Exam Q's PAPER 1 Flashcards
(TECTONICS)
Explain 2 secondary hazards (liquefaction + landslides) caused by EQ’s?
- Fires can be started by broken gas lines and power lines
* Tsunamis - undersea EQ’s, occurs at plate boundaries & displaces water
Explain tectonic hazards that may result from volcanic activity (6 marks)
- Tephra are tiny particles of rock and natural glass blasted into the air by volcanic eruptions
- Gas eruptions occurs when magma contains dissolved gasses, and these are released from the liquid magma as it reaches the surface
- Lahars are caused by rain mixing with either ash on steep side of a volcano creating a great mudflow, or ash mixing with rain.
- Jokulhlaups occurs when the volcano beneath an ice cap erupts, and large amounts of ice above it melts
- Volcanoes can trigger tsunamis
Assess whether the development and governance are the most important factors in understanding the scale of tectonic disasters. (12 marks)
- If disasters occur in developed countries, there will be less social impacts. However, the economic impact might be much higher because of damage to critical infrastructure. Poor development and governance is often caused by high pop density (high levels of urbanisation) &/our isolation from centre of gov.
- Its easier for developed countries to act in response to disasters. However, sometimes their actions in response to some hazards (e.g. ash clouds caused global trade disruption)
- Also, physical geography (e.g. direction of ash fall, tsunami wave propagation)
- Serious damage in developing world can cause the wipe out of entire communities. But, it can also refocus communities to increase resilience.
(COASTS)
Factors which affect coastal sediment transport:
Wind direction, wave energy, rides & currents, & sediment size.
Explain 2 coastal depositional processes (4 marks)
•LSD, constrictive waves have stronger swash & create beaches/spits/offshore bars.
•Obstacles on the beach - marram grass creates low energy zones where
sand is deposited.
Explain the factors which create an erosion all coastline. (6 marks)
- Types of waves present - constructive or destructive
- Rock hardness, e.g. hard or soft rock
- Geological orientation - discordant coasts have different rates of erosion, resulting in headlands & bags. Headlands concentrate wave energy (refraction) resulting in more complex erosional features.
- Erosional processes = hydraulic action/attrition/abrasion. Some mechanical processes (solution + saltation) expose the coastline to wave & sun-aerial processes.
- Rock layers - differences within the cliff face affects level of resistance, different rates of erosion over time can cause landslides.
- When cliffs are worn back, a shore (wave-cut) platform is left, which can be covered by sea at low-tide, resulting in further abrasion.
Assess whether sustainable management schemes are always most appropriate for managing risks to coastline (12 marks)
- Sustainable schemes relate to using soft engineering to protect coastline, as opposed to hard. Generally, they are cheaper, but do need some maintenance. Risks affecting the coastline may include: storms, sea level rise, and dredging.
- When deciding if it’s appropriate to use certain schemes you must whey up: effects of coastal retreat, Econ losses and social losses (livelihood)
- Appropriate use of hard + soft requires specialist stakeholders who understand principles of ICZM & littoral drift and sediment cells.
(TECTONICS)
Explain why the number of reported EQ’s has risen since 1960? (4 marks)
- Due to an increase in the number of recording stations which means more EQ’s are detected which previously might have been missed in remote areas.
- Higher population densities, which leads to more reporting because areas are better ‘covered’.
•Also better detection equipment so smaller magnitude EQ’s are detected which previously might have been missed.
Explain the causes of tsunamis (6 marks)
- Caused by displacement of water
- EQ’s displace water when movement causes the seabed to thrust upwards undersea. Landslides displace water when material falls from a continental shelf to the sea bed.
- Volcanic eruptions displace water
- The displaced water becomes tsunami waves
- In shallower water, the friction between the tsunami wave and the seabed increases & the tsunami wave slows down, decreasing wavelength but increasing height.
