Answer
$M_2=8.1$
Work Step by Step
The formula for Richter scale is,
$M=\log \frac{I}{S}$. Whereas, $I$ is the Intensity of Earthquake and $S$ is Intensity of "Standard" Earthquake.
$M_1=\log \frac{I}{S}=6.5$,
$M_2=\log \frac{35I}{S}=\log35+\log \frac{I}{S}=8.1$,
