Which statement describes the Richter Scale?

• A. Measures the magnitude based on ground motion amplitude
• B. Measures the damage it causes
• C. Measures the time of arrival of seismic waves
• D. Measures the depth of the focus

Answer: (A)

Understanding how earthquake magnitude is quantified helps explain this. The Richter Scale assigns magnitude based on the amplitude of ground shaking recorded by a seismograph, with adjustments to compare events at different distances from the epicenter. Bigger amplitudes indicate a stronger quake, so the magnitude rises with stronger shaking. It does not measure damage, which depends on factors like distance from the epicenter, geology, and building design. It also isn’t about when seismic waves arrive or how deep the earthquake originated; those aspects relate to locating the event and its depth, not its magnitude. So the description that the scale measures magnitude based on ground motion amplitude is the best fit.