8.3 earthquake san franc

Question 23

Two scales used to measure earthquakes

Answer 23

Mercalli scale

Richter scale

Question 24

What does the Richter scale measure

Answer 24

Intensity of an earthquake by energy released from the earthquake

Question 25

How is the Richter scale measurements taken

Answer 25

Seismometers One to record primary waves (horizontal shaking) Another to record secondary waves (vertical shaking)

Question 26

How can the epicentre of an earthquake be found by a seismologist

Answer 26

At least three readings are needed from different seismic locations By measuring the time between each recording at the seismic station, seismologists can estimate how far the waves have travelled. They then draw circles representing distance from the station the wave travelled and where their circles intersect is the epicentre

Question 27

Explain the increasing measurements on the Richter scale

Answer 27

Each unit is 10 times more energy than the previous

Question 28

What is the mercalli scale measured with

Answer 28

No instruments | Based on human observation and experience of the effects to people, the natural world and man made structures

Question 29

Measurements on the mercalli scale

Answer 29

Ranges from 1-12 1 being a weak earthquake not felt by humans 5 being a moderate earthquake, a noticeable shake in the ground and 12 being almost complete destruction

Question 30

Factors effecting earthquake damage

Answer 30

Economic development of country - less developed have poor buildings and infrastructure more likely to collapse Population density - urban v rural Time of day - people aren’t on roads at night Rock type - igneous withstand tremors better than sedimentary Depth of focus - shallow v deep focus Energy and duration

Question 31

Ways of reducing the effects of earthquakes

Answer 31

Earthquake drills Efficient urban planning Early warning system Earthquake proof infrastructure

Question 32

What is cross bracing

Answer 32

When frames of buildings are reinforced with steel which joins the building together allowing it to moves as a single unit and not splitting apart

Question 33

Ways of earthquake proofing infrastructure

Answer 33

Cross bracing Deep foundations into solid rock Weights on roof counterbalance shakings Several emergency staircases and exits Shock absorbers in foundations Roof covering area immediately outside building to prevent pedestrian being showered with broken glass Base isolation - bottom section absorbs seismic waves Foundations with flexible springs as shock absorber

Question 34

When was observing animal behaviour used for earthquake prediction

Answer 34

Tianj, China

Question 35

When was japan earthquake/tsunami we study Richter scale How many dead Mention an effect

Answer 35

2011 9 25,000 Fukushima power plant, loss of jobs and slowdown in production , towns shifted

Question 36

When was Nepal earthquake we study Richter scale (magnitude) How many made homeless Mention an effect

Answer 36

``` 2015 7.8 3 million homeless Avalanche - transport systems damaged (providing aid was therefore difficult) Disease in camps ```

Question 37

When was Haiti earthquake we study Richter scale How many dead Mention an effect

Answer 37

2010 7 300,000 dead under rubble €6 billion in aid

Question 38

Japan disaster prevention day

Answer 38

Sept 1

Question 39

Earthquake at transform plate example

Answer 39

1906 | SAN Francisco

Question 40

Big earthquake for San Andreas fault predicted when

Answer 40

2032

Question 41

Example of an earthquake at divergent

Answer 41

Mozambique 2006

Question 42

Example of poor urban planning

Answer 42

2008 Sichuan, China 9000 schoolchildren died whilst buildings around remained intact

Question 43

Example of a building which is earthquake proof

Answer 43

Burj khalifa (worlds tallest building)

Question 44

Example of economic slowdown post earthquake

Answer 44

2004 Christmas tsunami Thailand Fear to travel