Rewinding the waves: tracking underwater signals to their source

Area of Science:

• Geophysics
• Acoustics
• Oceanography

Background:

• Hydroacoustic data from March 8th, 2014, revealed unique pressure signatures at Comprehensive Nuclear-Test-Ban Treaty Organisation stations.
• These signatures resemble those of objects impacting the sea surface, potentially including meteorites or Malaysia Airlines Flight 370.
• Experiments with water tank impacts confirmed the signature structure associated with impacting objects.

Purpose of the Study:

• To develop an analytical inverse method for retrieving impact time and location using acoustic-gravity wave theory.
• To analyze unique pressure signatures recorded by hydroacoustic stations.
• To validate the method's accuracy for various geophysical events.

Main Methods:

• Analysis of hydroacoustic data from Comprehensive Nuclear-Test-Ban Treaty Organisation stations.
• Controlled experiments simulating object impacts on a water surface.
• Application of acoustic-gravity wave theory for an inverse method.
• Validation using field observations of earthquakes and numerical simulations.

Main Results:

• Identified unique pressure signatures characteristic of sea surface impacts.
• Developed and validated an analytical inverse method to determine impact time and location.
• Achieved high accuracy (error <0.02% for distances >1000 km) in validations.
• Demonstrated successful application to earthquake eruption time and location.

Conclusions:

• The developed method accurately determines the impact time and location of sea surface events.
• The technique shows potential for identifying underwater explosions and landslides.
• Further development could enable calculation of impact duration and geometry.
• This acoustic analysis offers a novel approach to understanding oceanic events.