Restless Earth Flashcards
(107 cards)
1
Q
what are the 4 layers of earth?
A
Crust Mantle outer core inner core
2
Q
what are tectonic plates?
A
sections of the earths crust.
3
Q
how do tectonic plates move?
A
the Earths crust is unstable because the plates are moving due to rising hot currents called convection currents within the mantle. These push and pull the plates.
4
Q
what plate are we on?
A
The Eurasion Plate
5
Q
What are the two types of crust?
A
oceanic continental
6
Q
give two differences between the oceanic and continental crust
A
Continental crust is thicker than the oceanic. Oceanic is under water
7
Q
which countries are most affected by the movement of tectonic plates
A
countries on a plate boundary
8
Q
give another name for a constructive plate boundary
A
Divergent plate boundary
9
Q
what happens at a constructive plate boundary?
A
at a constructive plate boundary, two plates move apart, magma rises up to fill the gap. this causes volcanoes. However, since magma can escape easily at the surface the volcanoes do not erupt with much force.
10
Q
Name an example of a constructive Boundary
A
Mid-Atlantic ridge
11
Q
Give an example of a volcano found at a constructive plate boundary
A
Surtsey, Iceland
12
Q
give another name for a convergent plate boundary
A
Destructive plate boundary
13
Q
What happens at a destructive plate boundary?
A
a destructive plate boundary is found where a continental plate meets an oceanic plate. At a destructive plate boundary the plates are moving together. The denser oceanic crust subducts beneath the lighter continental crust. The oceanic crust sinks into the mantle where it melts in the subduction zone. The energy may be released as an earthquake and the molten magma may rise upwards casing a volcanic eruption. The continental crust becomes fold mountains.
14
Q
What can be found at a constructive plate boundary?
A
Earthquakes and volcnaoes
15
Q
What can be found at destructive plate boundaries?
A
Earthquakes, Volcanoes, deep ocean trenches and fold mountains
16
Q
Give an example of a deep ocean trench
A
Marianas Trench
17
Q
What are the uses of a deep ocean trench?
A
Continental shelf in the ocean can be used for fishing and the drilling of oil and gas.
18
Q
Give another name for a transform plate boundary
A
Conservative plate boundary
19
Q
What happens at a conservative plate boundary?
A
Here the plates slide past each other either in the same or opposite directions. The two plates meet at a boundary and pressure builds up until the two plates suddenly jerk past each other. This causes an earthquake.
20
Q
Give an example of a transform plate boundary
A
The San Andreas Fault, California, USA
21
Q
What can be found at a conservative plate boundary?
A
Only earthquakes
22
Q
What happens at a collisional plate boundary?
A
Collisional plate boundaries occur when two plates of similar densities move together. This causes the material between them to buckle and rise up, forming fold mountains.
23
Q
Give an example of fold mountains and the plates they are found on
A
The Himalayas are an example of chain fold mountains. They have been formed by the Indian plate colliding into the Eurasian plate.
24
Q
Which plate boundary is this?
A
Destructive
25
What plate boundary is this?
Constructive
26
Which plate boundary is this?
Conservative
27
Which plate boundary is this?
Collisionsal
28
What is your fold mountain case study?
The Alps
29
What countries are the Alps in?
France, Switzerland, and Italy
30
How are fold mountains formed?
Where an area of sea separates two plates, sediments settle on the sea floor in depressions called geosynclines. These sediments gradually become compressed into sedimentary rock.
When the two plates move towards each other again, the layers of sedimentary rock on the sea floor become crumpled and folded.
Eventually the sedimentary rock appears above sea level as a range of fold mountains.
31
What are the human activities in the alps?
* Transhumance Farming
* Tourism
* Forestry
* Hydro Electric Power (HEP)
32
What is transhumance farming?
This is a type of dairy farming. It involves people moving the animals to different places depending on the seson. In summer the cows go to the top of the high Alps to graze. Cable cars are used to bring milk to the dairies on the valley floor. The milk is used to make butter and cheese. In winter they buy additional feedstuff so the cows can stay on the valley floor.
