Hazards Flashcards
what is a hazard?
A hazard is a perceived event that threatens life and property.
They often result in loss of life/damage to the environment.
example of a natural hazard?
-Volcanic activity
-seismic activity
-tropical storms
ALL-CAUSE (DID) DEATH, INJURY, DISRUPTION
hazards pose danger to people, what have the population done to increase the danger of hazards?
-build shanty towns on unstable tropical slopes
-urbanise volcanic zones
-live in areas with active faults
-areas susceptible to hurricanes and tsunamis
what is fatalism?
a view that people cant influence the outcome, therefore do nothing to MITIGATE (reduce the impact of hazard)
reasons for people living in a high-risk environment?
-hazard events are unpredictable
-lack of alternatives (people cant uproot themselves from one place and move to another, giving up their homes)
-changing the level of risk (overtime the risk increased eg: deforestation = increased risk of flooding in the area and higher risk of landslides)
-cost/benefit: California is susceptible to earthquakes, however, the benefits of opportunity out way the costs.
-perception ( model of vulnerability)
HICs to minimise the impact of natural hazards
-building sea walls
-earthquake-proof building
-better emergency services
-better educated
different INFLUENCES in which a hazard is perceived
-socio-economic status (wealthier feel more prepared, this can be due to technological based solutions)
- level of education
-occupation
-religion, culture
-family and marital status
-past experience
-values, personality and expectations
people may perceive hazards in different ways?
Fatalism- acceptance, in some areas believing it is in gods hands. so actions usually concerning safety and losses are accepted and inevitable.
Adaptation- people prepare by prediction, prevention and protection.
fear- people are so scared they leave the area and move away to regions unaffected by hazards.
what is integrated risk management
often incorporates:
-identification of the hazard, analysis of the risks
-establishing priorities
-treating the risk and implementing a risk reduction plan
-developing a communication strategy
how can people use prediction as a way of managing a hazard
prediction- given warning. key thing is to improve MONITORING in order to give better predictions so warnings can be issued. (NATIONAL CENTRE IN FLORIDA, how prediction can depend on monitoring, through the use of info from satellites)
how does prevention manage a natural hazard
natural hazard this is very unrealistic although ideas of seeding clouds in potential tropical storms to cause more precipitation would weaken the system as it approaches land
how does protection manage a natural hazard
the goal is to protect possessions, by modifying the built environment such as sea walls and earthquake-proof buildings.
Governments can try and change attitudes and behaviour to natural hazards which will reduce vulnerability.
name a case study that had management schemes that were a success
-mt etna= dynamite to divert the lava flow
-iceland (Eyjafjallajökull) pouring of sea water on lava flows
name a case study that had failed management schemes
Japan earthquake (1995) city of KOBE
-Japanese felt well prepared
-destroyed 100,000 buildings and 300,000 damaged
-6,000 death toll
-35,000 injuries
what is Disaster management cycle
PRE-disaster- risk management, mitigation/prevention, preparedness
response to the event- warnings/evacuation, saving people, providing immediate aid, assessing damage
POST-disaster- restoration, reconstruction(BBB), economic & social recovery, risk assessment/prevention
what is the disaster response curve AKA: park model
1st stage RELIEF (hours-several days)
-medical attention, rescue services and care are delivered
2nd stage REHABILITATION (days-weeks)
-try and return to normality by providing food, water and shelter for those most affected
3rd stage RECONSTRUCTION (weeks-years)
- infrastructure and property and crops are grown back
-use the experience of the event to try and learn for the next one
SOME COUNTRIES DONT REACH NORMALITY AGAIN (HAITI)
what is distribution of a hazard
refers the to the spatial coverage of the hazard.
-wider effect (tsunami and volcanic eruptions Iceland)
what is magnitude of a hazard
size and impact
PLATE TECTONIC THEORY: GEOLOGICAL EXPLANATION
-Jigsaw fit
-evidence of a carboniferous glaciation 290 million years ago, with deposits found in INDIA, SOUTH AMERICA, ANTARCTICA
-rock sequence in northern Scotland and eastern Canada
PLATE TECTONIC THEORY: biological evidence
-fossil brachiopods found in Indian limestone are comparable to similar fossils in Australia
-fossil remains of a reptile (Mesosaurus) found in both South America and southern Africa this reptile could go in seawater so couldn’t have crossed the Atlantic
-fossilised remains of a plant which existed when coal was being formed have been located only in INDIA & ANTATRICA
what is Sea-floor spreading
-large tectonic slabs of the lithosphere -split apart from each other
-occurs at a divergent plate boundary
-as plate tectonics slowly move apart —> heat from the mantles convection currents makes the current material rise —> often forming a mountain of an elevated area of seafloor
describe the process of convection currents
- under the earth, the crust transfers heat which rises through the surface and cools back down in a circular motion.
