Hazardous earth theory

• Who came up with the plate tectonic theory and when

  Alfred Wegener - 1915
• What was the large continent called before splitting

  Pangea
• What was Alfred wegeners evidence for continental drift

  Shape of continents was jigsaw like

  same geology between South Africa and America

  fossils were found in both places
• What fossils did Alfred wegener use as evidence

  Glossopteris was a plant that can’t pollen across the sea

  mesosaurus was a fresh water animal
• What did Marie tharp discover

  Mid ocean ridge and the rift valley via echo sounding
• When did Marie Tharp discover the mid ocean ridge

  1940s
• What did Harry Hess discover in 1962

  Molten rock was providing new rock in the rift valley pushing the two plates apart.
• What did Fred vine discover in 1960s

  He discovered bands of alternative magnetic rock that were symmetrical on either side of the ridge.
• what is the convection current theory?

  As hot mantle rises it spreads out along the surface and cools down therefore sinking - creates a circular flow which pushing the overlying lithospheric plates apart or together.
• What is ridge push

  Upwelling magma at the ridge creates new crust causing the plates to move apart.
• What is slab pull

  The weight of the cold oceanic crust subducting into the athenosphere pulls down the rest of the plate with it
• What are the 6 types of plate boundaries

  Divergent

  convergent -oceanic+oceanic / continental+continental/ oceanic+continental

  conservative
• What features are found at divergent plate margins

  Effusive volcanoes

  rift valleys

  pillow lavas

  MOR

  black smokers

  strike slip faults

  earthquakes
• What are pillow lavas

  When magma erupts directly onto the sea bed it is cooled quickly so forms rounded mounds
• What are black smokers

  Super heated jets of water reemerge on the sea floor containing metal sulphides
• Why are mid ocean ridges not continuous

  Broken into segments by transform faults
• What is the example of divergent plate boundary

  Mid Atlantic ridge - northern American plate and European plate
• What is the floor of a rift valley called

  A graben
• What magma is produced at convergent boundaries

  Andesitic or rhyolitic
• What forms at the convergent boundaries

  Ocean trenches

  explosive volcanoes

  fold mountains

  reverse faults

  earthquakes
• How do ocean trenches form

  When one plate is subducting it causes the continental crust to buckle and forms a trench. Can be up to 11,000m deep
• How do fold mountains form

  When rock is pressed together and it crumples to form mountains
• Which plate subducts when two oceanic plates converge

  The denser one or the quicker moving plate
• What are island arcs and where are they found

  When an oceanic plate subducts blobs of magma rise and form islands - o/o boundary
• What is a conservative plate boundary

  Two plates slide past each other
• Why is there no volcanic activity along conservative boundary

  No crust is destroyed or created
• Why are we at more of a risk from tectonic hazards - present day

  More developed buildings and cities

  increased population so higher death toll
• Why are we at less risk from tectonic hazards now

  Better mitigation due to better education and technology

  better communication across the globe
• What is the disaster risk equation

  Degree of risk faced by a community due to its vulnerability
• What factors impact a countries vulnerability

  Location - how close to hazard

  magnitude

  depth of focus

  development of country
• How is Japan well prepared for tectonic activity

  87% of buildings in Tohoku are aseismic
• Why are volcanoes less hazardous

  Can be predicted
• What is the parks model of disaster response

  A graph with 5 stages showing how a country comes back from a disaster
• What are the 5 stages of the parks disaster model

  Stage 1 - pre disaster

  stage 2 - disaster occurs

  stage 3 - search and rescue

  stage 4- relief

  stage 5 - recovering
• What is DRR

  disaster risk reduction
• What is disaster risk reduction

  A systematic approach to reducing the risks of disasters.
• What are three sustainable development goals to improve the lives of people

  Zero hunger - prevents starvation and illness

  clean water - stops cholera spreading

  quality education- people know what to do in a disaster
• What is the cause of earthquakes

  Gradual build up of tectonic strain

  pressure exceeds the strength of fault the rock will fracture

  sudden release of energy in the form of seismic waves
• What is the point of failure in the rocks called

  Focus
• What is a shallow focus

  Less than 70km