33
How do they use forestry in the Alps?
Coniferous trees cover most of the slope, especially the north facing ones. People chop these trees down to get the wood. Wood is the main building material and winter fuel in Alpine lands as there is so much of it. Timber that isn't used for construction is made into pulp and then paper.
34
How do they use tourism in the Alps?
Tourism is one of the main industires in the Alps. The mountains attract people as they can do various sports in winter and summer. In winter people ski and snowboard. In summer people walk, climb, base jump, and paraglide.
35
;+How do they use Hydro Electric Power in the Alps?
The steep slopes, high amount of precipitation, and melting glaciers mean there are fast flowing rivers. These rivers are ideal for generating HEP. Narrow valleys are easy to dam and lakes store water. Its a cheaper power source for the locals. Industries and towns and cities use HEP as a power source.
36
How have people adapted to living in The Alps?
* They have put hairpin bends in the roads so they can easily navigate the steep slopes.
* The have made many parts of roads under tunnels/shelters to protect themselves from avalanches and rockfalls.
* They have put solid road markings to compensate for the poor visability due to fog.
* They have put barries round the high alpine roads so it is harder to drive off.
37
What are the problems wiht long road tunnels under mountains?
* They are expensive.
* They are a fire hazard.
* They take a long time to construct.
38
How are volcanoes formed at a destructive plate boundary? (SEEP)
First the crust moves towards another piece of the crust due to convection currents in the mantle moving the plates. As one crust is subducted beneath another piece of crust, the pressure is increased. As well as pressuer increasing, friction also increases. This means that the temperature of the rock goes up.
As the piece of crust is pushed under the less dense piece of crust it bends and as this happens, a zone of earthquakes is generated. As the oceanic crust subducts under the continental crust it forces the sea bed down with it as well as sea water. This creates deep ocean trenches. As the crust continues down it heats up even more and begins to melt. The melted rock is less dense than the surrounding rock and so rises. As it moves up it breaks through the crust and eventually a volcano froms on the surface.
As times goes on more eruptions happen and the volcano builds up layers of rock. This is repeated for millions of years and so a volcano is formed.
An example of a volcano at a destructive plate boundary is Mt. St. Helens
39
What are the two types of volcano?
Shield
Composite
40
What are the features of a shield volcano?
They from at a constructive plate boundary.
Can occur at hotspots e.g Hawaii.
Gentle sided.
Made from cooled lava.
Do not erupt as violently.
Continuously erupt.
Lava flows freely and far way, up to 25 miles.
Lava is runny, viscous with a low silica content.
E.g Mt. Kilauea, Hawaii, USA
41
What are the features of a composite volcano?
Destructive plate boundary.
Steep sided.
Erupts violently due to pressure building up and being released.
high silica content.
viscous and acidic lava that can't flow far.
Can create a pyroclastic flow
Furthur blockages by rapidly hardening rock allows vents to be blocked.
E.g Mount St. Helens, USA
42
How are hotspot volcanoes formed? (SEEP)
A strong convection current breaks through weaknesses in the crust to begin to from a volcano on the sea floor. Eventually the volcano rises to the surface to srom active, shield volcanoes. As the convection currents cause the plates to move, the volcanic islad becomes extinct becuase it moves off the hotspot. Eventually the island is eroded by the sea and becomes very small. E.g Mt. Kilauea, Hawaii, USA.
43
What are the advantages of living near a volcano?
Fertile soils - Volcanic soils are of a better quality, thanks to the minerals in the ash mixed with the soil. E.g tomoatoes, lemons, oranges, and grape grow very well aroud Vesuvious, Italy.
Tourism
* Historical
* Geothermal activity: Hot springs, mud pools, watching geysers
Power - Geothermal energy.
Valuable minerals - Sulphur, borax, pumice (cosmetic uses)
44
what were the signs that Mt. St. Helens was going to erupt?
Smoke and ash
Newly fromed crater
magmatic activity
bulge growing 1.5m per day
45
what instruments did they use to monitor Mt. St. Helens?
