Hazards (without case studies) Flashcards
The concept of hazards in a geographical context
-Disaster description
-When a hazard causes a significant impact on a vulnerable population-> serious, widespread, social, economic, environmental losses exceeding the ability of the community to cope
The concept of hazards in a geographical context
-Hazard description
-A perceived natural/geophysical event that has the potential to threaten life and property damage
The concept of hazards in a geographical context
-Resilience
-The ability of a community to cope with, and recover from, the effects of a hazard in a timely and efficient manner; including through preservation and restoration of basic structures
The concept of hazards in a geographical context
-Risk description
-The probability of a hazard occurring, creating loss of lives and/or livelihoods
The concept of hazards in a geographical context
-Risk assessment description
-The likelihood of harm and damage and the anticipation of the type and scale of these
The concept of hazards in a geographical context
-Vulnerability
-The reduced capacity of an individual or group to anticipate, cope with, resist and recover from the impact of natural or man-made hazards
The concept of hazards in a geographical context
-Description of geomorphic hazards
- Geomorphic= Changes in land shape
- Hazard event= Landslide
The concept of hazards in a geographical context
-Description of atmospheric hazards
- Atmospheric=storm hazards
- Hazard events= Tropical storms (typhoon), extra-tropical storm (over UK)
The concept of hazards in a geographical context
-Description of hydrological hazards
- Hydrological= water/weather extremes
- Hazard events= Drought
The concept of hazards in a geographical context
-Description of geophysical hazards
- Geophysical= All tectonic hazards
- Hazard events= Earthquake, tsunami
The concept of hazards in a geographical context
-Description of biohazards
Biohazards= Hazards associated with plant and animal life
Hazard events= Wildfires
The concept of hazards in a geographical context
-Hazard perceptions and concepts
Economic:
-If a country is poor/poorly developed, they will struggle to cope when the hazard hits (vice versa for developed countries)
Social:
-Poorer people who live in high density areas will suffer when a hazard hits because the infrastructure will not protect them. People in rural areas may become affected and could get cut off from aid from local services
Political:
-If the government is organised and sets out emergency plans and routes then the affects will be decreased
Technological:
-If there are accurate predictions from scientists, then local services can provide safety measures and evacuation paths in good time
The concept of hazards in a geographical context
-Factors that affect how a community responds to a hazard
Human factors:
-Fatalism, prediction, adaptation, risk sharing, mitigation
Physical factors:
-Physical vulnerability, social vulnerability, hazard exposure
The concept of hazards in a geographical context
-Park’s disaster-response model
- The Park model is also known as the disaster response curve
- It’s aim is it show the effects of a hazard on quality of life over a sequence of time
- There are 3 outcomes at the end: improvement, return to normality and deterioration
- The x- axis is time and the y-axis is quality of life
The concept of hazards in a geographical context
-Disaster management cycle
- The are 4 main components: mitigation, preparedness, response and recovery
- The DMC aims to reduce, or avoid, the potential losses from hazards, assure prompt and appropriate assistance to victims of disaster, and achieve raid and effective recovery
- The 3 stages are: pre-disaster, disaster occurrence and post-disaster
The concept of hazards in a geographical context
-Socio-natural disasters
-Socio-natural disasters are both natural and man-made e.g. fires, droughts and floods
Plate tectonics
-Asthenosphere
Layer of the Earth immediately below the lithosphere and is hotter and weaker than the lithosphere
Plate tectonics
-Collision zone
A type of convergent margin in which two continents or island arcs have collided
Plate tectonics
-Convection currents
Heat generated by the breakdown of minerals in the mantle which is redistributed by by currents that rise at mid oceanic ridges
Plate tectonics
-Fault line
A long crack in the surface of the Earth
Plate tectonics
-Fold mountain
Are created where two or more of Earth’s tectonic plates are pushed together
Plate tectonics
-Gravitational sliding (or ridge push)
A proposed driving force for plate motion in plate tectonics
Plate tectonics
-Island arcs
A curving chain of volcanic islands occurring around the margin of ocean basins
Plate tectonics
-Lithosphere
The outer cool, rigid and brittle layer of the Earth
Plate tectonics
-Mantle
The zone lying between the Earth’s crust and core
Plate tectonics
-Oceanic ridges
An underwater mountain range, formed by plate tectonics
Plate tectonics
-Rift valley
A lowland region that forms where Earth’s tectonic plates move apart, or rift
Plate tectonics
-Slab pull
Is part of the motion of tectonic plate caused by it’s subduction
Plate tectonics
-Subduction zone
Where Earth’s tectonic plates dive back into the mantle, at rates of a few cm a year
Plate tectonics
-Plate tectonic theory of crustal evolution
- The theory of plate tectonics states that the Earth’s solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper part of the mantle
- The data and observations by the Tharp-Heezen map became critical factors in the acceptance of the the theory because it revealed that the ocean floor wasn’t flat and it was due to sea-floor spreading
Plate tectonics
-Hot spots and magma plumes
- A hot spot is an area on Earth over a mantle plume or an area under the rocky outer layer of Earth. It is separated in the lower mantle and go up to 1000km below the Earth’s surface. Example= Hawaiian islands
- Magma plumes are areas of hot, upwelling mantle. Magma generated by the hot spot rises through the rigid plates of the lithosphere and produces low viscosity volcanoes at the Earth’s surface
Plate tectonics
-Sea-floor spreading
- Sea-floor spreading occurs at divergent plate boundaries
- As tectonic plates slowly move away from each other, the heat from the mantle makes the the crust more plastic
- The less dense material rises, often forming a mountain on the sea floor
Plate tectonics
-Convection currents
- Heat rising and falling inside the mantle creates convection currents generated by radioactive decay in the core
- The convection currents move the plates. Where convection currents diverge near the Earth’s crust, plates move apart. Where convection currents converge, plates move towards each other.
Plate tectonics
-Destructive plate margins
- At a destructive boundary, the plates are moving towards each other and they usually involve the continental plate and the oceanic plate
- The oceanic plate is denser than the continental plate and as they move together, the oceanic plate is forced underneath the continental plate
- The point at which this happens is called the subduction zone
- When the oceanic plate is forced below the continental plate, it melts to form magma and earthquakes are triggered
- As the plate is forced down, there will be a deep gap under the sea which is known as an ocean trench
Plate tectonics
-Constructive plate margins
- At constructive plate margins, the plates move apart from one another.
- When this happens, the magma from the mantle rises up to make (or construct) new land in the form of a shield volcano
- The movement of the plates over the mantle can cause earthquakes
Plate tectonics
-Conservative plate margins
- At a conservative plate margin, the plates move past each other or are side by side moving at different speeds
- As the plates move, friction occurs and plates become stuck. Pressure builds up because the plates are still trying to move
- When the pressure is released, it sends out huge amounts of energy, causing an earthquake
- The earthquakes at a conservative plate boundary can be very destructive as they occur close to the Earth’s surface
- There are no volcanoes at a conservative plate margin
Plate tectonics
-Characteristic processes: seismicity
- Seismicity refers to the frequency of earthquake activity in an area
- Earthquakes follow distinct patterns of distribution that follow fault line zones and reactivated fault zones
- The most violent earthquakes occur at low depths associated with subductive plates at convergent margins
Plate tectonics
-Characteristic processes: vulcanicity
- Vulcanicity refers to all the various ways by which molten rock and gasses are forced into the Earth and onto it’s surface
- It includes volcanic eruptions which lead to the formation of volcanoes, lava plateaus and geysers