Hazards Flashcards
What is a hazard?
a potential threat to human life and property caused by an event
how is a hazard different to a disaster?
a disaster occurs when a vulnerable population is exposed to a hazard, causing significant disruption
how does experience affect hazard perception?
those with more experience may better understand hazards, but some may develop an optimistic outlook, thinking hazards wont repeat
what are hydrometeorological hazards?
hazards that are both atmospheric and hydrological, such as tropical storms
what are the three main types of geographical hazard?
- geophysical (land processes, tectonics)
- atmospheric (weather systems)
- hydrological (water bodies/ movement)
how can religion and beliefs influence hazard perception
some may see hazards as part of a divine plan
how does wealth affect hazard perception?
wealthier people may perceive hazards as smaller due to less vulnerability, but may also see greater financial risks
how does education affect hazard perception?
more educated individuals may understand the full effects of a hazard leading them to take precautions
example of a geophysical hazard
- volcanic eruptions
how does mobility influence hazard perception?
those with limited mobility may perceive hazards as greater threats as they cannot escape
example of an atmospheric hazard
- wildfires
example of a hydrological hazard
- floods
what is fatalism in the context of hazards?
the belief that hazards are uncontrollable natural events and any losses should be accepted
what is prediction in hazard response
using scientific research and past events to anticipate when a hazard will occur, allowing for warnings and prevention
what is mitigation in hazard response?
strategies carried out to lessen the severity of a hazard, such as using sandbags dooring floods
what is adaptation in hazard response?
adjusting lifestyle choices to reduce vulnerability, such as building earthquake proof houses
what is risk sharing in hazard response?
a community collectively investing in strategies to mitigate the impact of future hazards, like insurance in new zeland
how does hazard incidence affect human response?
low incidence hazards may have fewer management strategies in place and may be harder to predict
how does hazard distribution affect human response?
high distribution areas are likely to have more management strategies in place
how does prediction help reduce hazard impacts?
allows for warnings, like predicting wildfires from climate indicators
what is the difference between magnitude and intensity?
magnitude is the definable size of of a hazard, while intensity refers to the effects on people
how does economic development influence hazard response?
wealthier areas are more likely to have mitigation strategies, while less developed areas may experience worse effects from the same hazard
what challenges can HICs experience in hazard preparedness?
- resource limitations in multi hazard environments, like Canada’s limited response to tsunamis due to its focus on wildfires
what happens in stage one of the park model?
relief
- immediate local response
- medical aid
- foreign aid
what is the park model?
a graphical representation of human responses to hazards, showing recovery stages after a hazard, including the speed and depth of deterioration and recovery
what happens in stage 2 of the park model?
rehabilitation
- services are restored
- temporary shelters and hospitals
what happens in stage 3 of the park model?
reconstruction:
- restoring the area to the same or a better quality of life
- mitigation
how does the park model compare different hazards?
shows that more catastrophic hazards have steeper curves and slower recovery times
what is the hazard management cycle?
outlines stages of response to hazards: preparedness, response, recovery and mitigation
what are the limitations of hazard models like the park model?
- may not accurately represent the responses to all hazards
- may not account for factors such as development level or intensity
Structure of the earth- Inner core
- solid ball of iron/ nickel
-very hot due to pressure and radioactive decay
Structure of the earth- outer core
- semi molten
- iron/ nickel
Structure of the earth- mantle
- mainly solid rock
- high in silicon
-top layer (asthenosphere) is where convection currents occur
Structure of the earth- asthenosphere
- semi- molten layer that constantly moves due to convection currents
Structure of the earth- lithosphere
- broken into plates
- majority within the mantle
-the top is the earths crust
Structure of the earth- crust
- thin top of the lithosphere
-oceanic crust: dense, destroyed by plate movement - continental crust: less dense
what causes convection currents?
heat from the inner core rises through the mantle, making magma less dense. The magma cools becomes denser and sinks, creating a continuous loop
Plate tectonic theory
the lithosphere is broken into tectonic plates that move due to convection currents in the asthenosphere
what are the three main types of plate boundaries?
Destructive:
- move towards each other
Constructive:
- move away from each other
Conservative:
- move parallel to each other
what happens at a destructive plate boundary ( continental and oceanic)
- denser oceanic plate subducts below the continental plate, forming deep ocean trenches and fold mountains
- subducted oceanic crust melts, creating pressure that leads to volcanoes
what happens at a destructive plate boundary between two oceanic plates?
