From Wegener to Plate Tectonics
Who was Alfred Wegener?
German geologist and polar researcher
early 20th century
developed theory of continental drift
idea: continents were once connected (Pangaea)
What is a hotspot?
fixed heat source in mantle
magma rises through plate
volcanoes form away from plate boundaries
chain of volcanoes possible
Explain how an earthquake occurs.
sudden release of energy
movement along faults
seismic waves
Which plate movement is responsible for earthquakes along the west coast of South America?
convergent plate movement
destructive plate boundary
subduction
oceanic plate beneath continental plate
What's the difference between magma and lava?
magma: below surface
lava: on surface
Name the three main layers of the Earth and their order.
crust
mantle
core
What are the effects of converging plate movement?
subduction or continental collision
earthquakes
volcanoes (at subduction zones)
mountain building
deep-sea trenches
When is an earthquake considered a natural disaster?
causes major damage
affects people and infrastructure
leads to deaths or economic loss
What were the secondary effects that increased the severity of the 2011 Japan disaster.
tsunami
flooding of coastal areas
Fukushima nuclear disaster
radiation release
evacuation and long-term exclusion zones
Name two characteristics of shield volcanoes.
flat shape
effusive eruptions
thin lava
Explain the difference between continental drift and plate tectonics.
continental drift: continents move
plate tectonics: plates move
includes oceanic crust
driven by mantle processes
Explain the three different types of plate boundaries.
constructive → plates move apart
destructive → plates collide
conservative → plates slide past
Difference between hypocentre and epicentre?
hypocentre: focus underground
epicentre: point on surface above
Name two reasons why the Haiti earthquake in 2010 became a more severe natural disaster than the one in Chile.
weak building standards
poorly constructed infrastructure
limited emergency response
lower level of economic development
Explain the difference between shield and composite volcanoes.
shield: effusive, low risk
composite: explosive, high risk
Explain the roles of lithosphere and asthenosphere.
lithosphere: rigid plates
asthenosphere: soft
plates float and move on asthenosphere
Explain seafloor spreading.
occurs at constructive boundaries
magma rises
new oceanic crust forms
plates move apart
What's the difference between primary and secondary effects? (Also give examples.)
primary: direct effects
casualties
secondary: indirect effects
Why can a strong earthquake cause fewer deaths in a high-income country?
earthquake-resistant buildings
early warning systems
emergency response
Why are composite volcanoes more dangerous?
explosive eruptions
ash clouds
pyroclastic material
Explain how convection currents lead to plate movement.
heat from core
hot material rises
cool material sinks
movement transfers to plates
Explain what exactly happens at subduction zones.
two plates converge
denser (oceanic) plate sinks
plate moves into mantle
trench forms
earthquakes
volcanoes possible
Why do some regions have a higher risk of being severely affected by a natural disaster than others?
exposure vs. vulnerability
building standards
preparedness
governance
Two countries have similar earthquake exposure. Predict which one will suffer more damage and why.
country with higher vulnerability
poorer building quality
weaker emergency systems
Discuss the pros and cons of living near a volcano.
advantages: fertile soil, tourism, energy
disadvantages: eruptions, hazards
risk depends on volcano type & preparedness