Tectonics Flashcards
1
Q
What is oceanic crust?
A
Thinner and denser than continental plates.
2
Q
What are tectonic hazards at plate boundaries called?
A
Interplate.
3
Q
What are tectonic hazards in the middle of a plate called?
A
Intraplate.
4
Q
What is the rock type of oceanic crust?
A
Basaltic.
5
Q
What is the rock type of continental crust?
A
Granite.
6
Q
What type of plate boundaries is the Pacific Ring of Fire associated with?
A
Destructive.
7
Q
What are the two types of convergent plate boundaries?
A
Destructive (oceanic and continental) and collision (two continental).
8
Q
What happens at destructive (convergent) plate boundaries?
A
- Plates move towards each other.
- Denser oceanic plate sinks into the asthenosphere and melts.
- This forms deep ocean trenches or fold mountains as the continental plate is pushed up.
9
Q
How are volcanoes formed at destructive (convergent) plate boundaries?
A
Magma created by melting oceanic plate in asthenosphere rises through faults in continental crust.
10
Q
What happens when two destructive (convergent) oceanic plates meet?
A
- Faster and denser/older plate sinks and melts in asthenosphere.
- Rises up through Benioff zone.
- Forms underwater volcanoes and island arcs.
11
Q
What happens in earthquakes when destructive (convergent) oceanic-oceanic plates meet?
A
- Friction and build-up of pressure is created.
- Subducted under as rock fractures.
- Happens in Benioff zone.
12
Q
What can happen when oceanic-continental destructive (convergent) plates meet?
A
- Friction/pressure built.
- Rock fractures and subduction of oceanic plate.
- Can trigger tsunamis.
13
Q
What type of plate boundaries trigger tsunamis?
A
Destructive (convergent), normally oceanic and continental.
14
Q
Where do earthquakes occur in two oceanic destructive (convergent) plate boundaries?
A
Benioff zone.
15
Q
What happens in collision (convergent) plate boundaries?
A
- Neither plate subducted as both are the same density and less dense than the asthenosphere.
- Forms high fold mountains.
16
Q
Do you get volcanoes at collision (convergent) two continental plate boundaries?
A
No, as no plate subducted into asthenosphere to melt into magma.
17
Q
How do earthquakes form at collision (convergent) plate boundaries?
A
- Sediments are crumpled and compressed so much that one plate becomes denser and pressure and friction builds up.
- Until one plate gets subducted into asthenosphere.
18
Q
What type of earthquakes do convergent plate boundaries form?
A
Shallow focus.
19
Q
What are the two names for when two plates move away from each other?
A
Constructive or divergent.
20
Q
What happens at constructive/divergent plate boundaries?
A
- If on land, as plates move apart, this stretches the crust.
- Crust collapses into parallel sets of faults and forms steep-sided rift valleys.
- New crust is formed from hot magma rising from asthenosphere and cooling.
- If in ocean, forms mid-ocean ridges such as the Mid-Atlantic Ridge.
- Transform faults cut across the ridges and separate them.
- This releases pressure on asthenosphere and it melts so new magma rises.
21
Q
How are volcanoes formed along constructive/divergent plate boundaries?
A
Submarine volcanoes along mid-ocean ridges create islands.
22
Q
How do earthquakes occur on constructive or divergent plate boundaries?
A
Rock goes apart, causing movement that results in shallow earthquakes.
23
Q
What happens at conservative plate boundaries?
A
- Two plates slide side to side, causing friction and pressure that eventually breaks and results in a major break in land called a transform fault.
24
Q
Do volcanic eruptions occur at conservative plates?
A
No, as no crust is created or destroyed.
25
How do earthquakes occur at conservative plate boundaries?
- Friction and pressure builds as rock sticks together.
- Suddenly slips and fractures, releasing strong powerful shallow focus earthquakes.
26
What are the four theories for tectonic movements?
Mantle convection, subduction, slab pull, sea floor spreading.
27
How does a volcanic hotspot occur?
- Located in areas of lithosphere above mantle plumes where magma is extra hot.
- If this is a thin section of lithosphere, the magma can break through the plate.
- As the lithosphere plate moves, it creates a chain of volcanoes.
28
Example of a hotspot volcano eruption with magnitude?
