P1: Tectonic Hazards Flashcards
What is a natural hazard
A natural hazard is a natural process or event that poses potential risk of damage to property, and loss of life
Types of natural hazards
Tectonic hazards - Tsunami, Earthquake
Geomrphological hazards - avalanche, flood
Atmospheric hazards -hail,hurricane,blizzard
Biological hazards - Wildfire, malaria, grassfire
What is a hazard risk
A hazard risk is the probability of being affected by a natural event
Factors affecting hazard risk
Proximity - how close you are to the event
Urbanisation - highly populated areas are at high risk
deforestation - clearing forests will increase space for lava to flow
climate change - may cause droughts in a lot more areas and flooding in others.
Farming - when a river floods they release nutrients for crops
Poverty - in poorer areas of the world people would live in areas of high risk
Factors that influence the effect of natural hazards
Human - population density, emergency services, warning time, how people react, land use, community preparedness
Physical - geology/soil, magnitude of event, duration of event, frequency, time of day, ground type.
Layer of the earth - Crust
Oceanic - basalt, solid, 6-10km thick, 200-400 degrees celcius., outer layer of crust
continental - Granite, solid , 50-100km, 500-1000 degrees celcius, inner layer of crust
Layer of the earth - Mantle
Top = rock, Bottom = molten rock, solid and liquid, 2900km thick, 400-4500 degress celcius, flows slowly
Layer of the earth - Outer core
Iron and nickel,liquid, 1250km,<3700 degrees celcius, currents generate earth magnetic field
Layer of the earth - Inner core
Iron and nickel, solid, half the diameter of the earth, <5000 degress celcius/
Lithosphere
The solid crust and solid mantle
Asthenosphere
The solid crust is floating on the molten asthenosphere
Three ways heat energy travels
Conduction
Convection
Radiation
Why do the plates on the earth move
As heat rises from the core it creates convection currents in the liquid outer core and mantle.
These currents are so strong enough to move the tectonic plates- they pull and push at the crust.
Radioactive decay in the core creates the heat that is the engine of the plate techtonics
What is a constructive plate margin
Where two plates move apart and molten magnma rises and then cools down to form solid rock. Lava is usually runny and spreads out before it solidifies. e.g. Mid atlantic ridge.
What is a Destructive plate boundary
When an oceanic and continental plate move towards each and the oceanic plate sinks under the continental plate. The friction between the two causes strong earthquakes and tsunamis. e.g. Andes Mountains in Peru and Chile
What is a conservative plate boundary
When two plates do not collide but move past each other. Earthquake occurs. San Andreas Fault.
What is a collision plate boundary
They cause the material to rise upwards forming mountains. Causes destructive earthquakes, landslides. The Himalayas
What is a volcano
A volcano is an opening or vent in the earths surface through which molten materials erupts and solidifies as lava.
Details about a volcano at a Destructive plate margin
Composite Volcano. Lots of layers of ash and lava build around the main vent to form a strato volcano because they release carbon dioxide. At this location adesthetic magnma is made where continental rocks are melted by the magma. It is lower in temperature than the basaltic magma. e.g Montserrat
Details about a volcano at a constructive plate margin
Shield Volcano. Creates basaltic magma. The emerging lava is quite runny and hotter so the shape of the volcano is low and wide. e.g. Sutney Island, Island.
Details about a volcano at Hot Spot Inter-plate
Shield volcano. Magma plumes are formed at these volcanoes. These shield volcanoes have gentle oozing lava which comes out very slowly. e.g. Mauna Loa Hawai
How are volcanoes formed at a constructive plate margin
The techtonic plate is melted by the upper part of the mantle and hot molten magma rises to form a gap. The slab pull allows the lava to pour out and then form solid rock. The tectonic plates are moved apart by slab pull. As more and more lava piurs out a shield volcano forms and the rising magma pours out forming another layer a bigger volcano.
How are volcanoes formed at destructive plate margins
As the two plates move towards each other, the less dense one falls below. the oceanic plate is denser and gets melted below. The composite volcano is then formed.
How are volcanoes formed at Hot spots
The plate moves apart in every direction and gets thin in the middle. This piece then gets torn by melting. Basaltic lava then erupts and then a shield volcano is formed.
