Midterm Studying Flashcards
- What is the cause of the Earth’s geomagnetic field?
a.Convection of the mantle
b.Flow of the outer core
c.Solar storms
d.Radioactivity within the Earth
B. Flow of the outercore
Describe the bulk rheology and composition of the mantle asthenosphere?
a.Solid, ductile, plastic silicate rock
b.Solid, brittle, elastic silicate rock
c.Liquid silicate rock
d.Liquid iron/nickel allo
a. Solid, ductile, plastic silicate rock
The mantle asthenosphere is composed of silicate rocks that are solid but behave in a ductile, plastic manner due to high temperatures and pressures. This allows for slow, convective flow, which plays a critical role in plate tectonics and the movement of Earth’s lithospheric plates.
If current plate tectonic motions continue millions of years into the future, what is likely to happen to the continent of Africa?
a.South Africa will collide with Antarctica, forming a new continental collision zone.
b.The Indian Ocean will subduct beneath East Africa, forming a new volcanic arc.
c.East Africa will split from the main part of Africa, forming a new ocean in between.
d.North Africa will separate from Europe (Eurasia), and the Mediterranean Sea will grow into an ocea
c. East Africa will split from the main part of Africa, forming a new ocean in between.
The East African Rift is an active continental rift zone where the African Plate is slowly splitting into two parts: the Somali Plate and the Nubian Plate. If this tectonic activity continues over millions of years, East Africa will eventually break away from the rest of the continent, and a new ocean basin will form between them.
Why might Vancouver experience larger shaking intensity during a Cascadia megathrust earth-quake than Victoria, even though Vancouver is situated further from the plate boundary?
a.Because more people live in Vancouver than Victoria, so theriskis higher in Vancouver.
b.Because the earthquake hypocenter (the point on the fault where the rupture starts) is likely to lie directlybeneath Vancouver.
c.Because Vancouver lies closer to the Cascade arc volcanoes (e.g. Mt Baker) than Victoria, and the earth-quake will likely trigger volcanic activity.
d.Because much of Vancouver is built on soft sedimentary rocks which amplify ground shaking (site effects),whereas most of Victoria is built on harder bedroc
d. Because much of Vancouver is built on soft sedimentary rocks which amplify ground shaking (site effects), whereas most of Victoria is built on harder bedrock.
Vancouver is built on softer sedimentary soils, which can amplify seismic waves, increasing the shaking intensity during an earthquake. In contrast, Victoria, which is built more on hard bedrock, would experience less amplification of shaking. This difference in ground materials is a key factor in why Vancouver might experience stronger shaking than Victoria despite being farther from the plate boundary.
- When were the theories of Continental drift and Plate tectonics developed?
a.They were both developed in the 1910s.
b.Continental drift was developed in the 1910s, and Plate tectonics in the 1960s.
c.Plate tectonics was developed in the 1910s, and Continental drift in the 1960s.
d.Continental drift was developed during the Second World War, and Plate tectonics in the 1960s.e.Plate tectonics was developed during the Second World War, and Continental drift in the 1960
b. Continental drift was developed in the 1910s, and Plate tectonics in the 1960s.
The theory of Continental Drift was proposed by Alfred Wegener in the 1910s, suggesting that continents were once joined together in a supercontinent called Pangaea and have since drifted apart. The theory of Plate Tectonics emerged in the 1960s after further research, such as seafloor spreading and the mapping of global earthquake zones, provided the mechanism for how continents move.
Approximately how much more seismic moment (“energy”) is released in aMw6.0 earthquakethan aMw5.0 earthquake?
a.6/5 = 1.2 times as much
b.106/105= 10 times as much
c.(106/105)1.5 =∼32 times as much
d.(106/105)10 = 100 times as much2
The correct answer is:
c.(106/105)1.5 =∼32 times as much
The moment magnitude scale (Mw) is logarithmic, meaning that each whole number increase on the scale corresponds to a release of about 31.6 times more energy (or approximately 32 times). Therefore, a Mw 6.0 earthquake releases significantly more energy than a Mw 5.0 earthquake.
