Answer
1995.26 times more intense
Work Step by Step
Given the magnitude equation $M = \log \frac{I}{S}$
with $S = 10^{-4}$
The question asks for how much more intense the 2007 Japan earthquake (M = 6.4) was compared to the 2007 Pennsylvania Earthquake (M = 3.1)
S is a constant that is already factored into the Magnitudes, so the $10^{-4}$ isn't necessary
$(6.4- 3.1) = \log I$
$10^{3.3} = {I}$
$I = 1995.26$ times more intense
