ARA San Juan

This has been out there for a bit, but it just came across my twitter feed and I thought it was worth passing on:

• That acoustic signal originated near 46-10S, 59-42W at 1358Z (GMT) on 15 November 2017. It was produced by the collapse (implosion) of the ARA SAN JUAN pressure-hull at a depth of 1275-feet. Sea pressure at the Collapse depth was 570 PSI. The frequency of the collapse event signal (bubble-pulse) was about 4.4 Hz.
• The energy released by the collapse was equal to the explosion of 12,500 Pounds of TNT at a depth of 1275-feet. That energy was produced by the nearly instantaneous conversion of potential energy (sea-pressure) to kinetic energy, the motion of the intruding water-ram which entered the SAN JUAN pressure-hull at a speed of about 1800 mph.
• The entire pressure-hull was destroyed (fragmented/compacted) in about 40 milliseconds (0.040s or 1/25th of a second), the duration of the compression phase of the collapse event which is half the minimum time required for cognitive recognition of an event.
• Although the crew may have known collapse was imminent, they never knew It was occurring. It is reasonable to assume the sailors did not drown or experience pain. Death was instantaneous.
• The SAN JUAN wreckage sank vertically at an estimated speed between 10 and 13 knots. Bottom impact would not have produced an acoustic event detectable at long range.