Kilauea on the southeast of Big Island, Hawaii 2018, 5.2 on MMS.
29
Hazards from Kilauea eruption 2018?
- Weak ash plumes of 10km.
- Lava flow of 100m³ per sec in the Lower East Rift Zone.
30
Short term impacts of Kilauea eruption?
- 2500 evacuated.
- No deaths due to good scientific monitoring and little danger in lava flows.
- Lava covered almost 60 road miles.
- 700 houses destroyed.
31
Long term impacts of Kilauea eruption 2018?
- 20 kilotons of high sulfur smog a day giving respiratory problems.
- Most of Hawaii Volcanoes National Park closed in 2018, reducing tourism as normally 2 million visitors, reducing jobs.
32
How does an intraplate earthquake occur?
- Zones of weaknesses in plates due to spherical surfaces causing areas of pressure and stress.
- They might even occur along ancient rift valleys or fault lines reactivated by tectonic stress.
33
Example of an intraplate earthquake?
Kent, UK 2007.
34
Kent earthquake magnitude and deaths?
4.2 MMS, 0.
35
What is a volcano?
A landform that erupts lava, formed by magma rising through a fissure in Earth's crust.
36
What is the scale that measures volcanic activity?
Volcanic Explosivity Index (VEI) - measuring volume, height, and duration of eruption.
37
What magnitude has there never been a volcanic eruption above?
8.
38
What type of volcanoes occur at divergent (constructive) plate boundaries?
Effusive eruptions with shield volcanoes.
39
What type of lava is associated with effusive eruptions?
Basaltic lava, which is very hot (up to 1200°C), low gas content (0.5-2%), and low silica content (50%).
40
How is basaltic lava formed?
Melting of mantle minerals.
41
What is dangerous about basaltic lava?
If it hits ice, it can cause more explosive eruptions due to water vapor bubbles trapped and higher pressure.
42
What type of volcanoes and eruptions occur at convergent/destructive plate boundaries?
Explosive eruptions from stratovolcanoes.
43
What type of lava do explosive eruptions often have?
Andesitic and rhyolitic (most dangerous).
44
What are the characteristics of rhyolitic and andesitic lava?
- Cooler (650-1000°C).
- Less pressure.
- Higher gas content (3-6%).
- Higher silica content (60-70%).
45
What do the characteristics of andesitic and rhyolitic lava mean?
There is a higher viscosity and more pressure as there is a higher content of gas bubbles, which gets trapped and explodes more violently.
46
What type of eruptions and volcanoes does rhyolitic lava form?
Cataclysmic eruptions and supervolcanoes.
47
What type of eruptions cause pyroclastic flows?
Explosive eruptions.
48
What are six volcanic hazards?
Jokulhlaup, pyroclastic flows, lava, tephra, volcanic gas, lahars.
49
What is a jokulhlaup?
Glacial outburst flood carrying glacial moraines and ice blocks from when a volcano erupts under ice.
50
What is a pyroclastic flow?
Extremely fast (up to 700 km/h) and hot (up to 1000°C) moving ash (cloud), rock (tephra), and gas that moves down the side of a volcano.
51
What is tephra?
Solid and molten rock fragments and (ash) particles ejected into air by a volcanic eruption.
52
Examples of volcanic gases and their effects?
- Water vapor = leads to heavy rainfall events and possible lahars.
- Sulfur dioxide = particles carried into stratosphere and reflect sun's radiation, cooling Earth. Can also combine with water to form acid rain.
- Carbon dioxide in small amounts increases global warming.
53
What is a lahar?
Water mixed with volcanic deposits flowing fast into valleys. Causes include heavy rainfall from water vapor emitted and melting snow or ice from eruption at high altitude.
54
Causes of Montserrat eruption?
Destructive plate boundary of South American and Caribbean plate. Subduction of South American plate due to convection currents.
55
What type of eruption was Montserrat?
Explosive with pyroclastic flows, as it was on a destructive plate boundary.
56
What was the magnitude of Montserrat?
VEI 3.
57
Hazard of Montserrat?
Pyroclastic flow with tons of hot (400°C) rock/boulders and clouds and lava racing down mountainside at 100 mph.
