Tectonics

Question 1

Describe Convection Currents

Answer 1

• Heat from the radioactive core rises pulling liquid rock near the core with it.
• Heat cannot pass through the crust so it is forced sideways.
• Friction between the heat and the crust cause the tectonic plate to move.
• The liquid rock then sinks back down as it cools.

Question 2

Describe Seafloor Spreading

Answer 2

• Occurs at divergent plate boundaries.
• Magma rises and erupts along a mid ocean ridge.
• Older rocks move outwards on both sides of the ridge.
• Magma cools and forms a strip of solid rock in the centre of the ridge.

Question 3

Describe Slab Pull

Answer 3

• Oceanic Crust cools, becoming denser and thicker, causing gravity to force the lithosphere down into the subduction zone.
• As it sinks, it drags or pulls the plate down with it.

Question 4

Primary hazards of Volcanoes

Answer 4

• Pyroclastic Flow - A mix of dense and hot rock, ash and gases.
• Lava Flow
• Ash falls
• Gas Eruptions

Question 5

Secondary Hazards of Volcanoes

Answer 5

• Lahars - A fast flowing mixture of rocks, mud and water which flow down the volcano.
• Jokulhaups - Floods caused by a sudden release of water and rocks when glacial ice is melted by the eruption.

Question 6

Describe Tsunami Formation

Answer 6

• Small earthquake occurs under the sea floor.
• Seismic waves released which cause water column displacement.
• Water column rises
• Waves disperse in all directions
• Waves gain energy as they travel towards the land.
• Waves become taller and slow down due to friction between the shallower seafloor.

Question 7

Haiti Earthquake Fact File

Answer 7

• 12th January 2010
• Epicentre 25km south-west of Port-Au-Prince
• 7.0 magnitude
• 230000 deaths
• 4000 amputees
• 1.5 million homeless
• 70% of buildings destroyed
• Shallow 13km focus
• $18 billion lost
• 6900 cholera deaths.

Question 8

Sichuan Earthquake Fact File

Answer 8

• 12th May 2008
• 7.9 Magnitude
• 90000 deaths
• 3.3 million homeless
• $86 billion lost
• 80% of buildings destroyed
• Lake above city burst its banks which lead to contaminated water and landslides.

Question 9

Monserrat Volcano Fact File

Answer 9

• 25th June 1997
• 40% of island declared uninhabitable
• 5000 people lived in temporary shelters for up to 2 years.
• Unemployment rate rose to 50%
• Funding for redevelopment cost $75 million
• 1/10 chance of death from pyroclastic flows.

Question 10

Iceland Volcano Fact File

Answer 10

• 20th March 2010
• 2 million stranded in airports
• Airlines lost $1.2 billion
• Kenya markets lost $1.3 million

Question 11

Indiana Ocean Tsunami Fact File

Answer 11

• 26th December 2004
• 14 countries affected
• Epicentre north-west of Indonesia
• 9.1 magnitude
• 500000 seriously injured
• $6 million in damages

Question 12

Japan Tsunami Fact File

Answer 12

• 11th March 2011
• 9.1 magnitude
• 18500 deaths
• $100 billion in reconstruction costs
• Fukishima power plant melted down
• Liquefaction occured
• Sea walls sunk by 10m due to earthquake

Question 13

What are the different parts of a hazard profile?

Answer 13

• Magnitude
• Speed of Onset (How slowly or rapidly the tectonic hazard develops)
• Duration
• Areal Extent
• Spatial Predictability
• Frequency

Question 14

What are the different parts of a Disaster Management Cycle?

Answer 14

• Preparation
• Response
• Recovery
• Mitigation

Question 15

Risk Equation

Answer 15

Capacity to Cope

Question 16

What are 3 ways to manage the impact of tectonic hazards?

Answer 16

• Modify the event
• Modify the vulnerability
• Modify the loss