Why is there a huge methane hotspot in the American Southwest?

[happyslug]

7. You forgot the note with the map, showing dark for Methane, light almost no methane

This image shows methane hotspot, highlighted in red, in the Four Corners area. This map shows how much methane emissions varied from average background concentrations from 2003-2009 (dark colors are lower than average; lighter colors are higher. (AP Photo/NASA, JPL-Caltech, University of Michigan)

A map without saying what the colors mean is meaningless, i.e. Northern California gives off little methane, but Texas gives up a lot. The coal Country of Southern Illinois to Southwestern PA gives off a good bit, but as you go further east, south and north, methane production declines.

One more comment, the yellow dot in Southwestern PA looks like Washington County PA, a hot spot for Natural Gas (Methane) from the Marcellus shell. Washington County is where they are presently mining the Pittsburgh Seam of coal, and coal is noted for methane pockets.