58
Short term impacts of Montserrat eruption?
- 19 people killed by pyroclastic flow (disobeyed evacuation orders) destroying 2/3rds of the island.
- 5000 people displaced due to exclusion zone in the south of the island.
59
Long term impacts of Montserrat?
- Unemployment rose from 7% to 50%.
- 70% rise in rent for accommodation.
60
Management of Montserrat before eruption?
- British and American scientists set up Montserrat Volcanic Observatory using instruments such as COSPEC to measure sulfur dioxide emissions.
- Created exclusion zone of 2/3rds of the island
61
Management of Montserrat after the eruption?
- Gave everyone £725 that got moved.
- Started redevelopment improving housing and water supplies funded by £75 million.
62
GDP of Montserrat in the Caribbean?
13,500 - developing country.
63
GDP of Iceland eruption 2010?
68,400 - HIC.
64
Causes of Iceland eruption 2010?
Divergent/constructive plate between Eurasian and North American.
65
What type of eruption was Iceland 2010?
Effusive.
66
Hazards of Iceland 2010 eruption?
- Ash cloud 9 km into atmosphere.
- Flooding/jokulhlaup from glacier.
- Lava flows.
- Sulfur dioxide.
67
Immediate impacts of Iceland eruption 2010?
- Flooded roads and towns.
- 10 cm ash on farmland.
68
Long term impacts of Iceland 2010 eruption?
- Over 20 countries closed airspace due to ash being abrasive to engines.
- Losing £1.6 billion to airline industries.
69
Management of Iceland before eruption 2010?
Monitoring seismic activity and ground deformations.
70
Management of Iceland after eruption?
- 8000 evacuated and flight ban.
71
Magnitude of Iceland 2010 eruption?
VEI 4.
72
DRC Mount Nyiragongo eruption 2002 cause?
Divergent/constructive African, Nubian, and Somali plate.
73
DRC 2002 type of eruption?
Composite volcano with basaltic lava, not explosive, not like normal.
74
Hazards of DRC 2002 eruption?
- Lava flows.
- Earthquakes.
- Volcanic gases like CO2.
75
Primary impacts of DRC volcano 2002?
- 12,500 homes destroyed.
- Lava covered 1/3 of Goma city including 80% of international airport.
- 147 died.
76
Secondary impacts of DRC eruption 2002?
- 120,000 homeless in Goma.
- Cholera at refugee camps.
- Looting in Goma.
77
Management of DRC 2002 eruption?
- 400,000 evacuated but slow as only began when plumes spotted due to governance response to monitoring systems by the USGS (they had 5 monitoring units but the gov didn't listen)
- Because of this, 50,000 people stuck in Goma between lava flows.
- UN sent 260 tonnes of food.
- Oxfam sent 35 tonnes of water cleaning equipment.
78
Three examples of volcanic eruptions and when?
- Montserrat, Soufriere Hills 1997.
- Iceland 2010.
- Mount Nyiragongo, Democratic Republic of Congo 2002.
79
GDP of DRC?
580 - LIC.
80
What is mitigation?
Avoiding, delaying, or preventing hazard events.
81
What is adaptation?
Reducing the impacts of hazard events.
82
What are the four stages of the hazard management cycle?
Mitigation/prevention, preparation, response, recovery.
83
What three ways can disasters be managed by modifying impacts?
Modifying the event (tsunami defenses), modifying vulnerability (education), modifying loss (aid).
84
Three mitigation strategies for volcanoes?
Land use zoning/hazard mapping, diverting lava flows, hazard-resistant design and engineering defenses.
85
Example of land use zoning for volcanoes?
Montserrat eruption, 2/3rds of the island was in an exclusion zone which meant 8000 people were evacuated.
86
Example of diverting lava flows for volcanoes?
Heimaey Island, Iceland 1973, used ocean water diverted to solidify lava before it reached the port.
87
Example of hazard-resistant design and engineering defenses for volcanoes?
Triple roof support with steep slopes over 45 degrees. ash is 2x heavier when it rains and is wet too and there is often water vapour causing rain.
88
Four examples of adaptation strategies to volcanoes?
High tech monitoring and forecasting to predict hazards, modeling hazard impacts, public education, community preparedness.
