On April 11, 2012, two earthquakes were measured off the northwest coast of Sumatra. The first had a magnitude of 8. 6. The second had a magnitude of 8. 2. By what approximate factor was the intensity of the first earthquake greater than the intensity of the second earthquake? mc020-1. Jpg M = the magnitude of an earthquake I = the intensity of an earthquake I0 = the smallest seismic activity that can be measured, which is 1 0. 40 1. 02 01. 05 02. 51.