hazardous environments Flashcards
define natural hazard
an event that threatens and causes damage to people, their properties and settlements
4 types of hazards
- biological (living organisms)
- geological (on earth surface)
- climatic (atmospheric)
- technological (caused by humans)
why are hazard risks increasing?
result of human influences: population growth, overconsumption of resources, pollution, urbanisation
4 types of plate boundaries
- constructive
- destructive collision
- destructive subduction
- conservative
what are destructive (subduction) plate boundaries
when oceanic plate subducts under continental plate
friction between movements can cause strong earthquakes and volcanoes
what are collision plate boundaries
two plates of similar densities collide
material buckle and form fold mountains
what are conservative plate boundaries
when two plates slide past each other
earthquakes do occur from friction buildup of stress
what are constructive plate boundaries
when two plates move apart, magma rises up to fill the gap
causes gentle volcanoes, earthquakes
when two oceanic plates move apart = ocean ridges
when two continental = rift valleys
what are hotspots?
anomalies of hot magma rising = mantle plume that doesn’t move
plume melts through crust and escape to surface creating a volcano
create new islands
3 steps to managing tectonic hazards
1 prediction
2 preparation and protection
3 responding and planning after event
how to predict tectonic hazards
- seismometers
- unusual animal behaviours
- seismic gap theory
how to prepare and protect against a tectonic hazard (+3 earthquake-proof buildings designs!)
- improve public awareness eg drills
- earthquake kits
- warning systems
- shock absorbers / base isolators
- counterweights
- deep foundations
responses after tectonic event
- emergency services
- shelters
- hospitals
- stockpiles
- risk assessments
earthquake casestudy nz
Christchurch 2011
185 deaths
developed country
earthquake casestudy haiti
developing country
2010
200,000 deaths
30% increase of population living below poverty line
support from international organisations eg UNICEF and Oxfam
short term (immediate) impacts of earthquakes
- death and injury
- potential transportation + communication damage
- ## destruction of houses, shops, businesses
long term impacts of earthquakes
- diseases may spread
- rehousing, potential homelessness
- high cost of reconstruction
- unemployment and loss of income source
- loss of important landmarks
how are volcanoes formed?
magma rises through crusts of the earth
pressure is built and when release, eruptions occur
after several eruptions, volcanoes are formed from build up of rocks`
3 positive impacts of volcanic eruptions
- scenery created, attracting tourism and income
- minerals deposited in soil, very beneficial for agriculture
- geothermal energy
eg iceland
negative impacts of volcanic eruptions
- lives lost
- land and settlements lost from lahars and lava flows
2 types of volcanoes
- shield - runny, less violent, just consists of lava
- composite - acidic, vicious, violent. cone shaped
conditions for tropical storms to form
- sea water temperature above 27°C
- wind speed of at least 75 mph
- low air presssure
- heat and moisture
- sufficient spin of CORIOLIS effect
how do tropical storms form
Converging winds near the ocean surface forcing air to rise and form storm clouds.
storm clouds to rise to high levels
Sufficient distance from the equator for a spin such as the Coriolis force to take effect.
structure of earth
inner core - soild, hottest part of earth 6000 C
outer core - liquid
mantle - molten
crust - solid, oceanic and continental
where do earthquakes mostly occur
pacific ring of fire
3 scales to measure earthquakes
- Richter - size of seismic waves
- Mercalli - impact (uses photos), easy and universal
- moment magnitude - energy released
scale to measure volcanic eruptions
VEI scale
1-8 to measure intensity
why do tectonic plates move?
due to convection currents in the mantle
that rises to crust, then condenses back to mantle and repeat
Drags the crust along, causing vibration and energy released
how to predict volcanic eruptions?
