Final answer:
The initial earthquake was approximately 31.6 times more intense than the aftershock.
Step-by-step explanation:
The intensity of an earthquake is related to its magnitude on the Richter scale. The Richter scale is logarithmic, meaning that each whole number increase on the scale represents an earthquake that is 10 times stronger in terms of energy release.
So, in this case, we can calculate the difference in intensity between the initial earthquake (magnitude 7.8) and the aftershock (magnitude 6.9) by finding the ratio of their energy releases.
To do this, we can use the following equation:
Intensity ratio = 10^((magnitude1 - magnitude2) * 1.5)
Plugging in the values, we get:
Intensity ratio = 10^((7.8 - 6.9) * 1.5) = 31.6227766 times
Therefore, the initial earthquake was approximately 31.6 times more intense than the aftershock.