The problem describes how the Richter scale magnitude, $R$, of an earthquake is determined. The formula is given by $R = \log(\frac{a}{T}) + B$, where $a$ is the amplitude of the vertical ground motion (in micrometers), $T$ is the length of time a seismic wave lasts, and $B$ is a factor that accounts for the weakening of the seismic waves.

1. Problem Description

The problem describes how the Richter scale magnitude, $R$, of an earthquake is determined. The formula is given by $R = \log(\frac{a}{T}) + B$, where $a$ is the amplitude of the vertical ground motion (in micrometers), $T$ is the length of time a seismic wave lasts, and $B$ is a factor that accounts for the weakening of the seismic waves.

2. Solution Steps

The given formula is:

$R = \log(\frac{a}{T}) + B$

The problem only asks us to restate the formula and explain the variables. There are no computations to perform.

3. Final Answer

The Richter scale magnitude $R$ is calculated using the formula $R = \log(\frac{a}{T}) + B$, where $a$ is the amplitude of the vertical ground motion, $T$ is the length of time the seismic wave lasts, and $B$ is a factor that accounts for the weakening of seismic waves.