The 2004 Indian Ocean earthquake was an undersea earthquake that occurred at 00.58 UTC (7.58.53 local time) on 26, December 2004. The earthquake generated a Tsunami that was among the deadliest disasters in modern history. 

Tsunami is a water wave caused due to tectonic activities under water and travels across oceans with very high speed and can inflict great damage to life and property at the shores. Tsunami is a word of Japanese language meaning "harbour wave", which is used to describe the large waves produced by an abrupt shifting of the sea floor which results in vertical displacement of the overlying water. When these waves reach the land by travelling, large distances across the ocean, they cause devastation on the coasts.

At magnitude of 9.0 on Richter Scale, it was the largest earthquake since the 9.2 magnitude Good Friday Earthquake of Alaska in 1964, and tied for fourth largest since 1900.

Tsunami Warning System & Preparedness

Modern technology is capable of offering advance warnings of such events in many areas, giving people the chance to escape to higher ground. The best way to avoid such disastrous results is by better preparation for any such events in advance. In case of the recent Sumatra earthquake and subsequent Tsunami, there was a lag of about 3 hours between the earthquake and the Tsunami reaching the coasts of Indian main land.

Recently, there have been efforts to detect the Tsunamis as they travel through the ocean. As Tsunamis may take a few hours to reach the coasts, if they are detected near the source, this time lag can be used to warn the people of a Tsunami heading towards them.

The extent of un-preparedness in India to handle Tsunami can be understood from the fact that no policy guidelines existed. In Indian scenario, the solution is not only to develop a warning system but also to launch a mass awareness campaign. 

Indian Scenario

Andaman & Nicobar islands and a large part of the east coast and a small part of the west coast of the Indian mainland suffered extensive damage due to the Tsunami. Tsunamis have not been regular phenomena at Indian coasts though many other countries have been plagued by more frequent Tsunamis for centuries.
The first reported Tsunami that hit the Indian coasts dates back to April 2, 1762. An earthquake at Bangladesh - Myanmar border triggered a Tsunami in the Bay of Bengal. Water in Hoogly at Kolkata rose by 2 m rise in water at Dhaka is reported to have capsized hundreds of boats and drowned many people. On December 31, 1881, an earthquake of magnitude 7.9 at Car Nicobar region generated Tsunamis with maximum crest height of 0.8 m which were recorded around the Bay of Bengal. The Krakatoa volcano eruption of 1883 had caused a Tsunami that was felt at Indian coasts also. In twentieth century also, Indian coasts have witnessed two major Tsunamis. On June 26, 1941, an 8.1 magnitude earthquake at Andaman Islands generated a Tsunami of about  1 m in height. The cellular jail in Port Blair was also damged and the earthquake was felt even in Madras and Colombo. Even the land of certain islands was reported to have sunk by about 60 cm. On November 28 1945, Makran coast of Pakistan had an earthquake of magnitude 8.0. this earthquake was accompanied by generation of Tsunamis and mud volcanoes. The Tsunamis were as high as 12 m at some of the Makran ports causing tremendous damage. The height of Tsunamis reached 11 m at kutch coasts and about 2 m at Mumbai about 15 persons were reported dead at Mumabi due to the Tsunami. About 4000 people died due to the earthquake and Tsunami. Apart from the development of a unified Tsunami warning system, the need of the hour is to train people to understand the hazard of Tsunami and the ways to minimise its devastating effects.

Earthquake and Associated Tsunami

The earthquake originated in the Indian Ocean just north of Simeulue island, off the western coast of northern Sumatra, Indonesia and triggered the most devastating Tsunami of the recorded history causing a death toll of more than 1,90,000/-. The resulting Tsunami devastated the shores of Indonesia, Sri Lanka, South India, Thailand and other countries with waves upto 30 m (100 feet). It caused serious damage and deaths as far as the east coast of Africa, with the farthest recorded death due to the Tsunami occurring at Port Elizabeth in South Africa, 8000 km (5000 miles) away from the epicentre. The true final toll may never be known due to bodies having been swept out to sea but as of January 13, 2005 (18 days after the event) the total number of deaths (approximate) as reported from various countries  was 159484. The break up is as follows:-
 

• Indonesia  : 113,306 (3,598 missing)
• Sri Lanka  : 29,825 (5,806 missing)
• India   : 10,672 (5,711 missing - 5625 on the Andaman & Nicobar islands)
• Thailand   : 5,309 (3,396 missing)
• Somalia  : 150
• Myanmar  : 59
• Maldives  : 82 (26 missing)
• Malaysia  : 68 (6 missing)
• Tanzania  : 10
• Bangladesh  : 2
• Kenya  : 1

HUDCO's   Post tsunami Rehabilitation Efforts 
 

• HUDCO along with CPWD ( Central Public Woks Department) and NBCC (National Building Construction Corporation) Teams visited Tamil Nadu and Pondicherry for preliminary damage assessment and also had meetings with local officials.
• HUDCO also participated along with the national team which visited A&N Island for presentation and the local meetings.
• HUDCO also participated at the national level in the meetings held by Hon'ble Home Minister, Hon'ble Agriculture Minister, National Disaster Management Authority (IIPA), Ministry of Urban Employment and Poverty Alleviation and Ministry of Urban development.
• MOUD proposed  two execution agencies as CPWD and NBCC for A&N Island and Pondicherrys and .  HUDCO has been asked to give the design and planning inputs for permanent rehabilitation.