Natural hazards term 1! Flashcards
What types of natural hazards are there?
Wildfires Earthquakes land slides Drought Volcanoes Tsunami Tropical storm Floods
What is HICs perspective of natural hazards due to economy status?
- take it more seriously
- educated
- adapt the area
- put government funds towards natural hazard responses and mitigation
What is LICs perspective of natural hazards due to economy status?
- may be used to it more so doesn’t effect them
- can’t put systems into place as can’t afford to
- there jobs may rely on the natural hazard
- aren’t educated
- risk to reward
What is a hazard?
Event that causes threat to human life
What is hazard perception
How people view the risk of a hazard
What is an Earthquake
When 2 plays boundaries slide past each other or make contact cause the ground to move
What is a volcano
When 2 plates push together and the ground rises, creating a mound with lava inside
What is hazard risk?
Hwo powerful or distributive the hazard is
What is geological hazard
An earth movement based hazard
What is a tropical storm
An atmosphere storm forming over oceans
Where are volcanoes and earthquakes mostly based at
Usually at coastal areas of countries but always at plate boundaries , usually in the south more than the north
What is park model
It is a hazard response that gives indications and directions on how a country should respond to a hazard. Its aim is to show the effects of a hazard on quality of life over a sequence of time.
What are 4 stages of park model
Stage1: pre disaster
Stage2:relief (hours/days after), immediate response
Stage3:rehabilitation stage (days/weeks) more complex than relief, building infrastructures to deal with hazard effects
Stage4:reconstruction
(Weeks/years) permanent changes to the area to change quality of life and economy
What is resilience
How able the community is to adapt and recover
What is emergency
The state at which a normal procedures are stopped and extra ordinary measures are taken
Positives of park model
Helps to visualise what to do after an event, gives time slot as to when these responses should be done
Negatives of park model
Doesn’t take in consideration economy, hazard magnitude, responses from indoor or outdoor relief, countries may not follow this
What is hazard response cycle
A cycle of events that should happen after a hazard for responses
Steps to hazard response cycle
Step1:preparation (actions prior to event to get necessary resources or systems put in place
Step2:hazard occurs
Step3:response,(rescue and evacuation, relief and external support)
Step4:recovery(long term recovery, internal and reconstruction)
Step5:prevention/mitigation (ongoing process to lessen the severity of hazard on people/property)
- preparation
- response
- recovery
- mitigation
Positives of hazard response cycle
Gives each step a country needs to take, talks about what to do before an event
Negatives of hazard response cycle
Doesn’t include times or suggest about a countries economy or finances that will be taken into account in responses effectiveness
Destructive plate margin (convergent)
Plates move together and the oceanic sinks under the continental volcanoes, earthquakes, fold mountains, ocean trench)
Constructive plate margin
Divergent
When two plates move away from each other
Volcanoes, mid ocean ridge, rift valleys
Conservative plate boundary
Two plate slide past each other
Earthquakes
Collision/convergent plate boundary
2 continental plates collide and the oceanic plate sinks under the continental plate (subduction)
Oceanic and continental crust
Oceanic is heavier and younger,
Continental is lighter and older
Layers of earth
Crust
Mantle
Outer core
Inner core
Lithosphere and asthenosphere
L:solid top layer of crust in which plates are formed
A:soft plastic like rock in upper mantle
What was wagener theory and how did he discover it
Pargea: land before it broke
-He believed that all plate boundaries and countries were once one. -Jigsaw(countries fitting together), -tectonic(same old fold mountains in Different countries over the world), -geological (S America and W Africa had same ancient rock canyons), fossils (same animals that shouldn’t have been able to survive in different climates)
Convection currents
Radioactive decay happens in earths core, rising limb of convection current causing molten rock to melt, semi molten rock spreads out at angle and carries the plate above, this then cools and sinks. Plates move on direction of molten movement
What is paleomagnetism
