How many times greater was the intensity of the 2011 earthquake?

Question

The intensity levels I of two earthquakes measured on a seismograph can be compared by the formula

 

log(I1I2)=M1−M2

 

using the common (base 10) logarithm and where M is the magnitude given by the Richter Scale. In August 2009, an earthquake of magnitude 6.1 hit Honshu, Japan. In March 2011, that same region experienced yet another, more devastating earthquake, this time with a magnitude of 9.0.^[1] How many times greater was the intensity of the 2011 earthquake?

Answer 1

log(i|2)=M1-M2

Assuming these are intensity comparisons, then

M1 / M2 = 10^(9.0-6.1) = 10^(2.9)

M1 / M2 = 794, although this suggests more accurate

determination of the intensity that is likely.

Almost 10^3 times greater, a thousand times greater.