tectonic processes and hazards key info Flashcards
where are hazards predominantly found
where earths major plate boundaries meet -
movement of these plates driven by convection currents in the mantle
what happens at a conservative plate B and what does it cause
two plates move past each other in opposite direction or same direction at diff speeds
causes earthquakes
what happens at constructive plate boundaries (divergent) and what do they cause
two plates move apart and magma wells to surface
causes earthquakes and volcanoes
what are destructive plate boundaries (convergent) and what do they cause
oceanic plate subducts under less dense continental place and oceanic melts and forces its way to the surface as magma
earthquakes, volcanoes, tsunami
what happens at a collision plate boundary and what does it cause
2 continental plates move towards each other
fold mountains creating , earthquakes
what does intraplate mean
earthquakes or volcanoes in centre of plate
what theory did Alfred Wagner propose
-idea of continental displacement
- idea that we were once joined in a super continent called pangea
- parts moved due to continental drift
- theory rejected but in 1950s proven using paleo magnetism
who proposed the idea of the continental displacement
Alfred Wegner
what is palaeomagnetism and who found it
2 geologists discovered magnetic stripes parallel to the mid atlantic ridge
stripes corresponded to times earths magnetic field reversed
iron in magma lined itself up
supported theory of sea floor spreading
what is the wilson cycle
the theory that if continents move apart to form ocean basins, other oceans must close
if land moves apart, must also move together
what are earthquakes and what causes them
caused by sudden movements along fault lines proceeded by a build up of strain
when pressure exceeds, rock fractures and sudden release of energy makes ground shake
what are the three types of waves
p waves
s waves
L waves
what are the characteristics of P waves
vibrations caused by compression
spread quickly
arrive first
less destructive
back and forth motion
what are the characteristics of S waves
move slowly
vibrate at right angles to direction of travel
sideways moving and ground goes up and down
what are the characteristics of L waves
surface waves vibration occurring in horizontal plane
side to side
high amplitude
what’s the benioff zone
area of seismicity corresponding with the slab being thrust down in subduction zone
produces numerous earthquakes
deep focused
what is liquefaction
vibrations or water pressure in soil particles lose contact with each other. soil behaves like liquid and can’t hold weight
flows down slopes
what are landslides
movement of rock or debris down a sloped section of land
what causes tsunamis
series of waves caused by earthquakes or volcanoes
along destructive fault lines
release of friction caused subducting plate to lift
displacing water column above
forms waves - up to 30m
what are lava flows
- streams of lava on surface
- very hot and takes years to cool
- not a threat to humans as they move slow
- destroy everything in path eg homes
what is pyroclastic flow
- mixture of hot rock lava and ash and gas
- ejected from volcano
- move extremely fast and destroy anything they touch
- dangerous
- very hot and move around 100km
what are tephra and ash falls
- volcanic rock and ash released into air during eruption
- large heavier peices do not travel as far
- can cause injury and death
- ash falls cover everything and poor visibility
- roofs can collapse due to weight
what are gas eruptions
water vapour, co2 and sulphur
can affect people animals and infrastructure
can travel thousands of miles
what are lahars
- masses of rock mud + water
- move quickly down volcano
- caused when heat melts snow and ice
- vary in size and speed
- can not outrun
- can also be caused by heavy rain
what is jokulhlaup
melts snow and ice
heavy sudden flooding
what are volcanoes and how are they caused
opening in the earths crust through which lava ash and gas erupts
1900 volcanoes are active
how do you measure volcanic eruptions
size and force varies
volcanic explosivity index compares and describes magnitude of erruptions from 0 (non explosive) to 8 (extremely explosive)
the amount and height ejected , duration are measures
how do you predict volcanoes
small earthquakes from magma rising
change in shape
change in tilt
gas- sulphur
temp- magma is close to surface or not
What is a hazard
A perceived natural event that has potential to threaten life and property
what is a disaster
Reality of a hazard happening when it causes significant impact on a vulnerable population
what is the relationship between risk hazards and people due to
unpredictability
Lack of alternatives which is why people stay
Dynamic hazards (made worse by people)
Cost benefit of staying in location
Russian roulette reaction - the acceptance that the risk is going to be something anywhere they live
what is the hazard risk equation and what does it capture
Captures the various components that influence the risk
Manageability
what is the PAR model
Pressure and release model
Works On the basis that a disaster is the intersection of two processes- processes generating vulnerability and natural hazard event
what is a hazard profile and what is it used for
Compares physical processes that all hazards share
Identifies and ranks hazards that should be given most attention
Use to compare the same hazard in different places
Maybe inaccurate
why are hazard profiles used/what are they useful for
implement land use zoning
Hazard resistant designs
Educating locals
Community preparedness
Management strategies
how does governance impact vulnerability
Asset inequality- can’t recover and poor quality housing
Inequality of public services
Political inequality - no recovering
Social status inequality - access to income and services
what are hazard trends
total number has increased
number of deaths from them is falling
economic costs have increased
total number of people affected is rising
reported disasters has risen
what are reasons for changes in hazard trends
improvements in monitoring and tech
global population increased
rapid urbanisation
why is disaster data hard to collect
there is an immediate focus on response not collection of data
methods vary
difficult to gather in remote areas
political biased ( always said to be worse if there are tourists there)
what are physical causes that increase risk of hazards
torrential rain
rapid snowmelt
eruptions
surface runoff
la niña
what are the human causes that increase risk
deforestation
land use change
water management
mining and quarrying
what is hazard management
where gov and other organisations and emergency responders businesses and community groups work together to protect people from hazard
provides help
reduce loss of life and property
rapid recovery
what is mitigation
preventing hazard events
identifying potential hazards and taking steps to
what is preparedness
preparing to deal with hazard
minimising loss of life and property
what is response
responding effectively to hazard
coping with disaster
what is recovery
getting back to normal
short term and long term
what is the parks model and what does it take into account
shows how countries might respond to hazard event
can be used to help plan and understand risk and resilience and prepare for future events
takes into account
hazards are inconsistent
have different impacts
have different responses
country has its own curve
what is the difference between mitigation and adaptatation
mit- avoids or delays or prevents hazard
whereas
adap- reduces the impact
what are the types of adaptation
high tech monitoring
crisis mapping
modelling hazard impact
public education
community preparedness
what is high tech monitoring
allows advances warnings
GIS creates hazard maps
early warning systems by using scientific equip
mobile phone tech for communication
what is crisis mapping
map set up and locals provide info via social media
locations plotted on map and put online
aid directed
used in Haiti
what is modelling hazard impact
computer models lean scientists can predict the impact on communities
compared to effects of different scenarios
what is public education and preparedness
better public awareness reduces vulnerability
regularly practicing emergency procedures
develop plans
what are types of mitigation
land use zoning
diverting lava flows
hazard resistant designs
what is land use zoning
local gov plans to regulate how land in a community should be used
helps protect areas at risk
risk areas used for farming
what is diverting lava flows
path taken by lava is diverted by digging channels
can be hard to predict
what is hazard resistant designs
designing and constructing safe buildings
eg earthquake proof
shatterproof glass
what are the key players in modifying disaster losses
insurers and gov- insurance
money they need to repair
communities- locals are first to respond especially in remote areas
aid donors- emergency aid short term like shelters and long term like rebuilding
NGOs- when local governments is struggling