- the heavier plate subducts, forming ocean trenches and fold mountains
- underwater volcanoes form new land
what happens at a destructive plate boundary (two continental)
- no subduction occurs but pressure builds, causing fold mountains
what happens at a constructive plate boundary between two oceanic plates?
- magma rises between the separating plates , forming new land (sea floor spreading)
- less explosive underwater volcanoes as magma rises
what is sea floor spreading?
- the formation of new oceanic crust as magma fills gaps between separating plates
how is sea floor spreading evidenced?
- paleomagnetism shows symmetrical bands of rock with alternating magnetic polarity as proof of plate movment
what happens at a constructive plate boundary (continental and continental)
- land is forced apart, creating rift valleys
- volcanoes can form
What is ridge push?
- gravity acts on the slope created by separating plates, pushing them further apart and widening the gap
what is slab pull?
a subducting plate pulls the rest of the plate with it into the mantle, causing further subduction
what happens at a conservative plate boundary
- plates move parallel to each other in different directions or speeds
- no landforms but pressure can cause fault lines
what are lava flows?
- vary in speed depending on viscosity
- silica makes lava viscous and slow
- common in explosive eruptions
what are hotspots?
areas of of volcanic activity unrelated to plate boundaries where magma plumes rise and burn through the crust, creating volcanoes and islands i.e. Hawaii
what are lahars?
- mudflows caused by melting ice during eruptions
- can flow rapidly and cause significant damage
what are toxic gasses in volcanic eruptions
- gases such as CO2 can be released and pose a lethal risk
what causes acid rain during volcanic eruptions?
- gases like sulfur dioxide are released into the atmosphere, causing acid rain
what is the difference between explosive and effusive eruptions?
- Explosive eruptions have high magnitude and release more tephra, while effusive eruptions are calmer and lower magnitude.
what are pyroclastic flows
- clouds of hot ash and gas that travel at high speeds
- up to 430mph
What are the primary effects of volcanic hazards on the environment?
- Ecosystems damaged
- wildlife may be killed due to various volcanic hazards.
what is the ring of fire?
- 25,000 mile belt around the pacific ocean known for high volcanic and earthquake activity
what is the volcanic explosivity index (VEI)?
- a logarithmic scale measuring the power of volcanic eruptions based on factors such as tephra volume and eruption height
What are the primary social effects of volcanic hazards?
- People killed
- homes destroyed by lava or pyroclastic flows
- key government buildings may be damaged.
What are the secondary economic effects of volcanic hazards?
- Jobs lost
- businesses and industries disrupted
- financial benefits from tourism.
How can volcanic hazards be managed through preparedness?
- Monitoring
- evacuation procedures
- educating people in risk areas can reduce impacts
What are the secondary social effects of volcanic hazards?
- Fires
- homelessness
- conflicts over government response and food shortages
How can volcanic hazards be managed through adaptation?
- Move away from at-risk areas
- strengthen buildings
- capitalize on tourism opportunities
Can volcanic eruptions be predicted?
- seismic activity and gas release can indicate an eruption
- exact predictions are not possible
What causes plates to become stuck during movement?
- Plates can become stuck due to friction between their irregularities, building up pressure until the plates give way, releasing seismic waves
How does pressure build up between plates?
- Plates become stuck, but convection currents continue to push, building pressure until the plates move suddenly, causing seismic waves.
What is the focus and epicenter of an earthquake?
- The focus is the point underground where the earthquake originates
- The epicenter is the point on the Earth’s surface directly above the focus.
How does the depth of focus affect earthquake magnitude?
- Shallow focuses (e.g., at conservative boundaries) produce stronger seismic waves near the epicenter, while deeper focuses spread the waves over a larger area.
What are shockwaves in earthquakes?
he ground to vibrate.
- Shockwaves (or seismic waves) occur when plates release built-up pressure, transferring potential energy into kinetic energy, causing the ground to vibrate.
How is seismicity measured?
- logarithmic Richter Scale (strength of seismic waves) and the Modified Mercalli Intensity Scale (level of destruction).
What is a tsunami, and how does it form during an earthquake?
- A tsunami occurs when an oceanic crust is jolted, displacing water above it. The waves travel fast but low, gaining height as they reach shallower coastal waters.
What is liquefaction?
- Liquefaction occurs when saturated soil is shaken during an earthquake, making it behave like a liquid, weakening it and causing the ground to subside under weight.
How does a tsunami’s height increase as it approaches the coast?
- As the tsunami reaches the coast, friction between the seabed and the waves slows them down, causing the wave height to increase, creating a large wall of water
