Daytona Beach … A mysterious “earthquake” detected off the Florida coast over the weekend was actually the result of testing by the U.S. Navy, U.S. Geological Survey officials say.
Seismographs as far away as Minnesota, Texas and Oklahoma registered a 3.7 magnitude event around 4 p.m. Saturday, about 168 nautical miles east-northeast of Daytona Beach Shores, the Daytona Beach News-Journal reported.
But it appears those readings were triggered by a manmade explosion designed to test the seaworthiness of a new U.S. Navy vessel, the USS Jackson.
A spokesperson told the News-Journal that the Navy is working on a statement it expects to release this week, but according to geophysicist Bruce Presgrave, a large underwater explosion “would almost certainly be detected as an earthquake.”
During a June 10 shock test on the Jackson, a 10,000-pound explosive charge was set off about 100 yards from the ship, Defense News reports. That same day, the USGS reported a 3.7 magnitude event similar to the one that occurred over the weekend, the News-Journal said.
The Navy informed NOAA’s National Marine Fisheries Service that another shock trial would be conducted between July 16 and 20, according to the Tampa Bay Times.
Shock trials help to “demonstrate the ship’s ability to withstand an explosion,” Capt. Thurraya Kent, a spokesperson for the Navy’s acquisition directorate, told Defense News.
About 260 instruments are placed throughout the ship to measure various aspects of the blast, which strikes above and below the water. The ship’s crew of about 50 and a number of engineers and observers are usually on board during tests.
Commissioned last December, the Jackson came through the first test with only minor damage, according to Kent, such as items falling to the deck or glass cracking.
The Jackson is one of is one of the Navy’s new Independence class of littoral combat ships, which will conduct anti-submarine, surface and mine countermeasure operations around the globe.