Tectonics Flashcards
(91 cards)
1
Q
Earthquake Distribution
A
- About 95% occur near plate boundaries.
- Many occur around the ‘Ring of Fire’ surrounding the Pacific Ocean.
- Most powerful earthquakes often associated with convergent or conservative plate boundaries.
- Intra-plate earthquakes occur away from plate boundaries, linked to hot spots or old fault lines.
2
Q
- Volcano Distribution
A
- Most active volcanoes located at or near plate boundaries.
- Around 75% found around the ‘Ring of Fire’.
- Volcanoes occur at convergent and divergent plate boundaries.
- Also found at hot spots within plates, e.g., Hawaii.
3
Q
Tsunami Distribution
A
- Over 70% of tsunamis occur around the Pacific Ocean.
- Other percentages: Mediterranean Sea (15%), Caribbean Sea and Atlantic Ocean (9%), Indian Ocean (6%).
- Primarily caused by tectonic activity, often at convergent boundaries.
4
Q
Plate Boundaries
A
- Locations where tectonic plates meet.
- Types: Divergent (plates moving apart), Convergent (plates moving together), Transform (plates moving past each other).
- Convergent boundaries categorized as Oceanic-Continental, Oceanic-Oceanic, Continental-Continental.
5
Q
Intra-plate Earthquakes & Volcanoes
A
- Some occur away from plate boundaries.
- Intra-plate earthquakes can happen anywhere, caused by tectonic stresses or zones of weakness.
- Examples: New Madrid earthquake in 1812, 2011 Virginia earthquake.
- Hotspot volcanoes form over stationary magma plumes in the asthenosphere.
- Example: Hawaii, forming a chain of volcanic islands with the oldest furthest from the plume.
6
Q
Earth’s Internal Structure
A
Earth consists of three main layers: crust, mantle, and core.
Crust divided into continental (thicker, less dense) and oceanic (thinner, denser) types.
Mohorovičić discontinuity (Moho) marks the boundary between crust and mantle.
Mantle: upper (rigid lithosphere and semi-molten asthenosphere) and lower layers.
Core: inner (solid iron) and outer (semi-molten iron and nickel) parts.
7
Q
Aesthnosphere
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The upper layer of the earth’s mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur
8
Q
Plate Tectonic Theory Development
A
Plates move over the asthenosphere.
Debate over mechanisms causing movement.
Mantle convection: heat from core creates convection currents, driving plate movement
9
Q
Plate Tectonic Processes
A
Seafloor spreading: evidence from paleomagnetism and lava cooling at mid-ocean ridges.
Subduction and slab pull: denser plate subducts under lighter one, pulling it down with gravity.
10
Q
Convergent plate boundary
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Plates move towards each other, causing earthquakes, volcanic eruptions, and fold mountains.
11
Q
Divergent boundary
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Plates move apart, creating new crust, earthquakes, and volcanic eruptions.
12
Q
Collision boundary
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Two continental plates collide, forming fold mountains without volcanic activity.
13
Q
Transform boundary
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Plates slide past each other, causing earthquakes but no volcanic activity.
14
Q
Physical Processes Impact
A
Magnitude and type of volcanic eruptions and earthquakes vary at different plate boundaries.
Basaltic magma at divergent boundaries leads to mild, shallow earthquakes and effusive eruptions.
Rhyolitic magma at convergent boundaries causes explosive eruptions and strong earthquakes due to pressure buildup in the Benioff zone.
Transform boundaries result in powerful earthquakes due to plate sticking, but no volcanic activity.
15
Q
What are the three types of seismic waves generated by an earthquake?
A
Primary (P) waves: Fastest, travel through liquids and solids, cause back-and-forth shaking, least damaging.
Secondary (S) waves: Slower than P waves, only travel through solids, cause sideways motion, more damaging.
Love (L) waves: Slowest, surface waves, cause side-to-side motion, most damaging.
16
Q
What are the primary hazards associated with earthquakes?
