The intensity (I) of each earthquake was different. Let I1 represent the intensity the early earthquake and I2represent the latest earthquake.
egin{eqnarray*}&& \
First &:&8.3=log displaystyle frac{I_{1}}{S} \
&& \
Second &:&7.1=log displaystyle frac{I_{2}}{S} \
&& \
&&
end{eqnarray*}
What you are looking for is the ratio of the intensities: $displaystyle frac{I_{1}}{
I_{2}}.$ So our task is to isolate this ratio from the above given information using the rules of logarithms.
egin{eqnarray*}log displaystyle frac{I_{1}}{S}-log displaystyle frac{I_{...
...og displaystyle frac{I_{1}}{I_{2}} &=&1.2 \
&& \
&& \
&&
end{eqnarray*}
Convert the logarithmic equation to an exponential equation.
egin{eqnarray*}&& \
log displaystyle frac{I_{1}}{I_{2}} &=&1.2 \
&& \ ...
...\
displaystyle frac{I_{1}}{I_{2}} &approx &16 \
&& \
&&
end{eqnarray*}
The early earthquake was 16 times as intense as the later earthquake.