Hazards of volcanic eruptions
eruption cloud, ash fall, lava flow, debris, magma, pyrocrastic flow
How can the effects of volcanoes be managed
Prediction - We could use sulphur dioxide detectors to tell us magma is rising. Volcano will change shape as magma moves up vent
Protection - Concrete lahar channels can be built to divert lahar flows away from builds
Planning - People may be given emegency packs.
What is an earthquake
An earthquake is the result of a sudden release of energy in the earth’s crust which causes seismic waves. The pressure is then released along faults sending out huge pulses of energy.
Nepal Earthquake CS - Causes
There were collision plate margins between Indian plate and Eurasian plate.
Nepal Earthquake CS - Management
Temporary Shelters were built.
Nepal Earthquake CS - Primary effects
8,841 people died, over 16800 injured and 1 million homeless. A reduced supply of water, food, electricity. Historic buildings and temples in Kathmandu, Harar tower a UNESCO world heritage site, 20 hospitals and 50% of schools destroyed. 352 aftershocks
Nepal Earthquakes CS - Secondary effects
The earthquake happened just before the monsoon season when rice is planted, 2/3 of the population depend on rice. Triggered and avalanche - 19 people died.
Nepal Earthquake CS - Immediate responses
Nepal requested a lot of help from other countries. The USDEC raised $126 million to provide to rebuild most severely hit areas.
Temporary shelter was set up.
Nepal Earthquake CS - Long term responses
The nepal government carried out a post disaster and needs assessment, They said 23 areas need full rebuilding as they were very important.
Italy Earthquake CS - Causes
There is an african plate which is crashing into the eurasian plate. Both collision plate margins.
Italy Earthquake CS - Managements
There were very effective communication strategies. THere were many machines + monitoring high earthquakes.
Italy Earthquake CS - Primary effects
308 people died, 1500 people critically injured, 67500 people left injured and occured at 3:36 am.
10000- 15000 buildings collapsed.
Italy Earthquake CS - Secondary effects
The amount of students in l’aquil university decreased. Lack of housing increased prices. All of the business districts were cordoned off due to unsafe buildings. Aftershocks triggered landslide and rockfall.
Italy Earthquake CS - Immediate responses
5000 soldiers, alphine guides, police, firefighters and volunteers were involved in the rescue.
THe rescue teams worked throughout the night and the Italian red cross set up tents for those force to leave homes and they provided emergency items.
Mobile kitchens provided 1000 meals a day.
Italy Earthquake CS - Long term responses
The Italian government, promised to move displaced families into camps into lightweight wooden houses. THe italian government will rebuild villages to look the same as they were before as well as being earthquake proof.
How are tsunamis formed
When the oceanic plate sinks below the continental plate there are earthquakes. These cause the water in the gaps to be repelled outwards. This then causes the waves to be sent towards the land.
How can we mitigate the impacts of seismic hazards
Prediction - Use of seismographs, Animals can act weirdly before an earthquake
Planning - educate children in schools to know what to do, Have an earthquake warning system
Protection - Have strong steel frames on buildings which are flexible and stop cracking.
Living in Hazard Prone areas - Geothermal enrgy
Geothermal energy is a major source of electrical power and stema is heated by hot mama in permeable rock. These then turn turbines at power stations. It is renewable which means it will never run out.
30% of Icelands energy
Living in Hazard Prone areas - Farming
Lava and ash erupting from volcanoes can kill livestock and destroy crops and vegetation. after 1000s of years the weathering of this lava releases minerals and leaves behinds extremely fertile soils, which are rich in nutrients.
Living in Hazard Prone areas - Family, Friends, Feelings.
Many people don’t want to leave because of ancestors living here in the past. Sometimes it is easier when people monitoring the natural hazard have asid that the effects are not that severe.
Living in Hazard Prone areas - Tourism
Many tourists come and visit volcanoes for the spectacular view and the very relaxing hot springs, adventure and for thrill seeking.
More than 100million people come and visit volcanic sites every year. The revenue is beneficial.
Living in Hazard Prone areas - Mining
Valuable minerals are found in these areas and many jobs are created in the mining industry. It is not just dormant or extinct volcanoes that are mined but active volcanoes are well.
