Natural Hazards (paper 1) Flashcards
what are the four categories of hazards
- atmospheric
- geomorphological
- tectonic
- biological
what are atmospheric hazards
weather and climate related (hurricane, drought)
what are geomorphological hazards
land surface hazards (sinkhole, landslide)
what are tectonic hazards
linked to movements in the earth’s curst (earthquake, volcano)
what are biological hazards
relating to plants and animals (forest fires)
define natural hazard
a natural event that causes loss of life and/or damage to property
what is the difference between a natural event or hazard
an event just happens and there is no loss of life, a hazard kills and damages
what two categories of hazards are geological
tectonic and geomorphological
what two categories of hazards are meterological
atmospheric and biological
define geological hazard
caused by land and tectonic processes
define meteorological hazards
caused by weather and climate
what name is given to a colour key map of the world
choropleth map
are earthquake loactions associated with plate boundaries
yes highly
are volcano locations associated with plate boundaries
yes extremely
are tropical storms associated with plate boundaries
no - they only occur close to the equators
what factors affect hazard risk
- more densely populated areas and countries
- buliding on hazardous lands (flood plains / volcano surroundings)
- relief of the land
- climate change (warmer = more intense storms)
- poverty (forces people to live in hazardous areas)
- topography of land
- magnitude and frequency of an event
- location (on tectonic plate)
define hazard risk
the chance or probability of being affected by a natural hazard
what are the two different types of effects
- primary
- secondary
what are primary effects
an impact or effect of a hazard that occurs as a direct consequence of that hazard (roof tiles falling off / death)
what are secondary effects
hazards that result from an initial event but happen at a later date (diseases / mudslides / ash clouds)
why do people live in hazardous areas
- geothermal energy sources (volanic areas) - iceland & italy
- desired climate
- soil fertility (volcanic areas) - tomatoes in iceland
- resources underground (diamonds) - america
-tourism - blue lagoon Iceland - earthquakes are coastal - helps for fishing
what is the radius (distance from the centre) of earth
6300 km
how many large tectonic plates are there
7
describe the mantle of the earth
- widest & thickest layer
- high viscosity on outside
- low viscosity closer to middle
what are the three plate theories
- convection currents
- ridge push
- slab pull
explain convection currents
- magma near the core is heated up and rises
- magma reaches the crust and cools as spreads sideways
- sinks towards the core dragging the crust above it
- cycle continues
explain the ridge push theory
at constructive boundary
- magma rises
- magma cools to form new oceanic plate material
- forms mountain ridge
- it is very dense and slides down away from the ridge
- this causes tectonic plate to move away from each other
the weight of the ridge pushes the rest of oceanic plate in front of it
explain the slab pull theory
at destructive plate boundary
- denser oceanic plate sinks back into the mantle under gravity
- pulls on the rest of oceanic plate behind it & speeds up
what are the three peices of evidence to continental drift
- study of fossils
- pattern of rocks
- shape of continents fit
what are the two different types of crust
- oceanic
- continental
what are the characteristics of oceanic crust
- younger
- thinner
- heavier (dense)
- temporary = constantly being destoryed and replayed
what are the characteristics of continental curst
- older
- lighter
- pernament = cannot be destroyed
when was Pangaea
250M years ago
explain how the study of fossils is evidence for continental drift
- dinosaus found in Antartica, India & Africa
- land mammel and cannot swim
= no other explaination
explain how the patterns of rocks is evidence for continental drift
- same rocks of same age found in East Canada & West Scotland
- rocks were once very close or joined
explain how the shapes of continents fitting is evidence for continental drift
- south America and Africa
- they were once together
what are the four types of plate boundaries
- conservative
- destructive (convergent)
- constructive (divergent)
- collision
describe a conservative plate boundary
- when two plate boundaries move past each other = strike-slip fault = built up friction released
- San Andreas faults, California
- violent earthquakes
- NO VOLCANOES
describe a destructive plate boundary
- oceanic plate boundary is subducted by continental as it is denser
- Japan
- composite volcanoes (rare violent & steep)
- fold mountains
- earthquakes
describe a constructive plate boundary
- 2 oceanic plates move away from each other = rising magma forms new crust
- mid-Atlantic ridge
- sheild volcanoes (frequent gentle & flat)
- gentle earthquakes (due to less energy)
describe a collision plate boundary
- 2 continental plates collide & cannot sink into mantle
- Himalayas mountain-range
- earthquakes
- fold mountains
what are the two types of volcanoes
- sheild volcanoes
- composite volcanoes
explain and describe sheild volcanoes
- found at constructive plate boundaries
- made up of layers of cooling lava
- fast flowing
- frequent but gentle eruptions
- gas escapes easily
- wide and gentle sloping
- eg Mauna Loa, Hawaii
explain and describe composite volcanoes
- found at desstructive plate boundaries
- made up of layers of ash and lava
- slow flowing, sticky lava
- gas builds up = violent
- steep sides
- melting oceanic plate
- secondary vents
- eg Mount Etna, Italy
describe how volcanoes are distributed globally
- most commonly found overall on plate boundaries
- Pacific Ring of Fire
- mid-Atlantiic ridge
- anamolie = Hawaii ~ hotspot
- anamolie = not all plate boundaries = conservative X!
