A truck carrying ammonium nitrate exploded shortly after 7am Wednesday morning near Camden, Arkansas.
The explosion was heard for miles and even measured seismically.
This is the helicorder located at White Oak Lake Arkansas and maintained by the Arkansas Geological Survey and the University of Memphis.
The large black movements show the seismic activity at the time of the explosion; shortly after 7am.
White Oak Lake is located roughly 20 miles to the northwest of where the explosion occurred.
The explosion left a 15ft crater in Arkansas Highway 287 which remains closed.
The sound wave traveled a longer distance due to the cold air at the surface this morning and the warmer air above us which kept the wave trapped near the boundary layer of the Earth.
The blast wave propagated much like thunder.
Sound wave took:
16min to arrive at Little Rock
29min to travel to Fort Smith.
40min to Fayetteville.
The explosion occurred shortly after 7am. Ammonium nitrate was the same substance used in the Oklahoma City Bombing in 1995. The substance is primarily used as a fertilizer.