Restless Earth Flashcards
Describe the features of a Destructive plate boundary
Plates move together
Continental and Oceanic crust
Volcano formed, Ocean Trench, Earthquake and Fold Mountain
Describe the features of a Constructive plate boundary
Plates move apart
Oceanic and Oceanic crust
New land is formed, earthquake
Describe the features of a Conservative plate boundary
Plates slide past each other
Continental and Continental crust
Earthquake
Give 2 differences between oceanic and continental crust
Oceanic Newer less than 200 million years Denser and can sink Continental Older more than 1500 million years Less dense and cannot sink
Define Anticline
Upfold of folded rock
Define Syncline
Downward fold of folded rock
Overfold
Rock fold that is folded over to one side
What plates do fold mountains occur at?
Destructive plate boundaries
State two differences between acidic and basic lava
Acidic High silica content Vicious and travels short distances before cooling Composite volcanoes Basic Low silica content Pours easily and travels far before cooling Shield volcano
What is the difference between lava and magma
Magma is underground and lava is on the surface of the earth
Give 3 factors of a composite volcano
- Acidic Lava
- Cone is tall with steep slope
- Irregular with long dormant periods
Give 3 factors of a shield volcano
- Basic Lava
- Cone has gentle slopes and wide base
- Regular frequent eruptions
What is the pacific ring of fire?
A destructive plate boundary around the pacific ocean where half of the volcanoes and earthquakes are
What is the subduction zone?
Where the oceanic plate subducts under the continental plate. This is where an oceanic trench is.
Give four uses of volcanoes
- Farming on fertile soils
- Tourist attractions (hot springs and walking)
- Geothermal energy
- Mining for valuable minerals eg Pumice
Give 3 ways volcanoes can be predicted and monitored
- Seismometers, when magma begins to move there will be hundreds of earthquakes
- Monitoring gases escaping from the volcano like Sulphur dioxide
- Scientists listening to gurgles as the magma moves
Give 3 responses to a volcano erupting
- Pouring seawater on the magma to solidify it
- Evacuation
- Airlifting huge concrete blocks to divert the magma flow
Describe supervolcanoes
Mega colossal
Emit 1000 km3 of lava
Only occur at hotspots, weak areas of crust
Describe the characteristics of Super Volcanoes
They are in large depressions in the ground called Calderas
They have no cone
Rim of the ground is higher than the actual volcano
How is the distribution of Supervolcanoes different to Volcanoes
There are less than 10 Super Volcanoes in the world
3 are in North America
They do not occur at plate boundaries only hotspots
How do earthquakes occur and at what plate boundary
Occur at all plate boundaries
Caused when tension is released from inside to crust
Plates do not run smoothly and sometimes get stuck
This builds up pressure that is released in an earthquake
Define Epicentre
The point on the earth surface directly above the focus
Define Focus
The point in the earth’s crust where the earthquake originates
Define Seismic waves
Shock waves generated by the earthquake at the focus and pass through the earths crust
What are earthquakes measured on?
Seismograph measures magnitude (size)
Give four differences of the Richter and Mercalli scale
Mercalli Uses roman numerals I-XII Measures the impact of earthquake Measured after eq Measured through observation Richter Uses numbers 1-10 Measures the shaking Measured during the eq Goes up logarithmically eg 7 is 10x bigger than 6 Measured on a seismograph
What is a major earthquake?
7.0 on the Richter scale
Give three reasons why a same magnitude earthquake would have a varied impact
- It was at night (no warning)
- People may live near the epicentre
- It may cause a tsunami
What are the 3 P’s of earthquakes?
Predict
Protect
Prepare
Give two example of Predict
- Animals act strangely and crawl out of their homes and dogs howl
- Earthquakes are more likely after long periods without plate movement
Give two examples of Protect
- Buildings must comply with new earthquake standards
2. Cross bracing on buildings and shock absorbers
Give two examples of Prepare
- Organise emergency supplies of food water and power in advance
- Train emergency services like Fire and Ambulance
What is the differences between Prepare and Protect
Prepare is for people, Protect is for buildings
Give three reasons to support the theory of plate tectonics
- The continents fit together like jigsaws
- There is similar soils in different parts that would be together
- There is the same fossil ages in parts that would be joined
Explain convection currents
Circular currents of magma under the earth crusts that explains why plates move towards and away from each other
