Restless Earth Flashcards
What are the Earth’s 4 concentric layers?
Inner core, Outer core, Mantle, Crust
What is the Earth’s crust broken up into?
Tectonic plates
What are convection currents in the Mantle caused by?
Heat rising and falling generated by radioactive decay in the core, which causes the plates to move.
What happens at a Destructive plate boundary?
The two plates collide and one plate flows beneath the other- subduction. Earthquakes and volcanoes occur here.
What happens at a Constructive plate boundary?
Rising convection currents pull the crust apart forming a volcanic ridge.
What happens at a Conservative plate boundary?
Two plates slide past each other. Earthquakes occur here.
What happens during a Collision?
Two continental plates collide and the two plates buckle. Many Earthquakes occur here.
What are the characteristics of a Shield Volcano?
- Found on constructive plate boundaries
- Formed by eruptions of thin, runny lava which flows a long way before it solidifies
- Have gentle sloping sides and a wide base
- Contain basaltic magma which is very hot with low silica and gas content
- Erupt frequently but not violently
What are the characteristics of a Composite Volcano?
- Found on destructive plate boundaries
- Formed by eruptions of viscous, sticky lava and ash that don’t flow far
- Have steep sloping sides and a narrow base
- Made up of layers of thick lava and ash
- Contain andesitic magma which is less hot but contains lots of silica and gas
- Erupts infrequently but violently
What are the 2 scales used to measure the magnitude of an Earthquake?
The Richter scale, The Mercalli scale
What happened in the Kashmir Earthquake in 2005?
- 75,000 dead
- 75,000 injured
- 2.8 million homeless
- Property damaged ($440 million)
- Remote mountainous area
What happened in the California Earthquake in 1989?
- Up to 12,000 homeless
- 3757 injured
- Built up, accessible area
- Property damage ($10bn)
- 63 dead
- Gas mains burst and fires broke out
What are the difficulties in predicting hazards are that we don’t know…
- When it will happen
- Exactly where it will happen
- How big it will be
- What other impacts it may have
- How many people live there
What are the signs of a Volcano nearing eruption?
- Animals and birds moving out from an area
- An increase in gas emissions
- An increase in soil temperature
- The volcano swelling
- An increase in small earthquakes
- Water in ponds getting warmer
How to prepare for an Earthquake?
- Create an exclusion zone around the volcano
- Make sure they have an evacuation plan
- Have an emergency supply of basic provisions
- Ensure that money is available to deal with the emergency
- Ensure that a good communication system is in place
- Build Earthquake proof buildings
- Build roads and bridges which can withstand the power of an Earthquake
