earthquakes and volcanoes

Question 1

What are earthquakes

Answer 1

Earthquakes are a sudden violent shaking of the ground, as a result of movements within the Earth’s crust or volcanic action

Question 2

What are the causes of earthquakes

Answer 2

Earthquakes are caused by all types of plate boundaries
Sometimes, because of friction, plates try to move and become stuck. Pressure builds up because the plates are still trying to move. When the pressure is released, it sends out huge amounts of energy causing the Earth’s surface to shake violently.

Question 3

What is the focus

Answer 3

The point inside the Earth’s crust where the earthquake originates from is known as the focus.

Question 4

What are seismic waves

Answer 4

The earthquake’s energy is released in seismic waves and they spread out from the focus.

Question 5

what is the epicentre

Answer 5

The seismic waves are most powerful at the epicentre.

The epicentre is the point on the Earth’s surface directly above the focus.

Question 6

What are the factors affecting level of damage earthquake

Answer 6

• Distance from the epicentre - the effects of an earthquake are more severe at its centre.
• The higher on the Richter scale, the more severe the earthquake is.
• Level of development (MEDC or LEDC) - MEDCs are more likely to have the resources and technology for monitoring, prediction and response.
• Population density (rural or urban area). The more densely populated an area, the more likely there are to be deaths and casualties.
• Communication - accessibility for rescue teams.
• Time of day influences whether people are in their homes, at work or travelling. A severe earthquake at rush hour in a densely populated urban area could have devastating effects.
• The time of year and climate will influence survival rates and the rate at which disease can spread.

Question 7

how to measure earthquakes

Answer 7

The power of an earthquake is measured using a seismometer. A seismometer detects the vibrations caused by an earthquake. It plots these vibrations on a seismograph.
We use the Richter Scale to categorize the intensity of different magnitudes

Question 8

What are the 4 types of plate boundaries

Answer 8

Constructive
Destructive
Conservative
Collision

Question 9

What are constructive plate boundaries + characteristics

Answer 9

At constructive boundaries two plates are moving apart. Molten magma rises to the surface, cools and solidifies to form new oceanic crust.
The magma is hot and runny (non viscous) so volcanic eruptions are gentle and non explosive

Question 10

Destructive plate boundaries + characteristics

Answer 10

Destructive boundaries are when dense (heavy) oceanic crust are subducted beneath less dense continental crust.
Intense heat and pressure in the subduction zone creates molten magma which rises to the surface to form explosive volcanoes.
Powerful earthquakes also occur.

Question 11

Conservative plate boundaries + characteristics

Answer 11

At conservative boundaries two plates are grinding slowly past each other horizontally.
There is no volcanic activity but powerful earthquakes occur.

Question 12

Collision plate boundaries + characteristics

Answer 12

Collision margins are where two continental plates collide. The continental crust is too thick to allow subduction.
Instead sedimentary rock is forced upwards to form huge mountain ranges like the Himalayas.
There is no volcanic activity.

Question 13

What are hotspots

Answer 13

Hot spots cause volcanic activity away from plate margins. As the plate moves over the stationary hot spot, a series of volcanoes are formed. The most famous example is the Hawaiian Islands.

Question 14

How are fold mountains formed

Answer 14

by Collison plate boundaries

Question 15

What is the crust

Answer 15

a layer of sand and rock varying from 5-50 km thick

Question 16

What is the mantle

Answer 16

A rock layer about 2850 km thick that reaches about half the distance to the centre of the earth. Parts of this layer become hot enough to liquify and become slow moving molten rock or magma

Question 17

Outer core

Answer 17

a mass of molten iron about 2200 km thick that surrounds the solid inner core

Question 18

Inner core

Answer 18

a mass of iron with a temperature of 3870. Normally iron would melt at this temperature, but its immense pressure keeps it solid. Its 2400 km in diamaeter

Question 19

Process of convection cycle

Answer 19

1. The heat rises off the core and travels through the mantle
2. The heat moves the magma upwards until it hits the bottom of the crust
3. The heated magma spreads sideways below the crust, dragging the plates along
4. The heated magma cools and eventually settles down back to the core
5. The core reheats the magma, continuing the cycle

Question 20

What is oceanic crust

Answer 20

Oceanic crust: younger, heavier, can sink and is constantly being destroyed and replaced

Question 21

What is continental crust

Answer 21

Continental crust: older, lighter, cannot sink and is permanent

Question 22

What are the effects of earthquakes

Answer 22

Large number of deaths
Fires breaking out
Water pipes burst
Water contamination, diseases
Corpses: human & animal
Accessibility difficult
Building damaged/destroyed
Tsunami can follow
Reconstruction costs

Question 23

What are prediction methods for earthquake

Answer 23

• Measure earth tremors, pressure, and release of gas
• Use maps and facts to find pattern in time/location
• Unusual animal behaviour

