Sub questions:
What is the difference between a hazard, a disaster and a tectonic event?
- What are the different hazards?
- Why are some events hazardous?
- Event profile of hazards (frequency, magnitude, duration, area)
- What are the causes of tectonic hazards?
- Current theories of plate movements.
- What tectonic activity is associated with different plate margins?
- The spatial distribution of tectonic activity
Why are some events hazardous?
What is the difference between a hazard and a disaster? (AS work - Dreggs Model)
A disaster is a natural hazard that destroys property and kills people. Whereas a hazard is a natural event that occurs and has the capability to become a disaster. A hazard does not affect the people and destroy property whereas a disaster does.
A natural disaster is a hazard that can often lead to the loss of thousands of human lives in the areas in which they occur, and can causes considerable amounts of damage to infrastructure, buildings and property. Whereas Natural hazard is a natural event that occur naturally under, on or above the surface of the earth. A hazard does not directly affect people or property whereas a disaster does.
3. What is the risk equation? Explain what it means
The Risk Equation
The Risk Equation is as shown below:
Risk= Frequency or Magnitude of Hazard x Level of Vulnerability
Capacity of Population to Cope
(AS Geography for Edexcel, Digby et al, 2008)
(http://www.scribd.com/doc/14343088/Global-Hazards-Edexcel-AS-Revision)
What are the different hazards?
Volcanoes and earthquakes have many different hazards associated with them. volcanic hazards are below;
Pyroclastic Flow: is a ground-hugging avalanche of hot ash, pumice, rock fragments, and volcanic gas that rushes down the side of a volcano that can travel at speeds as fast as 100 km/hour or more. The temperatures can reach greater than 500° C, sufficient to burn and carbonize wood.
Lahar: is a rapid flowing mixture of rock debris and water that is created on the slopes of a volcano.
Ash: Volcanic ash is created during explosive eruptions by the shattering of solid rocks and violent separation of magma (molten rock) into tiny pieces.
Volcanic bombs: are lava fragments that were ejected during viscous eruption
Tephra: is a term used for fragments of volcanic rock and lava of any size that are catapulted into the air by explosions or carried vertically by hot gases in eruption columns or lava fountains.
Eruption cloud: is a cloud of tephra and gases that forms downwind of an erupting volcano is called an eruption cloud. The vertical pillar of tephra and gases rising directly above a vent is an eruption column.
(http://volcanoes.usgs.gov/images/pglossary/volcano.php)
Earthquake hazards are below;
Tsunami: A tsunami is a sea wave that results from large-scale seafloor displacements associated with large earthquakes or exploding volcanic islands.
Liquefaction: A process by which water-saturated sediment temporarily loses strength and acts as a fluid. This effect can be caused by earthquake shaking.
Displacement: Displacement is the difference between the initial position of a reference point and any later position.
Ground Shaking: Ground shaking is both a hazard created by earthquakes and the trigger for other hazards such as liquefaction and landslides. Ground shaking describes the vibration of the ground during an earthquake.
(http://www.crew.org/earthquake-information/earthquake-hazards)
Event profile of hazards (frequency, magnitude, duration, area)
Event profiles are a common way of comparing different hazards. They are good for comparing different hazards as many different factors can be incorporated into them and also the scales are not too specific so they are easy to create.
(Chaffey, J. et al (2006) Natural Hazards 2nd Edition)
3th February 2014
Research the different types of plate boundaries and where they are located.
There are three types of Plate Boundaries and these are;
Divergent
Convergent
Transform
The Divergent plate boundary is when the tectonic plates are slowly moving away from each other. As the magma rises this pushed the two tectonic plates apart. Frequent earthquakes occur along the Divergent plate boundary. Earthquakes are in this plate boundary usually have a magnitude of less than 8.0 on the Richter scale (Byrne et.al, 2009)The convergent plate boundary is when the tectonic plates collide together, This in turn causes one or both of the tectonic plates to force up on which forms rugged mountains. Contributing to why Mountains are found on top of tectonic plate boundaries. If one out of the colliding plates is made from oceanic crust, this is subducted into the mantle where it melts forming a magma chamber. When magma builds up it can then be released forming a composite volcano. The friction of the two plates can also cause earthquakes.