A
Ground shaking
Crustal fracturing
Landslides and avalanches
Liquefaction
Flooding from tsunamis
17
Q
Crustal fracturing
A
When the movement causes the Earth’s crust to crack
18
Q
Liquefaction
A
When the shaking causes particles in the ground to move further apart causing them to act like a liquid rather than a solid
19
Q
What are secondary hazards resulting from primary earthquake hazards?
A
Secondary hazards include those triggered by the primary effects such as landslides due to ground shaking or flooding from a tsunami impacting further inland.
20
Q
What are the primary hazards of volcanic eruptions?
A
Pyroclastic flow
Lava flow
Ash falls
Gas eruptions
Lahars
Jökulhlaups
21
Q
Pyroclastic flow
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A mix of dense, hot, rock, ash and gases
21
Q
Lava flow
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Most move slowly enough that they are not a risk to human life but can reach over 1000oC
21
Q
Ash falls
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Can travel many km, causing injuries, damage, deaths and disruption to transport
21
Q
Gas eruptions
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Gases trapped in the magma are released during an eruption, they may form gas clouds which are hazardous to health
21
Lahars
A mixture of rocks, mud and water which flow down the volcano. They are fast-flowing and destroy everything in their path
21
Jökulhlaups
Floods caused by a sudden release of water and rocks when glacial ice is melted by the eruption
21
What are secondary hazards resulting from volcanic eruptions?
Secondary hazards are consequential effects like lahars and jökulhlaups, often resulting from the combination of volcanic activity and environmental conditions such as melting ice or heavy rainfall.
21
What are the main causes of tsunamis?
Sub-marine earthquakes at subduction zones causing displacement of the sea bed and water column.
Landslides, underwater volcanic eruptions, and rarely, meteor strikes.
21
How does a tsunami form as a result of an earthquake?
An undersea earthquake displaces the sea bed, forcing water upwards. As the wave travels toward land, it slows down, its wavelength compresses, and its height increases, potentially causing massive flooding upon reaching the shore.
21
What happens as a tsunami wave approaches the shore?
The wave height increases as the wave slows down and compresses. Just before the tsunami hits, the water may recede significantly, exposing the sea bed, followed by the massive wave hitting the shore
22
Why are tsunamis most common in the Pacific Ocean's "Ring of Fire"?
The "Ring of Fire" is home to many subduction zones, where oceanic plates dive beneath continental plates, leading to frequent and powerful sub-marine earthquakes that can generate tsunamis.
23
What differentiates a natural hazard from a disaster?
A natural hazard is a potential threat to humans, their property, and the environment, caused by natural processes. A disaster occurs when a natural hazard actually results in significant harm to people, the environment, or the economy, exceeding the affected community's ability to cope using its own resources.
24
What factors influence an area's vulnerability to natural hazards?
Level of development
Population density
Size of the hazard
Preparation and planning
An area's vulnerability increases with its susceptibility to damage and decreases with its ability to cope and respond.
25
What is the hazard risk equation?
Risk = (Hazard x Vulnerability) / Capacity to cope. This equation assesses an area's risk by considering the magnitude of the natural hazard, the area's vulnerability, and its capacity to cope with the disaster.
26
What are some key factors affecting a country or area's resilience to disasters?
Economic stability
Infrastructure quality
Effective governance and emergency planning
Community preparedness
Access to resources and information
27
What does the Pressure and Release Model (PAR) illustrate?
The PAR model demonstrates how socio-economic factors increase vulnerability and reduce resilience to hazards. It consists of root causes, dynamic pressures, and unsafe conditions, culminating in the disaster risk.
28
How do volcanic eruptions impact developed vs. developing/emerging countries differently?
Developed countries might experience less human loss but significant economic costs, while developing/emerging countries face higher casualties, infrastructural damage, and long-term economic disruptions, as seen in the comparisons between Eyjafjallajökull (Iceland) and Merapi (Indonesia).
