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. Last Updated: 07/27/2016

U.S. Research Indicates Blast Sunk Kursk

ALBUQUERQUE, New Mexico - Seismic analysis of shock waves suggests two successive onboard explosions, not a collision, destroyed a Russian submarine in August, killing all 118 sailors aboard, a new report says.

The first explosion was relatively small, consistent with a misfiring torpedo aboard the submarine Kursk, according to a report by Arizona and New Mexico researchers published Tuesday in the geophysical journal Eos. That blast was followed about two minutes later by a second blast 250 times larger than the first, the researchers said.

"The size of the second explosion was so great that it is unlikely any submariners could have survived the corresponding pressure pulse," their study says.

The Kursk sank Aug. 12 in the Barents Sea.

Most investigators have said they believed an explosion sank it, but Russian researchers have left open the possibility that there was a collision - possibly with a ship shadowing the sub.

The Eos authors, led by Keith Koper and Terry Wallace of the University of Arizona, say their seismic data were collected by a network of seismic stations used in part to monitor a Russian nuclear test site 800 kilometers from the Kursk.

Los Alamos National Laboratory scientists Steve Taylor and Hans Hartse participated in the study, entitled "Forensic Seismology and the Sinking of the Kursk."

The explosions sent shock waves to the ocean floor, where they registered on seismometers, they reported.

"The main shock is consistent with the explosion of approximately 5 tons (4.5 metric tons) equivalent TNT detonated near, or on, the sea floor," they wrote.

They said the initial shock "presumably disabled the Kursk and caused it to sink to the sea floor where ... the main explosion occurred."

The first blast was consistent with "a misfire or premature detonation of a torpedo," they wrote, noting that the sub had radioed for permission to fire ordnance shortly before the initial blast.

The second blast was likely caused by fire from the first blast spreading to other warheads or propellant fuel, Wallace said Tuesday by e-mail from Chile, where he and Koper are doing other research.

"We do not believe that the second event was caused by impact," he said. "Although impact may have contributed to the (seismic) signal, it is dominated by the fingerprint of an explosion."

Taylor, reached in Los Alamos, said the research team is not suggesting either blast was a nuclear explosion. The report refers only to conventional explosives.

The team used a few seismic stations in northern Finland, northern Russia and in Norway to trace the shock waves, Taylor said.

In December, an American who worked on the Kursk recovery team said damage he saw convinced him the sub blew up.

"From what I saw, it was obvious it exploded," Don Degener said from his home near Kansas City.

A Russian commission investigating the sinking has reached no conclusion but is considering three possibilities: an accident in the torpedo bay, a collision and a World War II mine.

The U.S. Navy denies involvement in the incident.

"All along, the United States Navy has insisted there was no such collision with our vessels," Lieutenant Meghan Mariman, a Navy spokeswoman, said Tuesday at the Pentagon.

Vice Admiral John Grossenbacher said last month the U.S. submarines Memphis and Toledo had been in the area but were not involved.

"I'm the senior submarine commander in the United States Navy and I know where all of our submarines are at any time. I know what they're all doing and why they're doing it," said Grossenbacher. "They had absolutely nothing to do with the tragedy that occurred on the Kursk."

The two American subs were there to collect data on Russian naval exercises.