Flashcards
Geography Restless Earth
Cards in this deck (50)
- 1What are the 4 layers of the Earth called?Crust, Mantle, outer core, inner core
- 2What are the broken pieces of crust called?Tectonic plates
- 3What is the name of the edge of the various pieces of crust formed?Plate margins
- 4What are convection currents?Circular currents of heat in the mantle
- 5Why do these plates move?Plates move because of the convection currents within the mantle rising and cooling repeatedly, this cycle puts strain on plate margins which then causes pressure on plate margins causing them to move.
- 6What are the 2 different types of plates called?Oceanic and Continental
- 7Which type of plate is made up of less dense rock?continental
- 8Can continental plates sink?No
- 9What type of plate is older?Oceanic
- 10How thick are Continental plates generally?35km to 75km
- 11Which plate can be renewed and destroyed?Oceanic
- 12How thick is Oceanic plate generally?6km to 10km
- 13What are the four types of plate boundaries?1. Constructive
2. Destructive Subduction
3. Destructive collision
4. Conservative - 14What happens at a destructive collision plate margin?When two continental plates meet they collide, this is because the convection currents in the mantle push the two plates together, the friction caused when the plates collide causes fold mountains to form.
- 15What are the key points to remember about destructive plate margins?Key Points:
no volcanoes are formed
The Himalayas are an example of them
2 continental plates only - 16What happens at a Destructive Subduction plate margin?An Oceanic and Continental plate meet because convection currents push them together, the pressure builds up at the plate margin and the Oceanic plate sinks under the continental plate, the friction this causes makes rocks snap and violent earthquakes occur. The friction also causes heat which melts the plate and the magma from the melted plate rises through the crust, erupts through and makes volcanoes, the gas built up during this process causes violent eruptions.
- 17What are the Key Points to remember about Destructive Subductive plate margins?Key Points:
Only happens when an oceanic and continental plate meets.
Causes violent explosive Volcanoes - 18What happens at Constructive plate margins?Convection currents cause two plates to move apart leaving a gap in the ocean floor. magma (lava) rises filling the gap and then solidifies to form new ocean crust. This new crust pushes the plates up to form a ridge of mountains this only causes gentle volcanic eruptions and gentle earth tremors.
- 19What are the Key Points to remember about Constructive plate margins?Key Points
The volcanoes/ earthquakes are mostly gentle.
There are a lot of volcanic eruptions.
An example is the Mid-Atlantic Ridge - 20What happens at a Conservative plate margin?2 plates meet sliding past each other, and as the 2 pieces grind against each other they get stuck and pressure builds up until the rock crumbles off in violent jolts causing severe earthquakes.
- 21What are the Key points to remember about Conservative plate margins?Key Points:
No volcanoes
California is on this type of margin.
The moving margin is called the San Andreas Fault - 22What did scientists call the Supercontinent?Pangea
- 23Name three major hazards associated with Earthquakes?Death, Landslides, Collapsing buildings
- 24What was the name of the theory proposes by Alfred Wegener?Continental Drift
- 25What unique landforms occur and Destructive Subduction plate margins?Ocean trenches and fold mountains
- 26How are fold mountains formed?1) Sediment is building up in a shallower part of the ocean between two continental/oceanic plates, the convection currents in the mantle push both plates up together.
2) the plate movement is pushing them together causing compression in the oceans plate and the sediment have been packed together and is piling up in the oceans shallow bed.
3) The plate movement has caused the sediment build up to compress and fold up onto each layer causing fold mountains. - 27What are some Key characteristics of Shield Volcanoes?-made of only layers of lava
-Formed at Constructive margins
-lava pours out with little violence
-cone, with wide base and gentle slopes
-regular eruptions
-E.G Mauna Loa in Hawaii - 28What are some key characteristics of Composite volcanoes?-Acid Lava
-Made up of alternate layers of Ash and lava.
-Tall cone, narrow base and steep
-Destructive plate margins
-irregular eruptions
-Montserrat is and example - 29What is an ACTIVE Volcano?A volcano that has had at least one eruption during the past 10,000 years.
- 30What is a Dormant Volcano?A volcano that is not erupting and not supposed to erupt again
- 31What is an EXTINCT volcano?A volcano that has not had an eruption for at least 10,000 years and not expected to erupt again in a comparable time scale of the future.
- 32A Super volcano is...?...A mega volcano that erupts at least 1,000km3 of material
- 33What are the 6 Key differences between a normal volcano and the Super volcano?1) Size- their much bigger
2) erupts a lot more material
3) There are fewer Super volcanoes
4) Shape- caldera
5) less frequent eruptions
6) most explosive volcanoes - 34How are Super volcanoes formed?1. rising magma cannot escape and a large bulge appears on the surface.
2. Cracks appear in the surface and gas and ash erupt from the magma chamber
3. the magma chamber collapses causing a depression called a caldera - 35At what plate boundaries do Earthquakes occur?They occur at constructive, destructive and conservative plate margins.
- 36How do Earthquakes occur at Destructive subductive plate margins?at destructive plate margins, the pressure resulting from the sinking of the subducting plates and the heat melts the plate, the friction and pressure caused can trigger strong earthquakes.
- 37How do Earthquakes occur at Constructive plate margins?Earthquakes at Constructive plate margins are less severe, they are again caused by friction.
- 38How are Earthquakes caused at Conservative plate margins?Conservative plate margins have fierce earthquakes when the plates slide then stick pressure causes stress to build and cause earthquakes.
- 39What is the focus of a Earthquake?the point on the earths crust where the earthquake originates.
- 40What does Epicentres mean?the point on the earths surface directly above the focus.
- 41What instrument is used to measure Earthquakes?A seisomograph
- 42What does the Mercalli scale measure?The effects and strength of an Earthquake
- 43What other scale is used to measure the effects of an earthquake?The Richter Scale
- 44What are the Key Characteristics of the Richter Scale?-Measure Earthquake strength
-Limitless scale
-10 fold increase every time the scale increases by one - 45What are the Key Characteristics of the Mercalli Scale?-Only measures from 1 to 12
-it is subjective to descriptions of damage
-12 is total destruction, 1 is barely felt - 46What are the differences between the two scales?-Mercalli scale is subjective, its based on 'at the time' observations
-The Richter scale measures actual Scientific recordings.
-Mercalli scale ends, Richter scale is limitless. - 47What ways can we reduce Earthquake impacts?-prepare people by practising a drill.
-Have and effective emergency services plan
-Broadcast information.
-Make buildings out of Steel for strength of rubber frames because they absorb shock waves. - 48What causes a Tsunami?A tsunami is a large ocean wave that is caused by sudden motion on the ocean floor. This sudden motion could be an earthquake.
- 49How do Tsunamis form?They form at destructive subduction plate margins.
-Edges of plates bend over under pressure.
-Bending plate releases sudden energy surge.
-Displaces entire column of water above plate.
-Water column splits in two directions
-travels at 800km/h
-Stays low out at sea
-increases in height as it approaches land.
-Can now reach up to 35m in height.
-Slows down when approaches land
-Comes ashore and surges inland.
-can reach up to 3km inland - 50Case studies for this topic will be on a mindmapThey are:
-Alps
-Montserrat
-Yellowstone
-Kobe, Bam
-Indian Ocean Tsunami
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- Flashcards on Geography Restless Earth, created by inayamohmood on 05/04/2015.
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