Aren't there only four?

I have friends who were in Istanbul at the time of the big earthquake two years ago. They will quite emphatically remind you that there is a big crack there between two continental plates. Turkey itself is a country situated on two continents. Also, the predictions about where the plates are moving indicate that in a couple of million years there will be no Turkey. It will be squashed underneath those other two plates. (Somewhere on the web there is probably a good picture. Here, try this map of earthquake frequency (red) and continental plates (yellow): http://atlas.gc.ca/english/quick_maps/image_collection/img_collection_view7_e.html)