India’s capability to transmit early warnings of a possible tsunami is all set to be further bolstered with a major facility being established in Andaman and Nicobar Islands.

A network of 35 motion accelerometers and GNSS (Global Navigation Satellite System) receivers is being set up on the island. It will vastly improve the tsunami-warning services under the Indian Tsunami Early Warning Centre (ITEWC), based in Hyderabad under the Indian National Centre for Ocean Information Systems (INCOIS).

Exactly 12 years ago, on Boxing Day, December 26, 2004, one of the deadliest earthquakes (9.3 magnitude), epicentred off the West coast of Sumatra, Indonesia, triggered a tsunami that killed over 2.3 lakh people across 14 countries, including 11,000 in India.

Since then, India has made rapid strides in establishing an early warning system with the help of various organisations, and partnered with international agencies involved in the study of earthquakes, tsunami and other ocean-related natural disasters.

The new network in Andaman is expected to help assess the rupture, area and direction of an earthquake, enabling a quick estimation of a potential tsunami. Already, a national network of near-real-time seismic and GNSS stations is in place.

The ITEWC is also tapping new geospatial technologies such as 3D GIS to map coastal areas. This information can be used to improve the accuracy of coastal inundation modelling, said Satheesh C Shenoi, Director, INCOIS, under the Ministry of Earth Sciences.

To test the efficiency of the existing facilities, the ITEWC had conducted a tsunami mock drill on September 7-8. It examined the communication links, and the readiness of the disaster management system and the local community to handle emergency situations. For the first time, around 40,000 people participated from about 350 villages from 33 coastal districts of eight States/UTs.

Preventing disasters

Reports said the fatal waves of the 2004 tsunami took anywhere between 15 minutes to seven hours to reach the coastlines of the 14 nations. The East and West coasts of India were affected two and four hours later, respectively.

In other words, there was enough time to warn people if there had been an early warning system.

Consequently, coastal communities in Tamil Nadu, Puducherry, Andhra Pradesh, Kerala, and Andaman and Nicobar Islands were devastated by the huge waves that caught them unawares.

The country now has a 24x7 early warning system that can issue tsunami bulletins in less than 10 minutes after any major earthquake in the Indian Ocean. This provides a response time of about 10-20 minutes to regions nearer to the epicentre and a few hours in the case of places farther away.

ITEWC comprises a real-time network of seismic stations, tsunami buoys and tide gauges. The centre analyses the collected data using high-power computational systems. Advisories are issued automatically to various stakeholders — from the Ministry of Home Affairs and the National Disaster Management Authority to State- and district-level disaster management centres, for follow-up action.

ITEWC has a network of seven tsunami buoy systems equipped with bottom-pressure recorders that transmit real-time data through satellite to INCOIS 24x7. The buoys are strategically placed at hypothetical tsunami sources of Andaman-Sumatra and Makran subduction zones (regions of the Earth’s crust where tectonic plates meet).

In addition, INCOIS has established a real-time network of 31 tide-gauge stations along the Indian coast, and receives real-time data from 300 international tide gauge stations across the world. The tide gauges supplement the work of the tsunami buoys.

Advisories are simultaneously sent to various stakeholders through multiple modes, such as email, fax, phone, GTS, SMS and INCOIS website updates.