Tectonic Hazards Flashcards
What is a Natural Hazard?
A naturally occurring event that might have a negative effect on the people or the environment
What are the different types of hazards?
Tectonic
Atmospheric
Biological
Geomorphological - occur on earth’s surface, eg. flooding
What factors affect hazard risk?
Time
Geographical location
Population density
Frequency
Magnitude
Level of development
What is the convection thoery?
Hot magma rises in the mantle away from the core. Cools and sinks back towards the core.
Lateral pressure builds up in the lithosphere causing plates to move with the current
What is the slab pull and ridge push theory?
Ocean ridges are formed at constructive plate margins.
Mantle melts to form molten magma which rises as the plates move apart. It then cools to form new oceanic lithosphere, increases in density over time so it slides down pushing the plates apart.
At destructive plate margins the denser plate sinks back into the mantle under gravity. Pulling the plate along behind it
What type of plate margins are earthquakes found on?
Constructive
Destructive
Conservative
What type of plate margins are volcanos found on
Constructive
Destructive
What is constructive plate margin?
Tectonic plates move apart from each other
Why are earthquakes and volcanoes found at constructive plate margins?
Upper mantle melts and the hot magma rises.
Plates move away from each other, magma rises and then cools down to form rock new oceanic plate.
New solid plate fractures causing MINOR earthquakes.
Shield volcano forms as the melted magma pushes up the crust when it solidifies. Erupts in some places with running lava. FREQUENT LOW INTESITY
Why are earthquakes formed at destructive plate margins?
As the plates converge, pressure builds up and the rock eventually fractures causing earthquakes that can be very destructive.
What is a destructive plate margin?
Move towards each other. Compress and the denser oceanic plate is subducted under the continental plate.
Fold mountains, earthquakes and composite volcanoes occur.
How do composite volcanos occur?
Destructive plate margins when an oceanic plate (denser) is subducted under the continental plate. Fold mountain formed
As the oceanic plate is subducted deeper into the mantle it causes part of the mantle to melt. Hot magma rises up through the lisoshphere and can erupt out the top - through vents - forming a composite volcano
Viscous
Tall/Narrow
Pyroclastic flow
Why are earthquakes formed at conservative plate margins?
Plates move past each other - parallel to each other
Pressure builds up as the slide past each other and frictions causes them to become stuck.
Pressure builds up until the rock fractures causing an earthquake.
Why do people risk living in Hazard areas?
Geothermal energy - doesn’t run out and reduces greenhouse gas emissions
Tourism - People pay to go and visit. Business opportunities.
Farming - Lava deposits minerals leaving extremely rich soils.
Mining - Settlements develop where valuable minerals are found and therefore dormant and extinct volcanoes are mined
Cheap
Family and friends
How can the effects of earthquakes be reduced?
Monitoring/ Prediction - cannot be reliably predicted but movement of plate margins can be analysed. Sensitive Seismologists can detect tremors and foreshocks. Location and time are mapped out so patterns can be established.
Protection - Buildings can be designed to protect the lives of those inside (mitigation) however this is expensive.
Planning - Increases efficient responses and coordinates strategic emergency aid.
- Residents can learn to turn of mains gas and water supply
-Preparing emergency aid supplies
