Geography Natural hazards Flashcards
Natural HAzards
What is a Hazard?
A hazard is a potential threat to human life and property caused by an event ; an event is only a hazard when it is a threat to human life.
What is a multi-hazardous environment?
Where many hazards may be present and where these may occur simultaneously.
What are the three major types of geographical hazards?
Geophysical - Caused by land processes ( tectonic plates) e.g. Volcanoe
Atmospheric - Caused by atmospheric proceesses and conditions by weather e.g. wildfires
Hydrological - caused by water bodies and movement e.g. floods
What is hazard preception and how do economy and experience affect it?
A persons view on how dangerous hazards are and the risk they pose. Wealthier people will be less frightful of a hazard compared to poorer people but can have a bigger loss. Experience can play a role as someone experienced with a certain hazard will have more knowledge on what to do.
What are human responses to hazards?
Prediction ( Scienctific research), Adaptation, Mitigation, Management and Risk Sharing.
What is Mitigation?
Strategies carried out to lessen the severity of a hazard (e.g. sandbags to offset impact of flooding).
What is Fatalism?
The viewpoint that hazards are uncontrollable natural events, and any losses should be accepted as there is nothing that can be done to stop them.
What is the Park Model?
The Park Model is a graphical representation of human responses to hazards, showing the steps carried out in the recovery after a hazard, giving a rough indication of time.
What is the hazard management cycle and what does it show?
The Hazard Management Cycle is a systematic process that aims to reduce the impact of disasters by means of planning and response, learning and adaptation after the event.
How is the earth structured?
Lithosphere (Crust), Ashenosphere, Mantle, Outer Core, Inner Core
What energy sources are found internally in the earth?
Renewable sources of energy including the heat from gravity and nuclear or radioactive decay.
What is ridge push?
Ridge push is a tectonic process involving the gravitational force that causes an oceanic plate to move away from a mid-ocean ridge.
What is slab pull?
Slab pull is a geophysical process that refers to the force exerted by a subducting tectonic plate as it sinks into the mantle.
What is Sea-floor spreading?
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity.
What are convection currents?
Convection currents are heat-driven cycles that move energy from one location to another, primarily occurring in gases and liquids caused by variations of temperature and density.
What happens to the plates at each boundary Constructive/Destructive/Conservative?
Constructive - Plates move away from each other.
Destructive - The plates move towards each other.
Conservative - Slide past each other, get stuck and eventually slip.
What characteristics and landforms occur at Constructive plate boundaries?
Deep sea trenches, Rift Valleys, Ocean Ridges, shield volcanoes.
what landforms/characteristics occur at destructive plate boundaries?
Destructive plate boundary occurs when an oceanic plate is forced under a continental plate creating fold Mountains and Oceanic trenches.
What is seismicity?
The occurrence or frequency of earthquakes in a region.
What is vulcanicity?
Molten rock/magma erupting onto the surface of the Earth or a solid-surface planet, moon or asteroid.
What are young fold mountains/how are they formed?
Young fold mountains are mountains that are formed by the folding of the earth’s crust due to tectonic activity and are less than 15 million years old.
What are rift valleys/ how are they formed?
Rift valleys are elongated lowland regions that form due to geological processes such as extensional tectonics, faulting and pulling apart of the lithosphere. e.g. East African rift
What are ocean ridges/how are they formed?
An oceanic ridge system is formed during tectonic activity whereby tectonic plates move apart and create gaps.
What are island arcs/how are they formed?
An island arc is a chain or group of islands that forms from volcanic activity along a subduction zone.
How/Why do volcanoes erupt?
When enough magma builds up in the magma chamber, it forces its way up to the surface and erupts ; eruptions can also be triggered by human or natural factors.
What are magma plumes?
Magma plumes are areas of hot, upwelling mantle pushed by convection currents.
How are volcanoes distributed globally?
Most volcanoes occur on plate margins in linear clusters at destructive margins (e.g. South American Plate) & constructive plate margins (e.g. Mid-Atlantic Ridge).
What are the natural hazards that can occur with volcanic events?
lava flows, mudflows, pyroclastic flows, acid rain, tephra.
What are pyroclastic flows?
A pyroclastic flow is a fast-moving current of hot gas and volcanic matter that flows along the ground away from a volcano usually >800 °C/ average speeds of 100 km/h - 700km/h.
What is tephra?
Rock fragments and particles ejected by a volcanic eruption.
What are Social/Economic/Political impacts of a volcano?
Social - Roads can be blocked and buildings can be destroyed, airlines denied flight.
Economic - Cost of damages / Many businesses can shut down for a long time, tourism can be paused.
Political - World Leaders cannot fly as ash will spread and prevent flying and pressure to respond quickly to needs.
What are primary impacts of volcanoes?
When volcanoes erupt they can spew hot, dangerous gases, ash and lava causing disastrous loss of life and property, especially in heavily populated areas.