Question 24

What are preparation methods for earthquakes

Answer 24

-Build earthquake-proof buildings and roads
-Train emergency services
-Set up warning system
Create evacuation plan
Emergency food supply
Practice drills

Question 25

Earthquake proof buildings features

Answer 25

Automated weights on roof to reduce movement

Fire-resistant building material

No bricks or reinforced concrete block

Rubber shock-absorbers between foundations

Foundation sunk deep into bedrock avoiding clay

Roads to provide access by ambulances & fire engines

Open areas where people can assemble if evacuated

Automatic shutters come down over the windows

Interlocking steel frames which can sway during earth movements

Question 26

What are volcanos

Answer 26

A vent in the earth’s surface where magma, gas or ash escapes onto the earth’s surface or into the atmosphere.

Question 27

causes of volcanoes

Answer 27

At constructive margin: plates move away from each other; magma rises to fill the gap;

At destructive margin: oceanic crust melts from friction and heat from mantle; newly formed magma is lighter so it rises to surface

Question 28

advantages of volcanoes

Answer 28

Tourist attraction: income and employment
Creates fertile soil: good agricultural land to grow crops
Geothermal heating: Renewable resource, Heating (hot water), Geyser & mud baths

Question 29

Disadvantages of volcanoes

Answer 29

Destruction of land, property, jobs, homes, transport
Rebuilding costs
Unemployment
Fires breakout
Diseases from poor sanitation
Gas from eruption suffocates
Pyroclastic flow

Question 30

prediction for volcano

Answer 30

Animal behaviour changes

Emits gas & steam

Question 31

When was the monserrat explosion

Answer 31

1995 18 july

25 june 1997

Question 32

Short term response monserrat

Answer 32

Evacuation
Abandonment of the capital city
The British government gave money for compensation and redevelopment

Question 33

Long term response monserrat

Answer 33

An exclusion zone was set up in the volcanic region

A volcanic observatory was built to monitor the volcano

Question 34

short term impacts monserrat

Answer 34

Evacuation of almost 5,000 residents
Delta was created by the flow of lava into the sea
The eruption left the southern two-thirds of the islands completely inhabitable
The following settlements were destroyed : Bethel, Bramble, Dyers, Fairfield, Farm, Farrell’s, Galway’s Estate, Harris, Hermitage, Long Ground, Morris’s, Plymouth, Saint Patrick’s, Tobuscus Mt, Soufrière, Streatham, W. H. Bramble Airport.

Question 35

montserrat long term impacts

Answer 35

The eruption left the southern two-thirds of the islands completely inhabitable.
Pyroclastic flows still pour down the slopes of the volcano.
The eruptions continued after the volcano became active.
The disaster resulted in the collapse of tourism and also the local rice processing industries.
Unemployment shot up from a manageable 7% to over 50%.
Agricultural activities became nearly impossible and living conditions were further worsened by respiratory problems caused by the spewing ash

Question 36

benefits montserrat

Answer 36

Volcano tourism increased
A new delta was formed
More businesses were developed in the north
The airport and several roads had to be rebuilt, resulting in new facilities

Question 37

When was the tohoku japanese earthquake

Answer 37

2011 11 march

Question 38

Short term effects tohoku

Answer 38

Death and injury: roughly 16,000 people died, 6,000 injured and 2,500 people went missing
330,000 buildings, 2000 roads, 56 bridges and 26 railways were destroyed or damaged
300 hospitals were damaged and 111 were totally destroyed
Blackouts for almost 4.4 millions households in japan

Question 39

Long term effects tohoku

Answer 39

Destroyed 46,027 buildings
Cost an estimated $360 billion in damage
Crippled Japan’s nuclear industry
Led to huge trade deficits (A trade deficit occurs when a country’s imports exceed its exports during a given period.) as japan had to import oil after electricity went down after nuclear plants took damage

Question 40

short term response tohoku

Answer 40

Rescue services moved very quickly to the affected areas to clear roads, in order to move the silts and to count the number of deaths
Army helped to provide temporary shelter for the homeless
The Japanese Red Cross received over $1 billion in donations and they gave out over 30,000 emergency relief kits and 14,000 sleeping kits.
The people tried to go back to their normals lives within a few weeks

Question 41

Long term response tohoku

Answer 41

Used 23 trillion yen to rebuild the houses
Replace tsunami barriers with 18m high instead of 12m
Took 1 ½ years for the production of manufacturing companies to begin again (eg) toyota, honda)

Question 42

example of collision plate noundary

Answer 42

indo austrailia plate

Question 43

example of constructive plate boundary

Answer 43

north american plate

Question 44

Example of conservative plate boundary

Answer 44

pacific plate

Question 45

Example of destrutive plate

Answer 45

eurasian plate

Question 46

example of shield volcano

Answer 46

mauna loa hawaii

Question 47

Example of composite volcano

Answer 47

mount fuji japan