The Restless Earth Flashcards
When are ocean trenches formed?
At destructive plate boundaries like fold mountains. When an oceanic plate and a continental plate collide, the oceanic plate sinks below the continental plate in a process called subduction as it is denser than the continental plate. As it does so, a deep ocean trench is created.
When are fold mountains formed?
When 2 continental plates meet at a collision boundary. An example of a range of fold mountains is the Alps, formed as the Eurasian Plate and African Plate collide.
Where are composite volcanoes found, what shape are they, how often do they erupt, what are the eruptions like and what’s the lava like?
Found at destructive plate margins, they have steep sides with alternate layers of ash and lava, they rarely erupt, their eruptions are violent, and the lava is sticky and acidic.
Where are shield volcanoes found, what shape are they, how often do they erupt, what are the eruptions like and what’s the lava like?
Formed at constructive plate margins, they have a wide base with generally sloping sides, they erupt frequently but the eruptions are not violent and the lava is runny, so it flows far, and non-acidic.
What are the Himalayas, who are they used by and what are the used for?
A range of fold mountains formed where the Eurasian and Indian plate collide. They are used by tourists, farmers and for hydro-electric power.
What are the benefits/drawbacks of tourism in the Himalayas?
Advantages:
Brings in virtual money, Sherpas earn money to send back to families, rich culture and religious tradition and the government earns from climbers.
Disadvantages:
Rubbish everywhere, steal power for heat/fuel an overcrowding.
What are the benefits/drawbacks of hydro-electric power in the Himalayas?
Advantages:
Heavy rains and melting glaciers provide plenty of water and steep sided valleys make a lake with large capacity.
Disadvantages:
Loss of villages - disappear underwater as lake rises and loss of money trying to invest in large projects.
What are the primary effects of the Haiti earthquake?
Main port damaged
Roads blocked by fallen building and smashed vehicles
Eight hospitals and many government building destroyed
200,000 homes damaged - 1.3 million homeless
What are the secondary effects of the Haiti earthquake?
Much of the country lost power, water supplies and communications
Tsunami caused damage to several other countries
Chemical plants caught a fire - had to be evacuated
Copper mines damaged - crucial to economy
What are the primary effects of the Christchurch, New Zealand earthquake?
Large areas uninhabitable Water mains damaged/leaking 2100 injured; 181 fatalities Half of all CBD building in ruins 80% go without electricity
What are the secondary effects of the Christchurch, New Zealand earthquake?
Businesses closed - no income/job losses
Schools shared premises due to lack of classrooms
Communication under stress - phone lines/roads/rail
Psychological impacts
Christchurch can’t host Rugby World Cup
What were the responses to the Christchurch, NZ earthquake?
$898 million paid out in insurance claims
Temporary housing was provided
Water and sewage was restored to all households by August 2011
80% of roads and 50% of pavements repaired by August 2011
What causes earthquakes?
Tectonic plates sometimes move very suddenly. When this happens, an earthquake occurs as shock waves radiate from the focus deep beneath the earths surface. The point immediately about the focus is the epicentre.
What is the Richter scale?
Measures the intensity of an earthquakes based on it’s magnitude, measured by a seismometer. Each integer represents a tenfold increase. Only gives a rough idea of the impact, impacts varies based on other factors.
What is the Mercalli scale?
Measures extent of damage caused by the Earthquake based on eyewitness information. Rating can be largely subjective.
