Unit 1A - the challenge of natural hazards (2. tectonic hazards) Flashcards
what is an earthquake?
violet period of ground shaking. commonly caused by a sudden movement of rocks within the earth’s crust.
what are tectonic plates
earths crust is split into a number of plates about 100km thick
what are the 2 types of crust
dense thin oceanic crust
less dense thick continental crust
how do tectonic plates move
due to convection currents from deep within the earth.
what happens at a constructive plate margin
plates move apart and magma rises creating a new crust.
what happens at destructive plate margins
plates move towards each other the oceanic denser plate sinks beneath the less dense continental plate. the oceanic plate subducts into the mantle and is destroyed creating a gas rich magma. volcanoes and ocean trenches occur here.
what happens at conservative plate margins
2 plates are moving sideways past each other or moving in the same direction of at different speeds. crust isn’t created or destroyed.
what happens at collisional zones
2 continental plates move toward each other and created fold mountains
what is a volcano
large and often conical shaped landform usually formed over a long period of time by a series of eruptions. Like earthquakes volcanoes occur in long belts that follow the plate margins.
what is the pattern of volcanoes
volcanoes are fed by hot molten rock from deep within the earth. this rises to the surface at constructive and destructive plate margins. volcanoes are also formed at hotspots where the crust is thin and magma is able to break through.
what is the mid Atlantic ridge
An area of volcanoes in the centre of the Atlantic Ocean.
primary effects of earth quakes
death, injuries damage to roads, and damage to buildings
secondary effects of earthquakes
RESULT OF PRIMARY EFFECTS
tsunami, fires, landslides
what is chiles GDP
40th out of 195 countries
what is Nepals GDP
110th out of 195 countries
what is Chiles HDI
41st out of 187
what is Nepals HDI
145th out of 187
what is the date Chiles earthquake occurred on
2010
what was Chiles earthquake on the Richter scale
8.8
what plates were involved in the Chile earthquake
destructive plate margin, Nazca plate moves underneath South American plate
as the plate movement occurred in the Pacific Ocean a lot of sea water was displaced triggering a tsunami
When did the Nepal Earthquake happen
2015
magnitude of the Nepal Earthquake
7.9
what caused the Nepal Earthquake
subduction of the Indo-australian plate beneath the Eurasian plate
what was triggered due to the Nepal Earthquake
huge avalanches and landslides, the earthquake also spread 100km in to Tibet and Pakistan and India
Primary effects of the Chile earthquake
- 500 killed
- 12000 injured
- many homes schools hospitals were damaged and the Santiago airport was also badly damaged
- water electricity and communications were lost.
- 30 billion USD of damage
Secondary effects of the Chile earthquake
fires, landslides and tsunamis broke out
Primary effect of the Nepal earthquake
- 9000 killed
- 20000 injured
- 3 million left homeless
- 7000 schools destroyed
- 50% shops destroyed
- power water communications effected
- 5 billion USD of damage
- 1.4 million urgently need of food and water and shelter
Secondary effects of the Nepal effects
- landslides and avalanches triggered and people trapped under snow and rubble
- blocked rivers people needed to be evacuated
immediate responses of Nepal Earthquake
international aid arrived quickly from china and India
helicopters were used to search for people
half a million tents were provided
immediate responses of Chile Earthquake
emergency services deployed quickly
within 24hrs roads were temporarily repaired
temporary shelters were set up
power and water was repaired within 10 days
60 million USD raised to build shelters
long term responses of Nepal Earthquake
roads repaired and landslides were cleared
thousands of homeless people re housed
7000 schools re built
government enforced stricter building codes
long term responses of Chile Earthquake
month later reconstruction plans to help 200000 house holds
president announced it would take 4 years for Chile to fully recover
how Many people live in seismically active areas
2.7 billion
how many people live near dangerous volcanoes
400 million people
benefits of living near volcanoes
lots of nutrients within volcanic material so this makes the soil fertile, agriculture is therefore a big source of income for people living near volcanoes, volcanic soils are the most fertile in the world
hazardous areas are also good tourism sights
what is one bad reason why people do not move away from hazardous areas
some people may not have a choice and cannot afford to move away
some people may not be made aware that there is a tectonic hazard near by
what are the 4 ways to reduce the effects of tectonic hazards
planning predicting monitoring protecting
what is monitoring
using scientific equipment to detect warning signs of events such as volcanic eruption
what is prediction
using historical evidence and monitoring scientists can make predictions about when and where a tectonic hazard may happen
what is protection
designing building that can withstand tectonic hazards
what is planning
identifying and avoiding places most at risk
name some modern hi-tech equipment to monitor volcanic activity
remote sensing - satellites that detect changes and heat changes to a volcano
seismicity - seismographs record earthquakes
ground deformation - changes of the shape of the volcano are measured by laser beams
geophysical measurements - detects changes in gravity as magma rises to the surface
gas - instruments detect gases released as magma rises
hydrology - measurements of gases dissolved in water
why do people choode to live in iceland despite the many active volcanoes
Over 320000 live in Iceland, there is an effective monitoring system and awareness of potential dangers.
how does iceland benefit from tectonic activity
hot water from within the earths crust provides heat and hot water for nearly 90% of all buildings
thousands of tourists visit mount Eyjafijallajokull
geothermal energy is used for 25% of the country’s electricity