29
Compare the impact of earthquakes in developed and developing/emerging countries.
Developed countries may see significant property and economic loss with lower casualties, while developing countries suffer extensive casualties, infrastructural destruction, and profound economic impacts, as shown by the Amatrice (Italy) and Gorkha (Nepal) earthquakes.
30
How do tsunamis affect developed vs. developing/emerging countries?
In developed countries, tsunamis can cause massive economic losses and infrastructural damage, whereas in developing/emerging countries, the human toll and destruction of homes and livelihoods can be more severe, as illustrated by the 2011 Japan and 2004 Indian Ocean tsunamis.
31
Why is comparing the impact of natural hazards on different countries complex?
Impacts vary not just by development status but also due to factors like population density, hazard magnitude, and preparedness levels. Economic costs are generally higher in developed countries, but the human cost and societal disruption can be more acute in less developed areas.
32
Difference between magnitude and intensity in earthquakes.
Magnitude measures the energy released at the earthquake's focus, using scales like the Moment Magnitude Scale (MMS). Intensity measures the earthquake's effects on people, buildings, and the natural environment, using the Modified Mercalli Intensity Scale.
33
What is the Moment Magnitude Scale (MMS)?
The MMS is a logarithmic scale used to measure the energy released by an earthquake, ranging from 1 (not felt) to 10 (massive). Each whole number increase represents a tenfold increase in amplitude and 32 times more energy release.
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What does the Modified Mercalli Intensity Scale measure?
It measures the intensity of an earthquake based on its observed effects on people, buildings, and the natural environment, ranging from I (not felt) to XII (total destruction).
35
How is the size of a volcanic eruption measured?
The VEI measures eruption size based on the volume of material ejected, eruption cloud height, and eruption duration, on a logarithmic scale from 0 to 8.
36
What information is included in tectonic hazard profiles?
Hazard profiles compare tectonic events based on magnitude, speed of onset, areal extent, duration, frequency, and spatial predictability.
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What are the advantages of using hazard profiles?
They allow comparison of different hazards, same hazards under different conditions, and are useful for planning. They highlight the physical characteristics important for understanding and mitigating hazards.
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What are the disadvantages of using hazard profiles?
They may overlook the influence of human factors, are not suitable for multi-hazard events, and can be subjective in their creation and interpretation.
39
Compare the impact of similar magnitude earthquakes in Haiti (developing) and Italy (developed).
Despite similar magnitudes, Haiti's 2010 earthquake resulted in 220,000 deaths, significant homelessness, and economic damages of US$7.8 billion, largely due to weaker infrastructure and poor emergency response. Italy's 2016 earthquake saw 299 deaths, 4,500 homeless, and US$4 billion in damages, with better response mechanisms and stronger infrastructure mitigating some impacts.
40
What is the relationship between inequality and vulnerability?
Higher levels of inequality increase vulnerability due to limited access to education, housing, healthcare, and income. This impacts resilience when facing natural hazards.
41
How does the Human Development Index (HDI) relate to vulnerability in tectonic hazards?
Low HDI reflects in lower education, poor quality housing, lack of healthcare, and poor water and diet quality, increasing vulnerability to tectonic hazards.
42
How does governance affect vulnerability and resilience to tectonic hazards?
Good governance improves resilience and coping capacity during hazard events through effective planning, education, prediction, and preparation. Poor governance increases vulnerability due to lack of preparedness and corruption.
43
What geographical factors impact vulnerability to tectonic hazards?
Population density, accessibility/isolation, and urbanization impact vulnerability by affecting evacuation, aid delivery, communication, and the concentration of people and buildings.
44
How did the context of Haiti influence the impact of the 2010 earthquake?
Government corruption, poor housing quality, high poverty levels, and poor infrastructure led to severe impacts: 220,000 dead, 300,000 injured, 1.5 million homeless, and US$7.8 billion damages.
45
How did the context of Sulawesi, Indonesia, influence the impact of the 2018 earthquake?
