The tragic West, Texas fertilizer factory explosion resulted in seismic activity of magnitude 2.1. The explosion was the latest non-earthquake news event to generate seismic activity, and it put it on par with the collapse of the South Tower of the World Trade Center in terms of seismic activity generated. A chart of selected events is below:

Source:  USGS; Columbia University

As noted by the USGS, “The magnitude measures only the ground motion, not the air wave, so is substantially less than the true size of the event.”

Details are below:

• 2013 Nuclear Test – North Korea:  5.1 (2/12/13, 11:57 AM local time)
• 2009 Nuclear Test – North Korea:  4.7 (5/25/09, 9:54 AM local time)
• 2006 Nuclear Test – North Korea:  4.3 (10/9/06, 10:35 AM local time)
• 2001 World Trade Center North Tower collapse:  2.3 (9/11/01, approx. 10:28 AM local time)
• 2001 World Trade Center South Tower collapse:  2.1 (9/11/01, approx. 9:59 AM local time)
• 2013 West, Texas Factory Explosion:  2.1 (4/17/13, 7:50 PM local time)