gen-state-the-richter-and-moment-magnitude-scales-precisely-and-f815

State the Richter and moment magnitude scales precisely and explain why it matters in 2-3 sentences.

# Magnitude Scales **Richter Scale (ML):** Measures earthquake magnitude using the logarithm of maximum wave amplitude recorded on a Wood-Anderson seismograph at 100 km distance: ML = log₁₀(A) - log₁₀(A₀), where A is measured amplitude and A₀ is a standard reference. **Moment Magnitude Scale (Mw):** Calculates magnitude from seismic moment: Mw = (2/3)log₁₀(M₀) - 10.7, where M₀ = μ × A × D (shear modulus × rupture area × average slip). **Why it matters:** The Richter scale saturates above magnitude ~6.5-7 (cannot distinguish between very large earthquakes), while moment magnitude accurately measures all earthquake sizes and directly relates to the physical energy released. This is why modern seismology uses moment magnitude for all significant earthquakes—it provides consistent, physically meaningful measurements across the full range of possible earthquake sizes.