Lack of education on hazards, rural poor housing, lack of tsunami warning systems, and poor infrastructure resulted in 4,340 deaths, 10,670 injured, and 206,500 displaced.
46
How did the context of Amatrice, Italy, influence the impact of the 2016 earthquake?
Non-compliance to anti-seismic laws, insurance, and earthquake drills helped mitigate impacts: 299 deaths, 388 injured, 4,500 homeless, and over US$4 billion in damages.
47
What are the general trends in tectonic hazards since 1960?
The number of recorded disasters has increased, mainly due to floods and extreme weather. The number of tectonic disasters has remained steady. Reasons include increased population and urbanization, and improved monitoring and reporting.
48
What factors have contributed to the increased reporting of disasters since 1960?
- World population growth (from 3 billion to over 8 billion)
- Increased population density in urban and coastal areas
- Improved disaster monitoring and reporting systems
49
How has the number of deaths from tectonic hazards changed over time?
The number of deaths has decreased due to better building construction, increased monitoring, greater preparation and planning, and improved warning systems.
50
How have the economic costs of disasters changed since 1960?
The economic cost has increased, affected by development level, more sophisticated and expensive infrastructure, and the growing impact on GDP in developing countries.
51
What are the impacts of tectonic mega-disasters?
Tectonic mega-disasters can lead to massive economic losses, significant death tolls, widespread environmental damage, and have regional or global significance, affecting global interdependence and policies.
52
What challenges affect the accuracy and reliability of disaster data?
- Initial focus on search, rescue, and recovery
- Difficulty in data collection in remote areas
- Complex factors affecting trends, making interpretation challenging
53
What are some examples of tectonic mega-disasters and their impacts?
- 2004 Asian tsunami: 225,000 deaths, affected 18 countries, US$10 billion in damages.
- 2010 Eyjafjallajokull eruption: Disrupted global air travel, significant economic losses for countries dependent on exports like Kenya.
- 2011 Tohoku earthquake and tsunami: US$360 billion in losses, impacted Japan's energy policy and global trade.
54
What is a multiple-hazard zone and how can hydrometeorological hazards contribute to a tectonic disaster?
A multiple-hazard zone is an area susceptible to multiple types of hazards. Hydrometeorological hazards, like heavy rains, can trigger landslides or exacerbate the impacts of tectonic events, such as earthquakes.
55
Why is the Philippines considered a multiple-hazard zone?
The Philippines faces multiple hazards due to its location on major and minor plate boundaries and within the tropical cyclone zone, making it prone to typhoons, earthquakes, volcanic eruptions, tsunamis, and landslides.
56
Describe the geographic location of the Philippines.
An island nation in Southeast Asia, in the Western Pacific Ocean, consisting of over 7,600 islands with a population of 115.6 million (2022) and a high urban population percentage.
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What factors contribute to the high vulnerability of the Philippines to hazard events?
High urban population density, coastal living increasing vulnerability to storm surges and tsunamis, deforestation increasing landslide risks, and developing country status limiting resources for planning and preparation.
58
Why is the Philippines prone to tectonic activity?
It's located at the boundaries of major and minor plate boundaries and on the western edge of the Pacific Ring of Fire, leading to significant volcanic activity and earthquakes.
59
What are the key points about volcanoes and earthquakes in the Philippines?
The Philippines has 24 active volcanoes, with Mount Pinatubo's 1991 eruption being significant, and it experiences earthquakes due to its location near subduction zones.
60
Why is the Philippines at risk of tsunamis?
Its location in the Western Pacific makes it vulnerable to tsunamis, which may result from both volcanic eruptions and earthquakes.
61
Describe the typhoon risk in the Philippines.
Located in the tropical cyclone zone, the Philippines is hit by 15-20 typhoons a year, with Typhoon Yolanda in 2013 being particularly devastating.
62
What causes landslides in the Philippines?
The mountainous landscape, along with triggers from earthquakes, volcanic eruptions, and typhoons, and increased due to deforestation and high population density.
