Key Terms: Tectonic Hazards Flashcards
All 11 cards in this deck
What is a plate margin?
The boundary where two tectonic plates meet.
What happens at a constructive plate margin?
Two plates move apart and magma rises into the gap to form new crust, giving gentle volcanoes and weak earthquakes.
What happens at a destructive plate margin?
Two plates move towards each other and the denser oceanic plate is subducted beneath the continental plate, giving strong earthquakes and explosive volcanoes.
What happens at a conservative plate margin?
Two plates slide past each other; no crust is created or destroyed, and earthquakes are caused as the plates jerk past.
What is subduction?
Where a denser oceanic plate sinks beneath a less dense continental plate at a destructive margin and melts.
What is a convection current (in the mantle)?
A circular movement of heat in the mantle that helps to move the tectonic plates above it.
What is the focus of an earthquake?
The point inside the Earth where the earthquake originates.
What is the epicentre of an earthquake?
The point on the Earth's surface directly above the focus.
What is the magnitude of an earthquake?
The size or strength of the earthquake, measured on the moment magnitude (or Richter) scale.
What is a tsunami?
A series of large waves caused by water being displaced, usually by an underwater earthquake.
True or false? Volcanoes are found at conservative plate margins.
False. Plates only slide past each other there, so no magma reaches the surface — conservative margins cause earthquakes.