Here, data from NCEDC.org and the USGS and UC Berkeley have been sliced out into veneers based on magnitude, then glued onto and image that began it's life at NASA's Visual Earth and wrung into the Times projection (centered at the interesting bits). The result looks an awful lot like a fleet of Nickelodeon tankers spilled the world's supply of floam.
If historical epicenters were floaties, you could walk from Seattle to Wellington.
We only started recording hard core in the late 1960's. Also, you'd be right to assume that areas with more sensors record more earthquakes (but that's why they are there, so round and round we go), though they can pretty well pinpoint epicenters from all over.
You can order a poster print of this map than you should then mount within a flexible frame with unanchored pliable wall brackets behind shatterproof glass.
Same Thing, Different Perspective
Alternatively, here is the same data set duplicated in both north and south polar projections...