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How does the economic status of the Philippines affect its disaster preparedness and recovery?
As a developing country with a low GDP per capita, the Philippines lacks the financial resources for effective planning, preparation, and recovery from multiple hazard events.
64
What is the difference between prediction and forecasting in the context of tectonic hazards?
Prediction is about knowing when and where a hazard will occur, while forecasting provides a percentage chance of a hazard occurring over a set period.
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Can earthquakes be predicted? What are scientists focusing on to improve forecasting?
No, earthquakes cannot be precisely predicted. Research focuses on seismic gap theory, radon emissions, and animal behavior to improve risk forecasting.
66
What are the signs of an impending volcanic eruption?
Signs include magma rising (detected by heat sensors/satellites), surface level changes, increased gas emissions, and increased seismic activity.
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How does the tsunami warning system work following an earthquake?
After an earthquake is detected by seismometers, ocean monitoring technology detects tsunamis, enabling warnings to be issued to potentially affected coastal areas.
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What are the stages of the hazard management cycle?
The stages include response, recovery, mitigation, and preparedness, influenced by development level, magnitude of hazard, governance quality, and available aid.
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What are the advantages of using the hazard management cycle?
It helps organizations and individuals prepare for and respond to hazards, identifies potential hazards, reduces risks, saves lives, and improves preparedness.
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What does Park's model illustrate?
Park's model, or the disaster response curve, shows the impact of a hazard event on quality of life over time, highlighting different management strategies before, during, and after an event.
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How does Park's model vary between developed and developing countries?
Developing countries tend to be impacted more and recover more slowly, which is reflected in their disaster response curves compared to developed countries.
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What are the advantages of using Park's model?
It's applicable to a range of hazards, assesses risk and preparedness, and allows for comparison of responses based on development levels.
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What are the disadvantages of using Park's Model?
Only shows the impact of a single event, not multiple or cascading events.
Lacks quantitative data (e.g., number of deaths, extent of building destruction).
Does not include preventative measures within the model.
Resource-intensive, potentially excluding smaller or less developed communities due to implementation costs.
74
How can the impact of earthquakes be modified before the event?
Through the construction of earthquake-resistant buildings to reduce impacts on people, due to the challenge of modifying earthquakes themselves as they occur without warning.
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What strategies are used to modify volcanic hazards before an event?
Hazard risk mapping with GIS for high-risk area identification, land use zoning to prevent development in risky areas, draining crater lakes, and constructing barriers/channels to divert lava flows.
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What are the strategies for modifying the impact of tsunamis?
Land use zoning to limit coastal construction, building offshore barriers and sea walls, and replanting mangrove forests to absorb wave energy.
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How can the vulnerability of populations to tectonic hazards be reduced?
Through land use zoning, hazard-resistant buildings, improving services/infrastructure, evacuation planning, education on hazard response, improved storage of essentials, and monitoring/warning systems.
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What strategies can reduce loss after a tectonic hazard event?
Efficient aid and recovery including evacuation, search and rescue teams, emergency and short-term aid, development aid for reconstruction, and insurance for rebuilding.
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What is the role of planners and engineers in disaster modification?
Planners and engineers are involved in land-use zoning, designing hazard-resistant structures, and creating engineering defenses like sea walls and lava flow diversions.
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How do community preparedness and adaptation strategies modify vulnerability and resilience?
Through high-tech monitoring and prediction, education on hazard response, planning of evacuation routes, and ensuring community engagement in preparedness activities.
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What roles do NGOs and insurers play in modifying loss after a tectonic event?
NGOs provide emergency, short, and longer-term aid, while insurers offer financial support for rebuilding. Both are crucial for effective recovery and reducing economic loss.
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How do affected communities contribute to modifying loss after a hazard event?
Communities support each other with shelter, aid in search and rescue efforts, and help in distributing emergency supplies, playing a key role in immediate post-disaster response.