New rock forms at an ocean ridge on either side of it. Rising magma causes the oldest rock to move further down the slope and youngest to be at the top
Formation of African Rift Valley
Magma moved up causes ground to rise, fault cracks are created , plates move apart causing valleys to fall into the mantle
--_-
Somalian and Nubian plates caused this
Shield volcanoes
Low and flat volcanoes , less dangerous as can’t build up masses of lava unlike composite volcanoes
Oceanic and continental boundary
Oceanic is thinner and more dense so it sinks (subduction)
Volcanoes and fold mountains
Oceanic and oceanic convergence
Oceanic (heavier and older) is forced under the other oceanic plate (lighter and younger)
Causes earthquakes and ocean trenches
Continental and continental
Two plates collide with eachother, the heavier and denser one sinks (subduction) and causes the plate on top of teh sunken one to buckle, this creates mountains (earthquakes and young fold mountains)
What is a hot spot on a volcano
Area on earth over a mantle plume
Mantle plume: area under the rock out layer of earth where magma is hotter than surrounding ones
How are volcanoes formed
The mantle plume doesn’t move so when two crusts are pushed together or apart the lava rises with the moving earth
VEI
volcanoes explosively index measures intensity of volcano eruptions
Lower down the VEI means they happen more often but smaller
Geological observations of monitoring volcanoes
Slope angle: tilt meter is used to measure the change in slop, when a volcanoes is active/about to erupt it changes shape
How does Seismic activity help monitoring volcanoes
Increase in seismic waves hint at eruption. Measured using seismograph
Gas emissions to monitoring volcanoes
As magma rises to surface and it’s pressure decreases gases escape, they then drop prior to escape as magma hardens and seals on the gas.
Formation of earthquake
Pressure buildings up at the point where 2 plates meet, sudden release (rock failure) the waves cause the ground to shake
P waves
Move through solid and liquid, moves back and froward
S waves
Move up and down only through solid but causes more damage
Surface waves (L)
Sideways motion, most destructive outside the immediate area, first feeling of movement
R waves
Along the surface, rolling motion causing earth to move up and down and is the most shaking felt
Formation of tsunami
The ground beneath the water is moved up and down abruptly, mass of water is displaced and starts moving in different directions
Richer scale
Measure the strength of earthquake (10x more powerful then number before)
Mercalli scale
Measures the damage that is done on humans and infrastructure High numbers mean the earthquake is more dangerous to people
What is tropical storm
Violent rotating storm which occurs at the mid latitudes, 27 degrees/ equator as hottest place on earth
Formation of tropical storm
1: Strong winds upward bringing water up due to the warm air from 27degrees waters
2: the evaporated water cools as it rises and forms storm clouds
3: condensing air releases energy to power storm
4: storm is carried across warm water
5: storm develops and eye
6: several small storms combine to form a giant spinning storm.
Saffir Sampson scale
Measures the damage done by tropical storms 1-5
What is wildfires
Any rural fire which is uncontrolled and spreading .
They need heat source, fuel to burn, oxygen supply and topography (fire moves quicker going upwards)
How to prevent wildfires
Water plants/keep area near home hydrated, don’t start fires near furled areas, reduce green house gas emissions
What is slab pull
geophysical mechanism whereby the cooling and subsequent densifying of a subducting tectonic plate produces a downward force along the rest of the plate.
What is ridge push
With rising magma, tectonic plates are push outwards (divergent), ridge push is when plates are forced down hill
What are volcanic gases and what are it’s effects
•Volcanic gases are composed mainly of water, carbon dioxide, and sulfur dioxide. During violent eruptions, these gases are injected into the stratosphere. There, the sulfur dioxide reacts with water to form microscopic droplets, or aerosols, of sulfuric acid.
•Effects: The effects of volcanic gases on life may be direct, such as asphyxiation, respiratory diseases and skin burns; or indirect, e.g. regional famine caused by the cooling that results from the presence of sulphate aerosols injected into the stratosphere during explosive eruptions.
