Natural Hazards (P1- SEC A) Flashcards
Define hazard risk. (1)
The chance or probability of being effected by a natural event.
What are the factors that increase the hazard risk from natural hazards? (4)
- climate change
- poverty
- urbanisation
- farming
What is a natural hazard? (1)
A threat of a natural occurring event having a negative effect on humans.
A natural disaster happens…
when humans collide with natural hazards
What is the lithosphere? (1)
The crust and the upper-most part of mantle
Define an earthquake. (1)
a sudden, violent period of ground shaking
Define a volcano. (1)
- large, often conical shaped landform that has formed over a longer period of time by a series of eruptions
Define a hotspot. (1)
where the crust is thin and magma is able to break through to the surface
What are the 3 main types of plate boundaries and explain what they mean. (6)
constructive - where plates move apart
destructive - where plate collide
conservative - where plate slide against each other
What are the crust types and what are they made of ?
Continental (under continents) - SI MA
Silica Magnesium
Oceanic (under oceans) - SI AL
Silica Aluminia
What tectonic hazards do destructive plate margins create and how? (4)
EARTHQUAKES - continental crust overlaps oceanic
- friction created/ sudden disengagement of plates
- causes earthquakes
VOLCANOS - continental overlaps oceanic
- oceanic crust sink bc its denser
- as oceanic crust melts (due to friction in subduction zone), becomes magma then rises ( Mid ocean Ridge)
MOUNTAINS - when crusts collide, earth’s crust crumples and forms fold mountains
What happens if a continental plate and a continental plate collide? (2)
- land will fold
- volcanise won’t be able to erupt (magma won’t be able to come out)
- can be earthquakes and mountains formed
What tectonic hazards do constructive plate margins create? (2) Give an example of these hazards.
VOLCANOS- as plates move away from each other, magma rises in-between and cools to form a part of oceanic plate, but it can erupt above or below the surface e.g Japan’s volcanos/pacific ring of fire
EARTHQUAKES - sometimes the plate fractures as it moves causing earthquakes
What tectonic hazard is caused from conservative plate margins? (1) Give an example of these hazards.
EARTHQUAKES - friction created causes earthquakes
e.g. San Andrea’s Fault
California’s earthquakes
What is the ring of fire? (1)
The Ring of Fire is a region around much of the rim of the Pacific Ocean that has a lot of volcanic/seismic activity.
How are earthquakes measured?
The richter scale measures energy released from earthquake from measuring seismic waves.
The mercalli scale measures effect by observation - feel/see
What is a prediction?
Using historical evidence and monitoring.
Scientists make predictions about when and where tectonic hazards may happen.
What is monitoring?
Using scientific equipment to detect warning signs of events.
e.g. changes in water pressure
minor tremors
What is protection? And give examples. (2)
Actions taken before natural hazard to reduce impact.
- buildings with reinforced concrete columns strengthened by steel frames
- use earth embankments/explosives to divert lava flows away from property
What is planning?
Actions taken by communities to respond to /recover from hazard
Identifying and avoiding places most at risk.
e.g. Maps to show location and effects of hazard/ DRILLS
What is the focus of an earthquake?
location within earth where underground rock moves and sends out earthquake waves
What is the epicentre?
location on surface directly above focus .
What are seismic waves?
shock waves created at focus
what is the mercalli scale ?
measures results of earthquakes like shaking and results you can see/feel
what are aftershocks?
as rocks settle in new positions, they create smaller earthquakes
What is subduction and the subduction zone?
When two plates collide and one sinks (the denser one), and becomes a part of the crust.
The zone is where this process happens.
Location, Features, Primary and secondary effects of Chile earthquake. (8)
-coast of central Chile (Nazca plate and South American plate)
- 3 mins/ 8.8 richter scale - 27th feb 2010
- 35km below surface
PE - 500 people killed and 12000 injured
- cost at $30 billion
- much of Chile lost power and water supplies
SE - coastal towns caught in tsunami
- 1500km roads damages due to landslides
Immediate responses and long term responses of Chile earthquake. (4)
PR-emergency services acted quickly (search/rescue)
- power/water restored to 90% homes within 10 days
- raised $60 million after national appeal - build 30,000 emergency shelters
LR- economy could be rebuilt without much international aid
- president announced it would take 4yrs to fully recover
Location, Features, Primary and secondary effects of Nepal earthquake. (8)
North west Kathmandu ( destructive plate between indo- Australian plate and Eurasian)
25 April 2015 - 7.9 Richter scale
15km under surface
PE- 9000 died/2000 injured
- 1.4 mill needed food/water/shelter
- electricity/water supplies affected
- cost of damage $5bill
SE- caused avalanches/ladslides which blocked roads
- avalanches on Mt Everest killed 19 ppl
Immediate responses and long term responses of Nepal earthquake. (4)
IR - search/rescue sent quickly
- international aid was quick
- field hospitals set up to support overcrowded hospitals
LR - roads repaired/ landslides cleared
- people rehoused/damages houses were repaired
- tourism boosted when heritage sites reopened
Explain why earthquakes occur at plate margins.
3 Marks
1) convection currents in mantle move the crust
3) Plates collide
4) plates side against each other causing friction
For monitoring /predicting earthquakes and volcanoes what do scientists use?
Seismometers - EARTHQUAKES
Gas concentrations - VOLCANOES
explain why people may live in areas of high risk ?
Fertile soils: The ash and cooled lava contain many minerals which lead to high yields of crops
Tourism: Many people want to visit areas where there are active volcanoes, this increases the number of jobs available
Minerals and precious stones: These can be mined and sold providing work for local people
Geothermal energy: As the magma is closer to the surface the heat can be used to generate geothermal energy
Creating new land area: Once the lava and ash have cooled, new land areas are formed