- rise of ground temperatures
- tremours increase
compare how HICs and LICs prepare and predict for tectonic hazards
HICs possess advanced technologies such as satellites and tiltmeters in Japan, so they have early warning systems with developed transportation and communication services; while LICs lack
HICs have organisations, emergency services and education drills to prepare for such hazards, while LICs cannot afford to do so
nz/japan vs haiti
effects of tropical storms in HICs vs LICs
LICs require international aids to recover, but less economical damage as eg Typhoon Haiyan in Phillippines attacked areas with less investments and development
more damage is caused to HICs from their developments. HICs have well developed insurance systems, can recovery rapidly eg Katrina in New Orleans
scale to measure tropical storms
saffir simpson scale
5 categories, 5 at highest damage
by windspeed, air pressure, storm surges and damage caused
reasons to live in high risk areas
- lack of education and information
-unable to move away eg lack of money - home, have relatives and friends, employment
- attractive benefits (by volcanoes)
give an example of a geological hazard
earthquake
volcano
landslides
give an example of a climatic hazard
tropical storms
floods
droughts
give an example of a biological hazard
diseases
fires
pests
give an example of technological hazards
nuclear explosion
pollution
transport accidents
why are some places more hazardous than others?
- some places experience more than one type of natural hazard events
- some places experience them stronger and more destructive
- some places cope with damaging impacts better
when DESCRIBING a trend/graph… (exam technique that needs to stick in my head)
TEA
Trend
Example
Anomalie
no need “because”
describe the earth’s structure
inner core - solid, hottest part
outer core - liquid
mantle - molten layer
crust - oceanic or continental
why are tropical cyclones damaging?
- torrential rain > flooding
- very strong winds > destructive
- storm surges: rise of sea level, low pressure, damage to coastal areas
different types of crust
-continental: not destroyed so its older
- does not sink
- less dense and lighter
oceanic
- continually renewed, so younger
- denser & heavier
explain the plate tectonic theory
plates move due to convection currents in the mantle - Heat from the core makes magma in the mantle rise towards the crust. As the hot current nears the crust, it begins to cool and sink back towards the core.
describe and explain the formation of hotspot volcanoes
hotspots are locations beneath the earth’s crust where hot and strong rising magma occur.
the crust above a plume is weak, volcanic activity occurs
what landforms are created from constructive plate boundaries?
rift valleys and ocean ridges
hazards from volcanoes
- lava flows: destroy farmland, buildings, transport
- ash: carried in wind,
- pyroclastic flows: lethal gas emissions
what is a volcano?
a mountinous vent in earth’s crust which emits lava and other gaseous products
what is a volcanic eruption?
when molten rock and ash erupts from the inside of the earth
what is a primary hazard?
immediate impact - directly caused by the eruption
what is a secondary hazard?
indirect consequences, result of primary hazards
composite vs shield volcanoes
composite
- found between destructive plate boundaries
- cone, steep sided
- vicious lava, violent eruptions
shield
- formed over hot spots
- basic runny lava
- less violent
where are earthquake hazards strongest at?
close to epicentre
factors that determine the level of damage caused by earthquakes
depth of focus
type of rock
less deep , soft rocks = more destructive
hazards of earthquakes
- shaking, collapse of poor building design
- causing fire
- tsunamis (earthquake with epicentres under ocean generate strong tidal waves)
disadvantages of the mercalli scale
it is based on subjective human experiences and damages done
how are tropical storms surging into inland areas?
wind picks up water and push towards shore
sea “expands”, rise of sea level pushes water fast inland
how are tropical storms formed?
warm air from several thunderstorms mix with warm ocean rise
coriolis effect cause spin, air rises and pressure decreases
gains energy from more warm area, increases strength
where is it calm in a tropical storm?
the eye
where are most affected by the tropical storms?
eye wall
high winds and heavy rain
how do hotspots lead to tectonic hazards?
they are plumes of hot magma
that rises from the earth’s mantle , through earth’s crusts and forms volcanoes
factor that influences the direction of the wind
the coriolis effect
wind moves in the direction of the prevailing wind
how can tsunamis be formed by earthquakes
Earthquakes under the sea bed form shock waves (1) this forms
a wave which splits (1). The wave then gets bigger (amplifying)
and hits the shore (1)
