The magnitude, M, of an earthquake is defined to be M = log StartFraction I Over S EndFraction, where I is the intensity of the earthquake (measured by the amplitude of the seismograph wave) and S is the intensity of a "standard" earthquake, which is barely detectable. Which equation represents the magnitude of an earthquake that is 10 times more intense than a standard earthquake? M = log StartFraction I Over S EndFraction M = log (10 S) M = log StartFraction 10 S Over S EndFraction M = log StartFraction 10 Over S EndFraction.