Tectonic Hazards

What is the crust ?

Its the outer layer. Its divided into tectonic plates that float on the mantle. Its thickness varies and is made up of two types of crust. (Oceanic and continental crust)

What is the inner core ?

About 1400km in diameter, a solid and dense layer composed of iron and nickel with temperatures of about 5500 degrees.

What is the outer core?

about 2100km thick,, a semi molten metal layer with temperatures between 5000-5500 degrees.

What is the mantle ?

About 2900km thick, a semi molten layer which is less dense than the outer core.

What is the oceanic and continental crust ?

Oceanic - thinner and more dense

Continental - thicker and less dense

Why do plates move and where do they meet ?

They move because of convection currents in the mantle and meet at plate margins.

what are destructive plate margins ?

Plates that move towards eachother. Its where oceanic crust meets the continental crust and the denser oceanic crust is subducted and destroyed creating gas rich magma. Volcanoes and ocean trenches also occur here. When two continental plates meet the ground is folded upwards creating fold mountains.

what is constructive plate margins ?

When two plates move away from each other. Magma rises from the mantle to fill the gap and cools creating new crust.

What are conservative plate margins ?

When two plates move sideways past each other or in the same direction but at different speeds. Crust isnt created or destroyed.

How do volcanoes form at destructive plate margins?

In destructive plate margins, the denser oceanic crust moves down into the mantle where it melts. A pool of magma then forms and rises into the cracks in the crust called vents. The magma then erupts forming volcanoes.

How do earthquakes form at alll 3 plate margins ?

Destructive - tension builds when one plate gets stuck as it tries moving past the other

Constructive - tension builds along the cracks when the plates try moving away from each other

Conservative - tension builds when the plates that are grinding past eachother get stuck

How do volcanoes form at constructive plate margins ?

In constructive plate margins, the magma rises up into the gap created by the plates moving apart forming a volcano

Planning

• Future developments can avoid high risk areas

• Governments can plan evacuation routes to get people home quickly and safely

How do earthquakes form at all 3 plate margins ?

Destructive - tension builds when one plate gets stuck as it tries moving past the other

Constructive - tension builds along the cracks when the plates try moving away from each other

Conservative - tension builds when the plates that are grinding past eachother get stuck

Protection

Earthquakes - new buildings can use reinforced concrete that absorb the earthquakes energy. Existing builidings can be strengthened with steel frames so that they dont collapse.

Volcanoes - builidngs can be strengthened so that they are less likely to collapse under the weight of the ash

What are constructive vplate margins?

• When two plates move away from each other. Magma rises from the mantle to fill the gap and cools creating new crust.

Prediction

Earthquakes - cannot be reliably predicted, but scientists can forecast where they might occur by movements of tectonic plates

Volcanoes - can be predicted if scientists monitor volcanoes closely.

Reasons why people choose to live in areas at risk of tectonic hazards

• They may have always lived there - leaving means that that they are leaving jobs and family

• In wealthier countries, effective monitoring and evacuation plans can minimise risks

• The minerals from volcanic ash can make volcanic soil very fertile attracting farmers

• Volcanoes are tourist attractions, so lots of people live nearby to work in tourist industries

Monitoring

Earthquakes - seismometers and lasers monitor the earths movements, and can be used in early warning systems to give a small but vital amount of warning before a large earthquake occurs.

Volcanoes - scientists can monitor the tell tale signs that come before an eruption like escaping gas and changes in the shape of a volcano.

What are conservative plate margins ?

• When two plates move sideways past each other or in the same direction but at different speeds. Crust isnt created or destroyed.

How do volcanoes form at destructive plate margins ?

In destructive plate margins, the denser oceanic crust moves down into the mantle where it melts. A pool of magma then forms and rises into the cracks in the crust called vents. The magma then erupts forming volcanoes.