Geology and Natural Hazards Week 1-2

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Questions and Answers

What occurs at convergent boundaries when two oceanic plates collide?

Both plates melt and form new oceanic crust.

Both plates push upwards to create mountain ranges.

The denser oceanic plate is subducted. (correct)

The less dense plate rises above the denser plate.

What is the primary driving force behind the movement of tectonic plates?

The rotation of the Earth.

Wind patterns influencing the ocean currents.

Convection currents in the earth's mantle. (correct)

Gravitational pull of the moons.

What characterizes transform boundaries?

New crust is generated as plates diverge.

Plates slide past each other with no crust creation or destruction. (correct)

Volcanic activity occurs regularly.

Crust is destroyed as plates collide.

What type of geological formation is expected at continental-continental convergent boundaries?

Mountain ranges due to upward pushed plates. Signup and view all the answers

What happens to the crust during seafloor spreading at divergent boundaries?

New oceanic crust is formed. Signup and view all the answers

The Benioff zone is related to which tectonic activity?

Earthquakes following the subducting slab. Signup and view all the answers

How does the age of oceanic crust relate to ocean depth?

Deeper oceans typically have older crust. Signup and view all the answers

What is a significant consequence of volcanic ash on commercial aircraft?

Potential engine failure Signup and view all the answers

Which is the result of the process of subduction?

Destruction of the subducted plate. Signup and view all the answers

Which of the following effects can volcanic eruptions have on global temperatures?

Blockage of sunlight Signup and view all the answers

What does volcanic tremor indicate in terms of monitoring volcanoes?

Seismic signals indicating magma movement Signup and view all the answers

What is the significance of InSAR in volcanic monitoring?

It maps surface displacement from space Signup and view all the answers

What characterizes a supervolcano?

Capability to produce an eruption exceeding 1000 km3 Signup and view all the answers

Which method is NOT used for monitoring heat and hydrothermal activity?

Magnetic field analysis Signup and view all the answers

Which volcanic gas monitoring technique involves collecting samples from fumaroles?

Direct sampling Signup and view all the answers

Which of the following is an implication of global climate change due to volcanic activity?

Hotter summers Signup and view all the answers

Which of the following describes the sequence of wave arrival during an earthquake?

P waves arrive first, followed by S waves Signup and view all the answers

What is a necessary condition for tsunami waves to be generated by undersea volcanic eruptions?

Large volumes of water must be displaced Signup and view all the answers

What role does the depth of water above a rupture play in tsunami generation?

Deep waters are essential for effective wave propagation Signup and view all the answers

Which of the following is NOT a method of tsunami hazard mitigation?

Creating underground shelters far from coastlines Signup and view all the answers

What primarily influences the generation of tsunami waves during an asteroid impact?

Height from which the asteroid falls Signup and view all the answers

During an earthquake, what does a short time between P waves and S waves indicate?

The earthquake is likely nearby Signup and view all the answers

Which type of wave is responsible for the most significant property damage during an earthquake?

Rayleigh waves Signup and view all the answers

Which geological feature is crucial for the formation of tsunami waves when a fault ruptures?

Seafloor deformation Signup and view all the answers

Which type of earthquake hazard does NOT contribute to tsunami generation?

Surface wave propagation Signup and view all the answers

What function do tsunami warning systems serve?

To detect early stages of tsunamis and notify affected areas Signup and view all the answers

What is one of the main advantages of delta regions for human settlement?

Abundant freshwater supply Signup and view all the answers

Which of the following is NOT a method of mitigating landslide risks?

Raising sea levels Signup and view all the answers

What primarily causes global sea level changes?

Tectonics and subsidence Signup and view all the answers

What role does 16O and 18O play in ocean and glacier dynamics?

Evaporation favors 16O and precipitation favors 18O, affecting sea water composition. Signup and view all the answers

What happens to the river profile as deltas grow seaward?

River profile lengthens Signup and view all the answers

How do foraminifera provide a proxy for past climate conditions?

Their shells integrate the oxygen isotope composition of seawater. Signup and view all the answers

What significant climatic observation has been made about the past 10,000 years?

It is the longest stable time in the past 400,000 years. Signup and view all the answers

Which delta is recognized as the greatest in the world?

Ganges-Brahmaputra Delta Signup and view all the answers

How does the city elevation change relative to the river as deltas grow?

The city gets lower relative to the river Signup and view all the answers

In terms of temperature and glacier length, what does a lower temperature indicate?

Longer glaciers are present due to less melt. Signup and view all the answers

What is the relationship between oxygen isotope ratios and snowfall temperatures as recorded in the Antarctic ice sheet?

Variations in isotopes record changes in snowfall temperature. Signup and view all the answers

Which feature of delta regions contributes to high agricultural productivity?