What are secondary impacts of a volcano?
Roads can become blocked by solidified lava flows and airports can be shutdown making it difficult to travel around.
Case Study: What were the impacts and responses to the Iceland 2010 volcanic eruption?
- Ten million passengers were affected, and more than 100,000 flights were cancelled all over Europe.
- The cost to the aviation industry was estimated to be over £1.2 billion.
- The volcano released approximately 150,000 tonnes of CO2 each day, or approximately 4.5 million tonnes of carbon dioxide by 19 April 2010.
Which plates create earthquakes?
Most seismic activity occurs at three types of plate boundaries—divergent, convergent, and transform.
How are earthquakes distributed globally?
80%+ of large earthquakes occur around the edges of the Pacific Ocean, known as the ‘Ring of Fire’; this where the Pacific plate is being subducted beneath the surrounding plates.
How is the magnitude of earthquakes measured?
They are measured by using seismometers and then are measured on The Richter scale then the intensity is measured on The Mercalli scale.
How is the magnitude of a volcano measured?
Volume of products and eruption cloud height are studied then used for the VEI (Volcanic explosivity Index)
What are forms of seismic hazards?
Earthquakes, tsunamis, liquefaction and landslides.
What are the Social/Economic/Environmental impacts of earthquakes?
Social - Many families become seperated/lack of access to food and water.
Economic - Cost of damages, businesses closed/ destroyed.
Environmental - Disruption of soil and vegetation, soil Liquefactions.
What are the primary impacts of an earthquake?
The primary effects of an earthquake include ground shaking, ground rupture, and landslides.
What are secondary impacts of an earthquake?
Secondary effects may include subsidance, tsunamis, fires, contamination of water supplies, gas leaks, and power outages.
Case Study: What were the impacts and responses to the Haiti Earthquake 2010?
The earthquake was 7 on the richter scale left more than 1.5 million people homeless, killed 222,570 people and injured 300,000. Many countries responded to appeals for aid with rescue and medical teams, cost of damage 14 billion US.
What are wildfires?
A fire that starts in a wild area such as a forest spreading rapidly and causing great damage.
What conditions help wildfires?
Dry seasons resulting in dry plants and high temperatures but also wind helping the spreading.
What are human and natural causes of fire?
Human - Slash and burning, discarded cigarettes, campfires.
Natural - Lightning and high temperatures
What are the Social/Economic/Environmental impacts of wildfires?
Social - Evacuation and homes destroyed
Economic - Cost of damage (agriculture) and firefighters
Environmental - Animal habitats destroyed and lots of CO2 emitted from the flames.
What are the primary impacts of wildfires?
Disruption to transport, infrastructure/surrounding businesses and smoke threatening health.
What are secondary impacts of wildfires?
Burnt areas become prone to flash floods, soil erosion, landslides and desertification.
Case Study: What are the impacts and responses to the Alberta, Fort Mcmurray wildfire 2016?
- Estimated damage cost of C$9.9 billion (US$7.61 billion)
- 500 species of wildlife lost their habitats or were in danger due to the fire.
- 90,000 forced to evacuate homes in Fort Mcmurray.
What are tropical storms?
A tropical cyclone is a rapidly rotating storm system with a low-pressure area with strong winds and terential rain.
How are tropical storms formed?
They’re formed by sea temperatures of 27°C or more and converging winds on the ocean surface forcing air to rise and form storm clouds.
What hazards do tropical storms trigger?
High winds, storm surges, coastal flooding, river flooding and landslides.
What is the global distribution of tropical storms?
Most tropical storms form 5–15° north and south of the Equator also more tropical storms occur in the northern hemisphere.
What are the Social/Economic/Environmental impacts of tropical storms?
Social - People left homeless and lack of clean water
Economic - Unemployment caused by businesses being damaged
Environmental - Coastal habitats like beaches and mangroves can be damaged by storm surge floods.
What are primary impacts of tropical storms?
Immediate effects of strong winds, high rainfall and storm surges.
What are secondary impacts of tropical storms?
Landslides which can cause people to become homeless and can block roads and railways.
LIC Tropical Storm Case Study: What are the impacts and responses to Typhoon Haiyan 2013?
The typhoon damaged 1.1 million houses destroyed, 33 million coconut trees and pushed approximately 2.3 million people into poverty. Overall damage is estimated at $13 billion.
HIC Tropical Storm Case Study: What are the impacts and responses to Hurricane Sandy?
346,000 houses were damaged/destroyed in New Jersey, $20Billion damage to Subway stations in New York . More than 18,000 flights were cancelled.
Why are LICs more affected by hazards than HICs?
HICs have more money to spend on hazard proof buildings and technology to predict hazards but also for recovery whilst LICs don’t have funds for technology and have lower economies to recover from hazards.
