Families of the 43 men and one woman aboard ARA San Juan compared themselves to mourners at a wake as the disturbance was picked up by nuclear test monitors.
Search vessels and aircraft are now expected to concentrate their efforts near the site of the “impulsive event” off the coast of Argentina.
The 220-foot submarine vanished nine days ago after reporting an electrical breakdown as it returned to base from a routine military exercise.
The crew, which includes the Argentine navy’s first female submarine officer Eliana Maria Krawczyk, face running out of oxygen in the submerged TR-1700 vessel.
The “short, violent, non-nuclear event” was detected by the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), a Viennabased watchdog with a network of stations monitoring nuclear activity.
Mario Zampolli, a hydroacoustic engineer with the CTBTO, said: “It could be consistent with an explosion but there is no certainty about this.”
An Argentine navy spokesman confirmed the abnormal sound was “consistent with an explosion” – something the military were initially reluctant to discuss.
Elena Alfaro, whose brother Cristian Ibanez is a crew member, said outside the Mar del Plata base in Buenos Aires: “I feel like I’m waiting for a corpse. I feel like I’m at a wake.
“I also feel time passing, and time is crucial.
“I don’t want to bury my brother.”
Other relatives reacted angrily to the news, saying the navy had kept them in the dark during the past week.
“I feel cheated,” said Itati Leguizamon, whose husband is aboard the San Juan.
More than 4,000 personnel from 12 countries are now scouring the search zones, including the crews of the HMS Clyde and HMS Protector.
The Royal Navy has also dispatched its elite submarine rescue team.