Rich sediment deposits Signup and view all the answers

Which factor primarily affects sea level rise in Southeast Asia?

Uplifted coasts Signup and view all the answers

What historic climatic event is characterized by significantly lower global temperatures?

The Little Ice Age. Signup and view all the answers

What has been the increase in global average temperatures over the past 200 years, according to proxy data?

0.6°C. Signup and view all the answers

What primary factor influences the composition of foraminifera shells during an ice age?

Concentration of 18O due to lower evaporation. Signup and view all the answers

What is the primary factor that determines frictional resistance in geological contexts?

Slope angle, load, and cohesion Signup and view all the answers

Which type of landslide is characterized by high speed and short runout?

Rockfall Signup and view all the answers

How does increased pore fluid pressure affect landslide potential?

It facilitates landslides by reducing friction Signup and view all the answers

What typical speed range is associated with debris flows?

1cm/s - 10m/s Signup and view all the answers

What is a common source of weakness in rock that can lead to landslides?

Fractures in any kind of rock Signup and view all the answers

What significant impact did the Vajont Dam landslide have during the initial filling?

It displaced 50 million m3 of water, creating a massive wave Signup and view all the answers

Which of the following landslide types can potentially transform into a debris avalanche?

Translational landslide Signup and view all the answers

What role does cohesion play in soil mechanics?

It contributes to the ability of soil grains to stick together Signup and view all the answers

Study Notes

Week 1 - Lectures 1 & 2 - 12 Aug 2024

Topography of Earth is more dynamic and active than Mars, with its crust being more plastic and deforming more readily.
Natural hazards are increasing due to the exponential growth of the global human population.
Human population growth, increased life expectancy, and efficient food production are linked to improved science and technology.
Everyday geological processes and interactions between spheres (hydrosphere, biosphere, etc.) contribute to natural disasters.
Human impact plays a role in the size and location of events. More people and buildings lead to more damage and casualties.
Catastrophe predictions are possible but challenging, with unpredictable cycles and many variables.
Recurrence interval increases linearly on a log scale and exponentially on a linear scale.
Magnitude is inversely proportional to frequency.

Week 2 - Lecture 3 - 19 Aug 2024

Earth's structure has unique chemical compositions and physical states impacting surface life.
Plate tectonics theory explains how major landforms are created from lithosphere movements.
Continental drift (1912) describes continents moving over geologic time.
Magnetic anomalies are evident in the Earth's magnetic field and its periodic reversals.

Week 2 - Lecture 3 - 19 Aug 2024 (cont.)

Divergent boundaries occur where plates move apart.
Convergent boundaries occur where plates collide, leading to subduction and mountain building.
Transform boundaries involve plates sliding past each other, causing earthquakes.

Week 3 - Lecture 4 - 26 Aug 2024

Stress and strain cause earthquakes.
Elastic deformation (reversible) and plastic deformation (not reversible) describe rock behaviour.
Elastic rebound theory explains energy release during earthquakes.
Seismic waves (body waves: P and S waves; surface waves: Rayleigh and Love waves) propagate during earthquakes.

Week 3 - Lecture 4 - 26 Aug 2024 (cont'd)

Different fault types (normal, reverse/thrust, strike-slip) relate to various geological environments (convergent, divergent and transform environments).
Magnitude of earthquakes is measured using seismic moment (related to length, width and slip of rupture x shear modulus).

Week 4 - Lecture 5 - 2 Sep 2024

Ground failure (fault rupture, landslides, liquefaction) are earthquake hazards.
Ground shaking is an adverse effect of earthquakes, with devastating impacts depending on the distance from the source.
Surface faulting results in visible offsets and is a hazard to structures.
Earthquakes can trigger landslides, affecting populated regions.

Week 4 - Lecture 5 - 2 Sep 2024 (cont'd)

Flooding due to landslides impacting water bodies can generate a disastrous situation.
Liquefaction, a ground failure, involves saturated, loosely packed soils becoming fluid during earthquakes.
The effect of earthquakes on changes in land level and shoreline is considerable.

Week 5 - Lecture 6 - 9 Sep 2024

Tsunamis are generated by vertical deformation/movement from earthquakes.
Tsumanis have very large wavelengths and wave heights, which lead to significant damages and harm in coastal areas.
Tsunami wave speed is controlled by water depth, causing faster waves in deep water and slower waves in shallow water.

Week 5 - Lecture 6 - 9 Sep 2024 (cont'd)

Factors influencing tsunami wave height include earthquake magnitude (greater magnitude - larger tsunami); area of rupture and rate of water displacement.
Underwater ruptures of normal faults, thrust faults and megathrust faults are significant sources for tsunamis.

