Progress Exams - Tectonics and Coasts Flashcards
Key topics covered on the progress exams
Name two ways that high tech monitoring can be used to minimise the risk from a Tsunamis.
- Network of sensors detect the tsunami
- Communications infrastructure alert coastal areas
Three evaluations of tsunami management
- Elderly don’t have access to phones / internet
- only alert when a tsunami has been caused by an earthquake
- Weak governance results in a failure to alert the population
Name three management strategies that can be used to detect a volcanic eruption
- Don’t normally erupt without warning
- Small earthquakes monitored by seismometers
- Swelling / bulge on the ground surface appears first
State two evaluations of the management of volcanic eruptions
- Good governance and development is needed to maintain equipment
- Some volcanoes erupt with no warning
What does the Park’s model show?
Compares response curve of hazard events
State the four stages of the Park’s model
Pre-disaster, Relief, Rehabilitation, Reconstruction
What is the evaluation for the Park’s model?
Does not consider social, environmental or political development
What happens in the pre-disaster stage of the Park’s model?
Normal quality of life - attempts to prevent / prepare
What happens in the relief stage of the Park’s model?
Medical relief is priority but quality of life improved slowly
What happens in the rehabilitation stage of the Park’s model?
Groups try to return to normal - provide food water and shelter
What happens in the reconstruction stage of the park’s model?
Groups try to return to normal - provide food, water and shelter
What does the hazard management cycle show?
Different stages of managing hazards
What are the four stages of the hazard management cycle?
Mitigation, Preparation, Response and Recovery
What is the evaluation for the hazard management cycle?
Cycle may be too generic and not quantifiable
What does the ritcher scale measure?
Measurement of amplitude of a wave
What does the moment magnitude scale measure?
Describes the magnitude of energy released
What does the volcanic explosivity index show?
Calculated by height or eruption cloud + explosivity
State how magnitude is useful
LE
Shows a greater intensity magnitude results in more damage
But some large populations are able to absorb the impacts
State how speed of onset is useful
LE
A rapid speed means people are less prepared
For a really large hazard, there is no way to prepare
State how duration is useful
LE
A long duration means more disruption
Hazards can be ‘long’ but have a small magnitude
State how areal extent is useful
LE
Large area means more damage
Tsunamis contaminate water and soil
State how spatial predictability is useful
LE
More predictable means more preparation
High magnitude overwhelms preparations
State how frequency is useful
LE
Less frequent means more unexpected
More knowledge means increased prepardness
State the three policy options for coastal management?
Do nothing
Managed Realignment
Hold the line
What is hard engineering?
Man made, invasive structures that reduce flood risk at coast
What is soft engineering?
Works with nature to help protect the coastline
How do sea walls manage the coastline?
They are a concrete wall - a barrier at the coastline that requires constant maintenance
Where has sea walls and how long are they?
Hornsea and Bridlington
4.7Km
How do groynes manage the coastline?
They are vertical stone or timber fences at 90° to the coastline and prevent the process of longshore drift
Where has groynes and how much do they cost?
Holderness -> Hornsea
£150 for 2500m
What is beach nourishment?
The process of artificially replenishing sediment from the beach
How much does beach nourishment cost?
£2 million per Km
How does the replanting of mangroves manage the coastline?
Increases the deposition and traps sediment while reducing the wave height
Where has mangrove replanting?
Bangladesh
450 hectares
What is dredging?
The removal of sediment from a source of the coastal sediment cell
Beach starved of sediment and decreases in area
Where experienced dredging?
Hallsands, 1890’s dredging occurred to form a naval base - 1500 tonnes of sediment
Storm in 1917 destroyed the village
How much of Sundarban’s area is experiencing mangrove removal?
70%
How much is wave height reduced by a 100m belt of mangroves?
Wave height reduced by 40%
What do negative feedback loops do in the sediment cell?
Temporarily reduce rates of recession
State one negative feedback loop in the sediment cell
Blockfall
What may shift the dynamic equilibrium?
External forces impact sources, transfers and sinks of sediment
State one positive feedback loop in the sediment cell
Removal of vegetation from sand dunes
What does a positive feedback loop do to the rates of recession?
Increases recession rates exponetially
Name one type of vegetation in sand dunes
Marram Grass
Name a drift aligned feature
Spit
Name a swash aligned feature
Bayhead Beach
Describe how a spit forms
Wave action + longshore drift transport material along the coastline
Prevailing wind is at 30° to the beach
Swash transports sediment up the beach and backwash transports it back down
When the angle is over 30°, energy is dispersed / lost and sediment is deposited
Name one spit
Spurn Head, Holderness
Describe how a Bayhead Beach forms
Wave action, when waves are at 90° to the coastline constructive waves deposit the sediment
Wave refraction disperses the wave energy and erosion is concentrated on the headlands with the sediment deposited in the bay
State 2 ways that a coastline may experience economic losses from coastal recession
Homes -> inability to insure
Infrastructure
When did the South Devon Mainline collapse and what was the cost to repair?
February 2014
Cost £35 million to repair
How much did businesses in the South West lose due to the South Devon Mainline being down?
$60 million
How much was land in North Yorkshire valued at in 2015 by the environment agency?
£500,000 / hectare
Less valuable due to glacial boulder clay and cooler climate
How many UK properties does the Environment Agency predict will be lost to the sea by 2050?
800
State one social loss from coastal recession
Relocation and its impact on mental health
In 2050, how many UK homes will be AT RISK from coastal recession?
32,000 homes
How is relocation bad for mental health?
Move away from support and a significant change in lifestyle
How is climate change impacting the Maldives?
A 50cm sea level rise will result in 77% of land being lost
How will the Maldives’ economy be impacted by flooding?
Majority of industry is in tourism - with most resorts being only 100m from the coastline
Where has experienced rotational slumping?
Christchurch Bay - Barton on Sea
When does rockfall occur?
In consolidated rocks when the downslope force exceeds the resisting forces of friction
When did the Jurassic Coast experience rockfall?
April 2020
Where is the Jurassic Coast?
South Dorset
How much sediment fell from the Jurassic Coast?
300m of cliff weighing 4000 tonnes
Where does rockfall normally occur?
In slopes with an angle over 40°
What types of rocks are susceptible to chemical weathering?
Sedimentary rocks containing calcite
What is the of pH acid rain?
5.6 - Weak carbonic acid
What does the solution formed from acid rain create in rocks?
Grooves and Runnels
What are the two engineering categories for modifying a hazard?
Micro and Macro
What is micro engineering?
Strengthening individual buildings and structures against stress
What is macro engineering?
Large scale measures to protect whole communities
State one example of macro engineering
Land Use Zoning
State one way to modify an earthquake
Base Isolation Systems
How do base isolation systems work?
Built away from the ground on flexible pads and isolators
By what percentage do base isolators reduce damage from an earthquake?
80%