- What occurs during planetary differentiation?
a.Smaller planetesimals collide to form a larger planetary bodies.
b.A meteorite bombardment adds new material to the planet.
c.The planet melts and separates into an iron-rich core and silica-rich mantle.
d.Gas condenses to dust particles, which in turn aggregate to larger grains and roc
The correct answer is:
c. The planet melts and separates into an iron-rich core and silica-rich mantle.
During planetary differentiation, a planet or planetary body undergoes melting due to heat generated from various sources (such as radioactive decay and impacts). As it melts, denser materials, like iron, sink to form a core, while lighter materials, like silicates, rise to form the mantle and crust. This process leads to the formation of distinct layers within the planet.
- Which best describes the relationship betweenstressandstrain?
a.Strain causes stress.
b.Stress causes strain.
c.Stress and strain describe the same thing.
d.Stress and strain are mutually exclusive
The correct answer is:
b. Stress causes strain.
In the context of geology and materials science, stress refers to the force applied to a material, while strain is the deformation that results from that stress. When stress is applied to a material, it deforms, which is the strain. Thus, stress leads to strain, not the other way around.
- The main mechanism for heat transfer through the mantle mesosphere and asthenosphere is:
a.convection.
b.conduction.
c.radiation.
d.all of the above contribute to heat transfer, in roughly equal proportion
The correct answer is:
a. convection.
The main mechanism for heat transfer through the mantle mesosphere and asthenosphere is convection. In these regions, the material is solid but can flow slowly, allowing heat to be transferred through the movement of the mantle material. While conduction does occur, convection is the dominant process due to the high temperatures and pressures involved. Radiation is negligible in these contexts.
- If the BC government built an earthquake early warning system on Vancouver Island, what would happen to the seismichazard and seismicriskin Victoria?
a.The hazard would decrease, but the risk would stay the same.
b.The hazard would stay the same, but the risk would decrease.
c.Both the hazard and the risk would decrease.
d.Both the hazard and the risk would stay the same
The correct answer is:
b. The hazard would stay the same, but the risk would decrease.
The seismic hazard refers to the likelihood of an earthquake occurring in a given area, which would remain unchanged regardless of an early warning system. However, an earthquake early warning system would provide advance notice of seismic activity, allowing people to take protective actions, thus reducing the potential for injury, damage, and loss—thereby decreasing the overall seismic risk.
What is liquefaction?
a.When water is released into the mantle at subduction zones, leading to arc volcanism.
b.When mantle rocks undergo decompression melting at mid-ocean ridges, forming liquid magma.
c.When saturated sedimentary rocks liquefy during earthquake shaking.
d.When waste-water from fracking is buried at depth, increasing pore pressures and triggering induced earth-quakes.
The correct answer is:
c. When saturated sedimentary rocks liquefy during earthquake shaking.
Liquefaction occurs when saturated sediments lose their strength and behave like a liquid due to the shaking from an earthquake. This process can lead to significant ground deformation and damage to structures, as the solid ground can momentarily act like a liquid, causing buildings and other infrastructure to sink or tilt.
What is a postglacial earthquake?
a.Any earthquake that occurred during the Holocene (i.e., since the end of the last Ice Age)
b.An earthquake caused thawing of the ground surface following the melting of ice sheets and glaciers
c.An earthquake caused by shearing stresses from the flow of glaciers over the Earth surface
d.An earthquake caused by bending stresses following the melting of ice sheets and glacie
d. An earthquake caused by bending stresses following the melting of ice sheets and glaciers.
Postglacial earthquakes are typically associated with the rebound of the Earth’s crust after the weight of ice sheets and glaciers is removed due to melting. As the crust adjusts and rebounds, it can generate earthquakes due to the release of built-up stresses.
What is the earthquake epicenter?
a.The point on the fault plane where the earthquake rupture starts.
b.The point on the fault plane where the earthquake rupture stops.
c.The point on Earth’s surface immediately above where the earthquake rupture starts.
d.The center point of the ruptured fault plane.e.The point on Earth’s surface where the largest intensity was felt.3
c. The point on Earth’s surface immediately above where the earthquake rupture starts.
