Geography - tectonic hazards

SUMMER EOY

Name the 2 types of earth crust

Oceanic crust, continental crust

Which plate is in the water

ocenic crust

conetinental crust

Older but less dense and thick

oceanic crust

younger, but denser and thicker

what is convenctional current

flows of heat

what is convenctional current cause by

movement of liquid magma

An example of high tectonic activity

Ring of fire

what happens on a Constructive

the two plates are puller apart magma rises and lava pours out onto the surface.

what tectonic hazards occur at a constructive plate margin

Flatter Volcanoes due to free-flowing lava. And Earthquakes due to the plates shaking and vibrating

what is a sea floor spread

new land is formed on the ocean floor

how does convectional current work

1. when core heats up the magma in the mantle

2. the hot magma is less dense than its surroundings so it rises upwards. When it reaches the top it cools

3. it becomes more dense and therefore sinks back down to the bottom,

4. It is heated up again and the cycle continues

5. The plates which lie on top are pushed and pulled by convection current,

What crust can constructive plate margins occur

continental or ocenic crust

direction of constructive

pulls away

direction of destrative

towards

direction of conventional

alongside each other

Destructive plate margins

1. the denser plate '(usually oceanic) subducts below the less dense plate

2. the plate is then subducted leaving an ocean trench

3. friction between the two plate cause strong deep earthquakes

4. the oceanic crust is melted and it is pulled deeper into the mantel creating magma.

5. this causes pressure to build up under the crust,

6. eventually the magma pushes out creating explosive volcanoes.

what is the litmosphere

the area below the crust

Can destructive plate boundary be between 2 oceanic plates

Yes, e.g the Mariana trench

what happens when 2 continental plates meet at a destructive plate boundary

Neither can subduct therefore the crust is crumpled upwards by the pressure creating fold mountains. e,g, Himalayas

what happens at Conservative Plate Margins

1. parallel plates move in different directions at different speeds.

2. this causes friction

3. over time the friction builds up leading to a sudden jolt

4. this releases alot of energy and sends vibrations through the ground, (earthquake)

5. on an oceanic crust this can cause a tsunami

Can volcanoes form on conservative plate margins

no because there is no magma

primary effect meaning

the effects that are directly cause by the natural hazard

example of primary effect

people being killed or injured when a building falls down or lava and ash damages infastructure

Secondary effects

the effects that result of the primary effects

examples of secondary effect

homelessness due to homes being destroyed, or a tsunami or landslide caused by the original earthquake

immediate responses aim

to reduce loss of life and provide vital aid and resources. e.g search and rescue, medical care, food and water, shelters.

long term response aim

to restore normality and reduce risk in the future. e.g. rebuilding infrastructure and homes, cleaning up the effect of the hazard, building defence mechanisms, setting up warning systems

Why do people choose to live in hazardous areas?

tourism,

infrequency of tectonic hazards

cant afford to move

volcanoes → fertile soil

what is monotoring

detecting and recording physical changes and warning signs

what is predicting

using monitoring as well as historical trends and computer based modelling to predict when a tectonic hazard may occur.

can we monitor earthquakes

no because they don’t display any warning signs.

what are some signs of volcanoes

• bulges in the ground indicating a movement of magma

• changes in tempretuere

• changes in sulforous gas

• vibrations

• small eruption’s of smoke and steam

examples of protection for volcanoes

concrete blocks to redirect lava flow

protection from earthquakes

• fire resistant buildings

• foundation built deep into the ground reducing collapsing (e.g Japan, Chile)

• interlocking steel frame

examples of planning

• evacuation plans

• imp0rtant buildings not being built on fault lines (e.g. hospitals or nuclear power plants)