Graph showing the annual average number of worldwide earthquakes of each magnitude calculated over the last 20 years. This shows how earthquake numbers decrease as magnitude increases. For example: there are roughly ten times as many earthquakes of magnitude 6 than magnitude 7.CLICK TO ENLARGE.n average there are about 15 earthquakes every year with a magnitude of 7 or greater. As with any almost random phenomena, the number of earthquakes each year varies slightly from this average, but in general, there are no dramatic variations.