The Richter scale is logarithmic, meaning that each whole number increase on the scale represents a tenfold increase in measured amplitude and roughly 31.6 times more energy release.
To compare the two magnitudes:
- A magnitude 5.5 earthquake releases approximately \( 10^{(5.5)} \) times more amplitude than a reference level.
- A magnitude 7.5 earthquake releases approximately \( 10^{(7.5)} \) times more amplitude than the same reference level.
The difference in magnitude between 7.5 and 5.5 is 2.0 (7.5 - 5.5 = 2.0).
Since the scale is logarithmic, a difference of 2 in magnitude corresponds to:
- \( 10^2 \) (which is 100) times greater amplitude.
In terms of energy release, each whole number increase on the Richter scale represents about 31.6 times more energy—thus, a difference of 2 magnitudes (7.5 vs. 5.5) represents roughly \( 31.6^2 \) times more energy:
\[ 31.6 \times 31.6 \approx 1000 \]
So, a magnitude 7.5 earthquake is approximately 1000 times stronger in terms of energy release than a magnitude 5.5 earthquake.
Answer: 1000 times stronger.