BUENOS AIRES (Reuters) - An abnormal sound detected in the South Atlantic ocean around the time that an Argentine navy submarine sent its last signal last week was  consistent with an explosion,  a navy spokesman said on Thursday.  Spokesman Enrique Balbi described the blast in the morning of Nov. 15 as  abnormal, singular, short, violent  and  non-nuclear.  A huge sea and air hunt is being conducted for the ARA San Juan, which went missing with 44 crew on board. 
Event 'consistent with an explosion' detected near missing Argentine sub-navy