Helicopters
seismomneters/siesmograph
tiltmetres
lasers
robots with cameras and gas detectors
thermal imaging camera
satellite imagery
analysis of rock deposites
46
can you predict earthquakes?
No they are completely unpredictable
47
Can you predict a volcanic eruption?
no
48
How did authorities try to keep deaths low in the Mt. St. Helens eruption?
Set up a red and blue exlusion zones. A coordination centre was set up in Vancouver, Canada to monitor volcanic activity.
49
Who was allowed in the Mt. St Helens red exclusion zone and how big was it?
It had a 11km radious and only state troopers and USGS scientists were allowed in.
50
Who was allowed in the Mt. St. Helens blue exclusion zone and how big was it?
it had a 24km radious and loggers were allowed in
51
Describe the Mt. St. Helens eruption
North face 'slid' down the side then a lateral (sideways) volcanic eruption occur with an associated pyrosclastic cloud. it was triggered by a minor quake. the blast zone was 30km - to north and west of the volcano.
52
What lessons were learnt from Mt. St. Helens ?
US government sends scientists to study what happened at Mt. St. Helens.
USGS realised they made incorrect predictions which more lives were lost than necessary.
53
When was the Mt. St. Helens eruption?
18th may 1980
54
How are volcanoes formed at a destructive plate boundary? (SEEP)
Magma rising from the core due to the convection currents will cause the dense plate (Juan de Fuca) to subduct under the less dense plate (North American). This oceanic crust melts in the magma, causing it to rise through weaknesses in the crust. Pressure builds up inside the earth which when released can cause magma to erupt out of the crust. it then cools to form new crust. after several eruptions the rock builds up and a volcano forms.
55
How are fold mountains formed?
Rivers carry sediment. This sediment accumulates on the sea bed in a geosyncline. The geosyncline then gets filled with sediment which is then compressed into rock by the movement of the plates. This sediment gets forced upward to form fold mountains
56
What is a lahar?
a destructive mudflow on the slopes of a volcano.
57
What is a pyroclastic cloud?
a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing at great speed.
58
What are the primary social effects of Mt St Helens?
57 people killed
Over 100 people injured
59
What are the secondary social effects of Mt St Helens?
People being treated for burns
Long term respiratory problems
Lahar destroyed 200 homes
60
What are the primary environmental effects of Mt St Helens?
eruption created 230km2 blast zone. all signs of life disappeared
Spirit lake was buried by a mud flow
north face 'slid' down the side
Lahars
Scorched landscape
570km2 covered by ash and rock
1/3 of volcano blasted off
61
What are the secondary economic effects of Mt St Helens?
Fishing and forestry jobs were lost
developed tourism
62
what are the secondary enironmental effects of Mt St Helens?
ash fell on nearby cities such as portland
the ash mixed with soil and many years later it made fertile soil
lahar destroyed 27 bridges and 200 houses
63
What are the short term responces of Mt St Helens?
Geologists monitored the volcano for signs it might erupt
A red and blue zone was set up around the volcano to stop people getting too close. Only USGS scientists and state troopers were allowed in the red xone. Only loggers and restricted personel were allowed in the blue zone.
a coordination centre was set up in Vancouver to carefully monitor what the volcano was doing.
looked for survivors after eruption
64
What are the long term responce to Mt St Helens?
lessons were learnt from this eruption and people are now able to predict eruption more accurately
Mt St Helens because one of the most studied volcanoes in the world by vulcanologists
the david johnstone ridge observatory was set up, so people can view the volcano, in memory of the USGS scientist who died in the blast
65
What is a supervolcano?
A supervolcano erupts with a massive volume of material - at least 1000km3 of magma. This is 1000 times bigger than the Mt St Helens eruption. It can alter the landscape for hundreds or even thousands of years. The dust can create a volcanic winter. All the world is affected. The one know to erupt Toba in Indonesia about 75000 years ago.
66
What is the supervolcano case study?
Yellowstone National Park, Wyoming, USA
67
Give 2 features of a supervolcano
Invisible. It is flat and underground so it is hard to see.
