... the threat of dangerous levels of ammonia fumes.

The ground motion from the explosion measured as a magnitude 2.1 earthquake,

reported the U.S. Geological Survey ,

and the shock waves in the air would have been substantially higher.

At least six ... Comment?

http://www.topix.com/county/mclennan-tx/2013/...

Related Topix: Explosion, Fire, Natural Disasters, US Geological Survey, Technical Services