The Indian Ocean Tsunami (December 26, 2004) has been one of the strongest in the world and the deadliest of all time by an order of magnitude. Driven by this national calamity, the Government of India decided to put in place an Early Warning System for mitigation of such oceanogenic disasters. Indian National Center for Ocean Information Services (INCOIS), Hyderabad was given the responsibility to coordinate the entire project and make it operational
The Indian Tsunami Early Warning System comprises a real-time network of seismic stations, Bottom Pressure Recorders (BPR), tide gauges and 24 X 7 operational tsunami warning centre to detect tsunamigenic earthquakes and to monitor tsunamis and to provide timely advisories to vulnerable community by means of latest communication methods with back-end support of scenario database, vulnerability modelling and Decision Support System.
The Early Warning System has the following components
A dedicated Tsunami Warning Centre operating on 24x7 basis for generation of timely advisories
A network of land-based seismic stations for earthquake detection and estimation of focal parameters in the two known tsunamigenic zones and to communicate the same to the Early Warning Centre in near-real time
A network of 12 bottom pressure recorders (that could detect and measure a change in water level of 1 cm at water depths of up to 6 km of water) to detect and monitor tsunami around these two tsunamigenic zones
Real-time observational network for upper ocean parameters and surface met-ocean parameters, especially in the areas of cyclogenesis and coastal sea, for improving forecast of Storm Surges
A network of 50 real time tide gauges, radar-based coastal monitoring stations and current meter moorings to monitor progress of tsunami and storm surges
Generation of high resolution data base on bathymetry, coastal topography, coastal land use (for costal areas within 1-3 km in general and for 10-25 km at selected areas near coastal water bodies)
Coastal vulnerability modelling & Inundation mapping
Capacity building, training and education of all stake holders on utilisation of the maps, warning and watch advisories.
A state-of-the-art early warning centre is established with all the necessary computational and communication infrastructure that enables reception of real-time data from all the sensors, analysis of the data, generation and dissemination of tsunami advisories following a standard operating procedure. Seismic and sea-level data are continuously monitored in the Early Warning Centre using a custom-built software application that generates alarms/alerts in the warning centre whenever a pre-set threshold is crossed. Tsunami warnings/watches are then generated based on pre-set decision support rules and disseminated to the concerned authorities for action, following a Standard Operating Procedure. The efficiency of the end-to-end system was proved during the large under-sea earthquake of 8.4 M that occurred on September 12, 2007 in the Indian Ocean. It has taken two-and-half years to establish the Indian tsunami early warning system that was inaugurated on October 15, 2007.
The Early Warning Centre receives real-time Seismic data from the national seismic network of the Indian Meteorological Department (IMD) and other International seismic networks. The system detects all earthquake events of more than 6 Magnitude occurring in the Indian Ocean in the less than 12 minutes of occurrence. BPRs installed in the Deep Ocean are the key sensors to confirm the triggering of a Tsunami. The National Institute of Ocean Technology (NIOT) has installed 4 BPRs in the Bay of Bengal and the 2 BPRs in Arabian Sea. In addition, Survey of India (SOI) and NIOT have installed 30 Tide Gauges to monitor the progress of tsunami waves. Integrated Coastal and Marine Area Management (ICMAM) has customised and ran the Tsunami Model for 5 historical earthquakes and the predicted inundation areas. The inundated areas are being overlaid on cadastral level maps of 1:5000 scale. These community-level inundation maps are extremely useful for assessing the population and infrastructure at risk. High-resolution Coastal Topography data required for modelling is generated by the National Remote Sensing Centre (NRSC) using ALTM and Cartosat Data. INCOIS has also generated a large database of model scenarios for different earthquakes that are being used for operational tsunami early warning.
Communication of real-time data from seismic stations, tide gauges and BPRï¿½s to the early warning centre is very critical for generating timely tsunami warnings. A host of communication methods are employed for timely reception of data from the sensors as well as for dissemination of alerts. Indian Space Research Organisation (ISRO) has made an end-to-end communication plan using INSAT. A high level of redundancy is being built into the communication system to avoid single point failures.
The National Early Warning Centre will generate and disseminate timely advisories to the Control Room of the Ministry of Home Affairs for further dissemination to the Public. For the dissemination of alerts to MHA a satellite-based virtual private network for disaster management support (VPN DMS) has been established. This network enables early warning centre to disseminate warnings to the MHA, as well as to the State Emergency Operations Centres. In addition, Messages will also be sent by Phone, Fax, SMS and e-mails to authorised officials. In case of confirmed warnings, the National Early Warning Centre is being equipped with necessary facilities to disseminate the advisories directly to the administrators, media and public through SMS, e-mail, Fax, etc. The cyclone warning network of IMD and electronic ocean information boards of INCOIS could be effectively used for dissemination of warnings directly to the public.