The open section of the stern of the sunken frigate Cheonan, which was raised by a floating crane and placed on a barge Thursday, appears to have been ripped apart upward by an external explosion. It was covered by nets to prevent bodies or debris from falling out of the wreckage. / Joint Press Corps
By Lee Tae-hoon
Experts said Thursday a powerful external explosion is the likely cause of the sinking of the naval ship Cheonan in the West Sea as the broken section of its stern part appears to have been ripped apart and the severed edges appear badly damaged.
They said the explosion seems to have occurred underwater, below the 1,200-ton warship, as the upper metal structure of the warship was bent upward by a ``bubble jet`` effect.
They said the possibility of a metal fatigue fracture or an implosion is slim, claiming that the ship appears to have been torn into two parts as a result of a torpedo or a sea mine exploding underwater.
Analysts agreed that an internal blast is an unlikely cause, given that most of the weapons on the frigate, including 76mm and 40mm guns under which ammunition is stored, remain intact.
Military authorities say they are keeping all options open and have also ruled out the possibility of a metal fatigue fracture, saying if that were the cause, the vessel would have split more evenly in two, rather than been torn apart. .
Military officials have urged people not to make rash judgments as a joint investigation team of civilian, military and multinational experts are analyzing the wreck to verify the exact cause of the tragedy.
Navy ships equipped with sonar and underwater camera systems have been searching for debris from the Cheonan and shrapnel from the explosion to identify the type of weapons detonated.
International experts ― eight from the United States and three from Australia ― have arrived to contribute to the investigations to ensure transparency and objectivity.
As the possibility of an external explosion is high, the hypothesis of Pyongyang's involvement in the maritime disaster is gaining momentum.
Earlier, Defense Minister Kim Tae-young said in a National Assembly session that a torpedo could have caused the blast, though all possibilities needed to be considered.
Some say an explosion from a mine placed either by South or North Korea during the 1950-53 Korean War or one that floated down from the North could also have been the cause.
The communist North has made no official comment on the incident.