Tectonic Landscapes Flashcards
Name and describe each layer of the earth
Inner Core - Centre and hottest part, made of iron and nickel, heats earth
Outer Core - Liquid iron and nickel
Mantle - Widest section, made from semi - molten rock (magma)
Crust - solid outer layer, made from 2 types of plate - continental and oceanic
Explain how the Earth’s plates move
- Heat in magma generated by radioactive decay in core
- Heat rises and falls -> convection currents
- Convection currents move plates
When currents converge - plates move together
When currents diverge - plates move apart
Name and describe the 3 types of plate boundary
Constructive - move apart
Destructive - move together
Transform - slide past
Describe how volcanoes form at a named constructive boundaries
As plates move apart, magma rises
Magma erupts to surfaces, alongside earthquakes
When magma reaches surfaces, cools, solidifies -> new crust of igneous rock
Repeated -> volcano
Large volcanoes at sea -> volcanic islands
Describe how volcanoes form at destructive boundaries
- Oceanic plate is denser than continental plate
- Forced underneath at subduction zone
- Magma collects -> magma chamber
- Rises through cracks in continental crust - as pressure builds -> volcanic eruption
Describe how fold mountains are formed and name the plate boundary they form at
Destructive plate boundary - 2 continental plates
Plates are squashed together and forced up
- creates fold mountains, such as the Alps
Describe how an earthquake happens
- Tension caused by friction between plates
- Pressure released from inside Earth’s crust
- Energy released in seismic waves - spread out from focus, stronger at epicentre
What is the difference between the focus and the epicentre?
Focus = point where pressure released
Epicentre = point on surface above focus
What are the 3 main features of the Richter Scale?
Measures energy released in earthquake
Magnitude increases 10 fold as move up scale
No upper limit to scale
What are the 2 main features of the Mercalli scale?
Measures effects and impacts - damage done and moment felt
Measured in Roman Numerals from I to XII
Give 4 short term and 2 long term social impacts of an earthquake
Short Term:
- Death and injury
- Homes destroyed
- Transport and communication links disrupted
- Water supplies contaminated
Long Term:
- Disease spreads
- Refugees need rehousing
Give 3 short term and 3 long term economic impacts of an earthquake
Short Term:
- Shops and businesses destroyed
- Looting
- Transport and communication links damaged, so hard to trade
Long Term:
- Expensive to rebuild
- Lost income
- Area investment focused on rebuilding
Give 4 short term and 1 long term environmental impacts of an earthquake
Short Term:
- Landscape destroyed
- Fires spread due to gas pipe explosions
- Landslides
- Tsunamis if near coast
Long Term:
- Important landmarks lost
Explain 4 factors affecting the impact of an earthquake
- Distance from epicentre: closer = stronger
- Richter Scale: higher = stronger
- Wealth of country: HICs better prepared
- Time of day: worse at rush hour/ night
Explain 3 reasons why LICS are effected worse by earthquakes
- Few communications: harder for help to arrive
- Worse construction standards: more likely to collapse -> more deaths
- Less money for clean up: can’t rebuild safely and quickly -> more in refugee camps
Give the cause of the 1995 7.4 Richter Earthquake in Kobe, Japan
Movement along Philippines, Pacific and Eurasian plate boundary
Give 4 effects of the 1995 7.4 Richter Earthquake in Kobe, Japan
35,000 injured
Buildings and bridges collapsed
Fires caused by gas explosions destroyed buildings
316,000 left homeless - refugees -> temporary buildings
Give 4 responses of the 1995 7.4 Richter Earthquake in Kobe, Japan
- Evacuation of city, and emergency rations provided
- Rescue teams searched for survivors for 10 days
- Many permanently moved away
- Created jobs in construction industry a when rebuilding
Explain 3 ways of predicting earthquakes
Laser beams - detect plate movement
Seismometer - pick up vibrations: more = possible earthquake
Radon gas escapes from cracks in crust - sudden increase = earthquake
Explain 3 ways of preparing for an earthquake
Training people: earthquake drills, forecasts
Emergency kits: first aid items, blankets and food
Earthquake proof buildings and roads in major cities: absorb earthquake energy, withstand earth movement
Name and describe each part of a volcano
Magma chamber - collection of magma below volcano
Main vent - main outlet for magma escape
Secondary vents - smaller outlets
Crater - created after eruption blows off volcanoes
Explain why a volcanic eruption happens
Pressure in magma chamber forces magma up and out of main vent and secondary vents
Name the 3 levels of volcano activity
Active - frequently erupt
Dormant - temporarily inactive
Extinct - never erupt again
Describe the 4 main features of a shield volcano
- Found at constructive boundaries
- Gentle slopes
- Formed by eruptions of thin, runny lava
- Frequent mild eruptions
Describe the 3 main features of a composite volcano
- Made from altering layers of lava and ash
- Found at destructive boundaries
- Fast pyroclastic flow: made from steam, ash, rock, dust and lava
A supervolcano is a volcano on massive scale
Name a supervolcano and describe 4 main features of a supervolcano
Yellowstone
Erupts 1000km3 + of material
Forms depression called caldera when pressure builds
Ridge of higher land around it
Erupts less frequently - 100,000s years apart
Explain 3 positive effects of a volcanic eruption
- Dramatic scenery attracts tourists - brings income to area
- Lava and ash provides nutrients for soil -> very fertile soil for agriculture
- High heat levels -> geothermal energy
Explain 3 negative effects of a volcanic eruption
- Death and injury
- Landscapes permanently destroyed
- Ash and mud mixes with water -> fast flowing lahars -> destroy settlements
Give 4 effects of the 1980 Mount St.Helens eruption near Seattle
63 dead due to poisonous gases
Lahars covered an extensive area around volcano
Hot ash/gas destroyed forests and logging camps
Ash blocked rivers -> flooding -> communications destroyed
Give 4 responses to the 1980 Mount St.Helens eruption near Seattle
Communications repaired
People rehoused
Volcano now more carefully monitored
Tourism increased - boosts local economy
Describe 3 ways of predicting volcanic eruptions
Seismometer detects small earthquakes caused by rising magma
Thermal imaging techniques detect rising heat around volcano
Chemical sensors measure rising sulfur levels
Describe 3 ways of preparing for volcanic eruptions
Create exclusion zone around volcano
Evacuation plan and emergency basic provisions in place
Funds needed to deal with emergency