Introduction

• Earthquakes and volcanic emissions cause the ocean bottom to move unexpectedly, bringing about abrupt arrival of energy by relocating seawater as high vertical waves are called tsunami (harbor waves) or seismic ocean waves.
• The speed of waves in the ocean is governed by water depth. It is higher in shallow water than in the deep ocean. As such, the effect of tsunamis is more negligible over the sea and more close to the coast, where they cause colossal scope annihilation.
• After reaching the coast, tsunami waves release a tremendous amount of energy stored in them. Water flows violently onto the land, damaging towns and cities, structures, buildings, and other infrastructure.
• As the coastal areas are heavily populated worldwide, and these are also centers of concentrated human activity, the damage of life and property will be much more severe by a tsunami than by various other natural hazards in the coastal regions.
• Tsunamis are regularly observed along the pacific ring of fire, mainly beside Japan, Alaska, the Philippines, and other islands of Southeast Asia, Indonesia, Malaysia,  Myanmar, Sri Lanka, and India, etc.
• Dissimilar from other natural risks, the alleviation of hazards created by the tsunami is tough, chiefly because losses are on a much greater gauge.

Tsunami

Prevention and Mitigation:

• One of the natural measures which could be adopted for mitigating the impact of the tsunami is using shoreline tree cover.
• Tree plantation is a cost-effective extended-lasting means of tsunami mitigation compared to artificial barriers.
• Some locations of the Indian Ocean where the tsunami struck in 2004 remained almost intact because the existing coconut palms and mangroves trees absorbed the tsunami’s energy.
• The Government of India chose to set up an Early Warning System to moderate such cyanogenic disasters. Indian National Center for Ocean Information Services (INCOIS), Hyderabad, was obligated to organize the whole task and make it functional. The tsunami cautioning framework is being used since the mid-2000s

NDMA Guidelines:

• It developed practical and effective ways for awareness generation, capacity building, education, training, and research & development for better tsunami risk management. This can be performed by conducting training and outreach events and campaigns.
• The exploring choices for effective dissemination of tsunami alert and warning messages created by the Indian National Center for Ocean Information Services to the appropriate agencies and vulnerable coastal communities exposed to tsunamis in a coordinated way.
• As a part of structural Mitigation measures, the Bureau of Indian standards should roll out the construction standards entitled ‘Criteria for Tsunami-Resistant Design of Structures’. This will act as brief management on the design and construction of new constructions and strategies for protecting lifeline and priority infrastructures from tsunamis along the seafront.
• Development of the robust techno-legal regime through efficient land-use practices, bio shields, shelterbelt plantation, and mangrove regeneration with community involvement.
• A robust mechanism for effective emergency response by civil defense volunteers wherever available, home guards, State Disaster Response Forces, and National Disaster Response Force.
• They were conducting exercises that included tsunami scenarios. Activities enhance the efficiency and effectiveness of tsunami disaster management during an actual event.
• Further, the guidelines explore the provisions of the Disaster Management Act 2005 to the mainstream concern of tsunami risk management in disaster management plans of various levels.

Case Study:

• On 26 December 2004, a magnitude 9.1 earthquake struck the Indian Ocean off the west coast of Northern Sumatra. This resulted in the Indian Ocean tsunami, which impacted 13 countries and killed 230,000 people.
• The epicentre was very close to heavily populated coastal cities, such as Indonesia.
• There was no early warning system for tsunami in the Indian Ocean. This may have saved more lives in countries far away from the epicentre.
• Mangrove forests had been cleared in some coastal areas to make way for tourist developments. This resulted in less natural protection.

Effects on India:

• Southwest Coast comprises Kerala, which suffered significant damage that impacted the largest number of people compared to any other state. But suffered a relatively lower loss of life. The Kanyakumari district of Tamil Nadu suffered heavy loss of life due to a large extent, to human-created local topographical features.
• Southeast Coast: This comprises the rich alluvial delta region of the Tamil Nadu coast and Pondicherry, which experienced maximum wave heights and recorded the ultimate loss of life and damage in overall mainland India.
• East Coast: This comprises Andhra Pradesh, which suffered marginal damage and loss of life. 

Conclusion

Tsunamis occurs due to movement in the inner surface of earth  and gives rise to deadly ocean waves. As such, the effect of tsunamis is more negligible over the sea and more close to the coast, where they cause colossal scope annihilation. After reaching the coast, tsunami waves release a tremendous amount of energy stored in them. Water flows violently onto the land, damaging towns and cities, structures, buildings, and other infrastructure. One of the best natural ways which could be adopted for mitigating the impact of the tsunami is using shore line tree cover. Tree plantation is a cost-effective extended-lasting means of tsunami mitigation compared to artificial barriers. NDMA has also developed practical and effective ways for awareness generation, capacity building, education, training, and research & development for better tsunami risk management. This can be performed by conducting training and outreach events and campaigns.