The Richter scale magnitude, R, of an earthquake of intensity I is defined as R= log (I/IO), here IO is a small threshold intensity. Find the magnitude of an earthquake with intensity 40,000,000IO

The Richter scale magnitude, R, of an earthquake of intensity I is defined as R= log (I/IO), here IO is a small threshold intensity. Find the magnitude of an earthquake with intensity 40,000,000IO