89
Example of high tech monitoring and forecasting to predict volcanic hazards?
Montserrat Volcanic Observatory used COSPEC tech to measure gas emissions to indicate eruptions. at the max there were 4000 tonnes of sulfur gas a day
90
Example of modeling hazard impacts for volcanoes?
Iceland 2010 eruption, the Numerical Atmospheric Dispersion Modeling Environment (NAME) used computers to create an ash dispersal model. this had history dating back to 1957
91
Example of public education for volcanoes?
USGS made a hazard program with an essential checklist for safety during a volcanic eruption.
92
Community preparedness example for volcanoes?
Indonesia has millions of communities that are isolated and have their own early warning systems.
93
What earthquake scale is no longer used?
Richter scale.
94
What two earthquake scales are used now?
Moment magnitude scale (MMS) and Mercalli scale.
95
What is the MMS?
Measures the energy released during an earthquake related to the amount of movement at the fault slip area.
96
What is the Mercalli scale?
Measures what people feel during the earthquakes and the intensity of the effects of the shaking on a scale of 1-7.
97
What is a better earthquake measure?
MMS because the Mercalli scale is dependent on building structure, GDP, etc.
98
What are the two general types of seismic waves?
Body waves (travel in the body of the earth) and surface waves (travel along the earth's surface).
99
What are the differences between body and surface waves?
Surface waves are slower moving but generally more destructive.
100
What are the two types of body waves?
Primary waves and secondary waves.
101
What are two types of primary earthquake hazards?
Ground shaking (caused by surface waves) and crustal fracturing (crack in crust).
102
What is the Mercalli scale dependent on?
The Mercalli scale is dependent on building structure and ground properties.
103
What are the two general types of seismic waves?
Body waves (travel in the body of the Earth) and surface waves (travel along the Earth's surface).
104
What are the two types of primary earthquake hazards?
Ground shaking (caused by surface waves) and crustal fracturing (crack in the crust).
105
What are the three types of secondary earthquake hazards?
Mass movement, liquefaction, and tsunamis.
106
What conditions are required for mass movement?
Needs steep-sided slopes and can cause landslides, rockfalls, and avalanches. this occurs when the shaking in thr ground reduces the internal strength of the slope increasing the pressure on it and creating a slip plane
107
What is an example of mass movement due to an earthquake?
The Sichuan China 2004 earthquake had 45,000 landslides.
108
What is liquefaction and what does it require?
Liquefaction requires high water content and loosely packed soil or sand, causing sediments to lose strength in response to strong ground shaking. often this can cause buildings to sink
109
What is an example of liquefaction due to an earthquake?
Mexico City 1985.
110
What is the definition of a tsunami?
A large seismic sea wave generated in an ocean by a disturbance such as an earthquake, landslide, or volcanic eruption.
111
What are four case studies for earthquakes and tsunamis?
Japanese 2011 earthquake and tsunami, Boxing Day (Asia) tsunami and earthquake 2004, Haiti earthquake 2004, Sichuan earthquake China 2008.
112
What is the GDP of Japan?
$39,300 per capita (developed country).
113
What are the causes and plate boundary for the Japanese tsunami and earthquake 2011?
Pacific plate and Eurasian plate (destructive margin).
114
What was the magnitude, location of the epicenter, and focus depth of the Japan 2011 earthquake?
- Magnitude: 9 on the moment magnitude scale
- Location: 100km off the coast (east of Sendai)
- Focus depth: 24.4km below the surface.
115
What are five statistics about the hazards of the Japan earthquake/tsunami 2011?
- 7m wave traveling at 500mph which took 10 minutes to reach the coast of Japan.
- The wave was 40m in some places.
- Water flowed 10km into the island, destroying Sendai island.
116
What were the short-term impacts of the Japan earthquake/tsunami?
- 25,000 dead (65% were 60 or older).
- Costed $300 billion.
117
What were the long-term impacts and management of the Japan earthquake/tsunami 2011?
Fukushima nuclear power plant damaged by water, leading to 200,000 people evacuated 20km radius away due to radioactivity. even in Tokyo (220km away) the radioactivity was too high
118
What were four management strategies for the Japan tsunami 2011?
- PTWS (Pacific Tsunami Warning System) TV warnings and text warnings.