The epicenter is the location on the Earth’s surface that is directly above the focus (or hypocenter), where the earthquake rupture initiates. It is often used to describe the location of an earthquake in reports and maps.
What class of earthquake was the 2011Mw9.0 Tohoku (Japan) earthquake?
a.A shallow crustal earthquake
b.A subduction megathrust earthquake
c.An intermediate depth, intraslab earthquake
d.A deep earthquake
b. A subduction megathrust earthquake.
The 2011 Mw 9.0 Tohoku earthquake occurred at the boundary between the Pacific Plate and the North American Plate, where the Pacific Plate is being subducted beneath the North American Plate. This type of earthquake is characterized by a large magnitude and significant energy release, typical of megathrust earthquakes associated with subduction zones.
Why, in some arid countries, are human settlements often located along active faults?a.The water table can pond against a fault, forming springs and providing a source of water.
b.Faults form valleys, along which rivers flow, providing a source of water.
c.Earthquake shaking produces sedimentary rocks, providing better conditions for farming.
d.Faulting parallels coastlines, where people live in order to trade and fis
a. The water table can pond against a fault, forming springs and providing a source of water.
In arid regions, faults can create fractures that allow groundwater to rise to the surface, forming springs. This provides a crucial water source for human settlements, making these locations desirable even though they are situated along active faults.
What is a natural hazard?
a) A hazardous event that causes economic loss
b) A natural event that is potentially dangerous
c) A human-induced disaster
d) A method of disaster response
b) A natural event that is potentially dangerous
What distinguishes geological hazards from weather or climate hazards?
a) Geological hazards are always more deadly
b) Geological hazards are caused by processes occurring in the solid Earth
c) Weather hazards are more common than geological hazards
b) Geological hazards are caused by processes occurring in the solid Earth
Which of the following best describes a natural disaster?
a) A natural event that occurs randomly
b) A hazardous event that causes loss of life, damage, or economic losses
c) Any weather-related phenomenon
d) A geological event without any impact on humans
b) A hazardous event that causes loss of life, damage, or economic losses
What is the relationship between magnitude and frequency of hazardous events?
a) They are directly proportional
b) They are inversely proportional
c) There is no relationship
d) Frequency always increases with magnitude
b) They are inversely proportional
What does risk describe in the context of natural hazards?
a) The likelihood of a hazardous event occurring
b) The number of people affected by a disaster
c) The economic costs of disaster recovery
d) The total number of disasters in a year
a) The likelihood of a hazardous event occurring
Which of the following activities is part of emergency management?
a) Risk assessment
b) Disaster recovery
c) Preparedness
d) All of the above
d) All of the above
What global trend is affecting weather and climate hazards?
a) Decrease in population
b) Increased urbanization and global warming
c) Reduction in economic costs
d) Stabilization of geological hazards
b) Increased urbanization and global warming
What is the process by which planets, including Earth, formed from a spinning cloud of gas and dust?
a) Differentiation
b) Accretion
c) Erosion
d) Subduction
b) Accretion
Explanation: Accretion is the process where particles of gas, dust, and rock collide and combine to form larger bodies, eventually leading to planet formation.
What are the two main layers that Earth differentiates into after accretion?
a) Oceanic crust and continental crust
b) Core and mantle
c) Atmosphere and hydrosphere
d) Lithosphere and asthenosphere
b) Core and mantle
Explanation: After accretion, Earth undergoes differentiation, resulting in the formation of a dense metallic core and a lighter silicate-rich mantle.
How old is Earth, based on radiometric dating of meteorites?
a) 4.0 billion years
b) 4.5 billion years
c) 5.0 billion years
d) 3.5 billion years
b) 4.5 billion years
Explanation: Radiometric dating of meteorites shows that Earth formed approximately 4.55 billion years ago, a figure that has remained consistent with scientific findings.
