Exam Notes - Tectonic Plates Flashcards
Igneous rock
Formed through cooling/solidification of magma or lava
Metamorphic rock
The resulting transformation of a pre-existing rock. Original rock is subjected to very high heat/pressure, which causes obvious physical or chemical changes
Sedimentary rock
Formed by the deposition of material at the earths surface
Types of plate boundaries
- Converging
- Diverging
- Transformation
Landforms associated with plate boundaries
Fold fault rift valleys ocean ridges deep sea trenches, island arcs
Converging plate boundary (subduction zone)
- oceanic plate subduct underneath continental plate
- oceanic edge is destroyed
- continental crust leading edge is crumpled into fold mountains
Diverging plate boundary
- creates either a deep sea trench or rift valley
- crust cracks, exposing magma from the crust
- creates new ocean floor or mid-ocean ridges
Converging plate boundary (collision zone)
- 2 plates that are the same density converge
- neither subducts, instead the leading boundary crumples to form fold mountains
- volcanoes can also be formed
Transform fault boundary
- 2 plates are moving in opposite directions, parallel to each other
- can occur between any types of plates
- doesn’t create landforms
- causes earthquakes
Types of Volcanoes
Fissure Shield Dome Ash-cinder Composite Caldera
Fissure
low profile
created at divergent plate boundaries
basaltic
gentle eruption
Caldera
Medium profile
skeleton of pre-existing volcano
rhyolitic
violent
Shield
Low profile/dome shape
Composed of individual particles from past eruptions
Andesitic
Intermediate
Cinder/ash
High profile
Crustal rock, lava flows too thin and far to cool, creating a low dome shape
andesitic
Intermediate
Dome/Acid
High profile
Thick lava cools quickly and builds up volcano
andesitic/rhyolitic
Intermediate eruptions
Composite volcano
High profile/classic volcano
Composed of alternate layers of magma and ash
rhyolitic lava
violent
Types of lava
rhyolitic
andesitic
basaltic
Rhyolitic
High silica content
very viscous
Andesitic
Medium viscosity and silica content
Basaltic
Highly fluid
Magma vs Lava
Magma is below ground, lava is above
Focus
Where the earthquake occurs on the tectonic plates
Epicenter
The spot on the earth directly above where the earthquake is occuring
Richter Scale
Measurement of how big the magnitude of an earthquake is
P Waves
The first waves to arrive after an earthquake
“Pressure” waves
highest velocity
S waves
secondary waves
move perpendicular to surface
Primary Hazards
Ash clouds Directed blast lava flows Nuee Ardente Pyroclastic flows
Ash Clouds
Rain down on surrounding areas, can bury areas many meters thick
Lava flows
Commonly accompany volcanic eruptions
Can cause secondaru
usually accompanied by poisonous gases
Directed blast
Explosion of vent, throws debris in the air
Nuee Ardente
Ash and gas charged cloud that travels rapidly down the slope of volcano
Pyroclastic Flows
Dense avalanche of hot gas, ash and blocks that cascade down slopes during eruption
Can also form in less energetic eruptions when material “boils” over
Secondary Hazards of Volcanoes
Lahars (mudflow) Tsunamis Fire Mass wasting Disease
Lahars
Debris flow
Slurries of water and rock particles that behave like wet concrete associated with volcanic eruptions
Extremely destructive but topographically controlled
Tsunamis
Volcano is near the ocean, side blows off (possibly from direct blast) huge amount of debris falls into ocean creating a tsunami
Mass Wasting
Icy ground cover of volcano melts and mixes with soil to form mud as the magma in the volcano stirs preceding eruption
Disease
Health centres destroyed
Cut off from getting supplies
Lack of health care
