tectonic hazards Flashcards
Natural hazards
when a natural event can threaten people or has the potential to cause damage disaster or death
main types of hazards
- atmospheric (e.g hurricanes) caused by air rapidly heating and cooling
- hydrologic from too much or too little rain
- geological
- biological (e.g forest fires or a pandemic)
factors affecting hazard risk
- climate change
- development of area (infrastructure )
- size of the nearby population
- frequency of the hazard
- preparedness
continental crust vs oceanic crust
continental usually less dense, thicker and made of granite hence causing oceanic plates to be subducted below it
inner core
diametre- 2440Km
solid
Iron and Nickle
Outer core
2300 km thick
liquid
4000-5000 degrees
Mantle
molten material moving around - goes from more liquidy to more solidy
2900Km
500-900 degrees celsius
ridge push explained
lithosphere (lower part of crust) is pushed upward due to convection currents which causes the lithosphere to thicken resulting in the sloping of the asthenosphere (top plasticy layer of the mantle). Gravity forces the denser lithosphere to move downhill pushing other parts of the lithosphere ahead of it and creating new crust at mid ocean ridges
slab pull explained
Older, denser tectonic plates sink into the mantle at subduction zones. As these older sections of plates sink, newer and less dense sections of plate are pulled along behind. Sinking in one place leads to plates moving apart in other places.
where are volcanoes formed
At linear belts along plate margins e.g the pacific ring of fire
subduction- composite volcano
divergent/constructive- shield volcano
example of constructive plate boundary
North american plate and eurasian plate (mid atlantic ridge)
example of a conservativetive plate margin
San andreas fault- pacific & north American plate
example of collision
indo australian & eurasian (himalayas)
example of subduction
Nazca plate and south american plate
Japan short term responses
- 100,000 members of the Japanese self defence
- 500,000 people were evacuated to higher ground
- within weeks roads railways
Intermittent power restored even though main source of power was destroyed
japan long term responses
- earthquake drills on the first of september each year
- 10 year 150 billion USD protection plan installed (2012-2022)
- by 2015 most debris cleared and housing built away from low lying land
- 2013 tsunami warning system launched and sea walls built 12.5 m high additionally embankments made to preserve cities, industries and powerplants
- by 2020 30,000 public housing units constructed in place of the temporary settlements
Japan earthquake facts
when: march 11 2011
size of the earthquake-9.0
depth of focus- 30Km
population density- high
cost of damages- $235 billion
casualties- 18,000 deaths and 500,000 rendered homeless
nepal earthquake facts
when: 25 April 2015
size of quake- 7.9
depth of focus- 15km
cost of damages- 5$ billion
casualties- 9,000 people dead, 20,000 injured and 3 million left homeless
short term responses nepal
- SARID rescued 16 survivors
- 1.4 million people needed food water and shelter urgently so World Vision International gave out 8000 meal kits and shelter for 20,000 families
- helicopter rescued people from the avalanche and delivered supplies to the surrounding villages
- more than half a million field hospitals set up by organisations such as the red cross
- 30,000 people immigrated to shelter with friends and family
long term responses nepal
- 2018 new natural disaster risk reduction policy
- by the end of 2015 most access roads had been restored and trekking routes (big source of income were also restored
- 700,000,000$ put in funding from international development association to make more earthquake resilient housing ( by 2020 212,000 new homes had been constructed