- 70,000 temporary homes occupied.
- Fukushima plant evacuation of 200,000 people.
- British donations via the Red Cross.
119
What was one management strategy for the Japan earthquake 2011?
After 10 days, 452,000 people were living in evacuation facilities.
120
What was the magnitude, type of plate boundary, and focus of the Boxing Day tsunami/earthquake?
- Magnitude: 9.4 on the moment magnitude scale.
- Type of plate boundary: Destructive plate boundary of India plate being subducted beneath the Burma plate.
- Focus: 18km below the surface.
121
What type of earthquake was the Boxing Day 2004 event?
Megathrust earthquake.
122
How high was the Boxing Day tsunami wave and how fast did it move?
15m wave at coasts traveling at 500mph.
123
What is a drawback with tsunamis?
When water gets drawn back on the beach before the tsunami wave hits.
124
How many countries suffered loss of life and what was the death toll of the Boxing Day earthquake/tsunami?
11 countries, 225,000 deaths.
125
What was the major problem with the Boxing Day tsunami?
There were no warning systems in place, leading to a major death toll.
126
What was the estimated cost of the Boxing Day earthquake/tsunami?
$14 billion.
127
What is the GDP of Haiti?
$1,800 - LIC or developing country.
128
What are the plate boundary, magnitude, focus, epicenter location, and hazards of the Haiti earthquake 2004?
- Conservative plate boundary.
- Magnitude: 7 on the moment magnitude scale.
- Epicenter: 24km from capital Port-au-Prince.
- Focus: 13km deep.
- Hazards: Ground shaking and collapsing buildings.
129
What were two statistics about Haiti's living conditions before the earthquake?
- 39% had access to safe water.
- 24% had access to sanitation.
130
How highly populated was Port-au-Prince before the Haiti 2004 earthquake and what did this mean?
2 million people, leading to a high rate of urbanization and slum buildings.
131
What was the fraction of people that were unemployed before the Haiti earthquake 2004?
2/3rds.
132
What was the state of the infrastructure of Haiti before the 2004 earthquake and why?
Poor due to high levels of corruption in the government, leading to many buildings being built illegally with no housing codes
133
What were three immediate impacts of the Haiti earthquake 2004?
- 15% in the capital either died or were injured.
- Over 200,000 died.
- 1/3rd of buildings collapsed in the capital.
134
What were the secondary effects of the Haiti earthquake 2004?
Cholera hit the camps set up after the earthquake, leading to over 6,000 deaths.
135
What were two immediate management strategies (poorly managed) of the Haiti earthquake?
- 120 rescued from rubble in two weeks with help from US troops.
- World Food Programme appealed for 14 million ration packs.
136
What were four longer-term management strategies of the Haiti earthquake 2004?
- Tents set up only provided for 25% of the homeless.
- 18 pop-up hospitals/clinics established.
- World Bank suspended Haiti's debt for 5 years.
- $11 billion given in foreign aid for reconstruction.
137
What was the cause of the Sichuan earthquake China 2008?
Convergent plate boundary of Indian and Eurasian plate, with subduction of Indian due to convection currents.
138
What were the epicenter, focus depth, and magnitude of the Sichuan China earthquake 2008?
- Magnitude: 8 on the moment magnitude scale.
- Focus depth: 19km (shallow focus).
- Epicenter: Sichuan province, southwest of Beichuan county.
139
What are three hazards of the Sichuan China earthquake 2008?
- Ground shaking.
- 5.36 million buildings collapsed.
- Landslides blocked railways.
140
What are four long-term impacts of the Sichuan earthquake 2008?
- 800km water pipeline damage.
- Chengdu airport temporarily closed.
- 2,380 dams weakened.
- 32 million farm animals died, affecting irrigation.
141
What were three immediate impacts of the Sichuan earthquake China 2008?
- 86,752 deaths.
- 3.36 million buildings collapsed.
- 1,100 killed in school buildings.
- 45,000 landslides
142
What were three immediate management strategies for the Sichuan earthquake?
- Chinese government sent in 140,000 troops for search and rescue.
- This included 100,000 parachutist volunteers.
- 250,000 residents evacuated from landslides.
