Small ' hot spot ' responsible for producing the largest concentration of the greenhouse gas methane emitted over the United States . land near the Four mile border of Arizona , Colorado , New Mexico and longitude covers 180 square miles . Hotspot predates widespread fracking in the area .
Small 'hot spot ' responsible for producing the largest concentration of the greenhouse gas methane seen over the United States . Area near the Four Corners intersection of Arizona , Colorado , New Mexico and Utah covers 2,500 square miles . Hotspot predates widespread fracking in the area .