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Verification Technologies: Hydroacoustics

Hydroacoustic network

  • Hydroacoustic monitoring detects acoustic waves produced by natural and man-made phenomena in the oceans.

  • The CTBT hydroacoustic network comprises eleven stations and covers the world's oceans, which make up 70% of the surface area of the earth.

  • Few stations are required because of the very efficient propagation of acoustic energy in the oceans.

  • The network comprises two different types of stations: "hydrophone" stations and "T-phase" (seismic) stations.

  • The CTBT's six hydrophone stations use underwater microphones (hydrophones) that capture signals underwater and then transmit them via cable to the shore station. Hydrophone stations are extremely sensitive and pick up acoustic waves from underwater events, including explosions, occurring very far away.

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Ship laying cable for hydroacoustic station HA04, located off the Crozet Islands (the cable-laying process was carried out without disturbing the penguins)
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Ship laying cable for hydroacoustic station HA08 (hydrophone), located in British Indian Ocean Territory
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Diagram depicting the layout of a hydroacoustic station
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  • Such stations are expensive to install and costly to maintain, so the network also consists of five T-phase (seismic) stations. These stations are located on oceanic islands and use seismometers to detect the acoustic waves that are converted to seismic waves when they hit the island.

  • The data from the hydroacoustic stations are used in the verification system to distinguish between underwater explosions and other phenomena, such as sub-sea volcanoes and earthquakes, which also propagate acoustic energy into the oceans.