Tectonic Hazards Flashcards
What are the two main types of natural hazards?
- Geological Hazards
* Meteorological Hazards
What is the cause of Geological Hazards?
- Caused by land and tectonic processes
* E.g. volcanoes, earthquakes, landslides, avalanches
What is the cause of Meteorological Hazards?
- Caused by weather and climate
* E.g. tropical storms, heatwaves, cold spells, climate change
What are the factors affecting the Hazard Risk?
- Capacity to Cope
- Vulnerability
- Nature of Natural Hazards
What is a Hazard Risk?
Probability that a natural hazard occurs
How does Vulnerability affect the Hazard risk?
- More people in exposed area, greater probability they will be affected by a natural hazard - hazard risk higher
- E.g. City at base of volcano (Naples) very vulnerable to volcanic eruptions
How does Capacity to Cope affect the Hazard risk?
- The better population can cope w/ extreme event, the lower the threat
- If used to hazard then your resilient to hazard
- E.g. HICs more able to cope with flooding because they can afford flood defences, etc
What are the different type of Plate Margin?
- Destructive Margins
- Constructive Margins
- Conservative Margins
- Collision Plate Margins
What are Destructive Margins?
•2 plates moving towards eachother
What are Constructive Margins?
Two plates moving away from each other
What are Conservative Margins?
- Two plates are moving sideways past eachother
* Two plates moving in same direction but at different speeds
What are Collision Plate Margins?
•Two plates made from continental crust and move towards each other
How are Earthquakes caused?
- Tension that builds up at Plate Margins
* Plates jerk past each other, sending shock waves, these vibrations are the earthquake
How are Earthquakes measured?
- Moment magnitude scale
* Richter scale
What are Tsunamis and how are they caused?
- Series of enormous waves
* Caused when huge amounts of water get displaced
How can Earthquakes cause Tsunamis?
- Underwater earthquakes cause seabed to move, displaces water
- Waves spread out from epicentre of earthquake
- Shallow force earthquakes displace more water because they are closer to Earth surface = bigger tsunami
How are Volcanoes formed at Destructive Margins?
- Oceanic plate under continental plate because more dense
- Oceanic plate moves into mantle, where melted and destroyed
- Pool of magma forms
- Magma rises through cracks in vents
- Magma erupts on surface (lava)
- Forming volcano
How are Volcanoes formed at Constructive Margins?
- Magma rises up into gap created by plates moving apart
* Forming volcano
What are Composite Volcanoes?
- Occur at destructive plate margins
- Water reacts with Magma, creates gases, subducted crust erupts
- Ashy explosion, erupt andesitic lava (high silica content - thick/sticky)
- Lava can’t flow far so form steep-sides cone
What are Shield Volcanoes?
- Occur at hotspots or constructive plate margins
- Not explosive, only lava
- Erupt basaltic lava (low silica content - runny)
- Flow quickly and spreads over wide area so form low, gentle-sided volcano
What are the Primary Effects of Earthquakes?
- Bridges, buildings collapse - people injured from this
- Homes destroyed
- Roads, railways, airports damaged
- Electricity cables, gas, water pipes, communication networks damaged
What are the Secondary Effects of Earthquakes?
- Leaking gas ignited, start fire
- People homeless and could die
- Shortage of clean water/lack of sanitation - diseases spread
- Business destroyed - unemployment
- Trigger landslides/tsunamis - destroy more buildings - more deaths and injuries
What are the Immediate Responses to Earthquakes?
- Rescue trapped people
- Recover dead bodies to prevent diseases being spread
- Put our fires
- Set up temporary shelters
- Provide temporary supplies of water, food, electricity, gas, communication systems
- Foreign government send aid workers, supplies, equipment, financial donations
What are the Long-Term Responses to Earthquakes?
- Re-house people who lost home
- Repair/Rebuild damaged buildings,roads,railways,bridges
- Reconnect broken electricity, water
- Improve building regulations so resistant to damage from earthquakes
- Set up initiatives to help economic recovery