143
What were five long-term management strategies of the Sichuan earthquake China 2008?
- World Health Organization helped address lack of clean water and disease prevention.
- Complaints about school building safety led to improved infrastructure.
- 248 roads repaired.
- One-child policy weakened.
- Beichuan planned a new city relocation due to damage.
144
What is the GDP of China?
$12,600 - emerging country.
145
What are two mitigation strategies for earthquakes?
- Land use zoning/hazard mapping.
- Hazard-resistant design and engineering defenses.
146
What is an example of land use zoning/hazard mapping for earthquake mitigation?
Japan created a National Seismic Hazard Map before the 2011 earthquake, with building restrictions in high-risk areas.
147
What is an example of hazard-resistant design and engineering defenses for earthquakes?
Tokyo Sky Tree in Japan uses NASA-inspired fluid dampers to reduce earthquake shaking vibrations by 50%.
148
What are five examples of earthquake adaptation methods?
- High-tech monitoring and forecasting to predict hazards.
- High technology monitoring for tsunami warnings.
- Modeling hazard impacts.
- Public education.
- Community preparedness.
149
What is an example of high technology forecasting to predict hazards for earthquakes?
Scientists are trying to predict earthquakes along the San Andreas Fault line in Parkfield, California.
150
What is an example of high-tech monitoring for earthquakes?
The DART tsunami warning system measures water displacement and floor movement, sending data to monitoring stations such as NOAA who help send warnings out
151
What is an example of modeling hazard impacts for earthquake adaptation?
Japanese scientists simulated the 2011 tsunami with a supercomputer to assess effects and strategies for future hazards.
152
What is an example of public education for earthquake adaptation?
Japan has an annual Disaster Prevention Day every 1st of September.
153
What is an example of community preparedness for earthquake adaptation?
During the 2004 Boxing Day tsunami, the elders of Thailand's Moken Tribe noticed the ocean's drawback and ordered villagers to run up the hills, resulting in only 1 out of 200 villagers dying.
154
What are two things to remember for math skills?
- If calculated workings are greater than the significance level, then the alternative hypothesis is true.
- Significance level of 0.05.
155
What are tsunamis unrelated to?
Tsunamis are unrelated to tidal movements through the moon, wind, and water.
156
How does a tsunami occur? (Step 1)
There is a megathrust earthquake under the ocean on a convergent plate boundary.
157
How does a tsunami occur? (Step 2)
This displaces a large amount of water.
158
How does a tsunami occur? (Step 3)
This displaced water, due to gravity, is pushed apart, which then causes a tsunami wave.
159
How does a tsunami occur? (Step 4)
The eventual friction of the seabed forces the wave to slow down and occupy less space, meaning the wavelength decreases and wave height increases.
160
How does a tsunami occur? (Step 5)
Then retreats after dragging debris back.
161
What are the characteristics of initial waves of tsunamis?
Small wave height less than 1m and long wavelength more than 100km.
162
What is a megathrust earthquake?
It occurs where on a convergent plate there is a bit of crust jolting very fast.
163
What magnitude do earthquakes have to occur for a tsunami to happen?
Above 9 on the moment magnitude scale.
164
What is the first step of how an earthquake occurs?
Build up of tectonic strain stores elastic energy in the crustal rocks. this occurs when rocks subduct on a destructive boundary of slip past each other on a conservative boundary
165
What is the second step of how earthquakes occur?
When pressure exceeds the strength of the fault, the rock fractures and this point of rupture is called the focus where the energy is released from
166
What is the third step of how earthquakes form?
The focus produces a sudden release of energy, creating seismic waves that radiate away from the hypocentre.
167
What is the fourth step of how earthquakes are formed?
The brittle crust rebounds either side of the fracture called elastic rebound, which is the ground shaking. the point directly above the hypocentre is the epicentre where most of the shaking occurs
168
What is a hazard?
An event that poses a threat to people, the economy, or the environment.
169
What scale is not used anymore?
The Richter scale.
170
What is the moment magnitude scale?
Measures the energy released during an earthquake related to the slip and movement on the fault area.
## Footnote
Each magnitude up has 10x more ground shaking.
171
What is the Mercalli scale?
A scale that rates earthquakes according to their intensity and how much damage they cause at a particular place on a scale of 1-7.
