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Geography Chapter 2 Key Concepts - Coggle Diagram
Geography Chapter 2 Key Concepts
Chapter 2.1
What results in earthquakes?
Rock masses on either side of the fault are pushed by tectonic forces
Generates friction, causing them to get locked up
one plate eventually slips due to the stress exceeding the strength of the rock
Energy in the form of seismic waves is released
How are earthquakes measured?
Richter scale
Measures the peak magnitude of earthquakes
Movement Magnitude Scale
Measures the AVERAGE magnitude of an entire earthquake
Concepts
Focus
The point where seismic waves are released
Epicentre
The point DIRECTLY ABOVE focus
Chapter 2.2
Volcanoes
What are they?
Landforms created when lava erupts onto Earth's surface and accumulates over time
Types of Magma
High-silica magma
More viscous
Dissolved gases cannot escape easily
Violent, explosive eruptions
Associated with stratovolcanoes
Low-silica magma
Less viscous
Dissolved gases can escape easily
Effusive and gentle eruptions
Associated with shield volcanoes
Types of volcanoes
Stratovolcanoes
High-silica lava will erupt explosively as lava, ash and rocks
Ash and rocks settle on the sides of the volcano and eventually get covered by lava
The lava will travel a shorter distance before solidifying
forms a volcano with steep sides and narrow summit
Mount Mayon, Philippines
Shield Volcanoes
Low-silica lava erupts effusively
Over successive eruption, a volcano consisting of many layers of lava will develop
The lava travels a further distance before cooling and solidifying
forms a volcano with gentle sloping sides with a broad summit
Mount Kilauea in Hawaii
How are volcanic eruptions measured?
Volcanic Explosivity Index (VEI)
The greater the volume of ejected material, the higher the VEI and vice versa
The greater the height of the eruption cloud, the higher the VEI and vice versa
The longer the eruption, the higher the VEI and vice versa
Chapter 2.3
Distribution of earthquakes
Occurs on all types of plate boundaries
Largest concentration of earthquakes is along the Pacific Ring of Fire
Along the Mid-Atlantic Ridge (formed by divergent plate boundary), there is a narrow belt of earthquakes
San Andreas' Fault (caused by transform plate boundaries) has a narrow belt of earthquakes
Earthquakes occur more frequently on convergent plate boundaries
more stress is built up during plate subduction
Broad belt of earthquakes along convergent plate boundaries along Pacific Ring of Fire
Anomaly
: Some earthquakes occur away from plate boundaries, such as within the Eurasian plate
Pacific Ring of Fire
Broad belt of earthquakes and volcanoes along your Pacific Ocean
Comprises of all three plate boundaries
Convergent plate boundaries
Pacific Plate moving towards your Philippine Plate
Divergent plate boundaries
Pacific plate moving away from Cocos plate
Transform Plate Boundaries
Pacific plate sliding past North American plate
San Andreas' Fault
Distribution of Tectonic Hazards
Earthquake Hazards
Ground Shaking
Soil Liquefaction
Loose soil loses its soil structure, transforming into a thick liquid
Landslides
Tsunamis
Volcanic Hazards
Tephra
Rocks ejected from volcano at high speeds
volcanic gases
Lava flows
Pyroclastic flows
Hot cloud of gas, ash and rocks travelling down slopes of a volcano
Lahars
Mudflows comprising water and ash
Landslides
Distribution of Volcanic Hazards
Volcanoes are generally located near convergent and divergent plate boundaries
Magma will rise through weak areas in the earth's crust to the earth's surface
Convergent plate boundaries
A belt of volcanoes along subduction zones in the Pacific Ring of Fire
Divergent plate boundaries
A belt of volcanoes along divergent plate boundaries between North American and Eurasian plate
Hot spot volcanoes
Exceptions that can be found away from plate boundaries
Piton de la Fournaise
Chapter 2.4
Earthquake Hazards
Natural Systems
(Ground Shaking)
Oil and Chemical factories rupture, polluting land and water
(All)
Fractures and uprooting of trees, causing injury of trees and death and damaging wildlife habitats
(Landslides)
debris can bury forest and wetlands
Rivers can be polluted with debris, which can kill aquatic life
Human Systems
(All)
Destruction of property and infrastructure, making it harder for rescue services to supply emergency aid
(All)
Snapping of water pipes, gas and electricity cables
resulting in scarcity of fresh water, disrupting gas supply and also causing a power shortage, making communication between people difficult
People can be seriously injured or killed by getting trapped under collapsed buildings
(Ground Shaking and Soil Liquefaction)
(Landslides)
Debris can hit or bury people , killing them. Debris can also cause floods when they block rivers