The Transform plate boundary is when two plates slide past each other. The plates alternately jerking against each other cause earthquakes to rattle through a wide boundary zone. Crust is cracked and broken at transform margins, but is not created or destroyed.
(Pearsons Education Limited: 'Edexcel Specification GCE Geography' 2013)
Research the distribution of recent tectonic activity
Earthquakes
The Wenchuan Earthquake in China on the 12th May 2008 The impact of the Wenchuan earthquake on the mountains of the Longminshan range was extraordinary. Many buildings were destroyed due to be being poorly built by the Chinese government. The buildings collapsing killed many people.
Tsunamis
The Indian Ocean Tsunami on the 26th December 2004This disaster is the most significant in the last ten years. It was so significant due to the death toll being so high. The main reason the death toll was so high is because the population within this area were not prepared and notified that the tsunami was about to occur.
Volcanic Eruptions
Eyjafjallajökull eruption in 2010
This eruption caused volcanic ash to spread across Europe. No one was killed however lots of livestock died. The ash also caused people to have chest problems and asthma attacks.
HOMEWORK
Mount Sinabung
Type of a plate margin
The Mount Sinabung in Indonesia is located on the Eurasian plate which is located next to the Philippine plate and Australian plate. The Volcano is located in the North of Sumatra. The plate boundary is a convergent boundary hence why the volcano was formed.
Impacts
From the recent eruption the death toll has reached only 16. Fourteen thousand residents were allowed to return to their houses of a 5km danger zone radius after being evacuated, however the next day the Volcano erupted yet again.
Responses
In total 30,000 people have been evacuated. People have had to camp in tents for months. Many people have also been rushed to intensive care units.
Duration, magnitude and frequency of these eruption.
The magnitude of the earthquake that provoked the eruption was 4.8 on the Richter scale. The volcano has been rumbling and erupting for up to four months.
Tungurahua Volcano
Type of a plate margin
The Tungurahua Volcano is located in Central Ecuador. Ecuador is located on the South American plate which is converging with the Nazca plate.
Impacts
Erupted three times, spewing ash and lava in the last three weeks. Pyroclastic flow also stretched to 500metres which has stopped tourists visiting Achupashal. Ash cloud also stretched to 8kilometres so some people suffered from asthmatic attacks. No-one has died or been reported missing yet.
Responses
Achupashal has been evacuated but that is all so far.
Duration, magnitude and frequency of these eruption.
The magnitude of the eruption was 4.5 on the Richter Scale.
Type of a plate margin
The Tungurahua Volcano is located in Central Ecuador. Ecuador is located on the South American plate which is converging with the Nazca plate.
Impacts
Erupted three times, spewing ash and lava in the last three weeks. Pyroclastic flow also stretched to 500metres which has stopped tourists visiting Achupashal. Ash cloud also stretched to 8kilometres so some people suffered from asthmatic attacks. No-one has died or been reported missing yet.
Responses
Achupashal has been evacuated but that is all so far.
Duration, magnitude and frequency of these eruption.
The magnitude of the eruption was 4.5 on the Richter Scale.
4. Select 2 earthquake and 2 volcano case studies with which you can make good comparisons between (for example Haiti and New Zealand). Create annotated risk equations for each.
Haiti 2010 Earthquake
Magnitude 7 on the Richter Scale
Death Toll 230,000 people died Buildings Collapsed 250,000 Residences 30,000 Commercial Depth 13 km
Canterbury Earthquake
Magnitude 7.1 on the Richter Scale Death Toll 0 people died Depth 5 km
5. Create a comparison summary to demonstrate your understanding of the risk equation.
Good, case studies are a little basic. Try to learn the diagrams (for plate boundaries too)
ReplyDelete