Question

The 1906 San Francisco earthquake had a magnitude of 7.9 on the MMS scale. Around the same time there was an earthquake in South America with magnitude 6.5 that caused only minor damage. How many times more intense was the earth movement in San Francisco earthquake than the South American one?

Answer 1

25.1

Explanation:

The Richter scale is logarithmic, meaning that each whole number increase on the scale represents a tenfold increase in the amplitude of ground motion.

To find the difference between the two earthquakes, we subtract the magnitude of the South American earthquake from the magnitude of the San Francisco earthquake:

7.9 - 6.5 = 1.4

Since each whole number increase represents a tenfold increase in intensity, a 1.4 magnitude difference indicates that the San Francisco earthquake was approximately 25.1 (10^1.4) times more intense than the South American earthquake.