Plate Boundaries
Name the three main types of plate boundary
Destructive (convergent), constructive (divergent), and conservative (transform).
Name Earth's four internal layers from the outside in.
Crust, mantle, outer core, inner core.
Which seismic waves are fastest: P-waves, S-waves, or surface waves?
AP-waves.
What is the difference between a hazard and a disaster?
A hazard is a physical event with the potential to cause harm; it becomes a disaster when it overwhelms a community's ability to cope.
List any three characteristics used in a hazard profile.
Any three: magnitude, speed of onset, duration, areal extent, spatial predictability, frequency
At which type of boundary does one plate subduct beneath another?
A destructive (convergent) boundary.
Which layer is liquid, and which is solid: the outer core or inner core?
The outer core is liquid; the inner core is solid.
Which seismic waves cannot travel through liquid?
S-waves.
Name the three components on the pressure side of the PAR model.
Root causes, dynamic pressures, and unsafe conditions.
Which hazard in the pack usually has the most rapid onset with almost no warning?
Earthquakes.
Why can conservative boundaries cause powerful earthquakes but usually no volcanoes?
Plates slide past each other, friction builds stress, and its release causes earthquakes. There is no subduction or rising magma to generate volcanoes.
What is the lithosphere, and what lies beneath it?
The rigid crust and uppermost mantle; it sits above the semi-molten asthenosphere.
What does the Benioff zone reveal about a subducting plate?
It traces the sloping zone of earthquake activity as the plate descends; earthquakes become deeper farther from the trench.
Give one social impact and one economic impact of a tectonic hazard.
Social examples: deaths, injuries, displacement, disease, trauma, disrupted education/healthcare. Economic examples: building damage, lost production, reduced tourism, insurance costs.
Which hazard can affect coastlines across an entire ocean basin?
A tsunami.
Give one example of a destructive boundary and identify the plates involved.
Example: the Andes, where the Nazca Plate subducts beneath the South American Plate; or Japan, where the Pacific Plate subducts beneath a neighbouring plate.
Explain how mantle convection helps move tectonic plates.
Heat from the core drives convection currents in the mantle, which help move plates.
Why is thick, high-viscosity magma more likely to produce an explosive eruption?
It traps gas, allowing pressure to build until it is released explosively.
Why might a wealthier country suffer greater economic losses but fewer deaths than a poorer country?
It may have more expensive assets and infrastructure to lose, but stronger building codes, preparedness, warning systems, and emergency response can reduce deaths.
How can hazard profiles help planners manage risk?
They allow hazards to be compared and help planners prioritise resources and management.
A location has shallow earthquakes and runny basaltic lava. Which boundary type is most likely, and why?
A constructive (divergent) boundary: plates move apart, magma rises, and low-viscosity basaltic lava tends to produce effusive eruptions.
What is sea-floor spreading, and name one piece of evidence that supports it.
Magma rises and solidifies at mid-ocean ridges to form new crust and push older crust apart. Evidence includes symmetrical magnetic stripes or progressively older rock farther from the ridge.
Compare P-waves, S-waves, and surface waves by speed and potential destructiveness.
P-waves are fastest and compressional; S-waves are slower shear waves and cannot travel through liquid; surface waves are slowest but generally most destructive.
Use the PAR model to explain how a natural hazard could become a disaster. Include an unsafe condition.
A hazard meets root causes, dynamic pressures, and unsafe conditions, increasing vulnerability and overwhelming the community's ability to cope. Example unsafe condition: poorly built housing or lack of early-warning systems.
A powerful earthquake occurs offshore at a destructive boundary. Link the plate process to a possible tsunami and explain why the resulting disaster may differ between two communities.
Subduction can generate an earthquake that suddenly displaces the sea floor, triggering a tsunami. The impacts depend not only on the hazard but also on vulnerability, preparedness, resilience, warning systems, and the communities' ability to cope.