-the convection currents converge –> plates move towards each other —> plates converge and the plates move together AKA RIDGE PULL
what is gravitational sliding
sliding away of plates from a spreading ocean ridge takes place with plate movement driven because of the higher elevation of plates at ocean ridges.
what is ridge push
as fresh magma wells up at the mid-ocean ridges to form the NEW YOUNG, oceanic lithosphere, a higher elevation is formed at spreading ridges.
- new oceanic crust gradually cools and thickens with age and is pushed downhill as new magma emerges from the active zone of divergence
what is slab pull
-more significant gravitational force acting on plates —> the movement is driven by the cold, older, more dense rock —> sinking into the mantle at deep ocean trenches and pulling the rest of the plate slab with them as gravity causes the slide downwards.
DIFFERENCE between slab pull and ridge push
Slab Pull: The force exerted by the weight of the subducted slab on the plate it is attached to.
Ridge Push: The pressure exerted by the excess height of the mid-ocean ridge.
how are rift valleys formed
eg: in EAST AFRICA
- when plates move apart on continental areas
- areas of crust drop between parallel faults to form the valley. an area between 2 parallel rift valleys forms an upstanding block AKA:HORST
what is pyroclastic flow
contains a high-density mix of hot lava blocks, ash, and volcanic gas
more at a very high speed down the volcano
destroys nearly everything in its path
extreme fires ignite and melts snow and ice
what is acid rain and how does volcanoes affect climate change
volcanoes impact climate change by causing amounts of volcanic gas, and aerosol droplets of ash injected into the stratosphere.
gases like sulphur dioxide cause global cooling, and CO2 promotes global warming
acid rain- volcanoes emit gases which include sulphur, which combines with atmospheric moisture to form acid rain
what is volcanic gases
include CO2, carbon monoxide, hydrogen sulphide, and chlorine.
1986 CAMEROON (CRATER OF NYOS) killed 1,700 people due to CO2 emissions
what is a lahars
melted snow of ice as a result of the eruption combined with volcanic ash forms that can move down the course of a river at high speeds
EG: NEVADO DEL RUIZ (that girl)
28,700 population survived
what is a tephra
solid material of varying grain size ranging from volcanic bombs to ash, all ejected into the atmosphere
what are the primary effects of a volcano
tephra
pyroclastic flow
lava flow
volcanic gases
what are the secondary effects of a volcano
lahars
flooding
volcanic landslides
tsunamis
acid rain
climate change
how can you predict a volcano or is it possible?
NEVADO DEL RUIZ - volcanologists couldn’t predict as there was lots of activity within the volcano so couldn’t predict the big eruption.
-studying the previous history of the volcano is important to predict the timing.
-monitoring land swelling
-changes in groundwater levels
-changes in chemical composition in the groundwater and gas emissions.
how can a place protect themselves from a volcano
Mt etna - digging trenches
- dropping blocks into the lava stream
- using explosives to slow down the lava flow and in some cases divert it.
HAEIMAEY (ICELAND) - poured seawater at the front of the lava flow to solidify
HAWAIIAN island - build barriers across the valley to protect settlements
Eyiafjallajokull
-erupted 3 times in 2010 - 20th March/April-may/June
-persistent erupting lasting 39 days
what were the primary effects of Eyiafjallajokull
-ash blocking the sun which meant daytime = night (blackout)
-houses/roads/crops all destroyed
-stopped airspace —> Billions of pounds
—> cost airlines 130 million pounds a day
-Kenya was affected as 5000 workers were laid off from work as flowers and vegetables were rotting in the airport. Kenya’s flower council said they lost 1.3 million each day
what were the secondary effects of Eyiafjallajokull
-sporting events were cancelled due to flights being cancelled (champions league semi-finals feat: Barcelona and Lyon making long journeys by coach)
-fresh food imports stopped
-local freshwater sources CONTAMINATED with fluoride
-flooding —> caused by glaciers
Montserrat background
-300 years dormant
-In 1995 it began to give off warning signs
-largest eruption in 1997
Montserrat effects
1995- devastated the island with pyroclastic flows
—> The island was then evacuated to the north or the island, neighbouring islands, UK
-19 people died due to the eruption (as they wanted to come back to their homes and tend to their crops)
-Lahars (mudflows) destroyed the capital (Plymouth), covered in ash and mud
the airports, hospitals and roads DESTROYED
