A network of deep-water acoustic sensors providing early detection of tsunami waves for Indian coastal communities has undergone a major refurbishment.
Deployed at key locations in the Bay of Bengal and Arabian Sea over the past decade, the Sonardyne bottom pressure recorders (BPRs) detect the characteristic changes in water pressure (as little as one centimetre in 4,000 metres depth), caused by an earthquake in the deep ocean.
If a tsunami wave is detected, an alert message is transmitted to a satellite buoy on the surface, from where it is relayed to the Tsunami Warning Centre onshore for comparison with seismic activity. If validated, a wide-scale alarm is raised to alert vulnerable communities.
Conceived after the 2004 Boxing Day tsunami, the detection system is owned and operated by the Chennai-based National Institute of Ocean Technology (NIOT).
Data gathered by each BPR unit on an hourly basis has been used by scientists to develop understanding of the deep ocean and improve tsunami prediction models across the region.
NIOT's vessel visits the site of each sensor annually to carry out maintenance to the surface buoy and change the batteries inside each BPR – the deepest of which is in 4,000 metres of water.
After reaching the 10-year anniversary, NIOT decided to recover the BPRs one at a time and return them to Sonardyne's main service centre in the UK for refurbishment and re-certification.
This work included replacing acoustic transducers, calibrating pressure sensors, replacing consumables and updating PCB firmware to the latest specification.
