Earthquake: Test Your Understanding
Teacher's Guide
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What is an epicenter?
An epicenter is the point on Earth's surface directly above the onset of an earthquake.
Where and at what depths do most earthquakes occur?
Most earthquakes occur at depths shallower than about 50 km (30 mi) and are usually found near
plate boundaries.
Critical Thinking: Which type of plate motion would presumably cause a deeper earthquake: two plates
converging or two plates diverging? Explain your answer.
Sample answer: Surface rocks do respond to plate boundary movements. However, all surface rocks do
not shift at the same rate or direction as the plate. Instead, rocks respond with periodic, sudden elastic
movements to release frictional stress that builds up from plate movement through time.
Critical Thinking: Why don't all earthquakes happen simultaneously as a plate moves?
Sample answer: Buildings and other structures in such areas should have regulations to protect life
and property, such as being able to withstand shaking from long, intense earthquakes.
