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Tectonic Hazards Flashcards
Free GCSE Geography Revision Cards
Cover plate boundaries, earthquake and volcanic processes, the impacts of tectonic hazards and how communities manage risk with these free Geography flashcards. Great for GCSE and A Level.
Question
What is plate tectonics?
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Answer
The theory that Earth's lithosphere is divided into large slabs (tectonic plates) that move slowly on the semi-molten asthenosphere — driven by convection currents in the mantle.
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Question
What are the three types of plate boundary?
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Answer
Constructive (divergent): plates move apart. Destructive (convergent): plates move together. Conservative (transform): plates slide past each other.
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Question
What happens at a constructive plate boundary?
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Answer
Plates pull apart; magma rises to fill the gap, forming new crust. Creates mid-ocean ridges (e.g. Mid-Atlantic Ridge), rift valleys, and shield volcanoes. Earthquakes are shallow and frequent.
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Question
What happens at a destructive plate boundary?
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Answer
A denser oceanic plate subducts beneath a continental plate (or two oceanic plates collide). Creates deep ocean trenches, explosive stratovolcanoes, fold mountains, and strong earthquakes.
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Question
What is subduction?
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Answer
The process where a denser (oceanic) tectonic plate is forced beneath another plate into the mantle — melting to form magma that rises as volcanoes. Creates the Pacific "Ring of Fire."
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Question
What is a conservative plate boundary and what hazard does it create?
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Answer
Plates slide past each other horizontally — no crust is created or destroyed. Creates powerful earthquakes (no volcanic activity). Example: San Andreas Fault (Pacific/North American plates).
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Question
What causes earthquakes?
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Answer
Sudden release of energy from rock stress built up where tectonic plates lock and then slip. The point of rupture underground is the focus (hypocentre); the point directly above on the surface is the epicentre.
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Question
What is the Richter scale vs the moment magnitude scale?
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Answer
Richter scale: measures earthquake energy on a logarithmic scale (each unit = 10× more ground movement). Moment magnitude scale (Mw) is now more widely used — both measure magnitude but Mw is more accurate for large earthquakes.
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Question
What is the Mercalli scale?
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Answer
Measures the intensity of an earthquake based on the damage caused and what people felt — not the energy released. It ranges from I (barely felt) to XII (total destruction).
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Question
What is a tsunami?
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Answer
A series of large ocean waves triggered by underwater earthquakes, volcanic eruptions, or landslides — displacing huge volumes of water. Waves travel at up to 800 km/h but grow in height as they reach shallow coastal water.
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