Earthquakes and volcanoes

What are they? Seismic waves Richter scale Continental crust Tsunami Tectonic boundary Convergent/destructive margin Divergent/constructive margin Evacuate Geothermal energy Pyroclastic flow energy waves released when plates move past each other logarithmic scale that measures earthquake magnitude thick, granite plates that “float” on the mantle. They are less dense than oceanic plates. wave created by an underwater earthquake where two tectonic plates meet. where two plates meet, oceanic plate is subducted below continental to form volcanoes/earthquakes where two plates move apart creating a chain of volcanoes e.g. Mid ocean trench move people away from danger energy formed by the heat of the earth material erupted from a volcano inc. ash, lava, gas and rocks

The following slide shows 4 plate boundaries. For each one i The following slide shows 4 plate boundaries. For each one i. Name the boundary. ii. Say what hazards it creates. iii. Give an example of where it happens.

A B C D Constructive / divergent collisional Mountains and earthquakes Himalayas Constructive / divergent volcanoes and (very occ) earthquakes Iceland C D Conservative / tranform earthquakes California, Northridge Destructive, collisional volcanoes and earthquakes Andes, Mount St Helens, Montserrat

Minimising the effects Emergency Drills – emergency services know exactly what to do so they are organised [1] and can get people to safety quickly and efficiently leading to less death [1] Measuring gas emissions from vents – as magma rises gases like sulphur are released [1] if emissions are increase it shows an eruption is imminent and so people can be evacuated to safety [1] Placing concrete blocks on the ground – concrete blocks can be placed in the path of lava [1] this diverts the lava away from key buildings or infrastructure [1] reducing damage and speeding up rebuilding Counterweights in buildings – these reduce shaking of tall buildings [1] this leads to less buildings collapsing [1] which reduces the death toll (from falling building material) and cost of damage [1] Monitoring animal behaviour – animals and birds often leave an area in the hours before a quake [1] if animal behaviour is monitored this can give us an early warning sign [1] and can lead to early evacuation [1] Education – If people are aware of danger and how to react to it they can be prepared [1] this means in an emergency they know where to go and how to find out what is happening [1] reducing panic and confusion which can slow rescue [1]

Causes of Hazards Destructive boundary Caribbean and N and S American Plates. Composite volcano which means its eruptions are sudden and violent Divergent boundary N. American Plate and Eurasian. Shield volcano so gentle eruption. Glacier on top of volcano melted forming floods and cooling lava to form ash. Conservative boundary – Caribbean and North American Plates Epicentre was 25km from capital so the major city and centre of emergency planning was destroyed. No strict rules of construction so buildings weren’t strong Conservative boundary N American and Pacific Plate. 15000 aftershocks which lead to damaged buildings collapsing. Landslides blocked roads

Development Compare the likely effects of an earthquake in an MEDC and an LEDC. Explain the likely differences.

Preparing for hazards Suggest two ways that people can prepare for or predict Earthquakes Volcanoes For each one explain how this would be effective