172
Why is the moment magnitude scale used instead of the Mercalli scale?
It depends on the quality of buildings and GDP and development of the area, so it is therefore biased.
173
What are the four theories for plate movement?
Mantle convection, subduction, slab pull, sea floor spreading.
174
What is mantle convection in explaining plate movement?
Earth's core produces heat by the radioactive decay of elements which heats up the lower mantle, creating liquid magma currents.
175
What is subduction as a cause of plate movement?
Two oceanic plates meet or the continental land oceanic plate meets, with the denser or older one sliding under another.
176
What is slab pull?
This process can follow subduction and is believed to be the leading cause now.
177
What is sea floor spreading as a cause of plate movement?
In the middle of oceans, mid-ocean ridges are formed when magma is forced up from the asthenosphere and hardens.
178
What provides evidence for sea floor spreading?
Paleomagnetism.
179
How does paleomagnetism work?
The Earth's magnetic poles reverse every 300,000 years and as magma rises, it cools and records the polarity of the Earth's magnetic field. can now see evidence of this througgh symetrical patterns of positive and negative stripes of rock on either side of mid ocean ridges
## Footnote
The symmetrical patterns of positive and negative magnetic stripes of rock on either side of mid-ocean ridges provide evidence that the sea floor is spreading.
180
Where do most destructive plate boundaries occur?
The Pacific Ring of Fire.
181
Where is the main conservative plate boundary?
San Andreas Fault.
182
Where is the main divergent plate boundary?
The American and Eurasian plates meeting in Iceland known as the Mid-Atlantic Ridge.
183
How big is the oceanic crust?
6-7km thick.
184
How big is the continental crust?
30-70km thick.
185
What is the inner core made of?
Iron and nickel.
186
What is the mantle made of?
Silicone, iron, and oxygen.
187
What is the top layer of the asthenosphere?
Lithosphere.
188
What is the top layer of the mesosphere?
Asthenosphere.
189
What is vulnerability?
Ability to cope, anticipate, resist, and recover from a natural hazard.
190
What is risk?
The potential that a community will face loss due to a hazard.
191
What is resilience?
The capacity for a community to overcome or recover from a hazard.
192
When was the PAR model developed?
1994.
193
What does the PAR model do?
Looks at the context of the physical disaster with its social economic pressures affecting the impacts and response.
194
What is the Parks model?
Shows how a country may respond to a hazard as a result of their socio-economic conditions.
195
What is a mega disaster?
From the UN, this would be 2000 plus deaths or 200,000 plus made homeless or GDP of a country reduced by at least 5%.
196
What are the three mega disasters in the case studies and why?
1. 2004 Boxing Day tsunami because 225,000 deaths spread across 11 countries.
2. 2011 Japanese tsunami because there were 25,000 deaths.
3. 2010 Iceland eruption E15 had a 1.6 billion dollar loss to the airline industry.
197
What makes it harder to cope with and recover from hazards?
Being in a multiple hazard zone.
198
What to call the Iceland Eyjafjallajökull eruption in the exam?
Eruption of E15 in 2010.
199
Example of a multiple hazard zone and what are its 6 hazards?
Philippines.
1. Flooding: have affected 11.5 million people.
2. Tropical storms: Typhoon Haiyan in 2013.
3. Drought: suffer from El Niño years.
4. Volcanoes: 25 active volcanoes.
5. Earthquakes: as on the convergent plate boundary of Eurasian, Pacific, and smaller Sundra plate.
6. Landslides: due to the northern mountains.
200
What is the hazard risk equation?
Risk = Hazard x Vulnerability.
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Five examples of key players in managing tectonic hazards from case studies?
1. National governments: Iceland evacuating 8,000 people.
2. IGOs: The World Bank pausing Haiti's debt for 5 years.
3. Local people: Heimaey Island in Iceland mitigating by diverting lava flows.
4. Scientists: British and American scientists in Montserrat monitoring and making an exclusion zone.
5. NGOs: USGS creating a hazard program with a checklist for response.
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What is more physical actions, mitigation or adaptation?
Mitigation.
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What is important to remember?
The DRC eruption had good funding to be forecasted and monitored; however, the government did not listen to this.
