Tectonic Hazards Flashcards
state the plates tectonic theory
the Earth’s crust is divided into slabs of rock called tectonic plates. These plates are made up of two types of crust; oceanic and continental - oceanic crust is thin and dense, whereas continental crust is thick and les dense
some people believe that convection currents in the mantle cause tectonic plates to move
describe the physical processes taking place at different types of plate margins that lead to earthquakes and volcanic activity
constructive: occurs where two plates (oceanic or continental) move apart
destructive: occurs where an oceanic plate and a continental plate converge (meet)
conservative: occurs where plates move past each other in different directions or at different speeds
describe the primary and secondary effects of a tectonic hazard
primary:
- buildings, structures and homes are destroyed
- communication and transport links are disrupted
- people are left homeless
secondary:
- disease can spread because of contaminated water and poor sanitation
- reconstruction can be costly
describe the immediate and long term responses to a tectonic hazard
immediate:
- evacuate anybody at risk, rescue survivors and treat injuries
- recover any dead bodies
- set up temporary shelters
long-term:
- rehouse those that have lost their homes
- restore water, energy and gas supplies
- boost the economy by promoting investment in the area
state reasons why people continue to live in areas at risk from a tectonic hazard
- people trust that the earthquake resistant buildings are strong enough to protect them
- the soil in volcanic areas is extremely fertile, making it excellent for agriculture
- housing is cheaper in these areas
- geothermal energy plants create lots of job opportunities
explain how monitoring, prediction, planning and protection can reduce the risks from a tectonic hazard
monitoring and prediction: GPS receivers can detect or measure movements in the ground - scientists can monitor the movement of tectonic plates to make predictions and provide vital warnings
protection: earthquake-resistant buildings and infrastructure can be built - when an earthquake occurs, strong furniture such as desks and tables, can be used as overhead protection
planning: evacuation plans should be made to get people out of danger as quickly as possible - people can be educated on what to do in the event of an earthquake
used named examples to show how the effects and responses to a tectonic hazard vary between two areas of contrasting levels of wealth
chile:
- 27th Feb 2010: occurred at a destructive plate and followed by a series of aftershocks
primary effects:
- around 500 people killed and 800 000 people affected
- much of chile lost power, water supplies and communications
secondary effects:
- 1500km of roads damaged, mainly by landslides
- several coastal towns devastated by tsunami waves
immediate responses:
- power and water restored to 90% of homes within 10 days
- emergency services acted swiftly
long-term responses:
- president announced that it could take up to 4 years for Chile to recover fully from the damage
used named examples to show how the effects and responses to a tectonic hazard vary between two areas of contrasting levels of wealth
Nepal:
- 25th April 2015 struck by a magnitude 7.9 earthquake at a destructive plate margin
primary effects:
- 9000 people died and 20 000 people were injured
- electricity, water supplies and communications affected
secondary effects:
- 3 million people left homeless
- reduced tourism: caused a decline in employment and incomes
immediate responses:
- international help was requested
- 500 000 tents were provided
- helicopters rescued people on Mount Everest
long-term responses:
- roads were repaired and landslides were cleared
- stricter law on building codes
