India’s National Institute of Ocean Technology (NIOT), in its Ministry of Earth Sciences (MoES), has designed and tested a submerged tsunami buoy system as an alternative to conventional DART surface tsunami buoy system currently used globally. The International Tsunameter Partnership (ITP), a Task Team under the Data Buoy Cooperation Panel, has been coordinating the technological development of submerged tsunameters and has developed best practice method for its use and coordinated the sharing of water level data with NOAA National Data Buoy Center.
NIOT is engaged in the establishment and maintenance of the Data and Tsunami Buoy Network for measurement of met-ocean parameters and tsunami warning in Indian waters. As part of those activities, it developed the submerged tsunami buoy to provide reliable warnings to the coastal communities. The conventional deep ocean tsunami buoy system consists of surface buoys that float on the sea surface and thus are prone to wear and tear, fouling, damages due to vandalism and harsh marine environments, cyclone, etc. This heightens the risks of missing warning messages during a tsunami event. To overcome these constraints a power-efficient and cost-effective, vandalism-free, reliable and environment-friendly subsurface moored buoy system namely CHATUR (Continuously Homing submerged Autonomous Tsunami UnderwateR system) was developed.
CHATUR buoys remain subsurface at an approximate depth of 300 metres. The buoys ascend to the surface when a tsunami message from the Bottom Pressure Recorder (BPR) is detected. As the buoy ascends, the antenna transmits the data to a shore station. The system floats on the sea surface in the watch circle area, then after a predefined time, the buoy sinks back down to its homing depth using underwater winch systems. The bottom part follows a taut mooring with acoustic release connected to the anchor.
The system has been tested in the field in both the Arabian Sea and the Bay of Bengal, using Ocean Research Vessel Sagar Kanya and Sagar Nidhi respectively. The CHATUR’s reliability assessment, using numerical methods, was published in the Journal of Marine Technology Society. An article was also published daily Times of India on 25 March 2021.