Huge magma chamber. some can be 40 miles wide. Yellowstone's is 3x the size of New York City. 5000km3 of magma. 1000km3 needed for super eruption.
68
When has Yellowstone erupted?
2. 1 Million years ago
1. 3 million years ago
640 000 years ago
69
Why are scientists worried about Yellowstone?
Due another eruption in the cycle.
Producing hydrogen sulphide and CO2 which is found in magma.
GPS technology has pointed to ground deformations in the area. Uplift.
Vents in the area were more active, volcanic gases coming out.
Earthquakes higher than 7.0 could trigger an eruption
20 - 25 000km3 magma chamber
70
What is zone 1 in the supereruption?
Name of zone - Pyroclastic zone.
size of impact - 100km radious. 10 000km2 .
Death total - 87 000
Destroy everything in its path
10% chance of survival
71
What is zone 2 in the supereruption?
Name - Ash cloud zone
Size of impact - 1000km radious
Death total - 500 000
Ash causes rooves to collapse, due to weight.
Suffocation from ash.
Transprot affected (air travel)
Damage crops
Destroy power lines
72
What is zone 3 in the supereruption?
Name - sulphur zone
Size of impact - global
Death total - billions
Global cooling caused by extensive suphur gas
15ºC temperature drop in the tropics
Crops would fail = starvation
73
How are major earthquakes caused?
over many years there is a build up of friction and pressure between plates as they try to move past each other. Eventually one plate will suddenly jerk past the other causing an earthquake.
74
What is A
Focus
75
What is B
Epicentre
76
How do you measure an earthquake?
Richter scale - seizmograph
Mercalli scale - people judgement
77
Which plate boundary do eathquakes most commonly occur at?
destructive
78
What are the eathquake case studies?
pakistan 2005
Seattle 2001
79
What were the characteristics of the Pakistan earthquake?
7.6 on Richter scale.
Collision of Indian and Eurasion Plates
Epicentre - Muzzarafabad in the kashmire region of pakistan
80
What are the primary effects of the Pakistan Earthquake?
79 000 people were killed. Final total 100,000
3 million homeless
Landslides and large cracks in the ground
81
What are the secondary effects of the Pakistan earthquake?
Parts of Kashmire still inaccessible today due to landslide on poor mountainous tracks
A severe winter ground operations and led to cholera outbreaks
death toll eventually rose to 100 000
broken sewage pipes contaminated water supplies and spread disease,
People died of cold during harsh winter
82
What were the short term responses to the Pakistan earthquake?
Army and emergency services arrived to join the rescue effort.
Tents were given out by charities.
Aid workers arrived from abroad to find survuves and treat the injured.
83
What were the long term responces to the Pakistan earthquake?
Red cross and red cresent took 2 weeks to send 35 000 tents
$5.2 billion dollars raised in aid
1950's fire engines were donated by england 'rushed' to the scene
schools and hospitals were rebuilt
Building regulations were improved to reduce the damage and the death rate in future earthquakes.
84
What were the poor responses to the Pakistan earthquake?
Hospitals collapsed because they weren't earthquake proof so makeshift tents were uesed instead.
Pakistan refused help of Indian helicopters (Chinook)
Earthquake drills are not done in Kashmire area.
Still living in tents 2 years later
Corrupt port officials stole aid intended for victims
Pakistan had no trained search and rescue teams
Kahmire region is lawless and there is a mistrust of foreigners
poor coordination e.g Norway and UK recuse team sent to same place
Corrupt builders cut corners on construction e.g Margella towers
85
Where is Seattle?
Seattle is located on the west coast of the USA, Washington state, on the ring of fire.
86
What were the characteristics of the Seattle earthquake?
6.8 on the richter scale
Juan de Fuca and North American Plate
87
Name a primary social effect of the Seattle Earthquake
1 woman died from a heart attack
88
Name a primary economic effect of the Seattle Earthquake
Hospital had extensive damage which cost millions of dollars to repair
89
Name a primary environmental effect of the Seattle Earthquake
Quake shattered windows, caused skyscrapers to sway, buckled some roads and railway lines, and led to electricity blackouts
90
How long did it take Seattle to start working normally again?
