Navy Shock Trial Mistaken for an Earthquake

Media in Florida reported Tuesday that a magnitude 3.7 earthquake recorded off of St. Augustine on July 16 was actually the intentional detonation of 10,000 pounds of explosives in a U.S. Navy "shock trial." 

The trial – the last in a series of three – was intended to test the resiliency of the Independence-class littoral combat ship USS Jackson. Dale Eng, Navy spokesman for the program, confirmed the blast. 

"On Saturday July 16, USS Jackson was subjected to the third and most forceful underwater explosion of her planned shock trials," he wrote in an emailed statement. "The ship performed exceptionally well, sustaining minimal damage and returned to port on her own power the following day to complete assessments."

The Navy notifies mariners in the area of an upcoming trial, but it was not immediately clear if it had notified shoreside authorities of its exact date; the blast was initially reported by local media as an earthquake.  

Earlier this month, following the first two shock trials, shipbuilder Austal said that costs for modifying the vessels to meet Navy shock standards would average roughly $10 million per hull.

"Design modifications and significant re-work of construction already undertaken are being implemented across the nine LCS vessels currently under construction. A $115 million one off write back of work in progress is required to recognize an increase in the cost of construction," the firm said. Austal did not specify the scope of work required for the change. 

The original block buy for the class put the cost per ship at roughly $350 million before the modifications.

The Freedom-class littoral combat ship USS Milwaukee, built by Lockheed Martin and Marinette, is scheduled to begin its own series of shock trials off the coast of Florida next month.