Hazards Flashcards
What is a Geophysical hazard?
a Hazard triggered by internal processes, such as Tectonic movement.
What is a Hydro- Metrological hazard?
A hazard triggered by water, and anything associated with weather patterns.
What does the Degg’s model say?
A vulnerable population and a hazardous event, creates a disaster.
Why is hazard risk changing?
frequency is increasing due to climate change
countries are less able to cope, due to poverty and urbanisation.
what is the Hazard management cycle?
Pre-disaster
Responses
Post disaster
mitigation
What is fatalism?
The concept that forms in areas at high risk, where if an event is going to occur then it can’t be changed.
How does a volcano form?
The denser oceanic crust is subducted under the continental crust, creating a deep ocean crust.
magma rises through the lithosphere and creates a volcano.
The oceanic plate continues descend in a convectional cell.
What are the four types of plate margins?
Destructive- Denser plate is subducted.
Constructive- Plates mover past each other
Conservative- Plates move apart.
Collision- Plates collide
What are the two types of plate movement?
Ridge Push
Slab Pull
What determines the destructivity of a volcano?
The viscosity of its magma.
Low- runny magma and shallow sided volcano
high- sticky thick magma and steep sided volcano
What affects viscosity?
Temperature- thinner
Silica content- thicker
Dissolved gasses- thinner
What are the primary impacts of a Volcano?
Ash
Lava
Pyroclastic flows
Gas Lava bombs
What are secondary impacts of a Volcano?
Acid rain
climate change
Tsunami
Lahar (mudflow)
Flooding
What is a pyroclastic flow?
Move at very rapid speeds, can be a caused by dome collapsing or a collapse of volcanic column.
Can also be known as ‘Nuee Ardente’
How are earthquakes measured?
Mercalli scale- how much damage has been caused
Moment of magnitude- Based on the total moment (the distance a fault moved)
Richter scale- measure energy of an earthquake
What is the benioff zone?
found along a subduction zone, results from the oceanic crust forced under the continental crust.
What are the two types of seismic waves?
S- waves (Secondary waves)
P- waves (Primary waves)
How doe P&S waves move?
Surface waves- long waves that take longer to complete a cycle of motion.
Rayleigh waves- Have a rolling motion, produce both horizontal and vertical movements
Love waves- fast and shake the ground at right angles
What are primary impacts of earthquakes?
Ground displacement
Falling buildings
What are secondary impacts of earthquakes?
Liquefaction
Landslides
Tsunamis
Fires
What is Liquefaction?
The shaken loose sediment draws up water, this liquifies the surface. This then begins to solidify quickly, and becomes like quicksand.
What are short term responses to earthquakes?
Emergency aid
Search and rescue
medical care
shelters
being prepared for after shocks
What are long term responses to earthquakes?
Rebuilding infrastructure
mitigating against further quakes
educating the people
What are short term responses to volcanoes?
Emergency rescue
evacuation
Providing Aid
What are long term responses to Volcanoes?
Restoring Power and water
Rebuilding Infrastructure
Mitigating against future Volcanic events
What defines a hazard?
A threat of substantial loss or impact to life. Similarly, damage done to property through a natural event.
What is the Park model?
It demonstrates the relationship between hazards and the human response to them.
In the Parks model, what are the three phases of response?
Relief
Rehabilitation
Reconstruction
What are the phases of the hazard management Cycle?
Preparedness
Response to the Hazard event
Recovery post damage
Mitigate against any more hazard events.
What is Plate Tectonic Theory?
That the continental drift is caused by the movement of tectonic plates, through discovering that the newest rocks were found in the centre of the Atlantic Ocean.
What is Ridge Push?
The weight of gravity pushes the older part of the plate to the front, acting as a push.
How does a Mid-Ocean ridge form?
Divergence within the ocean, forms chains of submerged mountain ridges that stretch kilometres. Within the Mid- Ocean Ridges deep rift valleys occur, which continue to widen due to rising magma.
What is Slab-pull?
After subduction, the lithosphere sinks into the mantle, with its weight helping to “pull” causing it to melt.
What is a Rift Valley?
Valleys that are formed when the lithosphere stretches, causing it to fracture into sets of parallel faults and collapsing the land in-between them.
Where can an example of a Rift Valley be found?
East Africa’s Great rift valley. It extends 5,950km.
What occurs when at a destructive plate margin?
It subducts under the more dense continental plate. The point of the collision is marked by a Deep Ocean Trench.
Where can a example of an Ocean Trench be found?
Marianas Trench- Pacific Ocean
What is the name of the area where the crust melts?
Benioff Zone
What is by product of a destructive plate margin?
Fold mountains, as the continental plate scrunches up.
What is the name for a volcano found at a destructive plate boundary?
Andesitic Volcano.
What is the Asthenosphere?
The zone of the mantle that lies between the mantle and the lithosphere, usually hotter than th mantle.
What are a by product of two continental plates meeting?
Fold mountains.
What occurs at conservative plate boundaries?
Powerful earthquakes.
Where can a Conservative plate boundary be found?
San Andrea’s fault- California.