What is acid rain and what are it’s effects
•how does it occur: the sulfur dioxide gas emitted from the volcano reacts with oxygen and moisture in the atmosphere to produce fog, volcanic smog, and acid rain which can be very corrosive
•dangers: the acid rain can travel for miles causing issues in surrounding areas and can cause health problems
•effects: This can pose serious risks to people and animals. Breathing air with more than 3% CO2 can quickly lead to headaches, dizziness, increased heart rate and difficulty breathing. At mixing ratios exceeding about 15%, carbon dioxide quickly causes unconsciousness and death.
What is ash fallout and what are it’s effects
•Volcanic ash is formed during explosive volcanic eruptions. Explosive eruptions occur when gases dissolved in molten rock (magma) expand and escape violently into the air, and also when water is heated by magma and abruptly flashes into steam. The force of the escaping gas violently shatters solid rocks.
•ash from a volcanic eruption
What is pyroclastic flow and what are it’s effects
•A pyroclastic flow is a dense, fast-moving flow of solidified lava pieces, volcanic ash, and hot gases. Pyroclastic flows can also form when a lava dome or lava flow becomes too steep and collapses.
•Reaching speeds greater than 100 kilometres per hour (60 miles per hour) and temperatures between 200° and 700° Celsius.
•pyroclastic flows are considered the most deadly of all volcano hazards.
•On the margins of pyroclastic flows, death and serious injury to people and animals may result from burns and inhalation of hot ash and gases.
What is mudflow
• is a flow of water that contains large amounts of suspended particles and silt. this causes irreversible sediment entrainment.
• Landslides are caused by disturbances in the natural stability of a slope. They can accompany heavy rains or follow droughts, earthquakes, or volcanic eruptions. Mudslides develop when water rapidly accumulates in the ground and results in a surge of water-saturated rock, earth, and debris.
What is tephra and what are it’s effects
• The term tephra defines all pieces of all fragments of rock ejected into the air by an erupting volcano. Most tephra falls back onto the slopes of the volcano, enlarging it.
• When a volcano explodes, it releases a variety of tephra including ash, cinders, and blocks.
What is nuée ardente and what are it’s effects
• A nuée ardente is a turbulent, fast moving cloud of hot gas and ash erupted from a volcano.
• They can engulf victims within seconds. Escape on foot or by vehicle is nearly impossible. People outside the destroyed area can suffer burn injuries or asphyxia from inhaling hot toxic gasses and ash. This slows down how quick emergency services can get there as the hot gas will harm anyone near it and planes/transport will be affected by it
What are lava flows and what are its effects
• Lava flows are streams of molten rock that pour or ooze from an erupting vent. Lava is erupted during either nonexplosive activity or explosive lava fountains.
•lava flows, however, can bury homes and agricultural land under tens of meters of hardened black rock; landmarks and property lines become obscured by a vast, new hummocky landscape. can cause severe burns and often burn down vegetation and structures.
What’s a lahar
•a lahar is a mixture of hot or cold water and rock fragments which flows down the steep side of a volcano.
•This does not have to be during or immediately after an eruption but may be some time afterwards.
•When they stop flowing lahars are capable of settling like concrete and being very hard to therefore remove following an event.
•This can slow down a recovery effort and in some cases means an area may remain abandoned.
What is magma viscosity
•viscosity is the resistance to flow
•The effect of temperature on viscosity is intuitive. the higher the temperature, the more fluid a substance becomes, thus lowering its viscosity.
What is coriolis effect
Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere.
What is ladder fuels (wild fires)
•firefighting term for live or dead vegetation that allows a fire to climb up from the landscape or forest floor into the tree canopy.
•movement of fire across vegetation
What is El Niño
refers to a warming of the ocean surface, or above-average sea surface temperatures, in the central and eastern tropical Pacific Ocean.
What is plinian eruptions
extremely explosive eruptions, producing ash columns that extend many tens of miles into the stratosphere and that spread out into an umbrella shape.
What are the characteristics of a tropical storm
-27 degrees water
-50-60m depth of water
-8-20 degrees north or south of the equator
-75mph wind
-low wind-sheer
What is mitigation
the action of reducing the severity, seriousness, or painfulness of something.
What is adaption
Things done to reduce the chance of an event happening (dealing with the cause)