Week 6- Lecture 7 - 16 Sep 2024

Different types of volcanoes (shield volcanoes, stratovolcanoes, cinder cones and Calderas) have different eruptive styles.
Explosive volcanic eruptions can lead to dangerous pyroclastic flows, ash falls, and lahars, which have widespread effects.
Volcanic eruptions can cause changes to topography and bathymetry.

Week 6 - Lecture 7 - 16 Sep 2024 (cont'd)

Volcanic eruptions can cause changes to topography and bathymetry.
Types of magma (basaltic, andesitic, rhyolitic) have different compositions, viscosity, and temperatures which affect eruptive styles.

Week 7 - Lecture 8 - 23 Sep 2024

Volcanic hazards occur without eruptions (e.g. ground shaking, fractures and fissures)
Gases released during volcanoes and volcanic activities could cause harm to humans and animals through CO2 suffocation

Week 7 - Lecture 8 - 23 Sep 2024 (cont'd)

Volcanic hazards include volcanic mudslides (lahars) and landslides, which can result in considerable losses and harms.
Monitoring volcanic activity helps to predict eruptions and mitigate related risks.

Week 8- Lecture 9 - 7 Oct 2024

Landslides are the downslope movement of rock, debris and/or mud, depending on the slope angle, moisture content, water saturation and external factors like earthquakes/explosions.
Rotational and translational slides are different types of landslide movements.

Week 8 - Lecture 9 - 7 Oct 2024 (cont'd)

The processes involve the interplay of driving forces (gravity) and resisting forces (cohesion, friction and strength of materials).
Landslides can result in different damages depending on the driving force, the angle of repose, and external factors.
Types of monitoring/mitigation strategies for landslides are also included

Week 9 - Lecture 10 - 14 Oct 2024

Delta regions are typically located where rivers enter oceans, seas or lakes.
The factors causing people to choose to live in delta regions include the flat terrain (for easy transport, farming), and fresh water
Deltas develop over time, as rivers carry sediment.
The rising of sea level will threaten delta regions and lead to various impacts on people and their livelihoods.

Week 9 - Lecture 10 - 14 Oct 2024 (cont.)

Rising sea levels are a global concern, caused by various factors (e.g., glacial melt, thermal expansion of seawater).
Sea levels are rising leading to floods and the salinization of fresh water resources from the aquifers near the coasts in the delta regions.

Week 10- Lecture 11 - 21 Oct 2024

Cyclones are rotating storms that derive energy from warm ocean water.
Warm water, strong winds, and latent heat of vaporisation from oceans are essential for cyclone formation.
Cyclones develop in tropical and subtropical areas of oceans near the equator.

Week 10 - Lecture 11 - 21 Oct 2024 (cont.)

Cyclones are associated with strong winds (that can damage infrastructure, knock down buildings etc), heavy rainfall (that can lead to flooding), storm surges (which push ocean water onto coastal areas).
The Coriolis effect influences the rotational direction of cyclones in different hemispheres
Cyclones (e.g. hurricanes, typhoons) can cause wide-ranging damages, including death, injuries, building destruction, infrastructure damage (for example, knocking down buildings) and substantial economic losses.

Week 11/12 - Lecture 12 - 28 Oct 2024 / 4 Nov 2024

Climate change is the long-term shift of weather that affects various aspects of the Earth's system, including atmosphere, hydrosphere, geosphere, biosphere, and cryosphere.
Variations in Earth's orbit affect solar radiation receipt, which in turn leads to temperature variations.
Greenhouse gases trap heat radiated from the Earth, warming the planet. Human activities are major contributors, especially burning fossil fuels.

Week 11-12 - Lecture 12 - 28 Oct 2024 / 4 Nov 2024 (cont.)

Natural factors (e.g., volcanic eruptions and Milankovitch cycles) can also influence climate.
Increased greenhouse gases and their warming effects have global consequences, including rising sea levels, more extreme weather events, and threats to human societies.
Monitoring and measuring climate conditions include methods like analyses of ice cores, tree rings and sediments, which can provide insights into past climate conditions.

Week 11/12 - Lecture 12 - 28 Oct 2024 / 4 Nov 2024 (cont.)

The idea of geoengineering addresses ways to manage the direct consequences of climate change.
Geoengineering approaches attempt to physically manipulate the Earth's environment to reduce global warming, such as increasing reflectivity of clouds, promoting plant growth, or capturing CO2 from the atmosphere.

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Description

This quiz covers the key concepts from the first two weeks of geology lectures, focusing on Earth's dynamic topography, the impact of human population growth on natural hazards, and the processes contributing to these events. Additionally, it explores the role of scientific and technological advancements in understanding geological phenomena and predicting catastrophes.