Earthquake Engineering MCQ with answer and solution

Concept

Characteristics of Richter seismic magnitude scale

Formula

M_L = log₁₀(A) - log₁₀(A₀)

Step-by-step solution

1. The Richter scale was devised by Charles Richter to quantify earthquake magnitude. 2. The scale is mathematically logarithmic (base 10), where each whole number step represents a 10-fold increase in measured amplitude. 3. In terms of radiated seismic energy, each whole magnitude unit corresponds to approximately 10^1.5 (approx 31.6) times more energy. 4. Thus, the Richter scale is a logarithmic scale measuring energy. Answer: B

Explanation

The Richter magnitude scale is a base-10 logarithmic scale that quantifies the total seismic energy released at an earthquake's focus based on seismograph wave amplitudes. Each unit increase represents a ten-fold increase in amplitude and roughly 31.6 times more energy.

Why the other options are wrong

A) The Modified Mercalli Intensity scale measures observable surface damage, not Richter. C) Ground displacement alone is amplitude, whereas Richter converts amplitude logarithmically. D) Duration-based scales are separate specialized seismic metrics.

Shortcut

Richter = Logarithmic energy scale; Mercalli = Linear damage/intensity scale.

Common mistake

Confusing Richter magnitude (energy released) with Mercalli intensity (physical surface damage).