Richter Scale
A base-10 logarithmic scale quantifying earthquake magnitude based on the maximum amplitude of seismic waves recorded on a seismograph.
Governing formula
M_L = log₁₀(A / A₀), M_w = ⅔ log₁₀(M₀) - 6.07
SI unit
Logarithmic Magnitude (M_L / M_w)
In depth
Pioneered by Charles Richter in 1935. Each whole-number increase in Richter magnitude represents a 10-fold increase in measured wave amplitude and approximately a 31.6-fold (10^(1.5)) increase in released seismic energy. Modern seismology uses Moment Magnitude (M_w) based on seismic moment M₀.
Examples in the real world
A magnitude 7.0 earthquake releasing ~31.6 times more kinetic energy than a magnitude 6.0 earthquake.