Implosion in the Challenger Deep: Echo Sounding with the Shock Wave

Since HMS Challenger made the first sounding in Mariana Trench 1875, scientists and explorers have been seeking to establish exact location depth of deepest part ocean. The scientific consensus is that situated Deep, an abyss with depths greater than 10,000 m. Since1952, when II, following its namesake, returned Trench, 20 estimates (including one from this study) Deep made. are as diverse methods used obtain them; they range early measurements explosives stop watches, single- multi-beam sonars, submersibles, both crewed remotely operated. In December 2014, we participated expedition onboard Schmidt Ocean Institute’s R/V Falkor deployed two free-falling, passive-acoustic instrument platforms, each a glass-sphere pressure housing containing system electronics. At nominal 9,000 m, these housings imploded, creating highly energetic shock wave that, recorded by other instrument, reflected multiple times sea surface seafloor. From arrival multi-path pulses at surviving conjunction concurrent measurement sound speed profile water column, obtained constrained acoustic estimate Deep: 10,983 ± 6