1. Characteristics of Hazards

Describe and explain the characteristics and spatial distribution

of your chosen hazards.

EARTHQUAKES

Visit the USGS website.

• Open up the ‘Real-time Earthquake Map’.

• Have a play with the different variable controls.

• Make a note of WHERE earthquakes are occurring around the world.

• Can you describe any distinct patterns?

• Begin to plot areas of earthquake activity onto your world map.

Describe the global spatial distribution of earthquakes:

•

•

•

Recap: There are 4 plate margins…

CONSTRUCTIVE DESTRUCTIVE

CONSERVATIVE COLLISION

Add these annotations to your plate margin diagrams.

Homework

• Print out the PDF document I have emailed you.

• Draw on each of the tectonic plates. This is harder than it looks, but Year 8 managed!

• Label each of the plates, and indicate what type of plate margin each is.

• Add some colour and stick together.

So, WHY do the plates move?

HEAT SOURCE- Radioactive decay in the core

The heated rock expands,

becomes less dense, and rises

to the surface

The semi-molten ro

ck

spreads out at the

surface, carry

ing the

above plates with it

The rock cools as it is far

from the heat source,

becomes more dense, and

sinks back towards the core

The continual heating and cooling creates pockets of movement called convection cells

“Convection cell”

Explain why Earthquakes occur, using the following terms:

• Plate boundary, friction, pressure, energy, seismic shock wave, focus, epicentre.

Shock Waves

• These are energy waves created by the pressure release when two plates slip past eachother.

• These travel below the surface of the Earth.

These are fast moving and can travel through solids and liquids.

These are slower and can travel through solids only.

Surface Waves

• Energy released by Earthquakes can be transferred as movement along the Earth’s surface.

• The two wave types are Love waves and Rayleigh waves.

These are fast moving and do not tend to affect bodies of water. These can be very destructive on solid ground.

These are slower moving, and their motion can disrupt bodies of water, creating large waves and currents.

Measuring Earthquakes

• Richter Scale:This measures the

energy released by an earthquake.

It is a logarithmic scale, which means that a Scale 6 ‘quake is 10 times more powerful than a Scale 5 ‘quake.

Measuring Earthquakes

• Mercalli Scale

This measures the damage experienced as a result of an earthquake, and is calculated by visual evidence.

http://elearning.niu.edu/simulations/images/S_portfolio/Mercalli/Mercalli_Scale.swf

Analyse these two techniques

Richter Mercalli

Strengths

Weaknesses

Where would these rank on the Mercalli scale?