Physical processes and tectonic hazards 1.3

What are earthquakes

Sudden vibrations in Earths crust caused by a release in a build up of energy between tectonic plates

what are Primary waves

fastest, reach surface first, travel through liquids and solids, cause backwards and forwards shaking, least damaging

what are Secondary waves

slower than P waves, only travel through solids, cause sideway motions

what are love waves

slowest, cause side motion, larger and energy is focused on the surface, most damaging

what is a primary hazard

direct result of an earthquake

what is a secondary hazard

result of primary hazard

what are primary hazards of earthquakes

ground shaking- range in duration and severity based on earthquakes magnitude

crustal fracturing (when movement causes earths crust to crack)

what are secondary hazards of earthquakes

landslides - movement of earth triggers collapse of materials down steep slopes

liquefaction- water saturated material looses its strength and acts as a liquid under pressure of shaking.

Damages roads, affects delievry of aid

secondary hazards of volcanoes

lahars- mixture of rocks, mud, water which flows down volcano, Fast flowing and destroys everything in its path

jokulhlaups- heat from eruption melts snow and ice in glaciers causing sudden floods

what leads to a tsunami

when an earthquake occurs beneath the sea bed

what is the main cause of a tsunami

Sea bed jolts, water displaced and forced upwards creating a wave

Wave approaches land, slows down and becomes compressed. Leads to increase in wave height

As wave reaches shore , vacuum created and water recedes rapidly out to sea, leaving sea bed exposed

what are other causes of a tsunami

landslides, due to earthquake and volcanic eruptions displacing the water

underwater volcanic eruptions

What is the focus

Where pressure is released underground and where energy radiates out from

Place with the strongest waves causing the most damage

What is the epicentre

Point directly above centre of earthquake on earths surface

What are seismic waves

waves of energy caused by sudden breaking of rock

What 3 type of waves can earthquakes make

P waves, S waves, L waves

Primary hazards of volcanoes

Asch fall (tephra)- when volcanic rock and Asch is ejected from volcano into atmosphere. Building collapse, air becomes thick causing respiratory problems

Volcanic gases- CO2 and sulphur dioxide released into atmosphere. Travel long distance

Pyroclastic flow- mix of hot rock, lava moving quickly along surface. Destroy everything in its path

Lava flows- molten lava not threat as moves slowly, fast lava dangerous

Case Study- Iceland Eyjafjallajökull volcano

• Erupted in 2010

• Asch clouds from volcano affected flights from Northern Europe for a week

• 100,000 Flights cancelled, airlines lost 1.7 bill revenue

• Flight cancellations impacted Kenya- 20% of economy based on exporting veg to Europe