Definition
- Also called harbour waves or seismic waves.
- They are a series of very large waves with extremely long wavelengths, in the deep ocean, the length from crest to crest may be 100 km or more.
- For Example – 2004 Tsunami
Formation
- Most tsunamis, including the most destructive ones, are generated by large and shallow earthquakes which usually occur near geological plate boundaries, or fault lines, where geological plates collide.
- When the seafloor abruptly deforms the sudden vertical displacements over large areas disturb the ocean’s surface, displace water, and generate tsunami waves.
Causes
- Earthquake
- Underground explosion
- Volcanic eruption
- Underwater landslides
- Meteorite impacts
Impacts of Tsunami
- Large-scale loss of lives and property
- Flooding and contamination of water
- Spread of diseases
- Contamination of soil and loss of biodiversity
- Psychological trauma to survivors
Government Measures
- Indian Ocean Tsunami Warning and Mitigation System – India joined after the 2004 tsunami.
- The Sendai Framework on Disaster Risk Reduction adopted in 2015 has put forward the following efforts to address tsunami-related hazards.
- Indian Tsunami Early Warning System in 2007
- Sagar Vani App:
- The Sagar Vani app has been developed by ESSO Indian National Centre for Ocean Information Services (INCOIS) under the Ministry of Earth Sciences.
- It is a software platform that uses state-of-the-art technology for the dissemination of ocean-related information and advisory services such as Potential Fishing Zone (PFZ) advisories, Ocean State Forecast (OSF), High Wave Alerts, and Tsunami early warnings.
Mitigation Measures
- Land-use planning in coastal areas should include restricted development and sustainable development strategies.
- Evacuation strategies should include the construction of tsunami evacuation structures and improvement in evacuation routes.
- Construction of seawalls, breakwaters, tsunami river gates, and developing forest barriers may also help in preventing extensive damage.
- Proper planning before the construction of building structures and the adoption of building codes should be done to prevent damage to life and property.
- Protection using coastal ecosystems like mangroves and coral reefs may help in lowering tsunami-related hazards.
- Setting up tsunami prediction and warning systems.
- Movement of population and necessary community assets away from vulnerable regions and planning for post-tsunami recovery should be done.
