Question

What is the intensity of an earthquake with a magnitude of 3?

3 times a standard earthquake

100 times a standard earthquake

1,000 times a standard earthquake

3,000 times a standard earthquake

30,000 times a standard earthquake

Answer 1

It depends what you mean by “intensity.” On the Richter/log scale:

- Amplitude (ground motion) scales as 10^(ΔM). So M3 is 10^3 = 1,000 times the amplitude of an M0 quake (or 100× the amplitude of an M1 quake).
- Energy released scales as about 10^(1.5·ΔM). So M3 releases 10^(1.5·3) = 10^4.5 ≈ 31,600 ≈ 30,000 times the energy of an M0 quake (or 1,000× the energy of an M1 quake).

Given the choices, the closest match for energy compared with a “standard” (M0) quake is 30,000 times.