Question

which statement describes one aspect of an earthquake’s magnitude?
○ it is measured by the mercalli scale.
○ it is based on the size of seismic waves.
○ it is not usually affected by the amount of fault movement.
○ it is used to determine damage caused by earthquakes.

Explanation:

• The Mercalli scale measures earthquake intensity (damage/effects), not magnitude. So the first option is wrong.
• Earthquake magnitude is related to the size (amplitude) of seismic waves. This matches the definition of magnitude (e.g., Richter scale uses seismic wave amplitude).
• Fault movement affects magnitude, so the third option is incorrect.
• Magnitude is about the earthquake's energy, while intensity (Mercalli) determines damage. So the fourth option is wrong.

Answer:

B. It is based on the size of seismic waves.