descirbe how earthquakes are distributed globally
- all plate bounaries
- human activity + risk ~ mining
- Pacific Ring of Fire
- anamolie = Hawaii ~ volcanic hotspot activity
what is actuall meant by the term earthquake
the seismic waves felt during plate movement at plate boundaries
define focus of an earthquake
the exact point in the Earth’s crust where the earthquake started ~ deeper focus = lower magnitude
define the epicenter of an earthquake
the exact point directly above the focus on the Earth’s surface ~ closer to epicenter = higher magnitude felt
why do earthquakes occur
- friction at plate boundaries
- built up pressure released quickly
- huge pulses of energy let out
- Earth’s surface moves violently
what are the 2 scales for measuring an earthquake
- the Richter Scale
- the Mercalli Scale
what is the Ritcher Scale
- scale from 0-10
- a logorithmic scale on energy & movement (increased massively per number)
- measured using seismograph
what are your 2 named examples of an earthquake
- HIC = Chile 2010 ~ 500 dead
- LIC = Nepal 2015 ~ 9000 dead
compare the GDP of Chile and Nepal
- Chile = 38th / 193
- Nepal = 109th / 193
give context to the Chile 2010 earthquake
- 8.8 magnitude
- off coast of central Chile
- desructive plate margine = deep benioff zone
- Tsunami warnings
- 500 dead
- $30Billion
give context to the Nepal 2015 earthquake
- 7.9 magnitude
- epicenter 60km NW from capital Kathmandu
- focus only 8km deep
- collision plate boundary
- $5Billion
- caused avalanches on Everest
give the primary effects of Nepal’s 2015 earthquake
- over 8M affected
- 3M homeless
- 7,000 schools destroyed
- 50% shops destroyed
give the secondary effects of Nepal’s 2015 earthquake
- Avalanches & landsides
- 19 dead on Mt Everest
- River blocked = floods
- tourism declined
- farmers could not harvest rice for over a year
what was worse for Nepal? the primary or secondary effects & why
primary - more deaths and caused social & economic longerm effects - very poor QoL for long time
give the primary effects of Chile’s 2010 earthquake
- over 800,000 affected
- 220,000 homeless
- 4500 schools destroyed
- travel severly impacted
give the secondary effects of Chile’s 2010 earthquake
- tsunami waves devastated several towns
- fire at chamical plant
- landslifde destroyed 1500km of roads
what was worse for Chile? the primary or secondary effects & why
primary - infrastructure destroyed = social impact, schools destroyed = cannot function as usual, caused deaths ~ secondary = no deaths
give the immediate response of Chile’s 2010 earthquake
- emergnecy services responded quickly
- international support = field hospitals, floating bridges
- route 5 temporarily repaired in under a day
- in 10 days 90% homes had power & water
- country raised $60M for emegency shelters
give the long term responses of Chile’s 2010 earthquake
housing reconstruction plan helped 200,000 families