There are more than 200 thousand earthquakes on the map, with data from 1898 to 2003. The Pacific "Ring of Fire" is visible near the center of the image, as is the Mid-Atlantic Ridge on the right.
Most quakes occur on fault lines, but there are instances of quakes happening away from fault lines.
The yellow colors on the map (best seen near Alaska, Japan, and New Zealand) are the strongest quakes with magnitudes above 8.0.
You won't see the colors from the strong earthquakes in Haiti (2010), Chile (2010), Japan (2011), and Indonesia (2004) because they are not included in the data.