Which statement describes the Modified Mercalli Scale?

• A. Measures ground motion amplitude
• B. Measures damage
• C. Measures the magnitude
• D. Measures the speed of seismic waves

Answer: (B)

The Modified Mercalli Scale describes the observed effects and damage caused by an earthquake at a specific location. It grades shaking intensity on a scale from I to XII based on what people feel, what they observe, and the damage to buildings and infrastructure. Because it focuses on human perception and actual destruction rather than the energy released, it measures damage and impact rather than ground motion amplitude, magnitude, or wave speed. Magnitude is determined from seismograph data and reflects energy release, while ground motion and wave speeds are instrument-based measurements. This is why describing it as measuring damage is the best fit.