Nomogram for the Gutenberg-Richter earthquake occurence relation

A nomogram for the Gutenberg-Richter relation: log N=a-b M, where N is the number of earthquakes, M is the magnitude and a and b are empirical coefficients (b is generally around 1 for most regions and datasets).

Draw a straight line from one axis and when it hits the diagonal axis for the required 'a' value travel perpendicular until the intersection with the other axis. For example, if you want to see how many magnitude 6 earthquakes there are assuming a=4 and b=1, go vertically from M=6 on the x axis until the intersection with the a=4 diagonal line and then read across to find N=0.01.

Created using pynomo using a type 5 nomogram.