On December 2004, Tsunami brought havoc on fourteen countries including India. Discuss the factors responsible for occurrence of Tsunami and its effects on life and economy. In the light of guidelines of NDMA (2010), describe the mechanism for preparedness to reduce the risk during such events.

Tsunamis are massive waves which are caused by either volcanic or seismic activity in deep ocean which displaces water. The waves on reaching shallow waters gain a height of several metres and cause maximum damage to life and property. Factors which cause Tsunami are as follows:

• Seismic activity under ocean: Earthquakes under the ocean primarily in subduction zone caused an oceanic plate to be forced down into the mantle by tectonic forces. This leads to abrupt and huge deformation of the ocean floor. This huge energy further gets transferred to water which surges and causes huge damage.
• Landslides: Submarine landslides releases a gigantic amount of energy at a rate which is not absorbed by the water completely. This causes the tsunami.
• Volcanic eruptions: Sudden displacement of water caused by a volcano, slope failure of a volcano or even a phreatomagmatic explosion and collapse causes huge waves resulting in a tsunami.
• Deep depressions: These are caused by low atmospheric pressures and winds which gain potential to lift water and make it move with the cyclone.
• Many other factors like nuclear tests, glacial convulsions etc. also have the potential to cause a tsunami.

Effects on life and economy:
Tsunamis cause tremendous loss of life, property, vegetation, trees, environment etc. The tsunamis cause heavy economic damage to seaside towns and beaches which heavily rely on tourism. Governments come under an obvious financial strain which can also result in a full-swing economic downturn. People have to rebuild their lives and livelihoods around the altered region.
NDMA has proposed many Guidelines (2010), for preparedness to reduce the risk of Tsunamis by recognition of major gaps in the same. Preparation of Tsunami Vulnerability Assessment and increasing public awareness in coastal areas on the subject is critical to reducing risk. Moreover, enforcement and complete compliance with town-planning by-laws is another crucial factor in mitigating the risk. Along with these a number of tsunami early warning systems like a Network of Land-based Seismic Stations, setting up of National Early Warning Centre etc. has been taken up in addition to capacity-building, training and education of all stakeholders.