Assess the significance of EQ hazard profiles in relation to the effectiveness of management strategies (12 marks)
•Hazard profiles relate to the magnitude, speed of onset, areal extent, duration, frequency and spatial predictability of EQ’s.
•Management strategies include modifying event through land-use
Zoning and hazard-resistant design.
•Management strategies include modifying vulnerability & resilience of a population through education &
Community preparedness
•Management strategies include modifying loss which includes emergency, short+long term aid & insurance & actions of affected
Communities themselves
•Magnitude of an EQ can be most
Important factor in determining success of modifying the event management strategies as even in MEDC that have invested heavily
•In contrast, smaller EQ’s can be managed more effectively, even with basic aesismic buildings such as beans & columns
•Frequency of EQ’s is also a key factor
In determining the success of modifying the vulnerability of the pop as the more frequent the EQ, the more likely the community is likely to educated & aware of the hazard threat as demonstrated by relatively low impacts of San Fran 89’ & LA of
94’ EQ events showed
(COASTS)
1 weathering process that occurs at a coast
Abrasion, hydraulic action
Explain 2 processes in the formation of offshore bars (4 marks)
LSD - carries & deposits sediment at right angles to the coast
Destructive waves - deposit material in shallow sea beds
Explain how geological structure affects development of coastal landforms (6 marks)
Geological structure relates to if the coastline is concordant or discordant, or seaward or landward dip, & also the type of rock present - hard or soft rock?
•Concordant coasts are where the geology runs parallel to the coast and is associated with landforms such as coves + Dalmatian coastlines
•Moreover, depositional features such as spits are more likely to be forced in concordant coasts where LSD can operate.
•Whereas, discordant coastlines are where the geology runs at right angles to the coast & creates landforms such as bays and headlands reflecting variations in rock resistance.
•The horizontal bedding of resistant rocks such as sandstone leads
To vertical cliffs
•The exact profile of vertical cliffs can also be determined by the joint pattern pf rock, as well-jointed granite or limestone creates blocky profiles.
Assess the importance of Lithology in influencing the rate of coastal recession (12 marks)
Lithology refers to physical properties of a rock such as its resistance to erosion. The Lithology is how quickly it’s eroded. Hard rocks are resistant to weathering & erosion so a coastline made of granite (Lands end) will change slowly.
•Soft rocks (Limestone) are more susceptible to weathering + erosion & so a coastline made of chalk (Dorset) will change quickly.
•Concordant coasts have alternating layers of hard & soft rock that run parallel to coast. Hard rock acts as a protective barrier to softer rock behind. If hard rock is breached - can lead to a cove forming (Lulworth cove)
•On discordant, alternating layers of hard + soft are perpendicular to coast - cos the soft rock is exposed, its eroded faster than hard rock. This differential erosion leads to headlands & bays
•Bedding layers are layers of different rock, subject to tectonic forces that tilt & deform them so they dip at an angle. Angle of dip affects erosion & profile of resulting cliffs.
•Horizontal beds, produce steep cliffs with notches. A steep profile with softer rock beds, will be eroded to notches.
•Seaward dip, produce gentler cliffs that are less stable as material slides down in mass movements
Evaluate the relative importance of the human + physical geography of the coasts & characteristics of tsunami event in determining its impact (16 marks)
Physical geography: could relate to how close the coast is to the epicentre of the EQ, which triggers the tsunami.
•If the coastline is very close, as is the case for Myagi, then the impact will be very high, since the waves won’t have to travel very far to reach mainland
•Rocky coastlines & coastal plains (sandy or estuarine) have physical characteristics which can reduce or increase vulnerability to tsunamis.
•Characteristics of tsunami can be considered through magnitude, speed of onset, duration, and frequency
•Rocky coastlines with steep cliffs offer natural protection against tsunamis
•Whereas lowland areas are more vulnerable to tsunami as not only do they not have a cliffed coastline but cos of their easier access to coast they are more likely to have higher pop density —> bigger social impacts