48 hours
91
Why was the damage so low from the earthquake in Seattle?
the focus was 50km underground
92
What is good about Seattles search and rescue team?
Mobilised quickly to anywhere in the US
Torches to cut through metal
Fibre optic cameras
search dogs
thermal imaging
heavy lifting equipment
93
What are the long term responces to the Seattle earthquake?
Buildings updated to meet the current building regulations
New buildings must be earthquake proof e.g Space needle which can withstand a quake up to 9.1 on the richter scale.
94
How can earthquake danger be reduced? prediction
Monitering movements in the earths crust helps to inform scientists of likely danger.
95
How can earthquake danger be reduced? Preparation
Many households have emergency kits prepared
disaster plans are prepared and regular earthwuake drills are practised each month.
Open areas outside buildings allow pedestrains to assemble if evactuated.
local services are well trained to cope with disaster.
People are educated on what to expect in the event of an earthquake.
International emergency response team essembled and ready to help in under 24 hours.
Hospitals are prepared for treating victims and survivors.
Buildings, roads, and bridges are improved and strenghtened.
Automatic shutters come down over the windows to prevent pedestrians being showered by glass.
Visible identification numbers on rooves help helicopters asses the damage after an earthquake.
Counciling is available for emotionally distressed children.
96
How can earthquake danger be reduced? Protection
New buildings must comply with strict earthquake planning regulations
Evacuation centres are set up in safe areas.
Earthquake proof buildings are safe and protect people rather thean cause danger in an earthquake.
97
What caused the Indian Ocean tsunami?
There is a build up of pressure between 2 plates. Indian plate suddenly subducts under the Eurasion plate as it is more dense. Sea above focus of eathquake is forced upwards. Waves travel up to 500 mph in deep water. Tsunami waves slow down but get higher as they reach land due to added friction from the sea floor.
98
Where was most affected by the Indian Ocean tsunami?
The Indonesian island Sumatra suffered a lot of damage as it was closest to the epicentre.
99
What were the social effects of the Indian Ocean tsunami?
225 000 killed
2 million displaced/homeless
many injured
100
What were the economic effects of the Indian Ocean tsunami?
Fishing industry destroyed on the coast of Indonesia.
Tourist industry affected in Thai resorts on Phuket (e.g Khao Lak) and the island of Koh Phi Phi.
101
What were the environmental effects of the Indian Ocean tsunami?
Infrastructure destroyed - Roads, Rail, Telecommunications.
Coastal areas were particularly affected.
Crops were destroyed by salty sea water coming inland up to 5 miles.
Fresh water supplies contaminated.
102
What are the short term responces to the Indian Ocean tsunami?
Within 1 week £450 million donated
Relief efforts swamped by scale of the damage Chaotic!
Emergency food, fresh water, sheets, and tents poured in from around the world.
Land was flooded so difficult to get around.
Makeshift tents were used to treat injured.
Heavy equipment brought in to clear roads destroyed by force of the water.
It was improtant to get rid of dead bodies to prevent disease.
103
What are the long term responses to the Indian Ocean tsunami?
£7 billion donated:
* Rebuilt homes
* Homes were built stronger and on higher ground.
* Rebuilt fishing and tourist industries
* Rebuilt communications and power.
By 2006:
* An early warning system was put in place e.g tsunami sirens.
* Education programs
104
How does a tsunami early warning system work?
A tsunometre detects a change in pressure and send this information to a buoy which sends it to a satellite.
Buoys detect big waves and send information to satellite.
Satellite sneds information to tsunami alert centre which allerts the population via TV, Phone. and radio.
105
Why did so many people die in the Indian Ocean tsunami?
Many lacked Tv or radio so they didnt get a warning.
Counties look for help overseas so it took a while for help to arrive.
Buildings were poorly built so they collapsed and trapped people.
106
Define Epicentre
The poin on the surface of the earth where the eathquakes greatest force is felt
107
Define Focus
The point directly below the epicentre where the earthquake originates.
