Analysis of Hydroacoustic Signals Associated to the Loss of the Argentinian ARA San Juan Submarine

Abstract On November 15, 2017, an event related to the disappearance of Argentine military submarine ARA San Juan was detected by two hydrophone triplet stations IMS network, established enforce nuclear test ban treaty (CTBT). From direct hydroacoustic arrivals recorded at 6000 and 8000 km from localized wreckage, calculated location based on data only is poorly constrained, associated uncertainties are large. In attempt interpret signals, air dropped calibration grenade conducted Navy weeks later, December 1, near last known position submarine. comparison temporal spectral features both events, we confirm impulsive nature event. Array processing performed with a progressive multi-channel correlation method (PMCC). Fine propagation details very well resolved in time-frequency space thirteen secondary revealed for event, within fifteen minutes following arrivals. The detections presented this paper were DTK-PMCC software embedded NDC-In-A-Box virtual machine, can be reproduced any CTBTO principal user (Member State which access raw waveform bulletins). All identified late reflections or refractions seamounts, islands South American continental Slope. accurate identification all reflectors allows significantly improve source accuracy: 95% confidence ellipse area has been reduced factor 100 compared obtained only, estimated 3.5 wreckage. originality relocation that it joint inversion events unknown parameters, selection well-chosen subset Its calculation did not require either need advanced oceanographic specifications, sophisticated methods requiring heavy computational means. Finally, detailed cepstral analysis allowed detect existence second impulse (doublet) signals events. Unlike anisotropic character delays measured cepstra suggests 15 signal generated acoustic sources closely separated time over scales comparable size This study demonstrates capability component network accomplish its mission Comprehensive Nuclear-Test-Ban Treaty monitoring.