An earthquake is defined as what?

• A. A slow drift of continents
• B. A sudden movement within the Earth's crust followed by a series of shocks
• C. A volcanic eruption
• D. A weather-related phenomenon

Answer: (B)

Quakes happen when stress in rocks near faults is released suddenly, causing rocks to snap and slip along faults. This rapid movement sends out seismic waves that shake the ground, and it’s common for aftershocks to follow as the crust readjusts. That fits the description of a sudden movement within the Earth's crust followed by a series of shocks.

The other ideas don’t fit: a slow drift of continents is plate tectonics over long timescales, not a rapid quake; a volcanic eruption involves magma movement and eruption, not just crustal rupture; weather-related phenomena involve atmospheric processes, not Earth's crustal movements.