Tectonics Content Along With Spec And Case Studies Flashcards
Explain the distribution around the world of Earthquakes, volcanic eruptions and tsunamis
- Most Earthquake zones are found at tectonic plate boundaries
- volcanic eruptions occur at or close to plate boundaries except hotspots
- tsunamis associated with activity at a plate boundary
Two facts about the distribution of volcanic eruptions or tsunamis
- 70% of earthquakes fall around ‘ring of fire’ due to the plate boundary
- 90% of tsunami events happen within the pacific basin
What volcano hotspot example will you use? And facts
Hawaii
Hawaii has 15 volcanos
What example do you have of a divergent plate boundary (oceanic to oceanic)
Mid Atlantic ridge at iceland
Example of a divergent plate boundary (continent to continent)
African rift valley
What is an example of a convergent plate boundary (oceanic to oceanic)
Alaska
What is an example of a convergent plate boundary (continent to continent)
The Himalayas
What is the cause of a Tsunami?
Tsunami are generated when a sub-marine earthquake displaced the sea bed vertically as a result of movement along a fault line at a subduction zone
What is an example of convergent (oceanic to continent)
The Andrean mountains
What is an example of a conservative (oceanic to continent)
San Andreas fault
How are hotspot Volcanoes made?
Isolated plumes of converting heat, called mantle plumes, rise towards the surface, generating basaltic volcanoes that tend to erupt continuously
What is a mantle plume
Mantle plumes are concentrated areas of heat convection. At plate boundaries they are sheet-like, whereas at hot spots they are column like.
What is subduction?
The process of one plate sinking beneath another at a convergent plate boundary.
What is gravitational sliding
Constructive margins have elevated altitudes because of the rising heat between them, which creates a slope down which oceanic plates slide
What is slap pull?
Cold, dense oceanic plate is subducted beneath less dense continental plate; the density of the oceanic plate pulls itself into the mantle
What are transform zones?
Conservative plate boundaries consist of transform faults. These faults ‘join up’ sections of constructive plate boundary as they traverse the Earths surface in Zig-Zig pattern
What physical processes have an effect on the magnitude?
Destructive margins have larger magnitudes of up to 9.0.
What are the 3 types of Earthquake waves? Spec 1.3A
Primary
Secondary
Love
What are the characteristics of a P-wave? Spec 1.3A
-The fastest wave so they arrive first
-cause the least damage
-they are vibrations caused by compression
What are the characteristics of S-waves? Spec 1.3A
-Arrive next after primary waves
-shake ground violently, causing damage
What are the characteristics of Love waves? Spec 1.3A
-They arrive last
-they have a large amplitude and cause significant damage, including fracturing the ground surface
How do waves frequency and amplitude affect an Earthquake? Spec 1.3A
The overall severity of an earthquake is linked to the amplitude and frequency of these wave types
What is Crustal fracturing? Spec 1.3A
Earthquakes cause crustal fracturing within the earth but also buckle and fracture the ground surface
What are some physical examples of secondary hazards after an earthquake ? Spec 1.3A
-Landslides
-liquefaction
What is an example you would use in your exam about landslides after an earthquake? Spec 1.3A
30% of deaths in Sichuan, China 2008 were caused due to landslides
What main damages does Liquefaction cause and give an example? spec 1.3A
Lots of damage to roads and bridges aswell as telecommunications because of the surface material losing strength.
60 degrees of tilt was recorded in Japan 2011
What are the 4 primary hazards caused by volcanoes? Spec 1.3B
-lava flow
-Pyroclastic flows
-ash fall
-gas eruption
What are the 2 secondary hazards caused by volcanos? Spec 1.3B
-Lahars
-Jökulhlaups
What is a lava flow? Spec 1.3B
Extensive areas of solidified lava, which can extend several kilometres from volcanic vents.
Where do lava flows occur at? Spec 1.3B
-Subduction zone volcano (composite)
-Hot-spot volcano (shield type)
What is a Pyroclastic flow? Spec 1.3B
Very large, dense clouds of hot ash and gas at temperatures of up to 600C
Where do pyroclastic flows occur at? Spec 1.3B
Subduction zone volcano (composite)
What is ash fall? Spec 1.3B
Ash particles, and larger tephra particles, can blanket large areas in ash, killing vegetation, collapsing buildings and poisoning water sources
Where does Ash fall occur at? Spec 1.3B
-Constructive plate margin volcanos (cinder cone, fissure eruption)
-Hotspot volcano
What is a Lahar? Spec 1.3B
Volcanic mudflows, which occur when rainfall mobilises volcanic ash. They travel at high speed down river systems and cause major destruction
What is a Jökulhlaup? 1.3B
Devastating floods caused when volcanoes erupt beneath glaciers and ice caps, creating huge volumes of meltwater.
How are tsunamis created? Spec 1.3C
They can be generated by large landslides, volcanic eruptions, but most are generated by sub-marine earthquakes at subduction zones.
How do sub marine earthquakes create Tsunamis? Spec 1.3C
The earthquake displaces the sea bed vertically as a result of movement along a fault line at a subduction zone. The violent motion displaces a large volume of water in the water column which then moves outwards from the point of displacement
